CE-102 DEF1 Engineering Economics

Engr. Carmel S. Burlat

Construction Materials and Testing

TOPIC 1 The Construction Process and Sustainability
THE CONSTRUCTION PROCESS
1. OWNER
The construction process is initiated when a person or organization, which may be public
or private, decides to improve the land with permanent or semipermanent additions. The
initiator of a construction project, hereafter called the owner, therefore has a need, as well
as the required financing, to complete the process.
2. ENGINEER
The architect or engineer prepares plans, called working drawings, showing details and
how the completed project will look.
3. SPECIFICATION
These documents explain in detail what materials to use, the characteristics of the
materials, and what methods of inspection and testing the owner’s representative will use
to evaluate the selected materials.
4. CONTRACTOR
selected by bid on public works projects, and by bid or negotiation on private projects,
enters a contract with the owner to provide a Completed project in accordance with the
project contract documents.
5. UNIT PRICE OR LUMP SUM
The most common contract, depending upon the type of construction project.
PROJECT SCHEDULE
1. QUALITIES OF SELECTING MATERIALS
→ The construction industry requires materials for a vast range of uses.
1. Footing
a. Distribute the weight of the building to the soil.
b. Resist cracking despite uneven soil settlement.
c. Resist corrosive attack from soil and water.
2. Basement floor
a. Provide a smooth surface.
b. Resist wear.
c. Resist cracking despite upward water pressure or uneven soil settlement.
d. Keep moisture out.
e. Resist corrosive attack from soil and water.
3. Basement walls
a. Support the rest of the building.
b. Resist lateral side pressure from the earth.
c. Keep moisture out.
d. Resist corrosive attack from soil and water.
4. Other floors and ceilings
a. Provide a smooth surface.
b. Resist wear.
c. Support furniture and people without sagging excessively or breaking.
d. Provide a satisfactory appearance.
e. Clean easily.
f. Insulate against noise transmission.
5. Outside walls
a. Support floors and roof
b. Resist lateral wind pressure.
c. Provide a satisfactory appearance inside and out.
d. Insulate against noise and heat transmission.
e. Keep moisture out.
6. Partitions
a. Support floors and roof
b. Provide a satisfactory appearance.
c. Insulate against noise transmission.
7. Roof
a. Keep moisture out.
b. Support snow and other weights
c. Resist wind pressure and wind uplift.
d. Provide a satisfactory appearance.
e. Insulate against noise and heat transmission.
→ Any satisfactory choice always requires a knowledge of construction materials and an
adequate selection procedure.
→ A designer is selected who, among other things, is responsible for selection of all
construction materials to achieve the desired performance within the budget cost.
✓ Performance
✓ Appearance
 ✓ Original Cost
✓ Maintenance Expense
✓ Useful Life Expectancy

2. SUSTAINABILITY
SUSTAINABLE DEVELOPMENT
Development that meets the needs of the present without compromising the ability of future
generations to meet their own needs. (The Brundtland Commission,1987).
✓ Longevity
✓ Energy Efficiency
✓ Reusability and Recycling
3. PROPERTIES OF MATERIALS
Thermal Expansion
A piece of material, if heated uniformly, expands, with each unit length becoming
a certain percentage longer. This elongation takes place in all directions and is
somewhat different for each material.
coefficient of expansion
A decimal representing the increase in length per unit length per degree increase
in temperature.

Thermal Conductivity
Heat movement takes place by conduction through any solid object separating
areas of different temperatures. The rate is measured as thermal conductivity (U)
in British thermal units (Btu) of heat transmitted per square foot of cross section
per hour per °F difference in temperature between the two sides of the material.
Insulation
Which is material with a very low U, is used to line large surfaces to lessen the
rate of heat flow. The U of a material varies directly with its density.
Resistance
The resistance that construction materials offer to the flow of heat is called
thermal resistance and is designated by the letter R. The reciprocal of the heat
transfer coefficient U is R with a unit value of (hrft2°F/Btu).
Strength and Stress
 A force is a push or pull that has a value and a direction. Loads on structures are
separated into dead loads and live loads.
→ Dead loads include the weight of the structural elements as well as
permanent equipment such as boilers and air-conditioning units.
→ Live loads are those imposed loads which may or may not be present
and include occupants, furniture, wind, earthquake, and other variable
load conditions.
Stress is force per unit area
over which the force acts. It
is obtained by dividing the
force by the area on which it
acts and is expressed as
pounds per square inch
(psi) or kips per square inch
(Ksi). A kip is equivalent to
1000 lb.
→ Therefore, the
strength of a
material in
technical terms is
equal to the
stress that the
material can
resist. Strength
has the same
units as stress, that is, psi, Ksi, or megapascals (MPa).

FAMILIARIZATION WITH APPARATUS & EQUIPMENT USED IN TESTING OF MATERIALS

Inspection and Testing
Inspection means examining a product or observing an operation to determine
whether it is satisfactory. The inspection may include scaling the dimensions,
weighing, tapping with a hammer, sifting through the fingers, etc. However, the
results of the inspection and minor tests are not generally measurable. Often an
inspection raises questions which are then resolved by testing.
A test consists of applying some measurable influence on the material and
measuring the effect on the material.

Quality Assurance or Acceptance:

→ Inspection and tests performed to determine whether or not a material
or product meets specific requirements in order to decide whether or
not to accept or reject the material or product.
→ A manufacturer performs such inspections and tests on raw materials
he intends to use.
→ A builder performs these inspections and tests on manufactured
products and raw materials that he intends to use; and the owner’s
representative performs them on the builder’s finished product.
Quality Control:
→ Inspection and tests performed periodically on selected samples to
ensure that the product is acceptable. A supplier or manufacturer
monitors his own operation by periodic checks of his product.
→ The builder may check his product similarly. If control measures show
the product to be below standards, the reason is determined, and
corrective measures taken.
Research and Development:
→ Inspection and tests performed to determine the characteristics of new
products and also to determine the usefulness of particular inspection
procedures and tests to judge characteristics or predict behavior of
materials.
Standards:
Most standards represent basic
performance levels. When higher
levels are required they may have to
be drafted carefully for a given
specification.

Standards a measure performance

in a carefully defined reproducible
manner. They are subject to change
as understanding of materials properties increases, experimental techniques improve and
performance requirements evolve.

The best evidence of conformity is obtained when independent tests are carried out by
some qualified testing authority.
Sample Standards:
1. British Standards
2. ASTM Standards (American Society for Testing and Materials)
3. ISO Standards (International Organization for Standardization)
4. Philippine Standards
Quality can be simply defined as fitness for purpose. There will always be a cost implication
as the target quality levels rise.
Factors to be considered when arriving a target level for a specific item:
1. What are the possible failure modes?
2. What are the consequences of failure in safety terms?
3. How easy it is to inspect or maintain the item?
4. How easy or costly would it be to replace the item if it failed?
Quality Control is the practical procedure which assists in the production of a quality
product.
Quality Management involves the operation of a comprehensive system of quality control,
including employment of a quality control, including employment of a quality manager to
oversee the maintenance of quality standards and keeping of systematic written records of
every part of a design, production, or other process.
TOPIC 2 Aggregate for Concrete
AGGREGATES
→ aggregates are particles of random shape.
→ found in nature as sand, gravel, stones, or rock that can be crushed into particles.
→ by-products or waste material from an industrial process or mining operation.
→ coarse aggregate: (1) Aggregate predominantly retained on the No. 4 (4.76-mm)
sieve; or (2) that portion of an aggregate retained on the No. 4 (4.76-mm) sieve.
→ fine aggregate: (1) Aggregate passing the 3⁄8 in. sieve and almost entirely passing
the No. 4 (4.76-mm) sieve and predominantly retained on the No. 200 (74-micron)
sieve; or (2) that portion of an aggregate passing the No. 4 (4.76-mm) sieve and
retained on the No. 200 (74-micron) sieve.
→ gravel: (1) Granular material predominantly retained on the No. 4 (4.76-mm) sieve
and resulting from natural disintegration and abrasion of rock or processing of weakly
bound conglomerate; or (2) that portion of an aggregate retained on the No. 4 (4.76-
mm) sieve and resulting from natural disintegration and abrasion of rock or processing
of weakly bound conglomerate.
→ sand: (1) Granular material passing the 3/8-in. sieve and almost entirely passing the
No. 4 (4.76-mm) sieve andpredominantly retained on the No. 200 (74-micron) sieve,
and resulting from natural disintegration and abrasion of rock or processing of
completely friable sandstone; or (2) that portion of an aggregate passing the No. 4
(4.76-mm) sieve and predominantly retained on the No. 200 (74-micron) sieve, and
resulting from natural disintegration and abrasion of rock or processing of completely
friable sandstone.
→ bank gravel: Gravel found in natural deposits, usually more or less intermixed with
fine material, such as sand or clay, or combinations thereof; gravelly clay, gravelly
sand, clayey gravel, and sandy gravel indicate the varying proportions of the materials
in the mixture.
→ crushed gravel: The product resulting from the artificial crushing of gravel with
substantially all fragments having at least one face resulting from fracture.
→ crushed stone: The product resulting from the artificial crushing of rocks, boulders,
or large cobblestones, substantially all faces of which have resulted from the crushing
operation.
→ crushed rock: The product resulting from the artificial crushing of all rock, all faces of
which have resulted from the crushing operation or from blasting.
→ blast-furnace slag: The nonmetallic product, consisting essentially of silicates and
aluminosilicates of lime and of other bases, which is developed in a molten condition
simultaneously with iron in a blast furnace.
CHARACTERISTICS OF AGGREGATES
Particle Size
✓ size of aggregate bigger than 4.75 mm is considered as coarse aggregates
and less as fine aggregate.
✓ nominal sizes of coarse aggregate are 10 mm, 20 mm, etc.
 ✓ maximum practical size of aggregate should not exceed one-fourth of the
minimum thickness of member, 5mm less than the minimum cover to
reinforcement and 5 mm less than the minimum clear distance between main
reinforcement for reinforced
concrete work.
Shape
✓ Rounded
✓ Irregular
✓ Angular
✓ Flaky
✓ Elongated
Surface Texture
SURFACE TEXTURE CHARACTERISTICS EXAMPLES
Glassy Conchoidal fracture Black flint vitreous slag
Water-worn, or smooth
fracture of
Smooth sandstone
fine-grained rock or
laminated rock
Fracture showing more
Granular or less uniform rounded Granite gabbro, gneiss
grains.
Easily visible crystalline
constituents.
Rough fracture of fine or
Crystalline (coarse
medium-grained rock Basalt trachyte
crystalline fine)
containing no easily
visible crystalline
constituents.
Brick, Pumice, foamed
Honeycombed and With visible pores and
slag, clinker, expanded
porous cavities
clay
Strength of Aggregate
✓ compressive strength of the majority of rock aggregates commonly used is in the
range of 45 to 550 N/sq.mm.
✓ strength of concrete is generally between 15 to 50 N/ sq.mm.

SOURCES OF AGGREGATES
NATURAL AGGREGATE
SAND AND GRAVEL MINE (PIT):
✓ sand, gravel, or larger stones, and bedrock reduced to particle size by
manufacturing methods.
✓ come from unconsolidated sand and gravel deposits.
✓ typically deposited by streams or glaciers.
QUARRY:
✓ come from the bedrock deposits. Bedrock, which is consolidated rock
includes: granite, basalt, quartzite, gabbro, etc.
CONTRIVED AGGREGATE
RECYCLE:
 ✓ products that include crushed concrete, bituminous, or demolition
debris and in some instances taconite tailings.
METHODS OF EXTRACTION AND PROCESSING
UNDERWATER SOURCES
✓ Aggregate is brought up from lake and river bottoms by barge-mounted dredges
with a single scoop or an endless chain of scoops and by dragline.
LAND SOURCES
✓ Aggregates are excavated from natural banks, pits, or mines on land by bucket
loaders, power shovels, draglines, and power scrapers.
ROCK TYPES
Rock, from which most aggregate is
derived, is of three types according
to origin—igneous, sedimentary,
and metamorphic.
IGNEOUS ROCK was at one time
molten and cooled to its present
form.
✓ Granite
✓ Gabbro
✓ Basalt
✓ Diabase
✓ Pumice
✓ Scoria
SEDIMENTARY ROCK at one time
consisted of particles deposited as
sediment by water, wind, or glacier.
Most were deposited at the bottom
of lakes or seas. The pressure of
overlying deposits together with the
presence of cementing materials
combined to form rock.
✓ Siltstone
✓ Claystone
✓ Shale
✓ Limestone
✓ Dolomite
✓ Chert
METAMORPHIC ROCK is either
igneous or sedimentary rock that
has been changed in texture,
structure, and mineral composition,
or in one or two of these
characteristics, by intense geologic
heat or pressure or both.

PROPERTIES AND USES

Qualities that indicate the usefulness of aggregate particles to the construction industry are
as follows:
 1. Weight.
2. Strength of the particles to resist weathering, especially repetitive freezing and
thawing.
3. Strength as demonstrated by the ability of the mass to transmit a compressive force.
4. Strength as demonstrated by the ability of the individual particles to resist being
broken, crushed, or pulled apart.
5. Strength of the particles to resist wear by rubbing or abrasion.
6. Adhesion or the ability to stick to a cementing agent.
7. Permeability of the mass, or the ability to allow water to flow through, without the loss
of strength or the displacement of particles.

AGGREGATE AND STRENGTH

If particles with flat surfaces were piled vertically, as shown in Figure a, a compressive
force could be transmitted through the pile just as it is in a structural column made of stone.
Aggregate cannot be piled in this way. It appears as shown in Figure b when in use. Figure
b illustrates a cross section through a container of aggregate with a concentrated weight or
force acting downward on one particle of aggregate. Because of the random arrangement
of particles, the concentrated load is necessarily transmitted to more particles as the force
is transmitted deeper into the container and thereby is spread over most of the bottom of
the container.
In order for the load to spread horizontally, there must be a horizontal force. The vertical
load from the top is transmitted through the points of contact, as indicated in Figure c, over
an ever-larger area with ever smaller forces. The originally vertical force has a horizontal
component at each point of contact below the point of original application. At the points of
contact, if the surfaces are not perpendicular to the line of force, there is a tendency for the
upper particle to slide across the lower particle or push the lower particle aside so that the
lower one slides across the particle below it. The tendency to slide transversely is a
shearing stress, and the strength to resist the sliding is the shearing strength of the
aggregate.
 Factors which increase the shearing strength of aggregates.
1. A well-graded aggregate is stronger than one not well graded.
2. The larger the maximum size of aggregate is, the greater its strength. Larger particles
provide greater interlocking, because particles must move upward for greater
distances to override them.
3. The flatter, broken faces the particles have, the greater the strength developed
through interlocking. Flat faces fit together more compactly with more contact between
faces than if the particles are rounded. This does not mean the particles themselves
should be flat. Flat particles slide readily over each other and result in lack of strength.
4. Compaction, especially by vibration, increases the shearing strength of aggregate of
any size, shape, and gradation.
5. Rough particle surfaces increase strength because of greater friction between them.

COMPACTION
Compaction is the densification of a material resulting in an increase in weight per unit
volume.
PAVEMENT BASE
Typical pavement
construction consists of
several layers or courses
which reduce the pressure
of concentrated wheel
loads so that the
underlying soil or
foundation is not
overloaded.
STABILIZING AGGREGATES
Aggregate strength can be improved by the addition of measured quantities of clay, which
is a soil with very fine particles having properties unlike any of the larger soil particles. One
of these properties is cohesion or the tendency to stick together. The strength due to
cohesion is added to the shearing strength possessed by the aggregate. The clay,
therefore, acts as a cement or paste. Other substances are also used for the same purpose.
These include salts, lime, portland cement, and bituminous cement. The use of these other
substances to increase strength is called stabilization.
PERMEABILITY AND FILTERS
Permeability is a measure of
the ease with which a fluid,
most commonly water, will
flow through a material.
Gravels have relatively high
permeability, whereas
sands and silts have lower
permeability. The
approximate permeability of
a clean, uniform filter sand
can be determined using
Hazen’s formula. The coefficient of permeability is denoted ask with units of cm/s.

TESTS
Size and Gradation
The important features are
range of sizes, or smallest and largest
particles, and gradation, or distribution
of sizes within the range covered.
Gap-Graded Aggregates
Gap graded or skip graded means that
most particles are of a large size or a
small size with very few particles of an
intermediate size.
Surface Area
→ Surface area of aggregate is important in certain computations.
→ Of all possible particle shapes, a sphere has the lowest ratio of surface area to
volume or weight.
→ The following calculation shows the
ratio of surface area to volume for a
sphere:

→ The ratio is 3 divided by the radius of the sphere. It is greater for small particles
than for large particles because the ratio becomes greater as the radius becomes
smaller.
→ It is also of importance if aggregate particles are to be bound together for
strength.
Weight-Volume Relationships
→ The total volume of an aggregate includes solid particles and voids between
them.
→ The total volume is important because aggregate must be ordered to fill a specific
volume for certain purposes and its intended use (e.g., filter, roadbed).
→ Volume of aggregate in relation to its weight is important for determining quantity
needed and payment by weight.
 Various combinations are used to relate weight and volume, depending on how the
aggregate is to be used.
1. The volume of aggregate may include solid matter, plus pores in the particles, plus
voids. This is called bulk volume of aggregate.
2. The volume may include solid matter, plus pores in the particles but not voids. This
is called the saturated, surface-dry volume.
3. The volume may include solid matter only, not pores or voids. This is called solid
volume.
4. The weight may include solid matter, plus enough water to fill the pores, plus free
water on the particle surface. This is called wet weight.
5. The weight may include solid matter, plus enough water to fill the pores. This is
called saturated, surface-dry weight.
6. The weight may include solid matter only. This is called oven-dry weight.
Density and Voids
→ Bulk density of aggregate is defined as the mass over a unit volume of bulk
aggregate material, in which the volume includes the volume of the individual
particles without voids and the volume of the individual particles with voids
between the particles.
→ Expressed in (kg/m³), (Ib/ft³) and (Ib/in³).
Relative Density
→ The relative density (specific gravity) of an aggregate is the ratio of its mass to
the mass of an equal volume of water.
→ Relative Density = Mass of the Aggregate/Mass of equal volume of water
→ Most aggregates have a relative density between 2.4-2.9 with a corresponding
particle (mass) density of 2400-2900 kg/m3 (150-181 lb/ft3). Here, for coarse
aggregates, the standard test method has been explained in ASTM C
127(AASHTO) and for fine aggregates, the standard test method has been
explained in ASTM C 128 (AASHTO). [3] The relative aggregate density can be
determined on an oven-dry basis or a saturated surface-dry (SSD) basis.
Absorption and Surface Moisture
→ This gives an idea on the internal structure of aggregate.
→ aggregates absorption: It is the increase in mass due to water in the pores of the materials.
→ surface moisture: It is defined as moisture in excess of that contained by aggregate when in a saturated
surface-dried condition.
How Do You Measure Moisture Content in Aggregate?
There are a few different ways to determine the moisture content of aggregate,
including the drying method, displacement method, calcium carbide method,
electrical meter method, and automatic measurement.
→ Absorption And Surface Moisture Formula
> WATER ABSORPTION = [(A-B)/B] x 100%

MISCELLANEOUS TEST
Toughness
→ Toughness of aggregates is defined as the ability to resist impact loading.
→ The aggregate impact value test on aggregate: This is used to determine the toughness of the
aggregates. In this test, aggregate sample is subjected to 15 blows by a metallic hammer of mass 14 kg
and a free fall height of 38 cm.
→ Apparatus: Impact Testing Machine, Sieves, Tamping Rod, Oven, and Balance.
→ Aggregate Impact Value Formula:
𝑊
> 𝐴𝑔𝑔𝑟𝑒𝑔𝑎𝑡𝑒 𝐼𝑚𝑝𝑎𝑐𝑡 𝑉𝑎𝑙𝑢𝑒 = 2 × 100%
𝑊1
Soundness Test
→ The test is performed by exposing an aggregate sample to repeated immersions
in saturated solutions of sodium or magnesium sulfate followed by oven drying.
→ Apparatus Required: balance, oven, Sieves, wire mesh basket, container, and
chemical solution (sodium sulphate solution and magnesium sulphate solution).
PROPER HANDLING AND STORAGE OF AGGREGATES
✓ It is crucial in construction and civil engineering projects. Aggregates are typically
utilized as a raw material for concrete and asphalt, as well as for drainage and
erosion control. To ensure the cleanliness, dryness, and contamination-free state of
aggregates, and to prevent material loss and safety risks, some guidelines should be
followed.
✓ These guidelines include transporting aggregates in suitable and clean vehicles,
unloading the material on stable and level surfaces, stockpiling on appropriate
surfaces away from drainage channels, covering the material with a tarp or other
suitable material to prevent weather exposure and contamination taking samples
periodically to test for characteristics such as particle size and moisture content, and
practicing safe handling and lifting procedures to prevent accidents. By following
these practices, one can ensure that the aggregates remain in good condition and
that the project is executed safely and efficiently.
TESTING OF AGGREGATES
✓ Testing of aggregates is a crucial aspect of construction and civil engineering
projects to ensure that the aggregates meet the required specifications and
standards. Various tests are used to determine the properties of aggregates such as
particle size, shape, texture, density, and strength. These tests include sieve
analysis, flakiness and elongation index, bulk density and voids, water absorption,
crushing value, and Los Angeles abrasion test. The results of these test are used to
evaluate the suitability of the aggregates for use in construction projects. By ensuring
that the aggregates meet the required specifications and standards, the quality and
durability of the final product can be ensured.

TOPIC 3 Portland Cement

CEMENT
 → Cement is a fine gray powder created from raw materials and chemical compounds
that professionals use in various types of construction jobs. It's a manufactured
ingredient used in concrete. Professionals create cement by mixing raw materials with
metals and minerals such as aluminum, iron, calcium and silicon before heating it to
high temperatures to form a solid material called clinker. Clinker is then ground into a
powder sold as cement to ready-mix concrete companies.
→ Raw materials in cement may include:
> Chalk
> Clay
> Iron ore
> Limestone
> Shale
> Shells
> Silica sand
> Slag
PORTLAND CEMENT
→ Portland cement is a common ingredient in manufacturing concrete. This type of
cement produces paste that, along with water, combines with rock and sand in order
to harden.
→ How it’s made: Portland cement is obtained by heating limestone and clay or other
silicate mixtures at high temperatures (>1500°C) in a rotating kiln. The resulting
clinker, when cooled, is mixed with gypsum (calcium sulfate) and ground to a highly
uniform fine powder.
→ Composition: Portland cement consists of four major clinker compounds, C3S, C2S,
C3A, and C4AF together with the gypsum added during grinding.
→ Application: Portland cement is used for general construction purposes where special
properties are not required. It is normally used for the reinforced concrete buildings,
bridges, pavements, and where soil conditions are normal. It is also used for most
concrete masonry units and for all uses where the concrete is not subject to special
sulfate hazard or where the heat generated by the hydration of cement is not
objectionable. It has great resistance to cracking and shrinkage but has less
resistance to chemical attacks.
HISTORY OF CEMENT
→ Ancient Times: In ancient times, Romans, Egyptians, and Indians used some kind of
cementing materials in their construction. Egyptians used burnt gypsum as cementing
materials. In the absence of natural volcanic ash, Romans used powdered pottery or
tiles as pozzolana. Romans added milk, blood & lard in the mix to improve the
workability. The blood Hemoglobin is a powerful air entraining agent and plasticizer.
→ 1700's
> After 1756, John Smeaton carried out extensive experiments to find out the
best material to withstand severe action of sea water.
> In 1796 hydraulic cement was produced by burning the nodules of
argillaceous lime stones. (in 1800 it was given the name Roman cement. It
was in use till 1850 then OPC was introduced).
 → 1800's
> In 1824, Portland cement was invented. Joseph Aspdin of England is
credited with the invention of modern Portland cement. He named his
cement Portland, after a rock quary that produced very strong stone.
> In 1845, Isaac Johnson fired chalk and clay at much higher temperatures
than the Aspdins, at around 1400-1500C, which led to the mixture clinkering,
and produced what is essentially modern-day cement.
> From 1850, the use of concrete made from Portland cement increased
considerably.
> In 1878, The first cement standard for Portland cement was approved in
Germany.
→ 1900's
> 1900s, rotary kilns replaced the original vertical shaft kilns, as they use
radiative heat transfer, more efficient at higher temperatures. Achieving a
uniform clinkering temperature and produces stronger cement.
CLASSIFICATION OF CEMENT
→ Natural: It is manufactured from stones containing 20 to 40 percent of clay, the
remainder being carbonate of lime mixed with carbonate of magnesia. The stones are
first burnt and then crushed.
→ Artificial: Artificial cements are those manufactured in a factory, for example Portland
cement and other special cements.
→ Different types of artificial cement as classified by the Bureau of Indian
Standards (BIS):
1. Ordinary Portland Cement
a. 33 grade- IS:269-1989
b. 43 grade- IS:8112-1989
c. 53 grade- IS:12269-1987
2. Rapid Hardening Cement-IS:8041-1990
3. Extra Rapid Hardening Cement
4. Low Heat Portland Cement-IS:12600-1989
5. Portland Slag Cement-IS: 455-1989
6. Portland Pozzolana Cement-IS: 1489-1991
7. Sulphate Resisting Portland Cement IS: 12330-1988
8. White Portland Cement IS: 8042-1989
9. Colored Portland Cement-IS: 8042-1989
10. Hydrophobic Cement IS: 8043-1991
11. High Alumina Cement IS: 6452-1989
12. Super Sulphated Cement-IS: 6909-1990
13. Special Cement
a. Masonry Cement
b. Air Entraining Cement
c. Expansive Cement
d. Oil Well Cement
MANUFACTURE OF PORTLAND CEMENT
 → The raw materials required for manufacture of Portland cement are calcareous
materials, such as limestone or chalk, and argillaceous material such as shale or clay.
→ The process of manufacture of cement consists of grinding the raw materials, mixing
them intimately in certain proportions depending upon their purity and composition
and burning them in a kiln at a temperature of about 1300 to 1500°C, at which
temperature, the material sinters and partially fuses to form nodular shaped clinker.
→ The clinker is cooled and ground to fine powder with addition of about 3 to 5% of
gypsum.

Processes of processing Portland Cements

✓ WET: For many years the wet process remained popular because of the
possibility of more accurate control in the mixing of raw materials.
✓ DRY: The dry process gained momentum with the modern development of
the technique of dry mixing of powdered materials using compressed air
Criteria Dry Process Wet Process
Hardness of raw material Quite hard Any type of raw material
Fuel consumption Low High
Time of Process Lesser Higher
Quality Inferior Quality Superior quality
Cost of Production High Low
Overall cost Costly Cheaper
Physical state Raw mix (solid) Slurry (liquid)
TYPES OF PORTLAND CEMENT ASTM C150

ASTM TYPE. I (NORMAL)

✓ This type is a general concrete construction cement utilized when the special
properties of the other types are not required.
✓ It is generally not used in large masses because of the heat generated due
to hydration.
✓ Its uses include pavements and sidewalks, reinforced concrete buildings,
bridges, railway structures, tanks, reservoirs, culverts, water pipes, and
masonry units.
ASTM TYPE. II (MODERATE HEAT OR MODIFIED)
✓ Type II cement is used where resistance to moderate sulfate attack is
important, as in areas where sulfate concentration in groundwater is higher
than normal but not severe.
✓ They are used in warm weather concreting because of their lower
temperature rise than Type I.
✓ The use of Type II for highway pavements will give the contractor more time
to saw control joints because of the lower heat generation and resulting
slower setting and hardening.
ASTM TYPE. III (HIGH-EARLY-STRENGTH)
✓ Type III cements are used where an early strength gain is important and heat
generation is not a critical factor.
✓ In cold-weather concreting, Type III allows a reduction in the heated curing
time with no loss in strength.
ASTM TYPE. IV (LOW HEAT)
✓ Type IV cement is used where the rate and amount of heat generated must
be minimized.
✓ It is primarily used in large mass placements such as gravity dams.
ASTM TYPE. V (SULFATE-RESISTING)
✓ Type V is primarily used where the soil or groundwater contains high sulfate
concentrations, and the structure would be exposed to severe sulfate attack.
AIR-ENTRAINING PORTLAND CEMENT
✓ These cements provide the concrete with improved resistance to freeze–thaw
action and to scaling caused by chemicals and salts used for ice and snow
removal.
✓ Concrete made with these cements contains microscopic air bubbles,
separated, uniformly distributed, and so small that there are many billions in
a cubic foot.
WHITE PORTLAND CEMENT
✓ The selected raw materials used in the manufacture of white cement have
negligible amounts of iron and manganese oxide, and the process of
manufacture is controlled to produce the white color.
✓ Its primary use is for architectural concrete products, cement paints, tile
grouts, and decorative concrete.
 PORTLAND BLAST-FURNACE SLAG CEMENTS
✓ The slag is obtained by rapidly chilling or quenching molten slag in water,
steam, or air. Portland blast-furnace slag cements include two types, Type IS
and Type IS-A, conforming to ASTM C595.
✓ These cements can be used in general concrete construction when the
specific properties of the other types are not required.
PORTLAND-POZZOLAN CEMENTS
✓ IP, IP-A, P, and P-A designate the portland-pozzolan cements with the A
denoting air-entraining additives as specified in C595.
✓ They are used principally for large hydraulic structures such as bridge piers
and dams.
MASONRY CEMENTS
✓ Type I and Type II masonry cements are manufactured to conform to ASTM
C91 and contain portland cement air-entraining additives, and materials
selected for their ability to impart workability, plasticity, and water-retention
properties to the masonry mortars.

SPECIAL PORTLAND CEMENTS

OIL WELL CEMENT

✓ Oil well cement is designed to
withstand high temperatures and
pressures. It is usually slow setting.
✓ Typically made by blending Portland
cement with additives such as silica
fume, fly ash, and calcium aluminate.
✓ It is used for sealing oil wells.
WATERPROOF PORTLAND CEMENT
✓ Waterproof portland cement is manufactured by the addition of a small
amount of calcium, aluminum, or other stearate to the clinker during final
grinding.
✓ The resulting cement has a lower porosity, which reduces the amount of
water that can penetrate into the cement and cause damage.
✓ Waterproof portland cement is used in a variety of applications where
resistance to water is important, such as in the construction of water tanks,
swimming pools, basements, and foundations.
WHITE AND COLOURED PORTLAND CEMENT
✓ White and Coloured Portland Cement is manufactured from pure white chalk
and clay free from iron oxide.
Greyish colour of cement is due to iron oxide. So, the iron oxide is reduced
and limited below 1 per cent, while coloured cements are made by adding 5
- 10 per cent colouring pigments before grinding.
✓ These cements are used for making terrazzo flooring, face plaster of walls
(stucco), ornamental works, and casting stones.
 QUICK SETTING PORTLAND CEMENT
✓ This cement is produced by grinding portland cement clinker with a small
amount of gypsum and small percentage of aluminium sulphate is added. It
is ground much finer than ordinary Portland cement.
✓ This cement is prepared by adding a small percentage aluminum sulphate
which reduce the percentage of gypsum or retarded for setting action and
accelerating the setting action of cement.
✓ This cement is used to lay concrete under static water or running water.
RAPID HARDENING CEMENT
✓ This cement is made by increasing the amount of calcium silicate in the mix
and is used for applications where early strength development and rapid
hardening are required.
✓ This cement has same initial and final setting times as that of ordinary
cement. But it attains high strength in early days due to; Burning at high
temperature, Increased lime content in cement composition, and Very fine
grinding.
✓ This cement is used is situations where rapid strength gain and quick
construction schedules are required like Road repairs, and Marine structures.

CHEMICAL COMPOSITION OF PORTLAND CEMENT

→ Portland cements are
composed of four basic
chemical compounds,
shown with their names,
chemical formulas, and
abbreviations:
TRICALCIUM SILICATE C3S
✓ TRICALCIUM SILICATE hardens rapidly and is largely responsible for initial
set and early strength. In general, the early strength of portland cement
concretes will be higher with increased percentages of C3S.
DICALCIUM SILICATE C2S
✓ DICALCIUM SILICATE hardens slowly, and its effect on strength increases
occurs at ages beyond one week.
TRICALCIUM ALUMINATE C3A
✓ Tricalcium aluminate contributes to strength development in the first few days
because it is the first compound to hydrate. It is, however, the least desirable
component because of its high heat generation and its reactiveness with soils
and water containing moderate-to-high sulfate concentrations. Cements
made with LOW C3A contents usually generate less heat, develop higher
strengths, and show greater resistance to sulfate attacks.
TETRACALCIUM ALUMINOFERRITE C4AFe
✓ Tetracalcium aluminoferrite assists in the manufacture of portland cement by
allowing lower clinkering temperature. C4AFe contributes very little to the
strength of concrete even though it hydrates very rapidly.
A. FINENESS
→ Fineness refers to the size of cement particles which directly affect the performance
and the use of cement. The cement fineness is measured by sieve analysis method
or specific surface area.
→ Sieve analysis method requires that the screenings left on the square-hole sieve of
0.090mm should not exceed 10%. Specific surface area is calculated by the total
surface area of 1 kg cement (m2/kg). The specific surface area of Portland cement
should exceed 300 m2/kg.
→ Fineness of Cement Apparatus:

→ Fineness Test:
B. SOUNDNESS
→ The soundness of cement refers to the stability of the volume change in the process
of setting and hardening. If the volume change is unstable after setting and
hardening, the concrete structures will crack, which can affect the quality of buildings
or even cause serious accidents, known as poor dimensional stability.
→ Boiling methods:
✓ Pat test
To make the cement paste of normal consistency into cement cake, boil it for
3 hours, and then observe it by naked eyes. If there is no crack and no
bending by ruler inspection, it is called qualified soundness.
✓ Le Chatelier test
To measure the expansion value after the cement paste is boiled and get
hardened on Le Chatelier needles. If the expansion value is within the
required value, its stability is qualified.

Soundness Test = Length expansion AFTER boiling – Length of expansion

BEFORE boiling
NOTE: The value should not exceed to 10mm for Portland cement.

C. SETTING TIME
→ The setting time of cement includes the initial setting time and the final setting time.
The initial time refers to the time that cement turns into paste by mixing with water
and begins to lose its plasticity. And the time that cement completely loses its
plasticity by mixing with water and begins to have a certain structural strength is
known as the final setting
time.
→ The national standards
prescribe that the initial
setting time of Portland
cement should not be
earlier than 45 minutes
and the final setting time
 should not be later than 6.5 hours.
→ The setting time of cement is measured by time determinator. The sample is the
standard cement paste of which the temperature is 20°C±3°C and humidity is more
than 90%. The finer the cement is ground, the more water the normal consistency
will need. The normal consistency of Portland cement is within 24%-30%.

D. FALSE SET
→ False set of portland cement is a stiffening of a concrete mixture with little evidence
of significant heat generation. To restore plasticity, all that is required is further mixing
without additional water.
→ It is when the cement starts to harden too quickly and clump together, which can
make the concrete weaker and less durable.

E. COMPRESSIVE STRENGTH TESTS

→ The measured maximum resistance to axial loading
→ Unit: pounds/sq. inch (psi)
→ Tested for 28 days, evaluated on ASTM criteria
𝐏 𝐅𝐨𝐫𝐜𝐞
𝐬= 𝐨𝐫: 𝐜𝐨𝐦𝐩𝐫𝐞𝐬𝐬𝐢𝐯𝐞 𝐬𝐭𝐫𝐞𝐧𝐠𝐭𝐡 =
𝐀 𝐀𝐫𝐞𝐚
→ Compression Testing Machine:

NON-DESTRUCTIVE METHODS
✓ Rebound Hammer
✓ Ultrasonic Pulse Velocity
✓ Penetration Probe
✓ Pullout
F. HEAT OF HYDRATION
→ Recall: Cement is hydrated to have adhesive properties
→ It is the amount of temperature liberated after water is mixed with the cement
mixture.
→ Why do we need to control it?
✓ It can be a factor for cracking.
▪ Temperature is not uniform among large
applications of concrete, leading to differences
in the outer and inner layers of the concrete.
→ Measured by a calorimeter.
→ Formula:
for Unhydrated Cement
𝐑𝐂
𝐇𝟏 = ( ) − 𝟎. 𝟐(∆𝐓)
𝐖𝐢
for Hydrated Cement
𝐑𝐂
𝐇𝟏 = ( ) − 𝟎. 𝟒(∆𝐓)
𝐖𝐢

G. LOSS OF IGNITION
→ Heating up a cement sample to 900 – 1000°C (1650 – 1830°F) until a constant
weight is obtained.
→ Weight loss is then measured.
→ Importance: Know the water content of the cement mixture and determine its quality.

H. RELATIVE DENSITY
→ Density of an object relative to water.
→ From the results of Al-Baijat and Sarireh, 2019,
→ "The higher the density, the higher the compressive strength."
→ The specific gravity of portland cement is generally around 3.15.

HARMFUL INGREDIENTS OF CEMENT

INGREDIENTS
1. Lime (CaO) .......... 62%
2. Silica (SiO2) .......... 22%
3. Aluminca(Al2 u3) .......... 5%
4. Calcium sulphate (CaSo4) .......... 4%
5. Iron Oxide (Fe2 O3) .......... 3%
6. Magnescia (MgO) .......... 2%
 7. Sulphur .......... 1%
8. Alkalies .......... 1%
HEALTH EFFECTS
✓ Cement can cause ill health by skin contact, eye contact, or inhalation. Risk of
injury depends on duration and level of exposure and individual sensitivity.
✓ Hazardous materials in wet concrete include:
> alkaline compounds such as lime (calcium oxide) are corrosive to human
tissue.
> trace amounts of crystalline silica which is abrasive to the skin and can
damage lungs.
> trace amounts of chromium that can cause allergic reactions.
> hexavalent chromium can cause respiratory allergy.
SKIN CONTACT
✓ The hazards of wet cement are due to its caustic, abrasive, and drying properties.
Wet concrete contacting the skin for a short period and then thoroughly washed
off causes little irritation by redness, swelling and itching. Severe and chronic skin
problems such as cement burns can occur long after exposure and workers may
not be aware of them until after severe damage occurs.
ALLERGIC SKIN REACTION
✓ The hazards of wet cement are due to its caustic, abrasive, and drying properties.
Wet concrete contacting the skin for a short period and then thoroughly washed
off causes little irritation by redness, swelling and itching. Severe and chronic skin
problems such as cement burns can occur long after exposure and workers may
not be aware of them until after severe damage occurs.
EYE CONTACT
✓ Exposure to airborne dust may cause immediate or delayed irritation of the eyes.
Depending on the level of exposure, effects may range from redness to chemical
burns and blindness.
INHALATION
✓ Inhaling high levels of dust may occur when workers empty bags of cement. In
the short term, such exposure irritates the nose and throat and causes choking
and difficult breathing. Sanding, grinding, or cutting concrete can also release
large amounts of dust containing high levels of crystalline silica. Prolonged or
repeated exposure can lead to a disabling and often fatal lung disease called
silicosis. Some studies also indicate a link between crystalline silica exposure
and lung cancer.
FIRST AID
✓ Skin contaminated with wet or dry cement should be washed with cold running
water as soon as possible. Open sores or cuts should be thoroughly flushed and
covered with suitable dressings. Get medical attention if discomfort persists.
Contaminated eyes should be washed with cold tap water for at least 15 minutes
before the affected person is taken to hospital.
WEAR APPROPRIATE PPE
✓ Protect yourself by wearing appropriate personal protective equipment (PPE) for
the job such as eye protection, butyl or nitrile gloves and waterproof boots under
rubber or PVC overboots.
FIELD EXAMINATION OF CEMENT
Manufacturing Date of Cement
✓ With the passage of packing time of cement, the strength reduces. So, It is
important to check the manufacturing date of cement. Generally, cement must
be used before 90 days from the date of manufacturing.
Time of Cement Strength Reduction %
3 Months 20-30
6 Months 30-40
12 Months 30-40
Color of Cement
✓ The color of cement gives an indication of excess lime or clay and the degree of
burning. After checking the date of packing, now open the cement bag and take
a look at the cement inside the bag. The color of the cement should be light
greenish grey and it should be uniform in color.
Presence of Lumps
✓ Cement develops lumps due to the presence of moisture from the atmosphere.
Cement should be stored under specified condition so that water and moisture
should never be an option for best quality cement but it is not good to use the
cement that is affected with moisture for construction. Any bags that are delivered
to the site with lumps must be discarded.
✓ Open the bag and take a look at the cement, there should be no visible lumps.
Push your hand into the cement bag, there should be no lumps inside. Any bag
having lumps must be rejected.
Adulteration Test
✓ This test is done by sensing the cement with the fingers. Take a pinch of cement
and feel (rub) between the fingers. It should feel smooth when rubbed between
the fingers. If it looks rough, it means that the cement is adulterated with sand.
Temperature Test
✓ When you insert your hand in bag of cement, it should give you cool feeling. It
must be cold from the inside. If it is hot from the inside, it indicates that the
process of hydration is taking place.
Float Test
✓ This test involves throwing a handful of cement into a bucket filled with water.
Cement particles must float for some time before sinking.
Strength Test
✓ This test involves the preparation of blocks of cement of dimensions 25 mm × 25
mm and length of 200 mm. It is immersed in water for 7 days. After this it has
been put on 150 mm support and it has been loaded with a weight of about 340
N. If the block will show no failure, the cement is of good quality.
Set Test
✓ A thick paste of cement with water is made on a piece of glass plate and kept in
water for 24 hours. It should set and not crack.
✓ Take 100 grams of cement and make a hard paste. Prepare a cake with sharp
edges and pour on a glass plate. Dip this plate in water. Keep in mind that the
shape should not be messed up during settling. It should be able to set and gain
strength. Cement is also capable of setting under water which is called as
‘hydraulic cement'.
SHIPPING AND STORING OF PORTLAND CEMENT
Water/Moisture
Agglomeration/Powder Caking

Time Frame Strength Decrease

3 months 10%-20%
6 months 15%-30%
12 months 25%-40%

TOPIC 4 Portland Cement Concrete

WATER–CEMENT REACTION
When portland cement and water are combined, a chemical reaction known as hydration
occurs. After 28 days, the hydration response is considered complete. When cement and
water are mixed to create a paste, the combination eventually stiffens and hardens. This
process is known as setting.
 → The majority of Portland cements show initial set in around 3 hours and final set
in around 7 hours.
→ False set of portland cement is a hardening of a concrete mixture with little
evidence of significant heat generation.
→ In situations where a cement exhibits a flash set, further mixing will be ineffective
because the cement has hydrated.
→ Cement's compressive strengths are usually determined on standard 2-in. (50.8-
mm) cubes.
→ Neat paste is water, cement, and a standard laboratory sand used to standardize
tests.
→ The heat of hydration, which is produced when water and cement chemically
react, can be an important factor in the use of concrete.
Approximate amounts of heat generation during the first 7 days of curing using Type I
cement as the base are as follows:

Type I 100%
Type II 80–85%
Type III 150%
Type IV 40–60%
Type V 60–75%
 → Concrete has a poor tensile strength, which is only around 11 percent of
concrete’s compressive strength.
→ Steel used to reinforce concrete can be welded wire mesh, deformed reinforcing
bars, or cable tendons.
→ Plain reinforced concrete can be used for most construction.
→ Prestressed concrete requires the application of a load to the steel before
concrete placement.
→ Posttensioned concrete is versatile because the loads applied to the steel can
be changed according to actual conditions of structure loading.
MIXING WATER
Water is used:
✓ To wash aggregates
✓ As mixing water
✓ During the curing process
✓ To wash out mixers
→ The use of an impure water for aggregate washing may result in aggregate particles
being coated with silt, salts, or organic materials.
→ It is generally accepted that any potable water can be used as mixing water in the
manufacture of concrete. Duff Abrams found seawater having a 3.5 percent salt
content
adequate in
producing
concrete so
that some
waters used
in concrete
making are
not potable.
→ Generally, seawater containing 35,000 ppm of salt can be used in nonreinforced
concrete, which will exhibit higher early strength with a slight reduction in 28-day
strength. The reduction in 28-day strength is usually compensated for in the mix
design. Seawater has been used in reinforced concrete; however, if the steel does not
have sufficient cover or if the concrete is not watertight, the risk of corrosion is
increased greatly. Seawater should never be used in prestressed concrete.
→ Generally, mixing waters having common inorganic acid concentrations as high as
10,000 ppm have no adverse effects on concrete strength.
→ Industrial wastewater and sanitary sewage can be used in concretes. After sewage
passes through a good disposal system, the concentration of solids is usually too low
to have any significant effect on concrete. As with all questionable water sources, it
pays to run the comparative strength tests before using such waters in concrete
manufacturing.
→ Sugar in concentrations of as little as 0.03 to 0.15 percent by weight of cement will
usually retard the setting time of cement. There may be a reduction in 7-day strength
and an increase in 28-day strength.
→ Clay or fine particles can be tolerated in concentrations of up to 2000 ppm. Silty water
should settle in basins before use to reduce the suspended silts and clays.
→ Mineral oils have less effect on strength development than vegetable or animal oils;
however, when concentrations are greater than 2 percent by weight of cement, a
strength loss of approximately 20 percent or more will occur. Organic impurities such
as algae in mixing water may cause excessive strength reductions by affecting bond
or by excessive air entrainment. As with all of the ingredients used in concrete
production, if the water available is questionable, the comparative property tests
should be run.
→ Sometimes the concrete mix can be modified to compensate for water which produces
low strength or exhibits other adverse characteristics. The use of water containing
acids or organic substances should be questioned because of the possibility of surface
reactions or retardation. The other concern with curing water is the possibility of
staining or discoloration due to impurities in the water.
→ The choice of aggregates for a particular application depends on a variety of factors,
including the desired strength and durability of the concrete, the local availability and
cost of the materials, and the aesthetics of the finished product.
→ For example, natural sand is a common choice for fine aggregates, as it is readily
available and relatively inexpensive. Crushed stone and gravel, on the other hand, are
commonly used for coarse aggregates, as they provide good strength and durability,
and are often used in structural applications such as foundations, bridges, and
roadways.
→ Aggregates selected for use should be clean, hard, strong, and durable particles, free
of chemicals, coatings of clay, or other materials that will affect the bond of the cement
paste. Aggregates containing shale or other soft and porous organic particles should
be avoided because they have poor resistance to weathering. Coarse aggregates can
usually be inspected visually for weaknesses.
→ Aggregates must possess certain characteristics to produce a workable, strong,
durable, and economical concrete. These basic characteristics are shown in Table 4–
7.
RECYCLED CONCRETE MATERIALS
→ Recycled concrete material (RCM) is produced by the crushing of existing concrete
structures when they are demolished.
SOURCES FOR RECYCLED CONCRETE MATERIALS
✓ Construction sites.
✓ Structures that have overcome their age and limit.
✓ Debris of structures that were caused by natural disasters.
PROCEDURE FOR OBTAINING RECYCLED CONCRETE MATERIALS
✓ On site - Uses portable crushers and the crushed concrete produced usually
becomes backfill and base course material for on-site use.
✓ Central facility - The concrete processed at a central facility will normally be
graded, washed, and stockpiled as coarse and fine aggregate.
→ These recycled aggregates will be tested and evaluated for their potential use as
partial or complete substitutions for natural aggregates in portland cement concrete,
asphalt paving mixes, and subgrade material.
→ The use of recycled concrete aggregates may also help earn credit toward the U. S.
Green Building Council’s Leadership in Energy & Environmental Design (LEED)
Green Building Rating System, increasing the chance to obtain LEED project
certification.
→ The maximum sizes for coarse aggregates are usually based on the ACI 211.1
 NON-REINFORCED MEMBER
✓ One-fifth the minimum dimension of nonreinforced
members. With a minimum dimension of 15 in.

REINFORCED MEMBERS
✓ Three-fourths the spacing between reinforcing bars or
between reinforcing bars and the forms.

NONREINFORCED SLABS
✓ One-third the depth of nonrein-Forced slabs on grade.

Bulk unit weight - The weight of an aggregate per unit volume. The volume is occupied
by aggregates and voids.
→ A container of known volume is filled with aggregate following ASTM C29 methods
and then weighed to determine the aggregate’s bulk unit weight, or density in Pcf
or kg/m3.
→ The most common classification of aggregates on the basis of bulk specific gravity.

→ The specific gravity is not a measure of aggregate quality but is used to design and
control concrete mixes. The specific gravity is defined as the ratio of the solid unit
weight of a substance to the weight of an equal volume of water.
ADMIXTURES
→ The basic concrete mix design can be modified by the additional of an admixture.
Admixtures are defined as any material other than Portland cement, aggregates,
and water added to a concrete or mortar mix before or during mixing.
AGGREGATES MOISTURE CONDITION
✓ Total Moisture
✓ Surface Moisture
✓ Absorbed Moisture
✓ Wet weight- weight of solid material plus absorbed water filling the pores plus
some free water on the particle surface.
✓ Saturated, surface dry weight –weight of solid material plus enough absorbed
water to fill the pores.
✓ Air dry weight- weight of solid material plus some variables amount of water in
the pores.
 ✓ Oven dry weight- weight of solid materials only. This is the most consistent
weight because no water is include.
wet weight – oven dry weight
✓ 𝐓𝐨𝐭𝐚𝐥 𝐌𝐨𝐢𝐬𝐭𝐮𝐫𝐞 (%) = × 100
Oven dry weight
✓ 𝐀𝐛𝐬𝐨𝐫𝐛𝐞𝐝 𝐌𝐨𝐢𝐬𝐭𝐮𝐫𝐞 (%) =
Saturated surface dry weight – oven dry weight
= 100
Oven dry weight
✓ 𝐅𝐫𝐞𝐞 𝐌𝐨𝐢𝐬𝐭𝐮𝐫𝐞 (%) =
Total Moisture (%)– Absorbed Moisture(%)
ADMIXTURE ARE GENERALLY USED FOR ONE OR MORE OF THE FOLLOWING
REASONS
1. To improve workability of the fresh concrete.
2. To reduce water content, thereby increasing strength for a given water- cement
ratio.
3. To increase durability of the hardened cement.
4. To retard setting time or increase it.
5. To impart color to concrete.
6. To maintain volume stability by reducing or offsetting shrinkage during curing.
7. To increase concrete resistance to freezing and thawing.
→ Most admixture perform more than one function; for example, when an air –
entraining admixture is used, increased resistance to freeze-thaw cycle in the
hardened concrete, a reduction in bleed water, and increased workability in the
fresh concrete can be expected.
Table 4–10. Effect of production procedures, construction practices, and environment on
control of air content in concrete.

Type of Admixture Desired Effect Material

Calcium chloride (ASTM D 98
Accelerators (ASTM C 494
Accelerate setting and early- and AASHTO M 144)
and AASHTO M 194, Type
strength development. Triethanolamine, sodium
C)
thiocyanate, calcium formate,
 calcium nitrite, calcium
nitrate.
Tributyl phosphate, dibutyl
phthalate, octyl alcohol,
Air detrainers Decrease air content. water-insoluble esters of
carbonic and boric acid,
silicones.
Salts of wood resins (Vinsol
resin), some synthetic
detergents, salts of sulfonated
Improve durability in freeze–
Air-entraining admixtures lignin, salts of petroleum
thaw, deicers, sulfate, and
(ASTM C 260 and AASHTO acids, salts of proteinaceous
alkali-reactive environments.
M 154) material, fatty and resinous
Improve workability.
acids and their salts,
alkylbenzene sulfonates, salts
of sulfonated hydrocarbons
Barium salts, lithium nitrate,
Alkali-aggregate reactivity Reduce alkali-aggregate
lithium carbonate, lithium
inhibitors reactivity expansion.
hydroxide.
Cohesive concrete for
Antiwashout admixtures Cellulose, acrylic polymer
underwater placements.
Increase bond strength Polyvinyl chloride, polyvinyl
Bonding admixtures acetate, acrylics, butadiene-
styrene copolymers
Modified carbon black, iron
Coloring admixtures (ASTM oxide, phthalocyanine, umber,
Colored concrete
C 979) chromium oxide, titanium
oxide, cobalt blue
Calcium nitrite, sodium nitrite,
Reduce steel corrosion
sodium benzoate, certain
Corrosion inhibitors activity in a chloride-laden
phosphates or fluosilicates,
environment.
fluoaluminates, ester amines
Retard moisture penetration Soaps of calcium or
Dampproofing admixtures
into dry concrete ammonium stearate or oleate
Cationic and anionic
Produce lightweight, foamed
Foaming agents surfactants
concrete with low density
Hydrolized protein
Fungicides, germicides, Inhibit or control bacterial and Polyhalogenated phenols
and insecticides fungal growth Dieldrin emulsions
Cause expansion before
Gas formers Aluminum powder
setting
See Air-entraining
Adjust grout properties for admixtures,
Grouting admixtures
specific applications Accelerators, Retarders, and
Water reducers
 Suspend and reactivate Carboxylic acids
Hydration control
cement hydration with Phosphorus-containing
admixtures
stabilizer and activator organic acid salts
Latex
Permeability reducers Decrease permeability
Calcium stearate
Organic flocculents
Organic emulsions of paraffin,
coal tar, asphalt, acrylics
Pumping aids Improve pumpability
Bentonite and pyrogenic
silicas
Hydrated lime (ASTM C 141)
Lignin
Retarders (ASTM C 494 and Borax
Retard setting time
AASHTO M 194, Type B) Sugars
Tartaric acid and salts
Polyoxyalkylene alkyl ether
Shrinkage reducers Reduce drying shrinkage
Propylene glycol
Sulfonated melamine
formaldehyde condensates
Increase flowability of
Superplasticizers* (ASTM C Sulfonated naphthalene
concrete.
1017, Type 1) formaldehyde condensates
Reduce water-cement ratio
Lignosulfonates
Polycarboxylates
Superplasticizer* and Increase flowability with
See superplasticizers and
retarder (ASTM C 1017, retarded set.
also water reducers
Type 2) Reduce water–cement ratio
Lignosulfonates
Water reducer (ASTM C Hydroxylated carboxylic acids
Reduce water content at least
494, and AASHTO M 194, Carbohydrates
5%
Type A) (Also tend to retard set so
accelerator is often added)
Water reducer and
Reduce water content
accelerator (ASTM C 494 See water reducer, Type A
(minimum 5%) and accelerate
and AASHTO M 194, Type (accelerator is added)
set
E)
Water reducer and retarder
Reduce water content See water reducer, Type A
(ASTM C 494 and AASHTO
(minimum 5%) and retard set (retarder is added)
M 194, Type D)
Water reducer—high range
Reduce water content
(ASTM C 494 and AASHTO See superplasticizers
(minimum 12%)
M 194, Type F)
Water reducer—high
Reduce water content See superplasticizers and
range—and retarder (ASTM
(minimum 12%) and retard also water
C 494 and AASHTO M 194,
set reducers
Type G)
 Reduce water content
Lignosulfonates
Water reducer—mid range (between 6 and 12%) without
Polycarboxylates
retarding
Table 4–10. Effect of production procedures, construction practices, and environment on
control of air content in concrete.
Procedure/Variable Effects Guidance
Simultaneous batching lowers
air content. Add air-entraining admixture
Batching sequence
Cement-first raises air with initial water or on sand.
content.
Air increases as capacity is Run mixer close to full
Mixer capacity
approached. capacity. Avoid overloading.
Central mixers: air content
Establish optimum mixing
increases up to 90 sec. of
time for particular mixer.
mixing.
Truck mixers: air content
Avoid overmixing.
Mixing time increases with mixing.
Short mixing periods (30
seconds) reduce air content Establish optimum mixing
and adversely affect air-void time (about 60 seconds).
system.
Avoid manual-dispensing or
gravity-feed systems and
Accuracy and reliability of
timers. Positive-displacement
Admixture metering metering system will affect
pumps interlocked with
uniformity of air content.
batching system are
preferred.
Some air (1 to 2%) normally Normal retempering with
lost during water to restore slump will
transport. restore air.
If necessary, retemper with
Transport and Loss of air in nonagitating
air-entraining admixture
delivery equipment is slightly higher.
to restore air.
Dramatic loss in air may be
due to factors other than
transport.
Optimize delivery schedules.
Long hauls, even without
Maintain concrete
Haul time and agitation agitation reduce air,
temperature in recommended
especially in hot weather.
range.
Retemper only enough to
restore workability.
Regains some of the lost air.
Avoid addition of excess
Retempering
water.
Does not usually affect the
air-void system.
 Retempering with air- Higher admixture dosage is
entraining ad mixtures needed for jobsite admixture
restores the air-void system. additions.
Reduces air content by an Avoid long conveyed distance
average of 1%. if possible.
Belt conveyors
Reduce the free-falling effect
at the end of conveyor.
Use of proper mix design
Reduction in air content
provides a stable air-void
ranges from 2 to 3%.
system.
Does not significantly affect Avoid high slump, higher air
Pumping air-void system. content concrete.
Keep pumping pressure as
low as possible.
Minimum effect on freeze– Use loop in descending pump
thaw resistance. line.
Generally, reduces air content Air content of mix should be
Shotcrete
in wet-process shotcrete. at high end of target zone.
Do not overvibrate. Avoid
Air content decreases under high-frequency vibrators
prolonged vibration or at high (greater than 10,000 vpm).
frequencies. Avoid multiple passes
Internal vibration
of vibratory screeds.
Closely spaced vibrator
Proper vibration does not
insertion is recommended for
influence the air-void system.
better consolidation.
Air content reduced in surface Avoid finishing with bleed
Finishing
layer by excessive finishing. water still on surface.
Avoid over finishing. Do not
sprinkle water on surface
prior to finishing. Do not steel
trowel exterior slabs.
Increase air-entraining
Air content decreases with
admixture dosage as
increase in temperature
temperature increases.
Temperature
Changes in temperature do
not significantly affect spacing
factors.

50-500 MICRONS
→ The size of the effective air voids in which the largest and smallest voids having
little effect in protecting the paste.
AIR-ENTRAINING ADMIXTURES
→ The water content may be decreased 0.3 to 4 lb per 1% of air with the same
workability due to the ball bearing action of the air voids.
→ Otherwise, a decrease in compressive strength of 3% to 5% for each 1% of air
entrained will result.
ACCELERATION OF SETTING TIME OF CONCRETE
→ Soluble Chlorides
→ Carbonates
→ Silicates
→ Calcium Chloride
CALCIUM CHLORIDE
✓ most widely used
✓ general dosage should not exceed 2% by weight of cement.
✓ should not be used in prestressed concrete because of corrosion.
✓ used during the winter to speed up initial setting time to allow earlier
finishing.
✓ not an antifreeze and does not substantially lower freezing
temperatures of the concrete.
✓ get the concrete through its early
RETARDER
✓ used for concrete placements during warm weather.
✓ primarily organic compounds such as lignosulfonic acid salts or
hydroxylated carboxylic acid salts
✓ during warm weather it helps to offset the decreased setting time due
to higher placement temperatures
SUPERPLASTICIZERS OR HIGH-RANGE WATER REDUCERS
✓ chemical dispersants that, when added to a concrete mix with a 3 to 3
1/2-in. slump, can increase the slump to 8 to 10 in. depending on the
dosage rate and other mix components.
✓ used to solve difficult placement problems such as tight constricted
formwork, dense rebar configurations, and situations where the
concrete must be pumped, conveyored, or chuted over long distances.
MICROSILICA OR SILICA FUME
✓ by-product of the silicon and ferrosilicon industries
✓ its chemical makeup is similar to fly ash and portland cement in that all
three contain the same basic chemical compounds.
✓ physical characteristics includes average diameters of particles
with100 times finer than cement, the specific gravity is 2.2 versus a
common 3.15 for cement, and the bulk density is 9 to 25 pcf versus 94
pcf for portland cement.
TWO PRODUCTS IN HYDRATION PROCESS
1. Calcium Silicate Hydrate: the glue or binder of the system.
2. Nonbinder Calcium Hydroxide: when present in large quantities, may
make the concrete more vulnerable to chemical and sulfate attack as well
as to adverse alkali-aggregate reactions.
ASTM C618
→ standard specification that governs the use of fly ash, a by-product of the
combustion of powdered coal as a mineral admixture.
→ Class F fly ash is describe as the by-product of burning anthracite or bituminous
coal and as having pozzolanic properties.
→ Class C, produced from the burning of lignite or subbituminous coal, has both
pozzolanic and some cementitious properties.
 HIGH VOLUME FLY ASH CONCRETE (HVFAC)
→ These are new concrete mixes from concrete specifications which have usually
limited the fly ash substitution by weight for portland cement to a range of 15%
to 25% maximum; with the easing of these restrictions, replacement values as
high as 50% are successfully being used on concrete construction projects.
→ When concrete is manufactured with the addition of fly ash, its placeability,
workability, and pumpability increase because of the ball bearing effect of the
microscopic ash particles. Concrete with fly ash will normally take longer to set,
thus extending the finishing time, and overall will take longer to reach the desired
compressive strength. Because the required strengths are not usually reached at
28 days, it is advisable to prepare enough test specimens to allow for testing at
later ages up to 56 days.
PROPORTIONING CONCRETE INGREDIENTS
→ Duff Abrams published his initial research on the water–cement ratio (w/cm) concept in
1918, indicating that the ratio of water to cement was related to concrete strength.
→ The weight of the water in the mix divided by the weight of the cementitious materials that
go into the mix.
PROPORTIONING CONCRETE INGREDIENTS
✓ Proportioning of concrete mixes is called mix design and is based on empirical
information and test.
✓ Lower water–cement ratios reduce the permeability and improve the durability of
concrete.
✓ Proportioning may vary from the simple 1:2:3 formula, which means 1 part cement, 2
parts fine aggregate, and 3 parts coarse aggregate, to the ACI 211.1 mix design
procedure, which is included in the Appendix.
✓ Concrete strength is inversely proportional to the water–cement ratio, a reduction in
water while maintaining cement content will give an increase in strength.
✓ A rule of thumb for good concrete of 0.45 to 0.58 water–cement ratio states that each
0.01 reduction in the water–cement ratio will increase 28-day strength by 100 psi.
✓ In higher-strength concretes, the use of a water reducer is required because of the
low water–cement ratio being used (0.30 to 0.35). If concrete of this water–cement
ratio is to be workable, a water reducer is required to raise the workability of such a
mix.
✓ The mix design must satisfy service requirements, and factors such as mixing,
handling, transportation, curing, and strength requirements must be considered.
✓ The workability of fresh concrete is important and must consider maximum aggregate
sizes, water content, and finishing.
✓ Trial batches are produced and tested before actual production of concrete begins.
✓ Concrete proportioning can be done by trial batching or past experience.
✓ A widely used method for mix designs is ACI 211.1, Recommended Practice for
Designing Normal and Heavy-weight Concrete.
A. Batching, Mixing, Transporting and Handling of concrete
Batching of Materials
> For good quality concrete a proper and accurate quantity of all the
ingredients should be used. The aggregates, cement and water should
be measured with an accuracy of ± 3 per cent of batch quantity and
the admixtures by 5 per cent of the batch quantity.
 > Volume Batching - Volume batching is generally recommended for
small jobs only. The amount of each solid ingredient is measured by
loose volume using standard box known as gauge box.
> Weigh Batching- For smaller works manual batching is done. All the
operations of weighing and batching of the ingredients are done
manually. The weighing may also be done by ordinary platform
weighing machines. For large size works weigh bucket equipments are
used. The weigh buckets are fed from hoppers and these discharge
the ingredients by gravity, straight into the mixer.
Mixing
> The object of mixing is to make the concrete mass homogeneous and
uniform in color and consistency. All the aggregate particles should
have a coat of cement paste and all the ingredients of the concrete
should blend into a uniform mass.
> Hand Mixing - Hand mixing is done over an impervious floor.
Measured quantities of coarse aggregate and fine aggregate are
spread over the floor in alternate layers. Then cement is poured over it
and the ingredients are mixed dry with shovel until uniformity in colour
is achieved. This mix is spread out in thickness of 200 mm and water
is sprinkled. The mix is kept on turning over till a uniform colour is
achieved.
> Machine Mixing - Mixers can be broadly classified as batch mixers
and continuous mixers. The batch mixers produce concrete batch by
batch with time interval, whereas continuous mixers produce concrete
continuously till plant is working. Batch mixers are used for small and
medium size works. Continuous mixers are used for large size works,
e.g., dams. The drum type may be further classified a:
o Tilting: 85T, 100T, 140T, 200T
o Non-tilting: 200NT, 280NT, 340NT, 400NT, 800NT
o Reversing: 200R, 280R, 340R, 400R.
> Tilting Mixers: The tilting mixers may be hand fed or loader (skip) fed.
The mixer is generally bowl shaped or double conical frustum type. It
can be tilted for discharging concrete.
> Non-tilting mixers: It consists of a Non-tilting cylindrical drum with
blades inside and two circular openings at the two ends. The drum
rotates about a horizontal axis. The ingredients are fed from one
opening and the mix discharged from the other opening at the other
end by at inclined chute. The drawback is the segregation that occurs
owing to slow rate of discharge.
> Reversing Drum Mixer: These are also known as forced action type
mixers and are used for large size works. It consist of a horizontal non-
tilting type drum. It has two sets of blades. One set of blades mixes the
mix while drum is rotated in one direction. The second set of blades
discharges the mix when the drum is reversed.
> Pan-type or Stirring Mixer: These are non-mobile mixers and are
used either as a central mixing plat or at precast concrete factory.
Primarily these are used for making mortar but are also used efficiently
 for stiff and cohesive mixes. The rollers and blades rotate in a rolling
pan.
> Transit Mixer: Truck mounted mixers are also known as transit mixers
are very popular and have replaced the dumpers and agitator cars
used earlier to transport fresh concrete from the batching plant to the
site.
A. TRANSPORTING AND HANDLING OF CONCRETE
✓ Concrete should be transported to the place of deposition at the earliest without
the loss of homogeneity obtained at the time of mixing. A maximum of 2 hours
from the time of mixing is permitted if trucks with agitator and 1 hour if trucks
without agitators are used for transporting concrete.
MORTAR PAN
> This is the most common method of transporting concrete. This is
labor intensive method wherein the pans are passed from hand to
hand and is slow and expensive method.
WHEELBARROW
> Wheelbarrows are used for transporting concrete to be placed at
ground level. These are used for concreting rigid payments. For
long hauls due to uneven ground surface segregation may take
place.
CHUTES
> Chutes are used to transport concrete below the ground levels.
These are made with metal sheets with a slope more than IV: 2.5H
to ensure that unloaded concrete slides easily without
segregation.
DUMPER
> Dumpers, lorries or, trucks are used economically for hauls up to
5 km. Dumpers are usually of capacity 2 to 3 cu m whereas trucks
are of 4 cu m capacity. For long hauls agitators are used to
prevent segregation.
BUCKET AND ROPEWAY
> These are used when concreting is to be done in a valley or for
construction work of piers, dams etc. The bucket is brought close
to the mix site, filled and moved over ropeway to the site of
deposition.
BELT CONVEYOR
> The use of belt conveyors for transporting concrete is very little.
The two main objections are segregation and drying and stiffening
of concrete.
SKIP AND HOIST
> This is the most useful and advantageous method of transporting
concrete for multistorey buildings.
PUMPING
> Pumping of concrete is done for multistorey buildings, tunnels,
and bridges. The concrete is fed from the hopper into the pump
cylinder largely by gravity, assisted by the vacuum created on the
suction stroke of the piston and forced into the pipe line on the
pressure stroke.
B. PLACING AND FINISHING OF CONCRETE
PLACING
To achieve quality concrete it should be placed with utmost care
securing the homogeneity achieved during mixing and the avoidance
of segregation in transporting.
> Foundations: Concrete foundations for walls and columns are
provided below the ground surface. Before placing the concrete in
the foundation all the loose earth, roots of trees etc., are removed.
> Beams, Columns, and Slabs: . They should be adequately rigid
to withstand the weight of concrete and construction loads without
undue deformation. Forms should be light enough to avoid any
loss of mortar resulting in honeycombed concrete.
> Mass Concreting: When the concrete is to be laid in mass as for
raft foundation, dam, bridge, pier etc., concrete is placed in layers
of 350–450 mm thickness.
> Concreting Highways and Runways: Concrete is laid in bays for
highway, runway, or floor slabs.
FINISHING
Concrete is basically used because of its high compressive strength.
However, the finish of the ultimate product is not that pleasant.
> Formwork Finishes: A variety of looks can be had to the
architects imagination. By careful preparation of formwork,
proper mix design and good workmanship smooth surfaces
can be achieved. Prefabrication units can be produced to a
fine finish.
> Surface Treatments: The type of surface treatment
depends upon the purpose for which the concrete surface is
to be used. For example a pavement surface should be plane
but with sufficient roughness to exhibit skid resistance.
> Applied Finishes: The concrete surface is roughened,
cleaned and wetted. Over this a cement mortar of ratio 1:3 is
applied. This mortar rendering can be given a number of
surface finishes such as sand facing, rough cast finish,
pebble dash etc.
C. CONSISTENCY OF FRESH CONCRETE
A major requirement of fresh concrete is consistency, denoted by the fluidity
of the concrete as measured by the Slump test. If the slump of a concrete mix is
controlled, the consistency and workability necessary for proper placement and
indirectly the water–cement ratio can be controlled. Changes in water content have a
pronounced effect on slump.
The ASTM C143 test for slump of Portland cement concrete details the
procedure for performing Slump tests on fresh concrete.
D. DEPOSITING CONCRETE UNDERWATER
Depositing concrete under water is a technique used in construction to place
concrete in areas where water is present, such as in building structures like dams,
bridges, or underwater tunnels.
 The process involves using special equipment to place the concrete mixture
in a way that it stays cohesive and doesn't wash away or mix with the surrounding
water.
DUMP BUCKET PLACING
✓ Concrete may be placed underwater with the help of bottom dump buckets.
The concrete is taken through the water in water-tight bucket. On reaching
the place of deposition the bottom of the bucket is made to open and the
concrete is dumped.
BAGGED CONCRETE UNDERWATER PLACEMENT
✓ Another way of concreting underwater is by filling a cement bag with dry or
semi-dry mix of cement and aggregates and lowering them to the place of
deposition.
TREMIE METHOD
✓ The best method of placing concrete underwater is by the use of tremie pipe.
The concrete is poured into it through funnel. The bottom end of the pipe is
closed with a thick polythene sheet, with the bottom end of the pipe at the
place of deposition.
CONCRETE ESTIMATING
→ Concrete estimating involves calculating the amount of concrete needed for a particular
construction project.
→ Determining concrete quantities for a construction project requires volumetric calculations
because concrete is estimated and purchased by the cubic yard or cubic meter. The
contractor completes these volumetric calculations and adds an appropriate WASTE
FACTOR to the calculated quantities. Typical waste factors for concrete construction range
from 3 to 8 percent, with lower values used for formed placements and higher values used
for slab on grade projects.
→ Sample Problem #1:
A concrete slab is 12 feet
wide, 20 feet long, and 6
inches thick. What is the
total amount of concrete
needed, including a 5%
waste factor? (1 cu yd = 27
cu ft).

Solution:
First, we need to convert the thickness of the slab from inches to feet:
Thickness = 6 inches / 12 = 0.5 feet
Next, we can calculate the volume of the slab in cubic feet:
Volume = Length x Width x Thickness
Volume = 20 feet x 12 feet x 0.5 feet
Volume = 120 cubic feet
TOPIC 5 Production of Portland Cement Concrete
TESTING HARDENED CONCRETE
→ STRENGTH TEST OF HARDENED CONCRETE
COMPRESSIVE STRENGTH TESTS
→ Compressive Strength is the measured maximum resistance to axial loading,
expressed as force per unit of cross-sectional area in pounds per square inch
(psi).

→ ASTM C31 - Standard Practice for Making and Curing Concrete Test Specimens
in the Field.
→ ASTM C470 - Standard Specification for Molds For Forming Concrete Test
Cylinders Vertically.

Molds: 6 in. test cylinders:

• waxed cardboard • filled in 3 equal layers
• plastic • each layer is rodded 25
times

→ Storing of specimens after casting: 60°F (16°C) to 80°F (27°C) up to 48 hours

→ Cylinders must be in an environment that is capable of controlling
temperature, as well as, preventing moisture loss.
For specified strengths, 6000 psi (40 MPa) or greater, temperature range will be:
✓ Initial Curing: 68°F (20°C) to 78°F (26°C)
✓ Final Curing: 73+3°F or 73-3°F (23+2°C or 23-3°C)
Final curing
✓ Must begin with 30 minutes of mold removal.
✓ Performed in a moist curing room at 100 percent relative humidity or in
water saturated with calcium hydroxide.
✓ Cylinders must not be moved until at least 8 hours after final set, and must
be protected from jarring, freezing, or moisture loss.
✓ Transportation time: not exceeding 4 hours.
✓ Time taken for the strength of cylinders: 7 and 28 days.
→ ASTM C1232 - Standard Practice for Use of Unbonded Caps in Determination of
Compressive Strength of Hardened Concrete Cylinders.
→ ASTM C617 - Standard Practice for Capping Cylindrical Concrete Specimens
→ Unbonded cap is defined as a metal retaining ring with and elastomeric pad
insert of a specified Shore A Durometer hardness.
 → Record cylinders are the specimens under controlled curing conditions and are
generally used to judge the quality of the concrete for the job.
→ ASTM C94 - Standard Specification for Ready-Mixed Concrete
→ ACI 318 - Building Code Requirements for Structural Concrete and Commentary
→ Strength test is defined as the average strength of two 6 x 12 in. cylinders or
three 4 x 8 in. cylinders.
𝐚𝐯𝐞𝐫𝐚𝐠𝐞 𝐬𝐭𝐫𝐞𝐧𝐠𝐭𝐡 𝐨𝐟 𝐚𝐧𝐲 𝐭𝐡𝐫𝐞𝐞 𝐜𝐨𝐧𝐬𝐞𝐜𝐮𝐭𝐢𝐯𝐞 𝐭𝐞𝐬𝐭 ≥ 𝐬𝐩𝐞𝐜𝐢𝐟𝐢𝐞𝐝 𝐬𝐭𝐫𝐞𝐧𝐠𝐭𝐡
 → Whatever the value of the standard deviation, vertical lines drawn at one, two,
and three standard deviations on either side of the mean always include the same
proportion of area under the curve.
→ Coefficient of Variation is the statistical measure of the uniformity of concrete
production and testing.

SPLITTING TENSILE STRENGTH TESTS

→ ASTM C496 - Standard Test Method for Splitting Tensile Strength of Cylindrical
Concrete Specimens.

FLEXURE STRENGTH TESTS

 → ASTM C78 - Standard Test Method for Flexure Strength of Concrete (Using Simple
Beam with Third-Point Loading)

REQUIRED COMPRESSIVE STRENGTH

→ DENSITY, RELATIVE DENSITY, ABSORPTION AND VOIDS

DENSITY OF CONCRETE:
 ✓ Normal weight concrete: 2200-2500 kg/m^3
✓ Lightweight: 1600-4000 kg/m^3
RELATIVE DENSITY OF CONCRETE: 2.3-2.5
ABSORPTION OF CONCRETE: 5%-10% of its weight
VOIDS IN CONCRETE: depends on various factors such as the water-cement ratio,
aggregate grading, and curing conditions.
→ PERMEABILITY AND WATER TIGHTNESS
PERMEABILITY OF CONCRETE: depends on the pore structure of the concrete which is
determined by the water-cement ratio, the porosity of the aggregates, and the degree of
compaction.
✓ High permeability: lead to the ingress of water, cause of corrosion of
reinforcement, reduction in strength, and durability issues
WATER TIGHTNESS OF CONCRETE:
✓ Concrete can be made water-tight by reducing its permeability through the use
of various techniques such as reducing the water-cement ratio, adding water-
reducing admixtures, using pozzolanic materials, and adding waterproofing
agents.
✓ Proper curing and surface treatment can also help in making concrete water-tight.
→ NONDESTRUCTIVE TEST METHODS
→ The need to determine the in-place strength of concrete frequently occurs in the
construction industry.
→ Non-destructive concrete testing evaluates the solidity and grade of concrete
without inducing any damage to the structure.
THE MOST WIDELY USED IN-PLACE TEST METHODS ARE AS FOLLOWS:
1. The rebound hammer
A rebound hammer test on concrete is an appropriate strategy to specify
concrete’s compressive potency. It is commonly beneficial to test concrete
beams and cores,
which are also
used to assess the
quality of concrete.

2. The penetration
probe
The penetration resistance test is used to
determine the uniformity of concrete,
specify the poor quality or deteriorated
concrete zones, and evaluate the in-place
strength of concrete.

3. Pullouts
pullout test produces a well-defined concrete and
measures a static strength property of concrete. The
equipment is simple to assemble and operate.
4. Ultrasonic
the basic principle of ultrasonic testing is using sound
to inspect a material's thickness at different points.
→ EVALUATION OF COMPRESSION TEST RESULT
→ Compression test results ensure that the concrete mixture, as delivered, meets
the requirements of the specified strength, ƒ ́c, in the job specification.
→ The average of 3 consecutive tests should equal or exceed the specified
strength, ƒ ́c.
→ No single strength test should fall below ƒ ́c by more than 500 psi (3.5 MPa); or
by more than 0.10 ƒ ́c when ƒ ́c is more than 5000 psi (35 MPa).
→ When evaluating the compression test results, it is important to consider the
following factors:
✓ sample preparation
✓ testing procedure
✓ age of concrete
✓ moisture content
✓ comparison with specification
→ CURING OF CONCRETE
→ Curing is the process of preventing the loss of moisture from the concrete while
maintaining a satisfactory temperature regime.
→ It plays an important role in the:
✓ strength development
✓ durability
✓ increase resistance to freeze-thaw
✓ improve water tightness
✓ wear resistance of concrete
THREE MAIN FUNCTIONS OF CURING:
1. Maintain mixing water in concrete during the early hardening process
> Ponding and immersion
 > Spraying and fogging
> Saturated wet coverings
2. Reduce the loss of mixing water from the surface of the concrete
> Covering concrete with impervious paper or plastic sheets
> Applying membrane-forming curing compounds
3. Accelerate the strength gain using heat and additional moisture.
> Live steam
> Heating coils
> Electrical heated forms or pads
CURING PERIOD
→ American Concrete Institute (ACI) Committee 301 recommends a minimum
curing period of at least 70% of concrete's strength.
✓ initial strength is developed
in the first 7 to 10 days.
✓ concrete develops strength
over 28 days of casting.
→ ACI Committee 308 recommends
the following minimum curing
periods:
DRYING SHRINKAGE
→ occurs when concrete is placed at an excess water content during curing period.
EFFECT OF CURING TEMPERATURE ON STRENGTH

HOT-WEATHER CONCRETING
→ the loss of moisture after placement is critical.
→ Methods to prevent moisture loss:
a. windscreens
b. fog misting systems
c. additional water
→ There is no way to predict with certainty when plastic shrinkage cracking will
occur.
• rate of evaporation exceeds 0.2 lb/sq ft/hour, precautionary measures are
almost mandatory.
• Cracking is possible if the rate of evaporation exceeds 0.1 lb/sq ft/hour.

COLD-WEATHER CONCRETING
→ requires the maintenance of internal
heat or the use of additional heat to
provide the proper curing
temperatures.
Internal Heat
✓ insulating blankets and straw
may be used.
External Heat
✓ may be supplied by salamanders,
space heaters, or live steam.
Carbonation
✓ affects the durability of concrete
structures.
 → STRENGTH AND PROPERTIES OF CONCRETE WITH AGE

BONDING NEW AND OLD CONCRETE

→ Bonding new and old concrete is a common technique used in construction and renovation
projects. It involves joining a new layer of concrete to an existing surface, typically to
repair or extend a structure.
→ Bonding increases the strength of the composite material. However, proper bond is not
always guaranteed. It must be ensured through proper surface preparation, material choice
and use, and curing. Ignoring one of these may result in the total loss of bond.
SURFACE PREPARATION
→ All damaged, loosened, or unbonded portions of existing concrete should be
removed through chipping and other mechanical methods.
→ The surface of the substrate should be free from dust, dirt, oil, grease, wax, paint,
and other foreign materials that can interfere the bonding process. This can be
achieve by the use of:
✓ Chipping hammers
✓ Wire brushing
✓ Wet sandblasting
✓ Waterblasting
→ ACI 503 recommends that all equipment supplying compressed air be equipped
with efficient oil and water traps to prevent surface contamination from the
compressed air supply.
→ Acid etching was once considered another way to prepare a surface, but
experience s Also, some cleaning acids contain chlorides that can start rebar
→ corrosion. Acid etching is not recommended unless no other means
→ of cleaning is possible. hows that this method is not as dependable as mechanical
methods (ACI 503R).
PATCHES
→ Patches are easier to make and more successful if they are made as soon as
practical, preferably when the concrete is still green.
→ The edges of the defective area should be chipped or cut straight and at right
angles to the surface, or slightly undercut to provide a key at the edge of the patch.
 → Whatever the method, no
featheredges should be
permitted. When chipping
around reinforcement leave
at least a 1-inch space
around each exposed bar.
Always leave rebar partially
embedded.
CONSTRUCTION JOINTS
→ Workers can prepare the
surface of construction
joints during the first concrete placement.
For horizontal construction joints, the top
surface of fresh concrete can be roughened
while still plastic.
→ Sometimes workers sprinkle or mix
retarders into the top layer of concrete.
Delaying the set allows the surface to be
roughened up to 48 hours after the pour.
→ For vertical construction joints, the concrete
surface is generally too smooth to permit
proper bonding. Stiff- wire brushing may be
sufficient if the concrete is less than 3 days
old. Otherwise bushhammering or sand or
waterblasting may be needed.

OVERLAYS
→ For bonded two-course floors, the surface of the partially set base course is
usually brushed with a coarse wire broom to remove laitance and score the
surface.
→ Then it should be wet cured for 3 days. Don’t use curing compounds as they can
interfere with bonding.
→ In existing pavements, the type of coarse aggregate usually dictates the least
costly way to prepare a surface.
→ Most agencies specify the surface cleaning method and minimum depth of
surface removal.
→ The Corps of Engineers requires removal of at least 1/4 inch from the surface
by scarification followed by high-pressure water flushing and air blowing. The
Portland Cement Association (PCA) recommends that the surface be scarified to
remove unsound concrete and cleaned by sandblasting or other means.
BONDING MEDIUM
→ A substance used to promote adhesion between concrete surfaces. Common
types of bonding mediums are bonding agents, admixtures, and roughening
agents.
→ The most practical and economical bonding agents are sand-cement and water-
cement grouts.
 → On the other hand, epoxy resin grouts specially formulated for each application
also are on the market.
SAND-CEMENT & WATER-CEMENT GROUTS
✓ inexpensive and readily available
✓ typically made by mixing sand or water with cement to create a thick,
paste-like substance
EPOXY RESIN GROUTS
✓ more expensive but has superior adhesion and durability
✓ made of epoxy resins and a hardener
SAND-CEMENT GROUTS
✓ The ratio of cement to sand normally varies from 1:1 to 1:2 as per
requirements. However, the recommended ratio of 1:1 (by volume) for
sand to cement is a common guideline that is often used for bonding
applications.
✓ The American Concrete Institute (ACI 213R-14) recommends a sand
cement ratio of 1:2.5 (by volume) which is 1 part cement to 2.5 parts
sand. The British Standards Institution (BS 4551:2005) also
recommends a sand cement ratio of 2:1 for general use and 3:1 for
heavy duty grouting.
WATER-CEMENT GROUTS
✓ The American Concrete Institute (ACI 213R-14) recommends a ratio
for general-purpose grouting is 0.35:1 (by weight), which means 0.35
parts of water to 1 part of cement.
EPOXY RESIN GROUTS
✓ The American Concrete Institute (ACI 503.4R-94) provides a recommended
ratio of epoxy resin to cement for grout mixtures of 1:1 which states 1 part
cement to 1 part epoxy resin by volume, which means equal parts of cement
and epoxy resin should be used in the mixture.
BONDING PROCEDURE
→ After preparing the surface, the contractor need only decide if the concrete should
be dry or damp before brooming or brushing the bonding medium into place. Most
agencies recommend a damp surface free of water, especially in hot, windy
weather.
→ Protect the bonding medium from drying above and below. Hot, windy weather
dries the bonding medium from above. From below, porous aggregates or
concrete can absorb enough water to prevent complete hydration. This produces
a weak bond interface, or the porous surface can absorb enough epoxy to starve
the glue line.
→ Apply the grout immediately before placing the new concrete. Place only as much
grout as can be covered with fresh concrete before the grout dries. The amount
of grout varies with weather, equipment, and crew. After applying the bonding
medium, place the concrete as usual.
CURING
→ Start curing as soon as possible after placing the fresh concrete. Use wet burlap,
wet sand, plastic sheets, curing paper, tarpaulins, curing compounds, or a
combination.
 → Moisture and temperature both affect the curing of bonded concrete. Differential
shrinkage, thermal movements, or moisture gradients can cause enough stress
to break the bond during the curing period.
→ This is especially important when the new concrete has different properties
(modulus of elasticity, coefficient of thermal expansion, shrinkage strains) than
the underlying concrete.
FORMS AND MOLDS FOR CONCRETE
→ Cement concrete is a mixture of cement, sand pebbles or crushed rock and water. When
placed in the skeleton of forms and allowed to cure, becomes hard like a stone.
CONCRETE FORMS
→ Concrete form refers to a temporary structure made of wood, metal, or other
materials that is used to create the desired shape and size of concrete during the
casting process. The formwork supports the weight of the wet concrete until it sets
and gains strength to stand on its own. The formwork also provides a finished surface
the concrete can bond to and keeps the concrete in place until it cures, ensuring
accurate and precise concrete work, especially in complex structures. Typically, the
formwork is removed once the concrete has dried and can stand on its own.
PAVER MOLD
✓ A mold used to create concrete pavers, also known as
stepping stones or patio blocks. These molds can be
rectangular or circular in shape and are used to make
aesthetically pleasing pieces that can be used in
landscaping or hardscaping projects.
PLANTER MOLD
✓ A mold used to create concrete planters, also known
as garden pots. These molds can be long or short
with various sizes and shapes to create unique and
interesting planters that are perfect for gardening or
landscaping projects.
RETAINING WALL MOLD
✓ A mold used to create concrete retaining walls
that are essential to control soil erosion,
landslides, and maintain a natural slope. These
molds can be large or small and can be used to
create walls of various heights, lengths, and
designs according to the specific needs of the
construction project.
COLUMN MOLD
✓ A mold used to create concrete columns that can be used
to add a decorative element to a home or building. These
molds can be tapered or cylindrical in shape and can be
used to create columns of various heights and diameters.
STATUARY MOLD
✓ A mold used to create concrete sculptures and figures.
These molds can be intricate and complex, creating
detailed statues and sculpture pieces that are perfect for
decoration, landscaping or interior design projects.
 CONCRETE FORMS
→ Molds of concrete refer to the frames or structures used to shape and set concrete
into a desired form. These molds can be made of various materials such as wood,
metal, or plastic and are usually designed according to the specific shape and size
of the concrete object being created. Concrete molds can range from simple DIY
projects such as flower pots or stepping stones to complex designs such as
architectural elements or large-scale sculptures. The molds are typically filled with a
concrete mix and allowed to dry or cure before the form is removed to reveal the final
product.
FLATWORK FORM
✓ Flatwork forms are used for constructing
horizontal surfaces such as floors, sidewalks,
patios, and driveways. These forms are typically
made of wood or metal and are available in
various shapes and sizes.
WALL FORM
✓ Wall forms are used to create vertical concrete
structures such as walls, columns, and beams.
These forms are made of plywood or steel sheets
and may be adjustable in size and shape for
customized designs.
SLIP FORM
✓ Slip forms are used for constructing tall and
slender structures such as chimneys, silos, and
towers. Slip forms are made of metal, steel, or
plywood and allow continuous pouring of
concrete.
STAY-IN-PLACE FORM
✓ Stay-in-place forms, also known as insulated
concrete forms (ICFs), are used to create
insulated and energy-efficient walls. These
forms are made of foam blocks or panels that
serve as both formwork and insulation.

PERFORMANCE CHARACTERISTIC OF CONCRETE

→ Concrete is a widely used construction material because of its durability and strength. The
performance characteristics of concrete depend on various factors such as the materials
used, mixture proportions, and curing methods.
Freeze-Thaw Durability
✓ Resistance to cycles of freezing and
thawing is important for structures
that can become critically saturated
and are exposed to a severe freeze-
thaw environment. Thus, it is only
important in regions experiencing
cycles of freezing and thawing.
 Without appropriate measures, cracking, scaling, and disintegration of the
concrete can occur.
Scaling Resistance
✓ The resistance to scaling is improved by
providing an adequate air-void system,
proper finishing and curing, a drying period
before the salt application, and reduced
permeability and water cementitious
materials ratios.
Abrasion Resistance
✓ The abrasion resistance is improved by increasing the
compressive strength, using hard and dense aggregates,
and proper finishing and curing methods.
Chloride Penetration
✓ The durability of concrete exposed outdoors depends
largely on its ability to resist the penetration of water
and aggressive solutions.
✓ All concretes exposed outdoors or cured in a moist
room exhibit a reduction in coulomb values with time,
and different concretes have different rates of
reduction.
Compressive Strength
✓ The capacity of concrete to withstand loads before failure. Of the many tests
applied to the concrete, the compressive strength
test is the most important, as it gives an idea about
the characteristics of the concrete.
✓ Concrete compressive strength can vary from
2500 psi (17 MPa) for residential concrete to 4000
psi (28 MPa) and higher in commercial structures.
Some applications use higher strengths, greater
than 10,000 psi (70 MPa).
Modulus of Elasticity
✓ Defined as the ratio of the applied stress to the
corresponding strain. Not only does it demonstrate
the ability of concrete to withstand deformation
due to applied stress but also its stiffness. In other
words, it reflects the ability of concrete to deflect
elastically.
Shrinkage
✓ Shortening that results from loss of moisture from
the concrete. The magnitude and rate of shrinkage
depend on many factors, including concrete
constituent materials, size of the member, amount
of nonprestressed reinforcement, and ambient
environment.
Creep
✓ The change in length of a concrete member when subjected to a sustained load.
The amount and rate of creep depend on concrete constituent materials, age and
 strength of concrete at time of load application, length of
time under load, size of the member, amount of
nonprestressed reinforcement, and ambient
environment.

CHB MANUFACTURE
CONCRETE HOLLOW BLOCKS (CHB)
→ Most commonly known as CHB are the main
components for concrete wall laying which is a
standard dimension of rectangular block used in
building construction.
→ One of the most extensively used walling materials in
the Philippines.
ADVANTAGES DISADVANTAGES
→ Strong and durable
→ Fire-resistant and Non-combustible
→ Complex installation process
→ Weather Resistant
→ Labor intensive
→ Cheap
→ Availability

TYPES OF CONCRETE HOLLOW BLOCKS

→ CHB 6" and CHB 4" are the common types of Concrete Hollow
→ Blocks available in the market.

THE PROCESS OF MANUFACTURE OF CEMENT CONCRETE HOLLOW BLOCKS

INVOLVES THE FOLLOWING 5 STAGES
1. PROPORTIONING
→ The determination of suitable amounts of raw materials needed to produce
concrete of desired quality under given conditions of mixing, placing and
curing is known as proportioning.
This is done in two different ways Weight and Volume
 Mix Proportion 1:7, as per structural engineer’s
Mixture
specification
Clean water should be used. Shall not exceed 28
liters per 40 kilograms per bag of cement, slump
Water
test (as per ASTM C-143) shall not exceed 10cm,
unless specified by a structural engineer.

Common CHB mix:

2. MIXING
→ The objective of the thorough mixing of aggregates, cement, and water is to
ensure that the cement-water paste completely covers the surface of the
aggregates.
→ All the raw materials including water are collected in a concrete mixer, which
is rotated for about 1 ½ minutes. The prepared mix is discharged from the
mixer and consumed within 30 minutes.
3. COMPACTING
→ The purpose of compacting is to fill all air pockets with concrete as a whole
without movement of free water through the concrete.
→ Ensure the formwork is clean before pouring and vibrate uniformly. The
concrete should be well compacted in order to make sure that any air which
is trapped in the concrete (weak points) is removed.
4. CURING
→ Hollow blocks removed from the mould box are protected until they are
sufficiently hardened to permit handling without damage.
→ The CHBs should be covered with a plastic sheet for at least 7 days in order
to effectively cure. This can be achieved by continually spraying them with
water or keeping them underwater in tanks. This leads to less cracking and
a stronger, harder, denser, and more durable concrete.
5. DRYING
→ Concrete shrinks slightly with loss of moisture.
→ After curing is over, the blocks should be allowed to dry out gradually in the
shade so that the initial drying shrinkage of the blocks is completed before
they are used in the construction work.

CONCRETE CONSTRUCTION PRACTICES

→ The base or formwork must be well prepared.
✓ The term 'formwork' refers to a temporary mould into which concrete is poured
and formed so that it can set to the required shape.
✓ The formwork sides must be capable of resisting the hydrostatic pressure of
the wet concrete.
✓ The formwork base or soffit must be capable of resisting the initial dead load
of the wet concrete and the dead load of the dry set concrete.
→ Adequate coverage must be provided for reinforcement.
✓ Concrete cover for reinforcement is required to protect the rebar against
corrosion and to provide resistance against fire.
 ✓ Concrete Cover Specifications as per ACI code:

→ Placement techniques must be such as to avoid segregation of concrete components.

✓ The design of concrete is very important to strength and durability, however,
attention should be placed on handling, placing, and curing to ensure uniform
quality throughout the mix.
Slip Forming - A method for the continuous placement and consolidation of
concrete.
Shotcrete - In this method concrete is applied by spraying it from a nozzle by
means of compressed air.
Tremie Concrete - This method is used for pouring concrete underwater or
placement in deep forms.
→ Consolidation techniques must be adequate to attain target densities.
✓ After placement, the concrete should be consolidated into the forms and around
reinforcing bars to eliminate trapped air and voids.
Concrete Vibrators - Basically, a vibrato applies periodic shear forces to the
concrete which causes the material to flow.
Vacuum Dewatering – A method of consolidation of horizontal surfaces which
removes water from the upper 12 inches of the slab, effectively consolidating the
material.
→ Finishing and curing techniques must be properly timed and adequate for environmental
conditions.
✓ Good finishing can provide a maintenance free surface and can offset some
deficiencies of a poorly designed mix.
Screeding – Excess concrete is struck off to bring the surface to the desired level
and fill any low spots.
Floating - This process compacts and removes imperfections from the surface
while forcing cement and water to the surface.
Trowelling – After floating, a surface may be steel-troweled to provide a really
smooth, dense, wear resistant surface.
Texturing - If a skid-resistant surface is desired, the freshly screeded surface
can be textured by scoring the surface with a wire or fiber broom. Excessive paste
can be removed with washing which results in an exposed aggregate finish.
Hardening - This treatment causes the surface to provide additional durability
and wear-resistance. This is the result of a chemical reaction with calcium
hydroxide in the paste creating more C-S-H.