CONCRETE TECHNOLOGY
(LAB)
MUHAMMAD IMTIAZ ASHRAF
INTERNATIONAL ISLAMIC UNIVERSITY ISLAMABAD
CONCRETE
Lecture # 1
By
Muhammad Imtiaz Ashraf
CONCRETE
Concrete is a composite material wherein a
binding material mixed in water, on
solidification binds the inert particles of well
graded fine and coarse aggregates
Wet or Green Concrete: Freshly prepared
concrete till it sets
Set Concrete: Concrete that has thoroughly set
and fully hardened
CONCRETE
Concrete is a composite manmade material that
consists of a mixture of ;
• binding material such as lime or cement
• well graded fine and coarse aggregates
• water
• admixtures (for special properties, etc)
CONCRETE
In a concrete mix, cement and water form a paste or
matrix which fills the voids of aggregate and binds
them together
Coarse aggregate acts as a filler.
Fine aggregate fills up the voids between the paste
and coarse aggregate.
Cement in conjunction with water acts as a binder.
Admixtures aid the mobility of the mixture by
regulating the setting environment and time.
CONCRETE CONSTITUENTS
Cement
Aggregates
Water
Admixtures
CEMENT
Cements in general are adhesive and cohesive
materials which are capable of bonding together
particles of solid matter into compact durable mass.
For civil engineering, cements containing
compounds of lime as chief constituent to bind the
fine and coarse aggregate particles together.
AGGREGATES
Inert materials mixed with a binding material
(cement, lime, mud) for preparation of mortar or
concrete.
Depending on the particle size, aggregates are
classified as
Fine aggregates: size 0.15 mm to 4.75 mm, sand,
crushed stone, ash, surkhi.
Coarse aggregates: size 4.75 mm to 7.5 cm.
MARGALLA QUARRIES
QUARRIES IN PUNJAB AND KPK
Quarry name in Quarry name in
Province Punjab Province KPK
Chiniot Takial
Margalla Khairabad
Sikhanwali
FINE AGGREGATE
Particle size 0.15 mm to 4.75 mm
Sand – small grains of silica from weathering,
disintegration of rocks
Pit or quarry sand – sharp and angular grains found as
deposits in soil. Free from organic matter and clay and
is of good quality
River sand – banks and beds of rivers. Needs washing
to get rid of clay
Sea sand – fine rounded brown grains at sea beaches.
Contains salts so needs washing
FINE AGGREGATE
Crushed stone – waste stone crushed to sand particle
size gives excellent fine aggregate
Surkhi – well ground, powdered broken brick used
as fine aggregate in lime mortar.
LAWRENCEPUR SAND DEPOSITS
COARSE AGGREGATE
Size from 4.75 mm to 7.5 mm
Stone ballast – quarried granite, sandstone and
limestone broken and sieved to required size.
Should be free from organic matter. Stone should
not be soft, laminated. Excess clay washed off.
Gravel or shingle – obtained from river beds,
quarries or sea shores. Hard and durable. Clay and
salts should be washed off.
COARSE AGGREGATE
COARSE AGGREGATE (PEBBLES & SHINGLES)
AGGREGATES IN CONCRETE
In Portland cement concrete, 60-75% of volume and
79-85% of the weight is made up of aggregates.
Aggregates have greater volume stability than
cement paste.
Therefore, maximizing the amount of aggregate, to
a certain extent, improves the quality and economy
of the mix.
AGGREGATE PROPERTIES
Aggregates properties are defined by characteristics
of both the individual particles and the
characteristics of the combined material.
These properties can be described by their physical,
chemical and mechanical characteristics
WATER
• Minimum quantity of water required for hydration
of cement
• Water in excess required to act lubricant between
aggregates to produce workable and economical
concrete
• Lesser water makes it difficult to work with
concrete and non-uniform mixing makes it weaker
in strength
• Water also required for curing and aggregate
washing
ADMIXTURES
Accelerate or retard the initial setting
Increase the strength
Improve workability, penetration and pumpability
Increase durability
Control expansion caused by reaction
Decrease capillary flow of water to make it
impermeable
Reduce segregation
Inhibit corrosion, increase resistance to chemical attack
THE END
