REPORT OF CIVIL ENGINEERING
MATERIALS PROJECT:
TOPIC: CONCRETE AND ADMIXTURES
GROUP MEMBERS:
HUSSAIN RAZA (23CE024)
FARMAN (23CE048)
UZAIR KHAN (23CE104)
ALLAH DINO (23CE164)
INTRODUCTION:
Concrete is a very important material in civil engineering, as it is
used for building structures such as bridges, dams, roads,
buildings, and more. Concrete is made of four basic ingredients:
cement, water, sand, and gravel sometimes admixtures are
added to made its properties modified. It is the man made
material sometimes also called artificial stone most widely used in
construction industry. freshly mixed concrete before set is known
as green concrete whereas after setting and hardening it is called
hardened concrete.
IMPORTANCE OF CONCRETE IN CIVIL
ENGINEERING:
Concrete is the most widely used material in construction side as
it is used to bind and hold the material together the reason
concrete has significance in civil engineering due to many
reasons which are listed below such as:
It is strong and durable, and can resist various
environmental factors, such as temperature, moisture, fire,
and corrosion.
It is versatile and can be molded into different shapes and
sizes, depending on the design and purpose of the structure.
It is economical and widely available, as the ingredients are
relatively cheap and easy to obtain. It is seen that instead of
natural stone concrete is used as artificial stone.
It is sustainable and environmentally friendly, as it can be
recycled and reused, and can also reduce the carbon
footprint of buildings.
It is sustainable and environment friendly.
It also reduces the carbon footprint of construction by
sequestering carbon dioxide during the curing process.
INGREDIENTS OF CONCRETE:
Concrete is a composite material made by mixing different
materials like cement, sand, aggregate, water, and sometimes
admixtures. The ingredients of concrete have different roles and
properties that affect the final product.
1. CEMENT: It is the main binder material that holds the
other ingredients together. It is composed of alumina, silica,
lime, iron, and gypsum. Cement hardens when mixed with
water through a chemical reaction called hydration. Cement
is the main binding agent in concrete that is taken with
lowest volume because it is costly. Cement is the main
binding agent in concrete that is taken with lowest volume
because it is costly.
2. WATER: It is the key ingredient that activates the hydration
process and forms a paste with cement. The amount of
water relative to cement changes the workability and
strength of the concrete. More water makes the concrete
easier to flow, but also weaker when cured.
The quality of water should be fresh, clean and free from
contamination such as alkalis that can interfere the setting and
hardening of cement or cause corrrosion of the reinforcement. A
higher water cement ratio results in lower strength and a high
permeability, workability and a lower risk of cracking. Standard
form of water cement ratio ranges from 0.45-0.55.
3. Aggregate: It is the bulk of the concrete mixture that
provides density and strength. Aggregates can be divided
into coarse aggregate(gravel or crused stone) and that
should be angular, round and smooth to produce bulk
means provide good bonding with the cement paste its size
and its size should ranges between 16mm-20mm for
foundation it is 6mm, while the other one is fine aggregate
(sand). The quantity of sand is added more because its
volume increases when 3 to 4% it gets. The size, shape, and
quality of the aggregate affect the durability and performance
of the concrete.
Air is the entrained gas that occupies the spaces between
the solid particles. The amount of air in the concrete mixture
ranges from 1% to 9%, depending on the exposure
conditions and desired properties. More air improves the
resistance to freezing and thawing, but also reduces the
strength and density of the concrete.
4. Admixtures: they are optional ingredients that are added
to modify or enhance the properties of the concrete. They
can be used to change the color, setting time, workability,
strength, durability, or performance of the concrete under
different conditions.
PROPERTIES OF ADMIXTURES:
To reduce the cost of concrete construction.
To speed up the rate of development of strength of concrete
at initial stage.
Increases the strength of concrete
To modify the properties of hardened concrete such as
improve workability, durability, dispersion and air
entertainment and reduce heat of hydration.
Resistance to freezing and thawing.
Control expansion caused by aggregates
It reduces segregation occurred in grouts, strengthen the
bond between old and new concrete surface.
QUALITY CONRTOL AND BUDGETING OF
CONCRETE:
Cost analysis and budgeting of any concrete project is a very
important task that requires careful planning and estimation. Cost
analysis is the process of calculating the total cost of a concrete
project that inculdes the cost of every materials, labor, equipment,
overhead, permits, fees, taxes and contingencies. There are
different methods and tools that can help you with cost analysis
and budgeting of any concrete project such as: bottom up
estimating, top down estimating, three point estimating analogous
estimating and expert judgement.
TESTING OF CONCRETE:
Testing of concrete is a process of evaluating the properties and
quality of concrete materials and structures. There are different
types of tests that can be performed on concrete, depending on
the purpose and application of the concrete. Some of the common
tests on concrete are:
1. Slump test: This test measures the consistency or
workability of fresh concrete. It involves filling a cone-shaped
mould with concrete and then lifting it up to see how much
the concrete slumps or subsides. The slump value indicates
how easy or difficult it is to place and compact the concrete.
A higher slump means more workable concrete, while a
lower slump means stiffer concrete. The slump test is usually
done on site before pouring the concrete.
2. Air content test: This test measures the amount of air
entrapped or entrained in fresh concrete. Air content affects
the strength, durability, and workability of concrete. Too
much air can reduce the strength and density of concrete,
while too little air can make the concrete susceptible to
freezing and thawing damage. The air content test is done
by using either a pressure meter or a volumetric meter.
3. Compressive strength test: This test measures the
ability of hardened concrete to resist compressive forces. It
involves crushing cylindrical concrete specimens in a
compression-testing machine. The compressive strength is
calculated from the failure load divided by the cross-
sectional area resisting the load.
The compressive strength test is the most important and
common test for concrete quality. It is used to determine the
grade and quality of concrete.
4. FLEXURAL TENSILE TEST:
This is another indirect method to determine the tensile
strength of concrete using a concrete beam that bends
under a transverse load. It involves placing a concrete beam
on two supports and applying a load at the mid-span or at
two symmetrical points. The load causes the beam to bend
and develop tensile stress at the bottom surface. The
flexural test is commonly used for concrete pavements and
slabs, but it gives an approximate value of the tensile
strength of concrete.
SUSTAINABLE MATERIALS OF CONCRETE:
Sustainable materials and practices of concrete are important for
reducing the environmental impact of concrete production and
construction. Some of the sustainable materials that can be used
in concrete are:
Supplementary cementitious materials (SCMs): such as
fly ash, slag cement, and silica fume, which can replace
some of the cement and reduce the carbon footprint of
concrete. It contributes to the property of hardened concrete
through hydraulic activity.
Recycled concrete aggregate (RCA): It is obtained from
crushing and processing old concrete, and can be used as a
substitute for natural aggregate in new concrete.
Manufactured sand (M-sand): It is produced from crushing
rocks or quarry waste, and can be used as a fine aggregate
in concrete instead of natural sand.
INNOVATIONS IN CONCRETE:
Innovations and material technology of concrete are important for
improving the performance, sustainability, and aesthetics of
concrete as a building material. Some of the innovations and
material technologies of concrete that are being developed or
used in the construction industry are:
Translucent concrete: It is created by adding optical fibers
to a concrete mix, allowing light to pass through the concrete
and creating a unique visual effect.
Carbon-neutral concrete: It is achieved by replacing some
of the cement with a low-carbon substitute made from
captured industrial emissions, a mineral that can absorb
CO2.
Biogenic limestone: It is produced by growing algae that
can convert CO2 into limestone and using it as a
cementitious material.
High-strength concrete: It can reduce the amount of
concrete needed for a given structure and save on material
and energy consumption.
IMPACT OF CONCRETE ON ENVIRONMENT:
Concrete also has some negative effects on the environment.
Some of the main environmental impacts of concrete are:
It contributes to global warming by emitting carbon dioxide
(CO2), a greenhouse gas, during its production and use.
The cement industry, which produces the main ingredient of
concrete, is responsible for about 8% of the global CO2
emissions.
Cement manufacturing involves heating limestone and other
raw materials to produce clinker, which releases CO2 as a
by-product2. Concrete also emits CO2 when it reacts with
water and air during curing and hardening.
It damages the soil by covering the fertile top layer and
reducing its quality and productivity.
TRAMSPORTATION OF CONCRETE:
Transportation of concrete is the process of moving fresh
concrete from the mixing plant to the construction site, where it
will be used for building structures. The main goal of
transportation of concrete is to maintain the quality and properties
of concrete, such as water-cement ratio, slump, air content, and
homogeneity1. There are different methods of transportation of
concrete, depending on the type and amount of concrete, the
distance and height of the site, the topography and weather
conditions, and the cost and speed of the process.
Some of the common methods of transportation of concrete are:
1. Mortar pans 2. Wheel barrows 3.Tower bucket
4. dump truck 5. Concrete pumps 6.transit mixers
SAFETY MATERIALS USE IN CONCRETE:
safety materials used in concrete are important to protect the
workers and the concrete itself from various hazards. Some of the
safety materials used in concrete work are:
Boots and gloves: Boots and gloves prevent the chemicals
in the cement used in concrete from causing skin irritation or
chemical burns. They can also protect your hands and feet
from nicks and abrasions caused by flying debris.
Eye protection: Eye protection such as goggles or safety
glasses can prevent dust, splashes, or flying particles from
entering the eyes and causing injury or infection.
Respiratory protection: Respiratory protection such as
masks or respirators can reduce the exposure to dust and
fumes from concrete, especially when cutting, grinding, or
drilling concrete.
Protective clothing: Protective clothing such as long
sleeves, pants, and hats can shield the skin from sunburn,
heat stress, and cold exposure.
Protective treatments: Protective treatments such as
sealers, coatings, or membranes can enhance the durability
and performance of concrete by preventing or reducing the
effects of substances that can attack and deteriorate it.
