Cement

LAKSHMI NARAIN COLLEG OF TECHNILOGY

SESSION :2014-2015

A PRESENTATION ON :CONCRETE

SUBMITTED TO : SUBMITTED BY :ER. ANKIT SIR PRADHAN RISHI SHARMA PANKAJ MANDELA PRAGYA JAIN PRACHI SEN PREM GOUR

What is concrete ?

● Concrete is a composite material composed mainly of water, aggregate, and cement. Often, additives and reinforcements (such as rebar) are included in the mixture to achieve the desired physical properties of the finished material

Uses of concrete

● Concrete is widely used for making architectural structures, foundations, brick/block walls, pavements, bridges/overpasses, highways, runways, parking structures, dams, pools/reservoirs, pipes, footings for gates, fences and poles and even boats

● Concrete is used in large quantities almost everywhere society has a need for infrastructure.

Concrete is used in large quantities almost everywhere mankind has a need for infrastructure.

Raw material of concrete

Composition of concrete

Types of concrete

● Normal concrete● High Strength Concrete● High Performance Concrete● Light Weight Concrete● Self Compacting Concrete

Normal concrete

● The concrete in which common ingredients i.e. aggregate, water, cement are used is known as normal concrete.

● It has a setting time of 30 - 90 minutes depending upon moisture in atmosphere, fineness of cement etc.

● The development of the strength starts after 7 days the common strength values is 10 MPa (1450 psi) to 40 MPa (5800 psi). At about 28 days 75 - 80% of the total strength is attained.

● Almost at 90 days 95% of the strength is achieved.

High strength concrete

● Compressive strength of high strength concrete mix is usually greater than 6,000 pounds per square inch.

● High strength concrete is made by lowering the water cement (W/C) ratio to 0.35 or lower.

● Often silica fume is added to prevent the formation of free calcium hydroxide crystals in the cement, which might reduce the strength at the cement aggregate bond.

● Low w/c ratios and the use of silica fume make concrete mixes significantly less workable, which is particularly likely to be a problem in high-strength concrete applications where dense rebar cages are likely to be used.

● Aggregate must be selected carefully for high strength mixes

Application of HSC

Light weight concrete

● The concrete which has substantially lower mass per unit volume then the concrete made of ordinary ingredients is called lightweight concrete. The aggregates used are lighter in weight.

● Density of light weight concrete is 240 kg/m³ (15pcf) -1850 kg/m³ (115 pcf).

● Strength of light weight concrete blocks varies from 7 MPa (1000 psi) - 40 MPa (5800 psi).

● Some times Air Entrained Admixtures are also added to it giving resistance to freezing and thawing along with strength.

Application of LWC

Self compacting concrete

● The concrete where no vibration is required. The concrete is compacted due to its own weight

● It is also called self consolidated concrete or flowing concrete

● It can be also categorized as high performance concrete as the ingredients are the same, but in this type of concrete workability is increased

Application of SCC

Thank You All !!