Cement and Cement Concrete
Cement and Cement Concrete
Cement and Cement Concrete
CONCRETE
Prepared by
Biswajit Jena
M.Tech (Structural Engg.)
NIT Rourkela
CEMENT
Cement is the costliest and most
important ingredient of concrete.
Cement has cohesive and adhesive
properties which make him capable of
bonding the materials.
The cements of interest in the making of
concrete have the property of setting
and hardening under water by virtue of
chemical reaction with it are, therefore
called Hydraulic Cement.
Hydraulic cements consist of mainly of
silicate, sand aluminates of lime and can
be classified broadly as natural
cements. For e.g. Portland cement,
high alumina cement, etc.
CHEMICAL COMPOSITION OF CEMENT
Tetracalcium : 9±4%
Aluminoferrite (C₄AF) : 12±3%
Free Lime :
1±.5%
Different Types Of CEMENT
Ordinary Portland cement
(i) Ordinary Portland cement 33 Grade- IS 269:1989
(ii) Ordinary Portland Cement 43 Grade- IS 8112:1989
(iii) Ordinary Portland Cement 53 Grade- IS 12269:1987
Rapid Hardening Cement - IS 8041:1990
Sulphate Resisting Cement –IS 12330:1998
Quick setting Cement
Low Heat Cement –IS 12600:1989
Portland Pozzolana Cement – IS 1489 (Part-1) 1991 (Fly ash based)
Air Entraining Cement
Colored Cement - (White Cement IS 8042:1989)
Expansive Cement
High Alumina Cement- IS 6452:1989
CONCRETE
Concrete is a composite material composed of
gravels or crushed stones (coarse aggregate),
sand (fine aggregate) and hydrated cement
(binder),and imparts considerable hardness to
the mixture.
The cement reacts chemically with the water and
other ingredients to form a hard matrix which
binds all the materials together into a durable
stone-like material that has many uses.
Sometimes, additives such as pozzolans or super
plasticizers are included in the mixture
Most concrete is poured with reinforcing
materials (such as rebar) embedded to provide
tensile strength, yielding reinforced concrete.
Properties Of Concrete
Compressive strength
Tensile strength
Elastic Deformation
Shrinkage
Compressive Strength
Compressive strength is defined as the measured maximum
resistance of a concrete or mortar specimen to an axial load, usually
expressed in PSI(pound per square inch) at an age of 28days.
Concrete compressive strength depends upon many factors:-
-Quality & Proportions of the ingredients
-The curing environment
The grades are designated by one letter M (for mix) and a number
from 10 to 80 indicating the characteristic compressive strength (fck)
in N/mm2.
As per IS 456 (Table 2), concrete has three groups as (i) ordinary
concrete (M 10 to M 20), (ii) standard concrete (M 25 to M 55) and (iii)
high strength concrete (M 60 to M 80).
Note: The following grade of concrete are generally used in highway
pavements and are M30 M35 M40 M45.
Tensile Strength
Concrete is not normally resist to direct tension, the knowledge of
tensile strength is use to estimate to load under which cracking will
develop.
This is due to its influence on the formation of cracks and its
propagation to the tension side of reinforced concrete flexural
member.
The tensile strength of concrete is relatively low.
The flexural and splitting tensile strengths are obtained as described in
IS 516 and IS 5816, respectively.
However, the following expression gives an estimation of flexural
strength (fcr) of concrete from its characteristic compressive strength.