Cement, Ingredients of cement, Physical properties of cement

What is cement??

Definition- Cement is product manufactured by burning and crushing to powder an intimate and well proportion mixture of calcareous and argillaceous material is called cement.

Cement as a binding material, is a very important building material in almost every construction work. The common types of cement are ordinary Portland cement (OPC) and simply Portland cement.

In India, Portland cement was manufactured in 1904 by South Industrial Limited at Madras, but it failed between 1912 and 1913, The Indian Cement Company was formed at Portbandar, and by 1918, three factories ware established. Now India holds the 2^nd place in the world in cement manufacturing.

Ingredients of cement

Lime (60-75%)

Silica (17-25%)

Alumina (3-8%)

Magnesia (1-3%)

Iron oxide (0.5-6%)

Calcium sulfate (0.1-0.5%)

Sulfur trioxide (1-3%)

Alkaline (0-1%)

Physical properties of cement

·         Fineness

·         Consistency

·         Setting time

·         Compressive strength

·         Soundness

Fineness:-  fineness of cement refers to size of grains or particles of cement, lesser than grain size, finer than cement. Due to small size of cement grains, greater surface are available to contact with water and reaction of hydration becomes faster, therefore cement grain its strength rapidly and rate of evolution of heat increases.  

Method for Fineness of cement (by IS codes)

Sieve test (IS 4031-1,1996)

Air permeability test (IS4031-2,1996)

Consistency:-  consistency of cement refers to thickness or thinness of cement paste when cement is mixed with water. for finding consistency of cement standard consistency

test (IS:4031-4,1988) is to be done.

Definition of standard consistency:- standard consistency is defined as that consistency which will permit the standard Vicat plunger to percentage a depth of 33 to 35 mm from the top of mount in standard Vicat apparatus.

Setting time:- there are two types of setting time

(a)    Initial setting time:-  (IS 4031-5,1998,2000)initial setting time is the time elapsed between moment when water is poured it in cement to moment when the cement paste starts losing its plasticity.

(b)    Final setting time:-  (IS 4031-5,1998,2000) final setting time is defined as the time elapsed between the moment when water is added to cement and the moment when the  paste completely lost its plasticity.

 

Compressive strength:-  compressive strength of cement is ability of cement specimen to resist the compressive stress. It is idea about characteristics of cement.  (IS 516:1959)

Soundness:-  (IS 4031-3,1998,2000) Soundness of cement can be defined as its ability to retain its volume after it gets hardened. The soundness test ensure that the cement dose not show excessive thermal expansion and if it dose, it can be rejected.