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Properties of Cements

Cement

Cement is a binder, that can sets and hardens independently and is used to bind some other materials together. The volcanic ash and crushed pulverized brick additives are altogether added to burnt lime to lime to obtain a hydraulic binder were later called as cementum, cimentum, cament and cement.

Cement which is used in construction is characterized as hydraulic and non hydraulic. Example for hydraulic cement is Portland cement, and example for Non hydraulic cement is Lime and gypsum plaster. The most important use of cement is the production of mortar and concrete. Concrete should not be confused with cement, concrete is the combination of cement and aggregate.

Physical properties of cement

The mentioned physical properties of cement are about; setting time, strength, soundness, fineness of grinding. For determining these properties, IS 268-1975 prescribes the requirement and the standard procedure.

Table: Requirement Physical properties of cement

Physical property	Standard prescribed
(a)Setting time Initial Final	For initial not less than 30 min For final not more than 600 min
(b)Compressive strength of mortar with standard sand After 3 days ± 1hour After 6 days ± 2 hour Tensile strength After 3 days After 7 days	Not less than 16 N/mm² Not less than 22 N/mm² Not less than 2.0 N/mm² Not less than 2.5 N/mm²
(c)Soundness By Le-Chatelier method By autoclave method	Expansion should not be more than 10mm Expansion should not be more than 0.5%
(d)Fineness Residue by weight on IS 90 micron sieve Specific surface by air permeability method	Not more than 10% Not less than 2250.

Properties of Cement Mortar

The following are properties of cement mortar,

When water is added to initiate dry mixtures of cement and sand, hydration of cement starts and it will binds sand particles as well as the surrounding surfaces of masonry and concrete.
The proportion of cement and sand will decide the strength of mortar.
A richer mix than 1:3 proportion is prone to shrinkage.
Solid surface are provided by well proportioned mortar.
A leaner mix is not able of closing the voids in sand.

Properties of cement concrete

Properties of cement concrete are, concrete has high compressive strength but lower tensile strength and it is usually reinforced with materials that are strong in tension. At lower stress level, the elasticity of concrete is constant, but it starts decreasing at higher stress levels as matrix cracking develops. Every concrete structure will crack to some extent, because of its shrinkage and tension.

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