Cement Testing

we need to determine the fineness of cement by dry sieving as per IS: 4031 (Part 1) – 1996.The principle of this is that we determine the proportion of cement whose grain size is larger then specified mesh size.

The apparatus used are 90m IS Sieve, Balance capable of weighing 10g to the nearest 10mg, A nylon or pure bristle brush, preferably with 25 to 40mm, bristle, for cleaning the sieve.

The Specific gravity defined as the ratio between the weight of given volume of the cement and weight of an equal volume of water. The most popular method of determine S.G of cement is by use of the kerosene which doesn’t react with cement.

The setting and hardening of a cement is a continuous process, but two points are distinguished for test purposes. The initial setting time is the interval between the mixing of the cement with water and the time when the mix has lost plasticity, stiffening to a certain degree. It marks roughly the end of the period when the wet mix can be molded into shape.

The final setting time is the point at which the set cement has acquired a sufficient firmness to resist a certain defined pressure. Most specifications require an initial minimum setting time at ordinary temperatures of about 45 minutes and a final setting time no more than 10 to 12 hours.

It is the property of cement due to which it undergoes large change in volume after setting. This change in volume may cause crack and disintegration of concrete. To check the soundness of cement Le-Chatlier’s apparatus is used.

Compressive strength of cement indicates the compressive strength of cement mortar cubes (7.07cmx7.07cmx7.07cm) of 1:3 proportion, using standard sand as specified by IS :650 (1966) as fine aggregate, tested under compression (Grade of cement indicates their compressive strength at the end of 28 days of curing).

Many other properties of mortar / concrete are related to compressive strength of cement, because cement is used in structure in the form of mortar or concrete.

Concept Structure: