Chemical analysis of cement involves testing the material for all the chemical requirements stated in the relevant international standard, which would normally involve such tests as general chemical composition. Conducting the suite of testing ensures that cement supplied does indeed meet the standard required.
This test is used to determine whether cement meets the compressive strength requirements of international standards. The test consists of casting a number of standard cubic specimens in laboratory conditions, using standard sands and then testing them for compressive strength after the required curing period has elapsed, normally 28 days.
The fineness of cement has a significant effect in its physical properties when used in concrete. Generally the finer the cement powder, the more rapid the concrete will set, as there is an increase in its surface area.
The measure of fineness is usually undertaken by sieving, and the result assessed against the cement standard for compliance.
The chemical reaction that takes place between cement when mixed with water is exothermic. The intensity of this reaction is measured in this test. The value of heat of hydration can be important where the cement maybe incorporated into concrete, which will be poured in large volumes. In such cases there can be a considerable built up of heat as the reaction takes place, which, if excessive, could caused cracking in the structure..
This test is used to determine the percentage loss of material in a cement specimen when subjected to high temperature. It is used as a measure of deleterious material in the cement, the level of which is normally controlled in cement manufacturing standards.
Physical analysis of cement involves testing the material for all the physical requirements stated in the relevant international standard, which would normally involve such tests as compressive strength and fineness amongst others. Conducting the suite of testing ensures that cement supplied does indeed meet the standard required.
The time it takes for a cement to stiffen to a standard value after addition of water is commonly known as the set time. The test involves mixing cement with water and then measuring its resistance to penetration of a standard probe at varying intervals of time, until a certain value is reached..
The main purpose of the soundness test is to assess the possible risk of late expansion due to hydration of uncombined calcium oxide and/or magnesium oxide. The test uses apparatus known as Le Chatelier apparatus, which magnifies any expansion during heating to a value that can be measured.