Author: haroonkhan

An arbitrary division has been made for the setting time of cement as the initial setting time and final setting time. Vicat’s apparatus is used for setting times also. 1. Initial Setting Time About 500 g of the cement sample is taken and water content 0.85 P, where P is the percentage of water required as per the…

Consistency Test is conducted to find the setting times of cement, viz., initial setting time and final setting time. The test is conducted using a standard consistency test apparatus, viz., Vicat’s apparatus (Fig. 6.6). Figure 6.6 Vicat apparatus with various plungers Standard or normal consistency of cement paste is defined as that water content which will…

About 100 g of cement is weighed and sieved using a 90-micron IS sieve. Air-set lumps are broken and the cement is sieved continuously in a circular and vertical motion for a period of 15 minutes. A mechanical sieve shaker may also be used. The residue left on the sieve is weighed. This weight shall…

Fineness of cement is responsible for the rate of hydration and rate of evolution of heat and hence on the rate of gain of strength. Finer the grains, more is the surface area and faster the development of strength. The fineness of cement can be determined by the following tests:

The following tests are conducted on cement in the laboratory (IS: 4031 – PT 1 to 15, 1989):

At present, Ordinary Portland Cement is available in three different grades in India as 33-grade (IS: 269–1989), 43-Grade (IS: 8112–1989) and 53-grade (IS: 12269–1987). The numbers 33, 43 and 53 correspond to the 28-day compressive strength of cement-mortar as 33 MPa, 43 MPa and 53 MPa. The strengths are obtained from standard tests on cement–sand…

1. High Alumina Cement It is the cement obtained by grinding high alumina clinker. This has a long initial setting time, high ultimate strength, high resistance to the action of acids and high temperature. This cement is used for furnace insulation, refractory concrete and for special structures which require imperviousness and corrosion resistance. 2. Masonry…

Types of Portland Cement Code (IS: 456:2000) permits the use of the following Portland cement for a specific work: 1. Ordinary Portland Cement (OPC) Ordinary Portland Cement of grades 33, 43 and 53 are permitted. Only these cements are most commonly used in general concrete construction. 2. Rapid Hardening Portland Cement (RHPC) This cement conforms…

The main constituents in the manufacture of cement, as discussed earlier, are lime, silica, alumina and iron oxide (Table 6.1). These oxides interact with one another in the kiln at a high temperature, and more complex compounds are formed. The relative proportions of these oxides are fully responsible for the various properties of cement, rate…

In the dry process, the raw materials are crushed dry, and the correct proportion of the materials is fed into a grinding mill. In the grinding mill, they are dried and finely powdered. The dry powder is then blended and corrected for its right composition and then mixed again by means of compressed air. The…