Physical properties of 53 grade cement as per IS 12269
Portland cements are commonly characterized by their physical properties for quality control purposes. Their physical properties can be used to classify and compare Portland cements. The challenge in physical property characterization is to develop physical tests that can satisfactorily characterize key parameters. IS 12269 describes the physical requirements of ordinary portland cement 53 grade as per following
Process of hydration and resulting the rate of strength gain is affected by fineness of cement. Finer cement offers more surface area for hydration thus rapid strength gain occurs during first seven days.Fineness is measured by Blaine’s air permeability method as describe in IS 4301. The specific surface 01 cement shall not be less than 225 m2/kg.
Soundness is define as the ability of a hardened cement paste to retain its volume after setting without delayed expansion. This expansion is caused by excessive amounts of free lime (CaO) or magnesia (MgO). Most Portland cement specifications limit agnesia content and expansion.Soundness test is done by by the ‘Le Chatelier’ method OR autoclave test described in IS : 4031. Expansion should not be more than 10 mm and 0.8 percent respectively for unaerated cement.
Many factors affects setting time of cement such as fineness of cement, chemical content,admixtures etc. Setting time of cement test is done by Vicat Apparatus. Usually two setting times are define i.e. Initial setting time and Final setting time. For construction purposes, the initial set must not be too soon and the final set must not be too late. 53 grade ordinary portland cement shall confirm to following
a) Initial setting time shall not be less than 30 minutes
b) Final setting time shall not be greater than 600 minutes.
The average compressive strength of at least three mortar cubes ( area of face 50 cm2 ) composed of one part of cement, three parts of standard sand (conforming to IS : 650) by mass and P/4+ 3 % ( of combined mass of cement plus sand ) water, and prepared, stored and tested in the manner described in IS : 4031, shall be as follows:
- 72 +/- 1 hr, not less than 2.7 KN/cm2
- 168 +/- 2 hrs, not less than 3.7 KN/cm2
- 672 +/- 4 hrs, not less than 5.3 KN/cm2