Cement is the binder that holds concrete and mortars together and hence it plays the most critical role in giving strength and durability to your home. It is used to make concrete for slabs, foundations, beams, columns, lintels, chhajja (sunshades), and mortar for brickwork, plastering, flooring and other such work.
Types of Cement used in house construction:
Cements used for domestic building such as your home are basically of three types:
- Ordinary Portland Cement (OPC): A combination of clinker and gypsum.
- Portland Slag Cement (PSC): A combination of good quality blast furnace slag (from the iron and steel industry) with clinker (which makes OPC) and gypsum.
- Portland Pozzolana Cement (PPC): A combination of fly-ash (from thermal power plants) with clinker and gypsum.
Ideal cement for house construction:
The best cement for house construction is blended cement like PSC and PPC. But please note that good quality blended cements like PSC and PPC will take more time to set. However the final strength after 28 days will be much more.
Features of good quality cement:
- Reduced water requirement.
- Improved workability .
- Less permeable to moisture.
- Improved resistance to acids and chlorides.
- Reduced heat of hydration.
- Easier to finish.
- Reduced shrinkage.
- Reduced leaching problems because it is low on free lime.
The colour of cement has no relation to the strength characteristics. There is a wrong impression that darker color cement gives better strength. In fact, darker color cement causes the workers to add more sand than allowed in cement-sand mortar for plastering, which can then cause problems.
Selecting the right cement for your house:
It is very important that you use only a reputed brand of cement. Good brands of cement may cost 2 to 5% more but offer quality, consistency and reliability as well as 10 to 20% greater strength characteristics. Cement accounts for a mere 12 to 18% of the total expenditure on your home. So, using cheaper cement gives you little overall savings but a greater risk to the strength of your building!
The right way of using cement in construction:
Cement must be added to the concrete and mortar in a precise, consistent manner. Too little or too much cement in concrete and improper water-cement ratios cause lower strengths, shorter design life and lower durability. Never try to save on cement use by diluting the concrete mix. Remember, that by using 30 to 40 bags less of cement, you would save no more than Rs 3000 to Rs 4000.