Raft foundations (sometimes known as Mat Foundations) are a large concrete slab reinforced with steel which can support a number of columns and walls. The slab is spread out under the entire building or at least a large part of it which lowers the contact pressure compared to the traditionally used strip or trench footings. This is basically a material that holds the wet reinforced concrete of the raft foundation in place until it cures. This material is mostly of wood, but this idea of formwork become obsolete internationally and it is gradually becoming obsolete in the country with the introduction of our steel shutters, steel panel or steel formwork.

STEEL SHUTTERS (ADVANTAGES)

1) ITS CHEAPER

It is cost effective and economical. The average cost of formwork using wood for a raft foundation is about five hundred thousand naira (500,000.00) while with steel shutters it’s a about half the cost of wood for an average building.

2) BETTER QUALITY END PRODUCT

The finished work when steel shutters are used gives perfect quality with no honey combs on the surface of raft foundation unlike wood that will bulge with lots of honey combs.

3) IT ELIMINATES WASTE

Steel shutters are reusable as justified by the fact that it is made of steel, therefore it can be use subsequently as against wood that is condemned after use due to water and weather.

4) IT MAINTAINS A CLEAN ENVIRONMENT

Steel shutters when dismantled after use is easily removed from site with no extra cost, unlike wood that litters around site thereby making the entire surroundings unkempt. On other hand, cold-formed thin-walled profiled steel decking sheets with embossments on top flanges and webs are widely used in many composite slab constructions. Profiled steel deck performs two major functions that act as a permanent formwork during the concrete casting and also as tensile reinforcement after the concrete has hardened. The only additional nominal light mesh reinforcement bars that need to be provided is to take care of shrinkage and temperature, usually in the form of welded wire fabric.