Slabs are the most common usage of concrete and come in 2 variants – waffle slabs and conventional slabs. Conventional slabs are those which have a deep excavated dug that penetrates into the ground. Waffle slabs are placed around ground level and consist of a stretched foam pad made of polystyrene.
Slabs require concrete which has a strength varying from 20-25mpa. However, it depends on the soil test and instructions given by the engineer.