Major ingredients of concrete are:
1. Binding material (like cement, lime, polymer)
2. Fine aggregate (sand)
3. Coarse aggregates (crushed stone, jelly)
A small quantity of admixtures like air entraining agents, water proofing agents, workability agents etc. may also be added to impart special properties to the plain concrete mixture.
Depending upon the proportion of ingredient, strength of concrete varies. It is possible to determine the proportion of the ingredients for a particular strength by mix design procedure. In the absence of mix design the ingredients are proportioned as 1:1:2, 1:11/2:3, 1:2:4, 1:3:6 and 1:4:8, which is the ratio of weights of cement to sand to coarse aggregate.
In proportioning of concrete it is kept in mind that voids in coarse aggregates are filled with sand and the voids in sand are filled with cement paste. Proportion of ingredients usually adopted for various works are shown in Table 3.1.
—–3.1 Plain Concrete
—————Functions of Various Ingredients
—————Preparing and Placing of Concrete
—————Curing of Concrete
—————Properties of Concrete
—————Properties of Green Concrete
—————Properties of Hardened Concrete
—————Tests on Concrete
—————Desirable Properties of Concrete
—————Uses of Concrete