Question

Briefly discuss how does the incorporation of aggregates influence strength of cement basis materials (hint explain why strength of concrete is lower than strength of cement paste)

Answer 1

Cement paste means the mixture of cement ( portland or puzzolona cement) and water, it is just a filler material, strength is weak, used in binding purpose to fill the joint, where concrete, which is the bearing material, has high steength, is the mixture of cement paste and aggregates i.e coarse and fine aggregates. Aggregates in the concrete bears 75 to 80 percent of the weight of concrete, accounts concrete's thermal and elastic properies with its dimensional stability. Fresh concrete is more workable with shape and texture than the hardened concrete. Round or smooth surface of aggregate gives more workable concrete, where rough surfaced aggregate gives more strength of concrete. To maintain proper water to cement ratio (w/c ratio) the aggregate maybe in Saturated surface dry (SSD) or Oven dried (OD) condition.

So, from these we can say aggregate is the inert filler in the concrete, but different types of aggregate gives different types of strength, workability in concrete.