Effect of blended concrete and intermittent curing sequences on rigid pavement

Abstract

Concrete is a carefully controlled mixture of cement, fine aggregate, coarse aggregate and water. It starts gaining strength from the instant of time since water is added to the dry mass of the ingredients. Concrete thus prepared at t (time)=0 hour but placed into the mould at a time lag t is bound to be, adversely affected in strength, (henceforth it is used to denote, compressive strength, tensile strength, bond strength, shear strength, elastic modulus, modulus of rupture. Concrete thus achieved by laying a  "fresh" concrete mass over relatively "older" preset mass of concrete ( be of the same or of different mix types) at a certain delayed time of casting is often observed at construction work may be termed as layered concretes or "Spread Concretes". Selfing and Crossing of concrete provides a wide scope in preventing the wastage of concrete materials which is partially set, which is not suitable for good quality of construction. After applying selfing technique to such partially set concrete at different delayed times , it is seen  that there is an increase  in strength as compared to old concrete mixes which is most of the time acceptable. It is seen that the strength of concrete prepared at t = 15 minutes is less as compared to the same concrete at t = 15 minutes selfed with a fresh concrete of same grade. Curing method applied with four sequences Air₀ Water₂₈, Air₂₈ Water₀, Air₇ Water₂₁, and Air₂₁ Water₇.  It is observed that the strength of concrete which undergoes intermittent curing is less than that of strength due to cumulative curing after 28 days of curing