Experimental Study on Self Curing Concrete Using Natural and Recycled Coarse Aggregate

Abstract

A self-curing concrete is provided to absorb water from atmosphere to achieve better hydration of cement in concrete which solves the problem of lowered cement hydration because of improper curing and thus unsatisfactory properties of concrete.

The present investigation involves the use of self-curing agent viz., polyethylene glycol (PEG) of molecular weight 6000 (PEG 6000) for dosages ranging between 0.5 to 2% by weight of cement added to mixing water. The experimental program was planned as the following. Total 120 cubes, 120 cylinders, 120 prisms were cast which involves different dosages (0%, 0.5%, 1% and 2%) of self-curing agent PEG-6000 for four different mixes (Mix 30 and Mix 40), under different curing conditions (indoor, conventional) with different aggregates (normal coarse aggregate and recycled coarse aggregate).Comparative studies were carried out for self curing of recycled coarse aggregate and self curing of normal coarse aggregate. Comparative studies were carried out for water retentivity, compressive strength, split tensile strength, flexural strength for 7 days and 28 days for conventional cured and self cured concrete. The properties of self-cured concrete are at least comparable and some time better than those of concrete with traditional curing. The comparative studies for strength were carried out at different dosages for different coarse aggregate. The results indicate that selfcuring concrete has shown greater strength compared to conventional curing concrete. The maximum strength for normal coarse aggregate concrete is at dosage of 2% SCA and for recycled coarse aggregate concrete is at dosage of 1% SCA and then decreases. For concrete using normal coarse aggregate in place of Recycled coarse aggregate the compressive strength was found to be 7.5% more at 28 days. The compressive strength of self curing concrete is 3% more then that of the concrete with conventional curing curing 28 days.

Similarly the spilt tensile strength with normal coarse aggregate was found to be 7% more then with recycled coarse aggregate at same 28 days testing. Again the split tensile strength was found to be 3.1% more then the concrete with conventional curing at 28 days testing. The flexural strength 5% is more for natural coarse aggregate concrete compared to recycled coarse aggregate concrete 28 days. The flexural strength 2% more for selfcuring concrete compared to the conventional curing concrete for 28 days. The maximum weight loss in the concrete occurs at 0% of SCA and increases with increases in percentage of SCA.