Study on Development of M20 and M25 Grades of Self Curing Concrete Using Formaldehyde and Sodium Polyacrylate

Abstract

Abstract: Self-curing concrete, a specialized solution, eliminates external curing for optimal performance in construction. It maintains internal moisture, reducing autogenous shrinkage and early-stage cracking. This innovative approach, promoting sustainable practices, is valuable for high-rise buildings and bridges. Self-Curing properties achieved in concrete through the incorporation of Sodium Polyacrylate and Formaldehyde. Extensive testing was conducted on diverse concrete samples to evaluate their properties, encompassing workability, compressive strength, tensile strength, and flexural strength. Sodium polyacrylate which is a super absorbent polymer is added to the concrete mix of M20 & M25 grade of concrete in variations (0%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%) by weight of cement. Formaldehyde added to concrete mix used as shrinkage reducing agent is added 1% with water. Light weight aggregate like brick chips replaced 10% of coarse aggregate are used because bricks absorb and holds a large amount so water. So pre-saturated brick chips are also used to provide internal curing. Sand is replaced by wood powder by 5%, as it also absorbs water. The compressive strength tests were carried out on M20 and M25 grade concretes with different water-cement ratios (for M20 w/c ratio is 0.50 & for M25 w/c ratio is 0.40), adhering to BIS: 516 – 1959 standards. The results indicated that the addition of sodium polyacrylate by weight of cement up to 0.6% led to optimal compressive strength values, beyond which further additions resulted in a decline in strength. Similarly, the split tensile strength tests for M20 and M25 grade concretes showcased the highest values at 0.6% addition of sodium polyacrylate by weight of cement. Subsequent increases in the additive led to a decrease in split tensile strength. Finally, the flexural strength tests for both M20 and M25 grade concretes yielded their highest values at 0.6% sodium polyacrylate by weight of cement, with diminishing flexural strength observed with higher additive percentages. These findings offer valuable insights into enhancing the self-curing properties of concrete and optimizing its characteristics by utilizing sodium polyacrylate as an additive.