Chemical curing effects on in loco structural concrete strength evolution

Abstract

The compressive strength evolution of concrete is water availability and temperature dependent on its surroundings. Water restriction reduces the hydration rate of Portland cement and, consequently, the compressive strength. The increase in temperature enhances hydration and compressive strength at early ages. Opposite behavior can be observed at more advanced ages. In the present study, class C30 machined structural concrete, used in a predominantly residential construction development, was subjected to different curing conditions to analyze the effects on compressive strength at 3, 7, and 28 days. The reference curing procedure followed regulatory guidelines (NBR 5738). In the laboratory, the concrete was cured in air and sealed condition's using PVC film. At the site (on site), the concrete was chemically cured with the paraffinic hydrocarbon emulsion. Alternative curing procedures reduced the compressive strength of the concrete at all ages analyzed, with a variation between 7 and 30%. Chemical curing was the one that resulted in a great reduction in the concrete's compressive strength, despite the evolution of mass loss due to drying being similar to that of air curing.

Keywords
Chemical curing; In loco concrete; Compressive strength; Mass variation