Performance evaluation of mechanical properties of self-compacting concrete prepared with different cements types submitted to steam curing

Resumen

The steam curing is one of the mechanisms used in the precast industry to accelerate the strength gain of structural elements. The values of temperature and time of ideal cures to happen this strength gain vary with cement and mix design used in concrete. Little is known about the behavior of self-compacting concrete (SCC) when subjected to process of steam accelerated curing, especially in relation to its mechanical properties. This article evaluates the compressive strength of two mixtures design of self-compacting concrete class 40 MPa with two different cements, cement CP III 40-RS and CP II E-32 submitted normal curing (according to NBR 5738:2003 [2]), and steam curing. It used two different steam cured at 65°C and 80°C and three curing cycles, 4 h, 6 h and 8 h. The study was done at the Laboratory of Civil Engineering CESP - LCEC – Ilha Solteira/SP, where were tested concretes with specimens cylinder of 10 cm x 20 cm. The compressive strengths were obtained at the end of the steam curing plateau (called immediate strength to the cycle) and at ages 3, 7, 28, 56 and 91 days (called strength at advanced ages) and for concrete subjected to normal curing, the ages of rupture were performed with 3, 7, 28, 56 and 91 days. An analysis was made of correlation between the values of rupture of concrete subjected to normal cure with values of immediate strength to the cycle and also to the strength at advanced ages. The benchmarks were performed according to the type of cement used, curing temperature and time on the steam curing plateau. The results show that overall, the concrete with cement CP II E-32 showed a 65 º C, to the steam curing plateau for 4 hours the best value of compressive strength when subjected to these conditions of cure, while the concrete with cement CP III 40-RS presented to 65 ° C for 6 hours of steam curing plateau optimum value of strength.