Internal curing on high performance concrete with pre-soaked light weight aggregate to prevent shrinkage

Abstract

Concrete with low water-cement ratio has been encouraged in construction because of the improvement in strength and durability. However, higher shrinkage leads to early age cracking in the structures even though there is an increase in strength and reduction in permeability. The cracks due to shrinkage can be reduced by using internal curing agent. This can be achieved with the supply of required volume of water by using light weight aggregate as internal curing agent which nullifies the crack effect due to shrinkage. In the study a mix ratio of 1:1.76:2.52:0.36 was used to cast cubes, prisms and beams to investigate the strength properties of high performance concrete using silica fume and super plasticizer. The high performance concrete specimens were cast by replacement of cement with 12% of silica fume and addition of 6%, 12%, 20% light weight aggregate like vermiculite and saw dust. From the compression test result, optimum replacement percentage of light weight aggregate was found out and used for casting prisms and beams. The results of flexural tests conducted on beam specimens indicates that 6% replacement of saw dust gives higher strength in both water and internal curing conditions. Replacement of vermiculite (6%) as a Lightweight material reduced shrinkage significantly and prolonged the net-time to cracking considerably.