Effect of steam curing cycles on strength and durability of SCC: A case study in precast concrete

Use of Self-Compacting Concrete (SCC) in pre-cast concrete plants is growing rapidly due to its benefits such as reduction in labor and equipment costs, increasing productivity, providing flexibility in filling highly reinforced sections and complex formworks, lowering the noise on job site and having superior surface quality. Also, considering the critical importance of "production time" in precast plants, accelerated curing is considered as an inevitable part of precast concrete elements production. In this study the effects of thirty-six different steam-curing regimes on the compressive strength and permeability of a self-compacting concrete mixture, used in precast concrete elements of Sadr elevated highway was investigated. Compressive strength measurements indicated that in a constant total time, increase in precuring period leads to lower immediate compressive strength. On the other hand, increase in treatment temperature and total cycle time (which means higher energy and time consumption) led to higher immediate compressive strength. Furthermore, durability tests results demonstrated that application of cycles with maximum temperature of 70 degrees C imposes negative effect on durability properties of reference SCC, such as surface resistivity and capillary absorption. Finally, on the basis of three criteria (compressive strength, permeability and energy consumption by steam curing cycle), an optimum steam curing cycle was introduced and utilized in the precast concrete plant. (C) 2013 Elsevier Ltd. All rights reserved.