Combination Effects of Internal Curing and Permanent Formwork on Shrinkage of High Strength Concrete

Abstract

In this paper, the influences of internal curing using pre-soaked lightweight aggregate (PSLWA) and pre-fabricated fiber reinforced engineered cementitious composite (ECC) board as permanent formwork on shrinkage and internal relative humidity of high strength concrete were investigated. Three mixture proportions with induced curing water-to-cement ratios (W IC /C) of 0, 0.08 and 0.12 were utilized in the experiments. The test results show that the progress of the internal relative humidity of high strength concrete since casting exhibits first a vapor saturated stage (RH=100%, stage I), followed by a gradually reducing stage (RH<100%, stage II). As PSLWA is added, the reduction rate of internal relative humidity in stage II is greatly decreased. As ECC cover is used, the reduction on internal humidity of high strength concrete is further reduced. Shrinkage of high strength concrete decreases with increase of induced internal curing water. However, internal curing cannot completely eliminate the shrinkage of high strength concrete developed in the stage I. The combined effects of internal curing and ECC cover can reduce the shrinkage not only developed in the stage II, but also the shrinkage developed in stage I.

Influence of Curing Conditions on Properties of Normal and High Strength Concrete with and without Pre-Wetted Lightweight Aggregates

“…In these methods, the use of pre-wetted lightweight aggregates (LWAs) can provide additional water for curing and largely restrain the self-shrinkage of concrete (Bentur et al 2001;Bentz 2009;Paul and Lopez 2011;Wei et al 2014;Zhang et al 2014Zhang et al , 2016, which is called internal curing method and firstly proposed by Philleo (1991). Moreover, the water content in LWA, particle size and pore structure of LWAs determine its curing effect as internal curing agents in concrete (Bentz and Weiss 2011).…”