Effect of Shrinkage Reducing Admixture on Drying Shrinkage of Concrete with Different w/c Ratios.

Mahdi Kioumarsi,Mohammad Haji,Fazel Azarhomayun,Mohammad Shekarchi

doi:10.3390/ma13245721

Abstract

The reduction of the moisture content of concrete during the drying process reduces the concrete’s volume and causes it to shrink. In general, concrete shrinkage is a phenomenon that causes concrete volume to dwindle and can lead to durability problems. There are different types of this phenomenon, among them chemical shrinkage, autogenous shrinkage, drying shrinkage including free shrinkage and restrained shrinkage, and thermal contraction. Shrinkage-reducing admixtures are commercially available in different forms. The present study investigates the effect of liquid propylene glycol ether on mechanical properties and free shrinkage induced by drying at different water-cement (w/c) ratios. Furthermore, the effect of shrinkage-reducing admixtures on the properties of hardened concrete such as compressive and tensile strength, electrical resistivity, modulus of elasticity, free drying shrinkage, water absorption, and depth of water penetration was investigated. The results indicated that shrinkage reducing agents performed better in a low w/c ratio and resulted in up to 50% shrinkage reduction, which was due to the surface reduction of capillary pores. The prediction of free shrinkage due to drying was also performed using an artificial neural network.

Highlights

Concrete is the most widely used building material in the world, such that in some countries, the use of reinforced concrete is more common than steel structures [1,2,3]
The aim of this study is to investigate the effect of shrinkage reducing admixtures (SRA) on the drying-induced shrinkage of concrete in different w/c ratios
C231 standards in order to determine the effect of different percentages of SRA on the workability and air content of the manufactured concretes

Summary

Introduction

Concrete is the most widely used building material in the world, such that in some countries, the use of reinforced concrete is more common than steel structures [1,2,3]. Drying shrinkage is more likely to occur in structures with a high surface-to-volume ratio. It has long been the concern of researchers in the field of concrete technology to find ways to reduce this type of shrinkage [4]. In this regard, one of the most effective methods is to use shrinkage reducing admixtures (SRA). Mora et al [4] showed that SRA, even in high strength concrete (HSC), reduces shrinkage and cracking due to a reduction in evaporation rate, and results in Materials 2020, 13, 5721; doi:10.3390/ma13245721 www.mdpi.com/journal/materials

Objectives

Results

Conclusion