Effects of double expansion agents on the properties of interlayer in roller-compacted concrete

Abstract

Roller-compacted concrete (RCC) is widely used in the construction of large-scale infrastructure projects. The interlayer is the weakest plane of the entire RCC structure, and it readily deteriorates under the pressure of water and other environmental factors. In this study, cement mortar was used as the interlayer treatment material of RCC and supplementary cementitious materials (SCMs), including fly ash and silica fume, in which double expansive resources (HME, containing CSA and CaO) admixtures were added to modify the mortar properties. The results showed that HME significantly improved the ductility and toughness of the interlayer treatment materials for a curing time of 7 d. All three of fly ash-, silica fume- and HME-added samples showed improvements in relative permeability coefficient, shear strength, cohesive strength, and friction coefficient of RCC. In addition, the best performance was shown by 6 and 8 wt% HME-added samples. However, the 10 wt% HME-added samples showed performance degradation. Those results confirmed that a suitable deformation of the interlayer treatment materials was needed to improve the performance of the whole RCC structure. Thus, the use of interlayer treatment materials provides a new method for solving the problems of permeation and bond quality in RCC dam structures.