A study of the effect of rheological properties of fresh concrete on shotcrete-rebound based on different additive components

Abstract

In order to reveal the laws surrounding the rheological properties of fresh concrete on shotcrete-rebound characteristics, this paper aims to study the relationship between the rebound rate of wet-mix shotcrete and the rheological properties of fresh concrete slump, yield stress, plastic viscosity, etc), as well as the relationship between shotcrete-rebound and energy loss by adding additive components of different types and dosages. The additional components involved in this paper include polypropylene fibre, a polycarboxylic water reducing agent, an alkali-free accelerator, and an organic polymer tackifier. The experimental results show that the shotcrete-rebound materials are distributed in a fan shape, and the coarse aggregate in the rebound materials accounts for the largest proportion. If the amount of accelerator (3%–7%) and tackifier (1%–3%) increases, the rebound rate of the wet-mix shotcrete decreases. Also, if the amount of water reducing agent (0.5%–1.5%) increases, the rebound rate of the wet-mix shotcrete increases. Finally, if the fibre content (0.6 kg/m3–1.8 kg/m3) increases, the rebound rate of wet-mix shotcrete first decreases and then increases. Through the analysis of correlation and multiple linear regression, it has been concluded that changes in the slump, yield stress, and bleeding rate significantly affect the concrete rebound rate, and a multiple linear regression equation for predicting the rebound has been obtained. The energy loss of the shotcrete is proportional to the shotcrete rebound rate, and can also be used as an evaluation index of shotcrete performance.