In this paper, adiabatic temperature rise test was used to evaluate the effect of the type and content of accelerator on cement hydration in shotcrete. Two kinds of accelerators, alkaline and alkali-free accelerators were used in the experiments. For each type of accelerator, two different concrete mixture were used, and the dosage of the accelerator was 3% and 7% respectively. The experimental and theoretical results show that the use of alkaline or alkali-free accelerator can significantly improve the hydration rate in the first and second stage for shotcrete, but the alkaline accelerator will reduce the final hydration degree obviously, however the effect of alkali-free accelerator is small or even slightly increase. With the increase of the content of accelerator, the final hydration degree of concrete decreases, whether for alkali-free or alkaline accelerators. The mechanism may present in two aspects. For alkali-free accelerator, the hydration products are mainly rod-shaped AFt which will make concrete lose fluidity but do not completely cover the surface of the cement particles, and the acid substances in alkali-free accelerator will accelerate the dissolution of C₃S, thus promoting the hydration reaction. However, for the alkaline accelerator, the hydration products are mainly composed of C-A-H, AFm and a small amount of C–S–H gel which will wrap on the surface of cement particles, thus affect the further hydration of cement particles. The proposed cement hydration rate model can well predict the development process of the hydration degree for shotcrete, especially for the early age concrete.

本文采用绝热温升试验来评价促进剂的种类和含量对喷射混凝土水泥水化的影响。实验中使用了两种促进剂，即碱性和无碱促进剂。对于每种类型的促进剂，使用两种不同的混凝土混合物，促进剂的用量分别为3％和7％。实验和理论结果表明，使用碱性或无碱促进剂可以显着提高喷浆第一，第二阶段的水化速率，但碱性促进剂会明显降低最终水化度，但无碱的效果加速器很小甚至略有增加。随着促进剂含量的增加，混凝土的最终水化度降低，无论是无碱还是碱性促进剂。该机制可以表现为两个方面。对于无碱促进剂，水合产物主要是棒状AFt，这会使混凝土失去流动性，但不能完全覆盖水泥颗粒的表面，无碱促进剂中的酸性物质会加速C的溶解。₃ S，从而促进水合反应。但是，对于碱性促进剂，水合产物主要由CAH，AFm和少量包裹在水泥颗粒表面的C–S–H凝胶组成，从而影响水泥颗粒的进一步水化。所提出的水泥水化速率模型可以很好地预测喷射混凝土尤其是早期混凝土的水化程度的发展过程。