Mr Hau Yu, Dr Wei VictorLiu, Dr Yashar Pourrahimian, Mr Linping Wu
The mining industry frequently uses shotcrete as ground support. However, there is always a concern on its shrinkage-induced cracking. A possible solution is the use of expansive mixtures to mitigate cracking, but the effects of fibers—common in shotcrete—on expansive mixtures were not well known. To this end, the objective of this paper is to study the effects of various fibers on expansive shotcrete mixtures containing calcium sulfoaluminate cement. In this study, we investigated the influence of fibers based on the parameter changes, such as volume, density, permeable voids, water absorption, splitting tensile strength (STS), and unconfined compressive strength (UCS). We found that fibers decreased water absorption and reduced permeable pore space contents. Also, fibers restrained expansion of mixtures from 28% to 50% as per different types. Moreover, the addition of fibers improved the STS of mixtures from 38% to 57% and the UCS from 16% to 31%, respectively. In summary, these results indicate that fiber additions can control shotcrete expansion properly and improve its durability and mechanical strengths. Furthermore, this study provided preliminary findings on the development of new types of crack-mitigating shotcrete mixtures that contain both fibers and calcium sulfoaluminate cement.