Role of chemical admixtures in improving wet-mix shotcrete performance for ground support

摘要

This paper presents the results of laboratory and field experiments conducted for a major ground support operation to assess the performance of wet-mix shotcrete incorporating various chemical admixtures. The project had an alkali-silica reaction (ASR) risk due to the aggregates available in the region being reactive. Therefore, a customised mix design was prepared and specialty chemical admixtures formulated with the latest available technologies were selected to mitigate the ASR while meeting the project specifications. The performance of the proposed system, which contained 25% fly ash and 0.8% of pozzolanic-based rheology control agent, was compared with the reference mix containing 8% silica fume as well as the target performance limits of the project. Test results showed that, when compared to the reference mix, the proposed system improved the shotcrete performance by reducing the ASR potential, increasing early-age strength, enhancing sprayability by increasing the stickiness and cohesiveness, and meeting later-age strength, toughness, and durability requirements.