Effects of binder on suction in cemented gangue backfill

Cemented gangue backfill (CGB, a mixture of coal gangue, cement and water) is widely used in China for backfilling in coal mines. The addition of fly ash to CGB mixtures can help them to have favourable environmental and economic performance. In addition, mechanical stability and durability are also important performance criteria for CGB, and these two criteria are closely related to the suction of CGB. The evolution of suction in CGB is influenced by binder hydration, which is an exothermic process affecting the variation in temperature of CGB. To examine the coupled effects of binder hydration and temperature (including the temperatures of a CGB mixture and its surroundings), in this study a numerical model was developed to predict the development of suction in a CGB mixture containing fly ash. Data from a laboratory study were used to validate the developed model, and it was found that the results of the model simulation and the experimental study were in good agreement. Therefore, the proposed model was applied to simulate and determine the development of suction within the CGB mixture over curing time. The results obtained can contribute to better design and preparation of CGB mixtures, as well as better prediction of the evolution of suction within CGB structures.