Influence of binder content on temperature and internal strain evolution of early age cemented tailings backfill

The philosophy of the use of backfill is to return much of tailings waste to underground voids and increase working place stability to safely extract more minerals. The key issue for the safe and efficient design of cemented tailings backfill (CTB) structure is its mechanical properties and interaction with the surrounding rock. As a cemented material, CTB's strength is a function of hydration degree. As hydration is an exothermic reaction and results in net volume reduction, thermal expansion and chemical shrinkage occur simultaneously in the mixture. Each CTB component plays a significant role during this process and the most important factor is the binder content, because it influences the amount of cement hydration products that provide binding phases between tailing particles. In this paper, a number of fiber Bragg gratings (FBGs) were directly embedded into the 7-day cured CTB specimens to measure their temperature and internal strain evolution, with settlement development measured by Linear Variable Differential Transformer (LVDT). The experimental results showed that binder content had a significant effect on CTB temperature and internal strain evolution. Furthermore, the evolution of internal strain and settlement was an indicator of the transformation in different stages (such as fluid, skeleton formation and hardening) during the hydration process.