Yin, S, Shao, Y, Wu, A, Rao, Y & Chen, X 2017, 'Deformation behaviors of cemented backfill using sulphide-content tailings', in A Wu & R Jewell (eds), Paste 2017: Proceedings of the 20th International Seminar on Paste and Thickened Tailings, University of Science and Technology Beijing, Beijing, pp. 315-327, https://doi.org/10.36487/ACG_rep/1752_35_Yin (https://papers.acg.uwa.edu.au/p/1752_35_Yin/) Abstract: The deformation properties of cemented tailings backfill (CTB), especially prepared from sulphidic tailings, are valuable for the estimation of design parameters for underground stope filling as well as for numerical simulation. In this paper, the effect of curing time, sulphur content, cement dosage and solids concentration on the free expansion ratio of CTB specimens was investigated using an invented lab apparatus called “free expansion measuring instrument”. The backfill recipe (sulphur content, binder dosage and solids concentration) and curing days had significant influences on the expansion performance of the CTB. The results indicated that with the change of sulphides, the free expansion ratio (FER) showed no obvious growth at the curing of 28 days. However, after the curing of 120 days, FER increased from 4.96% (S: 4%) to 9.61% (S: 20%). As the solids concentration increased, the FER also rised. And this growth was distinctive only when the solids concentration is relatively high (65~75%) and at the long-term curing time (120 days). The proportions of binder and the obtained FER clearly show a sub-linear and proportional relationship. Increasing the amount of binder (8~16%) could not restrict the increment of expansion ratio, and ultimately the CTB specimens would generate cracks and collapse.