Yin, SH, Zhang, M, Wang, LM & Chen, W 2024, 'Mechanical behaviours and backfilling performance of cemented tailings-waste rock backfill with various superplasticisers: an experimental study', in AB Fourie & D Reid (eds), Paste 2024: Proceedings of the 26th International Conference on Paste, Thickened and Filtered Tailings, Australian Centre for Geomechanics, Perth, pp. 571-584, https://doi.org/10.36487/ACG_repo/2455_45
(https://papers.acg.uwa.edu.au/p/2455_45_Zhang/)
Abstract: Cemented paste backfill (CPB) is an artificial product that exhibits superior mechanical properties. The compressive strength and fluidity of CPB are critical design factors that affect its backfilling performance. However, the maldistribution of backfill strength and poor slurry fluidity are still major problems for the backfilling of mined-out area in Jinchuan nickel mine. In this paper, four types of superplasticisers, polycarboxylate- (PC-P), naphthalene- (FDN), aliphatic- (AK) and melamine-based (SM), were investigated to analyse the mechanical behaviour of CPB with tailings-waste rock (TW). Firstly, primary focus was on the proportioning test of CPB-TW, and an optimal ratio was subsequently determined for the optimisation test of superplasticisers. The findings demonstrated that CPB-TW had optimal backfilling performance as the cement-sand ratio was 1:4, slurry concentration was 77%, and the amount of waste rock (WR) was 60%. Under this condition, the specimen had the highest unconfined compressive strength (UCS) values of 1.17 MPa and 5.03 MPa at three and 28 days, respectively. The superplasticisers dosage ranged from 0.15 to 1.2% (by mass of cements) and was subjected to the above-optimised CPB-TW slurry to test the setting time, slump evolution, microstructure, and UCS. Test results indicated that the appropriate superplasticisers can effectively improve the free water distribution in CPB-TW slurry and facilitate the transportation of slurry in the backfilling pipeline. Otherwise, excessive addition of superplasticisers will significantly degrade the backfilling performance of CPB-TW. Comprehensively, CPB-TW with PC-P (cement content × 0.35%) had the optimal slurry slump, UCS, and the better coagulation performance, which is conducive to the pipeline transportation of backfilling slurry.

Keywords: mechanical behaviour, backfilling performance, cemented paste backfill, pipeline transportation, superplasticisers