Evaluation of short-term strength development of cemented backfill with varying sulphide contents and the use of additives
Evaluation of short-term strength development of cemented backfill with varying sulphide contents and the use of additives
复制标题
评估不同硫化物含量和使用添加剂的胶结回填土的短期强度发展情况
DOI：
10.1016/j.jenvman.2019.03.057
复制
发表时间：
2019-06-01
影响因子：
8.7
通讯作者：
Wang, Hongjiang
中科院分区：
文献类型：
--
作者：
Li, Hong;Wu, Aixiang;Wang, Hongjiang
硫化尾矿的处理和控制硫化物胶结充填体的强度劣化既具有环境意义，又具有经济意义。在短期内评估了不同硫化物含量(6-25wt%)的样品的单轴抗压强度(UCS)。低硫化物试件在14天后强度损失严重，富硫化物试件在28天后继续增加。通过扫描电子显微镜和X射线衍射仪分析，认为膨胀相是导致材料强度失效的主要原因，材料的力学性能与显微组织密切相关。它们被认为对强度产生了从积极到消极的影响。最初，空洞和微孔中的析出物有助于强度发展，直到已经硬化的结构无法承受内部压力，开始出现微裂纹。对于富硫化物胶结充填体，采用缓凝剂和促凝剂两种添加剂，考察了不同硬化过程对胶结充填体机械强度和凝结时间的影响，结果表明，促凝剂使胶结充填体的强度迅速提高，14d后强度急剧恶化。相反，缓凝剂有助于强度的持续增长。从经济角度看，缓凝剂和促凝剂的使用分别占粘结剂成本的6.25%和9.5%。
The disposal of sulphide tailings and control of strength deterioration of sulphide cemented backfills are of both environmental and financial interest. The uniaxial compressive strength (UCS) of samples with varying sulphide contents (6-25 wt%) was evaluated over a short-term period. A severe strength loss occurred after 14 days on those with low sulphide and the sulphide-rich samples keep increasing over 28 days. With SEM and XRD, it was inferred that the expansive phases were presumably responsible for the strength failure and the mechanical performance is closely in relation to the microstructure. They are deemed to present a positive to negative turn of effects on the strength. Initially, the precipitation in voids and micropores contributes to strength development until the already hardened structure cannot bear the inner pressure, microcracks begin to occur. For sulphide-rich cemented backfills, two kinds of additives, set retarder and accelerator, were adopted to measure their effects on the mechanical strength and setting time as the hardening process of cemented backfills was varied, and the results show that the accelerator gave rise to a rapid gain of strength while followed by a sharp deterioration after 14 days. In contrast, the retarder contributes to the continuous strength growth. From the economic perspective, the use of set retarder or accelerator involves 6.25% and 9.5% of binder cost respectively.