Abstract In this research, the effect of curing temperature on the Arsenic (As(III)) leachability of cemented paste backfill (CPB) that contains blast furnace slag (OPC/Slag-CPB) are studied. ASTM C 1308 leaching protocol is adopted to assess the leachability of OPC/Slag-CPB specimens cured at various temperatures (2 °C, 20 °C and 35 °C). Furthermore, various microstructural techniques are used to relate the temperature-induced changes in the microstructural properties of the OPC/Slag-CPBs to their leaching characteristics. The results show that leaching of arsenic from OPC/Slag-CPB is temperature dependent. Higher curing temperature leads to a decrease in the amount of arsenic released from the OPC/Slag-CPB. The As leachability-decreasing factors are: (i) faster cement hydration rate and pozzolanic reaction with higher curing temperatures, which increase the volume of As immobilizing phases (C-S-H, CH, ettringite) in the OPC/Slag-CPB; (ii) lower volume of connective pores (smaller connective pore surface area) with higher curing temperatures, which decreases the area of reaction sites, thereby reducing the mobility of arsenic. Leaching of As from OPC/Slag-CPBs is dominated by diffusion, irrespective of the curing temperature. Results also reveal that CPBs with ordinary Portland cement (OPC) leach significantly less than CPBs with OPC and Slag (50/50) for all curing temperatures. However, curing temperature has the opposite effect on the OPC/Slag-CPBs compared to OPC-CPBs. OPC is suggested as a binder in situations where the principal design parameter is immobilizing As(III) in CPB subjected to various thermal curing conditions. The results indicate that curing temperature is a critical variable to consider when assessing the ability of CPB structures to release arsenic into the underground environment.

中文翻译：

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含有高炉矿渣的胶结膏体回填的非金属浸出性的热致变化

摘要 在本研究中，研究了固化温度对含有高炉矿渣（OPC/Slag-CPB）的水泥膏体回填（CPB）的砷（As（III））浸出性的影响。采用 ASTM C 1308 浸出协议来评估在不同温度（2°C、20°C 和 35°C）下固化的 OPC/Slag-CPB 试样的浸出性。此外，各种微结构技术用于将温度引起的 OPC/Slag-CPBs 微结构特性的变化与其浸出特性联系起来。结果表明，从 OPC/Slag-CPB 中浸出砷与温度有关。较高的固化温度导致从 OPC/Slag-CPB 释放的砷量减少。降低 As 浸出性的因素是：(i) 水泥水化速率和火山灰反应更快，固化温度更高，增加 OPC/Slag-CPB 中 As 固定相（CSH、CH、钙矾石）的体积；(ii) 固化温度越高，连接孔的体积越小（连接孔表面积越小），这减少了反应位点的面积，从而降低了砷的迁移率。无论固化温度如何，从 OPC/Slag-CPB 中浸出 As 主要是扩散。结果还表明，对于所有固化温度，具有普通硅酸盐水泥 (OPC) 的 CPB 的浸出量明显低于具有 OPC 和矿渣 (50/50) 的 CPB。然而，与 OPC-CPBs 相比，固化温度对 OPC/Slag-CPBs 的影响相反。在主要设计参数是在各种热固化条件下将 As(III) 固定在 CPB 中的情况下，建议将 OPC 作为粘合剂。