煅烧硬质高岭土对铅锌矿溢流尾砂胶结膏体充填材料抗压强度的影响

对煅烧硬质高岭土对铅锌矿溢流尾砂胶结膏体充填材料抗压强度的影响进行了研究。研究结果表明:当胶结剂中煅烧硬质高岭土(Calcined Hard Kaolin,CHK)取代水泥率从0增加到30%时,胶结膏体充填材料(Cemented Paste Backfill,CPB)28d抗压强度基本保持不变;当CHK取代水泥率从30%增加到80%时,CPB的28d抗压强度急剧降低;当CHK取代水泥率低于50%的CPB养护到28d或56d后,其抗压强度大幅度降低;当CHK取代水泥率为50%的CPB养护到180d时,其抗压强度呈增长趋势。CPB抗压强度损失与其内部形成膨胀性物质(石膏)有关。当CHK取代水泥率为50%时,由于降低了胶结剂中水泥熟料的量,CHK中偏高岭土(Metakaolin,MK)和水泥水化产物氢氧化钙的火山灰反应解除或减少了膨胀性二水石膏的形成,结果CPB的180d抗压强度呈增长趋势。

Influence of calcined hard kaolin on the compressive strength of Cemented Paste Backfill of lead-zinc mine overflow tailings

In this paper, the influence of calcined hard kaolin (CHK) on the Unconfined Compressive Strength (UCS) of cemented paste backfill (CPB) of lead-zinc mine overflow tailings are studied. The results show that when CHK replace cement rate from 0 to 30%, the 28 d UCS of CPB samples nearly remain unchanged; when CHK replace cement rate from 30% to 80%, the 28 d UCS of CPB samples sharply decrease; when CHK replace cement rate less than 50%, the UCS of CPB samples substantially decrease after curing 28 d or 56 d; when CHK replace cement rate up to 50% for curing 180 d, the UCS of CPB samples show a trend of growth. The strength losses of CPB samples can be associated with the formation of expansive gypsum (CaSO4?2H2O). When CHK replace cement rate up to 50%, the cement clinker in binder is decreased and the pozzolanic reaction between the Metakaolin (MK) in the CHK and calcium hydroxide release during the hydration of OPC consumes port of the calcium hydroxide to remove or reduce the formation of expansive gypsum so that the 180 d UCS of CPB samples show a trend of growth.