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| Influence of calcined hard kaolin on the compressive strength of CPB of lead-zinc mine overflow tailings |
| Received:July 17, 2016 Revised:July 23, 2016 |
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| DOI： |
| KeyWord:cemented paste backfill of lead-zinc mine overflow tailings; calcined hard kaolin; unconfined compressive strength; gypsum |
| Author | Institution |
| Zheng |
郑州大学土木工程学院 |
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| Abstract: |
| 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 were studied. The results showed that when CHK replaced cement rate from 0 to 30%, the 28 d UCS of CPB samples nearly remain unchanged; when CHK replaced cement rate from 30% to 80%, the 28 d UCS of CPB samples sharply decreased; when CHK replaced cement rate less than 50%, the UCS of CPB samples substantially decreased after curing 28 d or 56 d; when CHK replaced cement rate up to 50% for curing 180 d, the UCS of CPB samples showed a trend of growth. The strength losses of CPB samples can be associated with the formation of expansive gypsum (CaSO4·2H2O). When CHK replaced cement rate up to 50%, the cement clinker in binder was decreased and the pozzolanic reaction between the metakaolin (MK) in the CHK and calcium hydroxide released 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 showed a trend of growth. |
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