Experimental study of the shrinkage behavior of cemented paste backfill

Cemented paste backfill (CPB) is largely used in underground mine stopes worldwide. When a CPB is placed in a stope, an important task is to estimate the settlement associated with the shrinkage and selfweight consolidation of the CPB. This is closely related to the volume management to ensure the stability of barricades and tight contacts between the backfill and stope roof. Over the years, shrinkage studies were mostly performed on fine-grained soils (silts and clays), with only a few publications on the shrinkage behavior of uncemented tailings. No study has been published on the shrinkage behavior of CPB. To fill this gap, a series of shrinkage tests has been conducted on CPB with different cement contents, including zero cement content (uncemented paste backfill, uCPB). The results show that the shrinkage response of CPB is very different from that of uCPB. At a given initial water content, CPB exhibits a shorter normal shrinkage stage than uCPB. The unsaturation onset water content and void ratio, shrinkage limit and final void ratio of CPB are generally higher than those of uCPB. At a given cement content, the shrinkage behaviors of CPB and uCPB are significantly influenced by the initial water content. (C) 2021 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V.