Abstract: Influence of the properties of binders on unconfined compressive strength (UCS) of total tailings cemented backfill(TTCB) was investigated.The total porosity and pore size distribution of the samples were measured by using a mercury intrusion porosimeter (Autopore Ⅳ9500）(MIP).The results showed that when the solid concentration of TTCB slurry was respectively 70%,78% and 86% with the binder content of 10% （by total mass of solid）,the UCS of samples with slag cement was respectively 151%,127% and 90% higher than that of samples with 100% portland cement.When the solid concentration of TTCB slurry was 86% and the binder content was 5%,the 7 d,14 d，28 d UCS of samples with slag cement were respectively 68%,97% and 141% higher than that of samples with 100% portland cement.When the solid concentration of TTCB slurry was 86% and the binder content was respectively 5%,10%,20%,30% and 40%,the 28 d UCS of samples with slag cement was respectively 127%,89%,10%,-12% and -21% higher than that of samples with 100% portland cement.Based on MIP data and UCS results,the conclusion was that under the condition of high water-binder ratio（w(W）/w(B)>0.65）,the pore size of the sample with slag cement was finer(i.e.hydration product was more or more dispersing) than that of the sample with 100% portland cement so that the increasing bonding area among aggregates (including powder fill) with slag cement increases the UCS of the sample.Under the condition of low water-binder ratio,the total porosity of the sample with slag cement was greatly higher than that of the sample with 100% portland cement so that the decreasing bonding strength of aggregates (including powder fill) in sample with slag cement lowers the 28 d UCS.

Key words: Total tailings cemented backfill, Property of binders, Water-binder ratio, Unconfined compressive strength, Mercury intrusion porosimeter