A new chemical approach to obtain high early strength in shotcrete

摘要

To increase early compressive strength in wet mixed shotcrete a new two component chemical system has been investigated. This involves the combination of a 'dormant' accelerator, blended with a set consistency control admixture, and a commercial shotcrete accelerator. The effect of the 'dormant' accelerator starts once it is mixed with the shotcrete accelerator. An approximate 100% increase in one hour compressive strength values have been measured in small scale laboratory experiments. Two to three times higher compressive strengths have been measured after three hours, compared to concrete activated only by the conventional shotcrete accelerator. The effect on one day strength was insignificant. The new chemical admixture is a proprietary blend of phosphonates, carbonates, alkanol-amines and hydroxy carboxylates.