The effect of SCMs and SAP on the autogenous shrinkage and hydration process of RPC

Abstract

To investigate methods to overcome the high autogenous shrinkage of reactive powder concrete (RPC), supplementary cementitious materials (SCMs) in conjunction with internal curing (IC) by means of superabsorbent polymer (SAP) were employed in this research. The autogenous shrinkage deformation, mechanical properties, heat of hydration, and thermal analysis of various RPC mixes incorporating these materials were investigated and compared. The results indicated that autogenous shrinkage decreases with the increase in SCMs, and IC by means of SAP was proven to successfully mitigate autogenous shrinkage. While the mechanical strength was determined to somewhat deteriorate as a result of the addition of SCMs, the compressive strength still remained higher than 110MPa at 28days, even with a cement replacement level by SCMs of up to 50%. The hydration temperature peak occurred later with the addition of SCMs, and its peak value decreased with the increase in SCMs. The degree of hydration of the RPC increased with the increase in the water-to-binder ratio, and decreased with the increase in SCMs. The autogenous shrinkage of RPC was shown to be mitigated by the inclusion of SCMs and IC, the combination of which is can sufficiently mitigate serious autogenous shrinkage deformations and provide an environmental friendly and economical way to produce RPC.