Effect of Internal Curing of SAP on Properties of Alkali-Activated Slag Cementitious Materials

Abstract

Abstract: Alkali-activated slag (AAS) cementitious materials have the problems of large early shrinkage and high cracking risk, which limit their engineering applications. In this study, superabsorbent polymer (SAP) was used as internal curing material to investigate its influence on the hydration heat, hydration products and pore structure of AAS cementitious materials by means of TAM, TGA and MIP, respectively. Moreover, the effect of SAP on the compressive strength and autogenous shrinkage of AAS cementitious materials were also studied. The results show that the addition of SAP increases the porosity of the matrix, and thus results in the decrease of compressive strength of AAS pastes. With the extension of hydration time, the internal curing effect of SAP promotes the hydration of slag, and the strength reduction is slightly compensated. The addition of SAP has a delay effect on the hydration exothermic process, which prolongs the induction period and leads to the lagging of the second exothermic peak. Furthermore, internal curing of SAP increases the content of hydration products, particularly for AAS pastes with higher modulus. The autogenous shrinkage of AAS pastes with SAP are obviously reduced compared with that of reference samples, and the maximum autogenous shrinkage reduction rate is reached up to 81%.

Key words: cementitious material, alkali-activated slag, internal curing, superabsorbent polymer, mechanical property, hydration property, autogenous shrinkage

CLC Number:

TQ177

LI Xiangguo, XU Jinsheng, JIANG Dongbing, LYU Yang, HE Chenhao, ZHANG Cheng, FU Qiuyan. Effect of Internal Curing of SAP on Properties of Alkali-Activated Slag Cementitious Materials[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2021, 40(10): 3435-3441.

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