Microporous structures and compressive strength of high-performance rubber concrete with internal curing agent

Abstract

Abstract Pore structure characteristics and their influence on the compressive strength of a high-performance rubber concrete (HPRC) with three different molecular weight super-absorbent polymers (SAPs) were investigated with mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). The test results from the MIP and SEM analyses show that the total porosity of the HPRC increases by 3.45% when the rubber content is 5%, and the addition of the SAP can also increase the total porosity of the HPRC. There is a positive correlation between the total porosity and the molecular weight of the SAP, and the porosity with a high molecular weight SAP (20 million) increases by 13.56%. The amount of small pores with a size of 10–100 nm is mainly controlled by the rubber content, while the addition of SAP mainly controls the percentage of large pores with a size range of 100–1000 nm and macropores over 1000 nm. The pore size increases along with an increase in the SAP molecular weight. The compressive strength test results show that the internal curing agents can increase the compressive strength of the HPRC, and the compressive strength first increases and then decreases with an increase in the molecular weight of the SAP.