Effects of plastic expansive agent on the fluidity, mechanical strength, dimensional stability and hydration of high performance cementitious grouts

Abstract

In this paper, the influences of plastic expansive agent (PEA) on the fluidity, mechanical strength, and dimensional stability of high-performance cementitious grouts were studied. The hydration of the grouts was also evaluated by XRD, TG-DSC and SEM analyses. The results show that with its dosage variation, PEA greatly affects the fluidity, mechanical strength, and dimensional stability of cementitious grout. PEA can bring slight fluidity decrease of the grout, with negligible influence of its dosage variation. PEA can improve the flexural strength and compressive strength at smaller dosages, while brings a dramatical decrease at higher dosages. With its dosage increasing, PEA greatly improves the vertical expansion rate, accordingly to assume grouts excellent early-aged dimensional stability, but brings the increase of the drying shrinkage. XRD, TG-DSC and SEM analyses indicate that PEA has negligible influence on the hydration of grouts, but may bring much denser and bigger hydrates and more pores in grouts to assume joint impact on properties. Consequently, there exists an optimum dosage range for PEA in cementitious grouts to ensure grouts with good fluidity, high strength and excellent dimensional stability.