Expansive behavior of high-strength self-stressing and self-compacting concrete: Experimental study and analytical model

Abstract

This paper presents an experimental investigation on the expansive behavior of high-strength self-compacting concrete (HSCC) with various HCSA expansive agent (EA) contents ranging from 0 % to 12 %. The fresh properties, compressive strength and expansive ratios at free and restrained conditions are studied. The expansive process and expansive mechanism of self-stressing HSCC are analyzed with a combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. Moreover, the self-stress of expansive HSCC under the confinement of steel-tube is measured. The results show that the compressive strength of HSCC decreases with increasing EA contents, which should not be over 12 % due to the large expansions damage the concrete matrix seriously. The expansive ratios increase significantly with increasing EA contents, as well as increasing amplitudes. The free expansive ratios of concrete can reach 1.08 × 10−4, 3.03 × 10−4, 5.13 × 10−4 and 7.85 × 10−4 with the EA content ranging from 6 % to 12 % at 28 curing days, respectively. Moreover, the self-stresses of expansive HSCC with EA contents of 8–12 % are 3.2–3.7 MPa. Finally, under the framework of plane strain model in elasticity theory, a calculation analytical method is developed to predict the restrained expansive ratios of HSCC confined by steel tubes. The computational formula is also established to calculate the self-stress of expansive HSCC using the axisymmetric plane problems in elasticity. The model formula provides a good description of expansive responses of self-stressing HSCC.