Influence of curing conditions on mechanical and microstructural properties of ultra-high-performance strain-hardening cementitious composites with strain capacity up to 17.3%

Abstract

This study investigated the mechanical properties and microstructural characteristics of ultra-high-performance strain-hardening cementitious composites (UHP-SHCC). The mechanical properties were thoroughly analyzed based on the shrinkage behavior, thermogravimetric analysis, mercury intrusion porosimetry, and scanning electron microscopic images. Three relative humidity (RH) conditions and curing ages were set as the test variables. Relative to the specimens cured at 30% RH, the specimens cured at 60% and 100% RH conditions showed 29.9% and 37.6% higher 91-day compressive strengths. Excellent strain-hardening behaviors with very high strain capacities, ranging between 6.0% and 17.3%, were obtained for all UHP-SHCC specimens tested. The highest strain capacity and energy absorption capacity of 17.3% and 1310.7 kJ/m3 were obtained when cured under RH conditions of 30% and 60% for 7 days, respectively. The strain capacity and energy absorption capacity of UHP-SHCC rather decreased as the RH condition and curing age increased to 100% and 91 days, respectively.