The mechanical properties and microstructure of ultra-high-performance concrete containing various supplementary cementitious materials

Abstract

The present study investigated the mechanical properties and microstructure of ultra-high-performance concrete (UHPC) containing supplementary cementitious materials (SCMs). The investigation was attempt to partially replace cement up to 50% with SCMs, including limestone powder (LSP), rice husk ash, silica fume (SF) and kaoline (KL), and to verify the synergistic effect in ternary and quaternary system. On the basis of 30% LSP replacement, the incorporation of either 20% SF or 10% KL and 10% SF showed better mechanical properties. Results also indicated that with the similar chemical composition, the physical characteristics of SCMs had a significant effect on flexural and compressive strength. Efficiency factor (k value) was calculated as an indicator to predict the compressive strength of UHPC with these SCMs in terms of their synergistic effects. The microstructure observed from scanning electronic microscopy and pore volume measured based on BJH method indicated a high correlation with compressive strength.

Keywords:

• ultra-high-performance concrete
• supplementary cementitious materials
• mechanical properties
• microstructure
• limestone powder