Improving mechanical properties and microstructure of ultra-high-performance lightweight concrete via graphene oxide

This paper aims to use lightweight aggregates to design ultra-high-performance lightweight concrete (UHPLC) via modified Andreasen and Andersen (MAA) model, which is promising to solve the issues on the high density of ultra-high-performance concrete and thus benefits its application in high-rise and long-span structures. To reduce the deadweight of ultra-high-performance concrete, UHPLC was prepared by lightweight aggregates, and its initial mixture was designed according to the MAA model in this study. To improve the mechanical properties and microstructure of UHPLC, the UHPLC developed in this work was modified via the incorporation of graphene oxide (GO). In addition, the micro-mechanical properties of UHPLC paste with/without GO were characterized via nanoindentation technique. Results showed that: (1) Due to the incorporation of GO, the flexural strength, compressive strength and elastic modulus of UHPLC increased by 7.1%–17.7%, 4.4%–21.9%, 4.1%–12.9%, respectively; (2) addition of GO led to a significant enhancement in the internal pore structure of UHPLC; (3) From the perspective of the mechanical properties and microstructure of UHPLC, the optimal content of GO was 0.06 wt%. The findings of this work can offer valuable insights for the fabrication of UHPLC.