Mechanical Properties and Microstructure of High-Strength Lightweight Concrete Incorporating Graphene Oxide

The increasing demand for high-strength lightweight concrete (HSLWC) with excellent mechanical properties has inspired the development of nanomaterials in fundamentally solving brittleness and cracking. This work investigated the effects of graphene oxide (GO) on the mechanical properties and microstructure of HSLWC, including the workability, density, compressive strength in different curing regimes, splitting tensile strength, flexural strength, modulus of elasticity and scanning electron microscopy (SEM). Six groups of mixtures were mixed with GO aqueous solution at a dosage of 0.00%, 0.02%, 0.04%, 0.05%, 0.06%, and 0.08% by weight of cement, respectively, and dispersed by ultrasound for 30 min. The test results showed that adding a low volume of GO to the specimens could slightly increase the density, rationally reduce the slump, and significantly improve the mechanical properties. The maximum increase in compressive strength, splitting tensile strength, modulus of elasticity and flexural strength of HSLWC with GO at 28 days was by 24%, 17%, 15%, 20%, respectively, as compared with HSLWC without GO. Simultaneously, the SEM results showed that GO could not only fill nano-scale pores, but also regulate the formation and growth of flower-like crystals, which was an important factor for the further improvement of properties. The research results provided a potential new pathway to improve the mechanical properties of HSLWC.