On November 12, 2024, Professor Guohao Fang research group published a research paper titled "Effect of nano-silica on mechanical properties and microstructure of engineered geopolymer composites" in the Journal of Cement and Concrete Composites (JCR Q1). The research explores the effects of nano-silica (SiO₂) on the relationship between the microstructure and mechanical properties of engineered geopolymer composites (EGC). Professor Fang is the corresponding author, Shenzhen University is the first completion unit.

This study systematically evaluated the feasibility of incorporating nano-silica (NS) particles to address the problem of balancing strength and ductility in EGC, aiming to develop EGC with extraordinary mechanical properties. The relationship between microstructure and mechanical properties of NS-EGC was studied via X-ray computed tomography (XCT) and backscattered electron microscopy (BSEM) tests, to gain an in-depth understanding of the obtained properties. Results indicate that NS-EGC mixes with superior compressive and tensile behaviour were successfully fabricated based on micromechanics design theory. The optimal NS content and particle size were 1 % and 15 nm, where the resulting composite outperformed all proposed EGC in terms of compressive strength (94 MPa), tensile strength (9.17 MPa) and tensile strain capacity (9.06 %). The mechanical properties of NS-EGC were strongly dependent on the pore structure, fibre orientation and fibre dispersion, where these microstructural effects can be modified by NS. This study provides a new approach to optimising the strength-ductility balance of EGC through nano-silica incorporation, offering the potential for broadening the application of EGC in high-performance structural materials.

This research was supported by the National Key Research and Development Program, National Natural Science Foundation and Shenzhen Key Laboratory for Low-carbon Construction Material and Technology. The original article can be found at:

https://doi.org/10.1016/j.cemconcomp.2024.105849

Fig.1. NS-EGC with high-strength and extraordinary tensile ductility.