Comprehensive evaluation of mechanical, durability, and microstructural properties of foamed concrete with zinc...

The incorporation of nanoscale elements into concrete has attracted significant interest due to their unique characteristics. Nanoparticles, owing to their small size and high reactivity, can notably improve the properties of foamed concrete (FC) by occupying voids and enhancing its overall performance. This study investigates the impact of zinc peroxide nanoparticles (ZP-NP) on FC, focusing on thermal and mechanical properties, density, setting time, workability and shrinkage. FC mixes were formulated with ZP-NP concentrations ranging from 1 wt% to 4 wt%. Key experimental results revealed that the addition of ZP-NP increased the thermal conductivity, from 0.313 W/m·K to 0.345 W/m·K (2 wt% ZN-NP). Mechanical properties such as flexural, splitting tensile and compressive strengths also showed notable improvements with the optimal concentration of 2 wt% ZN-NP. Specifically, compressive strength increased by 55.62% after 28 days and 60.92% after 56 days compared to the control mixture. The splitting tensile strength increased by 62.5% after 7 days and 61.90% after 56 days, while flexural strength showed a 66.17% increase after 7 days and 59.75% after 28 days. Dry density increased by 5.3%, and porosity was reduced by 6.66% at the 2% ZP-NP concentration. However, at higher ZP-NP concentrations, the improvements plateaued, and a slight reduction in strength and porosity occurred, likely due to nanoparticle agglomeration and zinc leaching. Scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) revealed a denser microstructure and a reduction in pore size, contributing to enhanced material properties. These findings demonstrate that ZP-NP can significantly enhance the mechanical and thermal properties of FC, optimize the pore structure, and improve overall performance, with the most pronounced effects observed at a 2% ZP-NP concentration.