Enhancing mechanical and thermal performance of EPS lightweight concrete using condensed silica fume for sustainable building applications

Condensed silica fume (CSF), a highly reactive pozzolanic material, is produced as a by-product of silicon and ferrosilicon alloy manufacture. It is well known for its high silica content and ultra-fine particle size, which make it useful for improving the cement performance. The present study aims to investigate the impact of CSF on the properties of lightweight concrete composites (LWC). CSF was utilized to partially replace cement by up to 8 wt% in order to improve the strength properties of LWC. To produce LWC with a density of 800-900 kg/m3, recycled expanded polystyrene foam (re-EPS) was incorporated at 53 Vol% of the total LWC volume. Compressive strength, density, thermal conductivity, and time lag were investigated. The results indicated that the compressive strength of LWC blended with CSF increased significantly at early ages, while the density was notably lower than that of the control LWC. Although the thermal conductivity did not significantly change with increasing CSF content, all values remained within the acceptable range for insulating materials. In addition, the re-EPS lightweight concrete containing CSF demonstrated a longer time lag in heat transfer from the exterior to the interior of the building wall, which potentially improving energy efficiency for building applications.