Microstructure, durability and mechanical properties of high strength geopolymer concrete containing calcinated nano-silica fume/nano-alumina blend

Abstract

This study investigates the enhancement of green architecture by using materials with reduced environmental impact compared to conventional concrete, especially due to the global environmental concerns associated with cement production. Geopolymer concrete has emerged as a sustainable alternative due to its favorable environmental properties, and recent efforts focus on further improving its durability and mechanical performance through nanomaterials additives. In this research, an examination on the effects of nano-silica fume and nano-alumina, in both physical mixed and calcinated physical forms, on the microstructural, mechanical properties and durability of high-strength geopolymer concrete. The experimental work introduces a comparative study between nano-silica fume and nano-alumina blend in their physically mixed form and those subjected to calcination at temperatures of 600°C, 800°C, and 1000°C for eight hours. Mechanical properties evaluated include compressive, tensile, and flexural strength, alongside durability indicators such as sorptivity, water absorption, and acid resistance attack. Results demonstrate that blends of nano-silica fume and nano-alumina in both forms exhibit synergistic effects, yielding notable improvements in mechanical strength. Calcination at 800°C was identified as the optimal temperature for maximizing these performance gains. The refined microstructure achieved with nanomaterial additives, particularly nano-silica fume, significantly reduced water sorptivity and enhanced acid resistance, indicating improved durability. These findings highlight the potential of high strength geopolymer concrete containing the used nano-materials in sustainable construction applications.