Synthesis and characterization of Nano ashes from different waste materials and their effects on the compressive strength of sustainable concrete: A systematic review

Abstract

Nanotechnology can be regarded as one of the new research fields having novelty and important applications that recently gained attention, especially during the last twenty years. The implementation of nanotechnology produces materials with novel characteristics and recently many works were conducted to include nanoparticles (NPs) in cement-based materials to improve performance and manufacture concrete with better behavior under different mechanical and environmental conditions. Previous studies demonstrated that different waste ashes such as, fly ash, cement kiln dust, palm oil fuel ash, eggshell ash, Metakaolin, and waste ceramic ash can be efficiently converted to sustainable nano ashes. The chemical and physical properties of the produced nano ashes were significantly different from their parent ashes. Therefore, the concrete produced with these nano ashes had superior properties compared to the normal concrete made with traditional waste ashes. This paper presents a systematic overview of the synthesis and characterization of different nano ashes and their impacts on the performance of concrete mixtures. Based on the results from the comprehensive review, it was illustrated that the specific surface to volume ratio was considerably increased by converting the ashes to nano ashes, thus the properties of concrete were also improved. Moreover, due to the higher specific surface area of nano ashes and their reaction with undesirable C-H which is present in the cement paste matrix to produce additional C-S-H, the microstructure of concrete was considerably enhanced.