Performance of rice husk Ash-Based sustainable geopolymer concrete with Ultra-Fine slag and Corn cob ash

Abstract

This paper presents the first scientific attempt to develop and study the performance of rice husk ash (RHA) and ultra-fine slag (UFS) based sustainable geopolymer concrete with different ratio of corn cob ash (CCA). NaOH (8 M) and Na2SiO3 were employed as alkaline activators. CCA acted mainly as amorphous silica and was utilised as a substitute for RHA. The effects of different CCA contents (0%, 3%, 6%, 9% and 12% by RHA mass) on the performance of geopolymer concrete in terms of fresh, hardened and durability properties have been evaluated. Different characteristics, i.e. density, air content, workability, compressive, flexural and split tensile strengths, Young’s modulus of elasticity were investigated. Meanwhile, the durability performance was also evaluated by using different methods such as rapid chloride penetration test, chloride conductivity test, water sorptivity test and DIN (Deutsches Institut für Normung) water permeability test. The outcomes of this research have shown that UFS and CCA improved the compressive strength by 14–15%. They significantly improved the polymerisation and thus enhanced the strength and durability of sustainable geopolymer concrete. Furthermore, CCA and UFS acted as micro fillers and increased the CaO as well as SiO2 contents which enhanced the densification. Additionally, the development of hydration products in the matrix, enhanced the pore structure and thus the strength. This study revealed that CCA (up to 6%) can be utilised as a substitute binder to produce sustainable geopolymer concrete, and has the potential to replace conventional concrete for structural applications.