Study of using Coal Fly Ash (CFA) and Rice Husk Ash (RHA) on the Compressive Strength of Geopolymer Concrete

¹ Civil Engineering Department, Faculty of Engineering, Bina Nusantara University, Jakarta, Indonesia 11480
² Agrotechnology Department, Faculty of Agriculture, INSTIPER Agriculture University, Yogyakarta, Indonesia
³ Research Center for Sustainable Production System and Life Cycle Assessment, The National Research and Innovation Agency of The Republic of Indonesia, Banten, Indonesia
⁴ College of Science, Health, Engineering and Education, Murdoch University, Murdoch, WA, 6150, Australia

^* Corresponding author: yureana.wijayanti@binus.ac.id

Abstract

Concrete is a material that is widely used in the construction world. The production of Portland cement in concrete leads to CO₂ emissions that have an impact on global warming. Geopolymer Concrete is an eco-friendly material because it does not use Portland cement. Geopolymer cement is made from waste materials such as fly ash (FA) by alkali activation. In geopolymer, sodium silicate is a commonly used activator that is produced commercially. In this study, rice husk ash (RHA) from agricultural waste was used as an activator for geopolymer cement. The objective of this study is to review the chemical component of FCA and RHA and, to examine the effect of RHA in geopolymer concrete mixed design on the compressive strength. The geopolymer concrete binder is using 12 M NaOH and Na₂SiO₃, with variations for RHA 0%, 5%, 7.5%, and 10%. The specimens were treated for 28 days, curing in a 70oC oven for 24 hours then curing at ambient temperature. The result shows that geopolymer concrete has a higher compressive strength compared to ordinary Portland cement (OPC) as much as a 5.9 MPa difference with geopolymer concrete of RHA10% of 25 MPa.