Degree Name

Doctor of Philosophy


School of Civil and Mining Engineering


Geopolymer materials (pastes, mortars and concretes) are formed through the activation of aluminosilicate sources with an alkaline solution, and can achieve a comparatively similar or superior performance to ordinary Portland cement (OPC). Given that these aluminosilicate materials can be industrial by-products such as fly ash and slag, geopolymer materials are green, economical and sustainable materials. Geopolymer materials have also become more globally popular as an alternative to OPC by greatly reducing the emission of CO2, as OPC requires much higher energy and temperature to be produced. Although the properties of geopolymer concrete used in structural members have already been relatively well researched, this study aims to investigate the feasibility of geopolymer concrete used in pavements and piles. This study expands the use of geopolymer materials in practice, while reducing the consumption of OPC as much as possible. In order to fulfill the objectives of this study, three groups of experiments have been carried out and the corresponding mathematical models were proposed to simulate them.

The first part of this research study is concerned with the optimum mix proportion of geopolymer pastes and concretes. Twenty-eight mixes of geopolymer paste were conducted at ambient curing conditions to find the optimum mix proportion. The influences of ground granulated blast furnace slag (GGBFS) content, alkaline solution to binder (Al/Bi) mass ratio, sodium silicate solution to sodium hydroxide solution (SS/SH) mass ratio, and additional water to binder (Aw/Bi) mass ratio on compressive strength, setting times and workability were investigated. The optimum mix proportion was found to have GGBFS content of 40%, Al/Bi ratio of 0.5, SS/SH ratio of 2.0, and Aw/Bi ratio of 0.15. Next, regression models by considering GGBFS content, Al/Bi, SS/SH, Aw/Bi and artificial neural network (ANN) models by considering molar ratios of SiO2/Al2O3, H2O/Na2O, Na2O/SiO2, CaO/SiO2 were proposed to predict the experimental results.

FoR codes (2008)




Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.