Mesoscale Modelling for Investigating Effective Properties and Collective Performance of Geopolymer Concrete

Abstract

Concrete is a versatile construction material which, depending on architectural design and structural analysis, can be shaped into various forms so that requirements for beauty and functions of designed facilities can be met while structural strength of the facilities is sufficient to sustain both gravity and external loadings. It is so favoured by engineers that its consumption is just after water. However, Portland cement – a main ingredient for use in the manufacture of traditional concrete – is quite a “dirty” material which releases a large amount of carbon dioxide in the process of its production. Carbon dioxide is one of the greenhouse gases causing global warming which may be a main factor behind extreme heatwaves seen in the UK and around the world in recent years. To reduce the impact of construction on environment, scientists and engineers are trying their best to propose and investigate novel sustainable materials for the production of concrete.
Geopolymer is an inorganic aluminosilicate material which has been conclusively proven in numerous studies to be a greener and more sustainable binder as compared to Portland cement. This elevates attention from many researchers on using it to partially or completely replace Portland cement in the manufacture of concrete products. In order to accelerate applications of geopolymer and widen the industrial utilisation of geopolymer concrete, more research is in dire need of understanding properties and behaviour of geopolymer concrete. Aim of this research is to propose a cost-effective mesoscale modelling technique to predict effective thermal and mechanical properties of geopolymer concrete, and to investigate the collective performance of geopolymer concrete subjected to both thermal and mechanical loadings. With this aim in mind, work of this research is divided into the following six research objectives. (1) To propose a generic mathematical algorithm and develop the MATLAB codes for building up the mesoscale geometric models of geopolymer concrete with realistic and theoretical shapes of aggregate; (2) To predict the effective mechanical properties of geopolymer concrete at ambient temperature using the technique of the proposed mesoscale modelling and then to investigate the damage behaviour of geopolymer concrete subjected to uniaxial compression; (3) To investigate possible factors that may affect the collective performance of geopolymer concrete by means of carrying out parametric analysis on the mesoscale models. (4) To predict the effective thermal conductivity, a property for evaluating the heat transfer capacity of geopolymer concrete, by means of mesoscale modelling; (5) To apply mesoscale modelling to calculate the effective coefficient of thermal expansion of geopolymer concrete; and finally (6) To investigate the coupled behaviour of geopolymer concrete subjected to both thermal and mechanical loadings from the mesoscopic point of view.
Results show that the developed codes are capable of generating different types of mesoscale geometric models of geopolymer concrete and the proposed mesoscale modelling technique can well predict thermal and mechanical properties of geopolymer concrete. It is also revealed that this technique can be well applied to investigate the thermo-mechanical behaviour of geopolymer concrete. Based on the contributions demonstrated in this thesis, further research can be carried out to evoke more understanding of geopolymer concrete and boost our confidence in use of geopolymer concrete in more construction structures.

Date of Award	2025
Original language	English
Awarding Institution	University of Plymouth
Supervisor	Long-yuan Li (Director of Studies (First Supervisor)) & Shanshan Cheng (Other Supervisor)