Concrete is a non-uniform, multi-phase porous material. With the increase in temperature, the chemical configuration of the material changes, and the mortar and coarse aggregate, owing to their different thermal expansions, will produce different thermal stresses, thereby reducing their bonding strength. The thermal and mechanical behaviours of geopolymer concrete that uses geopolymer to replace traditional Portland cement, are different from those of Portland cement concrete in many ways. In order to enable the widespread and safe use of geopolymer concrete (GPC) in construction industry where fire safety is extremely important, this project carried out a systematic study on the thermal and mechanical behaviours of geopolymer concrete at elevated temperatures. The scientific aim of the project is to study the thermal and mechanical behaviours and corresponding failure mechanism of GPC when it is exposed at various different elevated temperatures. The research objectives include:
(1): To develop the stress-strain-temperature constitutive equations of GPC at various elevated temperatures and investigate the effect of temperature on the thermal and mechanical properties of GPC by means of damage mechanics modelling.
(2): To develop 3-phases (gaseous, liquid, solid) and 3-fields (temperature, mass-concentrations of water and water vapour, displacements) finite element coupled analysis (FECA) model to examine the effect of pore pressure on the thermal and mechanical strains and failure mechanism of GPC.
(3): To develop GPC transient strain models to investigate the effect of pre-load on the thermal strain, mechanical compressive strain, and ultimate compressive strength of GPC at various elevated temperatures.
(4): To provide an analysis model for the prediction of fire resistance of GPC when it is exposed in different fire conditions.
(5): To provide training on conducting steady-state tests, transient-state tests, and fire tests of GPC by the host and transfer knowledge from the ER on the multi-phase/multi-scale numerical modelling of concrete structures from his previous research in leading labs in China.
The study includes the effect of temperature on the thermal and mechanical properties of geopolymer concrete and the combined effect of the initial stress and temperature on the constitutive relation of geopolymer concrete at various different temperatures. The research methodology includes the use of advanced experimental testing techniques and multi-physics and multi-phases computer modelling, and the development of theoretical models based on the results obtained from both the experimental and numerical studies. The research creates new knowledge and improve our understanding on the temperature effect on concrete behaviour and performance. The work helps maintain EU excellence in concrete research. The outcome of the project also leads to the development of new types of concrete with targeted performance. This project covers a wide range of disciplines including materials, chemistry, physics, engineering, and computer science. Through the project the individual fellowship has significantly improved his interdisciplinary knowledge and innovative research skills as well as his career development.
