TemGPC

The objectives of the proposed project will be achieved through five integrated work packages (WPs), as shown right:

WP1: Steady-state tests of GPC at various elevated temperatures

Thermal and mechanical behaviours of GPC at various elevated temperatures (OBJ-1) will be investigated using steady-state tests. In each test the GPC cylindrical specimen is first heat to a targeted temperature (without mechanical loading) and then mechanical load is applied until the specimen fails. During the test, the thermal strain as a function of temperature (before the mechanical load is applied) and the mechanical strain as a function of applied mechanical load at the targeted temperature are recorded. Thus, the stress-strain relation at the targeted temperature is obtained.

WP2: Transient-state tests of GPC at various elevated temperatures

Transient-state tests of GPC will be carried out to examine the effect of preload on the thermal and mechanical behaviours of GPC (OBJ-3). In each test the GPC cylindrical specimen with a constant initial stress is heat to a targeted temperature (the initial stress remains unchanged during heating) and then a second mechanical load is applied until the specimen fails. During the test, the thermal strain as a function of temperature and preload (before the second mechanical load is applied) and the mechanical strain as a function of the second mechanical load at the targeted temperature and preload are recorded.

WP3: Coupled heat and mechanical analysis of GPC at elevated temperatures

Finite element analysis model will be developed to simulate the thermal and mechanical behaviours of GPC with both thermal and mechanical loadings. The analysis, including heat transfer and stress analysis, will be carried out using ANSYS, in which the GPC is treated as a composite material made from geopolymer mortar and aggregate and their thermal and mechanical properties are temperature-dependent. The model will be used to re-produce the test results obtained from both steady-state and transient-state tests.

WP3: Coupled heat and mechanical analysis of GPC at elevated temperatures

Finite element analysis model will be developed to simulate the thermal and mechanical behaviours of GPC with both thermal and mechanical loadings. The analysis, including heat transfer and stress analysis, will be carried out using ANSYS, in which the GPC is treated as a composite material made from geopolymer mortar and aggregate and their thermal and mechanical properties are temperature-dependent. The model will be used to re-produce the test results obtained from both steady-state and transient-state tests.

WP4: Fire tests of small scale GPC specimens

Fire tests will be carried out for GPC specimens with and without pre-loading. During the fire test the temperatures in the fire compartment and inside the tested specimen will be recorded as a function of time. The pre-load remains unchanged during a fire test while the total strain-history of the tested GPC specimen is recorded. The objective of the fire test is to obtain the fire resistance of GPC with different pre-loads and to examine the failure mechanism of GPC in fire (OBJ-4). The test results will also be used to validate the computer model developed in WP5.

WP5: Multi-physics and multi-phase modelling of GPC in fire

The heating rate used in the tests in WP1 and WP2 is normally very low (~5oC/min) for which case the effects of temperature gradient in the specimen and the pore pressure build-up inside of concrete on the overall performance of GPC may not be significant. In order to examine the effect of pore pressure on the thermal and mechanical behaviours of GPC a multi-physics and multi-phase finite element analysis model will be developed (OBJ-2) using COMSOL software, in which the concrete is treated as a 3-phase material (gaseous, liquid, solid).