Doctor of Philosophy (PhD)
Civil and Environmental Engineering
With the current demand for Portland cement concrete (PCC) sustainability, supplementary cementitious materials (SCMs) are used in concrete mixtures. The SCMs positively impact the environmental and economic aspects of concrete mixtures and improve the mixture properties in both fresh and hardened concrete. In this research, one control and twenty-four ternary mixtures, with various combinations of fly ashes (Class C and F), slags (Grade 100 and 120), and Portland cement were fabricated. The thermal properties (coefficient of thermal expansion (CTE), thermal conductivity, and heat capacity) and mechanical properties of the selected ternary mixtures were measured at various ages. Temperature gradients were measured using a concrete pavement (10-in. thick) to characterize daily and seasonal temperature variations through the slab thickness. The correlation between air temperature and surface temperature, as well as air temperature and temperature difference of the slab thickness, were established based on the measured temperature gradients in the concrete pavement. The enhanced integrated climatic model (EICM) analysis was conducted, using measured material properties and climatic conditions. A local calibration of EICM was performed by comparing EICM-predicted temperature gradients to field measurement. It was concluded that the surface temperature is suitable to accurately predict temperature gradients in EICM. A thermal stress analysis of the ternary mixtures was conducted to calculate the critical tensile stress on the PCC pavements by means of the measured mechanical properties, nonlinear temperature gradients obtained from EICM, and CTE gradients throughout the slab thickness. The ratios of tensile stress-to-strength at the critical state of concrete pavements were estimated as well, in order to investigate the vulnerability of ternary mixtures to tensile stress. The ratio of tensile stress-to-strength shows that all the ternary mixtures, inclusive of the replacement of 30 % slag with 20 % fly ashes, 30 % slag with 30 % fly ashes, and 50 % slag with 20 % fly ashes (both Class C and F), do not exceed 100 % tensile stress-to-strength ratio at all ages. These combinations may be considered as the limitation of ternary mixture replacement with slags and fly ashes.
Document Availability at the Time of Submission
Release the entire work immediately for access worldwide.
Chung, Yoonseok, "Thermal stress analysis of jointed plain concrete pavements containing fly ash and slag" (2012). LSU Doctoral Dissertations. 2608.