Title: CO2-Optimal Design of Fly Ash Marine Concrete with Global Warming and Stress Types
Author(s): Xiao-Yong Wang
Publication: Materials Journal
Appears on pages(s): 91-102
Keywords: chloride penetration; CO2 emissions; costs; fly ash-blended concrete; mixture design; optimization; sustained stress
Concrete with fly ash is commonly used in the infrastructures of marine regions. However, the traditional design method does not account for the influences of sustained stress and global warming. This research presents an optimized design approach for low-CO2 marine concrete with fly ash considering chloride penetration with stress and global warming. First, the purpose of optimal design is sustainability (the embodied CO2 of concrete). The constraints of optimization consider strength, slump, and chloride penetration durability with the effects of stress and global warming. Second, a global optimization algorithm, named a genetic algorithm, is used to determine optimal mixtures. The aim of the genetic algorithm is embodied CO2 of concrete, and the performance constraints of the genetic algorithm consist of strength, slump, and chloride penetration durability. The results were as follows: 1) global warming accelerates chloride penetration but has no effect on the results of optimal mixtures. For low-strength concrete free of sustained stress or under low-level compressive stress, strength was the dominant factor for mixture design. However, for low-strength concrete under sustained tensile stress or high-level compressive stress, the durability of concrete under chloride penetration dominated the mixture design. Compared to compressive stress, the
influence of tensile stress on the mixtures was much more apparent; 2) for high-strength concrete, the strength rather than the durability of chloride penetration dominated the mixture design; and 3) the optimal mixtures of concrete for other purposes such as material cost were determined. The optimal mixtures with low cost overlapped with those designed for low CO2 emissions. Summarily, the proposed model provides a general method to design mixtures considering sustainability, strength, slump, and durability of chloride penetration with structural stress and global warming.