Optimal Mixture Design of Low-CO 2 High-Volume Slag Concrete Considering Climate Change and CO 2 Uptake

摘要

High-volume slag (HVS) can reduce the CO~(2)emissions of concrete, but increase the carbonation depth of concrete. In particular, because of the effects of climate change, carbonation will accelerate. However, the uptake of CO~(2)as a result of carbonation can mitigate the harm of CO~(2)emissions. This study proposes an optimal mixture design method of low-CO~(2)HVS concrete considering climate change, carbonation, and CO~(2)uptake. Firstly, net CO~(2)emissions are calculated by subtracting the CO~(2)emitted by the material from the uptake of CO~(2)by carbonation. The strength and depth of carbonation are evaluated by a comprehensive model based on hydration. Secondly, a genetic algorithm (GA) is used to find the optimal mixture. The objective function of the GA is net CO~(2)emissions. The constraints of the GA include the strength, carbonation, workability, and range of concrete components. Thirdly, the results show that carbonation durability is a control factor of the mixture design of low-strength HVS concrete, while strength is a control factor of the mixture design of high-strength HVS concrete. After considering climate change, the threshold of strength control increases. With the increase of strength, the net CO~(2)emissions increase, while the CO~(2)uptake ratio decreases.