Fakang Yang , Jianhui Liu , Hengrui Jia , Zheng Chen , Leping Liu , Junmin Zhu , Shanwu Li , Chuanglin Lai , Caijun Shi
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引用次数: 0
Abstract
For promoting the application of alkali-activated slag/metakaolin (AASM) materials in karst areas, it is crucial to understand the corrosion properties of AASM materials in carbonic acid solutions. This paper systematically investigates the evolution of mechanical properties, phase composition, and microstructure of AASM materials in carbonic acid solution environments. The research results indicate that the corrosion mechanism of AASM in carbonic acid solution environments can be summarized as four stages: the dissolution stage, the C-(N)-A-S-H gel decalcification and calcium carbonate formation stage, the further corrosion of calcium carbonate stage, and the slow corrosion stage. Depending on the degree of Ca2+ leaching, the corrosion layers can be divided from the outermost to the innermost layers into the gel layer, the carbonation layer, and the un-corrosion layer. In carbonic acid solution environments, significant leaching of Na+ and OH− occurs in pore solution, which hinders the development of strength. Additionally, the diffusion of CO32− and HCO3− ions dissolved in water into the C-(N)-A-S-H gel, which react with the gel to form calcium carbonate, leads to gel decomposition. Moreover, the generated calcium carbonate is further corrosion into soluble calcium bicarbonate, resulting in substantial leaching of Ca2+, deterioration of pore structure, and increased aggregation degree of C-(N)-A-S-H gel structure. As the MK content increases, the calcium content in the system decreases, leading to a higher crosslinking degree and enhanced resistance of the C-(N)-A-S-H gel to carbonic acid solution corrosion, thereby reducing the corrosion rate of AASM materials. The research results provide new insights into the application of AASM materials in karst areas.
期刊介绍:
Cement & concrete composites focuses on advancements in cement-concrete composite technology and the production, use, and performance of cement-based construction materials. It covers a wide range of materials, including fiber-reinforced composites, polymer composites, ferrocement, and those incorporating special aggregates or waste materials. Major themes include microstructure, material properties, testing, durability, mechanics, modeling, design, fabrication, and practical applications. The journal welcomes papers on structural behavior, field studies, repair and maintenance, serviceability, and sustainability. It aims to enhance understanding, provide a platform for unconventional materials, promote low-cost energy-saving materials, and bridge the gap between materials science, engineering, and construction. Special issues on emerging topics are also published to encourage collaboration between materials scientists, engineers, designers, and fabricators.