氯盐对再生混凝土碳化特性的影响研究

Study of the Effect of Chloride Salts on Carbonation Characteristics of Recycled Aggregate Concrete

摘要: 近年来，再生混凝土作为一种环保、资源节约的建筑材料，受到越来越多的关注和应用。然而，再生混凝土的碳化现象一直是制约其应用的关键问题之一。目前，对再生混凝土碳化的研究主要集中在碳化速率、碳化深度等方面。氯离子是混凝土中常见的一种有害离子，也会影响混凝土的碳化情况。特别是在海岸地区和盐湖地区等环境中，氯离子的浓度较高，会对混凝土结构的稳定性产生较大影响。再生混凝土结构遭受内部和外部氯离子侵蚀，同时还有碳化的影响，这些因素共同作用下大大降低了再生混凝土的耐久性。本实验通过对不同再生粗骨料取代率的混凝土内掺入氯盐，测试不同浓度的氯盐对其快速碳化试验的影响，并记录7 d、14 d和28 d的碳化深度。研究发现，随着碳化时间的增加，碳化深度也增加；再生粗骨料取代率的增加导致碳化深度增加；再生混凝土内部的氯盐减缓了碳化速率和碳化深度；氯盐浓度的增加也会对再生混凝土的碳化深度产生不同程度的影响。

Abstract: In recent years, recycled concrete, as an environmentally friendly and resource-saving construction material, has received more and more attention and application. However, the carbonation phenomenon of recycled concrete has been one of the key problems restricting its application. At present, the research on carbonation of recycled concrete mainly focuses on carbonation rate and carbonation depth. Chloride ion is a common harmful ion in concrete, which also affects the carbonation of concrete. Especially in environments such as coastal areas and salt lake areas, the concentration of chloride ions is high, which can have a greater impact on the stability of concrete structures. Recycled concrete structures are subjected to internal and external chloride ion attack, along with the effects of carbonation, and these factors together greatly reduce the durability of recycled concrete. In this experiment, the effect of different concentrations of chloride salts on the rapid carbonation test was tested by incorporating chloride salts within concrete with different recycled coarse aggregate substitution rates, and the depth of carbonation was recorded at 7, 14 and 28 days. It was found that the carbonation depth increased with the increase of carbonation time; the increase of recycled coarse aggregate substitution rate led to the increase of carbonation depth; the chloride salt inside the recycled concrete significantly slowed down its carbonation rate and carbonation depth; the increase of chloride concentration will also have different degrees of influence on the carbonization depth of recycled concrete.