Chen Chunhong, Wang Lei, Liu Ronggui, Yu Jiang, Liu Hui, Wu Jinlong
School of Urban Construction, Changzhou University, 21 Gehu Middle Road, Wujin District, Changzhou 213164, China.
Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang 212013, China.
Materials (Basel). 2023 Feb 3;16(3):1306. doi: 10.3390/ma16031306.
Recycled fine aggregate (RFA) produced from concrete waste is commonly used in the construction industry; however, its use for structural concrete members has not been extensively studied. Moreover, its durability in a drying-wetting cycle environment still needs to be examined. In this study, the intrusion process of chloride in concrete under the drying-wetting cycles is experimentally characterized. Chloride penetration tests are carried out on concrete with the incorporation of different RFA replacement rates and mineral admixtures (i.e., fly ash and silica fume). The results show that the chloride penetration of recycled fine aggregate concrete (RFAC) is dependent upon the performance of the concrete itself, while the deterioration of chloride ion erosion resistance is due to the combined action of the replacement rate of RFA and the drying-wetting cycles. The incorporation of RFA degrades the properties of RFAC owing to its drawbacks in the degradation of interfacial properties of RFAC. Exposure to the drying-wetting cycle environment causes the content of free chloride ions in RFAC to increase initially before decreasing with the erosion depth, thereby showing an obvious convection zone and diffusion zone. The incorporation of the mineral admixture can effectively improve the compactness of the concrete microstructure and make concrete less susceptible to chloride ions ingress. RFAC mixed with 15% fly ash and 10% silica fume has a comparable resistance to chloride penetration as a natural aggregate concrete, which is a feasible method for the application of RFA.
由混凝土废料生产的再生细骨料（RFA）在建筑行业中普遍使用；然而，其在结构混凝土构件中的应用尚未得到广泛研究。此外，其在干湿循环环境中的耐久性仍有待考察。在本研究中，对干湿循环作用下混凝土中氯离子的侵入过程进行了试验表征。对掺入不同RFA替代率和矿物掺合料（即粉煤灰和硅灰）的混凝土进行了氯离子渗透试验。结果表明，再生细骨料混凝土（RFAC）的氯离子渗透取决于混凝土本身的性能，而抗氯离子侵蚀性能的劣化是由于RFA替代率和干湿循环的共同作用。由于RFA在RFAC界面性能劣化方面的缺点，其掺入降低了RFAC的性能。暴露于干湿循环环境中，RFAC中游离氯离子含量最初会增加，随后随侵蚀深度而降低，从而呈现出明显的对流区和扩散区。矿物掺合料的掺入可有效提高混凝土微观结构的致密性，使混凝土更不易受到氯离子侵入。掺入15%粉煤灰和10%硅灰的RFAC具有与天然骨料混凝土相当的抗氯离子渗透能力，这是RFA应用的一种可行方法。
