Carbonation-load coupling effects can aggravate the inhomogeneity of recycled aggregate concrete (RAC) which contains old attached mortar (OAM) and new added mortar (NAM). In this study, these mortars are first distinguished using an iron oxide. Afterwards, accelerated carbonation coupled with four-point bending effects are applied on the RAC samples, and the carbonation depths in compressive, load-free and tensile zones are compared. The loading rate equals to 40% RAC flexural strength. The microstructures of the mortars in different zones are then compared. Moreover, a computing method for the steel corrosion zone widths of the RACs is proposed after the figures determined using the OAMs and NAMs in different zones as samples are compared. The results show that the carbonation depths of RACs present a significant difference which is more remarkable compared with natural aggregate concrete. Besides, the load shows significant impacts on the mortar microstructure and steel corrosion zone width. Specifically, the effect of tensile stress on OAMs is more obvious than that on NAMs, but there is no such difference in compressive zone. Furthermore, using the OAMs in tensile zone as the samples concludes the highest steel corrosion zone width which is suggested to be used to evaluate the carbonation service life of RAC structures for avoiding the overestimation of structure safety.

碳化负荷耦合效应会加剧再生骨料混凝土（RAC）的不均匀性，后者包含旧的附着砂浆（OAM）和新添加的砂浆（NAM）。在这项研究中，这些砂浆首先使用氧化铁进行区分。然后，将加速碳化和四点弯曲效应结合在一起应用于RAC样品，并比较压缩，无负荷和拉伸区域的碳化深度。加载速率等于40％RAC弯曲强度。然后比较不同区域中灰浆的微观结构。此外，在比较使用不同区域的OAM和NAM确定的数据作为样本后，提出了RACs的钢腐蚀区域宽度的计算方法。结果表明，RACs的碳化深度存在显着差异，与天然骨料混凝土相比，差异更为明显。此外，载荷对砂浆的显微组织和钢腐蚀区的宽度也有显着影响。具体而言，拉伸应力对OAM的影响比对NAM的影响更为明显，但压缩区没有这种差异。此外，使用拉伸区域的OAM作为样本得出最高的钢腐蚀区域宽度，建议将其用于评估RAC结构的碳化寿命，以避免过高估计结构安全性。拉应力对OAM的影响比对NAM的影响更为明显，但压缩区没有这种差异。此外，使用拉伸区域的OAM作为样本得出最高的钢腐蚀区域宽度，建议将其用于评估RAC结构的碳化寿命，以避免过高估计结构安全性。拉应力对OAM的影响比对NAM的影响更为明显，但压缩区没有这种差异。此外，使用拉伸区域的OAM作为样本得出最高的钢腐蚀区域宽度，建议将其用于评估RAC结构的碳化寿命，以避免过高估计结构安全性。