Ying Jingwei, Han Zewen, Shen Luming, Li Wengui
College of Civil Engineering and Architecture, Guangxi University, Nanning 530004, China.
School of Civil Engineering, The University of Sydney, NSW 2006, Australia.
Materials (Basel). 2020 Oct 16;13(20):4631. doi: 10.3390/ma13204631.
Parent concrete coming from a wide range of sources can result in considerable differences in the properties of recycled coarse aggregate (RCA). In this study, the RCAs were obtained by crushing the parent concrete with water-to-cement ratios () of 0.4, 0.5 and 0.6, respectively, and were strengthened by carbonation and nano-silica slurry wrapping methods. It was found that when was 0.3, 0.4 and 0.5, respectively, compared with the mortar in the untreated RCA, the capillary porosity of the mortar in the carbonated RCA decreased by 19%, 16% and 30%, respectively; the compressive strength of concrete containing the carbonated RCA increased by 13%, 11% and 13%, respectively; the chloride diffusion coefficient of RAC () containing the nano-SiO slurry-treated RCA decreased by 17%, 16% and 11%; and that of RAC containing the carbonated RCA decreased by 21%, 25% and 26%, respectively. Regardless of being strengthened or not, both and porosity of old mortar in RCAs increased with increasing . For different types of RCAs, increased obviously with increasing water absorption of RCA. Finally, a theoretical model of considering the water absorption of RCA was established and verified by experiments, which can be used to predict the under the influence of different factors, especially the water absorption of RCA.
来源广泛的母体混凝土会导致再生粗骨料（RCA）的性能存在显著差异。在本研究中，通过分别破碎水灰比（）为0.4、0.5和0.6的母体混凝土获得再生粗骨料，并采用碳化和纳米二氧化硅浆液包裹法对其进行增强。研究发现，当分别为0.3、0.4和0.5时，与未处理再生粗骨料中的砂浆相比，碳化再生粗骨料中砂浆的毛细孔隙率分别降低了19%、16%和30%；含有碳化再生粗骨料的混凝土抗压强度分别提高了13%、11%和13%；含有纳米SiO浆液处理再生粗骨料的再生骨料混凝土（RAC）的氯离子扩散系数降低了17%、16%和11%；含有碳化再生粗骨料的RAC的氯离子扩散系数分别降低了21%、25%和26%。无论是否增强，再生粗骨料中旧砂浆的和孔隙率均随的增加而增加。对于不同类型的再生粗骨料，随再生粗骨料吸水率的增加而明显增加。最后，建立了考虑再生粗骨料吸水率的理论模型，并通过实验进行了验证，该模型可用于预测不同因素影响下的，尤其是再生粗骨料吸水率影响下的。
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