Gao Song, Gong Yaoyao, Li Nan, Ban Shunli, Liu Ang
School of Civil Engineering, Qingdao University of Technology, Qingdao 266011, China.
Collaborative Innovation Center of Engineering Construction and Safety in Shandong Blue Economic Zone, Qingdao Technological University, Qingdao 266033, China.
Materials (Basel). 2021 Aug 31;14(17):4960. doi: 10.3390/ma14174960.
This research focused on the modification effects on recycled concrete (RC) prepared with nano-SiO and CO cured recycled coarse aggregates (RCA) subjected to an aggressive ions environment. For this purpose, RCA was first simply crushed and modified by nano-SiO and CO respectively, and the compressive strength, ions permeability as well as the macro properties and features of the interface transition zone (ITZ) of RC were investigated after soaking in 3.5% NaCl solution and 5% NaSO solution for 30 days, respectively. The results show that nano-SiO modified RC displays higher compressive strength and ions penetration resistance than that treated by carbonation. Besides, we find that ions attack has a significant influence on the microcracks width and micro-hardness of the ITZ between old aggregate and old mortar. The surface topography, elemental distribution and micro-hardness demonstrate that nano-SiO curing can significantly decrease the microcracks width as well as Cl and SO penetration in ITZ, thus increasing the micro-hardness, compared with CO treatment.
本研究聚焦于在侵蚀性离子环境下，纳米二氧化硅（nano-SiO₂）和二氧化碳（CO₂）养护再生粗集料（RCA）制备的再生混凝土（RC）的改性效果。为此，首先对RCA进行简单破碎，然后分别用纳米二氧化硅和二氧化碳进行改性，并分别在3.5%氯化钠（NaCl）溶液和5%硫酸钠（Na₂SO₄）溶液中浸泡30天后，研究了RC的抗压强度、离子渗透性以及界面过渡区（ITZ）的宏观性能和特征。结果表明，纳米二氧化硅改性的RC比碳化处理的RC具有更高的抗压强度和抗离子渗透性。此外，我们发现离子侵蚀对旧集料与旧砂浆之间ITZ的微裂纹宽度和显微硬度有显著影响。表面形貌、元素分布和显微硬度表明，与二氧化碳处理相比，纳米二氧化硅养护可显著减小ITZ的微裂纹宽度以及氯离子（Cl⁻）和硫酸根离子（SO₄²⁻）的渗透，从而提高显微硬度。
