Luo Jianlin, Chen Shuaichao, Li Qiuyi, Liu Chao, Gao Song, Zhang Jigang, Guo Junbing
School of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China.
Collaborative Innovation Center of Engineering Construction and Safety in Shandong Blue Economic Zone, Qingdao University of Technology, Qingdao 266033, China.
Nanomaterials (Basel). 2019 Mar 1;9(3):325. doi: 10.3390/nano9030325.
There is a constant drive to improve the properties of recycled concrete owing to its inferior strength and fracture toughness compared to normal concrete and recent progress in graphene oxide (GO) nanomaterials impelling nanosized reinforcements to recycled concrete. Here, GO-modified natural sand (NS)- or recycled sand (RS)-based mortars (GONMs or GORMs) with six GO fractions (s) were fabricated to explore their 28 d mechanical strengths (, ), fracture toughness (, ), and microhardness (), as well as their crystal phases (using X-ray powder diffraction) and microstructures (using scanning electronic microscopy). Results reveal, greater enhancements in mechanical strengths (4.50% and 10.61% in , 4.76% and 13.87% in ), fracture toughness (16.49% and 38.17% in , 160.14% and 286.59% in ), and microhardness (21.02% and 52.70% in ) of GORM with just 0.025 wt‰ and 0.05 wt‰ GO, respectively, with respect to the control are achieved when comparing with those of GONM with the same . More zigzag surfaces, more irregular weak interface slips, and the relatively lower strengths of RS bring the superiority of the template and reshaping effects of GO into full play in GORM rather than in GONM. These outcomes benefit a wide range of applications of recycled concrete products.
由于再生混凝土与普通混凝土相比强度和断裂韧性较差，且氧化石墨烯（GO）纳米材料的最新进展推动了纳米级增强材料应用于再生混凝土，因此人们一直在不断努力改善再生混凝土的性能。在此，制备了含有六种GO掺量的GO改性天然砂（NS）或再生砂（RS）基砂浆（GONM或GORM），以探究其28天的力学强度（抗压强度、抗折强度）、断裂韧性、显微硬度，以及它们的晶相（使用X射线粉末衍射）和微观结构（使用扫描电子显微镜）。结果表明，与相同掺量的GONM相比，GORM中仅0.025 wt‰和0.05 wt‰的GO就能分别使抗压强度提高4.50%和10.61%、抗折强度提高4.76%和13.87%、断裂韧性提高16.49%和38.17%、显微硬度提高21.02%和52.70%。更多的锯齿状表面、更多不规则的弱界面滑移以及RS相对较低的强度，使得GO在GORM中比在GONM中更能充分发挥模板和重塑效果的优势。这些成果有利于再生混凝土产品的广泛应用。
