Ho Ha Vinh, Choi Eunsoo, Kim Duhyeon, Kang Joowon
Department of Civil Engineering, Hongik University, Seoul 04066, Korea.
School of Architecture, Yeungnam University, Gyeongbuk 38541, Korea.
Materials (Basel). 2021 Mar 20;14(6):1522. doi: 10.3390/ma14061522.
The straining behavior of the shape memory alloy (SMA) fibers-reinforced mortar was investigated in this study by the monotonic compressive and cyclic compressive tests. Two types of SMA fibers with a crimped and dog-bone shape were used due to the high pullout resistance capacity, which guaranteed that the fibers and mortar matrix were composited well. The plain mortar was mixed with two different compositions to create the higher elastic modulus mortar matrix and the lower elastic modulus mortar matrix compared with the elastic modulus of SMA fibers. The results of the experimental test indicated that the non-heated SMA fibers could control the strains in both elastic and plastic phases; in which, the crimped fiber was more effective in precracking due to the higher composite capacity while the dog-bone-shaped fiber had a higher effect in post-cracking. After heating, the dog-bone-shaped fiber slipped more than that of the crimped fiber; thus, the heated crimped fiber was more effective than the heated dog-bone-shaped fiber in controlling strains after cracking. The effect of SMA fibers on the elastic modulus depended on both the elastic modulus of mortar matrix and the property of SMA fibers. In the plastic phase, the fibers were effective on reducing the speed of damage in monotonic case. An equation using reinforcing index was suggested for damage evolution in the cyclic case.
本研究通过单调压缩试验和循环压缩试验，对形状记忆合金（SMA）纤维增强砂浆的受力行为进行了研究。由于具有较高的抗拔出能力，使用了两种具有卷曲和狗骨形状的SMA纤维，这确保了纤维与砂浆基体能够良好复合。将素砂浆与两种不同的成分混合，以制备出与SMA纤维弹性模量相比，具有较高弹性模量的砂浆基体和较低弹性模量的砂浆基体。试验结果表明，未加热的SMA纤维在弹性和塑性阶段均能控制应变；其中，卷曲纤维由于具有较高的复合能力，在开裂前更为有效，而狗骨形纤维在开裂后效果更佳。加热后，狗骨形纤维的滑移比卷曲纤维更多；因此，加热后的卷曲纤维在开裂后控制应变方面比加热后的狗骨形纤维更有效。SMA纤维对弹性模量的影响取决于砂浆基体的弹性模量和SMA纤维的性能。在塑性阶段，纤维在单调加载情况下对降低损伤速度有效。针对循环加载情况下的损伤演化，提出了一个使用增强指数的方程。
