PVA纤维水泥基复合材料抗冲蚀磨损性能试验研究

挟沙水流对桥墩的冲蚀磨损严重，继而影响桥梁的安全服役.为此，采用自主研制的冲蚀磨损试验装置，对一种桥墩抗冲蚀磨损材料——聚乙烯醇（polyvinyl alcohol,PVA）纤维水泥基复合材料进行冲蚀磨损试验.以普通砂浆为参照，首先，测试了普通砂浆试块和PVA纤维水泥基复合材料试块的抗压强度；然后，测量了冲蚀引起的质量损失，并分析了两类材料在不同冲击角度下的冲蚀磨损特点；最后，采用计算流体力学程序开展数值模拟，从流场角度对冲蚀磨损机理开展了深入分析.研究结果表明：水胶比对材料抗冲蚀磨损性能影响最大，水胶比越低，材料的强度越高和抗冲蚀磨损性能越好；在不同的冲击角度下，试块表面的冲蚀坑形状不同，在90°冲击条件下，冲蚀坑呈圆环状，在30°冲击条件下，冲蚀坑呈马蹄形；普通砂浆和E3配合比试块随冲击时间增加，单位时间（5 min）的质量损失逐渐减小，但两者的冲蚀过程不同.

Experimental Study on Hydro-Abrasion Performance of Polyvinyl Alcohol Fiber Cementitious Composites

Bridge safety during service is greatly influenced by hydro-abrasion caused by waterborne sand. An independently developed testing device was employed to conduct hydro-abrasion tests on a type of anti-abrasion material, i.e., polyvinyl alcohol (PVA) fiber reinforced cement based composites. Ordinary mortar was selected as the reference material. Firstly, the compressive strengths of the two types of materials were tested and then the weight losses caused by hydro-abrasion were measured. The hydro-abrasion characteristics of the two materials under different impacting angles were analyzed. Finally, the computational fluid dynamics program was used to conduct numerical simulation and the generation mechanisms of abrasion pits were explored on the basis of flow field analysis. Results show that water-binder ratio has the most influence on the anti-abrasion performance; the smaller the water-binder ratio, the larger the material compressive strength and the better the anti-abrasion performance. Abrasion pits on the specimen surfaces have different shapes when suffering impacting of different angles, i.e., the abrasion pit is circular when the impacting angle is 90°, and it is in horseshoe shape when the impacting angle is 30°. The abrasion weight loss of the ordinary mortar specimen and the E3 mix-proportion specimen increases with impacting time. However, the abrasion weight per unit time (5 minutes) of the two types of materials deceases with the increase of the unit time, and their abrasion processes are different.