粗合成纤维长径比对喷射混凝土性能的影响  

Influence of aspect ratio of macro synthetic fiber on properties of shotcrete

作　　者：苏安双[1] 曾雄辉[2] 丁建彤[1] 宁逢伟[1] 蔡跃波[1] 

机构地区：[1]南京水利科学研究院,江苏南京210024 [2]二滩水电开发有限责任公司,四川成都610051

出　　处：《混凝土》2013年第4期67-72,76,共7页Concrete

摘　　要：粗合成纤维对喷射混凝土的增韧效果与钢纤维相比有明显差距。为了改善粗合成纤维的增韧效果,采用小型湿喷成型试件,测试当量直径为0.5～1.0 mm、断面形状分别为8字形或椭圆形的2种聚丙烯粗合成纤维的长径比对C30湿喷混凝土工作性、纤维分散性、回弹率、抗压强度、抗拉强度、抗折强度及弯曲韧性的影响。纤维长径比为30～76,长度为24～50 mm,掺量为8 kg/m3。结果表明:整体上,随纤维长径比增加,抗压、抗拉、抗折强度及弯曲韧性先增加后降低。对所用的2种纤维,长径比约为50时对喷射混凝土增强、增韧作用最为明显。适宜长径比范围内,长径比增大使边壁效应减弱,基体对纤维咬合作用增强,利于提高喷射混凝土力学性能;长径比过大时,纤维分布不均及结团减弱了纤维增强、增韧作用。Sharp difference existed between toughening effect of macro synthetic fiber and steel fiber.In order to improve the toughening effect of macro synthetic fiber,the influence of two sorts of macro polypropylene fibers with equivalent diameter of 0.5-1.0 mm and ‘ 8＇-shape and elliptic section on the workability, fiber dispersibility, rebotmd ratio, compressive strength, flexural strength and toughness of C30 fiber reinforced shotcrete were investigated through small scale spaying experiment.The dosage of mentioned fibers with aspect ratio of 30-76 and length of 24-50 mm in shotcrete was 8 kg/m3.The results indicated that the compressive strength, tensile strength, flexural strength and toughness exhibited increasing tendency first and then decreased with the increase of aspect ratio generally.For the two sorts of fibers adopted, the fiber with aspect ratio of 50 presented the most significant strengthening and toughening effect.With aspect ratio in appropriate range, the increase of aspect ratio led to the reduction of boundary effect and enhance of meshing effect between matrix and fibers, which was beneficial to the improvement of the mechanical properties of shotcrete.While the aspect ratio was too high, the heterogeneous distri- bution and clustering of fibers weakened the strengthening and toughening effect.

关 键 词：粗合成纤维 长径比 喷射混凝土 力学性能 弯曲韧性 

分 类 号：TU528.041[建筑科学—建筑技术科学]