纤维增韧地聚物混凝土力学性能与微观结构

Mechanical properties and microstructure of fiber reinforced geopolymer concrete

为改善地聚物延性较差的缺点,采用镀铜微细钢纤维与聚丙烯纤维制备了不同纤维类型、布置形式与体积掺量的纤维增韧粉煤灰-矿渣基地聚物混凝土,对其力学性能进行了试验研究,并通过扫描电子显微镜从微观层面解释了不同布置形式的纤维增韧机理。结果表明:钢纤维与聚丙烯纤维分别以拔出与断裂的形式有效地阻止地聚物混凝土裂缝的发展;对于整体式单掺钢纤维与整体式混掺纤维地聚物混凝土试样,其劈裂抗拉强度与抗折强度均得到显著提升;层布式钢纤维地聚物混凝土试样可达到与整体式纤维地聚物混凝土相当的力学性能且前者的纤维用量仅为后者的40%左右;与整体式纤维增韧机理不同,层布式钢纤维地聚物混凝土试样中双层钢纤维相当于“双层弹性板”,除了聚丙烯纤维以及钢纤维的“桥接”作用,还可与基体周围的钢纤维互相交叉形成网状结构,钢纤维网状结构之间的相互作用限制了纤维的相对位移,显著提升了试样的力学性能。

To improve the poor ductility of geopolymer,fiber reinforced fly ash-slag geopolymer concrete with different fiber types,arrangement forms and volume content was prepared by using copper coated micro steel fiber and polypropylene fiber.The mechanical properties of geopolymer concrete were studied,and the fiber reinforcement mechanism with different arrangement forms was further explained based on scanning electron microscope.The results show that steel fiber and polypropylene fiber can effectively prevent the development of cracks in geopolymer concrete in the form of pull-out and fracture,respectively.The splitting tensile and flexural strength of non-layered reinforced geopolymer concrete samples with single steel fiber and hybrid fiber are significantly improved.The mechanical properties of layered fiber reinforced geopolymer concrete are equivalent to that of non-layered fiber reinforced geopolymer concrete,and the fiber content of the former is only about 40%of that of the latter.Different from the non-layered fiber reinforced mechanism,the double-layer steel fiber in the layered fiber reinforced geopolymer concrete is equivalent to the“double-layer elastic plate”.Besides the“bridging”effect of polypropylene fiber and steel fiber,it also intersects with the steel fiber around the matrix to form a network structure.The interaction between the steel fiber network structure limits the relative displacement of the fiber and significantly improves the mechanical properties of the sample.