短切玄武岩纤维对混凝土的增强效果及机理

REINFORCING EFFECT AND MECHANISM OF CHOPPED BASALT FIBER ON CONCRETE

混凝土具有抗压强度高,抗拉强度低的特点,玄武岩纤维的掺入能够显著提高其抗拉强度,提高混凝土的综合力学性能。通过改变纤维的种类、长度、掺量,对比纤维混凝土与素混凝土的各项力学性能。试验结果表明：20 mm长（长径比为1 538.46）、掺量为3 kg/m3的玄武岩纤维掺入时,与素混凝土相比,抗压、抗拉、抗折性能分别增加了33%、23%、40%,具有显著的增强效果;随着纤维长度与掺量的增加,纤维混凝土力学性能下降,当玄武岩纤维掺量为12 kg/m3时,抗压强度增加了5%,抗拉和抗折强度降低了4%和8%。扫描电子显微镜扫描结果表明：玄武岩纤维的掺入能够降低混凝土孔隙率和初始裂隙;同时玄武岩纤维能够传递荷载,使应力均匀分布,控制裂隙发育。玄武岩纤维能够显著增强混凝土的抗拉强度,具有良好的效果。通过对玄武岩纤维掺量的控制,可以最大程度地改善混凝土的力学性能。

Concrete is characterized with high compressive strength and low tensile strength. By adding basalt fiber（BF）,concrete＇s tensile strength and comprehensive mechanical properties could be significantly improved. Based on the changes of the type,length and content of BF,the mechanical properties of fiber concrete and plain concrete were compared. The results indicated that when the length reached 20 mm（which length to diameter ratio of basalt was1 538. 46） and the content was 3 kg/m3,it had a remarkable enhancement effect,the compressive strength,tensile strength and flexural strength of the concrete could be increased by 33%,23%,and 40% respectively. With the increase of the fiber＇s length and content,the mechanical properties of fiber concrete decreased. When the length was20 mm,the content was 12 kg/m3,the concrete＇s compressive strength increased by 5%,while its tensile strength and the flexural strength decreased by 4% and 8% respectively. The result of SEM showed that when it was added to concrete,the BF could reduce the porosity of concrete and the initial cracks. In addition,by transferring loads,the BF fiber could make the stress distribute uniformly and control the development of fracture. The BF exhibited a significantly reinforcing effects on the tensile strength of the concrete,and the mechanical properties of concrete could be improved by BF.