城市地下综合管廊接缝PVA纤维混凝土性能试验研究

Experimental study on performance of PVA fiber concrete for joints of urban underground integrated pipe gallery

为改善城市地下综合管廊预制管节接缝混凝土的早期开裂现象、提升混凝土的抗折强度及抗渗性,分别以不同掺量向基准混凝土单独掺入8mm、12mmPVA纤维,通过室内试验进行了PVA纤维混凝土的早期开裂、抗折强度及抗渗试验,并与基准混凝土进行了对比。试验结果表明:掺入8mm、12mmPVA纤维均能有效抑制混凝土早期裂缝的产生,裂缝面积最多可减少89.6%,效果明显;掺入PVA纤维使混凝土抗折强度显著提升,但并非掺量越大,提升效果越好,本试验中最佳掺量为0.9kg/m^3;PVA纤维可有效提升混凝土抗渗性,固定掺量为1.3kg/m^3下,12mmPVA纤维提升效果更好。与基准混凝土相比,PVA纤维混凝土力学性能的改善效果显著,现场实际应用效果良好,材料经济效益明显。因此,PVA纤维混凝土在地下综合管廊工程中具有广阔的应用前景。

In order to improve the early cracking of the joint concrete of the prefabricated pipe joints of urban underground integrated pipe joints,and to improve the flexural strength and impermeability of concrete,8mm and 12mm PVA fibers respectively mixed into the reference concrete with different dosages were passed through the indoor test.The early cracking,flexural strength and impermeability test of PVA fiber concrete were carried out and compared with the reference concrete.Test results show that the incorporation of 8mm and 12mm PVA fibers can effectively inhibit the early cracking of concrete,and the crack area can be reduced by up to 89.6%,with obvious effect.The blending of PVA fiber makes the flexural strength of concrete significantly improved,but the larger the blending amount,the better the lifting effect.The optimum dosage in this test is 0.9 kg/m^3.PVA fiber can effectively improve the impermeability of concrete.The fixed dosage is 1.3 kg/m^3,and the 12 mm PVA fiber has better lifting effect.Compared with the reference concrete,the mechanical properties of PVA fiber concrete have a significant improvement effect,and the actual application effect on the site is good,and the material economic benefits are obvious.Therefore,PVA fiber concrete has broad application prospects in underground integrated pipe gallery engineering.