混杂纤维混凝土与既有混凝土的粘结斜剪性能试验研究

Experimental Research on the Bonding Oblique Shear Performance of HFRC and Existing Concrete

目的研究混杂纤维及涂抹环氧界面剂对新老混凝土粘结性能的影响。方法对12组混杂纤维混凝土(体积分数为0.11%的聚丙烯纤维,体积分数分别为0.8%和1.2%的多锚点钢纤维)与既有混凝土粘结试件(100 mm×100 mm×300 mm)进行斜剪性能试验,并对粘结界面取样进行SEM扫描分析。研究不同纤维掺量及界面剂对新老混凝土的界面粘结强度、破坏形式的影响以及混杂纤维在粘结面的作用机理。结果与普通混凝土试件的粘结斜剪强度相比,1.2HFRC粘结斜剪试件强度提高幅度最大,达到了29%;混杂纤维混凝土试件与单掺钢纤维混凝土试件的粘结斜剪强度差异较小,二者平均提升幅度约为5%,纤维掺量每增加0.1%,斜剪强度平均提升约0.18 MPa;不同纤维掺量的混凝土试件在涂抹环氧界面剂后增幅平均为3 MPa左右。结论混杂纤维掺入后能有效改善粘结界面区的孔隙结构,提高界面粘结性能。

In order to study the effect of hybrid fiber and epoxy interfacial agent on the bonding performance of new and old concrete,the oblique shear performance of 12 groups of hybrid fiber concrete(polypropylene fiber with volume fraction of 0.11%,multi anchor steel fiber with volume fraction of 0.8%and 1.2%)and existing concrete bond specimens(100 mm×100 mm×300 mm)were tested,SEM scanning was carried out for the adhesive interface samples.The influence of different fiber content and interfacial agent on the interface bond strength and failure mode of new and old concrete and the action mechanism of the hybrid fiber on the bonding surface are studied.The research results show that:compared with the bonded oblique shear strength of ordinary concrete specimens,the strength of 1.2HFRC bonded oblique shear specimens is increased by the largest 29%;there is little difference in bond oblique shear strength between hybrid fiber concrete specimens and steel fiber reinforced concrete specimens,with an average increase of about 5%.For every 0.1%increase in fiber content,the average increase in oblique shear strength is about 0.18 MPa;the average increase rate of concrete specimens with different fiber content after applying epoxy interfacial agent is about 3 MPa;the pore structure of interfacial region can be improved and improve the interface bonding performance by the incorporation of hybrid fibers.