凿毛植筋新老混凝土结合面抗剪性能试验研究

Experimental Study on Shear Behavior of New and Existing Concrete Interface with Chiseled and Embedded Reinforcement

新老混凝土结合面是结构整体受力,尤其是剪切受力的关键。以植筋率(0.17%、0.34%、0.51%)和植入钢筋深度(10、15 cm)为变量,制作5组10个Z形试件进行剪切试验,分析植筋率和植入钢筋深度对新老混凝土试件剪切性能的影响规律。结果表明:植筋及整体浇筑试件的破坏面上均伴有骨料剪断和砂浆-骨料脱黏现象,呈典型的脆性破坏特征;植筋试件开裂后,抗剪承载力主要由结合面植入钢筋承担;增加植筋率及植筋深度,试件抗裂性能及抗剪强度均有所提高;整体浇筑试件的开裂、极限剪应力分别为2.98、7.22 MPa,是所有试件的最大值,表明整体浇筑试件的抗裂性能最优,抗剪强度最高。

The interface between the new and existing concrete is the key to the overall structural strength,especially the shear strength.Taking the rebar planting rate(0.17%,0.34%,0.51%)and the depth of post-installed rebar(10,15 cm)as variables,5 groups of 10 Z-shape specimens were fabricated for the shear test,and the influences of the above variables on the specimens’shear behavior were obtained.The results show that the failure surfaces of all specimens are accompanied by aggregate shearing and mortar-aggregate debonding phenomena,exhibiting typical brittle damage characteristics.After cracking of the post-installed rebar specimens,the shear capacity is mainly borne by the post-installed rebar.The crack resistance and shear strength of the specimens are increased by increasing the rebar planting rate and depth of post-installed rebar.The cracking and ultimate shear stresses of the monolithic specimens are 2.98,7.22 MPa respectively,which are the maximum values of all specimens,indicating that the monolithic specimens have the best cracking resistance and the highest shear strength.