界面剂对全轻陶粒混凝土与普通混凝土粘结界面力学性能的影响

Effect of interfacial agents on the mechanical properties of the interface between full lightweight ceramsite concrete and ordinary concrete

制备了5种粘结界面的全轻陶粒混凝土与普通混凝土粘结试件,通过劈裂抗拉、剪切和弯曲等力学试验及SEM测试,探究界面剂对全轻陶粒混凝土与普通混凝土粘结界面力学性能的影响。力学试验结果表明:涂抹界面剂可有效改善界面区结构,大幅提高界面力学性能;环氧树脂界面剂是改善界面劈裂抗拉强度和抗折强度的最优界面剂,强度值分别可提升56.5%和38.3%;聚合物类胶浆界面剂对界面抗剪强度的提升效果最为明显,可提升71.2%;涂抹水泥净浆界面的力学性能也能满足行业标准要求,硅灰水泥净浆作为界面剂较水泥净浆更优;界面剂对力学指标的影响程度从强到弱依次为劈裂抗拉强度、抗折强度和抗剪强度。建立了以全轻陶粒混凝土力学指标为基础、考虑界面剂影响的新老混凝土界面力学强度计算公式。SEM测试从微观层面较好地解释了力学性能测试结论:涂抹界面剂能减小新老混凝土间的微观裂缝宽度,以环氧树脂界面剂和聚合物类胶浆的效果较明显;涂抹界面剂可有效降低界面过渡区的孔隙率,孔隙率下降幅度为46.44%~60.81%。研究结论对混凝土结构加固界面处理具有参考价值。

Five types of full lightweight ceramsite concrete and ordinary concrete composite specimens with different interfacial agents were produced.Moreover,mechanical tests(splitting tensile,shear and bending tests)and SEM tests were performed to investigate the effect of interfacial agents on the mechanical properties of the interface between full lightweight ceramsite concrete and ordinary concrete.The mechanical test results show that firstly,the applying interfacial agent can effectively improve the structure of the interfacial zone and substantially enhance the mechanical properties of the interface.For interfacial splitting tensile strength and flexural strength,epoxy resin is the optimal interfacial agent and the strength values will be increased by 56.5%and 38.3%,respectively.The polymer mortar has the most significant effect on the improvement of interfacial shear strength,which can be improved by 71.2%.The mechanical properties of the interface coated with cement paste can also meet the requirements of industry standards.As an interfacial agent,cement paste containing silica fume is superior to cement mortar.Secondly,the influence degree of interface agent on mechanical indexes from strong to weak is splitting tensile strength,flexural strength and shear strength.Thirdly,based on the mechanical indexes of full lightweight ceramsite concrete,a formula for calculating the mechanical strength of the interface between old and new concrete considering the influence of interfacial agents was established.Finally,SEM testing provides a good explanation of the conclusions of mechanical performance testing at the micro level.The use of interfacial agent can reduce the microcrack width between new and old concrete.Among them,the effect of epoxy resin interfacial agent and polymer mortar is more obvious.Besides,it can effectively reduce the porosity of the interfacial transition zone,with a decrease of 46.44%-60.81%.The research conclusions have reference value for the interface treatment of concrete structure reinforcement.