不同掺合料对MPC/混凝土抗剪强度的影响

The Influence of Different Admixtures on the Shear Strength of MPC/Concrete

为寻求应用于不同强度等级混凝土最佳粘结抗剪强度的MPC配比,采用双面剪切试验,掺入粉煤灰(5%、10%)、硅灰(0%、5%、10%)到MPC中,对MPC/混凝土(C20、C25、C30、C35、C40)粘结抗剪性能进行研究,得到了MPC与混凝土粘结界面的破坏形式和抗剪强度。结果表明:MPC/混凝土的界面粘结破坏存在混凝土内部破坏、胶体内部破坏和胶体与混凝土剥离破坏三种形式。MPC/混凝土的界面破坏层随着混凝土等级提高由混凝土深层向表层转移。粘结抗剪强度随混凝土等级提高而增加,C40混凝土粘结抗剪强度最高达到2.9 MPa。掺合料中粉煤灰和硅灰为5%的MPC和各强度混凝土的破坏模式较为均衡,界面粘结性能最佳。

In order to seek the optimal MPC(magnesium phosphate cement)mix proportions for bonding shear strength applicable to different grades of concrete,a double-shear test method was employed,in which involved incorporating fly ash(5%,10%)and silica fume(0%,5%,10%)into the MPC.The study examined the bonding shear performance of MPC/concrete(C20,C25,C30,C35,C40)and identified the failure modes and shear strengths at the MPC/concrete bonding interface.The results indicated that there were three forms of interface failure for MPC/concrete bonding:internal failure within the concrete,internal failure within the adhesive,and delamination between the adhesive and concrete.As the grade of concrete increased,the depth of the interface failure layer shifted from deeper layers towards the surface.The bonding shear strength increased with the grade of concrete,reaching up to 2.9MPa for C40concrete.The failure patterns were more balanced and exhibited optimal interface bonding performance when the MPC contained 5%fly ash and silica fume across various concrete strength levels.