集料-水泥石界面对混凝土损伤断裂性能的影响

通过不同的界面处理工艺改变混凝土中集料-水泥石粘结强度,研究集料-水泥石界面对混凝土单轴受压应力-应变全曲线、四点弯曲断裂能和裂缝扩展模式的影响规律.研究表明:集料-水泥石界面对混凝土的强度和韧性具有一定的影响,强化集料-水泥石界面可以提高混凝土的抗压强度,但却降低其韧性;弱化粗集料-水泥石界面,会明显降低混凝土的强度和变形能力;而弱化细集料-水泥石界面能提高混凝土的断裂能和延性指数,原因是细集料表面的初始缺陷将宏观分离裂缝诱导为均匀分布于砂浆基体中的弥散裂缝,增加了有效裂缝长度,同时也增大了断裂过程区,从而改善了混凝土的延性.

Effect of Aggregate-Cement Paste Interface on Damage and Fracture of Concrete

The interfacial bond strength between aggregate and cement paste was changed by using different interface-treating technology for researching the effect of aggregate-cement paste interface on the stress-strain curve,fracture energy and crack propagation model of concrete.The study shows that enhancing the aggregate-cement paste interface can increase the compressive strength but decrease the toughness of concrete.Weakening the rough aggregate-cement paste interface can increase the strength with decreasing the tougthness of concrete at the same time.However,weakening the fine aggregate-cement paste interface can increase the fracture energy of concrete,the reason of which is that the initial imperfection in concrete induces the macro discrete crack into smeared crack that dispersed in the mortar,which can increase the effective crack length and the fracture process zone,so the deformation performance of concrete was improved obviously.