新旧混凝土界面粘结(国外英文资料).docVIP

新旧混凝土界面粘结(国外英文资料) After hardening, a good mechanical occlusion is formed. For the binding under the oblique and underside, due to the exudation in concrete, air bubbles trapped in the bottom of the old concrete, coupled with the shrinkage of concrete itself, congenital micro cracks formation, formation of weak links, greatly reduces the bond strength of new and old concrete, below inclined top and top surface bond strength. ????? ?? A)??? ?? B)?????? (c)????? ? (d)????????? (e) (a) on the repair; (b) under repair; (c) the side complement (d) is reclined; (e) to make up; N -- repairing concrete; O -- old concrete Figure 1 interface orientation diagram ????? (2) pre-wetting of old concrete surfaces ????? In advance of the old concrete surface wetting is a method that is widely used in the project but some research suggests the existence of water film will affect the good bond between new and old concrete. Actually it according to the circumstances of interface agent, some interface agent under the condition of the residual water interface will seriously affect the cohesive force, some interface agent can compatible with water and dry wet state on bonding strength. ????? (3) the thickness of the interface ????? In general, the thickness of the interface layer increases, the tensile and shear strength decreases, and the interface agent has a suitable thickness problem. The maximum brush thickness of an interfacial agent should not exceed 3mm, preferably with 0.5 mm - 2.5 mm. In addition, the polymer class above a certain temperature under sustained load interface agent, binder and generate creep and failure, and reduce the interface layer thickness changes creep, at the same time, due to different coefficient of thermal expansion and shrinkage internal stress also can be reduced by reducing interfacial layer thickness, thus improving the interface stress state. ????? (4) age ????? In general, a large part of cement hydration in 28 days basically completed, but the acti