灌浆料与既有混凝土界面黏结性能试验研究

Experimental study on interfacial bonding performance between existing concrete and grout

为确保灌浆料和既有混凝土结构共同工作,通过直接剪切试验,研究了灌浆料和普通混凝土之间的界面黏结强度。考虑连接界面形状、灌浆料强度与龄期等因素设计制作了18组54个Z型直剪试件,通过剪切试验测量了应变及位移,得到了相应的界面黏结-滑移曲线,提出了灌浆料修复既有混凝土结构的界面黏结滑移模型,并给出了界面黏结刚度建议值。试验结果表明:界面形状为三角形时的界面黏结强度最大,梯形的次之,光滑的最小;灌浆料强度对界面黏结强度的影响与灌浆料龄期密切相关,7d龄期时界面黏结强度随灌浆料强度的增加而减小,28d龄期时界面黏结强度随灌浆料强度的增加而增大;灌浆料与混凝土的界面黏结强度随灌浆料龄期的增加而增大,灌浆料龄期对光滑界面的影响程度最大,对梯形以及三角形界面的影响程度较小。

In order to ensure that the grouting material layer and existing concrete work together,the interfacial bond strength between grouting material and normal concrete substrate was experimentally investigated by conducting direct shear tests.Considering factors such as the connection interface form,the strength and age of the grout,a total of 18 groups of 54 Z-shaped direct shear specimens were designed and made in this study.Direct shear tests were conducted to measure strain and displacement,and the corresponding interfacial bond-slip curves were obtained.A bond-slip model for the interface between the grout and the existing concrete was proposed,and a certain value of interfacial bond stiffness was suggested.Results showed that for composite specimens,the interfacial bond strength was the highest for the triangular interface form,followed by the trapezoidal interface and smooth interface,which had the lowest.The effect of grout strength on the interfacial bond strength was closely related to the age of the grout.The interfacial bond strength decreased as the increase of grout strength at the age of 7 days and increased as the increase of grout strength at the age of 28 days.The interfacial bond strength between grout and concrete increased with the age of grout,and the age of the grout had the greatest influence on the smooth interface,and less on the trapezoidal and triangular interfaces.