Experimental Investigation On Interface Shear And Tensile Strength Between Old And New Concrete At Different Moisture Condition

This research work is dedicated to experimental investigation on interface shear and tensilernstrength between old and new concrete. Twenty Push-off specimens were cast on thernexperimental program of the shear test. Nine specimens were monolithically cast andrneleven specimens were cast with an interface. The surface of the substrate concrete wasrnleft as cast. The shear specimen was tested by varying confinements i.e. withoutrnconfinement bar, with 100 and 125 initial confining strains. In addition to the abovernparameters, environmental conditions i.e. dry and wet conditions were also considered inrnthis research. rnIt was observed from this experimental program that the presence of an interface betweenrnold and new concrete causes a reduction of shear and tensile strength. For shear specimens,rna reduction in shear strength of 77.39 %, 54.07 % and 38.92% for without confinement,rn100 initial confinement strain, and 125 initial confinements respectively werernobtained. The presence of water also has an adverse effect on the shear strength of concreterna reduction of up to 10% was observed. rnNine specimens were cast on the experimental program for the tensile test. Threernspecimens with interface and dog bone shaped mold were cast and tested using directrntensile test six cylindrical specimens were cast monolithically. This experimental programrnalso indicated the presence of an interface between old and new concrete reduces tensilernstrength by 50%-70%. rnThe roughness of the shear specimen was measured. For monolithically cast surfacernarithmetic mean deviation of the profile, Ra coefficient, was higher and for cast withrninterface sample, Ra was smaller. The roughness was measured for five specimens.rnEvidently, as mean roughness increases shear bond strength also increase. rnA model of the specimen for both shear and tension without an interface was simulated onrna nonlinear finite element analysis program DuCOM-COM3 for monotonic loading. Thernultimate load was captured in fair proximity with the model.

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