Experimental Study On Inspection Of Merchandise Concrete Strength By Pull-out Method

With the growing engineering structural complexity and the commercialization development of concrete, concrete admixture and high-strength concrete are now universally used in practical engineering. The component and construction technique have tremendous changed since before, and the dependency relation between physical quantity and the concrete compressive strength has varied. The study of the embedded insert pullout and the post-insert pullout is of important practical significance。The merchandise concrete supplied by one merchandise concrete mixer in Harbin is used in the experiment, the simples of C15, C20, C30, C35, C40, C45 of HSC are made, and there are 72 test cubes (300mm×300mm×300mm) in total. Use"Test method of mechanical properties on ordinary concrete","Technical specification for inspection of concrete compressive strength by rebound method","Technical specification for inspection of concrete compressive strength by pull-out post-install method"as the basis, the following researches are carried out:1. The methods of rebound,post-insert pullout and embedded insert pullout are applied to the 72 test cubes, in this way ,valuable data are got. and the test phenomenon are analyzed.2. Based on analysis, collation, calculation to the testing data of pullout force, the concrete strength conversion calculation formulas are established, its related coefficients and relative standard can meet the requirement, It showed good correlation between the data of pullout force and cube strength, the concrete strength conversion curve by embedded insert pullout and post-insert pullout method in Heilongjiang Province are setup, and as a reference to national concrete strength conversion curve.3. The concrete strength conversion calculation formulas by rebound method is also established, and its related coefficients and relative standard can meet the requirement, it is might be an important basis for establishing local and national curves to ascertain concrete strengths of structures by rebound method.4. The concrete failure mechanism of expanding bolt pullout method is analyzed, and the influence of the pullout and rebound method is summarized in the paper.5. The modified Mohr-Coulomb failure theory is used, on the base of curving failure surface, the concrete strength conversion calculation formula is derived: f_c= 2.3P;Finite Element Method analysis on the post-insert pullout method is performed by using of ANSYS software. The failure mechanism of post-insert pullout is summarized in the paper. That is, the concrete failure in the pullout tests is mainly tension failure.