Resesrch On High Strength Concrete Strength Survey Based On Rebound Method In Hebei

In recent years, with the rapid development of civil engineering in our country,which high-rise buildings, large span bridge construction is increasing, the application of high strength concrete is used more and more widely in engineering. The quality of construction is at the important position,and the rebound method has been widely used in nondestructive testing technology of concrete in the practical engineering,which is important in the analysis of the existing buildings’ ability to withstand natural disasters and reliability of continue to use after a disaster, the quality evaluation of structure construction, the ageing and durability evaluation of bridge and so on. For the medium-sized rebound hammer which is wildly used in the rebound method is weak to test the high strength concrete, putting forward the high strength concrete rebound hammer which impact kinetic energy is greater through consulting the related literature at home and abroad and learning the theory of rebound method to detect concrete strength. This paper conducted the following research:Based on its impact kinetic energy is larger, prepared different strength grade concrete test block of different ages, which for hebei regional environment and raw materials, in the laboratory. Using conventional medium rebound hammer and high rebound hammer test data, analyzed two kinds of instrument detection accuracy for strength of different period of concrete block and high strength concrete applicability problem through the regression of the data and error analysis. Determined that the 55 MPa is the change point of the two kinds rebound hammers’ accuracy. When the intensity of concrete members is under 55 mpa, using medium hammer which is more accurate and lighter than high strength concrete rebound hammer as the preferred. And for design strength grade of concrete members that is C50 and above, recommended high strength concrete rebound hammer of type HT1000 to test.In view of the environmental humidity and temperature’s influence of concrete member development and surface performance in the process of concrete curing, through the analysis of strength development of concrete block under different curing’s observation and the different impacts on the two kinds of hammer test concrete block in different curing conditions, determined the influence of curing conditions on the high strength concrete strength development and rebound method, which further compare the advantages and disadvantages of two different kind hammer.Based on the limitations of the rebound method which is a single index method, applied ultrasonic-rebound combined method, established ultrasonic-rebound strength curve which suitable for high strength concrete detection in hebei area to provide technical support for a more accurate detection of high strength concrete member in the construction site.