Application Research Of Concrete Strength Inspection Technique In Building Structures

Strength of concrete is a key factor to determine the load-carrying capacity of concrete structures. Therefore, the concrete strength inspection technique becomes an important part in building structural inspection, which is composed of the methods of non-destructive test and part-destructive test. Method of non-destructive test could be carried out by surface impress analysis, rebound method, vibration exam, ultrasonic-rebound combined method. Method of part-destructive test normally is conducted by drilled core method, pull-out test, penetration test, breaking test and stripping test. Amongst them there are three methods to be used widely in present inspection of building structural, respectively rebound method, ultrasonic-rebound combined method and drilled core method. Through analyzing the precision of three methods by means of comparing the applications in real projects, a strategy was given for how to select methods of concrete strength inspection.The practical application of rebound method, ultrasonic-rebound combined method and drilled core method in projects shows that the former two are more efficient and convenient in detecting cracking and assessing the concrete quality while the last one is the best method in direct assessment of the strength of inner structural members. Both rebound method and ultrasonic-rebound combined method are suitable for the big area to obtain the massive information. Among these information, including speculating concrete compressive strength, even"the sound","the sonic speed"could be used to carrying on the concrete quality uniformity inspection, seeking the weak spot, surveying the crack. Then either the bearing capacity or the distortion performance could be purposive controlled or processed.Drilled core method is a test for directly converting the sample's exam results into values of concrete compressive strength. Both ultrasonic-rebound combined method and rebound method belong to the indirect test method, of which relations between the compressive strength and test-indexes must be established to deduce the concrete compressive strength, namely the strength equation. Simultaneously the errors of ultrasonic-rebound combined method and rebound method are big because of the carbonization and many other condition limit. Thus drilled core method is more accurate than ultrasonic -rebound combined method and rebound method and can be used to adjust the accuracy of the other test methods. Along with the social development, the sweeping change are taken place among the height of the reinforced concrete structure system, the complex degree of the construction and the design, the concrete structure material constitution and so on. Many limits are created the concrete strength inspection on structures. The minor diameter drilled core method could be still adopted to inspect concrete strength in practice, the accuracy of which is able to satisfy the request of inspection. Based on the comparison analysis, a strategy will be given for selecting appropriate methods in assessing the compressive strength of concrete structure. The reliability of the concrete compressive strength inspection data could be effectively enhanced through combining of non-destructive test and part-destructive test reasonably.