Study On Evaluation Of Long Curing Concrete Strength By Ultrasonic-rebound Combined Method

Concrete bridge in longer service due to the load and the role of environmental factors, the phenomenon of degradation will gradually appear; at present, with the country's rapid economic development,the transport services of Jilin Province also will continue to improve,the road and bridge face upgrade, traffic continues to increase, new, large transport vehicles increase and other issues, increasing the load on the bridge, internal and external interaction, leading to the bridge may be affected to some extent, so making the evaluation of the securityof bridge timely and accurately without damaging the bridge structure and does not affect the use of the premise is essential. Non-destructive testing of concrete strength in the practical applications, due to operation of simple technology, high accuracy, low-cost, no damage to the structure and other reasons, ultrasonic rebound method is most widely in application, supporting the use of the "Law of Rebound Technical specification for concrete strength testing "(CECS02:2005) national standards. Regulations applicable to the detection of 7 to 2000 days old concrete structure, obviously the unified national strength curve does not apply to the strength testing of long curing concrete bridge; at the same time, the order pointed out that as china's vast,concrete variety, process numerous national unity strength curve is difficult to adapt to the situation around the country, the proposed areas where conditions may be advised to establish local strength curve, in order to improve the accuracy of evaluation in the actual strength of concrete.Obviously it is urgent and practical to establish the special strength curve for long curing concrete bridge of Jilin Province.In order to establish the long curing concrete bridge strength curve Jilin Province, mainly in the following:1,Based on the analysis and summarization of the factors influencing the intensity of concrete, the important content is selected to be studied.2,Some common raw materials which usually adopted Jilin province are used to make certain amount of concrete standard samples,through the artificially accelerated carbonation of theâ…¢ concrete in a short time to reach a certain depth of carbonation of concrete to simulate the performance of long curing concrete, Many experiments have been carried through with these concrete samples using ultrasonic-resilient method respectively, and data are gained. The power function is used to regress. Concrete intensity test curves adaptable to this area is obtained through comparison and optimization using correlation coefficient.3,The precision of this intensity measuring curve is verified higher than country criterion by the comparison between the practical data with the reserved samples in laboratory.This project solves the unreasonable method and great error caused by using the correlative method and data in country standard to calculate the concrete grade.The local curve for detecting strength of conerete by ultrasonic-rebound combined method provides scieniific approach and warrant for technical identification, consolidation and maintenance, and reasonable rehabilitation of existing bridges.Therefore,the local curve for detecting strength of concrete by ultrasonic-rebound combined method has extensive application foreground, and brings huge Social benefit surely.