A partially destructive method for testing In-situ strength of concrete

Abstract

Core test is commonly required in the area of concrete industry to evaluate the In-situ compressive strength of concrete and sometimes it becomes the unique tool for safety assessment of existing structure. Core test is therefore introduced in most of the codes. The current method of core testing involves the use of compression tests on cylindrical specimens obtained from cores drilled in-situ. The cores are damaged during extraction, transportation, more time and money involved during sawing and capping and sometimes cores are misplaced and also there is misinterpretation of strength due to variation in site and laboratory conditions. In order to overcome the difficulties, a new machine which simplifies the entire tedious testing process has been developed and used in this research work for testing of concrete strength within the structure. The principle of the machine is to test the un-extracted core with lesser diameters within the site for its Compressive strength. To test the reliability of the machine, cores of different diameters and L/D ratios were tested both by conventional method and newly developed machine and Comparative statistical analysis such as Student's t-test analysis is done to check the homogeneity of data and the general similarity between the results of Conventional method and the newly developed machine. Nearly 54 core samples of 24mm, 36 samples of 42mm and 36 samples of 67mm diameter of L/D ratios 1.0, 1.5, 2.0 were tested. The statistical analysis like Student's t-test proved that there is no considerable difference in the newly developed method and the conventional method of concrete core testing.