Strength assessment of a high rise concrete building using a combined NDT and DT method

Evaluation and assessment of in-place strength of concrete in existing structures have been carried out in many rehabilitation and retrofitting projects. A study was carried out on a 24 stories concrete building to ensure site supervisors and managers the in-place strength of concrete that may be in doubt. Although NDT tests for evaluation of concrete strength are very cost effective and convenient methods, the results are sometimes scattered. In this study an NDT method (Schmidt Hammer) in conjunction with a DT method (coring) was carried out to acquire a reasonable data about the strength. The number and locations for coring were selected so that the uncertainty raised by Schmidt hammer test was reduced. The results show that for a big concrete structure, using numerous NDT tests in conjunction with a limited number of DT tests can lead to rational and reliable results for structural assessors and supervisors.