Testing Plan for Estimating In Situ Concrete Strength

Abstract

The British Standards Institution (BSI) permits core and nondestructive tests (NDTs), such as ultrasonic pulse velocity (UPV), rebound hammer, and pull-out tests, to estimate the in situ compressive strength of existing concrete structures. The ASTM test method, in addition, also permits the use of a penetration resistance test (e.g., Windsor probe). Sound engineering judgment and the appreciation of factors influencing each NDT and core test are required in developing the testing plan for estimating in situ compressive strength of concrete structures. There are precautions and practical considerations that must be recognized. The issues in using such tests for estimating in situ compressive strength would be discussed. The different approaches of the BSI codes to determine the in situ strength are illustrated with examples. Results obtained are compared to demonstrate the practical limitations of such approaches. Using any one of the NDTs or core tests yielded estimated in situ concrete compressive strengths that differed substantially.