A PRELIMINARY INVESTIGATION OF TEST METHODS FOR THE ASSESSMENT OF STRENGTH OF IN SITU CONCRETE

A number of tests for assessing the strength of in situ concrete have been developed in recent years. The work described in this report has attempted to compare and evaluate these tests and determine their usefulness for assessing concrete strength in structures. In general, all the tests can be used to obtain an estimate of concrete strength which can be used as an aid to engineering judgement. The tests are likely to be most useful for comparing elements of nominally the same concrete when one element is suspect for some reason, as it is easier to estimate strength differences than actual strength values. The following tests are discussed: core test, ultrasonic pulse velocity test, pull-out tests, Norwegian break-off test, Schmidt hammer test, Windsor probe test, point-load core test. Recommendations for future research on individual test method are considered. (TRRL)