Keywords: bond strength, in-situ strength, pull-off test, concrete repair, civil engineering, compressive strength, concrete strength, patch repairs, quality control, long-term monitoring, hardened concretes
State-of-the-art applications of the pull-off test in civil engineering
In 1974, the concept of using pull-off test as a means of predicting the compressive strength of concrete was patented in the UK by Professor Long at Queen's University Belfast. Initially, the pull-off test was developed primarily aiming at unplanned in-situ strength determination. It was found later also particularly suited for assessment of bond strength of repairs. This test has now been accepted in British Standards, BS 1881-207:1992 for assessing the in-situ concrete strength in structures and BS EN 1542:1999 for assessing the bond strength between overlays and substrate concrete in patch repairs. In addition, BS 1881-201:1986 recommends it for quality control and long-term monitoring of hardened concretes. It has also been accepted in North America (ASTM C1583-04), Holland and some other countries for similar applications. This paper reviews its development history, principle, factors affecting the test results as well as its current applications in civil engineering fields.