APULOT test: a tool for concrete’s quality control based on bond performance

The APULOT test, or bottle test, is a cheap and simple alternative to cylindrical specimens that can be applied in those regions where conventional quality control is difficult to introduce due to the lack of apropriate means. Specimens for this test are produced by casting concrete into an empty plastic bottle (the mould) with a reinforcing bar longitudinally centered, so that the result is a bottle-shaped concrete specimen with an embedded rebar. At the desired age, the rebar is simply pulled out of the concrete specimen, and the maximum pulling force achieved is the parameter used for quality control. A considerable number of bottle specimens and cylindrical specimens have been produced and tested according to a statistically designed experiment. It has been investigated how different parameters affect the bottle test results and their relation to compressive strength of concrete in order to compare the reliability of the bottle test with the conventional assessment of compressive strength by means of cylindrical specimens for quality control. All results have been analyzed by means of analysis of variance, multiple linear regression and logistic regression. These analyses have made possible: the identification of the best configuration of the parameters considered to be taken into account for an eventual standardization of the test, and finding expressions showing how the test results are to be translated in terms of concrete compressive strength.