Estimation of compressive strength based on Pull-Out bond test results for on-site concrete quality control

Abstract

Quality control of structural concrete has been conducted for several decades based mainly on the results of axial compression tests. This kind of test, although widely used, is not exempt from errors and has some considerable drawbacks that may affect its reliability, such as the need for appropriate and careful specimen conditioning and adoption of adequate capping techniques. For these reasons, it would be useful to have complementary or alternative ways to check compressive strength, in order to improve concrete quality control. The use of a bond test to monitor concrete strength is being proposed by an international group of researchers from France, Tunisia and Brazil as a potential means to this end. Given the fact that the link between bond resistance and concrete strength is already well established, this type of test seems to be a viable alternative to traditional methods. Nonetheless, to check if the underlying principle is sound when used in different circumstances, the group has been gathering data from several studies conducted by different researchers in various countries, with distinct concretes and rebar types. An analysis of the data collected shows that there is a clear and strong correlation between bond resistance and compressive strength, no matter the influence of other variables. This result validates the basic idea of using an Appropriate Pull-Out (APULOT) bond test to assess concrete strength. If the general principle is valid for random data obtained from different studies, the definition of a clear and appropriate test will probably lead to the reduction of experimental noise and increase the precision of the strength estimates obtained using this method.Keywords: bond stress, concrete compressive strength, quality control of concrete, pull-out test.O controle de qualidade do concreto estrutural vem sendo realizado, há várias décadas, baseado principalmente nos resultados de ensaios de compressão axial. Este tipo de ensaio, embora amplamente utilizado, não está isento de erros e tem algumas desvantagens consideráveis que podem afetar sua confiabilidade, tais como a necessidade de condicionamento adequado e cuidadoso dos corpos-de-prova e de adoção de adequadas técnicas de nivelamento e capeamento. Por estas razões, seria útil ter maneiras complementares ou alternativas para verificar a resistência à compressão, a fim de melhorar o processo de controle de qualidade do concreto. O uso de um ensaio de arrancamento para monitorar a resistência do concreto está sendo proposto por um consósrcio internacional de pesquisadores da França, Tunísia e Brasil como um meio potencial de atingir essa meta. Dado que a existência de uma relação direta entre a tensão de aderência e a resistência do concreto já está bem estabelecida, este tipo de teste parece ser uma alternativa viável aos métodos tradicionais. No entanto, para verificar se o princípio subjacente é valido quando usado em diferentes circunstâncias, o grupo tem buscado recolher dados de vários estudos, realizados por diferentes pesquisadore...

Post-installed screws for in-situ assessment of mortar strength

“…With sufficient level of confinement surrounding the bar, failure pattern is dominated by pullout failure characterized by crushing of concrete under the deformation of the bar. In case of complete pullout failure, ultimate failure load is affected by compressive strength of concrete indicating a close relationship between bond strength and compressive strength of concrete (B. V. Silva et al 2014a, B. D. V. Silva et al 2014b, Lorrain & Barbosa 2011.…”

Influência da adição de fibras de aço na tensão de aderência de barras de aço retilíneas

“…(1) CP10. 10 (2) the pull-out of the bar happened after the yield stress of the steel, but before its failure; (3) the failure happened in the bar, without it being pulled out.…”

“…In literature, there exist several tests that allow determining the bond stress-slip relationship. These tests can be basically subdivided in bar pull-out tests [3][4][5][6][7][8][9][10], beam bending tests [6,[11][12][13], and direct traction tests on rods (or concentric pull-out test) [14]. This last test consists of concreting two bars at the extremities of a concrete prism, one of those being pulled-out due to its shorter anchorage length.…”

Artificial neural networks application to predict bond steel-concrete in pull-out tests

“…The research group APULOT has been working hard in studies to check the possibility of using the results of the testing of bond steel-concrete for estimating compressive strength of concrete. The authors Silva (2010) [3]; Lorrain et al (2011) [4] show that the correlation between these variables is valid and it is possible to make appropriate estimates of compressive strength. However, to get appropriate responses of steel-concrete bond tests it is necessary to control the settings, considering, among other parameters, the existence of various shapes of specimens for these types of tests.…”