Abstract
Abstract Mortar is an important component of concrete. It is of great significance to obtain its tensile properties accurately. The structure heterogeneity of mortar specimens is high. Specimens are prone to fracture nearby interfaces between specimens and loading plates because of the inhomogenous stress distribution during the testing, which leads that effective tensile data can not be easily obtained. Therefore, through the improvement of specimen’s geometrical structure, the dumbbell specimen is designed for quasi-static direct tensile tests. Compared with the splitting test results, the quasi-static direct tensile testing of dumbbell specimens can be availably conducted to obtain the tensile strength. It also provides an effective approach to obtain the tensile parameters of mortar specimens. Moreover, numerical simulations on dumbbell specimens of mortar with different shapes are also conducted to explore the optimal geometrical structure in dynamic direct tensile tests.
Highlights
Received: October 30, 2017 In Revised Form: May 06, 2018 Accepted: May 14, 2018 Available Online: May 16, 2018Concrete-like materials are widely used in civil construction and military structures, like hydroelectric dams, road tunnels, building constructions and other infrastructures
GB/T 50081-2002 (Standard for Test Method of Mechanical Properties on Ordinary Concrete) mentions the validity of experimental results: ‘When there are three measured data and a ratio between the difference-value and intermediate strength is less than 15% and another ratio of that is more than 15%, the intermediate strength can be regarded as the strength of mortar specimens; if the ratio between the difference-value and intermediate strength are both larger than 15%, the experimental results are invalid; in addition, the average strength can be taken as the strength of mortar specimens as long as there are three measured data and the two ratios between the difference-values and intermediate strength are both less than 15%’
The experimental results of quasi-static splitting testing can not represent the tensile strength of mortar specimens
Summary
Received: October 30, 2017 In Revised Form: May 06, 2018 Accepted: May 14, 2018 Available Online: May 16, 2018. Available results from quasi-static and dynamic testing of mortar specimens are very limited because mortar specimens have greater structure heterogeneity than other concrete-like materials. There still exist some technical problems in quasi-static direct tensile tests, such as eccentricity loading and specimen clamping When the both axes of cylinder specimens and loading device are not overlapped under tension, the eccentric loading will likely happen in the testing process and lead to the wrong measurement. Shu Zhang et al Experimental and numerical investigation on the dumbbell-shaped specimen of concrete-like materials under tension ble in direct tensile tests with the clamping connection or adhesive bonding. The quasi-static tensile experiments of cylindrical mortar specimens are conducted and specimens of dumbbell shape is considered to reduce the stress concentration on specimen interfaces and improve the accuracy of experimental results in this study. Based on parameters determined by Zhang et al (2016), dynamic direct tensile test models of dumbbell specimens are established and the parametric analysis about specimen shapes is conducted in this paper
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