Quasi-static and dynamic experimental studies on the tensile strength and failure pattern of concrete and mortar discs

Xiaochao Jin,Xueling Fan,Chunsheng Lu,Huawei Yang,Xuefeng Shu,Cheng Hou,Zhihua Wang

doi:10.1038/s41598-017-15700-2

Xiaochao Jin, Xueling Fan + Show 5 more

Open Access

https://doi.org/10.1038/s41598-017-15700-2

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Abstract

As concrete and mortar materials widely used in structural engineering may suffer dynamic loadings, studies on their mechanical properties under different strain rates are of great importance. In this paper, based on splitting tests of Brazilian discs, the tensile strength and failure pattern of concrete and mortar were investigated under quasi-static and dynamic loadings with a strain rate of 1–200 s−1. It is shown that the quasi-static tensile strength of mortar is higher than that of concrete since coarse aggregates weaken the interface bonding strength of the latter. Numerical results confirmed that the plane stress hypothesis lead to a lower value tensile strength for the cylindrical specimens. With the increase of strain rates, dynamic tensile strengths of concrete and mortar significantly increase, and their failure patterns change form a single crack to multiple cracks and even fragment. Furthermore, a relationship between the dynamic increase factor and strain rate was established by using a linear fitting algorithm, which can be conveniently used to calculate the dynamic increase factor of concrete-like materials in engineering applications.

Highlights

Concrete-like materials have been playing an invaluable role in structures and constructions
Taking inertial and strain rate effects into account, dynamic increase factor (DIF) obtained from dynamic splitting tests may overestimate the dynamic strength of concrete-like materials and cause potential security problems of structures subjected to earthquakes, blasting and hard impact[2,6]
Previous results show that, when the ratio of thickness to diameter for a Brazilian disc (BD) specimen is equal to 0.5, the inertial effect can be minimized and DIF is mainly contributed by the real strain rate effect[14,15,16,17]

Summary

Introduction

Concrete-like materials have been playing an invaluable role in structures and constructions. When the strain rate is in the range of 1–200 s−1, DIF is difficult to be accurately determined[2,3,5,6,9,10] since it is rapidly increasing and appears obviously higher than that at a lower strain rate (see Supplementary Fig. S1) This is what just happens for construction structures under impact loadings (see Supplementary Fig. S2), and there are few relevant studies reported on their dynamic strength. Taking inertial and strain rate effects into account, DIF obtained from dynamic splitting tests may overestimate the dynamic strength of concrete-like materials and cause potential security problems of structures subjected to earthquakes, blasting and hard impact[2,6]. It is necessary to conduct further investigation to highlight their different failure modes and dynamic tensile strengths under various strain rates

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Results

Conclusion