Abstract
According to the principle and method of drop-weight impact test, the impact resistance of concrete was measured using self-designed U-shape specimens and a newly designed drop-weight impact test apparatus. A series of drop-weight impact tests were carried out with four different masses of drop hammers (0.875, 0.8, 0.675 and 0.5 kg). The test results show that the impact resistance results fail to follow a normal distribution. As expected, U-shaped specimens can predetermine the location of the cracks very well. It is also easy to record the cracks propagation during the test. The maximum of coefficient of variation in this study is 31.2%; it is lower than the values obtained from the American Concrete Institute (ACI) impact tests in the literature. By regression analysis, the linear relationship between the first-crack and ultimate failure impact resistance is good. It can suggested that a minimum number of specimens is required to reliably measure the properties of the material based on the observed levels of variation.
Highlights
As it is known, concrete is one of the most widely used building materials in modern architectures.in civil engineering, all kinds of concrete structures inevitably encounter dynamic load duringMaterials 2015, 8 the design lifetime, except in the case of static load [1,2]
In order to force cracks to occur in a predefined path during the test, the concrete specimens were made into U-shape, which would cause crack initiation and ensured that the specimens were destroyed in the middle of them
The according to summary of of statistical statistical parameters compression tests, of
Summary
Concrete is one of the most widely used building materials in modern architectures. Charpy-type impact test; (b) drop-weight test(single or repeated impact); (c) constant strain-rate test; (d) projectile impact test; (e) split-Hopkinson pressure bar (SHPB) test; (f) explosive test; and (g) instrumented pendulum impact test None of these tests has been declared to be a standard test, at least in part due to the lack of statistical data on the variation of the results, and comparisons between any of the above tests are very difficult. Some of these tests are relatively difficult to perform and require sophisticated equipment In this regard, ACI Committee 544 [11] has proposed a drop-weight impact test to evaluate the impact resistance of concrete. By using the regression technique, linear relationships between the first crack and ultimate failure impact resistance in blows were proposed; based on the theory of statistics, the minimum number of specimens in tests of concrete impact resistance was proposed to keep the error within a certain limit
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