Test method for simulating coarse aggregate-mortar weakened interface

Abstract

The invention, which belongs to the technical field of construction engineering, discloses a test method for simulating a coarse aggregate-mortar weakened interface. The method mainly comprises: making a cylindrical core aggregate, placing the core aggregate in water, carrying out standing processing till pouring, and taking out the processed core aggregate for standby; attaching ground rubber particles to the surface of the core aggregate; pouring mortar around the core aggregate to obtain a composite test piece; and carrying out loading testing on the composite test piece on a testing machine, applying a pressure load on the surface of the core aggregate till extrusion of the composite test piece from the core aggregate to obtain anti-shear strength and bond-slip characteristics of the simulated coarse aggregate-mortar weakened interface. According to the invention, the rubber fine particles with sufficiently small particle diameters have the strong adhesiveness and are attached to the surface of the core aggregate based on the own adsorption forces; when the core aggregate with the worn rubber fine particles attached is combined with the mortar, the contact area between the mortar and the coarse aggregate is reduced based on the worn fine particles; and the friction and bonding performances between the mortar and the coarse aggregate are weakened, so that the effect of simulating the weakened interface is realized.

Description

technical field [0001] The invention belongs to the technical field of construction engineering, and in particular relates to a test method for simulating a coarse aggregate-mortar weakened interface. Background technique [0002] At the mesoscopic level, concrete is usually regarded as a heterogeneous composite material composed of aggregate, mortar and the interface transition zone between them, and its stress shows obvious nonlinearity and randomness. [1] . Compared with aggregate and mortar, the interfacial transition zone has lower density, lower strength, and lower elastic modulus, which is the "weak link" in concrete. During the long-term service of the concrete structure, due to the chemical shrinkage caused by the hydration of the mortar and the dry shrinkage caused by the evaporation of unhydrated excess water, as well as the repeated influence of the temperature load caused by the difference in thermal expansion coefficient between the coarse aggregate and the mo...

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Problems solved by technology

However, the above tests did not consider the defects in the interface transition zone after the long-term service of concrete, and were only suitable for new specimens, with obvious errors

Wu Jing and others [9] Applying waste engine oil on the aggregate weakens the aggregate-mortar interface, and artificially introduces micro-cracks in the interface transition zone, so that the defects are evenly distributed in the interface. The test explores the influence of the strength of the interface on the performance of concrete. And analyzed the crack propagation mode under the action of external load, but this simulation method will amplify the weakening effect and increase the experimental error; Prokopski G et al. [3] The surface of the aggregate was treated with paraffin, and the results showed that the compressive strength of the concrete would be reduced by at least half after the surface of the aggregate was treated. Highly affected by environmental factors

[0004] In summary, the performance of the coarse aggregate-mortar interface largely affects the macroscopic mechanical properties of concrete. However, due to the limitation of the test method, it is not yet possible to effectively and truly simulate the weakened coarse aggregate-mortar after long-term service. interface, and cannot directly test the mechanical properties of the interface transition zone

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