A test method for simulating the weakened interface of coarse aggregate-mortar

Abstract

The invention belongs to the technical field of construction engineering, and discloses a test method for simulating a coarse aggregate-mortar weakening interface, which mainly includes: making a cylindrical rock core aggregate, putting the rock core aggregate into water and standing until it is taken out before pouring Standby; attach the ground rubber fine particles to the surface of the core aggregate; pour mortar around the core aggregate to obtain a composite specimen; carry out a loading test on the composite specimen on the testing machine, and apply pressure on the surface of the core aggregate Load until the core aggregate is extruded out of the composite specimen, and the shear strength and bond-slip properties of the simulated coarse aggregate-mortar weakened interface are obtained. The present invention utilizes that the fine rubber particles with sufficiently small particle diameters have strong adhesiveness, and rely on their own adsorption force to adhere to the surface of the rock core aggregate. When the rock core aggregate with worn rubber fine particles is combined with the mortar, the worn Fine particles will reduce the contact area between mortar and coarse aggregate, weaken the friction and bonding performance between mortar and coarse aggregate, and achieve the effect of simulating a weakened interface.

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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