Size Effect of Concrete Specimens on the Acoustic Emission Characteristics under Uniaxial Compression Conditions

Abstract

Acoustic emission (AE) experiments under uniaxial compression and cyclic loading-unloading compression conditions were performed using different sizes of cubic concrete specimens. The influences of the loading methods and the concrete sizes on the mechanical parameters and the concrete AE activities were analyzed. The loading method was found to have great impact on the deformation, failure, and energy dissipation of concrete materials. With the increase of the material size, the uniaxial compressive strength of the concrete specimens gradually decreased, while the corresponding strain of peak strength increased first and then decreased. The elasticity modulus fluctuated irregularly. Under the uniaxial compression conditions, five AE patterns corresponding to the deformation and failure of the concrete materials were observed. A significant nonlinear relationship was found between the AE and the stress level. The cumulative AE rings at the peak stress showed nonlinear growth with the increase of the concrete size. Based on an established relationship between the cumulative AE rings and the stress level, the necessary conditions for the existence of the quiet AE period were given. Under the uniaxial cyclic loading-unloading compression conditions, the Felicity ratio decreased first and then increased as the stress increased. The research results have some guiding significance to AE-based monitoring of internal stress evolution of coal, rock, and concrete materials and thereby enable assessment of their stability.

Revealing the Proximity of Concrete Specimens to Their Critical Damage Level by Exploring the Cumulative Counts of the Acoustic Emissions in the Natural Time Domain

“…Along the same lines, it has been shown that the energy release rate, as it is recorded by the AEs technique, obeys a power law at the stage of intense internal damage [ 45 ]. Similar observations are reported for the cumulative AE rings, the evolution of which, at loading levels close to those causing fracture, is dictated by a strongly non-linear law [ 46 ].…”

Investigation of the Effect of Nanometakaolin on the Compression Behavior of Concrete by Acoustic Emission

“…The calculated b value is usually divided into three types: stress level, number of AEs, and crack propagation stage. − For the comparative analysis, the value of b in this section is the level of relative stress increase per 0.1. As can be seen from Figure , the b value exhibits a rising, fluctuating, and continuously decreasing variation law in the three types of concrete compression processes, but the magnitude of the b value and the range of the fluctuations are significantly different.…”

“…Crack initiation strength and crack damage are critical to distinguishing between crack initiation and unsteady propagation. Therefore, the AE signal variation characteristics can accurately reflect the crack initiation and propagation law of concrete, the same as the moving point regression method and the stress–strain curve observation method. , Crack initiation strength and crack damage stress are critical to distinguish between crack initiation and unsteady propagation. Tensile cracks are the dominant crack morphology.…”

Influence of Different Grouting Parameters on Mechanical and Strain Energy Characteristics of Different-Length Fractured Limestone in a Coalfield North of Yellow River: A Numerical Study Based on Particle Flow Code

“…In order to reveal the influence of grouting on the mechanical characteristics of fractured rock, domestic and foreign scholars have conducted a lot of research on it through indoor tests and numerical simulation [7,8] and further studied the mechanism of grouting reinforcement on this basis [9][10][11][12][13]. Yang [14] studied the structure of randomly fractured rock mass, the law of grouting permeability, the characteristics of randomness and anisotropy, and the stability of grouting reinforcement.…”