Wave Attenuation Characteristics Research Articles

Stress Relaxing Simulation on Digital Rock: Characterize Attenuation Due To Wave‐Induced Fluid Flow and Scattering

AbstractDigital rock physics (DRP) is essential to understand the wave elastic and attenuation characteristics of complex porous rocks, offering insights into interpreting seismic and sonic logging data. Most of the existing DRP technology can only simulate wave‐induced fluid flow (WIFF) or scattering effects separately in a relatively narrow or single‐frequency band. To incorporate both the effects of WIFF and elastic scattering simultaneously, we develop a stress relaxing simulation (SRS) technique on digital rocks to characterize the P wave dispersion and attenuation signatures in a broad frequency band. We propose to use the combined methodology of curve resampling and wavelet‐packet denoising to suppress the high‐frequency noise of the stress relaxation curve. For a digital rock containing pore‐crack elements, we demonstrate that SRS is capable of characterizing the attenuation due to squirt flow and scattering as well as their interactions. The simulation results of wave dispersion and attenuation using SRS are overall consistent with other well‐developed DRP technology of transmitted wave simulation (high‐frequency band), forced oscillating simulation (intermediate‐frequency band), and static simulation (low‐frequency band), suggesting the reliability and robustness of the developed methodology. We also apply the SRS on a realistic 2D digital rock of porous sandstone. It is found that the attenuation due to elastic scattering of the microscopic heterogeneities is significantly higher than that caused by squirt flow, which might be caused by the lack of pore connectivity impeding the fluid exchange at the microscopic scale due to the limitation of 2D digital porous rocks.

Study on wave attenuation on a coral reef flat in SCS by in-situ measurement and simulation

There has been no quantitative assessment of the wave attenuation coefficient on the coral reef flat in South China Sea (SCS) previously. Based on MIDAS DWR (Directional Wave Recorder), an in-situ experiment was carried out on a coral reef flat of Yongle Atoll, SCS. Waves and currents were measured at several locations on the reef flat, which were used to estimate wave attenuation due to bottom friction. A spectral wave model based on the action density balance equations is proposed to solve the wave attenuation coefficients on the coral reef flat, which can consider influence of currents. The wave attenuation coefficients due to bottom friction on the coral reef flat were found to be one order of magnitude greater than that recommended in most spectral wave models. Additionally, numerical simulation using a third-generation wave model SWAN was carried out. The simulation results verify in turn that the bottom friction plays a predominant role in the wave attenuation on the coral reef flat. It also captures the main characteristic of wave directional spectra with high precision. The study of the wave attenuation characteristics near islands and reefs will lay a foundation for the mechanism of wave propagating near islands and reefs.

Investigation of pressure wave propagation and attenuation characteristics in managed pressure drilling by fast switching throttle valve

Pressure waves possess many significant applications in the oil and gas drilling engineering field, such as mud pulse telemetry (MPT) and measurement while drilling (MWD). The focus of this research is to study the pressure wave propagation and attenuation characteristics of wellbore liquid-phase flow in managed pressure drilling (MPD) by fast switching throttle valve (FSTV). First, a mathematical model of transient pressure wave propagation along the wellbore in both upstream and downstream directions is proposed in MPD by FSTV based on the one-dimensional transient flow theory. The model considering the frictional shear effect between the pipe walls is solved by utilizing the method of characteristics. Meanwhile, boundary conditions at the drill string inlet and annulus outlet, at the throttle valve, at the junction of drill bit, and at the reducer are adequately taken into account according to the actual situation of fluid flow. Second, a laboratory experiment of excited pressure waves in a vertical wellbore is conducted to measure the variation of the pressure fluctuation with different pump rates by FSTV. Comparing with the measurement result, the calculation result is discovered that the overall change is consistent, where the maximum absolute relative error at the peak of the pressure wave is only 4.5%. Finally, it further analyzes influential factors affecting the propagation and attenuation behaviors of wellbore pressure waves in liquid-phase flow based on the model. The results indicate that pressure waveforms present sinusoidal wave propagation, and pump rates, pressure wave speed, excitation time, fluid type, mud density, fluid viscosity, and borehole size exert varying degrees of influence on downhole pressure fluctuations. The proposed model achieves accurate quantitative interpretation and analysis of downhole pressure wave in MPD by FSTV, which has important significance for the realization of safe and efficient drilling.

Numerical Modelling of an Innovative Conical Pile Head Breakwater

When moderate wave activity at the shoreline is acceptable, pile breakwaters can serve as an alternative to conventional breakwaters. Increasing the size of the pile breakwater in the vicinity of the free surface increases the hydraulic efficiency, as most of the wave energy is concentrated around the free surface. Therefore, a conical pile head breakwater (CPHB) is proposed in the present study by gradually widening the diameter of the piles towards the free surface. Using the open-source computational fluid dynamics (CFD) model REEF3D, the transmission, reflection, and dissipation characteristics of the CPHB with monochromatic and irregular waves are examined. The investigation is carried out for both perforated and non-perforated CPHBs using monochromatic waves, and the numerical results are validated using experimental data. Further, optimally configured non-perforated and perforated CPHBs are investigated numerically by subjecting them to irregular waves using the Scott–Wiegel spectrum. The wave attenuation characteristics of the CPHBs are found to be better with irregular waves compared to monochromatic waves. With irregular waves, the minimum transmission coefficients for non-perforated and perforated CPHBs are 0.36 and 0.34, respectively. Overall, the CPHB appears to be a potential solution for coastal protection.

Bandgap and Wave Propagation Properties of 2D Curved and Chiral Hybrid Star‐Shaped Metamaterials

Designing artificial microstructural metamaterials that fulfill the single‐phase vibration dampening and lightweight twin goals is challenging and critical. 2D curved and chiral hybrid star‐shaped metamaterials (CCHSM) are proposed to perform vibration reduction filtering in the midfrequency region by combining the properties of chiral structure and concave structure. The generating process of the bandgap of in‐plane elastic waves, the properties of directional attenuation, and the flow direction of energy in the dispersion curve are examined using the modal shape, dispersion surface, and group velocity. In a specific frequency range, the equivalent medium parameters satisfy the conditions of negative refraction transverse and longitudinal waves, so the structure also has double‐negative characteristics. The filtering performance is validated using the CCHSM periodic plate structure and a finite‐element simulation of transmission loss. In addition, the correlation between wave attenuation characteristics and structural parameters is explored. The radius of the circular arc and the deflection angle of the connecting rod have a significant impact on the frequency range of the structural bandgap. The results show that the created simple‐configured, single‐phase lightweight acoustic metamaterials exhibit strong local resonance properties and double‐negative features.

Polynomial eigenvalue solution for elastic wave prediction of piezoelectric shunting arrays

This paper presents a polynomial eigenvalue solution to predict the propagation behaviors of elastic wave in piezoelectric shunting arrays. Based on the Bloch theorem, one independent unit cell is selected to conduct the dynamic characteristic analysis instead of infinity. The reduced form of the discretized governing equations is first derived by the standard finite element procedures. To facilitate the subsequent acquisition of dispersion relationship, the dynamic stiffness matrix is then partitioned into a block matrix. Through applying the periodic boundary conditions, a polynomial eigenvalue equation concerning complex propagation constant is finally obtained. The wave propagation and attenuation characteristics in arbitrary directions are investigated using the above methodology. The results demonstrate that the present method can provide very accurate and reliable solutions for wave propagation prediction of piezoelectric shunting arrays.

Prediction of Wave Transmission Characteristics of Low Crested Structures Using Artificial Neural Network

<i>Recently around the world, coastal erosion is paying attention as a social issue. Various constructions using low-crested and submerged structures are being performed to deal with the problems. In addition, a prediction study was researched using machine learning techniques to determine the wave attenuation characteristics of low crested structure to develop prediction matrix for wave attenuation coefficient prediction matrix consisting of weights and biases for ease access of engineers. In this study, a deep neural network model was constructed to predict the wave height transmission rate of low crested structures using Tensor flow, an open source platform. The neural network model shows a reliable prediction performance and is expected to be applied to a wide range of practical application in the field of coastal engineering. As a result of predicting the wave height transmission coefficient of the low crested structure depends on various input variable combinations, the combination of 5 condition showed relatively high accuracy with a small number of input variables defined as 0.961. In terms of the time cost of the model, it is considered that the method using the combination 5 conditions can be a good alternative. As a result of predicting the wave transmission rate of the trained deep neural network model, MSE was 1.3×10<sup>-3</sup>, I was 0.995, SI was 0.078, and I was 0.979, which have very good prediction accuracy. It is judged that the proposed model can be used as a design tool by engineers and scientists to predict the wave transmission coefficient behind the low crested structure.</i>

Experimental Study on the Influence of Moisture and Clay Content on Stress Wave Attenuation Characteristics of Filled Joints

Artificial filled joints made of sand–clay mixtures with different clay weight fractions and saturations have different wave attenuation capacities. In this paper, the high amplitude impact test of sand–clay mixtures was carried out by using split Hopkinson pressure bar (SHPB) equipment. The results showed that with the increase of clay weight fraction, the particle crushing decreased continuously, while the wave attenuation coefficient decreased first and then increased. When the weight fraction of clay was 50%, the wave attenuation coefficient reached the minimum among the tested working conditions, and the ratio of transmitted energy to incident energy reached the maximum. With the increase of saturation, the particle crushing decreased first and then increased, while the wave attenuation coefficient increased first and then decreased. When the saturation was 25%, the wave attenuation coefficient reached the maximum, and the proportion of transmitted energy to incident energy reached the minimum. Because of the lubrication of water reduced the friction between particle, the specimen more prone to deformation and particle crushing reduced. As the saturation increased, this effect gradually decreased. In the case of the wave absorbing layer of protective works, special attention should be paid to the adverse effects caused by groundwater.

Blast shock wave attenuation in square cross-sectional truss based meso-scale lattice architectures

With the rapid growth in defense and civilian industry interests, high-performance materials like lattice materials capable of resisting high strain-rate loads are urgently required. Researchers mainly focus on the irreversible plastic deformation of lattice core sandwich structures under out-of-plane loads, whereas the potential application of cellular core without sandwiched face sheets has not been explored. In fact, when shock waves directly act on a cellular core without sandwiched face sheet, the energy would be consumed in the voids during the wave propagation. This article gives an insight into the shock wave attenuation characteristics and the attenuation mechanisms of square cross-sectional truss based meso-scale lattice architectures. Two types of lattice configurations with the same porosity but different truss sectional arrangements are employed. It is reported that both types of the lattice architectures can considerably dissipate the shock wave. The variation trends of overpressure-time history for the meso-scale lattice architectures are significantly different from those obtained in the free air field. As the truss-sectional size decreases the detected first peak overpressure decreases and becomes gradually lower than the second peak overpressure due to the increasing truss layers. When the edge length of truss section, d, decreases from 0.4 mm to 0.1 mm at a constant scaled distance of 0.896, the attenuation efficiency of the peak overpressure is increased by 30 % to 70 %, and the efficiency of the impulse is increased by 60 %, together with a highly-improved increasing rate for the delaying efficiency of the arrival time. Considering distinct scaled distances, the type II architecture and type I architecture behave superiorly with respect to the attenuation efficiencies of peak overpressure and impulse, respectively. Compared to the free field scenario, a shorter wave propagation distance could be observed for the meso-scale lattice architectures to achieve the same peak overpressure and impulse. The considerable shock wave attenuation of the meso-scale lattice architecture is attributed to the complex interactions of the shock wave reflection, diffraction, and superposition around the truss sections and in the voids. This investigation provides a novel method for the shock wave attenuation and energy consumption to protect vital targets and precise equipment.

Propagation and attenuation characteristics of shock waves in a gas–coal dust explosion in a diagonal pipeline network

In order to obtain the propagation and attenuation characteristics of a shock wave gas–coal dust explosion, a diagonal pipeline network was built to carry out a gas–coal dust explosion experiment. Methane with a volume fraction of 9.5% was mixed with 20 g of coal dust with a particle size of 50 μm. The shock wave attenuation characteristics in the diagonal pipeline network were characterized by the overpressure attenuation coefficient. The results showed that when the shock wave propagated in the diagonal pipeline network, it was offset and superposed multiple times. The overpressure attenuation in diagonal pipes was greater than that in the other pipeline branches. Secondary explosions occurred at all monitoring points. The propagation characteristics of shock waves is less affected by the pipeline network structure when it is close to the outlet of pipeline network. Nonlinear multivariate regression analysis was carried out to analyze the relationship between the overpressure attenuation coefficient and two adjacent monitoring points, the pressure before and after attenuation, and the pipeline angle. The functional relationship was in good agreement with the experiment data.

Influence of the Core Pillar Height on the Bandgap Characteristics of Piezoelectric Phononic Crystals with Ring-Shaped Grooves

Dispersion profiles and surface acoustic wave attenuation characteristics of ring-shaped phononic crystals are investigated as a function of the core pillar height. Finite element method simulations are carried out for both band analyses and transmission spectra calculations. The results reveal that increasing core pillar height results in a decrement in the local resonance band frequency and the corresponding transmission peaks. The obtained dispersion profiles show that the phononic crystal bandgap also expands from 6 MHz to 11 MHz while the pillar height increases from 5 um to 7 um. Similar characteristics are also seen in the transmission spectra for the varying core pillar heights of the ring-shaped periodic grooves. In addition, surface acoustic wave attenuation competency depends on the core pillar height. The frequencies where the investigated phononic crystals are functional can be tuned by adjusting the core pillar height.

Broadband low-frequency sound attenuation in duct with embedded periodic sonic black holes

This paper studies the sound wave propagation and attenuation characteristics in a new type of acoustic device, which is constructed by periodically embedding sonic black holes (SBHs) into an air-filled waveguide. The SBH is realized by cascading a set of rigid rings with linearly or quadratically changing inner radii into each unit cell section. Acoustic impedance variation rendered by this specially tailored profile progressively slows down the incident sound velocity to generate the SBH effects including wavelength compression, energy focalization, and dissipation with inherent damping in the duct. Upon developing and validating a model based on the transfer matrix method (TMM), the sound transmission loss (STL) of a finite-length periodic duct with different geometrical parameters is investigated. Different from a single SBH unit which can trigger the complete SBH process only above the cut-on frequency, the proposed periodic arrangement offers strong attenuation bands in the low-frequency range of the STL curve well below the frequency barrier imposed by the cut-on frequency of a single SBH unit. Mechanism studies reveal that these attenuation bands result from the interplay between the Bragg scattering and the SBH-specific slow-sound effects. The latter is shown to equivalently increase the effective lattice constant of the periodic duct, thus lowering the frequency of the Bragg bandgap. It is also shown that in contrast to conventional locally-resonant metamaterials, the proposed device exhibits far less dependence on the number of unit cells and the amount of rigid rings to activate a significant low-frequency stop-band. These appealing features could greatly simplify the design and application of SBH-based metamaterials, making it a promising solution for low-frequency wave manipulation and noise control.

Hydrodynamic Characteristics of Idealized Flexible Vegetation under Regular Waves: Experimental Investigations and Analysis

Wang, H.; Yin, Z.; Luan, Y.; Wang, Y., and Liu, D., 2022. Hydrodynamic characteristics of idealized flexible vegetation under regular waves: Experimental investigations and analysis. Journal of Coastal Research, 38(3), 673–680. Coconut Creek (Florida), ISSN 0749-0208. Salt marshes protect coastal communities from erosion and damage by damping incoming waves. A series of physical experiments were conducted to investigate the wave attenuation characteristics of idealized flexible vegetation, and the parameters of submergence, stem density, wave height, and wave length were considered. It was observed that the wave transmission coefficient decreased and the wave damping factor increased with increasing submergence ratio, relative wave height, and relative stem density and decreasing relative wave length. Moreover, the wave transmission coefficient decreased with increasing Ursell number. In addition, with an increase in the submergence ratio, relative wave height, Reynolds number, Keulegan-Carpenter number, and Ursell number, the bulk drag coefficient decreased. The bulk drag coefficient was more strongly related to the Ursell number than the other parameters. A simple equation for the wave transmission coefficient was constructed using the dimensional analysis method, the least squares method, and randomly selected experimental data, and it was effectively validated based on the other experimental data.

Research on power penetration cable line fault location based on distributed traveling wave location technology

The power penetration line of high-speed railway adopts all-cable lines, and its failure will seriously affect the safety and reliability of railway transportation. The accurate location of the fault will greatly reduce the range of finding the cable fault point and the workload of cable fault repair, shorten the maintenance time, and improve the reliability of high-speed railway power supply. This paper introduces the current situation of power line fault location, analyzes various traveling wave location principles and the traveling wave transmission and attenuation characteristics of all-cable penetration lines, and analyzes the adaptability of the traditional traveling wave location technology in all-cable penetration line fault location. It is proposed that the distributed traveling wave location method can greatly reduce the transmission distance of fault traveling waves and can effectively reduce the influence of attenuation and distortion in the traveling wave transmission process. For different types of fault traveling waves, different fault transition resistances, and different positions of fault points, the method can achieve the accurate location. The practical application case shows that the technology has high location accuracy and meets the requirements of a precise location.

Seismic Wave Attenuation Characteristics from the Ground Motion Spectral Analysis around the Kanto Basin

In order to study the seismic wave attenuation characteristics of complex plate tectonics in and around the Kanto Basin, based on the focal mechanism and Slab1.0 model, the research area is divided into four regions. The one-step non-parametric generalized inversion technique was used to analyze the seismic wave attenuation characteristics of each region separately. The results show that the seismic path attenuation of earthquakes occurring in the shallow crust (Reg.1) is weak, and the seismic wave refraction at the crust–mantle boundary leads to almost no attenuation over a long hypocentral distance (>60 km), the frequency–dependent inelastic attenuation is also weak with the 0.5–20 Hz quality factor Q = 92.33f1.87. The seismic path attenuation of the upper mantle earthquakes occurring in the Kanto Basin (Reg.2) is strong, and the attenuation curve decreases with the increase of hypocentral distance, which is approximately parallel to the geometric diffusion R−2.0, the frequency–dependent inelastic attenuation is stronger with the quality factor Q = 27.75f1.08. The seismic path attenuation of subduction zone earthquakes (Reg.3 and Reg.4) is more obvious in the high–frequency band and has a frequency correlation, indicating that the attenuation of subduction zone earthquakes includes more inelastic attenuation. The frequency–dependent inelastic attenuation Q of Reg.3 and Reg.4 are 52.58f0.95 and 58.07f0.89, respectively.

Wave attenuation prediction of artificial coral reef using machine-learning integrated with hydraulic experiment

Various prevention methods have been proposed to resolve such coastal erosion problems, known as an important social issue in many countries. However, most of the methods designed and constructed involve gravity-type structures, causing various problems such as the obstruction of seawater circulation and changes in water quality and marine ecosystem. In this study, we propose an eco-friendly artificial coral reef structure that can control coastal erosion and help preserve the coastal environment. We investigated the wave height distribution and energy reduction characteristics through a two-dimensional hydraulic model experiment under various conditions, including different external force conditions (wave height, water depth, and wave period) and design conditions (dimensionless crown width and submergence ratio). Furthermore, we investigated the drift sand control and morphological characteristics of artificial coral reefs through a movable bed experiment. The results of the hydraulic experiment revealed that the dimensionless crown width and submergence ratio factors had a dominant effect on the wave height attenuation. In addition, the artificial coral reef structures outperformed broadly applied tetrapod structures in terms of coastline advancement and seabed protection under storm wave conditions. Moreover, to estimate the wave attenuation characteristics of artificial coral reefs, we introduced a prediction study of wave attenuation characteristics of artificial coral reefs to propose an explicit method composed of weights and biases using modified artificial neural network. We found that the method of calculating the wave dissipation coefficient calculated with the presented weight and bias matrix shows more accurate reliability than the calculation method based on the existing empirical formula.

Azimuthal Path Variations of Regional Body Wave Attenuation via Coda-Source Normalized Method: An Example from Eastern Marmara (NW Turkey)

ABSTRACT This study examines the body wave attenuation characteristics for the eastern section of the Marmara Region (NW Turkey). Qp and Qs values were obtained using the vertical and two horizontal components of the three-component broad-band data, respectively that recorded in a circular areal extent with 120 km radius centred at the ARMT station on the Armutlu Peninsula. The database was prepared according to back-azimuthal distributions, and data-packs representing 36 different back-azimuthal slices were subjected to the Extended-Coda-Normalization-Method to examine the azimuthal path-dependence of the attenuation characteristics of direct body waves in the region. While the region corresponding to the basins in the Marmara Sea with relatively low seismicity is represented by high Q values, low Q values were observed in areas with intense faulting and seismicity in the NE of the study area. Additionally, direction-independent attenuation functions for the region were calculated as Qp = 18 ± 1f0.92±0.2 and Qs = 38 ± 1f0.87±0.01 for P and S phases, respectively.

Results and prospects of seismological observations in the central part of the Baikal rift

This article reports the results of detailed seismological observations in the Central Baikal region conducted by the local network of seismological stations of the Buryat Division of the Geophysical Survey of the Russian Academy of Sciences. The local network was created in the 1990s. A crucial feature of the network is the combination of seismic monitoring both in the passive mode (the study of natural seismicity) and in the active mode, with a controlled vibration source of seismic waves. The study area covers the Lake Baikal region and adjacent territories characterized by high seismic activity. Here occurred several catastrophic earthquakes including the strongest one during the period of instrumental observations – the Middle Baikal’1959 earthquake. Recently here occurred the Kudarinsky earthquake on December 9, 2020 with mb=5.4. For more than twenty years the network of observations has been expanding, the equipment has been upgrading. A significant amount of seismo-logical material has been accumulated. Broadband data was processed by the receiver function method. The Moho and the lithosphere-asthenosphere boundaries for stations of the network are determined. Shear seismic wave attenuation characteristics are obtained and the possibility of energy classification of Baikal earthquakes by coda-waves total oscillations is shown.

Prediction of Wave Transmission Characteristics of Low-Crested Structures with Comprehensive Analysis of Machine Learning.

The adoption of low-crested and submerged structures (LCS) reduces the wave behind a structure, depending on the changes in the freeboard, and induces stable waves in the offshore. We aimed to estimate the wave transmission coefficient behind LCS structures to determine the feasible characteristics of wave mitigation. In addition, various empirical formulas based on regression analysis were proposed to quantitatively predict wave attenuation characteristics for field applications. However, inherent variability of wave attenuation causes the limitation of linear statistical approaches, such as linear regression analysis. Herein, to develop an optimization model for the hydrodynamic behavior of the LCS, we performed a comprehensive analysis of 10 types of machine learning models, which were compared and reviewed on the prediction accuracy with existing empirical formulas. We found that, among the 10 models, the gradient boosting model showed the highest prediction accuracy with MSE of 1.0 × 10−3, an index of agreement of 0.996, a scatter index of 0.065, and a correlation coefficient of 0.983, which indicates a performance improvement over the existing empirical formulas. In addition, based on a variable importance analysis using explainable artificial intelligence, we determined the significant importance of the input variable for the relative freeboard (RC/H0) and the relative freeboard to water depth ratio (RC/h), which confirms that the relative freeboard was the most dominant factor for influencing wave attenuation in the hydraulic behavior around the LCS. Thus, we concluded that the performance prediction method using a machine learning model can be applied to various predictive studies in the field of coastal engineering, deviating from existing empirical-based research.

Effect of enhanced coating layer on the bandgap characteristics and response of metaconcrete

Metaconcrete is made by partially or fully replacing natural coarse aggregates (NA) in normal concrete (NC) with engineered aggregates (EA). Normal engineered aggregate (NEA) is made by wrapping elastic coating outside spherical heavy core. It was found that mixing NEA in concrete could effectively mitigate stress wave propagation in metaconcrete structure owing to the local resonance of the heavy core of NEA. However, it also reduced the concrete material stiffness and strength because of the low modulus of soft coating that led to relatively large deformation of mortar matrix under loading. To address the issue of low interface stiffness while maintain the local vibration ability of NEA, new enhanced engineered aggregate (EEA) is proposed by placing an additional enhanced coating layer outside the soft coating of NEA. In this study, three types of EEA aggregates composed of three enhanced coating layer materials (i.e., epoxy resin, steel, ultra-high performance concrete UHPC) are considered and their configurations are designed via the software COMSOL. The spall behaviors of enhanced metaconcrete (EMC) mixed with EEA aggregates are examined though numerical simulations. 3D mesoscale models of EMC composed of mortar, randomly distributed natural aggregates and EEA aggregates are built via the software LS-DYNA. The distinction between the bandgap characteristics of NEA and EEA is studied. The effects of enhanced coating layer material on the bandgap of EEA and the performance of EMC with respect to energy absorption capacity, wave attenuation characteristics, and spall strength are studied. The results show that the existence of enhanced coating layer slightly affects the bandgap characteristics of engineered aggregate. Applying an additional stiffer coating layer to make the EEA aggregates can improve the spall strength of metaconcrete mixed with EEA aggregates while its ability in mitigating stress wave propagation and energy absorption is only slightly affected.