Ultrasonic Propagation Velocity Research Articles

Influência da variabilidade da temperatura de exposição na degradação do concreto em função da resistência à compressão e velocidade de propagação de onda ultrassônica

Abstract This study evaluated the influence of heating temperature variability on the degradation level of concrete by varying the exposure temperatures (200°C, 450°C, and 800°C) and concrete design strength (C25 and C40). The concretes were submitted to ultrasound tests (before and after heating) and then were ruptured by axial compression. After rupture, samples were taken from the fracture section of the specimens for microstructural analysis by scanning electron microscope (SEM), and molecular analysis by Raman spectroscopy. The results showed that the residual strength of the concrete can change significantly (values differing by more than 100%) with temperature variability in the oven. There were physicochemical changes in the concrete constituents. The variations in Raman spectra and morphological changes (SEM images) allowed to analyze the variation in the level of degradation of concrete after exposure to fire, at the same firing step, due to temperature variation in the ovens, being compatible with the results of compressive strength and ultrasonic wave propagation velocity (UPV). Thus, the study highlights the need for adequate mapping of the heat in the oven and monitoring of the temperature of specimens in studies of concrete at high temperatures.

Development of sweep frequency ultrasonic interferometer for high precision velocity measurement in liquids.

An ultrasonic interferometer with variable separation between the transducer and reflector is widely used for the measurement of ultrasonic propagation velocity in liquids. The inherent limitation of such an interferometer is due to the mechanical movement of its reflector for ultrasonic wavelength measurement in a liquid medium. It is observed that the ultrasonic velocity measurement precision is adversely affected at higher frequencies compared to lower ones. For instance, in our experimentation, a standard deviation of ±21.5m/s (±1.43%) was obtained for velocity measurement at 1.84MHz with the consideration of two consecutive maxima, which increases drastically to ±76.8m/s (±5.12%) at 9.4MHz. These measurements can significantly be improved by considering many maxima and averaging for wavelength estimation. However, it still requires design attention and improvement, particularly for higher frequencies. In this article, a sweep-frequency based ultrasonic interferometer design with a fixed separation for liquid characterization is proposed and described. This technique overcomes the limitations of mechanical movement systems and also provides a better and uniform precision for lower as well as higher frequencies. The functionality of the developed sweep frequency method was tested in water, carbon tetrachloride, ethylene glycol, and glycerol, which shows good agreement with literature values. The velocity measurement in double distilled water by the developed technique at 1Hz sweep resolution has shown an improved standard deviation of ±0.74m/s (±0.05%) at 9.4MHz.

Evaluation of the Uniaxial Compressive Strength of Gneiss from Southern Togo from Non-Destructive Tests

The mechanical and physical characteristics of rocks hold significant importance across various realms of research and engineering, particularly in the field of Civil Engineering. The utilization of rocks as construction materials hinges on several of their mechanical traits (Los Angeles, Micro Deval under water presence, Young's Modulus, Compression Strength) as well as physical attributes (homogeneity, porosity, etc.). Tests for determining certain of these characteristics are expensive, challenging, and time-consuming. Among these attributes, mention can be made of determining compression strength, which necessitates substantial equipment for proper sample preparation. This renders the process very costly, laborious, and leads to the complete destruction of samples during experimental measurements. Our objective in this study is to assess the uniaxial compression strength of gneiss from southern Togo using non-destructive testing. This would help mitigate the relatively high costs associated with this test. To address this issue, the development of new methods for determining this test using non-destructive testing approaches is necessary. Among the most commonly used reference techniques for characterizing materials and determining their physical and mechanical properties are non-destructive evaluation techniques based on ultrasonic wave propagation and rebound hammer testing. The adopted methodological approach involves the collection of rock samples (amphibole and biotite gneiss) from 33 sites in southern Togo, their proper sampling, and the execution of various tests on the obtained samples. The obtained results have facilitated the examination of several approaches, notably the ANFIS model (Adaptive Neuro-Fuzzy Inference System) and the MLR model (Multiple Linear Regression), for predicting the uniaxial compression strength value based on the sclerometer index and the ultrasonic wave propagation velocity (in parallel or perpendicular orientation to the foliations). It emerges from the ANFIS model, combining ultrasonic waves in the perpendicular orientation to the foliations and the sclerometer index, that the uniaxial compression strength can be predicted with an R² of 0.9884, an RMSE of 2.9271, a MAPE of 1.160, and a VAF of 98.83. In comparison, the MLR model yields an R² of 0.9832, an RMSE of 3.686, a MAPE of 1.402, and a VAF of 98.22. The derived ANFIS models can be utilized to estimate the uniaxial compression strength of gneiss in Togo and beyond. Keywords: Gneiss, Non-destructive Testing, Sclerometer Index, Ultrasonic, Compression Strength.

Self-healing properties of cement-based materials in different matrix based on microbial mineralization coupled with bimetallic hydroxide

Self-healing properties of cement-based materials in different matrix based on microbial mineralization coupled with bimetallic hydroxide were systematically studied. Firstly, the self-healing macroscopic properties of cement-based materials in different matrix were studied. The area repair rate of cement paste early crack was better than that of mortar and concrete, which showed that self-repairing agent also had excellent repair properties in the early stage. With the extension of the curing time, the repair effect was significantly enhanced; The repair effect was basically the same when the curing time was 28 d. After curing for 28 d, the resistance of the three matrix to water permeability were basically restored to intact. At each curing time, the ultrasonic propagation velocity in concrete was the largest, and that in cement paste was the smallest. Secondly, the composition and microstructure of the mineralized products were analyzed by XRD, SEM, EDS and TGA. Additionally, the pore size of the product was also tested. The characteristic peaks of XRD were consistent with the products of the target design, corresponding to the formation of calcium-aluminum bimetallic hydroxide and calcium carbonate. Mineralized products were mainly composed of two forms of inorganic minerals, one was bimetallic hydroxide with lamellar structure, and the other was CaCO3; Moreover, the quantity of calcite was much higher than that of bimetallic hydroxide. Finally, the principle that ultrasonic velocity differently after repair in different matrix was explained, and the mechanism of microbial mineralization coupled with bimetallic hydroxide to repair crack was revealed. The bimetallic hydroxide could fix the hydroxide ion, chloride ion and sulfate ion, which not only improved the repair efficiency, but also reduced the corrosion.

Changes in the Vickers hardness, wettability, structural and mechanical properties of the «shielding composite» under the exposure to cosmic radiation

The article presents the results of the study of the structure and surface of the «Shielding composite» (polymer composite for radiation shielding), which was in space on the Russian segment of the ISS for 225 days. The research was conducted as part of the space experiment “Shielding Composite” on the Russian segment of the ISS in 2022. The polymer composite was used to make the container that was installed in the cosmonauts’ cabin for the entire duration of the orbital flight. Being in space resulted in a slight decrease in the microhardness of the outer surface, but did not affect the deeper layers or the inner structure of the composite: microhardness of the outer surface decreased by 0.19 HV (4.5 %); microhardness of the inner surface increased by 0.79 HV (18.6 %); cross section remained unchanged. The results of ultrasound scanning of the upper cap of the container showed a slight decrease in the ultrasonic wave propagation velocity (by 4 %) and the modulus of elasticity of the composite (by 9 %) after space tests of the composite. There is an insignificant decrease (up to 5 %) in free surface energy of the composite after being in space for 225 days. Water wetting contact angle of the composite increased from 100.98 ± 2.60° to 106.85 ± 14.28° and diiodo-methane wetting contact angle increased from 57.50 ± 8.33° to 59.55 ± 7.22° after cosmic exposure.

Influence of moisture on ultrasonic propagation, acoustic emission activity, and failure mechanism in concrete media

Free water in a concrete medium significantly influences its bearing capacity and failure mechanism. In this study, the mechanical properties and failure mechanism in concrete specimens with different moisture contents were investigated with the objective of enhancing the safety of concrete structures. Uniaxial compression tests were employed to study bearing capacity, ultrasonic propagation, acoustic emission activity and failure mechanism of concrete specimens with moisture contents of 0%, 2%, 4%, and 5.5%. The results implied that the crack initiation stress and compressive strength of concrete first increased and then decreased with the increase in moisture content, and the elastic modulus and Poisson’ s ratio first decreased and then increased. The inflection points were observed in the fitting curves for moisture contents within 1.15–1.65%. With the increase in the moisture in the concrete specimens, the ultrasonic propagation velocity in the material increased, the acoustic emission activity decreased, and the proportion of high-frequency acoustic emission signals decreased. The acoustic emission activity in the concrete specimens was observed predominantly in the failure stage under the influence of uniaxial stress. Based on the moment tensor inversion of acoustic emission, the proportion of shear damage in the failure process of concrete increased with the increase in moisture content. The failure mechanism was analyzed by obtaining the ISO and DC values of acoustic emission events, the moment tensor T–k diagram, and the P–T diagram. The geometric orientation of the acoustic emission events was consistent with the macroscopic fracture mode of the specimens. The ultrasonic propagation, acoustic emission characteristics and the deterioration mechanism of bearing capacity in water-saturated concrete were analyzed. The findings of this study can be applied in health monitoring and for the safe operation of concrete structures in water environments.

The use of inorganic ferrous–ferric oxide nanoparticles to improve fresh and durability properties of foamed concrete

Efforts to modify cement-based mixtures have continuously engrossed the interest of academics. Favourable impacts of nanoparticles, for instance, fine particle size and great reactivity, have made them be utilized in concrete. Foamed concrete (FC) is immensely porous, and its properties diminish with an increase in the number of pores. To enhance its properties, the FC matrix could be attuned by integrating numerous nanoparticles. The influence of ferrous–ferric oxide nanoparticles (FFO-NP) in FC was not discovered previously in the present body of knowledge. Thus, there is some uncertainty contemplating the mechanism to which extent the FFO-NP can affect the durability properties of FC. Hence, this study focuses on utilizing FFO-NP in the FC matrix. FC specimens with a density of 1000 kg/m3 were cast and tested. The objective was to assess the influence of different FFO-NP weight fractions (0.10%, 0.15%, 0.20%, 0.25%, 0.30%, and 0.35%) on durability properties such as drying shrinkage, porosity, water absorption and ultrasonic wave propagation velocity of FC. The results implied that the presence of a 0.25% weight fraction of FFO-NP in FC facilitates optimal water absorption, porosity, ultrasonic pulse velocity and drying shrinkage of FC. The presence of FFO-NP alters the microstructural of FC from loose needle-like into a dense cohesive microstructure of the cementitious composite. Besides, FFO-NP augments the FC matrix by filling the voids, microcracks, and spaces within the structure. Further than the ideal weight fraction of FFO-NP addition, the accretion of the FFO-NP was found, which caused a decline in durability properties.

IMPACT OF HIGH TEMPERATURE ON THE PROPAGATION SPEED OF ULTRASONIC WAVES IN STRONG ROCK FORMATIONS

Purpose: The purpose of the research is to establish the relationship between the velocity of ultrasonic waves in Lesnik, Maslav granites, Bukinsky gabbro, and Kateryniv labradorite at temperatures up to 800 degrees. Methods: In this study, samples of natural stone from the following rocks were heated: Maslav granite, Lesnik granite, Kateryniv labradorite, and Bukinsky gabbro. The samples were made in the form of cubes with a side size of 15×15 cm. One side of the sample was polished and the other sides were sawn. Measurements of ultrasonic wave propagation were made on the polished side. The samples were heated to temperatures of 200, 400, 600, and 800 degrees Celsius. Three cubes were taken for each temperature. Before heating, the velocity of ultrasonic waves in the samples of natural stone was measured using a handle with two piezoelectric sensors with a base of 120 mm. The ultrasonic wave was measured using a UK-14PM device. The velocity of ultrasonic wave propagation in the stone samples after heating was also measured. The velocity of ultrasonic wave propagation was calculated from the time it takes the ultrasonic wave to pass between the sensors. Results: In this research, the authors consider the effect of high temperature on the velocity of ultrasonic waves in granites, gabbro, and labradorite. The article provides an overview of the main factors that affect the velocity of ultrasonic wave propagation in natural stone. The results of studies conducted to investigate the effect of high temperature on this velocity in strong rocks are considered. The relationship between the velocity of ultrasonic wave propagation in Lesnik, Maslav granites, Bukinsky gabbro, and Kateryniv labradorite at temperatures up to 800 degrees has been established. Lesnik granite has the least loss of ultrasonic wave velocity upon heating, while Maslav granite has the greatest loss. When comparing labradorite and gabbro, labradorite has the least loss of ultrasonic wave velocity upon heating. Scientific novelty: For the first time, the dependence of the velocity of ultrasonic wave propagation in Lesnik, Maslav granites, Bukinsky gabbro, and Kateryniv labradorite at temperatures up to 800 degrees from the heating temperature has been obtained. Practical significance: Based on the obtained values, it is possible to assess the strength of natural stone after fires using a non-destructive control method. Keywords: high temperature, ultrasonic wave, natural stone, rock-forming minerals, color.

Measurement of Ultrasound Propagation Velocity in Liquids Using an FPGA Module

The design and development of an ultrasonic device for the measurement of ultrasonic propagation velocity in liquids based on Field Programmable Gate Array (FPGA) architecture is described. The device was implemented using a DE0-Nano-SoC Development Kit FPGA development module, a 2x16 LCD Display, a 2-channel quadrature output optical encoder with push button, two ultrasonic transducers and an external module for interfacing with the transducers containing the circuits corresponding to the transmitter, receiver and amplifier. For the development, the Altera Integrated Development Environment (IDE) software called Quartus II was used, which allows the logical design and supports different HDL hardware description languages, such as Verilog and VHLD. Although the device was calibrated to measure the acoustic velocity of water in the range of 35°C to 40°C, due to its design characteristics it is feasible to extend its application to measure acoustic velocity in different liquids, delimiting the operation intervals. The device acquires 100 readings per second, calculates the average with polynomial adjustment and displays the value of the ultrasonic propagation velocity in the fluid with a resolution of 0.01 [m/s] with a refresh rate of one second.

Multi-objective optimization to evaluate the compressive strength of concrete by combining non-destructive techniques

The compressive strength of concrete is one of the most important mechanical parameters in the evaluation of the mechanical performance of reinforced concrete structures. The recent methodology for the evaluation of the mechanical strength of concrete of an existing structure combines non-destructive testing (NDT) measurements, such as rebound measurement and ultrasonic wave propagation velocity measurement, with destructive measurements (sampling) in order to develop a conversion model, between mechanical strength and non-destructive measurements. The conversion model is then used to estimate the local value of the resistance at each location of the non-destructive measurements and thus to represent the spatial variability. The goal of this study is to propose a new methodology based on multi-objective optimization to predict the compressive strength of concrete and its variability based on NDT measurements. To this end, a large experimental and synthetic database of destructive and non-destructive tests was used. The conclusions drawn from the synthetic data will be compared with the results obtained on the real database in order to test the potential of the proposed methodology. This study shows the principle of the methodology and the first results of its effectiveness in predicting compressive strength and its variability.

Thermo-chemo-mechanical characterization, modeling, and analysis of hydration of calcium-sulfoaluminate cement paste

The reaction kinetic of a commercial calcium sulfoaluminate (CSA) cement was characterized by heat flow calorimetry. Distinct behavior is observed whether tartaric acid is added as retarding agent or not. Employing the so-obtained calorimetric data, heat of hydration and chemical affinity of the investigated binder mixture was determined. Furthermore, continuous ultrasonic propagation velocity measurement gave access to the stiffness gain of paste samples. However, the ultrasonic test setup is characterized by a non-constant temperature history (temperature rise and fall). Modeling the temperature history and the history of the degree of hydration with a thermo-chemical analysis scheme, the intrinsic material function of the stiffness evolution of the investigated hydrating CSA paste was obtained. Furthermore, the robustness of the thermo-chemical analysis scheme was demonstrated by the comparison of the measured with the simulated temperature evolution. The versatility of the approach may contribute to a systematic assessment and optimization of the heat/mechanical evolution of CSA binder systems under various geometric, temporal, and thermal boundary condition.

Using of the Ultrasonic Method for Alkali-Silica Reaction Detection in the Cement Mortar

The alkali–silica reaction (ASR) causes internal corrosion of concrete. The aim of this work is to verify the possibility of ultrasonic method in detection of concrete internal structure changes, which were initiated by the alkali-silica reaction. For this purpose, we prepared samples that contained aggregates of two types, namely one with 98% of SiO2 content and one with a greywacke. The dependence of ultrasonic impulse propagation velocity on the changes in the structure of mortars containing aggregates from these rocks was researched. The results of this work are not unambiguous yet and therefore it is necessary to carry out more extensive investigation with using of other methods that will allow to examine changes in the internal structure of composites more detailed.

The effects of an historical fire on a porous calcarenite from an industrial-archaeological building in the south of Italy

The effects of an historical fire were studied on a porous calcarenite coming from an historic building located in Southern Italy. Changes of material properties were investigated on the masonry blocks affected by fire in comparison with the sound stone. They were also compared with thermally induced degradation under controlled heating in laboratory conditions.The stone was affected by a pronounced aesthetical damage consisting of gray and red discoloring. This was the effect of mineralogical-chemical phase transitions, which were detected by diffractometric and thermal analyses. The transformation of goethite to hematite accounted for changes from the original pale yellow color to red. Gray discoloring was found related to burning of organic matter and formation of magnetite. Damage on the stone microstructure was detected by SEM in the form of micro-cracks. It was also investigated through non-destructive ultrasonic propagation velocity tests, which recorded velocity decreases between 6% and 26%. Microfissuring left almost unchanged the bulk density and porosity measured by buoyancy and saturation techniques, as well as the mechanical properties. The latter were assessed by uniaxial compressive tests. A combined experimental protocol, including colorimetry, non-destructive testing and mechanical testing was used to compare the samples conditioned at high temperature in a laboratory environment with those affected by the real fire. The results allowed to estimate that the maximum temperatures within the stone during fire were under 600 °C, up to 300 °C at a depth of about 8 cm.High porosity of the stone accounts for a limited stone damage at microstructural level and consequent low effects on physical-mechanical properties. On the contrary, in the presence of macrocracking due to the thermal shock experienced by the stone in some areas during fire, an UPV decrease of approximately 40% and significant strength reductions between 46 and 55% were found.

Characterization and Analysis of the Carbonation Process of a Lime Mortar Obtained from Phosphogypsum Waste.

This work addresses the reuse of waste products as a raw material for lime putties, which are one of the components of mortar. 1:3 Lime/sand mortars very similar to conventional construction mortars were prepared using a lime putty obtained from the treatment of phosphogypsum with sodium hydroxide. The physical, rheological and mechanical properties of this phosphogypsum-derived mortar have been studied, as well as the mineralogical composition, microstructure by scanning electron microscope (SEM) and curing process by monitoring carbonation and ultrasonic propagation velocity. Considering the negative influence of sulphates on the hardened material, the behaviour of the material after sulphates precipitation by adding barium sulphate was additionally tested. Carbonation progressed from the outside to the inside of the specimen through the porous system by Liesegang rings patterns for mortars with soluble sulphates, while the carbonation with precipitated sulphates was controlled by diffusion-precipitation. Overall, the negative influence of low-sulphate contents on the mechanical properties of mortars was verified. It must be highlighted the importance of their precipitation to obtain adequate performance.

Study of positional isomerism in N-propyl and Iso-propyl alcohol using ultrasonic technique

In the present work, positional Isomerism is studied in the binary mixtures of n-propyl alcohol and Iso-propyl alcohol in nitrobenzene as the common solvent. Ultrasonic velocity and attenuation measurements using pulse–echo technique operated at 10 MHz have been taken at various concentrations of both alcohols in nitrobenzene, from 283.15K - 293.15K. It is observed that both the systems exhibit critical nature and show non-linear variation both in ultrasonic velocity of propagation and attenuation. Ultrasonic attenuation at lower concentrations of n-propyl alcohol in nitrobenzene reveals the dominant structural relaxation as compared to that of Iso-propyl alcohol in nitrobenzene.

Ultrasonic testing of concrete hardening in pile foundations

This article discusses the ultrasonic method for monitoring the strength of concrete in piles. Geotechnical conditions of the city territory are indicated. The conditions of hardening of the concrete mixture in the pile shaft and the normal conditions of hardening of concrete samples are described. A detailed description of the control technique is given. The dependence of the ultrasonic wave propagation velocity on the age of concrete in piles and concrete samples is established. Based on the results of the work, it was concluded that it is possible to control the strength of concrete in-situ.

Impact Resistance Behavior of Reinforced Concrete Beams Deteriorated due to Repeated Freezing and Thawing

Many existing reinforced concrete (RC) structures constructed more than 50 years ago now require maintenance. This is especially true in cold, snowy regions where significant frost damage deterioration of RC structures becomes a severe problem. In this study, falling-weight impact tests were performed to investigate the impact resistance behavior of RC beams degraded by frost damage. An RC beam was subjected to approximately 900 freeze-thaw cycles to emulate the frost damage before the execution of the impact test. The surface of the beam was remarkably scaled, and its coarse aggregate was exposed. The degree of deterioration was evaluated by the distribution of ultrasonic propagation velocity. The following conclusions were drawn. (1) The ultrasonic propagation velocity of RC beams was significantly reduced following 872 freeze-thaw cycles. At the upper edge of the RC beam, the ultrasonic wave propagation velocity decreased from 4,000 m/s to 1,500 m/s in some parts. This corresponds to a relative dynamic elastic modulus of approximately 14%. (2) The residual deflection of RC beams with frost damage increased at most by 20% compared with beams without frost damage. The increase in residual deflection was primarily related to the peeling of concrete at the collision site and the opening of multiple bending cracks. (3) According to the existing residual deflection calculation formula, an increase of 20% in the residual deflection corresponds to a decrease of about 17% in the bending capacity of the RC beam. When the relationship between the degree of frost damage deterioration and the impact resistance of RC structures is defined, existing structures subjected to accidental impact force from rockfalls are safer and can be maintained more efficiently.

Исследование случаев «аномального» затухания ультразвуковых колебаний в заготовках из никелевых жаропрочных сплавов

An ultrasonic non-destructive testing has found out a new phenomenon in several stamped forgings made from heat-resistant nickel alloys (Ni-superalloys) of two grades: local attenuation of the bottom echo signal amplitude, when the workpiece surface had large (over 20 mm) randomly located zones with significant (up to 1.5%) fluctuations of the longitudinal ultrasonic wave propagation velocity. On top of that, there were no various grain sizes or coarse-grained structures that usually lead to a an increase of a rate of ultrasonic attenuation in such alloys, and which triggers off a bottom echo signal amplitude attenuation. The Article states the studies carried out to explain the tangible reasons of the detected macroinhomogeneity of the velocity, and how it associated with a bottom signal amplitude attenuation.

Continuous Wave Ultrasonic Interferometers with Relatively Higher Excitation are Inappropriate for Liquid Characterization

Ultrasonic velocity is an important property for various physicochemical investigations in the liquids. The continuous wave ultrasonic interferometers are widely used as a cost-effective instrument for the estimation of ultrasonic propagation velocity. One of the critical aspects of this instrument is the level of radio frequency excitation supplied to piezoelectric transducer, which can cause heating of the sample. The error in the ultrasonic velocity measurement due to heating by the ultrasonic interferometer is described. In this article, the distilled water was used as experimental liquid to study the heating effect. Firstly, the ultrasonic transducer has been used to generate ultrasound in the sample and was calibrated for its radiation conductance by using primary radiation force balance facility of the laboratory. Primary calibration of the ultrasonic transducer in a commercially available system used in the liquid cell showed 68 mW power for excitation level. In a laboratory interferometer designed for low-power operation in the same test cell, the measured power was only 85 µW. In order to study the heating effect, the ultrasonic velocity was measured with both the systems without controlling the temperature of liquid cell. The measurements by commercial system showed significant deviation (5.6 ms−1) in ultrasonic velocity as compared to that measured under low power excitation, which remains almost undeviated. The Marczak equation was used to calculate the deviation in velocity due to ultrasound heating.

Propagation characteristics of ultrasonic P-wave velocity in artificial jointed coal briquettes

AbstractAbundant engineering practice shows that coal and rock dynamic disasters often occur in fault zones; hence, the detection of faults in coal mines is important. As an essential branch of seismic tomographic application, research shows that ultrasonic P-wave velocity can detect mine faults and provide technical support for dynamic disaster prewarning systems. Traditional P-wave testing mostly takes rock or raw coal as the research object, which has some shortcomings in controllability, homogeneity and comparability. This paper compares the difference in ultrasonic P-wave propagation velocity in jointless and jointed briquettes through laboratory research, focuses on the effect of macro-joints on P-wave velocity and makes a preliminary theoretical analysis. The results show that: (i) the three-dimensional P-wave velocity throughout a jointless briquette specimen is similar, which reflects the high homogeneity of this medium and avoids the influence of the random distribution of primary bedding, joints and structural planes; (ii) the P-wave velocity in jointless and jointed briquettes is positively correlated with density and forming pressure, and is negatively correlated with the angle between the ultrasonic wave and the joint surface in a sample and (iii) when the P-wave encounters the macroscopic joint surface, it may reflect and refract, changing the propagation direction and inducing wave mode conversion. This study provides the necessary technical support and a theoretical guide to optimise acoustic property analysis of coal and rock as well as a field application for seismic tomography technology.