Additional Porosity Research Articles

ON THE INFLUENCE OF THE POROSITY OF FINE-GRAINED CONCRETES AND DRY BUILDING MIXTURES ON CONTACT ZONE FROST RESISTANCE

ObjectivesThis study was aimed at identifying the dependency of the frost resistance of the contact zone of fine-grained concretes (FGCs) obtained from dry building mixtures (DBMs) based on various Portland cements (PCs) with the content of various redispersable polymer powders (RPPs) from 0 to 3%.MethodThe research was based on 75 freeze-defrost cycles.ResultsAlthough the average dependency of adhesion with the base on additional porosity after 75 freeze-defrost cycles does not depend on the nature of NMV, adhesion is influenced by the cement type, the type and dosage of RPPs, as well as the nature of additional porosity. Since the content of organised volume of NMV in the form of VV has no effect on changes in adhesion with the concrete base following 75 freeze-defrost cycles, it is impractical to add more than 7% of NMV in the form of MS to the concrete mixture. The feasibility of using sulphate-resistant cement requires more research. The practical RPP dosage should be 1-2%. Some contradictions in conclusions on the volume of the introduced MS (by the strength criterion – at least 6%, by the criterion of frost resistance of the contact zone – no more than 7%) allows us to recommend the dosage of MS in RPP within 6-7% by volume for obtaining additional data on the MS effect on frost resistance.ConclusionThe dependency of compressive strength on additional porosity for FGCs without NMV and with NMV in the VV form after hardening during 28 days under normal conditions almost coincides with the known dependency of strength on porosity for cement stone; the maximum divergence of the values ???????? ????0 in the investigated range does not exceed 5%. The dependency of compressive strength on additional porosity for FGCs without NMV and with NMV in the MS form is similar to the known dependency of strength from porosity for cement stone; however, with increasing porosity, there is a slight decrease in the effect of porosity on strength. The dependency of compressive strength after 75 freeze-defrost cycles on additional porosity for FGC without NMV practically coincides with the previously obtained dependency of strength on porosity for cement stone; the maximum divergence of the values ???????? ????0 in the investigated range does not exceed 9%. For FGCs with NMV in the MC form, increasing porosity causes a slight decrease in the porosity effect on strength, and for FGCs with NMV in the VV form, the dependency has a quantitative and qualitative difference. The value of NMV in the VV form recommended for improving the frost resistance of FGCs by the strength criterion is at least 3%, MS – at least 6%. According to the criterion of the frost resistance of the contact zone and the strength of MS, the recommended dosage is 6-7%. It was not possible to disclose the direct impact of the VV volume on the frost resistance of the contact zone.

Multi-stage pore development in Ag foams by the reduction of Ag2O and CuO mixtures

Pore expansion in solid metals is typically driven by an entrapped gas phase, such that temperature directly determines both the pressure within the pores and the ability of the matrix to plastically deform. This approach fundamentally limits the total porosity, as all pores are active simultaneously, which quickly results in coalescence and percolation. The method introduced here converts dispersed oxide particles to a gaseous reactant using reduction, such that independent stages of pore formation and expansion can be achieved by using more than one oxide chemistry. This is demonstrated using silver and copper oxides distributed within a silver matrix. As the temperature is raised, the silver oxide reduces first and creates porosity. As the temperature is raised further, the copper oxide reduces and creates additional porosity. This allows the pore morphology and grain size to be uniquely controlled while still maintaining the simplicity and scalability of the process. The microstructural development is studied through a combination of isothermal annealing, optical dilatometry, and focused ion beam cross-sectioning, and implications and strategies for other alloy systems are discussed.

Composite porous carbon textile with deposited barium titanate nanospheres as wearable protection medium against toxic vapors

Barium titanate nanospheres (BTO-NPs) were deposited on carbon textile fibers, as a homogeneous coating (8 wt%; thickness 80–240 nm). The composite material/textile was thermally stable, porous, and water repellent. Its adsorption capacity against mustard gas surrogate vapors increased 17%, compared to those on separate carbon textiles and BTO-NPs, indicating a synergy of both components. The deposited nanospheres created an additional porosity in the coating and at the interface, which promoted adsorption of the CWA surrogate. The weight uptake was 313 mg/g, currently the highest reported under the conditions applied. Desorption tests showed a very strong retention of the adsorbed vapors. The CWA surrogate decomposed into various products and the extent of the catalytic activity of the composite textile markedly exceeded those of its components. This was linked to the beneficial effect of the interface. Upon air exposure, the exhausted textile could be reused as a protective medium.

Síntesis de Zeolitas ZSM-11 con Porosidad Jerarquizada

En este trabajo se propone la creación de porosidad adicional en zeolitas microporosas con estructura ZSM-11 mediante síntesis directa utilizando un surfactante catiónico (CTAB) como plantilla mesoporosa. Se investigó el efecto del tiempo de cristalización y la modificación del contenido de CTAB en la síntesis sobre la obtención de la estructura cristalina y la generación de mesoporosidad. Los sólidos obtenidos fueron caracterizados por Difracción de Rayos X (DRX), Isotermas de adsorción y desorción de nitrógeno, área superficial BET, Microscopia electrónica de barrido (SEM) y Espectroscopia de emisión atómica con plasma inductivamente acoplado (ICP- AES). Los resultados confirmaron que las zeolitas obtenidas poseen mesoporosidad en su estructura conservando la microporosidad intrínseca de la zeolita.

(Invited) Manufacturing and Characterization of Advanced High Energy Silicon/Graphite Electrodes

Next generation lithium-ion batteries (LIB) with high energy density and high power density have recently become of great interest for electric vehicle and portable devices. With the further upgrade of especially electric vehicles, the next generation LIB with high power and high energy density is urgently required. For this purpose, composite electrode consisting of commercially available graphite active material mixed with silicon nanoparticles is under current development. The main objectives are a significant increase of the practical capacity and energy density of commercial anodes, an overcome of the drawbacks of pure silicon due to large volume changes during electrochemical cycling, and the development of a technology suitable for mass production. In order to reduce the intrinsic mechanical stress of silicon/graphite electrodes and to improve the lithium-ion transport kinetic, free-standing electrode structures were generated by applying ultrafast industrial capable laser material processing. This advanced laser technology is demonstrated to be a flexible and powerful tool for pushing silicon/graphite (Si/C) composite anode materials beyond state of the art electrodes towards application. The electrochemical properties of cells with unstructured and structured electrodes were systematically analyzed by means of cyclic voltammetry, galvanostatic measurements, and electrochemical impedance spectroscopy. The increased active surface enables a significant improvement of lithium-ion diffusion kinetics. Furthermore, it is expected that the increased active surface will also provide additional artificial porosity for active material expansion, which in turn will reduce the mechanical stress within the electrodes during lithiation or delithiation. In this context, in-situ scanning electron microscopy (SEM) was performed in order to analyze the active material volume changes during charging and discharging. A main engineering challenge was to optimize the electrode architecture such as the pitch distance of free-standing structures regarding an enhanced electrochemical performance and a reduced material loss. Furthermore, an alumina (Al2O3) layer with a thickness of 5 nm, which acts as an artificial SEI, was coated on structured silicon/graphite electrodes by applying Atomic Layer Deposition (ALD). Cyclic voltammetry measurements were subsequently performed in order to investigate the fundamental properties of cells with structured and Al2O3- coated silicon/graphite electrodes. Galvanostatic measurements reveal that the cells with structured electrodes exhibit excellent electrochemical properties, i.e., a significantly improved capacity retention. ALD layers can contribute to further improvement of cycle stability and cell lifetime. In addition, advanced full cells with Lithium Nickel Manganese Cobalt Oxide NMC622 as cathode and Si/C as counter electrode were assembled and the electrochemical data will be presented.

Monitoring permeability potential of hot mix asphalt via binary aggregate packing principles correlated with Bailey ratios and porosity principles

Asphalt mix designs tend to optimise the load transfer via aggregate skeletons as main mechanism to provide rut resistance, often to the detriment of durability. Permeability, as a significant durability indicator, is more difficult to measure in the field than in the laboratory. Voids in the asphalt mix have a critical zone where an increase in voids is exponentially linked to permeability. This zone is where voids start to become increasingly interconnected. The aggregate grading envelope characteristics can provide an indication of the interconnectedness of the voids to enhance quality control. New rational Bailey Method Ratios (BMRs) were defined with contiguous aggregate fractions in the numerator and denominator. This allows also for porosity calculation using the Dominant Aggregate Size Range (DASR) method. The Binary Aggregate Packing (BAP) triangle porosity diagrams provide insight into the link between porosity and interconnected voids. The wall and the loosening effects create additional porosity (voids) with increased probability of interconnectedness. Clear threshold zones of interconnected voids can be determined with BAP coarse/fine mass ratios. The latter is the inverse of the rational BMRs. It allows for simple spreadsheet calculations of porosity and coarse/fine mass ratio as a screening tool for probable permeability via benchmark analysis. Reworked data sets demonstrated how the inverse of BMRs could show potential for interconnectedness of voids and, therefore, permeability propensity.

Porosity Design of Shaped Zeolites for Improved Catalyst Lifetime in the Methanol-to-Hydrocarbons Reaction

Additional porosity, such as meso- and macropores, was introduced in zeolite extrudates with the intention intuit of improving the effective diffusivity of the catalysts. The samples were characterized in depth by nitrogen adsorption-desorption, mercury intrusion porosimetry, ammonia temperature programmed desorption and adsorption of pyridine followed by infrared spectroscopy. The results revealed no significant change in the acidity but an increase of the pore volume. According to significant improvement in the effective diffusivity, the samples were tested in the methanol-to-hydrocarbons reaction. The catalytic stability was greatly enhanced with an increase in the pore volume, demonstrating a relation between effective diffusivity and resistance to deactivation by coke formation. Further experiments also revealed a higher toluene adsorption capacity and a raise in the breakthrough time over the most porous samples due to better accessibility of toluene molecules into the active sites of the zeolite.

Computational study on the effect of gasification reaction on pulverized coal MILD combustion diluted by N2 and CO2

The behavior of pulverized coal gasification reaction under MILD combustion regime will be significant, and then it affects pulverized coal combustion. This work performs a computational study on the effects of gasification reaction on pulverized coal MILD combustion with N2 and CO2 dilution. Results show that, regardless of at air or O2/CO2 atmospheres, the proportion of char consumed by gasification reaction exceeds 50%. The gasification reaction makes a decrease in flame temperature about 80 K at O2/CO2 and about 50 K at air. The delayed ignition time affected by the gasification reaction is 1.38 ms at air while 3.29 ms at O2/CO2 due the formation of CO. The presence of gasification reaction shortens the char burnout time at air and O2/CO2 atmospheres. The reactions of H2O and CO2 with char destroy the char surface structures and create additional porosity, which prompts the char burnout. The significant decrease in the NOx emission affected by gasification reaction at air and O2/CO2 atmospheres can be attributed to the enhancement of NO reburning and the suppression of fuel-NOx conversion, i.e., NH3 + O2 → NO + products.

Hierarchical‐Porous Ceramic Foams by a Combination of Replica and Freeze Technique

Open‐porous alumina foams with additional strut porosity are fabricated by a two‐step sponge‐replication based manufacturing process. As the first step, open cellular ceramic foams are prepared following the Schwarzwalder sponge replication technique. Therefore, organic foam templates are coated with different aqueous alumina slurries with a solid load between 20 and 40 vol% In a second step, an additional porosity is generated inside the foam struts by freezing of the foams at temperatures between −196 and −20 °C and subsequent sublimation drying. The hierarchical structure of both, cell pores and strut pores in the freeze‐dried material remains intact after drying, template removal, and sintering. Size, connectivity, and morphology of the strut pores strongly depend on the solid load of the alumina slurry and on the freezing temperature. Cellular structures with a strut porosity between 50% and 60% and a total porosity exceeding 90% are prepared, which show a compressive strength in between 0.4 to 0.6 MPa. Due to the additional strut porosity, the specific surface area of freeze‐dried replica foams increases from 70 cm2 g−1for conventionally prepared foams to 200 cm2 g−1for freeze‐dried foams, respectively.

Contact strength of C-S-H cement phase

The object of the study was the cement phase C-S-H – X-ray amorphous calcium hydrosilicates, obtained by steaming at 80°C together limestone and silica at different molar ratios CaO/SiO2 = 0.5; 1.0; 1.5. The contact strength of the C-S-H phase with additions of portlandite, silica and alumina zols, high-aluminate slag was estimated by hyper-pressing method with subsequent destruction. It was established that the contact strength of the cement phase increases in proportion to the specific pressing pressure, the age of samples and inversely the phase basicity reaching 12 MPa. It was evidenced that additives increase the contact strength of the C-S-H stone. The features of the phase formation during the hydration of calcium aluminates were considered. It was established that there is no negative effect of additional porosity on the strength of the stone, because the restructuring of calcium hydroaluminates takes place during hyper-pressing. The specific behavior of low-basic calcium aluminates in a mixture with the C-S-H phase was established in the case of using high-aluminate slag, which consists in additional formation Al(OH)3 gel during the hydration, that is provide an increase in the contact strength of the compositions.

Assessment of the Improvement of Effective Diffusivity over Technical Zeolite Bodies by Different Techniques

Technical zeolite bodies with additional porosity have been prepared with the intention to improve effective diffusivity. The latter has been assessed by three different techniques, combining a sim...

Bio-additive fuels from glycerol acetalization over metals-containing vanadium oxide nanotubes (MeVOx-NT in which, Me = Ni, Co, or Pt)

The biodiesel production has led to a drastic surplus of glycerol and catalytic conversion of glycerol into value-added products is of great industrial importance. Thus, the acetalization of glycerol with ketone or aldehydes allows the glycerol transformation into bio–additive fuels. In this work, metals-containing vanadium oxides nanotubes (MeVOx NT in which, Me = Co, Pt or Ni) have been synthesized with additional internal porosity and tested in the acetalization of glycerol with acetone (AG) for valuable biofuels production. The catalysts showed remarkable performances in the AG reaction. Furthermore, by variation of the composition, catalyst loading and temperature and using distinct substrates (butyraldehyde, furfuraldehyde and benzaldehyde), NiVOxNT is active, being very selective to solketal and reciclable for 4 times in the AG reaction. On the contrary, pure VOx NT easily deactivated due to the structure agent removal during the reaction, which promote the collapse of the tubular structure. The CoVOxNT and PtVOxNT catalysts did not exhibit such a stable structure and easily deactivated in the reaction due to leaching of the metals oxides during the AG.

Self-assembly porous metal-free electrocatalysts templated from sulfur for efficient oxygen reduction reaction

Acetylene black (AB) was exfoliated and functionalized through a single-pot method then be assembled to a novel porous carbon material by utilizing sulfur as both template and sulfur source. The defect-rich structures of the obtained AB play a critical role in providing more appropriate sites for sulfur atom doping. After a pyrolysis process in the presence of melamine as N doping agent, the sulfur template was decomposed and yielded the N,S-codoped porous carbon material with additional porosity. The synergistic effects between the defect-projecting and heteroatoms-doping boost the activity of electrocatalysts in terms of the enhanced oxygen reduction efficiency and optimized kinetic process, both are better than that of commercial Pt/C. And the improved reactivity between carbon atoms and heteroatoms as well as sulfur and nitrogen atoms greatly suppress the loss of active ingredient of the catalyst, the mechanism yields a striking long-term stability for the unique metal-free OAB@S-N electrocatalyst.

Cu- and Zr-based metal organic frameworks and their composites with graphene oxide for capture of acid gases at ambient temperature

Capture of acid gases (CO2 and H2S) by liquid solvent absorption is the common industrial practice, yet capture relying on solid adsorbents is increasingly gaining interest as potential alternative towards less energy-demanding operations. Herein, we developed and examined various metal organic frameworks (MOFs) bearing Cu- and Zr- metal clusters and their composites with graphene oxide (GO), and evaluated their performance for CO2 and H2S adsorption. Specifically, UiO-66, UiO-66-NH2, HKUST-1, and their GO composites were grown, subjected to structural, morphological, and textural characterization, and subsequently evaluated for their adsorption capacity and selectivity at ambient temperature. The crystallinity of the parent MOFs was preserved upon in-situ growth of the MOF/GO composites, while incorporation of GO yielded uniformly-shaped and well-dispersed MOF crystals resulting in enhanced sorption kinetics, and increased the pore volume compared to pure MOFs due to additional porosity formed in the interstitial spaces between the MOF crystallites and the GO flakes. To this extent, the interplay between additional porosity and pore functionalities in the competitive CO2 and N2 adsorption was investigated. UiO-66-NH2 exhibited enhanced CO2 capacity (3.07 mmol/g at 25 ⁰C and 4 bar) and the highest CO2/N2 selectivity (167 at 1 bar) among the tested MOFs, due to the presence of the amine functional groups in the organic linker that enhanced affinity with CO2. At increased pressures, the UiO-66-NH2/GO composite exhibited higher CO2 capacity compared to pure UiO-66-NH2, which is attributed to activation of the additional porosity between the MOF crystallites and the GO layers. HKUST-1/GO selectivity was also enhanced compared to HKUST-1 in all pressures tested. Under humid environment, the UiO-66 based structures were relatively stable in contrast to the HKUST-1 ones that underwent gradual degradation. These composites offer functionalization tunability due to the presence of both MOF and GO counterparts for targeted gas capture applications.

Design of cemented tungsten carbide and boride-containing shields for a fusion power plant

Results are reported on cemented tungsten carbide (cWC) and boride-containing composite materials for the task of shielding the centre column of a superconducting tokamak power plant. The shield is based on five concentric annular shells consisting of cWC and water layers of which the innermost cWC shield can be replaced with boride composites. Sample materials have been fabricated changing the parameters of porosity P, binder alloy fraction fbinder and boron weight fraction fboron. For the fabricated materials, and other hypothetical samples with chosen parameters, Monte Carlo studies are made of: (i) the power deposition into the superconducting core, (ii) the fast neutron and gamma fluxes and (iii) the attenuation coefficients through the shield for the deposited power and neutron and gamma fluxes. It is shown that conventional Co-based cWC binder alloy can be replaced with a Fe–Cr alloy (92 wt.% Fe, 8 wt.% Cr), which has lower activation than cobalt with minor changes in shield performance. Boride-based composite materials have been prepared and shown to give a significant reduction in power deposition and flux, when placed close to the superconducting core. A typical shield of cemented tungsten carbide with 10 wt.% of Fe–8Cr binder and 0.1% porosity has a power reduction half-length of 0.06 m. It is shown that the power deposition increases by 4.3% for every 1% additional porosity, and 1.7% for every 1 wt.% additional binder. Power deposition decreased by 26% for an initial 1 wt.% boron addition, but further increases in fboron showed only a marginal decrease. The dependences of power deposited in the core, the maximum neutron and gamma fluxes on the core surface, and the half attenuation distances through the shield have been fitted to within a fractional percentage error by analytic functions of the porosity, metallic binder alloy and boron weight fractions.

Concrete resistant to spalling made with recycled aggregate from sanitary ceramic wastes – The effect of moisture and porosity on destructive processes occurring in fire conditions

The paper describes a new model of the production of the concrete that is resistant to the conditions of a sudden temperature rise, which simulate a fire. Aluminum cement and aggregate obtained from the sanitary ceramic ware wastes were used for the production of the concrete. The composite was modified by the addition of the polypropylene fibers or by introducing additional porosity into the material. The purpose of the work was to produce a concrete, which would have optimal strength parameters despite the impact of a high temperature equal to 1000 °C. The paper presents the results of the research on the physical properties of the cementitious composites, as well as compressive strength before and after thermal loading. In addition, the microstructure of the heated concretes in various moisture states was investigated using a scanning electron microscope (SEM). On this basis, conclusions were drawn regarding the influence of destructive physical changes within the cement paste on the strength properties of the concretes; the beneficial characteristics of the ceramic aggregate in the aspect of the water vapor diffusion were pointed. In addition, the process of the cracks’ propagation in the structure of the cement matrix due to thermal load, and the diffusion of water vapor by the structure of the ceramic aggregate has been schematically modeled in the paper.

Catalytic Isomerization of Dihydroxyacetone to Lactic Acid and Alkyl Lactates over Hierarchical Zeolites Containing Tin

Hierarchical zeolites containing tin were obtained, characterized and used in a reaction of catalytic isomerization of dihydroxyacetone (DHA) to lactic acid and alkyl lactates. These catalysts are characterized by preserved crystallinity and primary microporosity with the simultaneous existence of secondary porosity regarding mesopores, which facilitates access of large molecules of reagents to active centers. Creation of additional porosity was confirmed by X-ray diffraction and low-temperature nitrogen adsorption/desorption studies. The reaction of dihydroxyacetone isomerization was conducted in different reaction media such as methanol, ethanol or water with the use of two heating methods: microwave radiation and conventional heating. The application of microwave radiation enabled to reduce the reaction time to 1 h and achieve dihydroxyacetone conversion of >90% and high yields of the desired reaction products.

Thermochemical sulphate reduction can improve carbonate petroleum reservoir quality

Interest in the creation of secondary pore spaces in petroleum reservoirs has increased because of a need to understand deeper and more complex reservoirs. The creation of new secondary porosity that enhances overall reservoir quality in deeply buried carbonate reservoirs is controversial and some recent studies have concluded it is not an important phenomenon. Here we present petrography, geochemistry, fluid inclusion data, and fluid-rock interaction reaction modeling results from Triassic Feixianguan Formation, Sichuan Basin, China, core samples and explore the relative importance of secondary porosity due to thermochemical sulphate reduction (TSR) during deep burial diagenesis. We find that new secondary pores result from the dissolution of anhydrite and possibly from dissolution of the matrix dolomite. Assuming porosity before TSR was 16% and the percentage of anhydrite was 6%, modelling shows that, due to TSR, 1.6% additional porosity was created that led to permeability increasing from 110 mD (range 72–168 mD within a 95% confidence interval) to 264 mD (range 162–432 mD within a 95% confidence interval). Secondary porosity results from the density differences between reactant anhydrite and product calcite, the addition of new water during TSR, and the generation of acidity during the reaction of new H2S with the siderite component in pre-existing dolomite in the reservoir. Fluid pressure was high during TSR, and approached lithostatic pressure in some samples; this transient overpressure may have led to the maintenance of porosity due to the inhibition of compactional processes. An additional 1.6% porosity is significant for reserve calculations, especially considering that it occurs in conjunction with elevated permeability that results in faster flow rates to the production wells.

Helium interactions with alumina formed by atomic layer deposition show potential for mitigating problems with excess helium in spent nuclear fuel

Helium gas accumulation from alpha decay during extended storage of spent fuel has potential to compromise the structural integrity the fuel. Here we report results obtained with surrogate nickel particles which suggest that alumina formed by atomic layer deposition can serve as a low volume-fraction, uniformly-distributed phase for retention of helium generated in fuel particles such as uranium oxide. Thin alumina layers may also form transport paths for helium in the fuel rod, which would otherwise be impermeable. Micron-scale nickel particles, representative of uranium oxide particles in their low helium solubility and compatibility with the alumina synthesis process, were homogeneously coated with alumina approximately 3–20 nm by particle atomic layer deposition (ALD) using a fluidized bed reactor. Particles were then loaded with helium at 800 °C in a tube furnace. Subsequent helium spectroscopy measurements showed that the alumina phase, or more likely a related nickel/alumina interface structure, retains helium at a density of at least 1017 atoms/cm3. High resolution transmission electron microscopy revealed that the thermal treatment increased the alumina thickness and generated additional porosity. Results from Monte Carlo simulations on amorphous alumina predict the helium retention concentration at room temperature could reach 1021 atoms/cm3 at 400 MPa, a pressure predicted by others to be developed in uranium oxide without an alumina secondary phase. This concentration is sufficient to eliminate bubble formation in the nuclear fuel for long-term storage scenarios, for example. Measurements by others of the diffusion coefficient in polycrystalline alumina indicate values several orders of magnitude higher than in uranium oxide, which then can also allow for helium transport out of the spent fuel.

Towards assessing cortical bone porosity using low-frequency quantitative acoustics: A phantom-based study.

PurposeCortical porosity is a key characteristic governing the structural properties and mechanical behaviour of bone, and its quantification is therefore critical for understanding and monitoring the development of various bone pathologies such as osteoporosis. Axial transmission quantitative acoustics has shown to be a promising technique for assessing bone health in a fast, non-invasive, and radiation-free manner. One major hurdle in bringing this approach to clinical application is the entanglement of the effects of individual characteristics (e.g. geometry, porosity, anisotropy etc.) on the measured wave propagation. In order to address this entanglement problem, we therefore propose a systematic bottom-up approach, in which only one bone property is varied, before addressing interaction effects. This work therefore investigated the sensitivity of low-frequency quantitative acoustics to changes in porosity as well as individual pore characteristics using specifically designed cortical bone phantoms.Materials and methods14 bone phantoms were designed with varying pore size, axial-, and radial pore number, resulting in porosities (bone volume fraction) between 0% and 15%, similar to porosity values found in human cortical bone. All phantoms were manufactured using laser sintering, measured using axial-transmission acoustics and analysed using a full-wave approach. Experimental results were compared to theoretical predictions based on a modified Timoshenko theory.ResultsA clear dependence of phase velocity on frequency and porosity produced by increasing pore size or radial pore number was demonstrated, with the velocity decreasing by between 2–5 m/s per percent of additional porosity, which corresponds to -0.5% to -1.0% of wave speed. While the change in phase velocity due to axial pore number was consistent with the results due to pore size and radial pore number, the relative uncertainties for the estimates were too high to draw any conclusions for this parameter.ConclusionsThis work has shown the capability of low-frequency quantitative acoustics to reflect changes in porosity and individual pore characteristics and demonstrated that additive manufacturing is an appropriate method that allows the influence of individual bone properties on the wave propagation to be systematically assessed. The results of this work opens perspectives for the efficient development of a multi-frequency, multi-mode approach to screen, diagnose, and monitor bone pathologies in individuals.