In this paper we discuss the test results for concretes containing various amounts of ggbs as compared to concretes made with Portland cement. The main objective of these tests is to evaluate the influence of varying air content in such mixtures on the structure and frost resistance of concrete. The authors suggest that the approach presented here allows for a safe design of concrete mixtures in terms of their frost resistance.

The results indicate that concrete can be resistant to surface scaling even at the W/C ratio markedly higher than 0.45. Increased addition of ggbs leads to a decrease in concrete resistance to surface scaling. Proper air entrainment is the fundamental factor for frost-resistant concrete, and the air void system has to be assessed (micropore content A₃₀₀, spacing factor L). The addition of ggbs increases pore diameters, thus, to obtain the appropriate air pore spacing factor, micropore quantities introduced have to be increased.

At thermal junctions of aluminium alloy castings and at points where risering proves to be difficult there appear internal or external

shrinkages, which are both functionally and aesthetically inadmissible. Applying the Probat Fluss Mikro 100 agent, which is based on

nano-oxides of aluminium, results in the appearance of a large amount of fine microscopic pores, which compensate for the shrinking of

metal. Experimental tests with gravity die casting of AlSi8Cu3 and AlSi10Mg alloys have confirmed that the effect of the agent can be of

advantage in foundry practice, leading to the production of castings without local concentrations of defects and without the appearance of

shrinkages and macroscopic gas pores. Also, beneficial effect on the mechanical properties of the metal has been observed.

Molecular motors are nature’s nanomachines, and are the essential agents of movement that are an integral part of many living organisms. The supramolecular machine, called the nuclear pore complex (NPC), controls the transport of all cellular material between the cytoplasm and the nucleus that occurs naturally in all biological cells. In the presence of appropriate chemical stimuli, the NPC opens or closes, like a gating mechanism, and permits the flow of material into and out of the nucleus. As a first step in understanding the design characteristics of the NPC, nanoscale studies were conducted to understand the transport characteristics of an idealized NPC model using CFD analysis, discrete element transport and coupled fluid-solid analysis. Results of pressure and velocity profiles obtained from the models indicate that the fluid density, flexibility of walls and the geometry of the flow passage are important in the design of NPC based nano- and micro-motors.

In the study we have focused on the distribution of several metals (Cr, As, Pb) and anions (Cr, NO3-) and their partition between pore (interstitial) waters and sediments sampled at three stations at the Dobczyce Reservoir which supplies the drinking water to inhabitants from the city of Kraków and its agglomeration. The results show considerable increase in concentrations of Pb and As in pore water samples, when compared to the bottom waters. Meaningful alternations in concentration were observed in case of pore water samples (Pb, As) and sediments (Cr, Pb, As), coming from three stations and their lateral sections. The possible relations between this phenomenon and the sediment characteristic as well as the Fe and Ca content, has been studied. Some comments on the seasonal variations of anion contents in water and pore water samples, are also provided. It was found that nitrates and sulphates show considerable variations.

Kaolin-based geopolymers are alternatives for producing high-strength ceramics for construction materials. Creating high-performing kaolin ceramics utilizing the regular technique requires a high handling temperature (higher than 1200°C). Thus, the structure and properties such as pore size and distribution are affected at higher sintering temperatures. Along these lines, information with respect to the sintering system and related pore structure is essential for advancing the properties of the previously mentioned materials. This study investigated the microstructure and the density of a kaolin-based geopolymer at various sintering temperatures. The unsintered sample has the highest density of 1610 kg/cm3, while the samples sintered at 1100°C haves the lowest density of 1203 kg/cm3. The result also shows that increasing the sintering temperature to 1100°C resulted in increasing the water absorption of the kaolin-based geopolymer ceramic.

The study aims to estimate metal foam microstructure parameters for the maximum sound absorption coefficient (SAC) in the specified frequency band to obtain optimum metal foam fabrication. Lu’s theory model is utilised to calculate the SAC of metallic foams that refers to three morphological parameters: porosity, pore size, and pore opening. After Lu model validation, particle swarm optimisation (PSO) is used to optimise the parameters. The optimum values are obtained at frequencies 250 to 8000 Hz, porosity of 50 to 95%, a pore size of 0.1 to 4.5 mm, and pore opening of 0.07 to 0.98 mm. The results revealed that at frequencies above 1000 Hz, the absorption efficiency increases due to changes in the porosity, pore size, and pore opening values rather than the thickness. However, for frequencies below 2000 Hz, increasing the absorption efficiency is strongly correlated with an increase in foam thickness. The PSO is successfully used to find optimum absorption conditions, the reference for absorbent fabrication, on a frequency band 250 to 8000 Hz. The outcomes will provide an efficient tool and guideline for optimum estimation of acoustic absorbents.

In this study, a flake-shaped metal powder was coated on a tube shaped pre-sintered 316L stainless steel support using a wet powder spraying process to fabricate a double pore structure, and the pore characteristics were analyzed according to coating time and tube rotation speed. The thickness of the coated layer was checked via optical microscopy, and porosity was measured using image analysis software. Air permeability was measured using a capillary flow porometer. As a result of the experiment, the optimal rotation speed of the support tube was established as 200 rpm. When the rotation speed was fixed, the coating thickness and the coating amount of the double pore structure increased as the coating time increased. The porosity of the double pore structure was increased due to the irregular arrangement of the flake-shaped powder. The air permeability of the double pore structure decreased with increasing fine pore layer thickness.

Fractal analysis is one of the rapidly evolving branches of mathematics and finds its application in different analyses such as pore space description. It constitutes a new approach to the issue of their natural irregularity and roughness. To be properly applied, it should be encompassed by an error estimation. The article presents and verifies uncertainties along with imperfections connected with image analysis and expands on the possible ways of their correction. One of key aspects of such research is finding both appropriate place and the number of photos to take. A coarse- grained sandstone thin section was photographed and then pictures were combined into one, bigger image. Fractal parameters distributions show their change and suggest that the accurately gathered group of photos include both highly and less porous regions. Their amount should be representative and adequate to the sample. The resolution influence on the fractal dimension and lacunarity values was examined. For SEM limestone images obtained using backscattered electrons, magnification in the range of 120x to 2000x was used. Additionally, a single pore was examined. The acquired results point to the fact that the values of fractal dimension are similar to a wide range of magnifications, while lacunarity changes each time. This is connected with changing homogeneity of the image. The article also undertakes a problem of determining fractal parameters spatial distribution based on binarization. The available methods assume that it is carried out after or before the image division into rectangles to create fractal dimension and lacunarity values for interpolation. An individual binarization, although time consuming, provides better results that resemble reality to a closer degree. It is not possible to define a single, correct methodology of error elimination. A set of hints has been presented that can improve results of further image analysis of pore space.

This paper presents the qualitative and quantitative characteristics of microstructures of Neogene clays from Warsaw, Poland. Scanning Electron Microscope (SEM) studies were used for the microstructural analysis of natural clays and clay pastes. Qualitative microstructural changes were observed: from a honeycomb microstructure for the initial clay paste to a turbulent microstructure for the dried paste. It was also noticed that water loss caused by the increase of the suction pressure had a significant impact on the microstructural transformations. Significant changes in the quantitative values of the pore space parameters were also observed. Increase of suction pressure and water loss caused a decrease in porosity and changes in the values of morphometric parameters, such as pore distribution; for example, a significant increase of the number of pores of 0−10 μm size and changes in the geometric parameters of the pore space were noticed with the increase of suction pressure. The pore space with larger isometric pores was modified into a pore space with the dominance of small anisometric and fissure-like pores. The increased degree of anisotropy from a poorly-oriented to a highly-oriented microstructure was also observed. After rapid shrinkage the reduction in the number of pores, maximum pore diameter, and total pore perimeter was recorded. The process of rapid water loss induced the closure of very small pores. A similar effect was observed during the increase of the suction pressure, where the closure of pore space of the clay pastes was observed very clearly.

Direct energy deposition (DED) is a three-dimensional (3D) deposition technique that uses metallic powder; it is a multi-bead, multi-layered deposition technique. This study investigates the dependence of the defects of the 3D deposition and the process parameters of the DED technique as well as deposition characteristics and the hardness properties of the deposited material. In this study, high-thermal-conductivity steel (HTCS-150) was deposited onto a JIS SKD61 substrate. In single bead deposition experiments, the height and width of the single bead became bigger with increasing the laser power. The powder feeding rate affected only the height, which increased as the powder feeding rate rose. The scanning speed inversely affected the height, unlike the powder feeding rate. The multi-layered deposition was characterized by pores, a lack of fusion, pores formed by evaporated gas, and pores formed by non-molten metal inside the deposited material. The porosity was quantitatively measured in cross-sections of the depositions, revealing that the lack of fusion tended to increase as the laser power decreased; however, the powder feeding rate and overlap width increased. The pores formed by evaporated gas and non-molten metal tended to increase with rising the laser power and powder feeding rate; however, the overlap width decreased. Finally, measurement of the hardness of the deposited material at 25℃, 300℃, and 600℃ revealed that it had a higher hardness than the conventional annealed SKD61.

The objective of this study is to analyze effect of ground granulated blast furnace slag (GGBFS) in concrete on the pore structure, this research will contribute to the knowledge regarding the use of GGBFS as a cementitious material in terms of the future reference and potential improvement to the properties of concrete. To this aim, on the one hand a control specimens (CS) and another samples with 40% and 60% of GGBFS as replacement cement with moist cured at 20oC, 27oC, and cured at site. The compressive strength and the Mercury intrusion porosimetry (MIP) test were done. The result indicates that the strength of concrete with GGBFS at early ages tend to be lower in comparison with the CS. However, the GGBFS reaction plays important roles at the later ages. The samples cured at higher temperature produce higher strength value. The total pore volume (TPV) of the concrete use GGBFS decreases with increasing age.

Cauchy paved the way for constructing models in concrete technology, and elsewhere. He determined the (nonflat) surface area in 3D by measuring random total projections. Analogously, he determined the length of a curved line in 2D by way of measuring the total projections. The paper will present the mathematical expressions, because in many branches of concrete technology, modelling is found based on such Cauchy concepts. These branches – fractography in compression, tension or shear, fibre reinforcement and permeability estimation – will briefly be mentioned to demonstrate this. It has been found that, for the discussed fields of engineering relevance, major model parameters for cementitious materials are similar to those developed by Cauchy in the 19th century. In the paper some previous investigations concerning fractography, fibre reinforcement and fracture roughness will be summarized but basically a new development on porosimetry will be presented. Particularly a new achievement of successful implementation of the methodology (also based on Cauchy) for optimizing permeability estimation will be discussed.

The pattern of pore water pressure dissipation from the one-dimensional consolidation test significantly affects the calculated value of the coefficient of consolidation. This paper discusses the interpretation methodology for laboratory dissipation data from the oedometer test with the pore water pressure measurements or Rowe cell test. In the analysis, the gradient-based algorithm for finding the optimal value of the coefficient of consolidation is used against experimental results, obtained for various fine-grained soils. The appropriate value of coefficient of consolidation is considered as one with the lowest associated error function, which evaluates fitness between the experimental and theoretical dissipation curves. Based on the experimental results, two different patterns of the pore water pressure dissipation are identified, and the saturation of the specimen was found to be the key factor in describing the change in the patterns. For the monotonically decreasing dissipation curve, an inflection point is identified. The values of degree of dissipation at the inflection point are close to the theoretical value of 53.4%.

The paper presents research on the influence of grain size of selected coals and their structural parameters on the diffusion coefficient and methane sorption isotherms. Two coals from Polish hard coal mines, differing in the coal rank, were tested. Sorption isotherms for methane were determined. An unconventional sequence of pressures 0→0.1→0→0.5→0→1.5 MPa was employed to assess the speed of achieving sorption equilibrium at different pressures. The studies of CH4 accumulation kinetics were performed on various grain classes of the tested coals. Both the sorption capacity of coal and the diffusion coefficient proved to be highly sensitive to the experimental methodology. Critical measurement parameters in terms of determining the diffusion coefficient concerning the assumptions of the Crank model were indicated. The influence of the equivalent radius of coal grain on the process kinetics was demonstrated. The stepwise pressure increase factor was examined in the context of minimising the impact of sorption isotherm non-linearity on the results. The importance of the width of the grain class of coals was determined to reduce their maceral inhomogeneities. These factors are the most common reason that makes it difficult to quantitatively compare diffusion coefficient values.

Microporous carbon molecular sieves of extremely narrow pore size distribution were obtained by carbonization of a novel raw material (Salix viminalis). The precursor is inexpensive and widely accessible. The pore capacity and specific surface area are upgradable by H3PO4 treatment without significant change of narrowed PSD. The dominating pore size indicates that these molecular sieves are a potential competitor to other nanoporous materials such as opened and purified carbon nanotubes.

Porous metals show not only extremely low density, but also excellent physical, mechanical and acoustic properties. In this study, Hastelloy powders prepared by gas atomization are used to manufacture 3D geometries of Hastelloy porous metal with above 90% porosity using electrostatic powder coating process. In order to control pore size and porosity, foam is sintered at 1200~1300°C and different powder coating amount. The pore properties are evaluated using SEM and Archimedes method. As powder coating amount and sintering temperature increased, porosity is decreased from 96.4 to 94.4%. And foam density is increased from 0.323 to 0.497 g/cm3 and pore size is decreased from 98 to 560 μm. When the sintering temperature is increased, foam thickness and strut thickness are decreased from 9.85 to 8.13mm and from 366 to 292 μm.

The objective of this investigation was comparing the penetration of chloride ions in ordinary and air-entrained concretes containing a waste material Fluidized Bed Combustion Fly Ash (FBCFA). All concretes were tested with 15% and 30% cement replacement by FBCFA, with the same water-binder ratio of 0.45. Two kinds of fly ash coming from fluid bed combustion in two power plants in Poland have been used.

In this study the rapid chloride permeability test – Nordtest Method BUILD 492 method – was used. The microstructure of the concrete was analyzed on thin polished sections and the measurement of air voids sizes and their distribution, using digital image analysis, was carried on according to PN-EN 480-11:2008.

Obtained results have shown a significant influence of partial cement replacement by FBCFA on the chloride ions movements in concrete. It has been found that this kind of addition reduced considerably the chloride ion penetration. The influence of air entrainment on the chloride diffusion coefficients was also measured and it was shown that application of air-entraining admixture for concretes with FBCFA reduce the chloride diffusion coefficient but it should be used with caution.

In this study, a SUS316L membrane having double layered pore structures was fabricated, and the pore characteristics were analyzed after coating with a spherical powder and a flake-shaped powder on a disk-shaped SUS316L support using a wet powder spraying process. The thickness of the coated layer was checked using an optical microscope, and air permeability was measured using a capillary flow porometer. When the coating amount was similar, the fine porous layer prepared using flake powder was thicker and showed higher porosity. In the case of a similar thickness, the case of using flake powder was half of the amount of spherical powder used. Therefore, it was confirmed that it is possible to manufacture a metal membrane having a high filter efficiency even with a small coating amount when using the flake powder.

Several field and model tests have been conducted to investigate the impact of pile installation on bearing capacity. However, little is known about how piles behave during installation, how they interact with the surrounding soil, and how this affects sandy soil properties. This review paper investigates the effect of pile driving on surrounding sandy soil as it compacts sandy soil near to the pile. For this purpose, various related literature was studied based on the observation of the pile installation effect on earth pressure or lateral stress, relative density, and pore water pressure in the sandy soil. A change in the deformation and stress state of surrounding sandy soil due to pile driving was presented. The installation of fully displacement piles can lead to significant stresses and deformations in the surrounding sandy soil. This is one of the main causes of uncertainty in the design and analysis of pile foundations. According to this study, the sandy soil around the pile is compacted during pile driving, resulting in lateral and upward displacement. This leads to the densification effect of pile driving on loose sandy soil. Sandy soil improvement with driven piles depends on pile shape, installation method, and pile driving sequences. This study concludes that in addition to its advantages of transferring superstructure load to deep strata, the increased relative density of loose sand, the change in the horizontal stress, and the influence of compaction on the sandy soil parameters during pile driving should be considered during pile design and analysis.

A fast reduction of a reservoir level may result in instability of an earth dam caused by the high pore water pressures that remain relatively high in the embankment. Moreover, the dissipation of the accumulated pore water pressures is highly dependent on the permeability of the materials used for the embankment and the storage characteristics of the reservoir. Therefore, in the design of embankment dams, the stability analysis under rapid drawdown loading conditions is an important design case. In this study, the influence of different permeability rates on dam stability under different cases of rapid drawdownwas investigated using the finite element method in SEEP/W and SLOPE/W of the GeoStudio with a case of the Lugoda dam in Ndembera catchment, Tanzania. The modeling process considers the time-dependent hydraulic conditions and the transient flow conditions using different water levels during rapid drawdown for evaluation of the factor of safety. From the 1m per day drawdown rate; the lowest minimum factor of safety value (0.90) was obtained from the 10 ^-7 m/s material permeability of the upstream zone of the dam. It means that, at a drawdown rate of 1m per day, there is a potential for failure of the embankment if the hydraulic conductivity value will be somewhere below 10 ^-6 m/s.

Slope Stability Analysis is one of the main aspects of Open-pit mine planning because the calculations regarding the stability of slopes are necessary to assess the stability of the open pit slopes together with the financial feasibility of the mining operations. This study was conducted to analyse the effect of groundwater on the shear strength properties of soft rock formations and determine the optimum overall slope angle for an open pit coal mine at Thar Coalfield, Pakistan. Computer modelling and analysis of the slope models were performed using Slide (v. 5.0) and Phase2 (v. 6.0) software. Integrated use of Limit Equilibrium based Probabilistic (LE-P) analysis and Finite Element Method (FEM) based shear strength reduction analysis was performed to determine the safe overall slope angle against circular failure. Several pit slope models were developed at different overall slope angles and pore-water pressure ratio (Ru) coefficients. Each model was initially analysed under dry conditions and then by incorporating the effect of pore-water pressure coefficients of Ru = 0.1, 0.2, and 0.3 (partially saturated); finally, the strata were considered to be fully saturated. It was concluded that at an overall slope angle of 29 degrees, the overall slope will remain stable under dry and saturated conditions for a critical safety factor of 1.3.

The roof-caving step scale goaf behind the working face is sensitive to the region’s spontaneous combustion and gas concentration distribution, including many rock block cracks and holes. A severe deviation from the dynamics of fluids in porous media by representative element volume (REV), leading to the results of Computational Fluid Dynamics (CFD) simulation, has a significant error. A heterogeneous two-dimensional pore network model was established to simulate the goaf flow accurately. The network was first created using the simple cubic lattice in the OpenPNM package, and the spatial distribution of the “O-ring” bulking factor was mapped to the network. The bulking factor and Weibull distribution were combined to produce the size distribution of the pore and throat in the network. The constructed pore network model was performed with single-phase flow simulations. The study determined the pore structure parameters of the pore network through the goaf’s risked falling characteristics and described the flow field’s distribution characteristics in the goaf. The permeability coefficient increases as pore diameter, throat diameter, pore volume and throat volume increase and increases as throat length decreases. The correlation between throat volume and permeability coefficient is the highest, which indicates that the whole throat is the main control factor governing the air transport capacity in the goaf. These results may provide some guidelines for controlling thermodynamic disasters in the goaf.