This study discusses results of experiments on hydrodynamic assessment of gas flow through backbone (skeletal) porous materials with an anisotropic structure. The research was conducted upon materials of diversified petrographic characteristics – cokes. The study was conducted for a variety of hydrodynamic conditions, using air. The basis for assessing hydrodynamics of gas flow through porous material was a gas stream that results from the pressure forcing such flow. The results of measurements indicate a clear impact of the type of material on the gas permeability, and additionally – as a result of their anisotropic internal structure – to a significant effect of the flow direction on the value of gas stream. In aspect of scale transfer problem, a method of mapping the flow geometry of skeletal materials has been developed and usefulness of numerical methods has been evaluated to determine pressure drop and velocity distribution of gas flow. The results indicate the compliance of the used calculation method with the result of experiments.
Moulding properties of Isasa River Sand bonded with Ipetumodu clay (Ife-North Local Government Area, Osun State, Nigeria) were
investigated. American Foundry men Society (AFS) standard cylindrical specimens 50mm diameter and 50mm in height were prepared
from various sand and clay ratios (between 18% and 32%) with 15% water content. The stress-strain curves were generated from a
universal strength testing machine. A flow factor was calculated from the inclination of the falling slope beyond the maximum
compressive strength. The result shows that the flowability of the samples increases from 18% to 26% clay content, its maximum value
was attained at 26% and then it decreases from 30% to 32% clay content. The green compressive strength, dry compressive strength and
air permeability values obtained from the mould samples were in accordance with standard values used in foundry practice. The x-ray
diffraction test shows that the sand contains silicon oxide (SiO2), Aluminium oxide (Al2O3), and Aluminium silicate (Al6Si2O13). The
mould samples were heated to a temperature of 1200 o
C to determine the sintering temperature; fussion did not take place at this
temperature. The results showed that the sand and clay mixture can be used to cast ferrous and non-ferrous alloys.
The study was aimed to determine the hydrodynamic of water seepage through a porous bed saturated with different amounts of high viscosity liquids. An attempt was made to describe the process of seepage through beds saturated with oils using the theory of outflow of a liquid from the tank. It was assumed that the discharge coefficient will represent changes of flow resistance during the process. It was found that the dependence of this factor on time is linear. In the second part of this work kinetics of the seepage process was investigated. Dependence of oil concentrations, eluted from the deposit with the flowing water, on time has been evaluated. Thanks to these studies it was possible to determine the effectiveness of an elution of high viscosity liquids from porous beds using water as the washing out liquid.
The drainage consolidation method has been efficiently used to deal with soft ground improvement. Nowadays, it has been suggested to use a new sand soil which is a composite of sand and recycled glass waste. The permeability performance of glass-sand soil was explored to judge the feasibility of glass-sand soil backfilled in the drainage consolidation of sand-drained ground. For comparison purposes, different mix proportions of recycled glass waste, fineness modulus, and glass particle size were analyzed to certify the impact on the permeability coefficient and the degree of consolidation. The numerical results show that adding a proper amount of recycled glass waste could promote the permeability performance of glass-sand soil, and the glasssand soil drain could be consolidated more quickly than a sand drain. Experiments showed that glass-sand soil with the a 20% mix of recycled glass waste reveals the optimum performance of permeability.
The objective of the presented paper is to investigate the performance of concrete containing volcanic scoria as cement replacement after 7, 28, 90, and 180 days curing. Five performance indicators have been studied. Compressive strength, water permeability, porosity, chloride penetrability, and reinforcement corrosion resistance have all been evaluated. Concrete specimens were produced with replacement levels ranging from 10 to 35%. Test results revealed that curing time had a large influence on all the examined performance indicators of scoria-based concrete. Water permeability, porosity, and chloride penetrability of scoria-based concrete mixes were much lower than that of plain concrete. Concretes produced with scoria-based binders also decelerated rebar corrosion, particularly after longer curing times. Furthermore, an estimation equation has been developed by the authors to predict the studied performance indicators, focusing on the curing time and the replacement level of volcanic scoria. SEM/EDX analysis has been reported as well.
The correct management of underground works, petroleum and gas reservoirs and geothermal applications relies on the hydromechanical behaviour of rock masses. We describe a laboratory approach to measuring permeability for different types of rock specimens. A laboratory system was designed and set up using rock mechanics equipment (a servo-controlled hydraulic press, a Hoek cell, a pump for injecting water and a scale for measuring the volume of water flow). To verify the validity of the permeability measurements, tests were carried out on a reference porous rock (Corvio sandstone), with results showing good agreement with those published in the literature. Tests were subsequently carried out on artificially fissured granite specimens with different joint patterns, submitted to various confinement stresses up to 20 MPa. Results showed good agreement with traditional Klinkenberg test results. Other tests done with artificially fissured specimens are described for demonstrative purposes.
The article presents the results of permeability measurements of a zirconium alcohol coating applied on moulds and cores. The introduction extensively discusses the reasons for the application of protective coatings, as well as their advantages and disadvantages. Also, the problems related to the application of protective coatings are presented i.e. limited permeability and thus the possibility of the presence of gas-originated defects in the casts. Next, the paper discusses the methods of measuring the permeability of protective coating proposed by Falęcki and Pacyniak. The study also presents an indirect permeability measurement method. For the investigations, zirconium alcohol coatings with the three conventional viscosities 10, 20 and 30s were used. The viscosity was determined by means of the Ford cup with the clearance of 4mm. The coatings were applied onto profiles of Φ 50 x 50 mm, made of moulding sand consisting of a sand matrix with the mean grain size of dL = 0,11, 17, 24, 31 and 34 mm and phenol-formaldehyde resin. The effect of the matrix grain size on the permeability of the sand with and without a coating was determined.
Pervious concrete is a unique and effective material used to tackle important environmental problems, to maintain green, sustainable growth, and to reduce storm water runoff and pollutants. Clogging of pervious concrete is an important potential issue in serviceability, considered one of the primary limitations of pervious concrete systems. The sediment deposition pattern of pervious concrete was determined using three clogging materials: clay, sand, and clayey silty sand. The clogged specimens were cleaned by pressure washing, vacuuming, and a combined method. In total, ten clogging and cleaning cycles were carried out on each sample to evaluate the draining capacity of the pervious concrete. The clogging test was assessed by measuring the infiltration rate during clogging and after cleaning, for each cycle. The experiment results showed that a reduction in permeability due to different types of sedimentation material as well as recovery in permeability was achieved after applying various cleaning methods.
The fungi that cause sooty blotch grow only on the apple skin, so they use appropriate nutrients which are present on the fruit surface. It has been shown that when the first symptoms of sooty blotch occur a noticeable increase of glucose and fructose content both on the apple skin and in juice is observed. Such increase occurs at pH 4.4. An effect of surface glucose and fructose on the growth of patho- gens responsible for the disease was also confirmed by evaluating the germination of conidia of Phialophora sessilis de Hoog and Peltaster fructicola Jonhson in solution of above mentioned sugars, distilled water and standard d-glucose solutions.
In this paper the application of so called wedge functions is presented to solve two-dimensional simple geometries of magnetostatic and electrostatic problems, e.g. rectangles of varying aspect ratio and with different values of the magnetic permeability μ. Such problems require the use of surface charge density, or segment source, functions of the form ρs = σa-1, where the power parameters, a, have special fractional values. A methodology is presented to determine these special values of a and use them in segment sources on simple geometries, i.e. rectangles of varying aspect ratio, and with different values of the magnetic permeability μ. Wedge solutions are obtained by coupling the strength coefficients of source segments of the same power around an edge. These surface source functions have been used in the analysis of conducting and infinite permeability structures. Here we apply such functions in a boundary integral analysis method to problems having regions of finite permeability.
We fabricated two different kinds of composite materials for absorbing microwave in a frequency range of 2 to 18 GHz using coaxial airline and thru-reflect-line (TRL) method. The composite materials having carbon nanotube (CNT) with carbonyl iron (CI) or iron oxide (Fe3O4) were fabricated by mixing each components. Magnetic properties were measured by SQUID equipment. Complex permittivity and complex permeability were also obtained by measuring S-parameters of the toroidal specimen dispersing CI/CNT and Fe3O4/CNT into the 50 weight percent (wt%) epoxy resin. The real permittivity was improved by mixing the CNT however, the real permeability was same as pure magnetic powders. The CI/CNT had a maximum value of real permittivity and real permeability, 11 and 1.4 at 10 GHz, respectively. The CNT composites can be adapted to the radar absorbing materials, band width 8-12 GHz.
This paper presents the results of research on high performance
concretes (HPC) modified by theaddition of polypropylene fibres
(PP
fibres). The scope of the research was the measurement of theresidual
transport properties of heated and recooled concretes: gas permeability
and surface waterabsorption. Seven types of concrete modified with
fibrillated PP fibres were tested. Three lengths: 6,12 and 19 mm and
three amounts of fibres: 0, 0.9 and 1.8 kg/m3 were used. The research
programmewas designed to determine which length of fibres, used in which
minimum amount, will, after thefibres melt, permit the development of a
connected network and pathway for gases and liquids.
In this work, the influence of microwave drying parameters such as irradiation time and microwave power level on the properties of synthetic moulding sands is presented. Determination of compressive strength Rc s, shear strength Rt s and permeability Ps of synthetic moulding sands with the addition of two different bentonites, after drying process with variable microwave parameters were made. The research works were carried out using the microwave oven with regulated power range of the electromagnetic field. From the results obtained, the significant influence of both drying time and microwave power level on the selected properties of moulding sands was observed. In comparison to the conventional drying method, microwave drying allows to obtain higher compressive strength of the synthetic moulding sand. The influence of application microwave irradiation on permeability was not observed. Higher strength characteristics and shorter drying time are major advantages of application of the electromagnetic irradiation for drying of the synthetic moulding sand with regard to conventional drying method.
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.
en
pl
