Apparent Specific Gravity Research Articles

Preparation and characteristics of moulded biodegradable cellulose fibers/MPU-20 composites (CFMCs) by steam injection technology

In this work, the moulded cellulose fibers/MPU-20 composites (CFMCs) with apparent specific gravity lower than 100 kg/m 3 and thickness of 20–200 mm have been successfully manufactured using a new design of steam injection technology and equipment. It was found that the CFMCs have good cushioning properties, with a cushion factor lower than 4. Two yield deformation stages were observed in the compressive process. Compressive stress–strain and cushion factor-stain curves were measured as a function of steam injection pressure, transmission time, holding time, MPU-20 resin dosage and apparent specific gravity. Chemical groups, crystallinity, and thermal properties of samples were studied through the use of FTIR spectroscopy, X-ray diffraction (XRD), and DTA–TGA. In addition, the microstructure and morphology were investigated by scanning electron microscope (SEM) and atomic force microscope (AFM).

Planejamento experimental aplicado à otimização de massas cerâmicas contendo matérias-primas naturais

A otimização da composição é uma etapa de fundamental importância no processamento cerâmico. Neste trabalho, planejamento experimental foi aplicado a fim de se avaliar a relação entre propriedade e a composição de um sistema obtido a partir de matérias-primas naturais extraídas no Pegmatito do Seridó, na região fronteiriça RN-PB. Para o estudo do sistema ternário foram combinadas variáveis de processo (temperatura: 1100 e 1200 ºC; patamar de calcinação: 0 e 2 h), com a utilização de planejamento de misturas, de acordo com o planejamento simplex centróide. Os percentuais mínimos de cada componente na mistura foram de 10% v/v. Foram avaliadas as propriedades reológicas de suspensões aquosas das misturas com 50% v/v, otimizadas com PAA-Na. Determinou-se a porosidade aparente e massa específica aparente, além da retração de queima. A composição mineralógica das peças cerâmicas obtidas a 1200 ºC foi basicamente mulita e quartzo. O estudo permitiu especificar a região de composição que leva à maior densidade após sinterização, com um número relativamente pequeno de amostras.

Influence of Water Content on Ultrasonic Pulse–Echo Measurements Through High Volume Fly Ash Cement Paste—Physicomechanical Characterization

In this study, physicomechanical characterization is evaluated using ultrasonic pulse–echo measurements through high-volume fly ash (HVFA) cement paste. The composites were tested at different water-content levels to infer their influence on the pulse–echo measurements. To achieve different water content levels, samples were dried in an oven between 60 and 105°C at 6-, 12-, and 24-h intervals. Physical (dry unit weight, apparent specific gravity, porosity at 7 and 28 days) and mechanical (unconfined compression test at 7 and 28 days) measures were performed. The research indicates that the degree of saturation significantly affects the ultrasonic pulse–echo of HVFA cement paste. The empirical relations of the physical and mechanical properties with ultrasonic pulse velocity are highly correlated.

Efficiency of densification process in preparation of carbon-carbon composites

Material balance of densification process was made to assess its efficiency in dependence on impregnation conditions. Theoretical values of apparent porosity, bulk density and apparent specific gravity were computed and compared with experimental ones. Densification efficiency was determined as the ratio of volume of added matrix to volume of pores. Key Words: Composites, Polymers, Structural behaviour, Porosity

ESTUDIO DE LAS PROPIEDADES FISICO-MECÁNICAS Y COMPORTAMIENTO EN PROCESOS INDUSTRIALES DE LA MADERA DE KIRI, GREVILLEA, PARAÍSO Y TOONA

Este trabajo tuvo por objetivo determinar las propiedades físicas y mecánicas, así como el comportamiento en distintos procesos industriales, de maderas de las especies: paraíso (Melia azederach), kiri (Paulonia tomentosa), toona (Toona ciliata) y grevillea (Grevillea robusta), cultivadas en la Provincia de Misiones, Argentina. Las propiedades estudiadas fueron peso específico, contracción total, coeficiente de retractabilidad, anisotropía de contracción y flexión estática, bajo las Normas IRAM N° 9544, 9543 y DIN N° 52186. Grevillea, paraíso, toona y kiri presentaron valores medios de pesos específicos aparente de 0,530 g/cm³; 0,600 g/cm³; 0,422 g/cm³ y 0,270 g/cm³ respectivamente. La contracción total en la dirección tangencial de las maderas de paraíso, toona, grevillea y kiri presentaron los valores de 6,82 %; 7,85 %; 5,69 % y 4,51 % respectivamente; en la dirección radial de las mismas maderas presentaron los valores de 5,44 %; 4,11 %; 3,5 % y 1,57 % respectivamente. La madera de paraíso fue la que presentó valores superiores de módulos de rotura y elasticidad 852,89 kg/cm² y 72505 kg/cm², respectivamente. La grevillea presentó valores menores con respecto al paraíso tanto en el módulo de rotura como en el módulo de elasticidad, 521,55 kg/cm² y 45693 kg/cm² respectivamente. La madera de toona presentó un valor medio del módulo de rotura y elasticidad de 468 kg/cm² y 65118 kg/cm², respectivamente. La madera de kiri, como es de esperar, arrojó valores de los módulos de rotura de 256,85 kg/cm² y elasticidad a la flexión estática 25261,52 kg/cm², menores que las especies ya citadas. El rendimiento en el proceso de aserrado de las maderas fue: kiri, 50%; grevillea, 48%; toona, 50% y paraíso, 55%.

Formcoke production from char fines of hard brown coals by air curing

The purpose of the present study was to explore the technical feasibility of formcoke production from non-coking bright hard brown coals and pitch as a binder by air curing. The briquettes obtained from the chars of Soma coals carbonised at 500, 600, 700, 800 and 900°C with 12% pitch were air cured in a streaming gas containing 16%O2(air + N2) for 120 min at 270°C and the formcoke strength was found to be 10–40% higher than that of raw briquettes. Under the prevailing conditions, the formcoke strength and the apparent specific gravity of the green and formcoke briquettes increased as the carbonisation temperature increased, reaching a maximum at the optimum carbonisation temperature of 800°C. M40 and M10 values and the compressive strength of SK800 formcokes were determined to be 92·3, 7·7% and 23·5 MPa respectively being similar to those of conventional cokes produced at coke ovens. The optimum curing conditions (pitch content, curing time and temperature) were determined using TK800 char. The optimum curing time for TK800 briquettes at 220°C was determined to be 90 min. The formcoke strength of TK800 briquettes subjected to a thermal treatment at 220°C was lower than that of the briquettes air cured at the same temperature. The optimum curing temperature for TK800 briquettes with 10% pitch and cured in a gas stream containing 16%O2 in terms of formcoke strength was determined to be 285°C. M40 and M10 values and the compressive strength of TK800 formcokes were determined to be 91, 8·1% and 19·6 MPa respectively. The experimental results reveal the advantages of the method because the formcokes produced possess suitable properties for various metallurgical processes and smokeless fuel consumption. The gas and tar obtained during the carbonisation of raw coal are the added benefits.

High Strength, Ultralightweight Proppant Lends New Dimensions to Hydraulic Fracturing Applications

Summary Since the earliest fracturing treatments more than 50 years ago, many different materials have been used including sand, glass beads, walnut hulls, and metal shot. Today's commonly used proppants include various sands, resin-coated sands, intermediate-strength ceramics, and sintered bauxite—each employed for its ability to cost-effectively withstand the respective reservoir closure stress environment. As the relative strength of the various materials increases, so too have the respective particle densities, ranging from 2.65 g/cm3 for sands to 3.4 g/cm3 for the sintered bauxite. Unfortunately, increasing particle density leads directly to an increasing degree of difficulty with proppant transport and a reduced propped-fracture volume for equal amounts of the respective proppant, thereby reducing fracture conductivity. Intuitively, one expects that a lesser-density proppant would be easier to transport, allowing for reduced demands on the fracturing fluids, and if it had sufficient strength, would provide increased width, and hence, enhanced fracture conductivity. Previous efforts undertaken to employ lower-density materials as proppant have generally resulted in failure because of insufficient strength to maintain fracture conductivity at even the lowest of closure stresses (1,000 psi). Recent research on material properties has at last led to the development of an ultralightweight (ULW) material with particle strength more than sufficient for most hydraulic fracturing applications. The current ULW proppants have apparent specific gravities of 1.25 and 1.75 g/cm3. Laboratory tests will demonstrate exceptional fracture conductivity at stresses to 8,000 psi. This paper presents data illustrating the performance of the new ULW proppant over a broad range of conditions and a discussion of relative performance in field applications.

コンクリート廃材リサイクルのためのモルタルと砂利の乾式比重分離

Fluidized bed medium separation (FBMS) was applied to the gravity separation of mortar and gravel for the recycle of waste concrete. Zircon sand (Z. S.)/glass beads (G. B.) and zircon sand/steel shots (S. S.) mixtures with various volume mixing ratios were employed as fluidized particles. Apparent specific gravity and the dispersion of a cylindrical fluidized bed were adjusted to 2.1-2.7 and less than 0.1 respectively by changing the volume mixing ratio of fluidized particles and the superficial velocity and then the mortar and gravel were loaded into the bed. As a result, the mortar and gravel were completely separated at the conditions that the volume mixing ratio was G. B.:Z. S.:S. S.=0:100:0 at the ratio of superficial velocity to the minimum fluidization velocity, u0/umf=2.0, for the fluidized time of 10min. Furthermore, half batch type pilot-scale FBMS device (Gravity separation system with a new device that can discharge floating and sinking objects) was developed. Recoveries of mortar and gravel were investigated by floating-sinking experiments with the device. The recoveries of mortar and gravel were nearly 100% and 95%, respectively. High rate of recoveries was attained in with the FBMS using the new device.

２成分粒子系固気流動層における見掛け比重の制御

２成分粒子系固気流動層における見掛け比重の制御

Evaluation of Test Equipment for Determination of Fine Aggregate Specific Gravity and Absorption

Concern has been expressed about the repeatability of the current AASHTO T 84 method for determination of fine aggregate specific gravity. Two new methods are available for determining bulk specific gravity and absorption of fine aggregates: the AggPlus system using the CoreLok device and the SSDetect system. In addition, a new automated Langley de-airing device is available for AASHTO T 84. The objectives of this study were (a) to evaluate the reproducibility of SSDetect, CoreLok, AASHTO T 84, and AASHTO T 84 with the Langley de-airing device and (b) to determine if either of the new systems would produce results statistically similar to those produced by the current AASHTO T 84 procedure. The AASHTO procedure, when used with the Langley de-airing device, gave similar results to AASHTO T 84 but with reduced variability. The SSDetect procedure produced the highest bulk specific gravity and lowest percent absorption followed by the CoreLok and AASHTO T 84 procedures. There was no significant difference in apparent specific gravity values. Increasing the cure time for the SSDetect procedure resulted in increased saturated surface dry mass.

Material Properties of High Volume Fly Ash Cement Paste Structural Fill

Fly ash can be effectively used as compacted or flowable fill material in the construction of structural fills for building foundations, embankments, base and subbase courses for highways and railroads, dikes, levees, bridge abutments, and landfill cover in lieu of conventional earth materials. In this study, high volume fly ash cement paste composite formed of various combinations of fly ash, cement, lime, silica fume, and chemical admixtures has been examined in terms of its physical (dry unit weight, void ratio, apparent specific gravity, linear shrinkage), mechanical (unconfined compressive strength, flexural strength), and durability properties (hydraulic conductivity, soundness by use of sodium sulphate) at 0, 100, and 200mm slump values. The results indicate that the cement paste, providing certain advantages over conventional fill materials with its lower unit weight, higher strength, and higher volume stability can be designed for any required engineering performance for use in the construction of compacted to self-compacting structural fills and promises high volume fly ash utilization with low technology requirements avoiding scarce use of raw resources.

Properties and microstructure of lightweight aggregate produced from sintered sewage sludge ash

The properties of lightweight aggregate (LWA) manufactured from the ash produced by fluidised bed incineration of sewage sludge have been investigated. The ash was mixed with a clay binder, formed into approximately spherical pellets and rapidly sintered in a rotary tube furnace at temperatures between 1020 and 1080 °C. Selected physical properties of sintered ash pellets relevant to use as lightweight aggregate have been determined, including density (apparent specific gravity), water absorption and compressive (crushing) strength. These have been compared to the properties of a commercially available lightweight aggregate (Lytag). Sewage sludge ash (SSA) pellets sintered over a range of temperatures were found to have lower densities than Lytag and low water absorption when fired between approximately 1050 and 1080 °C. Individual pellet strengths were comparable to Lytag. Major crystalline phases present in both as-received and sintered sewage sludge ash were quartz (SiO 2), the calcium magnesium phosphate mineral whitlockite (Ca 7Mg 2P 6O 24) and hematite (Fe 2O 3). Manufacturing lightweight aggregate from sewage sludge ash may become increasingly viable as landfill disposal costs continue to increase and the costs of alternative natural aggregates obtained from increasingly distant locations also increase. Sewage sludge incinerators tend to be situated in urban areas, close to where construction activity is occurring. The results indicate the potential for manufacturing high quality lightweight aggregate from the sterile, inert ash produced by sewage sludge incineration, using relatively simple processing and low temperature sintering.

An Alternate Method to Determine Asphalt Content of Hot Mix Asphalt Using Volumetric Properties

Abstract Accurate determination of asphalt content (AC) in hot mix asphalt (HMA) is essential to evaluate the performance characteristics of HMA pavements. The standard test methods for determining the AC, currently used by the Oklahoma Department of Transportation (ODOT) and other DOTs and asphalt industries, are time-consuming, environmentally unsuitable, and not applicable to several absorptive and dolomitic aggregates. This study has developed a systematic method for the determination of AC using volumetric properties of aggregate, asphalt, and HMA mix. The developed method employed the theoretical maximum specific gravity (Gmm) of an HMA mix, the bulk and apparent specific gravity of the aggregate (Gsb and Gsa), and the specific gravity of the asphalt binder (Gb). The CoreLok™ device is used to determine the volumetric properties of the aggregate and HMA mix. This developed method is easy to use, environmentally safe, time efficient, and accurate. Three different aggregates were selected for the study based on varying gradation, absorption, and ignition oven correction (IOC) factor. HMA mixes were prepared with each of these aggregates using 5.0 %, 5.5 %, and 6.0 % AC. For each of the mixes, AC was calculated using the proposed method and compared with the actual AC value. The predicted AC values were compared with AC values from the ignition oven method (AASHTO T 308) and the solvent extraction method (AASHTO T 164). Results showed that the proposed method predicted the AC of HMA mix accurately. The method introduces a correction factor (Cv), which needs to be determined during the design stage and specified on the mix design information. The Cv value is used to calculate AC by the proposed method during quality assurance and quality control at the production and service life of HMA.

Evaluation of New Test Procedures for Determining Bulk Specific Gravity of Fine Aggregate by Automated Methods

Two automated methods were evaluated for determining the dry bulk specific gravity ( Gsb) of fine aggregates: Thermolyne SSDetect and InstroTek CoreLok. Each proposed method was evaluated against the standard method described in AASHTO T-84. The evaluation was based on a round-robin study with 12 laboratories and six materials, four crushed fine and two uncrushed (natural) fine aggregate sources. The CoreLok and SSDetect methods of determining fine aggregate specific gravity offer significant timesavings over AASHTO T-84. Both the CoreLok and SSDetect methods generally produce Gsb results similar to AASHTO T-84. It is believed that AASHTO T-84 may not produce accurate results for angular materials with high dust contents. More frequent statistical differences exist between the CoreLok and SSDetect apparent specific gravity (Gsa) and water absorption results than those produced by AASHTO T-84. However, Gsa and water absorption are not used in volumetric calculations for hot-mix asphalt. SSDetect offers improved precision over AASHTO T-84. The precision of the CoreLok method is slightly worse than that of AASHTO T-84, but it is expected to improve as technicians become more familiar with the procedure.

폐스티로폼의 가공 형태에 따른 기포콘크리트의 물리적 특성 변화

본 연구는 기존 경량기포콘크리트의 문제점 및 역학적 성질의 개선을 위하여 산업폐기물인 폐스티로폼의 가공형태를 달리하여 기포콘크리트를 제조하고 그 역학적 특성의 변화를 구명해 봄으로써 현장타설 기포콘크리트의 효과적인 품질관리를 위한 자료를 제공하고, 현장 작업자에게 필요한 실험값을 제공하는 것을 목적으로 한다. 폐스티로폼은 지름이 3~5mm의 둥근형태를 유지한 것(Type A)과 1~2mm의 작게 파쇄한 것(Type B)을 사용하여 그 역학적 특성 변화를 고찰하였으며, 연구결과 Type A의 경우 흡수율의 개선과 경량성 및 단열성 향상에 유리한 것으로 나타났으며, Type B의 경우는 높은 압축강도를 나타내나 겉보기 비중이 증가하고 Type A에 비하여 플로우, 흡수율, 단열성에서 Type A보다 낮은 성능을 나타냈다. 그러나 이러한 결과로부터 폐스티로폼의 가공형태에 따른 것으로 폐스티로폼을 사용하지 않은 것보다는 적당량을 혼입하여 사용하는 것이 현장타설 기포콘크리트의 물리적 성능을 향상시키는데 효과적임을 알 수 있었다. 결과적으로 폐스티로폼을 사용하여 현장타설 기포콘크리트를 제조할 경우 산업폐기물의 재활용이라는 측면과 함께 보다 우수한 성능의 기포콘크리트 생산이 가능함을 확인하였다. This study is focusing on mixing the foamed concrete incorporated by waste expanded polystyrene(W-EPS), investigating the physical properties and offering a proper quality control method to the field engineers. Two types of W-EPS (type A and type B) were studied. Type A (B) had globular (crushed) shape and diameter of 3-5 (1-2) mm. The results show that the flow was suddenly reduced with increasing mixing quantity of two types, but it satisfies KS F 4039 until 60 ％ of mixing rate. In general, the absorption rate was suddenly reduced with increased mixing quantity of two types especially, in type A. Apparent specific gravity was 0.36∼0.53 and reduced with increasing mixing quantify of type A. But it increased in case of type B. Compressive strength and heat conduction rate increased with mixing with W-EPS than non-mixing W-EPS but reduced with mixing too much W-EPS. Based ong the results, it is believed that mixing with W-EPS can improve the recycle of industrial wastes and produce the high quality foamed concrete.

Panel for constituting sound insulating wall

A panel for constituting sound insulating wall is provided with a front plate, a rear plate, and a sound absorbing material put between the plates. The sound absorbing material contains reduced plastic products coated with magnetic material such as magnetic tape and magnetic sheet. The front plate is provided on the sound source side and constituted of a plate having numerous holes. The sound absorbing material is composed of a permeable bag and the reduced plastic products in the bag so that the apparent specific gravity and permeation resistance can be 0.05-0.4 and 3-90 dyn.S/cm4, respectively. The reduced plastic products may be reduced plastic products alone not subjected to other processings, or may be a mixture of reduced plastic products and molded bodies of reduced plastic products. Alternatively, only molded bodies of reduced plastic products can be put in the permeable bag. Therefore, an inexpensive panel for constituting sound isolating wall which has an excellent sound absorbing characteristic, a moisture resistance, a water resistance, and a light weight can be fabricated by utilizing plastic products coated with magnetic material such as magnetic tape and magnetic sheet, and particularly scrap of plastic products.

EFFECT OF MUSHROOM SPENT RICE STRAW COMPOST ON SOIL PHYSICAL AND PHYSICO-CHEMICAL PROPERTIES OF ALLUVIAL AND LATERITE SOILS

The absolute and apparent specific gravity values were appreciably influenced by the incorporation of mushroom spent rice straw compost whereas the water holding capacity, porosity and volume expansion on wetting were markedly improved by farmyard manure closely followed by composted coirpith and mushroom spent compost in an alluvial soil. However, in laterite soil, all the physical properties investigated were found to be influenced by the application of manures in the order of farmyard manure > mushroom spent compost > composted coir pith > NPK whereas the soil reaction and the total soluable salts of post harvest soil samples of both the soils were not influenced due to the application of organic manures in combination with NPK fertilizers.

Crushed Tile Coarse Aggregate Concrete

Abstract This paper investigates the potential of crushed tiles as coarse aggregate in concrete. Test results of bulk, saturated surface dry (SSD) and apparent specific gravities, bulk unit weight, water absorption, resistance to abrasion, percent of voids and grading (performed as per ASTM standards) on two types of crushed tiles were compared with the results of conventional crushed stone aggregate. Also included are results from tests on concrete cylinders under uniaxial compression, split tension, and beams under flexure to determine the influence of variables of test age on concrete strength, type of tiles, and ratio of volume of crushed tile to the total volume of coarse aggregate in concrete. Recommendations for use of crushed tile as coarse aggregates in concrete are given.

The influence of condensation method on porosity and shade of body porcelain

Condensation of porcelain is an important laboratory variable that can affect a variety of physical properties in metal ceramic restorations. This study examined four methods of condensation (brush with vibration, ultrasonic vibration, spatulation, and noncondensation) to evaluate their effects on porosity and color. Standardized 12 × 12 mm acetate plastic squares were invested and cast with Olympia alloy. After oxidation, the metal substructures received one of the following opaque and body porcelains: Ceramco II G Series, Will-Ceram V-Series, Vita VMK-68, or Jelenko. The examination of each sample consisted of three parts: (1) apparent specific gravity analysis (porosity); (2) tristimulus colorimeter analysis; and (3) subjective observer color analysis. No statistical differences ( p ≤ 0.05) in apparent specific gravity were found between methods of condensation within any of the four porcelains. Statistical differences ( p ≤ 0.05) in color were noted between methods of condensation within several of the porcelains by both the tristimulus colorimeter and the subjective observers.

アルミニウム合金ダイカスト実用鋳物の欠陥と強度

Causes for scattering of the tensile strength values were investigated on specimens which were cut from various parts of aluminum castings (ADC10, 12) made by die casting machines (5-20MN). The strengths of non-defect specimens are 200-350MPa. In the case where the distance along the flow of molten metal from the gate is less than 150-200mm, the strength is almost constant. But this value varies with the kinds of castings or their thickness, corresponding to the size of dendrite arm spacing. The strengths at locations beyond the above-mentioned distance are lower, and the apparent specific gravities are also lower. The strengths of specimens containing defects are under 200MPa. These casting defects are classified into lump, thin and scatter structure defect. While the lump defect reduces both apparent specific gravity and tensile strength, the thin and scatter structure defects reduce the tensile strength but hardly affect the apparent specific gravity. The tensile strength varies almost linearly with the fraction of defect area on the fracture surface. The scatter of the strength of aluminum die castings can be reduced, when they are cast under the conditions that produce defects within a certain small quantity.