Conventional Compaction Research Articles

Using a Complex-Impedance Measuring Instrument to Determine In Situ Soil Unit Weight and Moisture Content

Abstract In situ measurements of soil unit weight and moisture content play a critical role in conventional compaction quality assurance and quality control procedures. Recently, there have been a number of attempts to develop alternative electrically-based test devices that can be used to measure the in situ unit weight and/or moisture content of a compacted soil; these devices are intended to serve as alternatives to more traditional tests such as sand cone, rubber balloon, drive cylinder, or nuclear density gauge tests. The study described in this paper focuses on the use of a relatively new electrically-based in situ soil test device that uses measurements of soil complex impedance, soil capacitance, and soil resistance to infer in situ soil unit weight and moisture content; this device is typically referred to as a complex-impedance measuring instrument (CIMI). This paper provides a detailed explanation of current CIMI operating principles and also describes the utilization of a CIMI for field- and laboratory-based testing. The CIMI used in this study was calibrated and assessed in two field compaction projects in which different silty sands were used for construction. A mold-based calibration approach was developed for building an electrically-based soil model using the CIMI; this approach provides an alternative to field calibration of the device. In order to perform a more complete assessment of the CIMI in a controlled environment, a series of CIMI tests were conducted in a large “field box,” and the resulting in situ measurements of soil unit weight and moisture content made using the CIMI are compared with the results from nuclear density gauge, sand cone, and drive cylinder tests. The advantages and disadvantages of field versus mold calibration of the CIMI are discussed, and side-by-side assessment of the CIMI relative to other conventionally used compaction control tests allows the reader to assess the accuracy of this device.

Application of recycled aggregate porous concrete pile (RAPP) to improve soft ground

In this study, a series of laboratory chamber tests was carried out to evaluate the applicability of a porous concrete pile fabricated with recycled aggregates for soft ground improvement. The recycled aggregate porous concrete pile (RAPP) has been developed to replace natural aggregates and to overcome technical problems associated with the conventional compaction piling systems. The laboratory chamber tests for evaluating the performance of RAPP were carried out with a cylindrical mold of 280 mm in internal diameter and 580 mm in height. A replacement area ratio of 5 % and three different loading steps were applied in the chamber tests. The experimental results of the surface settlement, excess pore pressure and vertical stress distribution versus time were compared with those of the sand compaction pile (SCP) reinforced composite ground under the same experimental condition. In addition, the experimental results were compared with the numerical simulation using ABAQUS. The current study shows that the settlement reduction in the RAPP-reinforced system is significantly enhanced due to load transfer from the soil formation to the RAPP. Furthermore, the comparison of consolidation rates shows that the RAPP can also accelerate the consolidation of soft clay formation because the RAPP behaves as a vertical drain.

Laboratory Assessment of Workability of Asphalt Rubber Hot Mixes Using Warm Mix Technology

Using the waste crumb rubber modified asphalt to pave the road surface could reduce cost and save energy. However，in order to obtain adequate workability, the mixing temperature and compaction temperature of rubberized asphalt binder and its mixture is much higher than those of conventional asphalt mixtures. Warm Mix Asphalt (WMA) is the name given to certain technologies that reduce the production and placement temperatures of asphalt mixes. One of the main benefits advertised is the increased workability at conventional and lower compaction temperatures with the WMA addition. This paper evaluates whether there are any synergy effects of using warm mix technologies and Asphalt Rubber(AR) hot mixes. This paper summarizes a lab research to evaluate the workability of Asphalt Rubber hot mixes containing warm mix technologies. Both asphalt binder and asphalt mixture were evaluated and compared. The research suggests that combining WMA technology with Asphalt Rubber mixtures is a win-win.

Effect of Gel Chemistry on the Machinability of Green SiC Parts Produced by Gelcasting

The growing interesting in the use of silicon carbide in automotive components, biomaterials, energy, among others, which demand the production of parts with complex geometry that are difficult to obtain by conventional compaction techniques, motivates the search for developing new conformation processes. Within this context, this paper investigates the production of pieces of silicon carbide through the gelcasting process and subsequent green machining of these parts. Three systems of monomers were studied: MAM-NVP-MBAM, MAM-PEG (DMA) and MAM-HMAM. The effect of the concentration of monomers, concentration of chemical initiator and the ratio of chain-forming and crosslinker monomers on the cutting force during machining and surface roughness were evaluated. These data are compared with values of flexural strength and hardness of samples produced under the same conditions. Through a statistical analysis it was determined the best formulation for the production of parts of SiC with favorable characteristics of green machining.

Mechanical properties and thermal stability of bulk Cu cold consolidated from atomized powders by high-pressure torsion

It is difficult to densify and consolidate round-shaped metallic powders by conventional compaction techniques because powder interlocking forces are small and the powders easily slip and rotate instead of being plastically deformed and densified. In this paper, atomized Cu (99.5 % purity) powders of round shapes were cold consolidated to bulk specimens by high-pressure torsion (HPT) under 10 GPa to avoid powder slippage by the shape effect. A relative density over 98 %, high tensile strengths of 642 and 570 MPa, and moderate ductility of 7.5 % with thermally stable ultrafine grained structures are achieved after the HPT consolidation process. The specimens HPT processed at RT show higher tensile strength due to more dislocations and finer grain sizes than the specimen processed at 373 K. Higher ductility in the elevated temperature (373 K)-processed specimen than in the RT-processed specimen is attributed to good bonding between particles, decreased dislocation density, and increased grain size.

Strengthening mechanisms in carbon nanotube reinforced bioglass composites

Carbon nanotube reinforced bioglass composites have been successfully synthesized by two comparative sintering techniques, i.e., spark plasma sintering (SPS) and conventional compaction and sinteirng. The composites show improved mechanical properties, with SPS technique substantially better than conventional compact and sintering approach. Using SPS, compared with the 45S5Bioglass matrix, the maximum flexural strength and fracture toughness increased by 159% and 105%, respectively. Enhanced strength and toughness are attributed to the interfacial bonding and bridging effects between the carbon nanotubes and bioglass powders during crack propagations.

Management of an Anterior Tooth with External and Internal Resorption

ABSTRACT Tooth resorption is a condition associated with either a physiologic or a pathologic process resulting in a loss of dentin, cementum, and/or bone. Inflammatory process is initiated when the predentin or precemental layer of the tooth is damaged. Resorption can either be external or internal in form. In order to control the tooth resorption, it is necessary to treat the root canal by removing all the pulp tissue. Due to varied root canal morphology, root canal treatment poses a challenge for the clinician. In such cases a combination of conventional lateral compaction and thermoplasticized gutta percha can enable the three-dimensional obturation of the canal space. This case report describes a nonsurgical mode of management of a tooth having internal and external (surface) resorption. How to cite this article Anilkumar A, Nair KR, Nazar F, Rajendran R. Management of an Anterior Tooth with External and Internal Resorption. Cons Dent Endod J 2017;2(1):32-35.

Improving Quality Control of Hot-Mix Asphalt Paving with Intelligent Compaction Technology

This paper answers whether existing intelligent compaction (IC) technology can be used in a practical way to improve the quality control (QC) process for hot-mix asphalt (HMA) paving projects. Specifically, the paper investigates the use and the benefits of IC technology for tandem drum vibratory rollers used to construct HMA materials. There is a need to improve QC practices for most typical HMA paving operations. This paper identifies and discusses major shortcomings in conventional compaction equipment and current QC practices. The use of IC technology can address these shortcomings and provide innovative QC tools to contractors and agencies. The paper is based on the findings of the Intelligent Compaction Pooled Fund (ICPF) project that included 16 field demonstration projects in 12 participating states. The ICPF projects were actual highway construction projects in which various pavement materials were placed and compacted with both conventional compaction equipment and rollers that were equipped with IC technology from various suppliers. Eight of the projects included placement and compaction of HMA materials. On these projects, IC was used for only a portion of the project. A case study of the Wisconsin project illustrates the benefits that could have been obtained if IC technology and specifications had been used for the entire project from beginning to end.

High Velocity Compaction: Comparison with Conventional Compaction for New Press Development in Hot Cell Pellet Manufacturing

Within the framework of the technological developments for fuel fabrication in hot cell, the compaction of ceramic powders using both static and dynamic processes has been studied as regards the manufacturing of nearly fully dense ceramics with unique microstructures from precursor ceramic powders. High Velocity Compaction (HVC) is a dynamic compaction without shock wave. The objective of this study [24,[25] was to compare the results of shaping between a conventional and a HVC process, both with hydraulic systems providing the impaction. Various inactive alumina powders were tested. Their characteristics after pressing were assessed to show the differences between green and sintered pellets.

Fractal dimension of pore-structure of porous metal materials made by stainless steel powder

Pore-structure is one of important factors affecting the properties of porous metal materials, but it is difficult to describe the complexity of pore-structure exactly. Fractal theory is a very effective method for investigating pore-structure of porous metal materials, which builds a bridge between micro-morphology and macro-performance. In the paper, two kinds of stainless steel powder for different powder images (irregular and spherical shapes) with particle size of 38μm–150μm were used to prepare samples to a preset porosity, which ranged from 20.4% to 45.5%, by conventional compaction technique, and then sintered at 1250°C for 2h in the vacuum. The porosity and microstructure of sintered samples were analyzed using the Archimedes' law and the optical microscope, respectively. In addition, the pore-structure was studied by fractal theory and the fractal dimension was calculated using the box counting method. The results show that the fractal dimension decreases continuously with the increase of magnification, from 1.43 to 1.25 for irregular powder, and the optimal magnification ranges from ×200 to ×500, but it increases gradually with the increase of porosity. Furthermore, the relationships between the fractal dimension and the magnification or porosity can be expressed by the model of D=a0exp−xa1+a2 or D=k2−k1−k21+expθ−k0k3, respectively.

Chiba Scan Delay Fault Testing with Short Test Application Time

Delay fault testing using a scan design facilitating two-pattern testing, called Chiba scan testing, requires a long test application time (TAT) compared with well-known delay fault testing. This paper presents an improved Chiba scan testing with short TAT by providing a test compaction. In addition, it presents a test generation for the Chiba scan testing improved by the proposed compaction. Evaluation shows that, for robust path delay fault testing on ISCAS89/ ADDENDUM benchmark circuits, the TAT of Chiba scan testing with the proposed compaction is, on average, 47% and 21% shorter than that of Chiba scan testing without test compaction and that of enhanced scan testing with the conventional test compaction, respectively. In addition, in many cases, the fault coverage of the proposed testing is higher than that of launch-off-capture (LoC) and launch-off-shift (LoS) testing with the same TAT.

Compaction Experiment on the Newly Designed Warm High Velocity Compaction Equipment

In order to develop high density powder metallurgy forming technology, a new concept combining high velocity compaction and warm compaction called warm high velocity compaction (WHVC) was presented. A new warm high velocity compaction forming equipment which adopts gravitational potential energy instead of hydraulic cylinder as hammer driver was designed. By means of the newly developed equipment, a preliminary study on warm high velocity compaction was performed. 316L stainless powder compacts with green density of 7.47 g/cm3 were obtained; the density is much higher than those prepared by conventional high velocity compaction. These results demonstrate that the newly designed equipment can basically meet the demand of warm high velocity compaction and the new forming method is superior to the conventional high velocity compaction. In addition, Densification mechanism of WHVC was also discussed.

High-velocity compaction and conventional compaction of metallic powders; comparison of process parameters and green compact properties

High-velocity compaction (HVC) has been used for some years now with commercially available high-energy hydraulic presses. Compact densification is achieved in less than 0.01 s, shorter than with a conventional process (about 1 s) but longer than with explosive compaction (0.001 s). Powders are compacted by means of an adjustable energy instead of force or displacement. This work presents a comparison between conventional compaction (CC) and HVC using an industrial hydraulic press (18 kJ) and a laboratory press (380 J). The velocity of the hammer producing the impact is therefore restricted to 10 m/s. Six powders were compacted using the HVC process and the conventional die compaction process. Differences and similarities are examined considering process characteristics (punch forces, ejection force, and tooling strength) and the characteristics of green compacts (densities, dimensions, and cohesion).

Spontaneous manufacturing: alumina 128-well plates made by droplet drying

The radial flow inherent in the drying of a sessile drop has inspired the idea of preparing ceramic microwells from deposition of droplets of ceramic suspension. In this way, the shape of each well is created spontaneously without the need for a forming operation. A rectangular plate of alumina powder was made by conventional compaction and cylindrical discs were printed and sintered on its upper surface. A suspension containing the same alumina powder was printed on these discs to form droplets which were left to dry. As they did so, the powder spontaneously assembled at the periphery to form microwells. After sintering, a 128-well plate was prepared which is suitable for high temperature combinatorial experiments.

Magnetic packing of graphite encapsulated nickel nanoparticles

Graphite encapsulated metal nanoparticles (GEM) have a very special core-and-shell spherical structure (5–100 nm in diameter). The core is metal nanoparticle and the shell consists of several to over ten layers of graphitic sheets. Because the outer shell protects the inner metal nanoparticles, the materials remain stable in strong acid as well as at high temperature in an oxygen-free environment. Nanoparticles are usually very difficult to compress; with the ferromagnetic metal core of Ni-GEM, one would expect its compaction to be even more difficult. In this work, however, a new and simple magnetic packing method was developed, by which >90% dense Ni-GEM bulk can be produced without going through any of the conventional compaction procedures. The as-made GEM powder will first be purified via an acid-bath to remove any poorly encapsulated Ni particles. Then the GEM is dispersed in methanol, and subjected to a strong magnetic field. After the entire amount of methanol has been evaporated, many small pieces of high-density bulk GEM material can be obtained. Preliminary results show there are several important factors which affect the final packing density of bulk Ni-GEM: the type of dispersant, the dispersant's evaporation rate and the magnetic field intensity.

Comparative research on high-velocity compaction and conventional rigid die compaction

Experiments were carried out with different apparatus to compact electrolytic copper powders at distinct loading speeds. It appears that green densities of compacts prepared by HVC out-number that by conventional compaction by one percent. Compacts by quasi-static compaction are almost as dense as those by HVC under comparable peak pressure. The relationship between green compact density and peak pressure accords with Hang Pei-yun formula well. Spring-backs of HVC compacts are far smaller than those of conventional compaction and quasi-static compaction. HVC compacts are harder than compacts by conventional compaction and quasi-static compaction when they have the same density.

La métallurgie des poudres appliquée aux multimatériaux

Plusieurs laboratoires et centres techniques ont commencé à travailler sur la possibilité de réaliser des composés multimatériaux via la Métallurgie des Poudres. Dans un tel cas, ce procédé permet d'éviter le problème de l'assemblage et d'obtenir une production aux cotes. Les compressions dynamique (CGV) et conventionnelle sont deux voies possibles qui pourront être comparées grâce à une presse de laboratoire instrumentée pour l'analyse des phénomènes. Pour certaines poudres, la CGV permet d'améliorer les propriétés à vert et de modifier favorablement les conditions de frittage. La compression est suivie d'un frittage conventionnel. Différents types de poudres (poudres métalliques, poudres dures mais également des poudres céramiques) sont utilisés dans ce projet permettant ainsi de proposer de nombreuses applications. Cette présentation montre les premiers résultats obtenus par le groupe de recherche.

Using relations between stress and fluid pressure for improved compaction modelling in flow simulation and increased efficiency in coupled rock mechanics simulation

ABSTRACT The conventional compaction model used in reservoir simulators defines compaction as a function of fluid pressure, whereas, in reality, it is a function of effective stress. The interrelationship between fluid pressure, effective stress and reservoir parameters (materials distribution, geometry, production scheme) is investigated. By modifying the conventional concept of flow simulator compaction a predictor is constructed for the rock mechanics computations in a coupled flow–rock mechanics simulation. This predictor reduces the time to converge the stress computations by reducing or eliminating the number of pore volume iterations in the coupling scheme. Overall computing time is thereby reduced considerably, while maintaining accuracy in the stress computations. Additionally, the compaction state in the flow simulator will be more accurate than in a conventional iterative coupling scheme.

Use of in Situ Tests in Compaction Control of a Bottom Ash Embankment

Since 1994, the Indiana Department of Transportation has constructed numerous recycled materials projects that use bottom ash, fly ash, foundry sand, crushed glass, and tire shreds in transportation facilities. All these projects were constructed in accordance with procedural specifications based on conventional compaction control tests such as the nuclear gauge. However, the nuclear gauge does not give accurate density and moisture content results because of the presence of numerous elements in recycled materials. In addition, sand cone tests are cumbersome and time-consuming. There is a need to develop criteria for in situ test methods such as the dynamic cone penetration test and lightweight deflectometer (LWD) testing. Once an initial criterion is established, criteria for compaction control of similar recycled materials can be developed. In a study, a test pad using coal ash was constructed with a combination of roller passes. On the basis of the results of dynamic cone penetration and LWD tests conducted in the test pad, in conjunction with a combination of roller passes, the criteria for compaction control of bottom ash was provided for the construction of the remaining 11-m-high embankment. The subsequent construction monitoring and postconstruction evaluation of the bottom ash embankment revealed that the criteria are very effective.

The Improvement of Permeability and Strength in Soft Magnetic Composites Motor Core Using Spark Plasma Sintering Process

The practical uses of soft magnetic composite(SMC) for an electrical motor is presented in this paper. SMC allows obtaining improved stator and core shapes as well as totally new design concepts such as claw pole motor. However, a major disadvantage of soft magnetic composites was their weak strength. In this study, spark plasma sintering (SPS) was utilized to improve the strength of SMC. Advantages of the SPS process over other conventional sintering process are the faster heating and cooling rates ensured and higher pressure applied during the sintering procedure. This allows obtaining high strength products in short periods of time to meet with industrial application without insulation destruction. This paper introduces the development of high strength soft magnetic composite motor core and examples of practical application for industries. The result showed that the SPS process increased the fracture strength, about 1.3 to 1.7 times, of SMC compare to the conventional compaction. Also we derive method to reduce the iron loss in the SPS sintering process using control forming temperature. As the forming temperature decreased from 500°C to 300°C, reduction of iron-loss was obtained from 192W/kg to 21W/kg by using SPS sintering process. Moreover, with increased the SPS sintering process pressure value from 250MPa to 800MPa which is the conventional compaction condition and decreased forming temperature to 200°C, iron-loss was measured. The results showed that iron-loss was obtained 11.42W/kg and it was similar value of conventional compaction results.