Lower Void Ratio Research Articles

Exploring alkali-source, pore-filling and cementation damage effects in cemented clay with typical industrial waste binders

Various industrial waste binders (IWBs) are being recycled in soil stabilization to save cement consumption. However, the coupled effects brought out by combined IWBs on stabilized soils are still unclear. IWBs are categorized into two typical categories (IWB-A and IWB-B) referring to their chemical role in this study. The alkali-source effect, pore-filling effect and cementation damage effect by IWBs in soil stabilization are explored. A series of mechanical and microscopic tests is performed on stabilized clay with different proportions of IWB-A and IWB-B. Moreover, initial water contents and cement contents of cement-stabilized clay are varied to examine the evolution of coupled effect with void ratio and cementation level. The results indicate that the alkali-source effect strengthens the cementation bonds and increases the early strength by 0.5–1.3 times, whereas the pore-filling effect improves the microfabric especially for the specimen with a large void ratio. The alkali-source effect increases soil cohesion cu at the pre-yield stage, and the pore-filling effect increases frictional angle φu at the post-yield stage. The cementation damage effect is remarkable at a low void ratio, which may result in many extruded pores among soil aggregates. The strength evolution with IWB proportions can be well stimulated by considering the coupled alkali-source effect, pore-filling effect and cementation damage effect. The optimal proportion of IWBs corresponds to an optimal combination of coupled effect.

Investigating the impact of different solder alloy materials during laser soldering process

PurposeThis study aims to investigate the influence of different solder alloy materials on passive devices during laser soldering process. Solder alloy material has been found to significantly influence the solder joint’s quality, such as void formation that can lead to cracks, filling time that affects productivity and fillet shape that determines the solder joint’s reliability.Design/methodology/approachFinite volume method (FVM)-based simulation that was validated using real laser soldering experiment is used to evaluate the effect of various solder alloy materials, including SAC305, SAC387, SAC396 and SAC405 in laser soldering. These solders are commonly used to assemble the pin-through hole (PTH) capacitor onto the printed circuit board.FindingsThe simulation results show how the void ratio, filling time and flow characteristics of different solder alloy materials affect the quality of the solder joint. The optimal solder alloy is SAC396 due to its low void ratio of 1.95%, fastest filling time (1.3 s) to fill a 98% PTH barrel and excellent flow characteristics. The results give the ideal setting for the parameters that can increase the effectiveness of the laser soldering process, which include reducing filling time from 2.2 s to less than 1.5 s while maintaining a high-quality solder joint with a void ratio of less than 2%. Industries that emphasize reliable soldering and effective joint formation gain the advantage of minimal occurrence of void formation, quick filling time and exceptional flowability offered by this solution.Practical implicationsThis research is expected not only to improve solder joint reliability but also to drive advancements in laser soldering technology, supporting the development of efficient and reliable microelectronics assembly processes for future electronic devices. The optimized laser soldering material will enable the production of superior passive devices, meeting the growing demands of the electronics market for smaller, high-performance electronic products.Originality/valueThe comparison of different solder alloy materials for PTH capacitor assembly during the laser soldering process has not been reported to date. Additionally, volume of fluid numerical analysis of the quality and reliability of different solder alloy joints has never been conducted on real PTH capacitor assemblies.

Development of Cu-Nb Reinforced Nb3Sn Wires Appropriate for Large Multi-Stage Stranded Cables With Short-Pitch Twisting and Low-Void Ratio

The strength of the conventional Cu/Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn wires may be too low to be applied to much larger cable-in-conduit (CIC) conductors with the multi-stranded cable structure of short-pitch twisting and low-void ratio applied for ITER-CS conductors. In this study, the Nb-rod-method Cu-Nb reinforced ITER-type Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn wire was developed by using a bronze-process not only to realize superior superconducting properties under high electromagnetic stresses but also to mitigate damage to the superconducting wires during the cable manufacturing process. The critical current properties of the Cu-Nb/Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn wire were significantly higher performance under both tensile stress and transverse compression stress compared to a conventional non-reinforced Cu/Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn wire. The Cu-Nb reinforcement had no detrimental effect on the AC losses of the wire. The trial production of short-pitch sub-cables was conducted, and it was confirmed that the Cu-Nb/Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn wires can improve the manufacturability of multi-stage stranded cables co-twisted with copper wires.

Прочностные характеристики массива мелкозернистого песчаного грунта с вертикальными армоэлементами из крупного заполнителя

This work's main objective was to increase the value of the coefficient of friction between soil grains in the test specimen by adding coarse gravel columns to the fine, sandy soil. In this regard, it was determined that a soil's lowest void ratio should be used as a measuring criterion because it matches the crucial requirement of an independent friction angle from soil gradation, all of the results above were calculated using the outcomes of a laboratory test method. Pressure addition was used to determine the relationships between a mixture with a low void ratio and the critical state or high coefficient of friction angles. Determining the strength characteristics of sand-gravel mixtures may be helped by the linkages. The riverbanks of the Tigris, which had previously been subject to similar cracks and collapses, served as the location for the collection of samples for the purpose of this research.&#x0D; The completion of the study and examination, it was discovered that the soil is composed of river sediments and that it has the potential to be categorized as soil that is constructed of fine sand. It is generally acknowledged that shear loads are a significant element that contributed to the demise of numerous riverbanks. In this particular field of research, a variety of coarse aggregate column widths and aggregate sizes used to increase the friction angle of soil are investigated via direct shear testing.&#x0D; When analyzing the qualities of soil, the minimal void ratio is important, Particle size distributions and particle shapes influence their relationship to compressive characteristics, permeability, and shear strength of the soil. While previous studies have modeled the minimal void ratio in terms of the impact of particle size distributions, they have largely disregarded the role that particle shape might play in this parameter. This work examines the effects of three different sizes of coarse aggregate on the minimal void ratio with respect to particle size distributions. Experiments have shown that when the number of fine particles increased the minimum void ratio reduced. The more irregularity there was in the particle shapes, the more difficult it was for particles to make touch with one another, and the more space there was between them. Diagrams depicting the connection between shear strength, angle of friction, and particle size distribution were created from experimental data.

Gradation design and performance evaluation of modified asphalt mixture for bridge asphalt plug joint design

Although the Asphalt Plug Joint (APJ) has been developed for half a century to overcome the maintenance issues in traditional bridges, its shortcomings, such as short service life and poor deformation capacity, have not been overcome. There are currently no adequate specifications in place to guide the material design and performance evaluation of APJs. Therefore, this study proposes a suitable design method for asphalt mixtures based on the mechanical characteristics and performance requirements of APJ. According to the proposed mixture type, the influence of gradation type on the bonding strength, shear strength, and tensile strength of the APJ mixture is explored mainly based on direct shear test, direct tensile test, and meso-structure analysis. In addition, the effect of fiber type on improving the performance of mixture and the influence of temperature on the performance of the mixture are discussed. The test results show that it is recommended to use a skeleton-filled asphalt mixture with a lower void ratio, more fine aggregates, more mineral powder, and more asphalt in the APJ. Similarly, modified asphalt with good high and low temperature performance should be selected, and an appropriate amount of reinforcing fibers, such as polyacrylonitrile fiber and basalt fiber, should be added to the asphalt mixture.

Pore structure effects on the water retention behaviour of a compacted silty sand soil subjected to drying-wetting cycles

Most of the previous studies on the effects of pore structure on soil water retention behaviour are limited to a single drying and wetting cycle. This study evaluated the effects of pore structure on water retention behaviour for specimens prepared at different pore structures of similar density, subjected to drying-wetting cycles. Specimens were compacted at two density states equivalent to loosely compacted fill slopes (80% relative compaction, e = 0.78), and densely compacted slopes or subgrade compaction specifications (95% relative compaction, e = 0.50) at different water contents on the wet side (20%) and dry side (10%) of the optimum water content. The results show that loosely compacted specimens prepared on the wet side have a lower water retention ability due to the larger formed macropores. They also show a significantly higher degree of hysteresis which decreases with drying and wetting cycles. For loosely compacted specimens, there is a higher increase in water retention ability with cycles for specimens prepared on the dry side, due to more drying and wetting-induced pore evolution and volumetric changes. Increasing compaction density results in a higher water retention ability but reduces the number of cycles needed to achieve water retention equilibrium with drying-wetting cycles, subsequently behaving as scanning curves. This is attributed to the less pore evolution and smaller volumetric strain at lower void ratios. Pore structure effects on water retention behaviour subjected to drying-wetting cycles should be considered in civil engineering designs for earth structures, such as loosely compacted fill materials.

X-Ray microtomography of mercury intruded compacted clay: An insight into the geometry of macropores

Soil properties, such as wetting collapse behaviour and permeability, are strongly correlated to the soil microstructure. To date, several techniques including mercury intrusion porosimetry (MIP), can be used to characterize the microstructure of soil, but all techniques have their own limitations. In this study, the features of mercury that penetrated and has been entrapped in the pore network of the specimens through MIP testing were investigated by X-Ray microtomography (X-μCT), in order to give an insight into the geometry of macropores and possible ink-bottle geometry. Two conditions of water content and density were selected for the compacted Maryland clay. The distribution and geometry features of mercury entrapped in the microstructure after MIP were characterized and pore size distributions were also reconstructed. The results suggest that, for the two conditions studied in this paper, macropores were evenly distributed within the specimens, and most of them with a non-spherical shape, and with aspect ratio (ratio between the maximum and minimum thickness along a given segment) smaller than three. Different dominant entrance pore size of macropore was obtained from MIP and X-μCT, due to the specific experimental protocol used in tests and the effect of ink-bottle geometry. Only the large pore bodies with high aspect ratio were imaged in X-μCT, due to the extrusion of mercury during the process of depressurization and subsequent sample preparation for X- μCT. But entire pore space was accessible in MIP. The difference in dominant entrance pore size was more significant for specimens with lower void ratio due to a more pronounced aspect ratio.

The role of creep in geopressure development

This study developed a one-dimensional numerical model of sedimentation and compaction based on the equivalent isochrone framework to investigate the impact of creep on geopressure during burial. In this framework, the void ratio is a function of effective stress and strain rate; the change in void ratio is the same with each order of magnitude decrease in strain rate at a constant effective stress. We simulated lower void ratio and higher overpressure when creep was included compared to cases where no creep was present and void ratio is only a function of effective stress. Creep causes apparent overconsolidation. The apparent overconsolidation ratio is used to quantify the magnitude of creep; this is the vertical distance from the normal compression curve in a void ratio v. effective stress plot. The magnitude of creep depends on the loading rate, and increases with depth at sites with low sedimentation rates. These findings bridge the gap between laboratory and field observations on rock compression behaviours. For example, it provides one explanation why laboratory-derived compression curves have a higher void ratio at a given effective stress. In addition, it suggests under what conditions the rock will behave elastically. Thematic collection: This article is part of the Geopressure collection available at: https://www.lyellcollection.org/cc/geopressure

Effect of ocean environmental particles on compressibility, electrical resistivity, and stiffness characteristics of mixtures

The influence of diatoms, which have distinct physico-chemical characteristics, is a key factor in the investigation of deep-sea sediments. The objective of this study was to investigate the compressibility, electrical resistivity, and stiffness of sand–silt–diatom mixtures performing oedometer tests. The specimens were prepared by mixing fines containing silts and diatoms into sand, and the fines contents were 0%, 10%, 20%, and 30% in weight (FC00, FC10, FC20, and FC30). The oedometer test was carried out from 5 to 640 kPa, and the electrical resistivity, shear wave velocity, and compressional wave velocity were obtained during loading and unloading. The test results show that the electrical resistivity and compressional wave velocity have transitional behavior at FC10 owing to the dominant effect of fines. The shear wave velocity decreases with an increase in fines contents despite a lower void ratio due to the fines. Moreover, the equivalent bulk modulus of the mineral from back-calculation also exhibits a transition at FC10. However, both compression indices from the measured data and the asymptotically-sound compaction model equation exhibit the transition at FC20. In addition, FC20 is located on the boundary between the sand-dominant and transitional mixtures in the triangular chart of ternary mixtures. The results suggest that the transitional fines content of mechanical behavior changes at the points of large and small strains.

Comparing carbide sludge-ground granulated blastfurnace slag and ordinary Portland cement: Different findings from binder paste and stabilized clay slurry

This experimental study investigated the use of combined industry by-products, carbide sludge (CS) and ground granulated blast-furnace slag (GGBS), to replace ordinary Portland cement (OPC) for the stabilization of clay slurry, aiming to increase the stabilization efficacy, reduce the cost, and mitigate the environmental impacts associated with OPC production and disposal of industrial by-products. To better understand the stabilization mechanisms, properties of CS-GGBS and OPC stabilized clay slurry are systematically evaluated and compared. Test results indicate that the unconfined compressive strength (UCS) of the optimum CS-GGBS-stabilized clay slurry is 2–4 times that of the corresponding OPC-stabilized clay slurry. However, the strength of OPC paste is 1.3–1.4 times that of the optimum CS-GGBS paste. Due to the ultra-high water content and the active clay minerals, larger amounts of Ca(OH)2 are required to reach the same pH of pore water in stabilized clay slurry specimens than in the paste. This is responsible for the greater optimum CS/(CS + GGBS) ratio in the stabilized clay slurry than in the paste. OPC hydrates much faster and consumes more water than CS-GGBS during specimen preparation, resulting in a much lower void ratio and higher strength of OPC paste. For the stabilized clay slurry, the binder contents are very low and the water-to-binder ratio is hence very high, and thus the effect of binder hydration rate on the void ratio is insignificant. The remarkably different strength discrepancy between both types of stabilized clay slurry is not attributed to the slightly different void ratio, but due to the significantly different microstructures formed in the stabilized materials. The findings in this study contribute to a deep insight into the strength development of stabilized clay-slurry type dredged material.

On compression behavior and particle breakage of carbonate silty sands

Carbonate soils are high in compressibility and low in particle strength, and therefore need special treatment for many geotechnical applications. This paper presents comprehensive one-dimensional compression tests to investigate the compression behavior and particle breakage of carbonate soils with various initial particle size distributions (PSDs) and a wide range of initial void ratios at a high effective vertical stress of 32 MPa. A clear shape transition in terms of the void ratio against effective vertical stress was observed with varying silt fraction and void ratio. The deformation mechanism for the samples with less silt fraction and higher void ratio is mainly dominated by the particle-breakage-induced unlocking effect. Samples with more silt fraction and lower void ratio will experience less particle breakage and their deformation mechanism is mainly attributed to interparticle locking effect. A ‘transitional’ mode of behavior without a unique normal compression line was identified for the samples with silt fraction ranging from 1.6% to 33%. It was also found that carbonate soil samples with both ‘transitional’ and ‘non-transitional’ modes of compression behavior may both experience considerable amount of particle breakage and show different trends in the evolution of particle shape.

Effect of Heat Injection through a Vertical Drain on Clay Consolidation

Temperature change affects the consolidation behavior of soft clay. An increase in temperature in soft clay leads to the dissipation of excess pore water pressure and the decrease of volume. This temperature-induced consolidation can be utilized as a novel approach to improve soft ground. In this study, in order to investigate the effect of heat injection through a vertical drain on soft ground consolidation, a test device was designed to install different-sized sand drains that enabled heat injection and temperature control of a vertical drain. Using the device, a series of consolidation tests was performed with varying heat injection and varying diameter of the vertical drain. During consolidation, vertical settlement and temperature at various locations in the ground were measured. After each consolidation test, the spatial distribution of void ratio in the ground was estimated. Test results showed that heat injection increased the radial temperature of the ground, and the increasing diameter of sand drain with an internal heat source also expanded the heating area in the ground. Furthermore, the larger diameter sand drain led to greater final settlement and lower void ratio.

Evaluation of the hydraulic conductivity for MSW using pilot plant test- A case study of Baghdad city/Iraq

The hydraulic properties of municipal solid waste (MSW) have been regarded as core factors affecting landfills’ flows. To successfully design and applied, information on the conductivity of MSW is required. A laboratory examination of MSW’s hydraulic conductivity in Baghdad City is presented in this study and assesses the influence of waste compaction on hydraulic conductivity parameter. A hydraulic conductivity test was carried out in a laboratory-scale cell using three mixtures of fresh shredded MSW samples ‘SAM1’, ‘SAM2’ and ‘SAM3’ collected from the households Baghdad City. The saturated vertical hydraulic conductivity was quantified according to different types of compactions using a falling head test. A clear trend of decreasing hydraulic conductivity with increasing compaction degree was highlighted after the monitoring process, reflecting the impact of varying waste densities and fine particles’ movement in the column. This experiment shows that the average hydraulic conductivity values at 50, 70, and 90 degrees of compaction were 1.23×10-4 m/s, 0.96×10-4 m/s, and 2.55×10-5 m/s, respectively. The results distinctly showed that the MSW’s hydraulic conductivity could be significantly affected by vertical compaction that is fundamentally attributed to accretion in density resulting in the low void ratio.

The role of interfaces in the bentonite barrier of a nuclear waste repository on gas transport

The FEBEX in situ test provided bentonite samples that had been submitted to the conditions of the engineered barrier of a nuclear waste repository for 18 years. These samples can be considered quite evolved from the microstructural point of view (aged, matured) when compared with samples prepared in the laboratory under shorter and more usual time scales. The barrier, composed of bentonite blocks, was hydrated with granitic groundwater under natural conditions while it was submitted to the thermal gradient generated by a heater mimicking the waste canister. Some of the samples were drilled between two bentonite blocks, therefore they were crossed along by an interface. The gas permeability of samples with and without interface was tested in the laboratory under different triaxial boundary conditions. Samples with an interface drilled in the inner part of the barrier (i.e. closer to the heater and consequently drier) had higher gas permeability than samples of similar accessible void ratio (related to dry density and water content) with no interface, and it was necessary to apply higher confining pressures to reduce or suppress gas flow in them. Both observations point to the interface as a preferential pathway for gas flow in this kind of samples. In contrast, wetter samples drilled along interfaces of the external part of the barrier (which had very low accessible void ratio, because of the high saturation), had permeabilities similar to those corresponding to the same accessible void ratio in the reference, untreated bentonite. This would prove the healing of the interfaces between blocks as a result of full saturation. The importance of the testing boundary conditions, particularly with respect to confinement, on gas transport processes was also highlighted. • Research related to engineered barrier of nuclear waste repository. • Role of interfaces only relevant for low degree of saturation. • Contribution of interfaces to gas transport decreases with confining pressure. • Complete healing of interfaces after saturation.

Investigation of pile penetration in calcareous soft rock using X-ray computed tomography

Penetration of open- and closed-ended model piles into intact chalk, a soft calcareous rock, was investigated using microfocus X-ray computed tomography (XCT). Three-dimensional images of the specimens showed that the piles crushed and densified the chalk in their path, creating a crushed chalk annulus around the shaft, a region of compressed destructured chalk below the tip, and fractures across cemented regions of the specimen. Laser-diffraction particle-size analyses of the crushed chalk annulus after exhumation showed limited difference with laboratory-remoulded chalk, which suggested thorough de-cementation. Installation stresses and XCT-derived densities were paired using a simplified cylindrical cavity expansion solution to estimate effective radial stress–void ratio states at the pile tip during penetration. More complex numerical solutions could not be applied using the available data. This approach posed significant problems, as it could not suitably incorporate hardening and non-linear stiffness behaviours of chalk during pile penetration, nor account for the creation of discontinuities. However, effective radial stress–void ratio estimates were found to converge with the reconstituted critical state line of the material at high stresses and low void ratios. This partially supported the use of a critical state framework to characterise pile penetration in chalk, as proposed in recent literature.

Time-dependent collapse potential of unsaturated collapsible gypseous soils

PurposeThis study aims to predict the volume changes and collapse potential (CP) associated with the changes in soil suction by using the pressure cell and the effect of initial load on soil suction. Three types of gypseous soils have been experimented in this study, sandy gypseous soil from different parts of Iraq. A series of collapse tests were carried out using the oedometer device [single oedometer test (SOT) and double oedometer test (DOT)]. In addition, large-scale model with soil dimensions 700 × 700 × 600 mm was used to show the effect of water content changes in different relations (collapse with time, stress with time, suction with time, etc.).Design/methodology/approachA series of collapse tests were carried out using the oedometer device (SOT and DOT). In addition, a large-scale model with soil dimensions 700 × 700 × 600 mm was used to show the effect of water content changes in different relations (collapse with time, stress with time, suction with time, etc.).FindingsThe CP increases with the increasing of the void ratio for each soil. For each soil, the CP decreased when the initial degree of saturation increased. Kerbala soil with gypsum content (30%) revealed collapse value higher than Tikrit soil with gypsum content (55%) under the same initial conditions of water content and density, this is because the higher the Cu value of Kerbala soil is, the more well-graded the soil will be. Upon wetting, the smaller particles or fractions of the well-graded soil tend to fill in the existing voids, resulting in a lower void ratio as compared to the poorly graded one. Consequently, soils with high Cu value tend to collapse more than poorly graded ones. The compressibility of the soil is low when loaded under unsaturated condition, the CP for samples tested in the DOTs under stress level 800 kPa are greater than those obtained from collapse test at a stress level of 200 kPa.Originality/valueThe initial value of suction for all soils increases with initial water content decreases.

Effects of net normal stress on hydro-mechanical behaviour of a kaolinite clay soil under different suction paths

Hydro-mechanical behaviour of unsaturated soils has been extensively reported in the literature. However, the effects of net normal stress on soil behaviour under different suction paths have not been addressed. Therefore, in this study, the shear behaviour of a kaolinite clay soil subjected to drying or wetting prior to shearing was investigated by suction-controlled direct shear tests. It was found out that net normal stress suppresses both irreversible volume contraction and decrease in degree of saturation. The magnitude of irreversible volume contraction and the size of hydraulic hysteresis after drying–wetting decreased with the net normal stress. Soil specimens experiencing drying–wetting had lower degree of saturation, and thus generally exhibited lower residual shear strength due to the lower average skeleton stress as compared with those specimens experiencing only drying. It was also found out that, at (σv − σa) = 50 kPa, peak shear strength of specimens experiencing drying–wetting was generally higher than that experiencing only drying, since the contribution to peak shear strength made by lower void ratio might be dominant over the reduction of peak shear strength caused by lower degree of saturation. However, the contrary effect of suction path on peak shear strength was observed at (σv − σa) = 100 and 200 kPa. The peak shear strength of soil specimens experiencing drying–wetting was generally lower, because they had lower degree of saturation and hence lower average skeleton stress at the same net normal stress and the same suction as compared with those experiencing only drying. Furthermore, as compared with those experiencing only drying, soil specimens experiencing drying–wetting exhibited smaller stronger strain-softening and stiffer stress–strain relations, larger shear-induced volume dilation (or less contraction), and more obvious trend of water absorption during shearing at various net normal stresses. Regarding peak shear strength parameters, soil specimens experiencing drying–wetting showed higher cohesion, but lower friction angle than those experiencing only drying.

Fabrication of Highly Reliable Joint Based on Cu/Ni/Sn Double-Layer Powder for High Temperature Application

Abstract A highly reliable three-dimensional network structure joint was fabricated based on Cu/Ni/Sn powder with double-layer coatings and transient liquid phase bonding (TLPB) technology for high temperature application. The Cu/Ni/Sn joint is characterized by Cu metal particles embedded in the matrix of (Cu,Ni)6Sn5/Ni3Sn4 intermetallic compounds (IMCs), with a low void ratio, and can be reflowed at low temperatures (&amp;lt;260°C), but it can reliably work at a high temperature up to 415°C. Cu/Ni/Sn double-layer powders with different Sn layer and Ni layer thickness were was fabricated and compressed as preform used for TLPB joint bonding. The microstructure and phase composition evolution for Cu/Sn and Cu/Ni/Sn systems during reflow and aging were comparatively studied. Two kinds of interfacial structure designs were made, and corresponding interfacial microscopic morphology was analyzed and compared under once and twice reflow soldering processes. The results indicated that the Sn-coating layer was completely consumed to form (Cu,Ni)6Sn5/Ni3Sn4 IMCs, and the Cu/Ni/Sn joint had a lower void ratio and a higher shear strength than those of Cu/Sn. The mechanism of the Ni-coating layer inhibiting phase transformation was studied. The high reliable three-dimensional network structure joint based on Cu/Ni/Sn double-layer powder was fabricated for high temperature application.

Effect of Coarse Aggregate Columns on Angle of Friction in Fine Sandy Soil

Abstract: the study adopted samples from Tigris river shoulders ,which has been subjected to such collapses and cracks. After testing and investigation it was found the soil is formed from river deposits , which can be classified as fine sand soil . It is known that many of the collapses that occurs in the sides of rivers are due to the influence of shear forces . A different of diameters coarse aggregates columns and aggregates sizes used in this study are tested by direct shear test.&#x0D; The main objective of this research to increase the coefficient of friction between the soil particles in the test specimen by adding the coarse aggregate columns to the fine sand soil, In this regard the least void ratio was found as a beneficial index that relates with critical state of friction angle independent on soil gradation. The relations between critical state or high friction angles of the mixture with lower void ratio were determined as a function of addition pressure. The relationships could be useful to determination the strength parameters of (sand gravel mixtures).

Properties of Modified High Permeable Concrete with a Crumb Rubber

Background: High permeable concrete is designed with high porosity, which allows water to pass through it. By considering this ability, it has been widely used for various applications including high permeable road pavement. However, to fully adopt highly permeable road pavement technology is challenging due to high cost and maintenance, besides the present engineers and contractors have insufficient expertise and experience with this technology. Henceforth, the high porosity property is highly favorable for road curb applications especially in the tropical region like Malaysia with high rainfall intensity. Objective: This paper aimed to determine the properties of the concrete experimentally, and propose the optimum mix design of high permeable concrete for road curb. Methods: The flow value and setting time of the cement paste were investigated. Next, the effects of the modified high permeable concrete with varying amount of crumb rubber on compressive strength, permeability and void ratio were also investigated. Results and Conclusion: Results have revealed that the workability of the cement paste increases when the water-binder ratio and the amount of fly ash increase. Meanwhile, an increasing amount of cement ratio and crumb rubber lowers the flow value and consequently leads to lower void ratio and permeability. Besides, it has been found that the higher the compressive strength, the lower the void ratio and permeability of the concrete. The research findings support that using an optimum amount of cement replacement with crumb rubber as an additive may increase the performance a high permeable concrete. Herein, the results indicate that the mix design of the concrete studied has the potential to be applied onto the road curb.