Typical Base Material Research Articles

A Comparative Study of Cement-Treated Sub-Base and Granular Sub-Base

Abstract: It's no secret that countries around the world are fast progressing, and the infrastructure sector plays a critical role in this process. The infrastructure sector is heavily dependent on transportation. Compared to rivers, trains, airlines, and other modes of transportation, the majority of countries rely on roads and highways for transportation of all types. Crushed rock and murrum are common subbase materials for road construction in underdeveloped nations. In many locations, these materials are scarce and difficult to obtain. Fast transportation and conveyance are a top priority for India's Ministry of Road Transport and Highways (MoRTH). As a result, there is an enormous demand for building materials. The expense of producing the base layer material used in pavements, including as drilling, blasting, crushing, and transporting, makes it an expensive choice. However, when subjected to high traffic and/or strong weather, this material does not hold up. In addition, it is difficult to find in urban regions. Among the topics covered in this research are, the strength parameters of the road, total cost of construction and the time required for its construction. Comparative study of CTSB and GSB is explained in this paper. As a result, this material saves on construction costs by reducing the thickness of the crust. The Unconfined compressive strength, California bearing ratio of the cement-treated basis and sub-base is tested and results are obtained. It demonstrates that this material has superior strength and performance than that of typical materials when compared to those requirements. The CTSB methods saved the most money on construction costs of road, as evidenced by the findings. Using cement-treated foundation and sub-base instead of typical base material for road construction is shown in this paper. Keywords: Cement Treated Sub base (CTSB), Granular Sub-Base (GSB), California Bearing Ratio, Unconfined compressive Strength, Performance Analysis.

Qualification & testing of joining development for DEMO limiter component

A development plan for validation of functional principles is defined to support the challenges of mock-up manufacturing and testing. It is aimed to develop the process and infrastructure for qualifying fusion components for the limiters in the European DEMO. The limiters are components that define the plasma boundary by direct contact during normal and off normal transient events and thus they protect the First Wall of the Breeding Blanket System from extreme heat fluxes during these events. Within this framework, the joints play an important role for making feasible the combination of dissimilar materials required for the plasma facing components (PFCs) by providing a compliant interlayer. The main limiter PFC functionality is to act as thermal barrier, therefore the materials combination shall be able to support the thermal gradient between the high heat flux (HHF) from the plasma and the heat sink. The primary aim of the PFC is to ensure the structural integrity of the heat sink of the PFC (to prevent in-vessel loss of coolant accident), as it is foreseen that during the off-normal transients the PFC surface may melt or evaporate. Minimizing the large deformation and guaranteeing the strength and fatigue behaviour of the joints is required to achieve this.Therefore, a testing programme for joining development and qualification based on brazing technology is performed. It is focused on joint assessment between representative filler metals (OB1025TM, OB950TM, PB950TM, NBLMTM & H-BronzeTM) from the different families in the market and the chemical compatibility, capillarity flow and spreadability on the typical base materials used for PFC (laser powder bed fusion additive manufactured W-6%Ta, W, P91, OFHC Copper, CuCrZr). The main results show good wetting of the gold-copper alloy (OB1025TM) with all the base materials. It allows to progress with the integration of a PFC to create the process and infrastructure for optimizing the design of critical joints. NBLMTM seems to be an interesting filler for materials with high melting temperature as tungsten and P91 and OB950TM presents acceptable wetting condition with the base materials. PB950TM is rejected because the excess of wetting on all the base materials.

Arc PVD (Cr,Al,Mo)N and (Cr,Al,Cu)N coatings for mobility applications

Efficiency during operation is besides reliability and cost effective production one of the most important demands on machines and components. Especially within the automotive sector, components need to fulfill these requirements. Since the demands for high efficiency and reliability cannot be met solely by typical base materials such as case hardened steels, physical vapor deposition (PVD) coatings for the application on highly loaded components gain increasing importance. A possible approach to reduce friction and wear in tribological systems are triboactive and tribocatalytic coatings which contain triboactive elements such as Mo and Cu which can interact with lubricants and lead to the formation of friction and wear reducing tribochemical reaction layers. Besides coating development, also the design of lubricants is in the focus of research activities to reach friction reductions. Therefore, increasing interest gains towards low viscosity lubricants e.g. for e-mobility applications, since reduced friction would lead to extended range.Within the current work, triboactive (Cr,Al,Mo)N and (Cr,Al,Cu)N, (Cr,Al,Mo,Cu)N coatings were deposited by means of cathodic arc evaporation (Arc PVD) in an industrial scale coating unit. The contents of Mo and Cu were varied. As substrate material the case hardened gear steel AISI 5115 (16MnCr5E) was used. The effects of Mo and Cu on the phase formation were investigated by means of X-ray diffraction (XRD). Analysis of the mechanical properties was conducted by nanoindentation (NI) measurements. Tribological behavior of the coatings was analyzed under continuous sliding conditions in pin on disc (PoD) tribometer under minimum quantity lubrication with lubricant amounts of V = 0.05 ml at a temperature T = 80 °C. As lubricants, a low viscosity lubrication oil and a conventional mineral oil were used. Both lubricants contained sulphur and phosphor (S-P) or sulphur (S) additives. In order to investigate the influence of the counter part material on the tribological behavior, inert Si3N4 balls and 100Cr6 steel balls were used. Initial Hertzian contact pressures were set to pH ≈ 1400 MPa and pH ≈ 1600 MPa, respectively. Wear was analyzed by confocal laserscanning microscopy (CLSM). Tribochemical interactions between the coatings and lubricants were studied by Raman spectroscopy. It was found that tribochemical interactions between Mo of the coatings and S of the lubricants can lead to the in situ formation of MoS2 in tribological contact.

Modeling the Effect of Moisture on Resilient Modulus of Untreated Reclaimed Asphalt Pavement

The use of reclaimed asphalt pavement (RAP) as a base layer is increasing as quality aggregate becomes scarcer and more expensive. Moisture content is known to have a great impact on the resilient modulus (MR) of granular materials, and several researchers have devoted effort to develop and verify analytical models to describe that impact. Limited work has been done to quantify the effect of moisture content on RAP as a base layer. It has not been determined whether the existence of aged binder will allow designers to use the same analytical models developed for granular materials. This study investigated the effect of moisture content on the MR of a base layer that contained RAP, compared the effect of moisture content on RAP with the effect on typical base material, and reviewed the literature to select a model that would analytically predict changes in the MR of untreated RAP as a result of changes in moisture content.

Laser Beam Build-Up Welding: Precision in Repair, Surface Cladding, and Direct 3D Metal Deposition

Surface coating, repair, and rapid design changes of high-value components and tools are demanding challenges of modern manufacturing technology. In this field, advanced laser-based techniques are of outstanding importance for the related applications in mould and tool, aircraft and aerospace, as well as automotive industry. Many laser cladding solutions have been transferred into industrial series production within the last years. The motivations for the raising interest are given by the typical features of the technology: on the base of closed CAD/CAM chains, a quick and comprehensive treatment even of complex shaped and highly stressed components is possible. The heat input into the workpiece is less compared to TIG or PTA welding, although a metallurgical bonding to the substrate is guaranteed. Furthermore, the precise material deposition even at small partial areas is an advantageous characteristic. The coating materials include metal alloys (Co, Ni, Cu basis, Titanium, and steel), hard metals (e.g., WC/Co, TiC, and VC with metallic binders), and oxide ceramics (Al2O3/TiO2). Typical base materials are steel, cast iron, and lightweight metal alloys based on Aluminum, Titanium, and Magnesium. The accuracy of the produced 3D structures in the range of 0.1 mm is the highest possible in the group of welding techniques. On the other hand, the available system technology (lasers, powder feeders and nozzles, CAD/CAM systems) permits a very easy and successful integration of the laser technology into manufacturing systems. Examples of application are the surface protection of lightweight automotive motor components, repair and quick modifications of metal forming tools as well as the complete restoration of damaged blades and disks of aero engines and gas turbines.

Pavement Joint Sealant Specifications—Past, Present, and Future

Portland cement concrete (PCC) began to be used as a surface or wearing course for pavements in the United States in the early 1900s. The joint sealant or filler materials used during this early construction period were typically sand, tar paper, coal-tar pitch, asphaltic compounds, or wooden blocks. Material specifications for these early joint filler materials were nonexistent. The main emphasis of pavement construction during this period was to "get the country out of the mud" [1], not to provide a long lasting flexible joint sealant material to protect the pavement structure. In the early 1940s, pavement engineers began to concentrate on the construction of the joints in rigid pavements and the materials used to seal those joints. It was during this time period that elastomeric materials (generally an asphalt-based material modified with crumb rubber) began to be developed for use in pavement joints and the first material specifications were developed to provide a means of quality control. As user requirements changed (i.e., materials resistant to fuel spill-age, etc.), new materials (typically polymer modified and/or extended coal-tar materials) were introduced and new material specifications were developed. New formulations have continued to be introduced with individual material specifications eventually being developed for each sealant. Typical base materials used today for pavement joint sealing include asphalt-rubber, modified coal-tar, polysulfide, polyurethane, silicone, and polychloroprene. Improvements have been made to the sealant formulations but the current material specifications have hindered innovation because they are typically material specific and generally do not directly correlate to sealant field performance. A review of the history of joint sealant material specifications, current specifications, and potential techniques that may be included in material specifications of the future to provide a more direct correlation between laboratory evaluation and field performance is presented.