Surfacing Materials Research Articles

An experimental study on the tensile properties of reinforced asphalt pavement

Abstract Utilizing one of the most effective new technologies is the primary goal of this research, which uses a combination of bituminous surfacing materials with geotextile reinforcement sheets, to improve the behavior of asphalt mixes and fatigue reduction. The aim of this research is to analyze the impact of woven geotextile upon fatigue characteristics of hot mix asphalt mixtures. In order to improve the tensile qualities of the asphalt pavement, the experimental program for this study includes the application of geotextile within the wearing layer. Marshall fatigue and stability tests were carried out. Four-point bending test in a strain-controlled mode was adopted in this study. Three micro strain levels (250, 400, 750) at a frequency of 5 Hz were used. The findings demonstrated that unreinforced mixtures have a shorter fatigue life than wearing layers reinforced with geotextile. Additionally, exposure to different temperatures (5, 20, 30°C) showed that the performance of the geotextile interlayer system in cold environments is inferior to that of those in warm and moderate climates. The analyzed geotextile has a positive impact on the performance of the pavement and a large potential to extend the life of the pavement as a whole, according to the obtained results of fatigue life.

WEAR-RESISTANT POWDER MATERIALS FOR PLASMA-POWDER SURFACING

Among powder surfacing materials with high hardness and resistance to abrasive wear, powders based on WC-TiC-Co systems, which are the basis of hard alloys, are among the most promising. (Research purpose) The research purpose is investigating wear-resistant powder materials for plasma-powder surfacing by electrodispersing solid alloy waste of the T30K4 brand in kerosene. (Materials and methods) We chose substandard carbide plates of the T30K4 brand as the starting material; lighting kerosene as the working fluid. We solved the tasks set in the work on the study of the composition, structure and properties of the obtained carbide powders using modern equipment and complementary methods of physical materials science. Electrodispersion of solid alloy waste was carried out on the original installation; the shape and morphology of the particle surface were studied on an electron-ion scanning microscope with field emission of electrons QUANTA 600 FEG; particle size composition ‒ on a laser particle size analyzer Analysette 22 NanoTec; X-ray spectral microanalysis of particles was carried out on an energy dispersive X-ray analyzer of EDAX company, integrated into a scanning electron microscope QUANTA 200 3D; phase analysis of particles was performed on an X-ray diffractometer Rigaku Ultima IV. (Results and discussion) A new technology for producing a carbide electroerosive powder suitable for plasma-powder surfacing has been developed and investigated, the effectiveness of which is confirmed by the properties of the proposed powder material: the spherical shape of powder particles; the average size of powder particles is 58.4 micrometers; powder particles with a uniform distribution of alloying elements: C, Co, Ti and W; powder particles include phases of carbides WC and TiC. (Conclusions) The conducted studies have shown that it is possible to obtain a wear-resistant powder alloy with a uniform distribution of alloying elements by the method of electroerosive dispersion of solid alloy waste of the T30K4 brand.

Hardening technology of metallurgical equipment parts by high-speed nitrogen alloys

The technology for hardening of metallurgical equipment parts by high-speed alloys with high nitrogen content is developed. The manufacturing process of deposited parts includes: machining of the workpiece, plasma surfacing, high-temperature tempering, finishing machining and quality control. To form a coating on 30KhGSA steel, an installation for plasma surfacing of bodies of rotation is used. A method and surfacing materials for multilayer plasma surfacing are developed, which make it possible to obtain deposited layers made of high-speed alloys (type R18Yu), additionally alloyed with nitride ferrochrome and titanium, which allows increasing the nitrogen content from 0.02 to 0.12 %. The surfacing method with low-temperature heating and surfacing materials prevent the formation of cracks during the surfacing process and ensure the hardness of the deposited metal up to 59...60 HRC without additional heat treatment. The hardness of the deposited metal after high-temperature tempering at a temperature of 560...580 °C increases to 62...64 HRC. Multilayer plasma surfacing made it possible to obtain a high-quality surfaced layer without cracks, pores and microstructure defects. The main phases of the deposited layer are a solid solution of α-iron, carbides and carbonitrides based on iron, tungsten, molybdenum, chromium, aluminum and titanium. The wear resistance of the deposited parts of metallurgical equipment (rolls and rollers of crushers) increases by 1.5—2.0 times.

Light-coloured concrete surfacing for urban heat-island mitigation in Southern Africa

Global population growth and rapid urbanisation have resulted in the rapid transformation of natural topographies that are now dominated by engineering materials and structures. It is widely recognised that economic development is largely attributable to infrastructure development. However, this development has come about with adverse consequences. In this paper, the effects of surface characteristics, climatic parameters and material properties on the thermal environment and near-surface heat islands in urban areas were investigated. An experiment was conducted in which simple concrete structures with varying surface characteristics were constructed and instrumented. The effect of solar absorptivity was clearly visible, with structures surfaced with low absorptivity materials exhibiting lower surface and effective temperatures. Following the experimental programme, numerical simulations of the simple concrete structures were performed using finite element modelling. The analyses showed that the thermal environment of concrete structures is sensitive to changes in solar absorptivity, climatic parameters, cross-sectional dimensions, and material properties. It was found that the use of low absorptivity or highly reflective surfacing and the selection of appropriate dimensions can be used to significantly reduce the temperatures of concrete infrastructure, including buildings and pavements, thereby providing an evidential basis for the use of low absorptivity surfacing materials to mitigate climate change in Southern Africa.

Efficiency of Different Anti-Dust Agents in Reducing Dust Emission from Forest Road and Deposition on Leaf Surface

Dust is often generated from the dry surfaces of unpaved forest roads as a result of vehicular traffic. Dust particles can negatively affect vegetative growth, water quality and road traffic quality. In this study, some environmental friendly anti-dust agents including sugar cane molasses, polyacrylamide (PAM) and bentonite were used to control dust emission from the road surface under three different concentrations within the 3, 9, 27 and 81 day timeframe. Rear-mounted spray system and dustometer devices were used for implementation of treatments and dust emission recording, respectively. Leaf samples were collected from trees adjacent to road to measure the dust deposited on the leaves by centrifuging dust solution. The results showed that molasses achieved higher efficiencies in term of dust reduction and cost effectiveness than those of PAM and bentonite in Loveh forest, where high levels of fines are present in the road surface materials. 2% and 4% PAM were the most efficient dosages in terms of dust control and cost effectiveness in Shastkalateh and Kouhmian forests, respectively. It was detected that in all sites most of the dust emitted from the road surface was deposited on the leaves of Carpinus betulus L. and Alnus subcordata L., while smooth surface of the leaves retained lower amount of dust in Parrotia persica CAM. It is concluded that the amount of fine aggregates in surfacing materials, type and dosage of anti-dust agent play an important role in the effectiveness and longevity of treatment.

Purifying Effect Evaluation of Pavement Surfacing Materials Modified by Novel Modifying Agent

Functional pavement material with exhaust-purifying performance has been focused gradually in recent years. For improving the purifying effect of functional micro surfacing, two types of raw ore powders with exhaust-purifying potentials were selected as novel functional modifiers. Firstly, the road performance of purifying micro surfacing was evaluated according to the ASTM and ISSA standards. Then, the dispersion state of modifying agent in emulsified asphalt evaporation residue was analyzed and discussed through using SEM and FTIR. Finally, the purifying effect of micro surfacing on exhaust was examined in laboratory to investigate the impact of various experimental conditions on purifying performance. Meanwhile, the purifying performance was also monitored in field test. The results showed that road performance of purifying micro surfacing could fulfill the requirements of relevant technical standards. Pyrite had better dispersion property than specularite and titanium dioxide inside asphalt. The purifying micro surfacing could achieve better purifying effect on NOx and COx than traditional micro surfacing with TiO2. These environmental-friendly pavement materials would provide new solutions for the reduction in polluting emissions of automobile exhausts.

Effects of molasses, polyacrylamide and bentonite on dust control in forest roads

In this study, some environmentally friendly anti-dust agents including sugar cane molasses, polyacrylamide and bentonite were used to control dust emission from the forest road surface within the 3, 9, 27 and 81-day timeframe. A rear-mounted spray system and dust collector devices were used for implementation of treatments and dust emission recording, respectively. The results showed that emitted dust tended to decrease with the increase of anti-dust agent concentrations. Moreover, the emitted dust started to decrease with time, with minimum reduction efficiency at the end of the 81st day. More than half of road surface aggregates had the size smaller than 10 µm that were aggregated by the application of molasses and polyacrylamide. The size of 70% of the road surface fines increased to more than <br />50 µm. Bentonite affected negatively road surface materials and caused fine aggregates to increase. It is concluded that the amount of fine aggregates in surfacing materials, rainfall occurrence, and type and dosage of anti-dust agents play an important role in the effectiveness and longevity of treatment

Rebuilding the wheelset flanges of locomotives by surfacing without wheeling out

The most effective method to increase the surface life of wheel tires, the flange wear of which outpaces the growth of tire wear significantly, is surfacing of worn flanges of electric locomotive wheel sets. This method, in comparison with the restoration by turning and forming a profile configuration by reducing the thickness of the tire has undeniable advantages: flange surfacing combined with the shape of female profile minimizes the technological wear of the tire before its retirement; idle time of locomotives caused by the need of intermediate turning is eliminated; the costs of maintaining the machines for turning without removing the wheels and purchasing hard-alloyed cutting tools are decreased; wage savings are achieved. The work presents basic information on wheel sets, theoretical data on surfacing, analyzes previously used surfacing materials and provides metallographic studies of the surfaced material. The technology of flange surfacing without removing the wheels from under the electric locomotive was developed and described, that allows reducing the time spent on repair significantly. The use of alloyed surfacing materials instead of low-carbon ones allows reducing the time of surfacing and increasing the resistance to wear of wheel set flanges of traction vehicles. Efficiency of NP-18H1G1M.01 surfacing wire application for wear-resistant surfacing of tire flanges and increase of the overhaul cycle is shown. Increased wear resistance of electric locomotive wheel flanges surfaced with alloyed wire is confirmed by the production test data.

Thermal insulation performance of GFRP squared tube reinforced sandwich panel

Recently, the structural insulated panels (SIPs) with the wood-based surfacing materials are developed in housing industry to increase the thermal efficiency of the wall system. In order to integrate the waterproof feature into SIPs, a newly designed GFRP reinforced squared tube sandwich panel (GSTPs) is introduced, where the Glass fibre reinforced polymers (GFRP) is utilized as surface material and the core is reinforced by the GFRP square tube. This paper focused on the thermal insulation performance of GSTPs. Both experimental, theoretical and numerical methods are employed to study their thermal insulation performance as roof panels. More specifically, the thermal conductivity of GFPR with three different core materials, including glass wool, Extruded polystyrene (XPS) and Polyurethane (PU) in the SIP, was first measured by hot plate apparatus (HPA) in the steady-state heat transfer tests. Then, the heat transfer coefficients of three type of GSTPs with above mentioned core materials are measured by guarding heat box (GHB) test. The theoretical and finite element (FE) method based numerical studies applied to conduct the heat transfer analyses on those SIPs. The accuracies of the theoretical and numerical studies are verified by comparing the obtained heat transfer coefficients with those from the experimental tests. The results from the present study could provide a good reference to the selection of the suitable panel thickness and core materials for different thermal regions in China.

Restoration by electric arc surfacing of rollers made of 24CrMo1V installed on secondary cooling system by continuous casting plant

The study is devoted to the selection of surfacing materials for manufacturing and (or) reconstruction electric arc surfacing of rollers of the secondary cooling system of steel continuous casting plant made of 24CrMo1V steel in order to increase their service life.

Increasing the durability of working elements of equipment for abrasive-containing masses processing

The operating parameters of modern equipment for transportation, mixing and pressing of an abrasive-containing masses are examined. The main wear modes are determined to which the working surfaces of the specified equipment are exposed during its operation. The list of main materials of which the working elements of the considered equipment are made, as well as the list of the main serial surfacing materials used for their hardening are shown. The mechanism of abrasive wear of coatings based on W2C – WC and coatings based on TiB2 – TiC was investigated

Shade provision in public playgrounds for thermal safety and sun protection: A case study across 100 play spaces in the United States

Outdoor recreational spaces for children are a highly valued aspect of society to support child well-being. However, there are many important health considerations, such as surface temperatures and ultraviolet radiation exposure that are neglected in traditional initiatives of playground safety, which may impact children’s exposures during play.The present study provides an overview of a safety assessment of playgrounds in the United States, specifically investigating 103 public playgrounds for an applied understanding of the relationship of surface-to-air temperatures for installed surfacing materials, and the prevalence of shade during peak midday hours.Results demonstrate that natural surface materials resulted in moderated temperatures relative to ambient temperature, while artificial surfaces resulted in higher surface temperatures than ambient. Minimal shading was encountered, 67% of playgrounds visited were not shaded between the hours of 10:00 a.m. and 2:00 p.m.This case study provides critical insight, discussion, and novel questions pertaining to the holistic consideration of numerous aspects of playground safety, which can mutually support social and ecological values while providing health co-benefits. Not only are important health risks, such as sunburns and temperature extremes ignored in current playground safety guidelines, but much of the essential information is not available to the end-users making design decisions that may affect the safety and active play experience for the users. Our results strongly motivate future large-scale studies assessing the influence of design on ambient exposures and the provision that bioclimatic principles and greenspace have a central role in playground design.

Safety of School Playgrounds: Field Analysis From a Randomized Sample.

Research supports recess, however, playground injuries are prevalent with more than 200,000 cases per year requiring medical attention. School playgrounds are among the leading location for injury. The purpose was to identify the safety and risk factors of playground environments and impact attenuation characteristics of surfacing materials. Results demonstrated 46% playground spaces protected students from traffic. Results found 75% of playgrounds were exposed to full sun, and unitary surface materials were up to 49°F warmer than the air temperature. There was an increase in the probability of risk whether equipment height was over 9 ft for loose fill surfacing materials or over 6 ft for unitary surfaces. Loose strings or ropes looped over equipment were found on 23% of playgrounds. This study provides discussion and data pertaining to numerous aspects of playground safety. Strategies for school nurses are shared to shape policies and education for playground safety practices.

Evaluation of Some Parameters of Hard Surfacing Treatment of the Functional Surfaces of Forestry Tools

Abstract In this paper we discuss the possibility of increasing service life of tools used in forestry for mulching of undesirable forest growths. In a heterogeneous working environment in which they are operated, such tools are subjected to constant abrasion and impact loading. There are several ways how to extend their service life and operational fitness. One of these is hard surface treatment, or hard surfacing of their functional surfaces. In our experiment, we chose suitable hard surfacing materials and applied these on the sample materials using the MMA and MAG welding. The hard surface was applied in an one layer. Subsequently, we performed hardness tests, microscopic analysis of the structure of the basic material and the hard surface and evaluation of the fusion penetration of the base material with the hard surfacing weld. Fusion is crucial as it determines the cohesiveness of the weld and base materials and thus also the actual extension of the service life of the tools.

Technological Improvement of Surfacing of Parts of Hammer Crushers Used in Coke-Chemical Industry

A technology of manufacturing surfacing with high-chromium special cast iron without heating is developed; the main directions for improving surfacing quality are outlined. It is proposed to replace manual arc welding with plasma surfacing using high-speed hard surfacing materials.

Sandboxes, loose parts, and playground equipment: a descriptive exploration of outdoor play environments

ABSTRACTThe purpose of the study was to examine outdoor environments to understand whether or not young children had access to play materials and loose parts to enhance their playful experiences. This study sought to gather the availability of SAFE and quality play opportunities in early childhood outdoor environments. The study took place in one state of the United States. The study found 75% of outdoor spaces had a playground structure that including a place for children to climb and slide down. The study found 83% of programs had appropriate surfacing materials provided in the outdoor play environment. Loose parts, such as toys, balls, and action figures were also included in the outdoor play and learning environment. The significance of play that this study shows is outdoor environments have an abundant opportunities to support the developmental characteristics of children.

Effects of accelerating and decelerating tramway loads on bituminous pavement

The concept of a tramway on tires will allow authorities to provide a modern and efficient transportation system that is well suited to medium-sized towns and suburbs of larger urban areas. Precision in terms of levelling and evenness plays a very important role in the proper functioning of vehicles and in user comfort. These requirements can be satisfied through adequate mechanical resistance against rutting, cracking, and fatigue, and through adequate behaviour of the materials within the structure. These facts motivated the authors to conduct a material and structure study pertaining to the effects of speed and the horizontal forces acting on viscoelastic surface layers that could possibly affect the pavement design. In order to study the various effects of moving loads (braking, accelerating and cornering) on bituminous pavement, numerical calculations were carried out with the help of the ViscoRoute Software version 1.0. The study revealed that the surface layer is subjected to the highest degree of longitudinal shear stress at the driving axles when the tramway is braking or accelerating. These effects decrease with the depth of the pavement materials. The first and second stress invariants (mean stress and deviator stress) are used to show the stress path under the accelerating and braking tramway. When the temperature increases, the same description can be applied to the various load conditions. The stress invariants provide valuable insight into the three-dimensional response of the material, and may be useful in terms of introducing a yield surface for modelling permanent deformations and a more realistic experimental protocol for evaluating the behaviour of bituminous surfacing materials in the laboratory.

The summer thermal behaviour of “skin” materials for vertical surfaces in Athens, Greece as a decisive parameter for their selection

This paper analyses the thermal behaviour of the materials, which are widely used on the vertical surfaces of Greek cities. This analysis is based on surface temperatures measurements, which were carried out both in situ in various buildings of Athens, Greece and experimentally on samples of building materials exposed to solar radiation on a building’s flat roof. The study includes surfacing materials, which are usually applied on building facades around Greece. The study leads to a number of conclusions concerning the effect of colour and orientation on the summer surface temperatures of materials, used on vertical city surfaces. These conclusions indicate how surfacing materials should be chosen in order to help mitigate the urban heat island and improve thermal comfort conditions in the outdoor spaces of Greek cities during the overheated summer period.

Recycling surfacing materials back into thin surfacing systems

The need to recycle thin surfacing systems is more critical than for many other generic surfacing materials because they contain a high quantity of relatively scarce aggregates with high skid-resistance properties. Laboratory investigations and site trials have been successfully undertaken to assess the feasibility of incorporating reclaimed surfacing materials in these systems. The trials were on an access road to an asphalt plant and on two heavily trafficked sites on the UK road network and included the use of polymer-modified binders and up to 30% reclaimed asphalt in the mixed asphalt. The trials demonstrate that 10% reclaimed asphalt can be easily added to new materials without processing the reclaimed asphalt. As the proportion of reclaimed asphalt increases up to 30%, greater care needs to be taken on assessing grading compatibility and how to treat the residual binder present in the reclaimed asphalt as a proportion of the ‘active’ binder content in the recycled surface course layer. The use of reclaimed asphalt in the surfacing has also been monitored on a major motorway contract.

Chloride Stabilization of Unpaved Road Aggregate Surfacing

There are few alternatives for improving long-term performance of aggregate surfacing materials in dry climates other than annual dust abatement treatments. In-place stabilization of properly graded aggregate with chloride additives is cost-effective and provides performance and intangible benefits. Similar results are achieved by mixing additives with aggregate during crushing. This 2-year study identifies conditions in which chloride-stabilized roads have a projected life of 10 years or more if properly maintained. The greatest benefits are realized in projects with high aggregate surfacing replacement costs and average daily traffic volumes that exceed 100. Stabilization provides a higher standard of road surface performance by improving ride quality and reducing dust, corrugations (washboarding), and raveling (loose aggregate). Other intangible benefits include reduced sedimentation in streams, reduced aggregate resource depletion, reduced health hazards from dust, and increased road-user safety. This project developed guidelines for chloride stabilization of various aggregate surfacing materials in semiarid to arid environments. Performance and cost-effectiveness of chloride stabilization were measured on 12 projects and monitored for two seasons in four western states; monitoring included construction and maintenance costs, road surface deterioration, traffic, weather conditions, environmental effects, and materials testing. Treated surfaces needed blading after 25,500 vehicles, whereas untreated surfaces needed blading after only 3,200 vehicles. Environmental effects on trees, streams, and roadside soils were insignificant. Many tools were developed to assist in the proper implementation of chloride stabilization of road surface aggregates.