Traffic Paint Research Articles

Identification of solid phase speciation of trace elements in dust dry deposition using focused ion beam and selected area electron diffraction

BackgroundFew studies have been conducted to identify solid phase speciation of trace elements within the interior of airborne particles, although the adverse effects of ambient particles are closely related to the speciation of toxic elements and therefore the identification of chemical binding sites and solid phase associations is essential for assessing the impacts of trace elements in ambient air on environmental quality and human health. ObjectiveA combined use of focused ion beam scanning electron microscopy (FIB-SEM) and selected area electron diffraction (SAED) patterns from transmission electron microscopy (TEM) was applied with an energy dispersive X-ray spectroscopy (EDS) to investigate the solid phase speciation of trace elements within the interior of dust dry deposition obtained from an urban area. ResultsThe study results using the high-resolution microscopic techniques for the characterization of nano- and micron-sized particles revealed lead chromate for Pb and Cr6+, barite for Ba, rutile for Ti, and calcite, gypsum, and quicklime for Ca within the carbon matrix, implying their traffic-related sources. Fe oxides were observed for Fe, Mn, Ni, and Cr3+, with cerianite and Fe-La alloys for rare earth elements (REEs). ConclusionsThree types of anthropogenic sources were inferred based on the morphology and texture of the solid phases, as well as their primary usage: traffic road marking paints for Pb, Cr6+, Ba, and Ti, cement materials for Ca, and industrial activities for Fe, Mn, Ni, Cr3+, and REEs. The presence of submicron-sized toxic metal-bearing particles in dust dry deposition indicated that the toxic metals (i.e., Pb, Cr6+) can penetrate into the respiratory system along with the nanoparticles. The study results demonstrate that the solid phase speciation of trace elements detected using FIB-SEM and TEM-SAED can be effectively utilized for the identification of sources and the assessment of chemical toxicity of atmospheric dust.

The effect of modified titanium dioxide, silica, and zinc oxide on the self-cleaning property of an acrylic resin-based paint

Traffic paints hold paramount importance in road markings and ensuring efficient traffic flow. Self-cleaning marking traffic paints are a type of paint which recently developed to keep traffic lines clean with high visibility. Several paints were formulated with acrylic resin and self-cleaning agents, titanium dioxide (TiO2), silicon dioxide (SiO2), and zinc oxide (ZnO) individually and or in combination. All agents were treated in a furnace at 800°C for 2 hours before incorporating into the paint formulation. The effect of untreated and treated agents on several crucial properties of the formulated paints was assessed and compared. It revealed that heat treatment was effective on the crystallinity and impurity content of the agents evidenced by traditional characteristic techniques. The SEM-EDX analysis confirmed the presence and distribution of self-cleaning agents in the paint matrix. Water contact angles ranged from 68° to 97° for paints with self-cleaning agents, indicating improved hydrophilicity. Oil contact angles ranged from 27° to 42° for most paints with self-cleaning agents, showing some improvement in hydrophobicity. The qualitative assessment confirmed superior self-cleaning performance for paints with self-cleaning agents compared to the reference paint, especially for treated agents. Overall, the type and amount of self-cleaning agents significantly affect the hydrophilicity, hydrophobicity, and self-cleaning performance of paints.

Health Risk Assessment of Heavy Metals in Indoor Household Dust in Urban and Rural Areas of Chiang Mai and Lamphun Provinces, Thailand.

Indoor exposure to heavy metals poses human health risks worldwide, but study reports from Thailand are still limited, particularly in rural and urban areas. We measured the heavy metals in a hundred indoor household dust samples collected from urban and rural areas in Chiang Mai and Lamphun provinces and found a significantly higher concentration of As in rural areas and Cd in urban areas with industrial activities. The source identification of the heavy metals showed significant enrichment from traffic emissions, paint, smoking, and mixed sources with natural soil. From health risk assessment models, children were more vulnerable to noncarcinogenic risks (HI = 1.45), primarily via ingestion (HQ = 1.39). Lifetime cancer risks (LCRs) due to heavy metal exposure were found in adults (LCR = 5.31 × 10-4) and children (LCR = 9.05 × 10-4). The cancer risks from As were higher in rural areas via ingestion, while Cr and Ni were higher in urban areas via inhalation and ingestion, respectively. This study estimated that approximately 5 out of 10,000 adults and 9 out of 10,000 children among the population may develop cancer in their lifetime from exposure to indoor heavy metals in this region.

The effect of acrylic silane crosslinker on room‐temperature cured acrylate binder for road markings

AbstractAn acrylic binder with excellent physical properties is prepared using copolymer of methyl methacrylate (MMA) and butyl acrylate monomer (BAM), 2‐hydroxyethyl methacrylate (2‐HEMA), 3‐(trimethoxysilyl)propyl methacrylate (TMSPMA), and additives. The obtained acrylic resins are subjected to a redox initiator system (ROIS) for room temperature curing. The effects of the TMSPMA concentration and [acryl‐copolymer]/[2‐HEMA] ratio on backbone content are studied in terms of traffic marking paint. The mechanical and morphological properties are thoroughly evaluated using universal testing machine (UTM), UV spectrum, and SEM. With increasing TMSPMA content, the adhesive strength and transmittance of the cured resins increase up to a limiting value of TMSPMA content because of the optimizing crosslink network in backbone structure. The introduction of TMSPMA may be effectively attributed to strong adhesive and high transparency of an acrylic resin series. Consequently, acrylic resins with optimal TMSPMA content can be mostly utilized as a high‐performance binder in the traffic marking paint field.

Silane treatment of drop-on glass-beads and their performance in two-component traffic paints

In this research, the surface of drop-on glass beads (GBs) was first etched, then modified using 3- trimethoxy silyl propyl methacrylate (MS) and trimethoxy vinyl silane (VS) through a sol-gel process to improve GBs’ adhesion to the two-component methyl methacrylate-based traffic paints (known as cold plastic paints). The etching was conducted in acidic, neutral, and basic conditions. Acidic etching condition was selected for the further experiments considering the highest number of OH groups provided by etching reaction on the surface of GBs. The FTIR and 13C-NMR spectroscopy were utilized to characterize chemical composition, and Atomic Force Microscopy (AFM) was used to evaluate the surface roughness / topography of the pretreated and silane-treated GBs. The amount of silane coated on the surface of the GBs was determined using thermogravimetric analysis (TGA). The dispersion of silane compounds on the surface of the treated GBs was assessed using Energy Dispersive X-Ray Analysis (EDXA). Neat and silane-treated GBs were then sprayed on freshly applied cold plastic paint samples using a designed lab spray device. Optical microscopy was used to evaluate the proper embedment depth of the GBs onto the surface of the paint samples. The abrasion test was performed in dry and wet conditions to evaluate the adhesion strength of neat and silane-treated GBs to the paint surface in normal and rainy weather. The coefficient of retroreflected luminance (RL) and the luminance coefficient under diffuse illumination (Qd) were measured to characterize the night and day retroreflective performance of cold plastic paints containing treated and untreated GBs. The abrasion test results showed the least weight loss in the paint markings containing drop-on VS-treated GBs (VS.GBs) in comparison to neat and MS-treated GBs (MS.GBs). This was assigned to increase in adhesion strength and interfacial interactions between VS.GBs and the polymeric matrix. The measured values of RL and Qd also confirmed the excellent maintenance of drop on VS.GBs on the surface of the two-component traffic paints.

Alteration of yellow traffic paint in simulated environmental and biological fluids

Pollution from heavy metals in urban environments is a topic of growing concern because many metals, including Pb and Cr, are a human health hazard. Exposure to Pb and Cr has been linked to the inhibition of neurological development as well as toxic effects on many organs. Yellow traffic paint (YTP) is a mixture that contains organic polymers, binders, and pigments, which in some cases consist of crocoite (PbCrO4) that may be coated by silica. The primary aim of this study was to investigate the behavior of the crocoite pigment grains within YTP and their silica coatings in simulated environmental and human body conditions. To do this, both YTP and asphalt were collected in Philadelphia, PA, USA. These samples as well as a standard PbCrO4 were investigated with powder X-ray diffraction, X-ray fluorescence, environmental scanning electron microscopy (ESEM), transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Using this multi-analytical approach, mineral phases were determined in the YTP, their shape, dimensional distributions, crystallinity, and chemical composition, as well as elemental distributions before and after experimental interactions. Three batch dissolution experiments with YTP, asphalt, and standard PbCrO4 were performed to simulate ingestion, inhalation, and environmental interaction with rainwater. Elemental releases were determined with inductively coupled plasma-optical emission spectrometry, and results indicated that little (ingestion) to no (environmental and inhalation) Pb and Cr were leached from the YTP during the three experimental procedures. This is likely due to the silica coating that encapsulates the crocoite particles, which persisted during all interactions. The ESEM results for YTP showed dimensional reductions after interactions with all three fluids. The silica coating must be further explored to determine how it breaks down in real environmental conditions.

Optimizing practical properties of MMA-based cold plastic road marking paints using mixture experimental design

In this study, some practical properties of methyl methacrylate (MMA)-based cold plastic traffic paints were optimized. For this purpose, in the first step, the effect of initiator, benzoyl peroxide (BPO) content on the polymerization of MMA-based traffic paints was evaluated. No-pick-up time, pendulum hardness, tensile strength and color difference (ΔEw) before and after exposure to the accelerated weathering conditions (AWC) of the samples containing various BPO wt% (0.5, 1.0, 1.5 and 2.0) were determined. In the second step, the MMA-based paint formulation was optimized using mixture experimental design (MED). The amounts of MMA resin, chlorinated paraffin wax (plasticizer) and silica fillers with different average particle sizes were considered as the variables in the paint formulations. Viscosity, reflectance, color difference (ΔEw) before and after exposure to AWC, skid resistance, and dirt pick-up property were selected as the practical properties and responses in the MED. The region of optimum paint formulations was determined using the quadratic model and selecting the desired end-use properties. The accuracy of the model was evaluated, and the results confirmed an appropriate agreement between the proposed model and experimental measurements.The results showed that the BPO initiator in low level of usage did not sufficiently affect the curing rate of the paint samples. In addition, high level of BPO led to decrease in mechanical properties of the paint, due to the presence of plasticizer and non-reacted BPO compounds within the polymeric network. The results also confirmed the MED as an operative method to optimize MMA-based pavement marking paints for purpose of balancing between skid resistance and dirt pick-up properties.

A mineralogical and chemical investigation of road dust in Philadelphia, PA, USA.

Road dust was investigated within Philadelphia, a major United States city with a long history of industrial activities, in order to determine pollution levels. Almost all of the investigated minor elements were enriched relative to the continental crust. Furthermore, mean concentrations of Cr, Co, Cu, and Pb were high compared with those reported in cities in other countries. Lead pollution should be investigated further in Philadelphia, where 8 of the 30 sample sites, including those heavily trafficked by civilians, were at or above the EPA's child safety threshold for Pb in bare soil. High Spearman correlations between Zn and Cu, Zn and Cr, Cu and Cr, and Sn and V, as well as factor analysis of minor elements suggests that the primary sources of these elements were anthropogenic. Potential sources included the breakdown of alloys, non-exhaust traffic emissions, paint, smelting, and industry. We found that higher organic content in road dust may be related to higher traffic densities, which could be due to tire-wear particles. Additionally, higher mean concentrations of Fe, Cr, Cu, and Zn were found at sites with elevated traffic densities. Land use impacted some of the elements not influenced by traffic density, including Co, Sn, and Pb. Bulk mineral content was similar across different land uses and traffic densities and, thus, did not appear to be influenced by these factors. Our research emphasized the complexity of road dust and utilized a more comprehensive approach than many previous studies. This study established fundamental groundwork for future risk assessment in Philadelphia, as it identified several key pollutants in the city. Overall, this assessment serves as an informative reference point for other formerly heavily industrialized cities in the USA and abroad.

Road Dust: A Health Hazard Hidden in Plain Sight

Legacy heavy metals from past industrial activity combine with traffic paint; asphalt; and bits of tires, brakes, and car parts to create toxic dust on our roadways.

Anthropogenic spherules in Zuari estuary, south west coast of India

In this study we report silica rich anthropogenic spherules from the marine environment. We found spherical, dumbbell, teardrop and fused spherules in Zuari estuary (near the Dona paula jetty), south west coast of India. The spherules were composed of SiO2 (69.8%), Na2O (13.2%), CaO (8.8%), MgO (3.8%), and traces of Al2O3, and FeO. Their high Na and Ca contents rules out the possibility of being an impact spherule or microtektite, or anthropogenic spherules coming from fly ash. Their elemental composition suggests that these are glass micro beads that have many applications including production of road and pavement marking materials, such as traffic paints. Considering that the glass micro beads are known to have high concentrations of Pb, As, and Sb that can leach into the marine environment, this study also raises questions regarding the impact of such spherules on marine biota, and highlights the need for further detailed study.

Aluminum Coated Micro Glass Spheres to Increase the Infrared Reflectance

The reflective properties of micro glass spheres (MGS) such as Solid Micro Glass Spheres (SMGS, “glass beads”) and Micro Hollow Glass Spheres (MHGS, “glass bubbles”) are utilized in various applications, for example, as retro-reflector for traffic road stripe paints or facade paints. The reflection behavior of the spheres can be further adapted by coating the surfaces of the spheres, e.g., by titanium dioxide or a metallic coating. Such coated spheres can be employed as, e.g., mid infrared (MIR)-reflective additives in wall paints to increase the thermal comfort in rooms. As a result, the demand of heating energy can be reduced. In this paper, the increase of the MIR-reflectance by applying an aluminum coating on MGS is discussed. Aluminum coatings are normally produced via the well-known Physical Vapor Deposition (PVD) or Chemical Vapor Deposition (CVD). In our work, the Liquid Phase Deposition (LPD) method, as a new, non-vacuum method for aluminum coating on spherical spheres, is investigated as an alternative, scalable, and simple coating process. The LPD-coating is characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and reflection measurements. The results are compared to a reference PVD-coating. It is shown that both sphere types, SMGS and MHGS, can be homogeneously coated with metallic aluminum using the LPD method but the surface morphology plays an important role concerning the reflection properties. With the SMGS, a smooth surface morphology and a reflectance increase to a value of 30% can be obtained. Due to a structured surface morphology, a reflection of only 5% could be achieved with the MHGS. However, post-treatments showed that a further increase is possible.

Synthesis of acrylic resins for high-solids traffic marking paint by solution polymerization

ABSTRACTFast-drying traffic marking paint comprising a solvent-borne resin, a filler, a pigment and a solvent that is especially suitable for colder ambient (temperatures near freezing) applications, where waterborne traffic paint cannot be used. Acrylic resins based on methyl methacrylate, butyl acrylate, acrylic acid, and styrene were synthesized in different solvents using organic peroxide initiators such as peroxyester, peroxyketal, dialkylperoxide and azo. After polymerization, the molecular weight (Mw), polydispersity index = PDI (Mw/Mn), viscosity, total residual monomer and APHA color were evaluated and results of organic peroxide initiators (t-butyl and t-amyl derivatives) were compared with the azo initiator. The Mw, PDI, viscosity, mass conversation and APHA color of resins with t-amyl derivatives of organic peroxide initiators are very proper.

The role of soil mineralogy on oral bioaccessibility of lead: Implications for land use and risk assessment

Understanding the oral bioaccessibility of lead (Pb) present in soils in urbanized areas is important for the human exposure risk assessment. In particular, the role of the soil-mineralogy in the oral bioaccessibility has not been extensively studied. To investigate bioaccessibility, five types of periurban soils were collected, samples were spiked with the same amount of lead-chromates from traffic paint, and subjected to the in vitro Physiological Based Extraction Test (PBET). Ten samples of urban topsoils were collected at elementary schools playgrounds, Pb-bioaccessibility was measured, and a prediction equation for bioaccessibility was constructed. Mineralogy, and metal content were identified with a combination of X-ray powder diffraction, scanning electron microscopy, and portable X-ray fluorescence techniques. Traffic paint sample is made of 15% quartz (SiO2), 13% crocoite (PbCrO4), 55% calcite (CaCO3), and 17% kaolinite (Al2Si2O5(OH)4) and it contains high metal content (Pb, Cr, Zn, and Ca). Studied soils are characterized by variable amounts of acid-neutralizing minerals (carbonates) and low metal content. Spiked soils contained almost equal concentration of Pb, Cr, and Zn, because the contribution of these metals is from the added paint. However, obtained Pb-bioaccessibility at gastric and intestinal conditions are variable (40 to 51% gastric, 24 to 70.5% intestinal). Carbonate content shows significant correlation (p < 0.05) with Cr, Ca, calcite, crocoite, and Pb-bioaccessible at gastric conditions. Correlation of Pb-bioaccessible at intestinal conditions is significant (p < 0.05) with kaolinite.Variability of Pb-bioaccesibility in urban environments is commonly associated to differences in Pb-sources, however, our results show that the bioaccessibility of the same pollutant behaves different for each soil type. This suggests that soil mineralogy may play a role in Pb-releasing at gastrointestinal conditions. Soil information about mineralogical characteristics from this study may help to reduce exposure to lead from urban sources if data are incorporated into urban planning.

Characterization of Cr (VI) – Containing solid phase particles in dry dust deposition in Daejeon, South Korea

Solid phase speciation of chromium in dry dust deposition and road paint was determined using transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAS). Spherical black carbon aggregates in dry dust deposition contained discrete nano-sized lead chromate (PbCrO4) and zinc chromate (ZnCrO4), which likely originated from yellow traffic paint and zinc chromate primer (corrosion resistant pigment), respectively based on their main applications. Road marking paint samples from auto roads included lead chromate particles whose size, shape, composition and crystal structure were similar to those in dry dust deposition. A slight difference was found at the particle boundary. Namely, lead chromate in traffic paint was encapsulated by silica-bearing matrix, while discrete lead chromate in the black carbon of dry deposition was rarely enclosed within silica-bearing matrix. The Cr K edge X-ray absorption near edge structure (XANES) spectrum for dry deposition showed the characteristic pre-edge resonance peak similar to the spectra for the Cr(VI) standard and road paint, but the lower intensity. The amount of Cr(VI) accounted for approximately 45% of the total Cr in the dust sample. The solid phase speciation of Cr observed using TEM and their valence states determined using XANES were consistent with the chemical speciation determined using the sequential extraction. The contribution of this study is that XANES was applied to identify Cr valance states in urban dust deposition and zinc chromate was found as a Cr(VI) phase in dry dust deposition using TEM. These study results provide novel data on Cr speciation and Cr(VI)-containing mineral phases in dry dust deposition and their potential sources. Based on the wide use of lead and zinc chromate, atmospheric contamination with these solid phase speciation of Cr(VI) is expected in other cities in the world.

Emissions of Volatile Organic Compounds from road marking paints

Regulations, definitions, and calculations related to emissions of Volatile Organic Compounds (VOC) from paints used for horizontal road markings (traffic paints) in North America and in European Union are different, which frequently makes simple comparisons impossible. To illustrate the dissimilarities, solvent packages of various exemplary paints that meet several normative requirements were compared for the nominal emissions according to different calculation procedures. For a unified assessment, volatile portions of the paints were evaluated based on Ozone Formation Potential (OFP). The analysis revealed that similar nominal VOC contents can lead to vastly different OFP, in an extreme case six times higher. Incongruously high OFP, which was calculated for emissions in Southern California despite strict limits can thus be explained. The provided calculations can be used by road administrators as a tool to demand materials with lowest environmental impact, by environmental researchers to pinpoint irregularities between declared and measured discharges, and can assist formulating chemists in selection of raw materials to prepare environmentally friendly road marking paints.

Wear Properties of Nanocomposite Traffic Marking Paint

Durability and wear properties of traffic marking paints are one of the most important challenges in traffic management. This provides high-value cost-benefit, crowd reducing, improving journey times and decreasing environmental targets which are made by standing or slow-moving traffic. Because of the volume of traffic passing, climatic conditions, type of road surface, and drivers’ behavior, a traffic marking paint gradually loses its basic properties such as durability and night visibility (RL) that may potentially lead to accidents because of a loss of cognitive perception for drivers. Therefore, an effective wear resistance traffic marking paint is desirable to reduce wear, extending the lifetime and durability of paints. Analyzing this effect via microgranules, nanoclay application is the aim of this study. Clay/acrylic resin nanocomposite is synthesized using Cloisite® 30B with different percentages. Finally, production of traffic marking paint nanocomposites with this nanocomposite acrylic resins can offer the promising prospect for these aims.

Source apportionment and environmental fate of lead chromates in atmospheric dust in arid environments

The environmental fate of lead derived from traffic paint has been poorly studied in developing countries, mainly in arid zones. For this purpose, a developing city located in the Sonoran desert (Hermosillo, Mexico), was chosen to conduct a study. In this paper the lead chromate (crocoite) sources in atmospheric dust were addressed using a combination of Raman microspectroscopy, X-ray diffraction, scanning electron microscopy (SEM), and Pb isotope measurements. A high concentration of Pb and Cr as micro- and nanostructured pigments of crocoite is reported in yellow traffic paint (n=80), road dust (n=146), settled dust in roofs (n=21), and atmospheric dust (n=20) from a developing city located in the Sonoran Desert. 10 samples of peri-urban soils were collected for local geochemical background. The paint photodegradation and erosion of the asphaltic cover are enhanced by the climate, and the presence of the mineral crocoite (PbCrO4) in road dust with an aerodynamic diameter ranging from 100nm to 2μm suggests its integration into the atmosphere by wind resuspension processes. A positive PbCr correlation (R2=0.977) was found for all studied samples, suggesting a common source. The Pb-isotope data show signatures in atmospheric dust as a product of the mixing of two end members: i) local soils and ii) crocoite crystals as pigments in paint. The presence of lead chromates in atmospheric dust has not been previously documented in Latin America, and it represents an unknown health risk to the exposed population because the identified size of crystals can reach the deepest part of lungs.

Factors affecting Dirt Pick up of Traffic Paints in Areas with Different Characteristics: Tehran Roads as a Case Study

Factors affecting Dirt Pick up of Traffic Paints in Areas with Different Characteristics: Tehran Roads as a Case Study

Self-cleaning traffic marking paint

A traffic marking paint, because of its function undergoes local climatic conditions such as variations in temperature, the structure of asphalt, vehicles, drivers’ behavior, exposure to ultraviolet radiation (UV) and to pollutants (rain, organic and inorganic particles, mineral dust etc.), gradually loses its fundamental properties such as day visibility (Qd), night visibility (RL) and colorimetry thus resulting in a loss of cognitive perception for the driver that is dangerous that may potentially lead to accidents. Therefore, an effective self-cleaning coating is desirable. In recent years, “Self-cleaning” paint using photocatalytic titanium dioxide (TiO2) has gained considerable industry attention. With the assistance of little UV light from fluorescence source or sunlight, TiO2 offers two unique properties: (a) strong oxidation power, and (b) super-hydrophilicity. Strong oxidation power can be used to clean dirt attached on the paint. Super-hydrophilic property can allow dirt to be easily washed away with water or rainfall. The aim of this investigation is to analyze this effect via study of the decomposition – under UVA irradiation. Finally, TiO2 nanoparticles can offer the promising prospect for this application.

Modernizing and Streamlining Waterborne Traffic Paint Specifications

Quick-dry waterborne traffic paints have dramatically improved since their introduction more than 25 years ago, largely because of improvements in waterborne polymer technology. Paints today can be designed to better meet the needs of the pavement marking industry, but the improved performance is only realized when specifications are kept up to date. Because of the many separate specifying agencies, there is significant disparity in specifications in terms of approach, requirements, test types and procedures, and language. Furthermore, specifications are commonly filled with historical remnants (i.e., tests that are outdated or redundant or that do not predict or correlate with performance in the field). This paper draws on three decades of laboratory and field trial data to demonstrate some of the variation in performance from one paint to another and to provide some guidance on what types of tests and specifications can help a road authority ensure it is getting good quality traffic paint. The data are presented to outline and propose strategies for updating, improving, and streamlining waterborne traffic paint specifications.