Asphalt Fumes Research Articles

Mechanical properties of Cold Recycled Bituminous Mixes with Crumb Rubber

Cold mix recycling technologies based on asphalt emulsion have been acknowledged for allowing to reduce the environmental burdens associated with road pavement maintenance and rehabilitation. In fact, mixing and placement are conducted at lower temperatures leading to energy savings, a reduction of asphalt aging, fume and odour releasing, and a general decrease of airborne emissions. However, there are still several concerns related to the high variability of reclaimed asphalt pavement (RAP), the lack of standard mix-design procedures and the fair/low mechanical performance often achieved especially due to poor moisture resistance. On other side, the addition of crumb rubber into hot mix asphalts is considered an environmentally-friendly and cost-effective practice in several countries. Producing bituminous cold mixes containing crumb rubber to develop a “greener” paving material with a performance level comparable to that of conventional materials, represents a great challenge to materials engineering. This paper presents the results of a laboratory investigation concerning the mixdesign characteristics of cold 100%-recycled asphalt emulsion mixes, using crumb rubber to improve cold recycling engineered properties. Mechanical and volumetric properties were assessed through dynamic modulus and indirect tensile strength on dry and water-conditioned specimens.

Percutaneous Absorption of Polycyclic Aromatic Compounds from Fume Condensates of Paving and Built Up Roofing Asphalts

Paving and roofing workers can be exposed to low levels of polycyclic aromatic compounds (PACs) while working with asphalt at elevated temperatures via both the inhalation and dermal routes. Inhalation exposure date are readily available. However, dermal information is more complicated and not as well-studied. Here we evaluate condensed fumes from four paving and four BURA asphalts for percutaneous absorption through human skin using in vitro studies. Test materials included eight asphalt (bitumen) fume condensates (AFCs) collected from the headspace above four paving and four Type III built up roofing asphalt (BURA) tanks, each proven to match worker breathing zone exposures. Sections of human cadaver skin were sliced with a dermatome to a thickness of 250–350 μm, one-inch circular pieces were mounted in Franz diffusion cells epidermis side up. Receptor fluids were sampled at intervals over 48 hr and the aliquots analyzed for PACs using HPLC with fluorescence detection to determine the dermal flux rates of anthracene, fluoranthene/pyrene, and total 3-6 ring PACs.For paving/BURA AFCs, respectively, the average (N = 4) concentrations (μg/g) were: anthracene, 50.6 (SD = 14)/27.2 (SD = 28); fluoranthene/pyrene, 66.5 (SD = 47)/83.2 (SD = 100); Ʃ3-6 ring PACs, 833 (SD = 302)/2191 (SD = 240). Dermal flux rates (ng/cm2/hr) were: anthracene, 4.4 (SD = 1.1)/1.9 (SD = 2.0); fluoranthene/pyrene, 3.8 (SD = 2.8)/3.6 (SD = 5.0); Ʃ3-6 ring PAC, 35 (SD = 14)/21 (SD = 15). The estimated dermal flux of benzo[a]pyrene B[a]P in paving AFCs ranged from 0.0006 to 0.007 ng/cm2/hr and for BURA AFCs from 0.016 to 0.19 ng/cm2/hr. The averaged experimentally determined permeability coefficient (Kp) for anthracene for all eight samples was 0.90 ± 0.13 × 10−4 cm/hr (95% CI). Results show limited absorption of PACs across the skin in AFCs under the most conservative conditions (occluded/infinite dose). Dermal flux results can be used to support dermal exposure and risk assessments for asphalt emissions.

Emissões do asfalto e seus efeitos na saúde humana

Este trabalho tem por objetivo levantar os principais riscos para alunos, professores, técnicos de laboratório e demais trabalhadores do setor de pavimentação quando expostos às emissões de fumos e vapores do asfalto aquecido. Para tanto, foi feito um levantamento na literatura especializada e determinou-se através de pesquisas de diversos autores da área, os principais compostos dos fumos e vapores de asfalto que são lançados na atmosfera e, as possíveis doenças que são decorrentes da exposição humana a tais compostos. Os fumos e vapores de asfalto possuem em sua constituição química, hidrocarbonetos policíclicos aromáticos (HPAs), os quais podem ser cancerígenos. Para se verificar a possibilidade de carcinogenicidade dos HPAs foi feito um apanhado das principais publicações na área de saúde ocupacional que tratam das emissões do asfalto. Foi realizado um levantamento sobre o histórico da evolução das pesquisas sobre o assunto.Dentre os vinte principais autores pesquisados acerca da carcinogenicidade dos fumos e vapores do asfalto, onze afirmam que as emissões do asfalto são cancerígenas para o ser humano quando há exposição em longo prazo, cinco autores afirmam que há grandes possibilidades do desenvolvimento de câncer e quatro autores afirmam não haver dano para a saúde humana. Não havendo plena certeza dos potenciais riscos oferecidos à saúde humana pelas emissões do asfalto, deve haver cautela com a exposição de trabalhadores e pesquisadores a tais componentes.

Avaliação da exposição e risco de câncer em trabalhadores da pavimentação: um estudo baseado nos níveis de partículas respiráveis presentes nos fumos de asfalto

Serviços na área de pavimentação asfáltica são comumente empregados nos grandes centros urbanos. Recentemente, a International Agency for Research on Cancer (IARC) classificou as partículas atmosféricas externas como pertencentes ao Grupo 1, isto é, comprovadamente carcinogênicas a humanos. Desta forma, o principal objetivo deste estudo foi avaliar os níveis de Material Particulado Respirável (MPR) presentes nos fu-mos de asfalto, bem como o risco a saúde dos trabalhadores desse setor durante o processo de pavimentação, tanto na usinagem quanto na aplicação do material asfál-tico em campo. Os resultados do estudo mostraram que na usina foram encontrados os maiores níveis de MPR, sendo os mesmos influenciados, principalmente, pela ele-vada produção de material. O MPR obtido durante a aplicação em campo apresentou concentrações menores e foi influenciado pela quantidade de material asfáltico utili-zado na obra, a temperatura da mistura asfáltica durante a aplicação e a ventilação no local de aplicação. A exposição diária e o risco de câncer foram considerados maiores na usina se comparados aos valores encontrados em campo. Em ambos os locais, esses níveis ultrapassam os limites estabelecidos pelas principais agências que regulam a sa-úde ocupacional. O tipo de via urbana influenciou na distribuição dos níveis de MPR e, consequentemente, na exposição e no risco de câncer aos trabalhadores do setor.

The engineering, economic, and environmental performance of terminal blend rubberized asphalt binders with wax-based warm mix additives

Abstract Produced with fine crumb rubber (CR) particles and at demanding conditions, Terminal Blend (TB) asphalt binder is an alternative approach to incorporating CR from scrap tires into asphalt binders. It offers the advantages of convenient transportation, storage, and usage at asphalt mixture plants. In the study as presented in this paper, Sasobit® and Polyethylene (PE) wax were used as warm-mix additives to further modify the properties of TB asphalt binders. These additives are anticipated to reduce the production temperatures of TB asphalt mixtures, hence reducing fuel consumption and greenhouse gas (GHG) emissions in mixture production and reducing asphalt fumes in construction. It is also anticipated that the engineering performance of TB asphalt binders modified with such additives are not adversely affected. To gain a comprehensive understanding of TB asphalt binders modified with the two additives, a variety of laboratory tests were conducted, including storage stability, high temperature performance, low temperature performance, fatigue, and other basic rheological properties. The costs of producing TB asphalt mixtures with or without the additives were compared, using the conventional hot-mix asphalt mixtures as a reference. Energy consumptions and GHG emissions generated in mixture production were also evaluated. Actual field construction was performed using TB asphalt mixtures with Sasobit® and using conventional asphalt mixtures. Both aerosol and volatile organic compounds (VOCs) samples were collected at zones close to the loose mixtures and were analyzed. The two wax-based additives were found to enhance the storage stability and workability of the TB binders. The other engineering properties related to the use of wax-based additives are mixed. The selection of right type of additive depends on local climate conditions. While the costs of using the TB binders (with or without additives) are higher than the costs of using the base (neat) asphalt binder. Energy consumptions and GHG emissions in mixture production are reduced when the additives are used. Asphalt fumes generated from the base asphalt binder and the TB binder with Sasobit® are comparable. In general, the incorporation of wax-based additives into TB asphalt binder offers a cleaner way of using recycled crumb rubber.

Asphalt Fume Exposures by Pavement Construction Workers: Current Status and Project Cases

AbstractWorkers involved in asphalt pavement construction are exposed to asphalt fumes. The adverse health effects of asphalt fumes have long been recognized; however, there is still a lack of cons...

Characterization of fume composition and rheological properties of asphalt with crumb rubber activated by microwave and TOR

This paper studied asphalt fume chemical composition, rheological properties and microstructure of asphalt with crumb rubber (CR) activated by microwave and trans-polyoctenamer (TOR). To that end, asphalt fume was trapped through laboratory fume generation and capture system, which was subsequently analyzed by Gas Chromatography-Mass Spectrometry system (GC–MS). Moreover, the rheological behavior and microstructure of CR modified asphalt (CRMA) were characterized by dynamic shear rheometer (DSR) and FTIR. The GC–MS results indicated that CR activated by microwave and TOR reduces the contents of PAHs and sulfur compounds, implying the lower toxicological potential of fume. TOR has the greater effect of reduction in the toxicological species. The rheological results indicated that CR activated by TOR significantly improves modulus, zero shear viscosity (ZSV), and recovery ability of CRMA at high temperatures, which cause asphalt binder having the stronger resistance to rutting. The enhancement in thermo-mechanics is due to chemical cross-linking among TOR, rubber, and asphalt, which was verified by FTIR results. On the other hand, microwave treatment on CR affects high temperature performance of CRMA negatively in comparison to the untreated CRMA. However, microwave treatment leads to the faster stress relaxation response of CRMA, indicating the stronger resistance to thermal cracking.

Airborne emissions of asphalt/wax blends for warm mix asphalt production

During the asphalt heating process in the various stages of hot mix asphalt (HMA) production and paving operations a complex mixture of hydrocarbon aerosols, vapors and gases, generally composed of products of combustion, volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs), is emitted into the atmosphere. The reduction of these airborne asphalt emissions is a continuous issue and challenge for asphalt industry and road agencies. Thus, a number of new sustainable and cleaner technologies, generally referred to as warm mix asphalts (WMA), that significantly reduce the manufacturing and application temperatures, had been developed. Despite the great number of reported WMA methodologies, organic waxes are widely used for reducing the binder viscosity and for enhancing the asphalt mixture workability already at lower temperatures (90–140 °C).The manuscript presents a detailed laboratory investigation, based on headspace gas chromatography-mass spectrometry (HS-GC/MS) and photoionization detection (PID), which aimed to assess the content of VOCs and PAHs in the asphalt emissions, taking into account the effective contribution of binder or binder/wax blend. The characterization of asphalt fume composition has allowed the identification of more than 200 volatile compounds, highlighting at the same time a hierarchy of their appearance in relation to the temperature. The detection of the less volatile compounds was feasible only at temperatures higher than 160 °C, temperature range in which the HMA is generally produced. The study of the binary asphalt/wax mixtures highlighted the twofold way in which the waxes perform in reducing emissions: on the one hand they act as flow improvers (reduction of production and paving temperatures) and on the other as fume suppressants.

Health status assessment of workers during construction phase of highway rehabilitation projects around lahore, Pakistan.

The study focused on assessment of the health status of workers during construction phase of highway rehabilitation projects at six selected sites of N5 around Lahore, including Kala Shah Kaku, Muridke, Kamuki, Bhaipheru, Pattoki, and Okara. The study was based on multi-methods approach involving hazard identification through survey and checklist as well as a questionnaire for health status assessment and measurements of health parameters including peak expiratory flow rate (PEFR) and audiometric screening of 300 subjects. The study revealed non-congenial working conditions at the sites. Noise, vibrations, dust, asphalt fumes, poor work postures, and injuries were found to be major health hazards. PEFR of most of the workers was found to be significantly lower than the reference value. Average PEFR±SEM values were 187±5.1 l/min, 178±4.3 l/min, and 266±5.3 l/min in ground preparation workers, asphalt workers, and heavy vehicle drivers, respectively. The highest rate (29%) of hearing loss was recorded among heavy vehicle drivers. Musculoskeletal problems were found to be more common among ground preparation workers. Data revealed unsatisfactory health status of most of the workers. Direct relationship between health outcomes and the type of construction activities were observed. The current study focuses on the importance of including occupational health and safety plan in the execution phase of every developmental project that involves construction activities.

Acute toxicity evaluation of polycyclic aromatic hydrocarbons (PAHs) present in asphalt fumes in the alternative model Caenorhabditis elegans

Acute toxicity evaluation of polycyclic aromatic hydrocarbons (PAHs) present in asphalt fumes in the alternative model Caenorhabditis elegans

Toxic responses of different organs following occupational exposure to sub-threshold limit value levels of paving asphalt fumes

ABSTRACTThe main purpose of this study was to ascertain whether occupational exposure to asphalt fumes, under normal working conditions, is associated with any hepatotoxic, nephrotoxic, or hematotoxic response. This was a cross-sectional study in which 210 subjects (80 exposed and 130 reference subjects) were investigated. Using standard methods, atmospheric concentrations of total particulate and benzene-soluble fractions of asphalt fumes were measured. Additionally, urine and blood samples were taken from subjects for complete blood count, white blood cell differential test, urinalysis, and routine biochemical tests of kidney and liver function. Both groups were similar as far as their demographic variables and smoking habits were concerned. The levels of exposure to total particulate and benzene-soluble fractions were estimated to be 0.9 ± 0.2 and 0.32 ± 0.09 mg m−3, respectively (mean ± SD), both of which being lower than the existing threshold limit values. Statistically, significant associations between exposure to asphalt fumes and changes in most liver and kidney function tests and complete blood count parameters provided circumstantial evidence in favor of the notion that exposure to sub-threshold limit value levels of total particulate and benzene-soluble fractions is associated with early liver and kidney dysfunction as well as hematological disorders.

Airborne Exposures to Polycyclic Aromatic Compounds Among Workers in Asphalt Roofing Manufacturing Facilities

We studied exposure of 151 workers to polycyclic aromatic compounds and asphalt emissions during the manufacturing of asphalt roofing products—including 64 workers from 10 asphalt plants producing oxidized, straight-run, cutback, and wax- or polymer-modified asphalts, and 87 workers from 11 roofing plants producing asphalt shingles and granulated roll roofing. The facilities were located throughout the United States and used asphalt from many refiners and crude oils. This article helps fill a gap in exposure data for asphalt roofing manufacturing workers by using a fluorescence technique that targets biologically active 4–6 ring polycyclic aromatic compounds and is strongly correlated with carcinogenic activity in animal studies. Worker exposures to polycyclic aromatic compounds were compared between manufacturing plants, at different temperatures and using different raw materials, and to important external benchmarks. High levels of fine limestone particulate in the plant air during roofing manufacturing increased polycyclic aromatic compound exposure, resulting in the hypothesis that the particulate brought adsorbed polycyclic aromatic compounds to the worker breathing zone. Elevated asphalt temperatures increased exposures during the pouring of asphalt. Co-exposures in these workplaces which act as confounders for both the measurement of total organic matter and fluorescence were detected and their influence discussed. Exposures to polycyclic aromatic compounds in asphalt roofing manufacturing facilities were lower than or similar to those reported in hot-mix paving application studies, and much below those reported in studies of hot application of built-up roofing asphalt. These relatively low exposures in manufacturing are primarily attributed to air emission controls in the facilities, and the relatively moderate temperatures, compared to built-up roofing, used in these facilities for oxidized asphalt. The exposure to polycyclic aromatic compounds was a very small part of the overall worker exposure to asphalt fume, on average less than 0.07% of the benzene-soluble fraction. Measurements of benzene-soluble fraction were uniformly below the American Conference of Governmental Industrial Hygienists' Threshold Limit Value for asphalt fume.

Respiratory symptoms and lung functional impairments associated with occupational exposure to asphalt fumes.

Background: Controversy exists as to the potential of asphalt fumes to induce respiratory symptoms and lung functional impairments. Objective: To examine the respiratory effects, if any, of occupational inhalation exposure to asphalt fumes. Methods: In this cross-sectional study, 74 asphalt workers and 110 unexposed employees were investigated. The prevalence of respiratory symptoms among subjects was investigated by a standard questionnaire. Additionally, the parameters of pulmonary function were measured both, prior to exposure and at the end of work-shift. Furthermore, to assess the extent to which workers were exposed to asphalt fumes, total particulate and the benzene-soluble fraction were measured in different worksites. Results: The mean levels of exposure to total particulate and benzene-soluble fraction in asphalt fumes were estimated to be 0.9 (SD 0.2) and 0.3 (SD 0.1) mg/m3, respectively. Mean values of FEV1, both prior to the exposure (89.58% [SD 18.69%] predicted value) and at the end of shift (85.38% [SD 19.4%]), were significantly (p<0.05) smaller than those of the comparison subjects (93.88% [SD 13.93%]). Similarly, pre-shift (87.05 [SD 8.57]) and postexposure (89.95 [SD 6.85]) FEV1/FVC ratio were both significantly (p<0.01) lower than those of the unexposed employees (107.56 [SD 9.64]). Moreover, the prevalence of respiratory symptoms such as cough and wheezing in exposed employees were 41% and 42%, respectively. The corresponding values for comparison subjects were 10.0% and 3.6%, respectively (p<0.001). The pattern of changes in parameters of lung function in asphalt workers was consistent with that of chronic obstructive lung disease. Conclusion: Significant decrements in the parameters of pulmonary function as well as, a significant increase in the prevalence of respiratory symptoms in asphalt paving workers compared to their unexposed counterparts provided evidence in favor of a significant association between exposure to asphalt fumes and lung function impairments.

Experimental study on the reduction of fumes emissions in asphalt by different additives

Asphalt fumes contain a large number of toxic and hazardous substances. Three kinds of asphalt additives (Styrene butadiene styrene [SBS], activated carbon and layered double hydroxides) were investigated in this paper to reduce the emission of asphalt fumes. Aromatic hydrocarbons and polycyclic aromatic hydrocarbons were quantified by ultraviolet–visible spectrometer (UV–VIS). The suppressive effect of asphalt fumes by different additives with different ratios was evaluated by testing the total amount of PAHs. For the three asphalt additives used in this paper, SBS and activated carbon have better effects on fumes suppression, while the suppressive effect of layered double hydroxides is relatively poor. The optimal amount of layered double hydroxides, SBS and activated carbon for achieving the best control of fumes emission is 4, 4 and 5%, respectively.

Mechanism of fume suppression and performance on asphalt of expanded graphite for pavement under high temperature condition

Fume suppression mechanisms and the effect of expanded graphite on the performance of asphalt were studied by applying infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and comprehensive thermal analysis (TG, DSC). The experimental results confirm that asphalt which is mixed with expandable graphite will expand in the process of hot mix, and the expanded graphite layer will swell by the light component in the asphalt. The light component in the asphalt and PAHs adsorption on expanded graphite surface or part of the plug in the expanded graphite layer between plates made nucleation crystallization growth. And the Van der Waals force and the bonding of the lattice can effectively restrain the asphalt fume release. Meanwhile, the expanding agent with oxidative can spread into the asphalt, leading to asphalt oxygenated and plastic abate, while the ductility decreases. Expanded graphite, SBS modifier and environment-friendly plasticizers are used to composite modified asphalt. According to asphalt fume release experiment, normal test of asphalt performance, Brookfield viscosity test, RTFOT test and asphalt mixture tests (high temperature stability, low temperature stability, water stability), it has been proven that the modified asphalt’s performance is better than that of matrix asphalt and equivalent to that of SBS modified asphalt. Furthermore, it has good fume suppression effect.

82 High resolution computed tomography of the lungs of asphalt workers

Asphalt paving workers are exposed to ultrafine particles originating mainly from asphalt paving activities (asphalt fumes) and traffic exhaust. Studies hav ereported asphalt paving workers have more respiratory symptoms, airflow...

Lymphocyte DNA damage in Turkish asphalt workers detected by the comet assay

Asphalt has a highly complex structure and it contains several organic compounds including polycyclic aromatic hydrocarbons and heterocyclic compounds. In this study, comet assay was used to detect the DNA damage in blood lymphocytes of 30 workers exposed to asphalt fumes and 30 nonexposed controls. This is the first report on Turkish asphalt workers’ investigated DNA damage using the alkaline single cell gel electrophoresis (SCGE). The DNA damage was evaluated by the percentage of DNA in the comet tail (% tail DNA) for each cell. According to our results, workers exposed to asphalt fumes had higher DNA damage than the control group (p < 0.01). The present study showed that asphalt fumes caused a significant increase in DNA damage and the comet assay is a suitable method for determining DNA damage in asphalt workers.

Bio-monitoring for the genotoxic assessment in road construction workers as determined by the buccal micronucleus cytome assay

Buccal micronucleus cytome (BMCyt) assay monitors genetic damage, cell proliferation and cell death in humans exposed to occupational and environmental agents. BMCyt is used as an indicator of genotoxic exposure, since it is associated with chromosomal instability. There is little research on the occupational exposure among road construction workers for genotoxicity testing. In the present study, we evaluated MN frequencies and other nuclear changes, karyorrhexis (KR), karyolysis (KL), broken egg (BE), binucleate (BN), condensed chromatin cell (CCC), and picnotic cell (PC) in buccal mucosa cells of 40 road construction workers (twenty smokers and twenty non-smokers) and 40 control groups consisting of healthy persons (twenty smokers and twenty non-smokers). Microscopic observation was performed of 2000 cells per individual in both road construction workers and control group. In control and worker groups, for each person repair index (RI) was calculated via formula KR+L/BE+MN. The results showed a statistically significant increase in the frequency of MN in buccal epithelial cells of exposed group compared with control group (p<0.001). There is no significant difference between smokers and non-smokers for incidence of MN or nuclear changes and value of RI in exposed group. In road construction workers, RI is lower than the control group. There is a significant difference between workers and control group (p<0.001) for RI. Our data reveal that asphalt fumes during road paving operations are absorbed by workers and that asphalt fume exposure is able to significantly induce cytogenetic damage in buccal mucosa cells of workers after controlling some possible confounding factors, such as age, sex and smoking habits.In addition to determination of nuclear changes and the micronucleus, the determination of RI value presents a new approach to genotoxic bio-monitoring assessment studies of occupationally exposed population.

Study on Influencing Factors of Asphalt Fume Releasing and its Hazards

A large number of experiments were done in order to find out the main factors which have an influence on the asphalt flue production in asphalt road construction and to master its dangers. The results show that the asphalt flue production varies with heating temperature, heating time, the asphalt thickness and stirring rate significantly. accordingly these are the main factors which influence the asphalt flue production. Further analysis by means of UV spectrophotometer and liquid chromatography shows that the asphalt flue contains serious harm to human body, such as aromatic compounds, alkanes, and sulfur heterocyclic compounds and other substances. therefore some steps should be taken to inhibit the production of asphalt flue for reducing the hazards to construction workers.

Lymphocyte DNA damage in Turkish asphalt workers detected by the comet assay

Asphalt has a highly complex structure and it contains several organic compounds including polycyclic aromatic hydrocarbons and heterocyclic compounds. In this study, comet assay was used to detect the DNA damage in blood lymphocytes of 30 workers exposed to asphalt fumes and 30 nonexposed controls. This is the first report on Turkish asphalt workers’ investigated DNA damage using the alkaline single cell gel electrophoresis (SCGE). The DNA damage was evaluated by the percentage of DNA in the comet tail (% tail DNA) for each cell. According to our results, workers exposed to asphalt fumes had higher DNA damage than the control group (p<0.01). The present study showed that asphalt fumes caused a significant increase in DNA damage and the comet assay is a suitable method for determining DNA damage in asphalt workers.