Faculty Advisor or Committee Member

Paul Mathisen, Committee Member

Faculty Advisor or Committee Member

John Bergendahl, Advisor

Identifier

etd-042519-094531

Abstract

Polycyclic aromatic hydrocarbon (PAH) compounds, which are common to coal tar and coal-tar-based products, are ubiquitous environmental contaminates with carcinogenic effects to human health and aquatic life. Transport of PAHs via solid phase particulate motion, gaseous phase volatilization, and aqueous phase dissolution into urban waterbodies of PAH compounds from coal-tar-based pavement sealant products has been studied. Pavement rejuvenators are products applied to increase the usable life of pavement. Coal-tar-based rejuvenators contain a significantly larger mass fraction of coal-tar with respect to coal-tar-based sealants, but pavement rejuvenators have not been as extensively studied as pavement sealants. Chemical analysis of detached pavement material treated with coal-tar-bases, asphalt-based, and bio-based rejuvenators was conducted with gas chromatography – mass spectrometry (GC/MS) analysis for 16 PAH compounds and two aromatic heterocyclic organic compounds following extraction with methylene chloride. Detached pavement material was collected from 19 simulated asphalt surface abrasion experiments that used a model mobile load simulator (MMLS) test apparatus that replicated surface challenges from vehicular traffic. The MMLS test apparatus configuration allowed asphalt disc samples treated with different rejuvenation products, to be tested and for detached material to be collected and quantified prior to GC/MS analysis. Test cases evaluated the influence of rejuvenation product type and cure time, as well as the effect of sand application (simulating sand application during slippery winter storm conditions) had on detached particulate and ultimate PAH compound loading. The average mass of particulate detachment from samples following a 48 hour cure time, for the asphalt-based and coal-tar-based rejuvenator products were 0.347 g and 0.480 g, respectively. This mass of detached material was lower than that from pavement treated with bio-based rejuvenator and the control (not treated), which had 4.858 g and 2.567 g of detached particulate material, respectively. When the product cure time was increased to three weeks, which was significantly long enough to capture effects of compound volatilization, average particulate detachment increased to 0.882 g for the coal-tar-based rejuvenator and decreased for the bio-based rejuvenator to 2.600 g. Six tests performed with a single application of winter storm sand after a 48 hour product cure time showed an increase in average particulate detachment to 1.450 g and 0.617 g for pavement treated with the asphalt-based and coal-tar-based rejuvenators, respectively. Conversely, under the same conditions, a reduction in average detached particulate to 3.749 g was observed for the bio-based product. Detached particulate material quantities for each test case were used with the respective cumulative concentration of 16 PAH compounds quantified to make an assessment on the potential PAH compound contamination via solid phase particle transport. The average PAH compound concentration in particulate detached from pavement treated with a coal-tar-based rejuvenator was 3062.8 mg PAH per kg of particulate. This was an order of magnitude higher than the average PAH concentration measured in particulate detached from the two control pavement samples and the two asphalt-based samples after a 48 hour cure time, which were 322.1 and 508.1 mg PAH per kg detached particulate, respectively. PAH compound concentrations were also normalized by the surface area of pavement treated with a rejuvenator to determine the potential PAH compound contamination per unit area. Normalized results for each rejuvenator type were averaged to make an overall evaluation of the potential rejuvenator specific PAH compound loading. The coal-tar-based, bio-based, and asphalt-based rejuvenators had a normalized cumulative solid-phase PAH compound release of 2.35, 0.88, and 0.17 mg PAH per square foot of pavement rejuvenated, respectively. In addition, carbazole was quantified in all pavement samples treated with the coal-tar-based rejuvenator at an average concentration of 125.6 mg carbazole per kg detached particulate. Acridine was quantified in detached particulate from five of seven coal-tar-based test performed at an average concentration (excluding non-detection samples) of 42.1 mg acridine per kg detached particulate.

Publisher

Worcester Polytechnic Institute

Degree Name

MS

Department

Civil & Environmental Engineering

Project Type

Thesis

Date Accepted

2019-04-23

Accessibility

Unrestricted

Subjects

Coal Tar, PAHs, Pavement Rejuvenators, Polycyclic Aromatic Hydrocarbon

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