Ashley Buss

Highway Infrastructure Health Monitoring Using Micro-Electromechanical Sensors and Systems (MEMS)

AbstractThe development of novel “smart” structures by embedding sensing capabilities directly into the construction material during the manufacturing and deployment process has attracted significant attention in autonomous structural health monitoring (SHM). Micro-electromechanical systems (MEMS) provide vast improvements over existing sensing methods in the context of SHM of highway infrastructure systems, including improved system reliability, improved longevity and enhanced system performance, improved safety against natural hazards and vibrations, and a reduction in life cycle cost in both operating and maintaining the infrastructure. Advancements in MEMS technology and wireless sensor networks provide opportunities for long-term, continuous, real-time structural health monitoring of pavements and bridges at low cost within the context of sustainable infrastructure systems. Based on a comprehensive review of literature and vendor survey, the latest information available on off-the-shelf MEMS devices,...

Reporting Results from the Hamburg Wheel Tracking Device

As the list of states adopting the Hamburg wheel tracking device continues to grow, there is a need to evaluate how the results are used. AASHTO T-324 does not standardize the analysis and reporting of test results. Furthermore, the processing and the reporting of the results of manufacturers are not uniform. This inconsistency is partly the result of the variation of agency reporting requirements. Some requirements include only the midpoint rut depth; others include the average across the entire length of the wheel track. No guidance is given when the stripping infection point (SIP) is reported. To eliminate bias in reporting, statistical analysis was performed on more than 135 test runs on adjoining gyratory specimens. Measurement location was found to be a source of significant variation for rut depth in the Hamburg wheel tracking device. This variation was likely the result of the nonuniform wheel speed across the specimen, geometry of the specimen, and air void profile. Eliminating this source of bias when rutting results are reported is feasible although the feasibility depends on the average rut depth at the final pass. When the results of a test that has an average rut depth of less than 12 mm at the final pass is reported, the average of the measurements along a 6.4-in. path beginning at 0.5 in. from the specimen edge nearest the gear housing should be reported. When the average final-pass rut depth is greater than 12 mm, it is reasonable to report the average of the measurements just off the center of the rutting track along a 3.2-in. path beginning at 2.1 in. from the specimen edge nearest the gear housing. SIP values were also analyzed. It is reasonable to report the average of the SIP values across all locations while calculated values measured more than 2 in. from the specimens edge are discarded and for cases in which the ratio of the stripping slope to creep slope exceeds 2.0. Validation is needed for multiple machines.

Investigation of Isosorbide Distillation Bottoms as a Bio-Based Warm-Mix Additive

AbstractBiorefineries are increasing in number and size and include products based on food, energy, and chemicals. Depending on size and targeted products, biorefineries produce distillation bottoms with surfactant characteristics in sufficient quantities that can be used as a warm-mix asphalt (WMA) technology. Isosorbide distillation bottoms (IDB), having amphiphilic properties much like a classical ionic surfactant, are derived as coproducts of bio-based chemical production and show potential for reducing mixing and compaction temperatures as well as having low-temperature performance grade (PG) benefits. The objective of this paper is to evaluate the performance and potential of IDB as an asphalt additive through asphalt binder testing and mixture testing. Binder gradations were conducted for multiple binders at several dosage rates to verify compatibility with various petroleum crude sources and determine the optimum dosage level. Testing indicates promising results and shows an optimal dosage rate at...

Mechanistic empirical performance of warm-mix asphalt with select bio-derived additives in the Midwestern United States using AASHTOWare pavement ME design

An industry-wide emphasis on sustainable asphalt practices has given rise to increasing use of warm-mix asphalt (WMA) technologies. WMA reduces both binder viscosity and mixing and compaction temperatures by 20–55°C during the asphalt mix production and laydown process. This research investigates several bio-derived WMA additives that act as chemical modifiers with surfactant properties. Two established additives derived from the forest products industry are studied as well as a WMA additive in development that is derived from corn. The objective of this research is to use the new AASHTOWare Pavement ME Design to compare the established forest product WMA additives with the new WMA corn-derived additive that is in development. Using binder and mix test results as input values in AASHTOWare Pavement ME Design, predicted pavement performance was evaluated for sensitivity to different climatic conditions seen in the Midwestern United States. Results indicate that the climatic conditions have a larger impact on the pavement performance as compared to the impact from binder type and additive choice. The corn-derived WMA additive was similar to the other established WMA additives and HMA control group showing similar pavement performance predicted by the AASHTOWare Pavement ME Design.

Assessment of Composite Pavement Performance by Survival Analysis

AbstractThe main objective of this paper is to identify the most appropriate rehabilitation method for composite pavements and to evaluate the influence of different factors for the reflective crack development in composite pavement by survival analysis. Four composite pavement rehabilitation methods are evaluated: mill and fill, overlay, heater scarification, and rubblization. Survival analysis is used to evaluate the four methods using three pavement performance indicators: reflective cracking, international roughness index (IRI), and pavement condition index (PCI). Rubblization can significantly retard reflective cracking development compared with the other three methods. No significant difference for PCI is seen in the survival analysis for the four rehabilitation methods. Heater scarification shows the lowest survival probability for both reflective cracking and IRI, whereas overlay results in the poorest overall pavement condition based on PCI. Parametric survival models are employed to further anal...

Long-Term Evaluation of Cold-in-Place Recycling and Factors Influencing Performance

AbstractCold in-place recycling (CIR) is a type of rehabilitation strategy that has shown to significantly improve the condition of flexible pavements with adequate subgrade support. The process in...

Warm Mix Asphalt Performance Modeling Using the Mechanistic-Empirical Pavement Design Guide

Warm mix asphalt (WMA) is a cost effective means for reducing the mixing and compaction temperature of hot mix asphalt (HMA). These additives, which come in several forms, reduce the mixing and compaction temperatures by approximately 30°C. The challenge for researchers has been determining how the additives impact or change traditional HMA mixes. The purpose of this research is to use collected laboratory data as inputs into the Mechanistic-Empirical Pavement Design Guide (MEPDG) to determine if there are statistically significant differences in the amount of pavement cracking when comparing HMA and WMA. The MEDPG is a model that has been developed into software for the purpose to provide state-of-the-practice pavement design for both new and rehabilitated pavement structures. The pavement design includes site condition parameters such as traffic, climate, subgrade, and existing pavement conditions in the case of rehabilitation. The MEPDG evaluates a proposed design for various distresses such as rutting, fatigue cracking, longitudinal cracking, transverse cracking, and roughness. Samples from field produced WMA mixes have been tested and material information has been collected and statistically analyzed over a period of several years. Data analysis showed some statistically significant differences in laboratory dynamic modulus (E*) data when comparing HMA control mix with the WMA mix. This study will use the laboratory measured E* as input into the MEPDG model to predict the pavement cracking in order to determine if there are differences in the pavement distresses. Within the design inputs, various factors can be manipulated such as various traffic loading and pavement thickness. Changing these inputs show which site condition variables have the most impact on pavement performance, how pavement distresses may differ when comparing HMA and WMA and how this translates to differences in pavement life.

Life-Cycle Cost Adjustment Factors in Alternate Design/Alternative Bid Pavement Bids: Added Value or Added Controversy?

Alternative design/alternative bids (ADAB) provides a mechanism for the asphalt and concrete paving industries to compete for the same paving project. It operates on the principle of the market pricing of each material determining which is most economical when the bids are opened, rather than selecting the pavement type during design based on a life-cycle cost analysis (LCCA). This paper reviews including LCC-based bid adjustment factors in the ADAB award decision. Data are from a survey that received responses from 40 U.S. Departments of Transportation (DOT) and the Canadian province of Ontario, and a content analysis of 55 ADAB project outcomes in 13 U.S. states and three Canadian provinces. Seven algorithms in use to calculate an ADAB bid adjustment factor were found, and six U.S. DOTs that award ADAB projects without an adjustment factor. The paper finds that the adjustment factor formula rarely influences the award decision and, generally, the pavement type with the lowest bid cost wins with or without the adjustment factor. The paper models the ADAB process in financial terms as an exercisable commodity option that accrues value from the differential rates of volatility between asphalt and concrete. It concludes that an LCC-based bid adjustment factor complicates the award process, creating potential for controversy over what the factor inputs are, and does not add value over bidding the pavement types head to head and awarding to the low bidder. The ADAB process increases the number of bidders and reduces unit bid prices for both pavement types.

Layer coefficients of cold in-place recycled layers from performance data

ABSTRACT With cold in-place recycled (CIR) pavements becoming an increasingly popular treatment for pavement life extension, it is important for local agencies to have data that justifies the design parameters that influence the effectiveness of such treatments. Studies have shown that the effectiveness of CIR depends on its milling depth, and in order for agencies to better decide the pavement design, depth of CIR to be milled and placed, the authors have developed a procedure to back-calculate the structural layer coefficient of CIR layers based on performance data, in order to evaluate their structural capacity. This paper attempts to establish a relation between the structural capacity of the CIR layer and the international roughness index (IRI) of the pavement over time, using the results of previous research determining a definite differential between the IRI of pavements with different CIR thicknesses.

Performance characteristics of epoxy asphalt paving material for thin orthotropic steel plate decks

ABSTRACT Early pavement distress caused by heavy traffic is frequently observed on bridges with relatively thin decks of orthotropic design, particularly in hot climates. This study investigates the possible use of epoxy asphalt to stiffen the thin deck/pavement composite, minimise deflection and ultimately fatigue failure. Three different epoxy asphalt binders were used and two pavement mix designs were employed. The binder and pavement mixture properties were evaluated by direct tensile and pull-off strength test on the binder, Marshall test of the paving mixture and flexural fatigue tests of paving mixture on steel plates. Test results show that a relatively high modulus binder and a relatively stiff pavement can effectively reduce the composite’s deflection and improve fatigue resistance on a relatively thin steel plate. Binder adhesion to the aggregate in the composite seems to play a pivotal role and the strength of this bond may have a close relationship with the stiffness of the pavement.