Waterborne paint is the most common marking material used throughout the United States. Because of budget constraints, most transportation agencies repaint their markings based on a fixed schedule, which is questionable in relation to efficiency and economy. To overcome this problem, state agencies could evaluate the marking performance by utilizing measured retroreflectivity of waterborne paints applied in the National Transportation Product Evaluation Program (NTPEP) or by using retroreflectivity degradation models developed in previous studies. Generally, both options lack accuracy because of the high dimensionality and multi-collinearity of retroreflectivity data. Therefore, the objective of this study was to employ an advanced machine learning algorithm to develop performance prediction models for waterborne paints considering the variables that are believed to affect their performance. To achieve this objective, a total of 17,952 skip and wheel retroreflectivity measurements were collected from 10 test decks included in the NTPEP. Based on these data, two CatBoost models were developed with an acceptable level of accuracy which can predict the skip and wheel retroreflectivity of waterborne paints for up to 3 years using only the initial measured retroreflectivity and the anticipated project conditions over the intended prediction horizon, such as line color, traffic, air temperature, and so forth. These models could be used by transportation agencies throughout the United States to 1) compare between different products and select the best product for a specific project, and 2) determine the expected service life of a specific product based on a specified threshold retroreflectivity to plan for future restriping activities.
One of the emerging solutions to enhance the durability of asphalt pavements is the use of a French asphalt mix known as “High-Modulus Asphalt Concrete (HMAC).” This mix uses a hard asphalt binder, high binder content (about 6%), and low air voids content as compared with Superpave mixtures. The key objective of this study was to develop a cost-effective HMAC mixture using crumb rubber and local materials in Louisiana. To achieve this objective, four HMAC mixtures were prepared using two asphalt binders (PG 82-22 and PG 76-22 plus 10% crumb rubber) and two Reclaimed Asphalt Pavement (RAP) contents (20% and 40%); additionally, a conventional Superpave mixture in Louisiana was prepared as a control mixture. The laboratory performance of these five mixtures was evaluated in relation to workability, dynamic modulus, rutting resistance, and cracking resistance. The AASHTOWare Pavement ME Design software was also used to estimate the long-term field performance of these mixtures. Results indicated that the HMAC mixture prepared with 10% crumb rubber and 20% RAP successfully met the French mix design specifications for HMAC and LaDOTD specifications. This HMAC mix outperformed the control Superpave mix in relation to dynamic modulus, rutting resistance, and cracking resistance. Additionally, this HMAC mixture can reduce the required asphalt thickness by 1.5 or 2 in. based on traffic level. The cost-effectiveness analysis indicated that this HMAC mixture was more cost-effective than conventional Superpave mixtures in Louisiana. In addition, this mixture is environmentally friendly as it can reduce the disposal of scrap tires in landfills.
There is growing interest in sustainable road pavement technologies to protect the environment and provide economic benefits. Post-consumer recycled (PCR) plastics are considered for construction to address the threat of plastic waste materials (PWM) and to improve sustainability. Asphalt pavement construction is highly considered for PWM recycling due to its large daily production. The purpose of this study is to investigate the performance of asphalt mixture containing PWM, specifically high-density polyethylene (HDPE), and compare its performance with two conventional mixtures. Three asphalt mixtures were considered: (1) mixture with asphalt binder PG 76-22 (SBS-modified); (2) mixture with asphalt binder PG 70-22 (SBS-modified); and (3) mixture with binder PG 67-22 and 3% HDPE (the plastic mixture). The rheological properties of the modified asphalt binders and the performance of the modified asphalt mixtures were evaluated. The long-term field performance of the pavements was modeled using AASHTOWare software (v.1.1.6) for the three mixtures considered. The results showed that all the mixtures were able to comply with the cracking threshold specified by the Louisiana Department of Transportation and Development (LaDOTD) for high-traffic volume roads. In addition, the plastic asphalt mixture showed similar performance to the one containing PG 70-22 (SBS-modified) asphalt binder.
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