Hani H. Titi

The use of recycled pavement materials in transportation infrastructure projects has contributed positively to maintaining a sustainable flow of construction materials and sources. Geotechnical properties of recycled pavement materials play a major role in the suitability of such materials for use in civil infrastructure. This study aimed at evaluating the properties of recycled concrete aggregates (RCA) and reclaimed asphalt pavements (RAP) used as base layer materials in existing hot mix asphalt pavements (with service life of more than 8 years) and comparing them with virgin crushed aggregate (CA) base materials of similar service life. Coring of flexible pavement surface layers at 18 pavement sites was performed to expose the base course layer materials for sampling and testing. Then, the dynamic cone penetrometer (DCP) test was conducted in which the cone penetrated through base layers to the subgrade when possible. Thereafter, base materials were retrieved from the pavement sites for laboratory testing and evaluation. Laboratory tests consisted of particle size analysis, specific gravity and absorption, and Micro-Deval abrasion. Analysis of the particle size distribution showed the presence of high sand size fractions in both RCA and RAP base materials compared with virgin CA base materials. This indicated the recycled materials were crushed/milled to smaller size fractions or degraded under freeze-thaw cycles and traffic loads during the pavement’s service life, or both. The RCA base materials exhibited the highest absorption and mass loss in the Micro-Deval test. The DCP test results were used to predict California bearing ratio (CBR) and resilient modulus (M_r) of base materials. The predicted CBR and resilient modulus of the recycled base materials showed that RCA, RAP, and CA all had comparable strength and modulus values that were high. The investigated recycled RCA and RAP aggregates possessed properties that are comparable with the properties of the virgin CA.

There has been an increased interest in using reclaimed asphalt pavement (RAP) aggregates as a base course in Wisconsin for the offered economic and environmental benefits. Laboratory studies showed that RAP can have resilient modulus values higher than typical natural aggregates, and can also have higher durability, especially in freeze–thaw cycles. However, it is also recognized that RAP exhibits temperature sensitivity and larger permanent deformations than natural aggregates. How these characteristics manifest themselves in the northern U.S. climates can only be assessed by long-term observation of field performance. Wisconsin Department of Transportation (WisDOT) has been using RAP as a base course for over 30 years. The qualitative assessment of WisDOT roads constructed with RAP showed they are performing adequately. However, this impression has not yet been verified quantitatively. This paper presents a quantitative assessment and comparisons for field performance of pavement test sections constructed with RAP and natural crushed aggregate (CA) base course layers in Wisconsin. The performance was evaluated using pavement distress surveys of roadways containing RAP and CA, falling weight deflectometer (FWD), dynamic cone penetrometer (DCP) tests, and analysis of WisDOT’s available data. Based on the field evaluation, the performance of the hot mix asphalt (HMA) pavements with RAP was found adequate and comparable to those with CA base course layers. A recommendation was given that WisDOT shall continue the practice of using RAP in base course layers of HMA pavements, given proper quality checks for materials, and proper quality control/quality assurance measures being applied during construction.

The goal of this study is to develop a framework for the life-cycle understanding of flexible pavements. New advancements in data analytics allow for the utilization of pavement life-cycle data (historical, environmental, and structural) to evaluate the effects of material, construction, and loading parameters on the in-service performance of the pavements. In this study, the data were georeferenced to establish a connection between pavement parameters such as construction and production quality factors, traffic loading, material properties, pavement structure, and climate conditions to the long-term performance of flexible pavements. The data used in this paper were sampled from the Wisconsin Department of Transportation (WisDOT). Data were filtered to include pavement sections of comparable traffic load and environmental conditions to avoid potential bias in the analysis. Information on 42 highways with a total length of 260.5 mi was collected and analyzed for this study. Pavement deterioration metamodels were developed on high-resolution data using three machine learning (ML) techniques. For the purpose of construction of the metamodels, ML techniques including decision tree regression (DTR), random forest (RF), and gene-expression programming (GEP) were utilized by using coded subroutines in Python. The outcomes of DTR, RF, and GEP approaches showed promising results in the modeling of pavement performance by considering the effects of mix production quality factors such as air voids of the mixture (VA), individual lots voids in mineral aggregates (VMA), in-place density of asphalt mixture (%Gmm), asphalt content (AC), surface thickness, and age of pavements. This approach provides a basis for comprehensive life-cycle evaluation of the highway network without disrupting the state of practice. It relies on connecting data already being collected by the transportation agencies. The relational connection of such data allows for a pavement management system that is capable of continuously reflecting the pavement network performance on design, control, and maintenance activities.

Geogrids are a class of geosynthetic materials made of polymer materials with widespread transportation, infrastructure, and structural applications. Geogrids are now routinely used in soil stabilization applications ranging from reinforcing walls to soil reinforcement below grade or embankments with increased potential for remote-sensing applications. Developments in manufacturing procedures have allowed new geogrid designs to be fabricated in various forms of uniaxial, biaxial, and triaxial configurations. The design flexibility allows deployments based on the load-carrying capacity desired, where biaxial geogrids may be incorporated when loads are applied in both the principal directions. On the other hand, uniaxial geogrids provide higher strength in one direction and are used for mechanically stabilized earth walls. More recently, triaxial geogrids that offer a more quasi-isotropic load capacity in multiple directions have been proposed for base course reinforcement. The variety of structures, polymers, and the geometry of the geogrid materials provide engineers and designers many options for new applications. Still, they also create complexity in terms of selection, characterization, and long-term durability. In this review, advances and current understanding of geogrid materials and their applications to date are presented. A critical analysis of the various geogrid systems, their physical and chemical characteristics are presented with an eye on how these properties impact the short- and long-term properties. The review investigates the approaches to mechanical behavior characterization and how computational methods have been more recently applied to advance our understanding of how these materials perform in the field. Finally, recent applications are presented for remote sensing sub-grade conditions and incorporation of geogrids in composite materials.

Aggregates selected for Wisconsin transportation infrastructure must withstand harsh service conditions. In this paper, results of comprehensive statistical analyses on three sets of aggregate test data (two from Wisconsin and one nationally) are discussed. This included a database containing 2,052 sets of quality control aggregate tests from various construction projects in Wisconsin, an earlier Wisconsin aggregate research study (69 data sets), and a set of test results of aggregates from different parts of the United States and Canada (111 data sets). In addition, tests on 12 types of marginal or poor Wisconsin aggregates (as characterized by the state) were performed. The study objectives were to evaluate relevant statistical parameters for various aggregate test results and identify correlations among them. The possibility of predicting the outcomes of two tests [micro-Deval (MD) and unconfined freeze-thaw (UFT)] from other more common test results was studied. Multiparameter logistic regression analyses indicated that the micro-Deval test’s pass/fail outcomes could be predicted when results of other commonly performed tests were known. However, the outcome of the UFT test could not be forecast using results of other tests.

The US Environmental Protection Agency (EPA) proposed a new “Effluent Limitations Guidelines” for construction site runoff management in 2009, which required that stormwater effluents be sampled and that the daily average turbidity must not exceed 280 NTU. Although this numeric limitation was removed from its final amendment in 2014, the EPA still reserves the right to reconsider it in future regulations. To better understand the limits of the turbidity in the effluent, stormwater runoff samples were collected at different times during storms from five highway construction sites in Wisconsin. Measured turbidity in grab samples taken during or after storms ranged from 20 to 2,300 NTU. Sample analyses showed that a power law relation can well describe the correlation between turbidity and the total suspended solids in construction site effluent. Automated turbidity sampling devices were deployed at outfalls of four selected sites to continuously record the time series of turbidity. Statistical analyses were conducted on turbidity data and the precipitation time series. Both the peak and the maximum daily average turbidity values were found to be linearly correlated with the total precipitation, while they are not correlated with either the average or the peak rainfall intensity. It is also demonstrated that a characteristic unit runoff turbidity function, which represents the response of turbidity with respect to a unit precipitation depth, can be reconstructed from a measured time series. Reconstruction of the turbidity response function and the observed statistical correlations suggest that it is possible to develop models to predict the daily maximum turbidity and the total turbidity load of construction site runoff for designated storm events. Models of this kind are valuable for future management practice and for evaluating new regulation policies.

With continuing increases in the number of Oversize-Overweight (OSOW) vehicle permits issued in recent years, the management and analysis of OSOW permit data is becoming more inefficient and time-consuming. Large quantities of archived OSOW permit data are held by Departments of Transportation (DOTs) across the United States, and manual extraction and analysis of this data requires significant effort. In this paper, the authors present a new framework for analyzing Wisconsin’s historic OSOW permit program data. This framework provides an interactive, web-based interface to query the OSOW permit data, link OSOW records to geospatial data features, and dynamically visualize query results. The web-based interface offers scalability and broad accessibility to the data across different DOT divisions, and use cases. Furthermore, a user survey and heuristic evaluation of the interface demonstrate the project’s utility, and identify goals for future system development.