Pavement System Research Articles

Evaluation of Permeable Pavement Systems for Removing Heavy Metals from Stormwater

This study examines a modified permeable pavement system (PPS) for enhanced heavy metal attenuation from stormwater. A laboratory model consisting of six PPS columns has been tested under varying rainfall intensities. The PPS structures are arranged based on the following hypotheses for enhancing heavy metal attenuation: (i) addition of a natural zeolite layer in the subbase for promoting heavy metal attenuation by adsorption and ion exchange; (ii) addition of a bark chip layer as an organic carbon source for promoting biosorption of heavy metals; (iii) maintaining a saturated zone in order to maintain the required humidity level and decrease the level of oxygen for increased biodegradation; and (iv) inclusion of thin sand layers to restrict the transport of oxygen to create an anoxic zone in the PPS and to enhance filtration. Successful treatment of metals such as Ba, Co, Mn, Ni, and Zn has been observed under various rainfall conditions using a conventional PPS. The rainfall intensity greatly influences the attenuation of Al, Cr, Cu, Mo and Sr. During heavy rains through the conventional PPS structure, chromium is found to be leached back into the infiltrate. The results indicate that by changing the subbase material and layer setting, biosorption of heavy metals can be encouraged in the PPS structure. The results of this study suggest that the PPS structure be amended by adding into its subbase a saturated region, an organic carbon donor and thin sand layers for enhanced heavy metal attenuation. Compared to the conventional structure, the proposed structure reduces Cr desorption and improves the attenuation of Al, Cu and Mo.

Suitability of rubberised oil palm shell layers to stabilise concrete block pavement systems

ABSTRACT This study focuses on evaluating the response of concrete block pavement (CBP) reinforced with rubberised oil palm shell (ROPS) layers when subjected to vehicular loads using laboratory experiments and finite element (FE) simulations. The key parameters considered in this study are the sand bed thickness, oil palm content in ROPS layers, embedment depth of ROPS layers, and vehicle velocity. The dynamic loads due to the vehicular movement were generated using a real-time road unevenness signal. Outcomes from the lab-scale 1g experiments and FE simulations were expressed as displacement and acceleration responses in the frequency domain. CBP sections with sand bed thicknesses of 10mm and 70mm were found to yield high surface deflection and acceleration values, both with and without ROPS reinforcements. CBPs reinforced with the ROPS layer having 20% OPS content demonstrate the best performance compared to ROPS layers made with 5% and 10% OPS contents. Further simulations show that the ROPS layers at an optimum embedment depth of 180mm from the surface in the CBP profile can significantly reduce the unacceptable levels of vibration. To this end, this preliminary research attempts the possible reengineering of oil palm shells and ascertains the suitability of ROPS reinforcements in stabilising CBP−soil systems.

Continuous Hydrologic Modeling of a Parking Lot and Related Best Management Practices with PCSWMM

AbstractPermeable pavements are a green infrastructure stormwater management practice that can serve as a functional component of the site design. However, previous field studies suggest high uncertainty in the parameters used for performing hydrologic calculations for permeable pavements. The Environmental Protection Agency (EPA) Storm Water Management Model (SWMM) within the PCSWMM software package was used to simulate the hydrologic dynamics of a parking lot that is 25% covered with permeable interlocking concrete pavers in Auburn, AL. The model was calibrated to field observations of water level at two points where the pavement system outflows to a bioretention basin and rainfall data from a nearby weather station. The use of the Curve Number (CN) method within SWMM resulted in good prediction of pavement outflow by the calibrated model, with R2 and Nash‐Sutcliffe model efficiency both greater than 0.8, except where issues with precipitation data coverage occurred. This demonstrates that permeable pavements can be modeled as a land cover type rather than as detention storage. The calibrated value of the runoff CN for permeable pavement was 60, much lower than what is recommended in many design guidelines for the underlying soil type at the research site, which is hydrologic soil group B. Based on evaluation of alternative model scenarios, the permeable pavement reduced runoff by 11‐38% across contrasting rain events.

Triaxial resilient modulus regression models for cold recycled asphalt mixtures

Cold recycled asphalt mixtures (CRAMs) may present a compressive resilient modulus dependent on the stress state. Currently, there is no widespread consensus on a triaxial resilient modulus (TxRM) model for CRAM analysis. A widely accepted TxRM model would favour the analysis of CRAM’s layered pavement systems. This paper assessed the adequacy of different TxRM models of CRAM’s specimens with different compositions, aggregate gradation and physical characteristics. Based on the literature, three different TxRM models were selected. The models’ non-linear estimation was performed through Levenberg–Marquardt algorithm. Model selection analysis was based on residuals square sum root (RSSR) assessment. Ni et al.’s model was found to be the most adequate for CRAM’s TxRM modelling based on RSSR analysis. The model selection was done regardless of aggregate gradation, binder type/content, air void content, RAP content, TxRM values range, active filler type and curing time of the tested specimens.

AEM analysis of asphalt pavement on PC bridge under the coupling effect between impact from ruptured vertical PC bars and temperature

The resistance of asphalt pavement against impact loading from corrosion-induced ruptured vertically tightened PC bars in PC bridges is critical for traffic safety. When vertically tightened PC bars in PC girders rupture, they protrude from the anchorage section and damage the asphalt pavement, which may cause severe accidents. In this study, the performance of a two-layered asphalt pavement system under the coupling effect between impact and temperature, with the impact caused by a vertically tightened PC bar with 4,408 J impact energy at 50 °C and 0 °C, was investigated. A 3D Applied Element Method (AEM) model was developed for simulating asphalt pavement at 50 °C and 0 °C under 4,408 J impact energy. The numerical simulations were verified based on the experimental results. The numerical simulation results showed that the asphalt pavement system used in this study at 50 °C and 0 °C can withstand 4,408 J impact energy. Further, AEM numerical simulation with appropriate modeling demonstrated the effectiveness of an asphalt pavement system with appropriate material and thickness in preventing protrusion of PC bar.

Evaluation of Flood-Vulnerable Pavement Network in Support of Resilience in Pavement System Management

Transportation systems play a pivotal role in the nation’s economic and societal development. Transportation assets, such as pavements and bridges, are inevitably subject to the effects of climate and environment. These stressors mainly include flood, precipitation, heat, wildfire, and wind. Specifically, more extreme weather events, such as hurricanes and snowstorms, have occurred in recent years. This requires stakeholders to better prepare transportation infrastructure resilience in planning, design, construction, and management. Its importance is manifested through nationwide policy and state-level practice. For example, in Bipartisan Infrastructure Law, the FHWA directs all state DOTs to incorporate resilience in their transportation asset management plans. A critical element in resilience is to evaluate the effect of climatic or environmental stressors on facilities’ performance. This study examines the impact of flood on the TxDOT-managed pavement network. It proposes a method to evaluate the flood-vulnerable pavement network in the context of resilience. First, the GIS tool is used to overlap a 100-year frequency flood with the road network to identify weak pavement sections subject to flood risk. Second, a simulation is run to determine sections affected by flood over a 10-year analysis horizon. Then, different deterioration models are used to predict the network-level pavement performance, to reflect (1) normal deterioration without flood, (2) optimistic accelerated deterioration under flooding, and (3) pessimistic accelerated deterioration under flooding. It is found that the network-level pavement will experience varying levels of performance reduction, owing to a 100-year flood impact. The quantified performance change can serve to enhance infrastructure resilience preparation for more reliable pavement system management.

Mechanistic Assessment of Flexible Pavements in Wisconsin Using Traffic Speed Deflectometer

The traffic speed deflectometer (TSD) has been gaining interest for pavement management practices, as it can continuously collect deflection data at traffic speed without requiring traffic control. TSD data have been typically used to provide an estimate of the structural condition of pavements with a limited range of significant parameters considered in the analysis. To date, limited studies have been conducted in or for cold regions to consider the potential use of TSD data for pavement structural assessment. This study aimed to bridge this gap by developing a twofold approach to: (1) mechanistically characterize the structural integrity and remaining life of pavements; and (2) compare TSD and falling weight deflectometer (FWD) data collected in the field, considering the features of pavement facilities in Wisconsin. A field testing plan was developed to characterize the site-specific features of eight representative pavement sections, with a total length of about 30 mi and distinct pavement structures, truck traffic patterns, and climatic conditions. The postprocessed results underscored the significance of the TSD data and their potential for the structural evaluation of underlying layers in a multilayered pavement system when integrated with the site-specific pavement profile and truck traffic information derived from field testing. A comparison of the normalized deflections and structural parameters characterized by TSD and FWD data showed similar trends, while the average FWD-based deflections were 12%–37% higher than the TSD-based deflections.

Development of Pavement Performance and Remaining Service Life Prediction Tools for Iowa Jointed Plain Concrete Pavement Systems

Moving Ahead for Progress in the Twenty-First Century (MAP-21) requires US state highway agencies (SHA) to utilize performance-based approaches in their pavement management decision-making processes, and use of a remaining service life (RSL) model would be one of such performance-based approaches for facilitating the pavement management decision-making process for SHAs. In this study, statistical and artificial neural network (ANN)-based pavement performance and RSL models were developed for Iowa jointed plain concrete pavement systems (JPCP) using actual pavement structural, traffic, construction history, and pavement performance records obtained from the Iowa Department of Transportation pavement-management information system database. While both models were found to be potentially useful for project and network level performance and RSL predictions, statistical and ANN-based models were respectively found to be more suitable for project and network level analysis. Using these models, efficient Microsoft Excel-based automation tools were created to predict future performance of a JPCP section and estimate RSL values based on predicted future performance and threshold limits for the performance indicators. Consequence analysis was also conducted to investigate the impact of traffic and preservation treatment (diamond grinding) on the RSL of a JPCP. The tool, also capable of estimating realistic pavement pretreatment and posttreatment performance and RSL, could be successfully used as part of performance-based pavement management strategies and helping decision-makers make better-informed pavement management decisions to properly allocate agency resource expenditures. Moreover, this study provides a better understanding of RSL and the factors that influence both the project and network level RSL.

The Asphalt Rutting Within a Highway Tunnel A Case Study

Asphalt rutting is a major permanent degradation issue caused by the high temperature and the cyclic load of vehicles along roadways. In this work, a highway slow lane within a tunnel was affected by a relevant deformation in a relatively short time. The investigation focused on a 200 m road distance. Benkelman deflection tests on the road surface, measurements of the depth of the road deformation, particle-size distribution of the road base, Proctor and CBR tests were performed. The unbinded underground material matched the required limits. Moreover, a concrete basement with a thickness up to 60 cm was present between the upper bituminous layers and the unbinded sub-base. The concrete increased the stiffness of the whole pavement system. The road base exhibited a good bearing capacity, while the reason for the rutting needed to be found in the middle and lower bituminous layers, in spite of the wide curvature of the permanent deformation.

Condition-based pavement management systems accounting for model uncertainty and facility heterogeneity with belief updates

Due to the tighter budget for pavement management, schedules of inspection activities should be jointly optimized with the maintenance and reconstruction (M&R) plans for pavement systems. Conducting inspections every year is unnecessary and will decrease the budget for M&R activities, while infrequent inspections may lead to suboptimal M&R planning due to the lack of accurate information. This paper presents a methodology for jointly optimizing the inspection scheduling and M&R planning for pavement systems, considering model uncertainty and facility-specific heterogeneity. The problem is defined as a Partially Observable Markov Decision Process (POMDP) model, accounting for the tradeoff between the information value and inspection costs. Moreover, a statistical learning method is used to update the prediction of pavement conditions using the collected inspection data and, eventually, improve the condition-based decisions. This “belief update” process can gradually reduce the model uncertainty as the dataset size increases. We demonstrate the proposed stochastic optimization framework through a numerical example with a system of fifty heterogenous pavement facilities under a combined budget for inspection and M&R activities. Several managerial insights and implications are discussed. For example, the optimal inspection frequencies are less sensitive to the budget; and the agency should perform fewer reconstructions and more rehabilitations when the budget is limited.

A Review of Porous Concrete Pavement: Compressive Strength and Clogging Investigation

Pervious concrete pavements (PCPs) have been widely accepted as a green infrastructure solution for urban areas. Currently, pervious concrete is commonly used in permeable pavement systems such as roadways, sidewalks, driveways, parking lots, and other light-duty flatwork applications. However, the main disadvantage of this type of pavement is that it loses permeability over time due to clogging and lower compressive strength due to the pore's structures. These critical issues are the topic of this review paper. Laboratory test results relevant to the compressive strength, clogging and maintenance are discussed in detail. This review aims to present a compilation of prominent findings of studies focused on compressive strength, clogging and maintenance of PCPs. Note that PCPs with higher compressive strength must be used on roads with high traffic volumes. Subsequently, periodic maintenance is necessary to prevent sediment clogging and maximise the life of PCPs. Based on this review paper, the area of need for future research are identified.

Geothermal Pavements: Experimental Testing, Prototype Testing, and Numerical Analysis of Recycled Demolition Wastes

Geothermal pavements have the potential to reduce the pavement surface temperature by circulating fluid in pipes within the pavement structure. This research investigated an innovative geothermal pavement system with multiple benefits, such as reducing the surface temperature and harvesting heat energy for power generation. This research aimed to provide an understanding of the mechanical properties of geothermal pavements constructed with construction and demolition (C&D) waste materials through large-scale physical testing, experimental testing, small-scale prototype testing, and numerical simulation. The mechanical properties of the geothermal pavement system were assessed under long-term traffic loading conditions using a prototype test system. The repeated load triaxial and repeated-load California bearing ratio tests were also undertaken to evaluate the effect of pipe inclusion on the permanent deformation, stiffness, and strength of the pavement base. A numerical model was subsequently developed and calibrated using the data from small-scale prototype testing. In addition, the effects of the flow rate and pipe materials on the thermal performances of the geothermal pavements were also investigated in this research. The inclusion of pipes in the pavement base layer was found to have negligible detrimental effects on the deformation behavior of RCA. The resilient moduli of recycled concrete aggregate (RCA) samples slightly decreased with the inclusion of pipes. An HDPE pipe reduced the stiffness of the RCA + HDPE mix. On the other hand, a copper pipe’s high stiffness improved the mix’s strength. The numerical simulations indicated that for the HDPE pipe, increasing the flow rate from 500 mL/min to 2000 mL/min reduced the surface temperature by approximately 1.3%, while using the copper pipe resulted in an approximately 4% further decrease in the surface temperature compared to the HDPE pipe.

Flood Mitigation Performance of Permeable Pavements in an Urbanised Catchment in Melbourne, Australia (Elizabeth Street Catchment): Case Study

Permeable pavement (PP) systems have been shown to provide onsite stormwater management as well as contaminant removal benefits. Therefore, significant research has taken place in recent years to analyse the performance of these structures in terms of the volume of stormwater harvested and the water quality improvements at small scales. However, there is limited understanding of their performance for reducing stormwater runoff volume to prevent natural disasters, such as catchment-scale flooding. With larger flooding events projected to occur more frequently as a result of urbanisation and climate change, PP systems have the potential to mitigate loss by reducing peak flows and runoff volumes. Therefore, this research investigates the performance of PP at the catchment scale under a range of design rainfall and land-use scenarios. Results indicate that the integration of permeable pavements in urban settings is effective in mitigating surface flooding in an urbanised catchment in Melbourne, Australia by reducing the peak flows by 7–16%. However, in practice, flood reduction ability can markedly decrease with time due to the clogging of pavements. Our results provide preliminary data to show that the integration of permeable pavements into the existing urban landscape can reduce the risk of flooding by providing areas for water to infiltrate if maintained properly. These results are envisioned to assist councils and stormwater managers with the option evaluation of the water-sensitive urban design systems and selecting the appropriate stormwater management measures.

Numerical simulation of heat recovery from asphalt pavement in Finnish climate conditions

A 3-dimensional mathematical model of asphalt pavement system was developed, based on the fundamental energy balance, to calculate temperatures beneath asphalt surface using hourly measured solar radiation, air temperature and wind velocity data. The modelling was conducted to predict the heat retention under the asphalt surface to seek an optimum position of pipe tubing to maximise the heat extraction considering the Nordic winter conditions for future infrastructure projects. The model results show good agreement with the experimental results conducted in a span of three months (June–Sept) notwithstanding the simplification of the model i.e. thermal properties unaffected by changing moisture content, perfect contact between different layers and homogeneous and isotropic thermal properties of materials (asphalt, sand and gravel). The findings indicated that the positioning of the heat extraction tubes under the asphalt layer will be dictated by the application. For heat extraction, pipes closer to the surface are ideal for maximal heat absorption during summer, however, in winter the outer temperature may effect properties the pipes. Parameters including pipe diameter, positioning of the pipes and flow rate were analysed. Temperature increase of up to 10°C gain was observed for piping closer to the asphalt layer and 6°C for pipes position at deeper from the asphalt layer. This model could be used in future to optimise critical variables for successful implementation of asphalt heating concepts.

Cyclic strain sweep testing-analysis to evaluate the mechanical characteristics of stabilized soils

Infrastructure such as roadways, airfield pavements, and railways are primarily subjected to cyclic loading conditions. Subgrade soils for such infrastructure systems are often stabilized to meet and improve mechanical properties with the goal of achieving acceptable performance over the life of pavement or rail system under cyclic loading. This requires understanding the behavior of stabilized soils under cyclic loading as well as monotonic compressive strength as is typically done. This paper discusses a simple and fundamentally sound test method used to investigate the behavior of stabilized soils under cyclic loading. Cylindrical specimens compacted using a Harvard miniature compaction apparatus are subjected to oscillatory torsional loading applied in the strain amplitude sweep mode. To characterize the response of the stabilized soils under cyclic loading, four parameters resulting from the testing were examined: peak shear stress amplitude, dynamic shear modulus, phase angle, and dissipated strain energy. This test method was applied to a simulant soil that was treated using three different additives and cured in two ways. The results of the analysis of the test method using the four parameters showed that the coefficient of variation was in a range of 10–20%, which infers good repeatability. A high sensitivity to the type of stabilizing agents and curing conditions was observed. The energy dissipation response during strain-sweep cyclic loading showed unique time-varying hysteresis loops when different stabilizing agents and curing conditions were used. Furthermore, the method identified two critical strain amplitudes—one indicating the onset of significant nonlinear behavior and the other representing the failure of specimens. Both strain amplitudes were distinctively different from the cases when varying the stabilization methods.

Joint optimization of resource allocation and maintenance planning for multi-facility infrastructure systems

This research considers an integrated resource allocation and maintenance planning with complex maintenance effects for infrastructure systems consisting of multiple facilities. We formulate the problem as the sum of multiple finite-horizon Markov decision processes subject to budget constraints and solve it using Lagrangian relaxation method. A two-stage method is presented to solve the Lagrangian dual problem via subgradient optimization. In Stage 1, the Lagrangian relaxation problem is decomposed into individual Markov decision process problems, which generally leads to maintenance policies violating budget constraints. A Lagrangian repair heuristic is proposed to repair the infeasible policies to high-quality feasible ones in Stage 2. A computational study is conducted to demonstrate the proposed model using a pavement system with two sections.

Development and Evaluation of Sustainable Bituminous Paver Blocks

Most road surfaces globally are constructed using bituminous materials. The construction of new roads and the maintenance of existing ones demand a huge amount of virgin natural aggregates. Depletion of resources that takes place during the construction of the road has an impact on cost and also on the environment. Hence, there is a need to reduce virgin aggregate use for bituminous pavement construction. This can be achieved by utilizing sustainable materials such as marble waste and reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA)-type road construction. This research work is focused on sustainable development goal (SDG) 12, exclusively on the target number 12.5 which describes the recycling and reuse of materials. However, no investigations were seen to be reported on the integrated utilization of sustainable materials and RAP in bituminous paver blocks. The bituminous mixes were evaluated based on strength and compared with the control mix in this study. Bituminous paver blocks were then cast using sustainable materials and tested in the laboratory to assess the performance of the blocks through a compression test, Cantabro loss test, and wheel rut test. The test results gave satisfactory values; hence, these bituminous blocks can be used for service maintenance of the pavement structures. The study indicates that using sustainable material along with RAP in blocks can provide an eco-friendly, easily maintainable pavement system which makes it a key approach to SDG 9 as well, in terms of innovative infrastructure solutions.

Pavement Structure Characteristics and Behaviour Analysis with Digital Image Correlation

Digital image correlation (DIC) is a method of point displacement measurement by an optical system. If two cameras are used for capturing the same point displacement, three-dimensional data are obtained using the 3D-DIC method. The areas of application of this method in pavement construction are diverse, but it is mainly used for displacement monitoring during standard tests of the failure of specimens due to load application. Furthermore, DIC technology was used only for testing particular material characteristics and assuming their influence on the overall pavement system. Within this research, DIC was applied in two areas: defining material mechanical characteristics and analyses of pavement structure behaviour under cyclic loading. The scope of this research was to gain more insights into DIC’s potential application within pavement behaviour analyses, specifically on cement-bound granular material (CBGM) characterisation. Results from this study confirm the suitability of 3D-DIC technology for pavement material characterisation. Furthermore, it is shown that certain trends of material behaviour defined on the simple material level of each independent pavement layer will significantly differ when it is placed in the system, and this kind of complex analysis is possible by using 3D-DIC technology.

Financial Feasibility of Harvesting Rainwater from Permeable Pavements: A Case Study in a City Square

The objective of this study was to carry out the financial feasibility analysis of harvesting rainwater from permeable pavements in a city square. A case study was carried out in a square close to the beach in the city of Florianópolis, Brazil. Questionnaires were applied to pedestrians who circulate within the area. The square is to be implemented to promote sustainability and improve the user’s quality of life. From the rainfall data and the average daily water demand for irrigation of the square vegetation, the volume of rainwater to be harvested from the permeable pavement was calculated. The rainwater demand was estimated as 662 L/day. The implementation and operation costs of the pavement and irrigation systems were evaluated. The potential for potable water savings was 89.8%. The payback period was estimated as 347 months. This study showed that rainwater collected from permeable pavements is financially feasible and represents a promising technique.

A Study on Indirect Tensile Strength for the Determination of Resilient Modulus of Warm Mix Asphalt

The advent of Warm Mix Asphalt (WMA) incorporating Recycled Asphalt Pavement (RAP) as a long-term solution to partially or totally participate in remediating the problem of global warming and the regression of environmental resources has been expanding and gaining interest throughout the world. The WMA-RAP technology created as an improved WMA technology has shown to possess mechanical properties closely similar to Hot Mix Asphalt (HMA). Though searching for environmentally sustainable asphalt technologies have become vital, the quest to construct economically sustainable highways cannot be neglected. The dynamic modulus tests (DMT) is among the most accurate yet expensive laboratory tests performed to determine the resilient modulus of asphalt mixes. Therefore, this paper aims to determine the resilient modulus of asphalt mixes (WMA-RAP and HMA) through both the indirect tensile strength (ITS) and the correlation formula method (CFM) and compares them against the dynamic modulus tests method (DMTM). Furthermore, this study utilises the resilient modulus found through CFM and DMTM to predict and compare the mechanical performances of asphalt pavement systems. Finite Element Modelling (FEM) and Linear Elastic Analysis (LEA) were used to modelling and analysing the mechanical behaviour of pavement systems. Both the WMA15% RAP and WMA30% RAP samples were mixed with 50/70 grade bitumen modified with Sasobit additive. The HMA samples on the other hand were mixed with non-modified 50/70 grade bitumen. Findings show that the resilient moduli of HMA and WMA-RAP mixes obtained through CFM is 77% close to the DMTM. In addition, the HMA and the WMA-RAP pavements with CFM and DMTM resilient moduli also show very close mechanical performance. This signifies that the CFM can be used as a reliable and cost effective alternative method to determine the resilient modulus of asphalt mixes.