Search

This paper focuses on successful application of permeable pavement design and performance with special emphasis on stormwater management, water quality benefits, and identification of knowledge and data gaps. The paper provides a summary of the current practice and design methods, discusses the potential application of permeable pavement for highway environment, summarizes the research progress documented in the literature related to mixed design, hydrologic performance, maintenance, water quality benefits, identifies knowledge gaps and unresolved issues, and explores the future direction in permeable pavement application. While there are many successful permeable pavement installations in parking lots and commercial areas with low speed and light traffic loads, only a handful of demonstration projects and simulation studies have evaluated the use of permeable pavements for highways and urban roads with higher vehicle speeds and heavier loads. Those studies and simulations have shown promising results.View the NCST Project Webpage

Under current provision of the Clean Water Act (CWA) and the amended National Pollution Discharge Elimination System (NPDES) all communities with populations of 10,000 or more, which includes nearly all jurisdictions in the United States, are required to regulate and control the discharge of urban stormwater into receiving water bodies. The CWA and related regulatory compliances and societal demands for clean water have exerted a tremendous amount of pressure on stormwater runoff dischargers throughout the United States to develop innovative stormwater treatment and management strategies.A more environmentally beneficial and cost-effective approach to capturing, treating, and slowing down water runoff generated by road surfaces is the use of a full depth permeable pavement shoulder design. Under this proposed design, most if not all runoff will be retained within the shoulder and there would not be a need for additional treatment. The use of permeable pavement shoulders in highly urbanized areas is particularly beneficial since finding sufficient land area to implement other solutions (such as infiltration or detention basins) is difficult.This policy brief summarizes findings from the research project on successful application of permeable pavement design and performance with special emphasis on stormwater management, water quality benefits, and identification of knowledge and data gaps. View the NCST Project Webpage

Concrete pavements develop cracks with the accumulation of fatigue damage caused by the combined effect of vehicular and environmental loadings. In Mechanistic-Empirical (ME) design, the ratio of stresses to some measure of strength is used to evaluate incremental damage, which is then related to cracking. Typically, this measure is the Modulus of Rupture (MOR) of a beam made of the same material. The flexural strength is also known to vary with the thickness of the beam. However, the variation of flexural strength due the presence of eigenstresses from temperature or moisture distributions has not received sufficient attention. A non-linear fracture mechanics model demonstrated that the thickness-adjusted flexural strength can also be used for characterising the maximum elastic stress under a linear temperature distribution. However, under a non-linear temperature distribution, the material may sustain a higher or lower maximum elastic stress than the flexural strength. To model this, a practical analytical expression for the apparent flexural strength was derived and showed excellent agreement with numerical simulations as well as with a model based on equivalent elastic deformation energy. The model was used to show that the fatigue capacity under a typical axle load varies with various non-linear temperature distributions. [ABSTRACT FROM AUTHOR]

Moisture excess in granular pavement layers can decrease pavement performance leading to moisture-related distresses. The combination of trapped water and heavy traffic loads may substantially increase pore pressure and lead to shear failure if layer hydraulic conductivity is insufficient. Currently, most pavement analysis models are unable to predict pore pressure development, so the design and evaluation methods ignore this dynamic effect which may significantly underestimate the moisture damaging effect on pavements. This paper proposes the use of Biot's poroelasticity theory for modelling fully saturated unbound materials. The proposed methodology – Poroelastodynamic Finite Integration Technique (PEFIT) – was used to analyze axisymmetric multilayered pavement structures consisting of elastic and poroelastic layers. The model was verified and validated using a well-known commercial finite element solver and field pore pressure data, respectively. A sensitivity analysis was conducted by varying critical pavement design parameters. The PEFIT analysis of a three-layer pavement system with a poroelastic base layer has shown that a decrease in base hydraulic conductivity significantly increases the maximum pore pressure, especially for high-speed loads. Results also indicate substantial pore pressure and water movement in the base layer, which may induce a potential shear failure mechanism for unbound materials. [ABSTRACT FROM AUTHOR]

During concrete pavement construction, comprehensive information on concrete strength development is necessary for knowledgeable scheduling decisions. To improve in situ strength estimation, nondestructive tests can be combined to maximize available information and increase collection efficiency. Ultrasonic testing has a higher accuracy in strength estimation for early age concrete and the external device allows for more data to be easily collected, while maturity testing can use temperature models to predict strength development. A procedure was created that combines these methods and their strength models in the laboratory for improved and increased field strength data. Using the procedure allows more data to be collected with greater accuracy and provides an adjustable, predicted strength development. This improves the efficiency of fast-track construction projects without resorting to costly alternatives by providing more information on strength development of in situ concrete than traditional strength testing or nondestructive methods individually. [ABSTRACT FROM AUTHOR]

Continuously reinforced concrete pavement (CRCP) is a widely used alternative for heavy traffic highways due to good performance and low maintenance needs. Recently, the use of short length CRCP (50-m long slabs) has been proposed for bus stops and terminals. This paper examines the structural behaviour of cracks in short CRCP. This includes analysis of the Falling Weight Deflectometer (FWD) deflections and strain gauge measurements obtained from the full-scale test sections as well as structural modelling of the pavement. An evaluation of the influence of cracks on the FWD deflection basins collected on the experimental short CRCP pavement along with FWD data collected under the Long-Term Pavement Performance programme for conventional CRCP resulted in similar behaviour between the short and conventional CRCP. Therefore, the effects of the short CRCP transverse cracks on stresses were investigated. Three ISLAB2000 models differed by the concrete base or crack model were developed and their stress predictions were compared with field stresses. An applicability of the conventional aggregate interlock model for describing the behaviour of short CRCP was evaluated as only the continuous slab (no cracks) model was able to match the field stresses. A need for re-appraisal of the PavementME structural model is also discussed. [ABSTRACT FROM AUTHOR]