Browsing by Subject "Composite pavements"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    A coupled lattice and nite element model for fracture in composite concrete pavements
    (2012-11) Tompkins, Derek Michael
    Recent research in the United States has focused on the design, construction, and performance of composite concrete pavements - i.e., two heterogeneous concrete layers placed soon after the other using "wet-on-wet" techniques. While these pavements offer many benefits, they also introduce some uncertainties, including the possibility of thermally, hygrally, or mechanically induced fracture and separation at interface of the concrete layers. Despite over 40 years of experience in Europe that has yet to observe debonding in composite concrete pavements, debonding remains a commonly held concern among pavement engineers in the United States. To complement field evidence from Europe in addressing debonding concerns, this dissertation describes the development of a computational tool specifically designed for the simulation of a composite pavement under thermal, hygral, and mechanical loads. This simulation would be difficult using an exclusively continuum approach such as finite element methods in view of the heterogeneity of the pavement materials and the associated lack of smoothness in the crack propagation path. Given that the problem involves both heterogeneous media and the interface between the pavement layers, in this thesis the simulations are instead conducted using three-dimensional lattice modeling with emphasis on the potential for mixed-mode fracture at the interface. This discrete approach is coupled with a finite element model for plate behavior away from the potential cracking zone. The intricacies of that coupling are discussed and illustrated through numerical tests and examples.
  • Thumbnail Image
    Item
    Cracking of the PCC layer in composite pavement.
    (2011-12) Saxena, Priyam
    An asphalt concrete (AC) overlay of a jointed plain concrete pavement (JPCP) is intended to extend the service life of the existing pavement structure. Also known as composite pavements, such pavements exhibit features of both rigid and flexible pavements. While behavior of rigid pavements is mainly elastic, behavior of asphalt layer is load-duration dependent. At the same time, temperature curling causes non-linear interaction with the foundation. The available models of composite pavement ignore the behavior of the load duration dependent asphalt layer when the composite pavement is subjected to a combination of temperature curling and traffic loads. This research concentrates on the improvement of structural modeling of composite pavements subjected to slow developing temperature curling and instantaneous traffic loads. A finite element (FE)-based model accounting for the viscoelastic behavior of the asphalt layer in composite pavements is developed and verified using comparisons with semi-analytical solutions obtained in this study. In order to maintain compatibility with the Mechanistic-Empirical Pavement Design Guide (MEPDG) framework, a simplified procedure is developed. The procedure uses a different asphalt modulus for curling than for axle loading and determines the total stresses in the pavement as a combination of the stresses from solutions of three elastic boundary value problems. The simplified procedure is compared with the existing MEPDG model for fatigue cracking in AC overlaid JPCP. A framework for the implementation of the proposed model into the MEPDG is also developed.
  • Thumbnail Image
    Item
    Design and Construction Guidelines for Thermally Insulated Concrete Pavements
    (Minnesota Department of Transportation, 2013-01) Khazanovich, Lev; Balbo, Jose T.; Johanneck, Luke; Lederle, Rita; Marasteanu, Mihai; Saxena, Priyam; Tompkins, Derek; Vancura, Mary; Watson, Mark; Harvey, John; Santero, Nicholas J.; Signore, James
    The report describes the construction and design of composite pavements as a viable design strategy to use an asphalt concrete (AC) wearing course as the insulating material and a Portland cement concrete (PCC) structural layer as the load-carrying material. These pavements are intended for areas with heavy trucks and problem soils to increase the service life and minimize maintenance. The project focused specifically on thermally insulated concrete pavements (TICPs) (that is, composite thin AC overlays of new or structurally sound existing PCC pavements) and developed design and construction guidelines for TICPs. Specific research objectives include determining behavior of the layers of the TICP system, understanding life-cycle costs and the feasibility of TICPs, and incorporating the results into design and construction guidelines. Both construction and design guidelines are considered in light of the construction and performance of TICP test sections at the Minnesota Road Research project (MnROAD).
  • Thumbnail Image
    Item
    Intelligent Pavement for Traffic Flow Detection – Phase I
    (Intelligent Transportation Systems Institute, Center for Transportation Studies, University of Minnesota, 2012-09) Yu, Xun
    This project explored a new approach in detecting vehicles on a roadway by making a roadway section itself a traffic flow detector. Sections of a given roadway are paved with carbon-nanotube (CNT)/cement composites; the piezoresitive property of carbon nanotubes enables the composite to detect the traffic flow. Meanwhile, CNTs can also work as the reinforcement elements to improve the strength and toughness of the concrete pavement. In contrast to current traffic flow detection technologies that require separate devices to be installed either in the pavement or over the road, the proposed sensing approach enables the pavement itself to detect traffic flow parameters. Therefore, the proposed sensor is expected to have a long service life with little maintenance and wide-area detection capability.
  • Thumbnail Image
    Item
    Intelligent Pavement for Traffic Flow Detection – Phase II
    (Intelligent Transportation Systems Institute, Center for Transportation Studies, University of Minnesota, 2012-09) Yu, Xun
    This project is the extension of a Northland Advanced Transportation System Research Laboratory (NATSRL) FY09 project, titled as “Intelligent Pavement for Traffic Flow Detection”, which aims to explore a new approach in detecting vehicles on a roadway by making a roadway section as a traffic flow detector. Sections of a given roadway are paved with carbon-nanotube (CNT) enhanced pavement; the piezoresitive property of carbon nanotubes enables the pavement to detect the traffic flow. Meanwhile, CNTs can also work as reinforcement elements to improve the strength and toughness of the concrete pavement. The proposed sensor is expected to have a long service life with little maintenance and wide-area detection capability. In the FY09 project, lab tests demonstrated that CNT based cement composite can detect the mechanical stress levels for both static and dynamic loads. In the FY10 project, the research was extended to cement mortar, which has much higher mechanical strength and more useful in real applications. The effects of water level and CNT doping levels on the piezoresistivity of the composites were also studied. Preliminary road tests were performed for the evaluation of this new traffic sensor.