Portland Cement Concrete Layer Research Articles

Study of Damping of Bare and Encased Steel I-Beams Using the Thermoelastic Model

Steel I-beams are a fundamental structural component in civil construction. They are one of the main load-bearing components in a building that must withstand both the structure and any incoming external perturbations, such as seismic events. To avoid damage to the structure, the building must be designed to dissipate the maximum amount of energy possible. One way energy can be dissipated is through internal or structural damping, of which thermoelasticity is one of the causes, especially in low-frequency harmonic excitations. The main goal of this study is to analyze the amount of damping in an I-beam generated by thermoelasticity and when encased in a Portland cement concrete layer, using a Finite Element model. It was found that, due to the geometry of the I-Beam, the damping coefficient as a function of frequency has two local maxima, as opposed to the traditional single maximum in rectangular beams. Encasing an I-beam in a concrete layer decreases the overall damping. While the extra coating protects the beam, the reduction in damping leads to a lower energy dissipation rate and higher vibration amplitudes.

Mechanistic Responses of Asphalt Concrete Overlay Over Jointed Plain Concrete Pavement Using Finite Element Method

This study focused on the development of a three-dimensional Finite Element Model of an asphalt concrete overlaid on a jointed plain concrete pavement to assess the mechanical behaviour of the pavement under traffic load. The objective of this study was to determine the influence of different asphalt concrete thickness, asphalt concrete modulus, the interface bond between the asphalt concrete and the Portland cement concrete layer, Portland cement concrete modulus, and joint width on the tensile strain at the bottom of the asphalt overlay. The results showed that changes in the pavement parameters result in a large range of variations on the magnitude of pavement responses. The magnitude of the longitudinal tensile strain at the bottom of the overlay varied between 25 με and 460 με. Asphalt concrete thickness, interface contact condition, and asphalt concrete modulus parameters had the most influence on the pavement responses. The interface bonding condition was significant, regardless of the thickness of the surface layer.

Structural Characterization of Fractured Portland Cement Concrete Pavements in Pennsylvania from Falling Weight Deflectometer Data

Hot mix asphalt (HMA) overlays on fractured Portland cement concrete (PCC) is a common rehabilitation alternative used for PCC pavements in Pennsylvania. Several fracture techniques including rubblization, crack and seat (C&S), and break and seat (B&S) have been used for decades to minimize reflective cracking by reducing the effective slab length and, with it, expansion/contraction movement. The design of this type of overlay requires knowledge of the structural capacity of the fractured PCC layer. The AASHTO 93 and Pavement ME design methods are used by the Pennsylvania Department of Transportation (DOT). These methods and the Pennsylvania DOT documentation recommend certain values to characterize the structural capacity of the fractured PCC. However, the guidance envisaged the selection of these values provided by these design methods and the Pennsylvania DOT documentation is limited. The objective of this study is to determine realistic Pennsylvania-specific elastic modulus (EPCC) values and layer coefficients (LC) to characterize the in situ behavior of fractured PCC layer for jointed reinforced concrete pavements (JRCP) and jointed plain concrete pavements (JPCP). To obtain these structural properties, 11 different rehabilitation projects located in Pennsylvania were analyzed using falling weight deflectometer (FWD) data, backcalculation programs, and statistical methods. Based on this analysis, the recommended values of EPCC and LC for C&S overlay design are 360 ksi (kips per square inch) and 0.32, respectively. In the case of B&S overlay design, these values correspond to 400 ksi and 0.34, respectively. The variability of the slab fracturing process and the reduction of the structural capacity caused by fracturing were also analyzed in this investigation.

Development of rapid three-dimensional finite-element based rigid airfield pavement foundation response and moduli prediction models

Abstract Designing pavement foundation for rigid airfield pavements and understanding the contribution of pavement foundation elements to overall pavement performance and pavement failure have been challenges for the rigid airfield pavement design community. While many models have been developed to best simulate pavement foundation behavior for rigid airfield pavements, many of them have focused only on the failure of Portland Cement Concrete (PCC) layer and did not sufficiently consider the contribution of pavement foundation to the failure. The Federal Aviation Administration’s (FAA’s) pavement design software, FAARFIELD, considers the maximum horizontal stress at the bottom edge of the concrete slab for bottom-up cracking failure of a PCC layer, but does not consider the critical responses for failure of subbase and subgrade layers in rigid pavement design. It is clear that incorporating critical pavement foundation responses into pavement design procedures is of great interest. The primary objective of this paper is to investigate the feasibility of developing rapid three-dimensional finite-element (3D-FE)-based pavement foundation response and moduli prediction models for design of both new and rehabilitated rigid airfield pavement structures. The three case studies investigated in the development of the models include: (1) rigid pavement foundation response prediction models for different wide body aircraft loading conditions, (2) rigid pavement foundation response prediction models for Heavy/Falling Weight Deflectometer (H/FWD) loading conditions, and (3) single rigid-pavement moduli prediction model. The development procedure and results based on rapid 3D-FE based prediction models are presented in this paper along with other significant findings and recommendations for employing the developed models in the structural design and evaluation of rigid airfield pavement systems. It was found that the developed models were able to successfully predict 3D-FE pavement solutions for all cases investigated in this study, could account for rigid pavement foundation related distresses, and could be potentially integrated into FAARFIELD as surrogate forward response prediction models in the future.

Glass fiber reinforced asphalt membrane for interlayer bonding between asphalt overlay and concrete pavement

The aim of this study is to evaluate the shear and fatigue behavior of asphalt concrete (AC) overlay on Portland cement concrete (PCC) pavement with different interlayer bonding materials, including modified emulsified asphalt (MEA) membranes, modified asphalt (MA) membranes, glass fiber reinforced modified emulsified asphalt (GFMEA) membranes and glass fiber reinforced modified asphalt (GFMA) membranes. An in-house shearing device was used to evaluate the shear behavior between asphalt layer and PCC layer. An orthogonal experimental design was performed to determine the impact of each influential factor on the interlayer shear behavior, including the testing temperature, the bonding material, and the confinement pressure applied during the tests. The results indicate that AC overlay on PCC pavement can reach its optimal performance in terms of shear toughness when the GFMA is used at the interlayer. Four-point bending fatigue tests were conducted on the AC beam with interlayers using the Material Test System (MTS). The fractal dimension (FD) of fatigue cracks in AC overlay was analyzed using image measurements. The results show that the AC beam with the GFMA has a longer fatigue life. Therefore, it is concluded that the GFMA can strengthen bonding and mitigate reflection cracking of AC overlay on PCC pavements.

Modification of Mechanistic–Empirical Pavement Design Guide Procedure for Two-Lift Composite Concrete Pavements

Modifications made to the Mechanistic–Empirical Pavement Design Guide (MEPDG) to accommodate the design of a newly constructed composite pavement system featuring a thin portland cement concrete (PCC) layer placed over another PCC layer (PCC–PCC pavement) are described. In previous versions of the MEPDG, a newly constructed PCC–PCC pavement project was considered a bonded PCC overlay of an existing PCC pavement. As a result of this simplification, the MEPDG was not consistent in its predictions for a newly constructed PCC–PCC pavement and its structurally equivalent single-layer analogue. To remedy this inconsistency, researchers suggested modifications to the Enhanced Integrated Climatic Model (EICM) used by the MEPDG in terms of (a) number of locations through the slab used by EICM to determine the thermal gradient and (b) EICM calculation of the subgrade spring stiffness (or k-value). Before-and-after MEPDG sensitivity analyses are included to justify the modifications developed and implemented into the MEPDG with the assistance of the MEPDG development team. This research was conducted under SHRP 2 R21, Composite Pavement Systems.

Determination of Critical Bending Stresses in Portland Cement Concrete Layer with Asphalt Overlay

An asphalt concrete overlay of a jointed plain concrete pavement is intended to extend the service life of the existing pavement structure. Also known as composite pavements, these structures exhibit features of both rigid and flexible pavements. Whereas the behavior of rigid pavements is mainly elastic, the behavior of an asphalt layer is dependent on load duration. At the same time, temperature curling causes nonlinear interaction with the foundation. The available structural models for composite pavements ignore the behavior of the asphalt layer that is load duration dependent when the composite pavement is subjected to a combination of temperature curling and traffic loads. Research was conducted to address the improvement of structural modeling of composite pavements that were subjected to slow-developing temperature curling and instantaneous traffic loads. A simplified procedure was developed that maintained compatibility with the Mechanistic–Empirical Pavement Design Guide. The procedure used a different asphalt modulus for curling than it did for axle loading and determined the total stresses in the pavement as a combination of the stresses from solutions of three elastic boundary value problems. The simplified procedure was compared with the existing design guide structural model for fatigue cracking in a jointed plain concrete pavement overlain with asphalt concrete. A framework for implementing the proposed procedure into the design guide was developed.

Structural Characterization of Iowa’s Rubblized PCC Pavements

AbstractRubblization is considered one of the sustainable surface preparation techniques before placing a hot mix asphalt (HMA) overlay that involves breaking the concrete pavement into pieces. The design of the structural overlay thickness for rubblized projects is difficult as the resulting structure is neither a true rigid pavement nor a true flexible pavement. The most important aspect of the design procedure is to characterize the rubblized concrete layer in terms of a layer coefficient and modulus for the empirical and the mechanistic-empirical (M-E) pavement design methods. This paper describes a field study undertaken to investigate the performance of rubblized pavements in Iowa, which includes characterization of the rubblized Portland cement concrete (PCC) layer (layer coefficient and modulus) using a neural networks-based layer moduli backcalculation program. The average rubblized PCC layer coefficient and backcalculated modulus of the rubblized layer in Iowa were found to be 0.19 and 539 MPa (...

NON-DESTRUCTIVE EVALUATION OF IN‐PLACE REHABILITATED CONCRETE PAVEMENTS

Several in‐place rehabilitation techniques have been used before placing an Asphalt Concrete (AC) overlay on Portland Cement Concrete (PCC) pavements in attempts to minimize reflection cracking. Among these techniques, “rubblization” of PCC has been recognized to be the most utilized procedure for the mitigation of reflection cracking in US. This paper presents the practices on the use of rubblization in US and discusses the performance of this technique based on field evaluation. The specifications for the rubblization procedure used by state Department of Transportation (DOT) in US were reviewed. To evaluate the performance of rubblization technique, the structural and the surface conditions of AC overlaid pavements with rubblized PCC layer are compared to those with virgin PCC layer. A series of field experiment tests were carried out on six representative AC overlaid pavements with both rubblized PCC and virgin PCC in Iowa during 2007. The field experiment tests include the Nondestructive (NDT) and destructive tests, and the distress survey. Deflection Basin Parameters (DBPs) were derived from NDT test results to characterize the structural condition of pavements. The results indicate that the rubblized PCC layer has strength comparable to that of virgin PCC layer and has better performance under that structural condition. Santrauka Siekiant nustatyti asfaltbetonio (AC) sluoksnio veiksminguma, mažinant plyšiu ir itrūkiu atsiradima portlandcemenčio betono (NKK) dangose, buvo taikyti keli kelio dangu rekonstrukcijos metodai. Vertinant ivairius plyšiu susidaryma mažinančius keliu rekonstrukcijos metodus, geriausiu buvo pripažintas regeneracijos metodas (PCC rubblization), taikomas JAV. Nagrinejama mineto regeneracijos metodo taikymo patirtis JAV ir analizuojamos jo taikymo galimybes bei veiksmingumas. Ši keliu atnaujinimo metoda taiko JAV Transporto departamentas (DOT). Siekiant ivertinti nagrinejamo regeneracijos metodo veiksminguma eksploatacinemis salygomis, AC buvo padengtas pagal naujaji metoda paruoštu PCC sluoksniu, ir gauti tyrimu rezultatai palyginti su standartiškai paruošto PCC sluoksnio rezultatais. Natūriniai eksperimentiniai bandymai buvo atlikti, taikant neardomuosius (NDT) ir ardomuosius tyrimu metodus. Ilinkiai (DBPs) buvo nustatyti NDT bandymo metodais, charakterizuojančiais konstrukcines dangu salygas. Darbo rezultatai parode, kad pagal naujaji metoda paruoštas PPC sluoksnis igijo panašu stipri kaip ir PCC sluoksnis su standartine danga, tačiau regeneruota PPC danga igijo geresniu eksploataciniu charakteristiku.

Comprehensive Evaluation of Effect of Climate in Mechanistic–Empirical Pavement Design GuidePredictions

Climatic and environmental conditions have significant effects on pavement performance but have been inadequately considered in previous design methods. The Mechanistic–Empirical Pavement Design Guide (MEPDG) accounts for these effects through the use of the enhanced integrated climatic model. The present study examined the effects of climate on pavement performance predictions and the effects of climatic file generation by using MEPDG. The paper details the effort required to compare performance predictions for composite pavement consisting of asphalt cement over portland cement concrete (PCC) for 610 locations across the United States, with the use of MEPDG, Version 1.0. Analysis of the results was performed at the national, regional, and local levels. Although in general the results agree with the anticipated trends of environmental effects on pavement performance, the prediction of performance according to the predicted transverse cracking in the PCC layer was found to contain inconsistencies. These inconsistencies are attributed to the quality of the climatic data. The paper concludes that the MEPDG climatic database should be cleansed of incomplete or questionable climatic data files to ensure reliable performance prediction.

PCC Airfield Pavement Response during Thaw-Weakening Periods

A field study was performed at two regional airports in Wisconsin during spring thaw to determine its effects on portland cement concrete (PCC) airport pavements. This study was part of a research program to model the performance of airfield pavements for the Federal Aviation Administration. Subsurface temperature and falling weight deflection measurements of the pavement structures were taken at both airports and used to calculate the frost penetration depths, the changes in bearing capacity, and the joint and load transfer efficiencies. This paper summarizes the findings of this study and includes several relationships between various engineering properties of the subsurface layers below the PCC layer, along with a procedure for evaluating pavement performance using falling weight deflection data for PCC pavements during spring thaw.