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Buch N.,Michigan State University | Jahangirnejad S.,Quality Engineering Solutions Inc.
International Conference on Concrete Pavement Design, Construction and Rehabilitation | Year: 2011

The coefficient of thermal expansion (CTE) is defined as the change in unit length per unit change in temperature. It is usually expressed in microstrain (10 -6) per degree Celsius (μ&EPSI/°C) or microstrain (10 -6) per degree Fahrenheit (μ&EPSI/°F). The CTE of Portland Cement Concrete (PCC) is an Important parameter In analyzing thermally induced stresses in jointed concrete pavements (JCPs) during the first 72-hours after paving and over the pavement design life. The magnitude of CTE is also important in determining the amount of joint movement, slab length, and joint sealant reservoir design. The Mechanistic-Empirical Pavement Design Guide (M-E PDG) allows for the input of CTE at three levels (quality of data); (i) Level 1 of CTE determination involves direct measurement in accordance with a test protocol developed by American Association of State Highway and Transportation Officials (AASHTO) titled AASHTO TP60, "Standard Test Method for CTE of Hydraulic Cement Concrete" (Now, AASHTO T336-10, Standard Method of Test for Coefficient of Thermal Expansion of Hydraulic Cement Concrete); (ii) Level II of CTE determination uses a weighted average of the constituent values based on the relative volumes of the constituents; and (iii) Level III of CTE estimation is based on historical data. This paper quantifies the impact of test variables such as aggregate geology, sample age and the number of heating and cooling cycles on the magnitude of CTE. Furthermore, the paper summarizes the Impact of these CTE test variables on the predicted performance (e.g. transverse cracking) of jointed concrete pavements using M-E PDG models.


Wang G.,Quality Engineering Solutions Inc. | Roque R.,University of Florida
Road Materials and Pavement Design | Year: 2011

The effects of truck tire types on near-surface pavement responses were evaluated via finite element anyalysis. First, two wide-based truck radial tires (425/65R22.5 and 445/50R22.5) were modeled based on the tire geometries and specifications from the tire manufactures. Accordingly, tire-pavement interaction models were developed. These models were then calibrated to make sure models can be used for further evaluation purpose. A study on how truck tire types affect near-surface respones were investigated based on calibrated tire-pavement contact models. The results indicated that the Super Single (SS) (425/65R22.5) tire produced the worst damage to the pavement in terms of top-down cracking and AC rutting in Asphalt Concrete (AC) layers, while New Generation Wide-Based (NGWB) tire (445/50R22.50) induced approximately the same damage as the standard dual tire assembly (11R22.5) evaluated in this study. © 2011 Lavoisier, Paris.


Wang G.,Quality Engineering Solutions Inc. | Roque R.,University of Florida
International Journal of Pavement Research and Technology | Year: 2011

The effects of truck tire types on near-surface pavement responses were evaluated via finite element anyalysis. First, three truck radial tires (11R22.5, 425/65R22.5, and 445/50R22.5) were modeled based on the tire geometries and specifications from the tire manufactures. Accordingly, tire-pavement interaction models were developed. These models were then verified by comparing predicted contact stresses with measured ones to make sure models can be used for further evaluation purpose. The results indicated that the super single (425/65R22.5) tire produced greater contact stress and more damage to the pavement in terms of top-down cracking and instability rutting, while new generation wide-based tire (445/50R22.50) induced approximately the same damage as the standard dual assembly tested (11R22.5). © Chinese Society of Pavement Engineering.


Wang G.,Quality Engineering Solutions Inc. | Roque R.,University of Florida | Morian D.,Quality Engineering Solutions Inc.
Transportation Research Record | Year: 2011

A sophisticated three-dimensional (3-D) tire model was placed directly on a three-layer asphalt concrete (AC) pavement system to form a 3-D tire-pavement contact model. The model was then verified with measured contact stresses and was used to investigate near-surface stress states in the AC layer. When compared with the traditional uniform vertical loading model, the 3-D tire-pavement contact model produced stress states not only higher in magnitude but also more variable in distribution. The 3-D tire-pavement contact model produced much higher principal tensile stress and maximum shear stress near the tire edge; the increased stress was a possible explanation for instability rutting and associated top-down cracking. A critical shear plane was developed for the top 50 mm of the AC layer by using a p-q diagram, and the tire-pavement contact model produced a much higher shear yield percentage.


Wang G.,Quality Engineering Solutions Inc. | Roque R.,University of Florida | Dennis Morian P.E.,Quality Engineering Solutions Inc.
Journal of Materials in Civil Engineering | Year: 2012

Road surface profile is an important factor that affects the dynamic responses of the vehicle, which in turn affects pavement responses. In this study, a complete two-dimensional (2D) axle-tire-pavement interaction finite-element model was developed to investigate the effects of a rutted surface on near-surface pavement responses. The results indicate there is a significant difference in tire-pavement contact stress distributions between a rutted surface and a flat surface. The presence of a rutted surface increases both the propensity for top-down cracking and the severity of instability rutting. The observed trend indicates that the greater the existing rut severity is, the more likely it is for top-down cracking and increased rutting to occur. © 2012 American Society of Civil Engineers.

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