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Van Buren, KS, United States

Gedafa D.,University of Connecticut | Hossain M.,Kansas State University | Romanoschi S.,University of Texas at Arlington | Gisi A.,Materials and Research Center
Transportation Research Record | Year: 2010

Currently, hot-mix asphalt (HMA) mixture design and pavement structural design are not fully integrated, although Superpave® asphalt mixture design is somewhat project specific. The objective of this study was to compare elastic moduli assumed during structural design of pavements with the backcalculated moduli of HMA layers obtained from the falling weight deflectometer (FWD) tests and the dynamic modulus values measured in the laboratory. Five newly built Superpave pavements, designed by using the 1993 AASHTO Design Guide, were selected as study sites in this research. Deflection data were collected with a Dynatest 8000 FWD on a 1,000-ft test section at each site. The HMA layer moduli were then backcalculated by using an elastic-layer analysis program. Full depth cores were taken from each section and tested in the laboratory for dynamic moduli. The results showed that backcalculated and laboratory moduli were somewhat comparable for all practical purposes. The laboratory dynamic moduli increased with the loading frequency, indicating the need for consideration of vehicle speeds in the HMA pavement structural design. HMA design moduli, assumed by the Kansas Department of Transportation during pavement structural design, are lower than both backcalculated and laboratory dynamic moduli. Thus, current HMA design moduli are achievable in the field through Superpave mixture design, despite the fact that the pavement structural design and mix design processes are not integrated.

Gedafa D.S.,University of North Dakota | Hossain M.,Kansas State University | Romanoschi S.A.,University of Texas at Arlington | Gisi A.J.,Materials and Research Center
Airfield and Highway Pavement 2013: Sustainable and Efficient Pavements - Proceedings of the 2013 Airfield and Highway Pavement Conference | Year: 2013

In the Mechanistic-Empirical Pavement Design Guide (MEPDG), prediction of flexible pavement response and performance needs an input of dynamic modulus of hot-mix asphalt (HMA) at all three levels of hierarchical inputs. This study investigated the effect of aging on the dynamic modulus and fatigue life of Superpave mixes. Five newly built Superpave pavements for local calibration of MEPDG by the Kansas Department of Transportation (KDOT) were selected as test sections in this study. Volumetric properties of the mixes have been obtained from the mix design database of KDOT. Asphalt concrete (AC) cores were obtained at 30.5-m intervals over a 305-m section from all calibration sites and tested in the laboratory for dynamic moduli. Dynamic modulus was predicted with the Witczak equation. The results show that there is an increase in predicted modulus with an increase in age and frequency of loading. The difference between predicted modulus initially and after five years is greater than the difference between the predicted moduli after five and 10 years. This shows that the aging process slows down with time. The rate of increase in predicted modulus over the years is higher at 21 C than at 35 C. Increase in dynamic modulus with aging results in decrease in tensile strain, but the rate of increase in the predicted number of load repetitions is greater than the allowable number of load repetitions. As a result, fatigue life decreases with time. Laboratory dynamic modulus was comparable for all U.S. routes at 4 C. The variation increased as the test temperature increased. Witczak equation underestimated the dynamic modulus at low temperature and overestimated at high temperature when compared with the laboratory modulus. © 2013 American Society of Civil Engineers.

Gedafa D.S.,University of Connecticut | Hossain M.,Kansas State University | Miller R.,Materials and Research Center | Steele D.A.,Applied Research Associates Inc.
Journal of Testing and Evaluation | Year: 2010

Structural evaluation can be very useful at the network level of pavement management for project prioritization purposes. However, due to expenses involved in data collection and analysis, pavements are not tested for structural capacity at the network level. Rolling wheel deflectometer (RWD), which measures surface deflections at highway speed, is an alternate, faster method of pavement deflection testing for network level data collection. This study was initiated to assess the feasibility of using RWD for network level pavement deflection measurements. RWD deflection data was collected under an 80-kN axle load and at about highway speed on non-interstate highways in northeast Kansas in July 2006. Falling-wheel deflectometer (FWD) data on these roads, collected from 1998 to 2006, were also used for comparison. The computed effective structural numbers from both FWD and RWD deflection data were compared. The results show that the deflections measured by RWD and the center (first sensor) deflections from FWD are statistically similar. The effective structural numbers computed from the FWD and RWD deflection measurements are also statistically similar. Thus RWD appears to be a valuable tool for structural capacity evaluation of pavements at the network level. © 2010 by ASTM International.

Rahman F.,Kansas State University | Hossain M.,Kansas State University | Romanoschi S.A.,University of Texas at Arlington | Brennan J.,Materials and Research Center
Geotechnical Special Publication | Year: 2012

Compaction of highway embankment is a key factor influencing premature pavement distresseses. The current specifications of the Kansas Department of Transportation (KDOT) control embankment compaction are based on in-situ density and moisture content. In the recent past, KDOT participated in a number of projects that studied feasibility of performance-based specifications, specifically in terms of in-situ soil stiffness measured by non-destructive tests and/or produced by the intelligent compaction (IC) rollers, for quality control/quality assurance of highway embankments. Kansas experience shows that in-situ tests with Lightweight Deflectometer result in stiffness that is highly variable like other available tests. Correlation among different test methods is fair. The intelligent compaction results in very uniform compaction in the spatial direction. However, no existing test results are correlated with the stiffness parameters yielded by such rollers. The IC rollers also can detect soft spots in compacted subgrade. Thus such device can be used in proof rolling of compacted highway embankments. © 2012 American Society of Civil Engineers.

Liu L.,Kansas State University | Hossain M.,Kansas State University | Miller R.W.,Materials and Research Center
Transportation Research Record | Year: 2010

This study investigated the benefits and costs of commonly used thin surface treatments for maintenance of bituminous pavements in Kansas. Cost and performance data were collected from the Kansas Pavement Management Information System for all treatments applied from 1992 to 2006. Results show that seal coats have a short average service life on Interstate highways. The average life on non-Interstate highways is about 4 years. This life is slightly lower than that for other thin surface treatments, including hot-mix asphalt (HMA) overlays. Seal coats also have a significantly lower equivalent uniform annual cost than do all other thin surface treatments in Kansas. A comparison of pavement benefit values before and after application showed that seal coat could not mitigate distresses better than other methods, especially thin HMA overlays. However, its performance is quite similar to that of the modified slurry seal.

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