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Gallivan V.L.,U.S. Federal Highway Administration | Chang G.K.,Transtec Group Inc. | Horan R.D.,Asphalt Institute
Asphalt Paving Technology: Association of Asphalt Paving Technologists-Proceedings of the Technical Sessions | Year: 2011

Intelligent Compaction (IC) is a major innovation in compaction technology that has been studied extensively in the US over the last five years. IC is defined as a process that uses vibratory rollers equipped with a measurement/documentation system that automatically records various critical compaction parameters in real time during the compaction process. The recorded information is then displayed for the roller operator and project personnel to improve the compaction process. Field studies by the authors and other researchers have shown that IC has many potential benefits that can result in better compaction processes and improved process/quality control/acceptance procedures. These benefits are likely to result in the construction of longer lasting asphalt pavements. Suppliers of IC technology have conducted extensive research and development and are geared up to make IC rollers commercially available. In short, the stage is now set for agencies that would like to implement the use of IC technology in a practical manner. It has been a well known fact for decades that effective compaction is a critical step in the construction of quality Hot Mix Asphalt (HMA) pavement. In recent years, the understanding has grown that pavement materials must be properly compacted in the field to obtain the desired long service lives. With this in mind, there have been many improvements and innovations in compaction equipment, as well as in situ test equipment and specifications related to compaction over the years. Manufacturers have been modifying their compaction equipment, State agencies have been modifying their specifications, and contractors have been modifying their processes over the years all in an attempt to improve the compaction of HMA pavements. This paper discusses the 21st century practical efforts to improve the compaction of HMA pavements by using " intelligent" equipment that provides the contractors and agencies real-time information regarding the effectiveness of their compaction operations. The results of multiple field demonstrations have shown that IC mapping of the underlying materials prior to paving can identify weak or non-uniform areas that affect the quality of the HMA pavement compaction efforts. The contractor can optimize rolling operations using IC with increased knowledge of the HMA surface temperatures and roller locations. Thus, IC is a technology that is increasingly being used nationally and internationally and has been shown to provide for greater control and oversight of the compaction process, resulting in improved and more uniform compaction.


Xu Q.,Transtec Group Inc. | Chang G.K.,Transtec Group Inc. | Gallivan V.L.,U.S. Federal Highway Administration | Horan R.D.,Asphalt Institute
Construction and Building Materials | Year: 2012

Conventional pavement analysis and design methods are based on the homogeneous or uniform material model such including the multi-layered analysis program and AASHTO design methods. With the Intelligent Compaction (IC) technology on hot mix asphalt (HMA) involved in recent years, the compaction uniformity of material property can be quantified. This paper intends to study the effects of compaction uniformity on pavement performances using the Bomag IC Evib - a measurement of elastic moduli with 100% coverage of the compaction area. The three dimensional (3-D) finite element (FE) model was built to simulate pavement responses with the heterogeneous HMA moduli derived from the field IC measurements. Then the Mechanistic-Empirical Pavement Design Guideline (M-E PDG) models were used to predict HMA performances of rutting and fatigue life. The geostatisical semivariogram model was studied to evaluate the uniformity of predicted performances. Different from conventional pavement analysis and designs, spatial-distributed heterogeneous moduli of the asphalt layer were considered in this work. Results show that spatial uniformity of material moduli affects pavement performances in terms of the distress severity and uniformity. Less uniform material moduli result in higher rutting depths and shorter fatigue lives. For the case study in this paper, the mean and peak values of fatigue lives for the heterogeneous model are 38.2% and 0.1% of those for the uniform model. A pavement section with overall lower material moduli does not necessarily correspond to inferior performances as the effects from uniformity of material property may dominate other factors. Therefore, it is recommended that the uniformity of pavement layer properties that emulate the typically more variable service condition be considered in future pavement designs and performance predictions. © 2011 Elsevier Ltd. All rights reserved.


Xu Q.,Transtec Group Inc. | Ruiz J.M.,Transtec Group Inc. | Hu J.,Texas State University | Wang K.,Iowa State University | Rasmussen R.O.,Transtec Group Inc.
Thermochimica Acta | Year: 2011

This research aims to evaluate the calorimetry tests for characterizing cement hydration properties and predicting temperature developments of the early-age Portland cement concrete pavement (PCCP). Analytical models are studied to simulate hydration properties, using the measured heat evolution data from both the isothermal and semi-adiabatic tests. HIPERPAV III ® engineering software with these analytical models embedded is used to predict temperature developments of the early-age PCCP. Results show that the maximum hydration time parameter τ corresponds to the maximum activation energy E a. Semi-adiabatic tests result in a lower hydration shape parameter β yet a higher hydration time parameter τ than isothermal tests. As results, the simulated degree of hydration based on semi-adiabatic tests is higher at the early hours, but lower at later hours compared to that based on isothermal tests. This effect is also reflected from the simulated temperature developments of the early-age PCCP. Three engineering projects in this research show that predicted temperatures of the PCCP using hydration parameters determined from semi-adiabatic tests better match actual measurements than that from isothermal tests. © 2010 Elsevier B.V. All rights reserved.


Xu Q.,University of Texas at Austin | Chang G.K.,Transtec Group Inc.
Construction and Building Materials | Year: 2014

In the conventional structural analysis and design of highway pavements including the mechanistic-empirical pavement design guide (MEPDG), the layer properties are considered uniform spatially. This research studies the geospatial heterogeneity of asphalt material property and its influence on structural responses with the intelligent compaction (IC) technology on road construction. Instrumented with the satellite navigation system, accelerometer and computer system, the IC roller measured the material stiffness with 100% coverage. A three-dimensional finite element (FE) model was developed to simulate pavement responses with heterogeneous Bomag Evib as elastic moduli of asphalt materials under vehicle loading. This material model considers heterogeneous material properties with geospatial distribution that more closely reflect the actual field conditions on a typical roadway. The statistics and geostatistical semivariogram model were studied to evaluate the heterogeneity of material moduli and structural responses. A coefficient of semivariogram (Cova) index is proposed to quantify the geospatial heterogeneity. Modeling results demonstrated that geospatial heterogeneity of material elastic moduli, rather than commonly used univariate statistics, affects structural responses spatially in a nonlinear fashion. Heterogeneous moduli distribution results in inferior responses than uniform model. Cova has close values and trends with that of the coefficient of variance for the analysis area with small-space, and it could be used to quantify the heterogeneity. Therefore, the geospatial heterogeneity of material property is recommended to be considered in future pavement analysis to account for the in-service conditions. © 2014 Elsevier Ltd. All rights reserved.


Rasmussen R.O.,Transtec Group Inc
SAE International Journal of Passenger Cars - Mechanical Systems | Year: 2013

Pavements complying with the ISO 10844 standard are an important component of vehicle and tire noise testing. In 2011, a new version of this standard was published, which includes many important changes compared to the 1994 version. As a result, some tracks that complied with the 1994 standard are now nonconforming with the 2011 version. Many tracks are in the process of being resurfaced, particularly before regulations are adopted that require conformance with the new version of the standard. While repaving is costly, it can also lead to opportunity. Pavement engineering encompasses pavement design, materials selection and proportioning, and the selection of construction techniques. Pavement life is also an important engineering criterion. In the case of test tracks, life is most often defined by functional performance including changes in friction, rolling resistance, ride, and in this instance, noise. Optimized pavement engineering often seeks a balance between initial cost and durability. For example, ISO 10844:2011 now permits polymer-modified asphalt binders. While more costly, higher quality binders can delay the onset of raveling, stripping, and other surface deterioration that affects functional performance including noise. Optimized pavement engineering can target a pavement lifespan, which is related to the evolution of the noise measurements over time. A predictable response can also be sought. For example, the ISO 10844:2011 tests for pavement texture and acoustical absorption. These attributes are affected by paving materials and construction technique. Through optimization, specific measurement targets can be engineered for more predictable and consistent test outcomes. 2013 SAE International.


Xu Q.,Transtec Group Inc. | Chang G.K.,Transtec Group Inc.
Automation in Construction | Year: 2016

During conventional road construction, quality control and acceptance (QC/QA) are based on limited spot tests of material density at random locations which may not be representative of the compacted area and may consist of potential bias. This research presented an innovative material-machine-information and human-decision integrated system for adaptive QC/QA using the intelligent compaction (IC) technology to overcome the above limitation of conventional testing. In this integrated system, compaction properties such as material stiffness are monitored in real time with 100% coverage of compacted areas by instrumented IC rollers. By monitoring compaction process and roller-ground interactions, this system can be used to determine compaction target values, which are in-turn fed back to the IC system to optimize compaction efforts and improve construction quality. This approach can also be used to determine compaction uniformity for the as-built in order to assess pavement performance. Recommended further development of the intelligent road construction technology is presented to fully leverage the IC technologies in the future. © 2015 Elsevier B.V. All rights reserved.


Xu Q.,Transtec Group Inc. | Chang G.K.,Transtec Group Inc.
Automation in Construction | Year: 2013

This paper aims to evaluate the effectiveness of IC technology for the asphalt compaction. A framework of field construction and in-situ test control using IC technology was presented and implemented in one engineering project. A computer-aided data analysis method was proposed and implemented, including the univariate and geo-statistics, compaction curve and uniformity. Results show that IC technology can effectively improve the roller patter to achieve more uniform compaction, and the compaction curve identifies the optimum roller pass to help avoid under/over compaction. The trend of Sakai Compaction Control Value (CCV) - a relative index of material stiffness - is consistent with CCV from mapping the underlying subbase layer. This indicates the reflecting effect of underneath layers on upper layers. CCVs from asphalt compaction have a linear relationship with the light-weight-de flectometer moduli of subbase. The compaction uniformity trends indicated by univariate statistics are consistent with that indicated by semivariograms for this case study. © 2012 Elsevier B.V. All rights reserved.


Xu Q.,Transtec Group Inc. | Chang G.K.,Transtec Group Inc. | Gallivan V.L.,Gallivan Consulting Inc.
IEEE/ASME Transactions on Mechatronics | Year: 2015

Intelligent compaction (IC) is an innovative technology that has been used in road and earthwork construction. However, the current IC technology is unable to measure material density directly as the acceptance criteria by owner agencies. To tackle this issue, the authors have developed a sensing-information-statistics integrated model to predict asphalt material density for 100% coverage of construction area. Instrumented with the satellite navigation system, accelerometer, and infrared sensors, IC rollers measure mechanical responses of roller drums and material temperature in real time. With these measurements, panel data models - including both the multivariate linear and nonlinear models - were developed to predict asphalt material density. A reasoning model was proposed to estimate idiosyncratic errors due to uncertainty of measurements. An information management software was developed to analyze IC measurements with univariate statistics and geo-statistical models. Statistical models were implemented and validated with data collected from four paving projects in the US. Results indicate that the multivariate nonlinear panel data model can predict asphalt material density at the project level for 100% coverage of the construction zone within reasonable accuracy. Therefore, this model may serve as an enhanced quality control and acceptance tool for asphalt pavement construction to improve consistency and uniformity and long-term performances. © 2015 IEEE.


Xu Q.,Transtec Group Inc. | Chang G.K.,Transtec Group Inc. | Gallivan V.L.,Office of Pavement Technology
Construction and Building Materials | Year: 2012

Intelligent compaction (IC) on hot-mix-asphalt (HMA) is an emerging, yet still evolving technology for the constructions of highway system, airfield, and parking lots. IC produces massive amounts of geospatial data with 100% coverage of the compacted area in real time, which needs to be effectively analyzed and managed for quality control and acceptance (QC/QA). Accordingly, in this paper a systematic method using both the univariate and geo-statistical modeling techniques was developed for the IC data analysis and management. A data extraction method was proposed to categorize and extract IC data on different layer levels. Consequently, linear regression was performed to correlate IC Measurement Values (ICMVs) with random spot measurements. The semivariogram model was studied to evaluate the compaction uniformity, and the compaction curve was developed to identify the optimum number of roller passes. The systematic method with multiple statistical models was coded for numerical solutions, and demonstrated for eight HMA IC projects. Results indicate that compaction uniformity improves "from the ground, up": subbase, HMA base, and then surface course. The compaction curve can help set the compaction target for QC/QA. ICMV has shown consistent linear correlations with spot measured deflections and material modulus, but it has inconsistent correlations with densities. Multivariate correlations indicate that multiple factors, including the ICMV of underlying layers and temperatures of HMA, affect the ICMV of the HMA layer. © 2012 Elsevier Ltd. All rights reserved.


Rasmussen R.O.,Transtec Group Inc.
SAE Technical Papers | Year: 2013

Pavements complying with the ISO 10844 standard are an important component of vehicle and tire noise testing. In 2011, a new version of this standard was published, which includes many important changes compared to the 1994 version. As a result, some tracks that complied with the 1994 standard are now nonconforming with the 2011 version. Many tracks are in the process of being resurfaced, particularly before regulations are adopted that require conformance with the new version of the standard. While repaving is costly, it can also lead to opportunity. Pavement engineering encompasses pavement design, materials selection and proportioning, and the selection of construction techniques. Pavement life is also an important engineering criterion. In the case of test tracks, life is most often defined by functional performance including changes in friction, rolling resistance, ride, and in this instance, noise. Optimized pavement engineering often seeks a balance between initial cost and durability. For example, ISO 10844:2011 now permits polymer-modified asphalt binders. While more costly, higher quality binders can delay the onset of raveling, stripping, and other surface deterioration that affects functional performance including noise. Optimized pavement engineering can target a pavement lifespan, which is related to the evolution of the noise measurements over time. A predictable response can also be sought. For example, the ISO 10844:2011 tests for pavement texture and acoustical absorption. These attributes are affected by paving materials and construction technique. Through optimization, specific measurement targets can be engineered for more predictable and consistent test outcomes. Copyright © 2013 SAE International.

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