TxDOT 5-6740-01: Implementation of Intelligent Compaction Technology for Improving Compaction Quality of Soil and Base in Texas

Funding Agency: Texas Department of Transportation | Duration: July 2014 – June 2017 (3 Years) | PI: Soheil Nazarian

TxDOT is proudly committed to the FHWA Every Day Counts 2 (EDC2) initiative and to be a lead state in the implementation of the Intelligent Compaction (IC) technology in earthwork. Currently five districts (total 14 projects) are using or have programmed the use of Intelligent Compaction in their daily operations. The main objective of this project is to capitalize on the new IC specification for implementation of IC technology developed through TxDOT research Project 0-6740. The specific objectives of this project include: (1) developing and deploying a training program for the TxDOT engineers and inspectors, (2) supporting the districts in implementing the IC technology in their districts, (3) implementing a field monitoring program to quantify the long-term benefits of the IC technology, and (4) assisting the CST in evaluating and incorporating the new IC specification for inclusion in the new specification book.

TxDOT Project 0-6923 “Develop Guidelines and Design Program for Hot-Mix Asphalt Containing RAP, RAS, and Other Additives through a Balanced Mix-Design Process.”

Soheil Nazarian, PhD, PE (RS), Imad Abdallah, PhD, Jose Garibay, MS
Victor Garcia, MS
Figure 1 – Example of Performance Diagram for Rutting and Cracking Potentials of AC Mixtures

The pavement community has focused more on implementing sustainable measures such as recycling previously used materials into new pavements to reduce the use of new mineral aggregates, asphalt binder, and landfill space. The increase in the use of recycled materials, recycling agents, binder additives and warm mix asphalt technologies have altered the mechanical properties of mixtures, especially cracking, in a way that volumetric mix design alone is not sufficient any more. Without a detailed mix design process, specific ranges and limits, and a mix design program to design and balance the characteristics of AC mixtures during the design stage, the application of these innovative and sustainable practices for asphalt concrete (AC) mixtures can potentially increase the risk of cracking and may negatively impact the long-term durability of the AC mixtures. The Texas Department of Transportation is concerned about current mix design practices since AC mixtures in some cases last less than their intended service lives. Even though performance test methods such as the Hamburg wheel-tracking test and Overlay test have been specified during the mix design process, it is critically important to evaluate and implement a design process and test protocols for optimizing the volumetric properties and engineering the mechanical performance of AC mixtures through a “Balanced Mix Design” process. The main goal of this project is to conduct a comprehensive evaluation of the current mix design process and test protocols to incorporate the concept of “Balanced Mix Design” into a program for routine design of AC mixtures.

5-6679-01: Implementation of Performance Life of Various HMA Mixes in Texas

Danniel Rodriguez

Figure 1- PERMIT Online-Tool Developed Under TxDOT Research Project 0-6679.

Pavement engineers in Texas subjectively estimate the service lives of various hot-mix asphalt (HMA) mixtures as part of the life-cycle cost analysis considering the staged design and rehabilitation of flexible pavements. In response, a data-driven, HMA performance life assessment framework and the resulting HMA mixture service lives were proposed under TxDOT research project 0-6679. The technology transfer of these processes resulted in the online-tool prototype: Performance Life of Mixes in Texas (PERMIT). PERMIT is a database and online-tool composed of datamining and merging of Letting Database, Design and Construction Information System (DCIS), and Pavement Management Information System (PMIS). This implementation project will employ those performance life assessment methodologies and PERMIT prototype developed under TxDOT project 0-667 to deploy a web-application that provides the performance life and deterioration trends of various HMA mixtures in Texas. The relational database behind this tool and the accompanying graphical user interface (GUI) will also be expanded and modified to enable a user-friendly build of complex queries to retrieve construction information from Site Manager Database. This web-application will be developed and implemented to assist TxDOT engineering personnel with their decision processes as-related to HMA mix longevity and pavement design, and rehabilitation and maintenance programming.

EPRI: Exploratory Study of Use of Surface Waves to Determine Defects in Concrete

Funding Agency: Electrical Power Research Institute | Duration: 2013-2014 (9 Months) | PI: Soheil Nazarian | Research report available upon request

Freeze-thaw and alkali-silica reaction (ASR) damage in concrete infrastructure is a major concern. The progression of damage due to freeze-thaw and ASR has been widely monitored with conventional destructive methods, such as mechanical testing and petrography on drilled cores. Focus of this exploratory study is on applicability and usefulness of surface wave methods to characterize the severity of map cracking and surface defects in structures impacted by ASR and freeze-thaw.

TXDOT 0-6740: Improvement of Construction Quality Control by Using Intelligent Compaction Technology for Base and Soil

Funding Agency: Texas Department of Transportation | Duration: 2012-2013 (1 Year) | Research Report

Current practice for field compaction quality control and acceptance for base and soil layers is based on the compacted density and moisture content by nuclear density gauge (NDG). Since density measurements are truly spot tests, they cannot represent the quality and uniformity of compaction in a continuous manner. Intelligent compaction (IC) technique is a fast-developing technology for base and soil compaction quality control and acceptance. The primary objective of this project is to improve the process of accepting compacted materials to ensure quality, performance and durability using IC technology. Practical test protocols and specifications are being developed to improve the general quality and acceptance of compaction for subgrade, embankment, and base construction with available IC rollers.

NCHRP 10-84: Modulus-Based Construction Specification for Compaction of Earthwork and Unbound Aggregate

Funding Agency: National Academy of Sciences | Duration: 2010-2014 (4 Year) | PI: Soheil Nazarian | Research report available upon request

Earthwork and unbound aggregates are a significant portion of the construction of highway pavements and structures and play an important role in their performance. However, measurement of the dry density and moisture content of earthwork and unbound aggregates for construction control, while relatively straightforward and practical, does not provide as direct a connection between design and construction, as there could be if mechanical properties such as moduli were used. Several test methods and devices are available to determine the stiffness or modulus of earthwork and unbound aggregates in the field. Therefore, a rigorous modulus-based specification must provide criteria or limits related to long-term performance of the earthwork or unbound aggregate as well as to compaction at the time of construction. The objective of this research is in collaboration with the Louisiana Transportation Research Center and The University of Texas at Arlington to develop a straightforward, and well-defined modulus-based specification for compaction of earthwork and unbound aggregates that is based on field measurement of the stiffness or modulus and moisture content of the compacted earthwork, that can be correlated with design modulus values, and that is founded on a comprehensive review of the current literature on the long-term behavior of various soils and unbound aggregates in terms of the principles of unsaturated soil mechanics.

TxDOT IAC-NTP1: Assessing the Variability of Current Overlay Test Procedure

PI: Soheil Nazarian | Research report available upon request

The main objective of the study was to investigate the sources of variability in the performance measures from overlay tests. The two main sources of variability, apart from material characteristics, are the specimen preparation process and the elapsed time between preparation and testing. A series of tests was conducted in accordance with Tex-248-F to quantify the OT variability in close collaboration with the TxDOT Flexible Pavement Branch: Construction Division from Austin, Texas. This study consists of testing samples at the Center for Transportation Infrastruc ture Systems (CTIS) asphalt laboratory at UTEP using two different OT systems. The resul ts obtained at UTEP will be compared with those carried on similar specimens at TxDOT Construction Division (CST). This study was performed in systematic approach to minimize the impact of variability introduced during specimen preparation

TxDOT IAC-NTP2: CTIS Tasked by TxDOT to Evaluate Interstate Highway 10 in El Paso

PI: Soheil Nazarian | Research report available upon request

CTIS is assisting TxDOT with pavement evaluation of Interstate Highway 10 corridor in El Paso. CTIS staff are using ground penetrating radar (GPR) method to perform nondestructive evaluation of the IH10 to assess the structural health of the pavement and bridges. GPR method is an electromagnetic nondestructive testing method widely applied on bridge decks and pavements for evaluation of thicknesses, rebar arrangement and location, concrete deterioration and potential for delamination or debonding. The effort included testing on the bridge deck at Cotton Avenue. Another location of interest is a bonded concrete overlay section within the corridor. The team were locating debonded areas and trying to investigate areas where water is trapped in the concrete layers that can eventually lead to accelerated deterioration of pavement.

TXDOT 0-6679: Performance Life of Various Mixes in Texas

Funding Agency: Texas Department of Transportation | Duration: 2011-2014 (3 Years) | PI: Soheil Nazarian | Research report available upon request

One of the important inputs into current pavement design programs is the performance lives of HMA mixes since they significantly impact the life cycle cost analyses and the ultimate selection of the HMA type., the estimated performance life of different HMA mixes (including the frequency of overlay) by the designers is currently subjective. The main goal of this project is to objectively recommend the most likely service lives of different mixes used in Texas as a function of the mix properties, type and quality of construction, pavement structure, frequency of preventive maintenance, traffic volume, and the environmental characteristics.

EPMPO: Development of a Sustainable Performance-Based Methodology for Strategic Metropolitan Planning Based on MAP-21​

Funding Agency: El Paso Metropolitan Planning Organization | Duration: 2016-2017 (1 Year)​ | PI: Carlos Chang​ | Research report available upon request​

A sustainable performance-based evaluation methodology with 26 performance measures has been developed for El Paso MPO. The methodology covers four planning scales: within community, community to community, community to region, and region to region. The implementation of this methodology will allow El Paso MPO to better achieve its strategic goals for the well-being of the community and the region.

Quantification of the Impact of Roadway Conditions on Emissions

Funding Agency: Texas Department of Transportation | Duration: 2014-2016 (2 Years) | PI: Carlos M. Chang

This project involves quantifying the impact of roadway conditions on vehicular emissions and developing detailed guidance to assist TxDOT in improving maintenance strategies to reduce these emissions. The researchers will quantify the vehicular emissions associated with different conditions of flexible pavement, continuously reinforced concrete pavement (CRCP), and jointed concrete pavement (JCP), and evaluate the effectiveness of different maintenance strategies in reducing emissions on these roadways. This research will demonstrate that roadway rehabilitation is an effective means of reducing vehicle emissions.

Seismic Testing for Track Substructure (Ballast and Subgrade) Assessment

Funding Agency: Federal Railroad Administration | Duration: 2012-2014 (2 Years) | PI: Soheil Nazarian

This project proposes to use seismic wave propagation principles (a non-destructive method) to develop a railroad track substructure (ballast and subgrade) condition assessment system. Currently there is no established tool or system available that quantitatively measures the mechanical properties of the layers comprising a track system. In cooperation with the Rail Transportation and Engineering Center at the University of Illinois at Urbana-Champaign and the University of Massachusetts at Amherst, a system for quickly, nondestructively, and quantitatively assessing the engineering properties of the track substructure (ballast and subgrade) is being developed. The resulting system will be used in conjunction with Ground Penetrating Radar (GPR) to not only measure engineering properties but also determine the cause(s) of the potential problem areas, i.e., degraded track or reduced performance.

FHWA DTFH61-12-R-00040: Pavement Structural Evaluation at the Network Level

Funding Agency: Federal Highway Administration | Duration: 2012-2014 (2 Years) | PI: Soheil Nazarian

CTIS subcontract by AMEC is conducting research for Federal Highway Administration (FHWA) on a project titled “pavement Structural Evaluation at the Network Level”. The objectives of the project are:

1) To assess, evaluate and validate the capability of the RWD and the TSD (and any other traffic speed continuous deflection (or other pavement response that can be reliably related to pavement structural condition) devices that may have been developed since these efforts) for pavement structural evaluation at the network level for use in pavement management application and decision making.

2) If one or more of the available devices are capable of meeting the above stated objective, to develop analysis methodologies for enabling their use in pavement management. If they do not have the capability to meet the objective, to develop recommendations to further develop promising device(s) and/or technologies.

TXDOT 0-6658: Collection of Materials and Performance Data for Texas Flexible Pavements and Overlays

Funding Agency: Texas Department of Transportation | Duration: 2010-2015 (5 Years) | PI: Soheil Nazarian

The primary objective of this project is in collaboration with Texas Transportation Institute to collect materials and pavement performance data on a minimum of a 100 highway test sections around Texas. That information can be used to calibrate and validate mechanistic-empirical (M-E) design models. The data will also serve as an ongoing reference data source and/or diagnostic tool for TxDOT engineers and other transportation professionals.

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TxDOT 0-6812: Updated Testing Procedures for Long Life Heavy Duty Stabilized Bases

Funding Agency: Texas Department of Transportation | Duration: May 2014 - March 2016 (2 Years) | PI: Reza Ashtiani

TxDOT is in the process of evaluating new approaches and laboratory test methods for characterization of the fatigue performance of the cement treated base layers. The new approach is required to be all inclusive for statewide application and incorporation into the new Mechanistic Empirical Design Guide (TexME). Three-point bending beam fatigue test is currently used for the determination of the modulus of rupture of the cement-treated mixes. This test proved to be impractical for lightly-stabilized systems as the specimen tends to disintegrate during transportation to the test setup. Additionally, discrepancies associated with specimen preparation and non-uniform density distribution in large samples were found to be an added concern that greatly jeopardizes the accuracy of the performance prediction models. Therefore, there is an urgent need for a simple and practical fatigue test that provides inputs to the TexME structural design program. This research project provides an alternative laboratory testing protocol for mechanistic characterization of the cement treated base layers to meet the need. This project will focus on identification, evaluation and validation of a practical laboratory testing protocol that will be implemented by TxDOT to characterize fatigue performance of the pavement structures with cement stabilized base layers.

TxDOT 464MITA047 IAC - FHWA Task 3e - EDC 2 National Deployment of Intelligent Compaction

Funding Agency: FHWA | Duration: May 2014 - March 2015 (1 Year) | PI: Soheil Nazarian | Research report available upon request

The main goal of this project is to collect necessary data for a comprehensive evaluation of the candidate intelligent compaction (IC) retrofit kits for compaction of hot mix asphalt (HMA), base, and subgrade layers. One of the key components of this project is two equipment rodeos. A test plan for conduction of the two rodeos is provided here. The test plan provides detailed information on installing and operating the IC retrofit kits on selected asphalt and soil rollers, performing side-by-side comparisons of retrofitted rollers and selected factory-supplied IC rollers, and implementing NDT spot tests (as well as sampling and coring if necessary) for correlation purposes. The main objectives of the equipment rodeos are the following items: - Demonstrating IC retrofit kit installation and operation to targeted DOTs - Identifying and addressing the potential challenges associated with retrofitting process and obtaining on-site GPS coordinates - Evaluating the proper installation of the retrofit kits with additional embedded geophones and installed accelerometers during the operation process - Establishing the variability of each specific IC roller as well as retrofitted rollers with respect to inherent field and materials variation, and - Investigating the correlation between selected NDT test results and IC data from retrofitted and factory installed IC kits

TxDOT 0-6815: Improved Overlay Tester for Fatigue Cracking Resistance of Asphalt Mixtures

Funding Agency: Texas Department of Transportation | Duration: July 2014 - June 2016 (2 Years) | PI: Soheil Nazarian

Fatigue cracking of hot mix asphalt continues to be a recurring problem in Texas. Pavements with fatigue cracking deteriorate rapidly under the combination of traffic, moisture, and aging of the asphalt layer. Similar to Hamburg Wheel Tracking device (HWTD) for rutting potential, TxDOT has implemented the Overlay Tester (OT) to evaluate the cracking susceptibility and resistance to reflective cracking of hot mix asphalt (HMA). The OT is a relatively simple but empirical laboratory method. Despite several previous attempts to improve OT so that parameters related to quantify resistance to fatigue cracking can be measured, additional work in that area is required. Recent studies have brought about some concerns about the utility of the OT in dense graded HMA mixes such as Types C and D, which make up about 75% of all HMA used in Texas. The use of OT to measure resistance to fatigue cracking of HMA reliably and in a robust manner is greatly needed for all mixture types and HMA specifications. Through a systematic approach, full consideration of the previous work on the subject and in consultation with the manufacturers (see letter of commitment), we will evaluate and improve the hardware and software, laboratory test procedures and specifications of the OT to allow direct measurement of fatigue properties of asphalt mixtures with much less variation. This project will focus on evaluating the previous work done by TTI under the TxDOT funded research projects, and other state DOTs’ experiences, to modify the current OT to measure and characterize the fatigue properties of the HMA laid down by the Districts.