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Two-dimensional digital image correlation (2D-DIC) is a widely used optical technique to measure displacement and strain during asphalt concrete (AC) testing. An accurate 2-D DIC measurement can only be achieved when the camera's principal axis is perpendicular to the planar specimen surface. However, this requirement may not be met during testing due to device constraints. This paper proposes a simple and reliable method to correct errors induced by non-perpendicularity. The method is based on image feature matching and rectification. No additional equipment is needed. A theoretical error analysis was conducted to quantify the effect of a non-perpendicular camera alignment on measurement accuracy. The proposed method was validated numerically using synthetic images and experimentally in an AC fracture test. It achieved relatively high accuracy, even under considerable camera rotation angle and large deformation. As a pre-processing technique, the proposed method showed promising performance in assisting the recently developed CrackPropNet for automated crack propagation measurement under a non-perpendicular camera alignment., Comment: Journal of Transportation Engineering, Part B: Pavements

Resurfacing a moderately deteriorated Portland cement concrete (PCC) pavement with asphalt concrete (AC) layers is considered an efficient rehabilitation practice. However, reflective cracks may develop shortly after resurfacing because of discontinuities (e.g. joints and cracks) in existing PCC pavement. In this paper, a new accelerated full-scale testing approach was developed to study reflective crack growth in AC overlays. Two hydraulic actuators were used to simulate a moving dual-tire assembly with a loading rate of more than five-thousand-wheel passes per hour. A load cycle consists of three steps, simulating a tire approaching, moving across, and leaving a PCC discontinuity. Experiments were conducted to compare the reflective crack behaviour of two overlay configurations. Both test sections were fully cracked in less than an hour. The initiation and propagation of reflective cracks were explicitly documented using crack detectors in conjunction with a camera. The proposed full-scale testing protocol offers a repeatable and efficient approach to systematically investigate the effects of various overlay configurations, thus enabling the identification of optimal design against reflective cracking.

This article proposes a deep neural network, namely CrackPropNet, to measure crack propagation on asphalt concrete (AC) specimens. It offers an accurate, flexible, efficient, and low-cost solution for crack propagation measurement using images collected during cracking tests. CrackPropNet significantly differs from traditional deep learning networks, as it involves learning to locate displacement field discontinuities by matching features at various locations in the reference and deformed images. An image library representing the diversified cracking behavior of AC was developed for supervised training. CrackPropNet achieved an optimal dataset scale F-1 of 0.755 and optimal image scale F-1 of 0.781 on the testing dataset at a running speed of 26 frame-per-second. Experiments demonstrated that low to medium-level Gaussian noises had a limited impact on the measurement accuracy of CrackPropNet. Moreover, the model showed promising generalization on fundamentally different images. As a crack measurement technique, the CrackPropNet can detect complex crack patterns accurately and efficiently in AC cracking tests. It can be applied to characterize the cracking phenomenon, evaluate AC cracking potential, validate test protocols, and verify theoretical models.

Cracking is a common failure mode in asphalt concrete (AC) pavements. Many tests have been developed to characterize the fracture behavior of AC. Accurate crack detection during testing is crucial to describe AC fracture behavior. This paper proposed a framework to detect surface cracks in AC specimens using two-dimensional digital image correlation (DIC). Two significant drawbacks in previous research in this field were addressed. First, a multi-seed incremental reliability-guided DIC was proposed to solve the decorrelation issue due to large deformation and discontinuities. The method was validated using synthetic deformed images. A correctly implemented analysis could accurately measure strains up to 450\%, even with significant discontinuities (cracks) present in the deformed image. Second, a robust method was developed to detect cracks based on displacement fields. The proposed method uses critical crack tip opening displacement ($\delta_c$) to define the onset of cleavage fracture. The proposed method relies on well-developed fracture mechanics theory. The proposed threshold $\delta_c$ has a physical meaning and can be easily determined from DIC measurement. The method was validated using an extended finite element model. The framework was implemented to measure the crack propagation rate while conducting the Illinois-flexibility index test on two AC mixes. The calculated rates could distinguish mixes based on their cracking potential. The proposed framework could be applied to characterize AC cracking phenomenon, evaluate its fracture properties, assess asphalt mixture testing protocols, and develop theoretical models.

ERDC/CERL TR-17-9 Installation Technology Transition Program (ITTP) Development and Testing of Geopolymers for Soil Stabilization on Military Installations Construction Engineering Research Laboratory Ghassan K. Al-Chaar, Peter B. Stynoski, Kaushik Sankar, Marion L. Banko, Waltraud M. Kriven, and Imad Al-Qadi April 2017 Approved for public release; distribution is unlimited. The U.S. Army Engineer Research and Development Center (ERDC) solves the nation’s toughest engineering and environmental challenges. ERDC develops innovative solutions in civil and military engineering, geospatial sciences, water resources, and environmental sciences for the Army, the Department of Defense, civilian agencies, and our nation’s public good. Find out more at www.erdc.usace.army.mil. To search for other technical reports published by ERDC, visit the ERDC online library at http://acwc.sdp.sirsi.net/client/default. Installation Technology Transition Program (ITTP) ERDC/CERL TR-17-9 April 2017 Development and Testing of Geopolymers for Soil Stabilization on Military Installations Ghassan K. Al-Chaar, Peter B. Stynoski, and Marion L. Banko Construction Engineering Research Laboratory U.S. Army Engineer Research and Development Center 2902 Newmark Drive Champaign, IL 61822 Kaushik Sankar, Waltraud M. Kriven, and Imad Al-Qadi University of Illinois at Urbana-Champaign Department of Materials Science and Engineering 1304 W Green Street Urbana, IL 61801 Final report Approved for public release; distribution is unlimited. Prepared for U.S. Army Corps of Engineers Washington, DC 20314-1000 Under Project P2 457492-A1010, “Geopolymer Soil Stabilized Platforms for Semi- Permanent Structures Used for Storage and Corrosion Prevention of Critical Parts and Equipment (RDT&E)” ERDC/CERL TR-17-9 ii Abstract The Department of Defense (DoD) requires a high-strength expedient soil-stabilization technology to use as a pavement. This study investigated the design and testing of an alternative to ordinary P

This paper presents a system of systems (SoS) Biofuel model considering the interdependency among the systems involved in biofuel development, including biofuel refinery location, transportation infrastructure, agricultural production and markets, environment, and social communities. The model provides the optimal infrastructure development and land-use allocation for biofuel production in a region considering socio-economic and water quality and quantity effects. The optimal development plan quantifies economic and hydrologic outputs and specifies biofuel refinery locations and capacities, refinery operations, land allocation between biofuel and food crops, optimal shipments of products and feedstock, and transportation infrastructure. The model is formulated as a mixed integer linear program (MILP) and is solved by an algorithm developed specifically to cope with the large size of the optimization problem. In addition to the development of the SoS-Biofuel model, this paper demonstrates the functionality of the model and its ability to analyze the effects of interdependency among subsystems by applying it to a watershed in Illinois. The SoS-Biofuel model is used to investigate the effects of different biofuel polices on infrastructure needs and related environmental consequences, highlighting the interdependencies inherent in the optimal development of the entire system.

This paper presents a system of systems (SoS) Biofuel model considering the interdependency among the systems involved in biofuel development, including biofuel refinery location, transportation infrastructure, agricultural production and markets, environment, and social communities. The model provides the optimal infrastructure development and land-use allocation for biofuel production in a region considering socio-economic and water quality and quantity effects. The optimal development plan quantifies economic and hydrologic outputs and specifies biofuel refinery locations and capacities, refinery operations, land allocation between biofuel and food crops, optimal shipments of products and feedstock, and transportation infrastructure. The model is formulated as a mixed integer linear program (MILP) and is solved by an algorithm developed specifically to cope with the large size of the optimization problem. In addition to the development of the SoS-Biofuel model, this paper demonstrates the functionality of the model and its ability to analyze the effects of interdependency among subsystems by applying it to a watershed in Illinois. The SoS-Biofuel model is used to investigate the effects of different biofuel polices on infrastructure needs and related environmental consequences, highlighting the interdependencies inherent in the optimal development of the entire system.

This paper presents a system of systems (SoS) Biofuel model considering the interdependency among the systems involved in biofuel development, including biofuel refinery location, transportation infrastructure, agricultural production and markets, environment, and social communities. The model provides the optimal infrastructure development and land-use allocation for biofuel production in a region considering socio-economic and water quality and quantity effects. The optimal development plan quantifies economic and hydrologic outputs and specifies biofuel refinery locations and capacities, refinery operations, land allocation between biofuel and food crops, optimal shipments of products and feedstock, and transportation infrastructure. The model is formulated as a mixed integer linear program (MILP) and is solved by an algorithm developed specifically to cope with the large size of the optimization problem. In addition to the development of the SoS-Biofuel model, this paper demonstrates the functionality of the model and its ability to analyze the effects of interdependency among subsystems by applying it to a watershed in Illinois. The SoS-Biofuel model is used to investigate the effects of different biofuel polices on infrastructure needs and related environmental consequences, highlighting the interdependencies inherent in the optimal development of the entire system.

This study evaluated 18 pavement sections located in high-traffic highways in Virginia to find a premium pavement design with a life span of 40 years or more using current and past field experience. The selected pavement sections were thought to perform well. Eight flexible pavements, six composite pavements, two continuously reinforced concrete pavements, and two jointed plain concrete pavements were investigated. Field testing consisted of (1) falling weight deflectometer (FWD) testing to assess the structural capacity of the different pavements and to backcalculate the pavement layer materials' moduli, (2) ground-penetrating radar (GPR) scanning to determine layer thicknesses and to locate any abnormalities inside the pavements, (3) digital imaging to determine condition indices, (4) longitudinal profile measurements to calculate International Roughness Index, and (5) coring and boring to perform material characterization of pavement layers. Hot mix asphalt tests included resilient modulus and creep compliance. Concrete was tested for compressive strength. The analysis of the collected data suggests that premium pavement designs can be obtained. The field investigations suggest that all the tested sites are performing satisfactorily and show very low structural distress. Limited material-related problems were found at some sites, which induced non-load related distresses. It was also confirmed that FWD, GPR, and digital imaging are very useful tools to assess the condition of existing pavements. Since the three categories of pavements (flexible, composite, and rigid) were found to perform well, the study recommends that evaluation of other pavement sections, which are thought to perform in a less than optimal state, be conducted to define the causes of the less than desired performance. The selection of the most appropriate premium pavement design should be based on a detailed life-cycle cost analysis; hence, such analysis should be performed. Mechanistic empiric

A ground-penetrating radar (GPR) system was used to collect data over the different pavement sections of the Virginia Smart Road from June 1999 until December 2002. Three antennae at different frequencies were used for this research. The collected data were successfully used to evaluate the physical GPR detection limitations, to evaluate the GPR accuracy for pavement layer thickness determination, to control the installation of three different types of reinforcing meshes installed within the pavement, and to estimate the in-situ complex dielectric constant of several types of hot-mix asphalt (HMA). The data analysis results were verified by the well-documented structure and composition of each section of the road, in addition to the embedment of 35 copper plates (perfect electromagnetic reflectors) at the different layer interfaces during construction of the pavement. It was found that GPR is a feasible nondestructive tool to estimate the layer thicknesses of bound and unbound aggregate layers, HMA layers, and concrete slabs. However, interface detection can be altered if the layers have comparable dielectric constants. A technique was developed to estimate the frequency-dependent in-situ complex dielectric constant of HMA materials. Results have shown that the effect of the variations of the dielectric properties within the GPR bandwidth is insignificant vis-a-vis the accuracy of thickness estimation. The use of GPR as a quality control tool to verify the success of steel reinforcing mesh installation was also found to be feasible. Given the success of using GPR for the aforementioned applications in the Virginia Smart Road, it is recommended that the Virginia Department of Transportation use GPR more frequently as a quality control tool during new pavement construction projects and as an assessment tool prior to project rehabilitation and as part of Virginia's pavement management system.

Laboratory fatigue testing was performed on six Superpave HMA mixtures in use at the Virginia Smart Road. Evaluation of the applied strain and resulting fatigue life was performed to fit regressions to predict the fatigue performance of each mixture. Differences in fatigue performance due to field and laboratory production and compaction methods were investigated. Also, in-situ mixtures were compared to mixtures produced accurately from the job mix formula to determine if changes occurring between the laboratory and batch plant significantly affected fatigue life. Results from the fatigue evaluation allowed verification of several hypotheses related to mixture production and compaction and fatigue performance. It was determined that location within the pavement surface, such as inner or outer wheelpath or center-of-lane, did not significantly affect laboratory fatigue test results, although the location will have significant effects on in-situ fatigue life. Also the orientation of samples cut from an in-situ pavement (parallel or perpendicular to the direction of traffic) had only a minor effect on the laboratory fatigue life, because the variability inherent in the pavement due to material variability is greater than the variability induced by compaction. Fatigue life of laboratory-compacted samples was found to be greater than fatigue life of field-compacted samples; additionally, the variability of the laboratory compacted mixture was found to be less than that of the field-compacted samples. However, it was also found that batch-plant production significantly reduces specimen variability as compared to small-batch laboratory production when the same laboratory compaction is used on both specimen sets. Finally, for Smart Road mixtures produced according to the job mix formula, the use of polymer-modified binder or stone matrix asphalt was shown to increase the expected fatigue life. However, results for all mixes indicated that fatigue resistance rankings might c

Laboratory fatigue testing was performed on six Superpave HMA mixtures in use at the Virginia Smart Road. Evaluation of the applied strain and resulting fatigue life was performed to fit regressions to predict the fatigue performance of each mixture. Differences in fatigue performance due to field and laboratory production and compaction methods were investigated. Also, in-situ mixtures were compared to mixtures produced accurately from the job mix formula to determine if changes occurring between the laboratory and batch plant significantly affected fatigue life. Results from the fatigue evaluation allowed verification of several hypotheses related to mixture production and compaction and fatigue performance. It was determined that location within the pavement surface, such as inner or outer wheelpath or center-of-lane, did not significantly affect laboratory fatigue test results, although the location will have significant effects on in-situ fatigue life. Also the orientation of samples cut from an in-situ pavement (parallel or perpendicular to the direction of traffic) had only a minor effect on the laboratory fatigue life, because the variability inherent in the pavement due to material variability is greater than the variability induced by compaction. Fatigue life of laboratory-compacted samples was found to be greater than fatigue life of field-compacted samples; additionally, the variability of the laboratory compacted mixture was found to be less than that of the field-compacted samples. However, it was also found that batch-plant production significantly reduces specimen variability as compared to small-batch laboratory production when the same laboratory compaction is used on both specimen sets. Finally, for Smart Road mixtures produced according to the job mix formula, the use of polymer-modified binder or stone matrix asphalt was shown to increase the expected fatigue life. However, results for all mixes indicated that fatigue resistance rankings might c

A ground-penetrating radar (GPR) system was used to collect data over the different pavement sections of the Virginia Smart Road from June 1999 until December 2002. Three antennae at different frequencies were used for this research. The collected data were successfully used to evaluate the physical GPR detection limitations, to evaluate the GPR accuracy for pavement layer thickness determination, to control the installation of three different types of reinforcing meshes installed within the pavement, and to estimate the in-situ complex dielectric constant of several types of hot-mix asphalt (HMA). The data analysis results were verified by the well-documented structure and composition of each section of the road, in addition to the embedment of 35 copper plates (perfect electromagnetic reflectors) at the different layer interfaces during construction of the pavement. It was found that GPR is a feasible nondestructive tool to estimate the layer thicknesses of bound and unbound aggregate layers, HMA layers, and concrete slabs. However, interface detection can be altered if the layers have comparable dielectric constants. A technique was developed to estimate the frequency-dependent in-situ complex dielectric constant of HMA materials. Results have shown that the effect of the variations of the dielectric properties within the GPR bandwidth is insignificant vis-a-vis the accuracy of thickness estimation. The use of GPR as a quality control tool to verify the success of steel reinforcing mesh installation was also found to be feasible. Given the success of using GPR for the aforementioned applications in the Virginia Smart Road, it is recommended that the Virginia Department of Transportation use GPR more frequently as a quality control tool during new pavement construction projects and as an assessment tool prior to project rehabilitation and as part of Virginia's pavement management system.

This study evaluated 18 pavement sections located in high-traffic highways in Virginia to find a premium pavement design with a life span of 40 years or more using current and past field experience. The selected pavement sections were thought to perform well. Eight flexible pavements, six composite pavements, two continuously reinforced concrete pavements, and two jointed plain concrete pavements were investigated. Field testing consisted of (1) falling weight deflectometer (FWD) testing to assess the structural capacity of the different pavements and to backcalculate the pavement layer materials' moduli, (2) ground-penetrating radar (GPR) scanning to determine layer thicknesses and to locate any abnormalities inside the pavements, (3) digital imaging to determine condition indices, (4) longitudinal profile measurements to calculate International Roughness Index, and (5) coring and boring to perform material characterization of pavement layers. Hot mix asphalt tests included resilient modulus and creep compliance. Concrete was tested for compressive strength. The analysis of the collected data suggests that premium pavement designs can be obtained. The field investigations suggest that all the tested sites are performing satisfactorily and show very low structural distress. Limited material-related problems were found at some sites, which induced non-load related distresses. It was also confirmed that FWD, GPR, and digital imaging are very useful tools to assess the condition of existing pavements. Since the three categories of pavements (flexible, composite, and rigid) were found to perform well, the study recommends that evaluation of other pavement sections, which are thought to perform in a less than optimal state, be conducted to define the causes of the less than desired performance. The selection of the most appropriate premium pavement design should be based on a detailed life-cycle cost analysis; hence, such analysis should be performed. Mechanistic empiric

Laboratory fatigue testing was performed on six Superpave HMA mixtures in use at the Virginia Smart Road. Evaluation of the applied strain and resulting fatigue life was performed to fit regressions to predict the fatigue performance of each mixture. Differences in fatigue performance due to field and laboratory production and compaction methods were investigated. Also, in-situ mixtures were compared to mixtures produced accurately from the job mix formula to determine if changes occurring between the laboratory and batch plant significantly affected fatigue life. Results from the fatigue evaluation allowed verification of several hypotheses related to mixture production and compaction and fatigue performance. It was determined that location within the pavement surface, such as inner or outer wheelpath or center-of-lane, did not significantly affect laboratory fatigue test results, although the location will have significant effects on in-situ fatigue life. Also the orientation of samples cut from an in-situ pavement (parallel or perpendicular to the direction of traffic) had only a minor effect on the laboratory fatigue life, because the variability inherent in the pavement due to material variability is greater than the variability induced by compaction. Fatigue life of laboratory-compacted samples was found to be greater than fatigue life of field-compacted samples; additionally, the variability of the laboratory compacted mixture was found to be less than that of the field-compacted samples. However, it was also found that batch-plant production significantly reduces specimen variability as compared to small-batch laboratory production when the same laboratory compaction is used on both specimen sets. Finally, for Smart Road mixtures produced according to the job mix formula, the use of polymer-modified binder or stone matrix asphalt was shown to increase the expected fatigue life. However, results for all mixes indicated that fatigue resistance rankings might c

This project reviewed existing laboratory methods for accurately describing the constitutive behavior of the mixes used in the Commonwealth of Virginia. Indirect tensile (IDT) strength, resilient modulus, static creep in the IDT and uniaxial modes, flexural beam fatigue, and dynamic modulus tests were conducted on two typical mixes used in Virginia: SM-9.5A (surface mix) and BM-25.0 (base mix). The tests conducted produced a wealth of data on typical values for the properties of the two mixes studied over a wide range of temperatures and loading frequencies. The results suggest that the IDT strength test is an effective test to characterize the tensile strength of hot-mix asphalt (HMA), especially for thermal cracking evaluation. The resilient modulus test and the static creep test in the IDT setup are practical and simple to perform, but the analysis of the measurements is complicated, and the variability of the results is high. The compressive uniaxial dynamic modulus and the uniaxial static creep tests were found to be simple to conduct and to analyze because of the homogeneous state of stress in the specimen during testing. The flexural fatigue test was time consuming, but the test produces valuable information about the fatigue properties of hot-mix asphalt. The investigation also found good correlations among the IDT strength, resilient modulus, and dynamic modulus results. A variety of tests is recommended for characterizing the mechanistic-empirical pavement analysis and design. These tests would provide the properties needed to characterize the asphalt layers for the pavement analysis and design. The recommended tests are as follows: IDT strength for characterizing HMA susceptibility to thermal cracking, dynamic modulus for characterization of the constitutive behavior of the HMA, uniaxial creep for characterizing permanent deformation characteristics, and flexural fatigue tests to characterize fatigue properties. Materials characterization testing can be a

This study evaluated 18 pavement sections located in high-traffic highways in Virginia to find a premium pavement design with a life span of 40 years or more using current and past field experience. The selected pavement sections were thought to perform well. Eight flexible pavements, six composite pavements, two continuously reinforced concrete pavements, and two jointed plain concrete pavements were investigated. Field testing consisted of (1) falling weight deflectometer (FWD) testing to assess the structural capacity of the different pavements and to backcalculate the pavement layer materials' moduli, (2) ground-penetrating radar (GPR) scanning to determine layer thicknesses and to locate any abnormalities inside the pavements, (3) digital imaging to determine condition indices, (4) longitudinal profile measurements to calculate International Roughness Index, and (5) coring and boring to perform material characterization of pavement layers. Hot mix asphalt tests included resilient modulus and creep compliance. Concrete was tested for compressive strength. The analysis of the collected data suggests that premium pavement designs can be obtained. The field investigations suggest that all the tested sites are performing satisfactorily and show very low structural distress. Limited material-related problems were found at some sites, which induced non-load related distresses. It was also confirmed that FWD, GPR, and digital imaging are very useful tools to assess the condition of existing pavements. Since the three categories of pavements (flexible, composite, and rigid) were found to perform well, the study recommends that evaluation of other pavement sections, which are thought to perform in a less than optimal state, be conducted to define the causes of the less than desired performance. The selection of the most appropriate premium pavement design should be based on a detailed life-cycle cost analysis; hence, such analysis should be performed. Mechanistic empiric

This project reviewed existing laboratory methods for accurately describing the constitutive behavior of the mixes used in the Commonwealth of Virginia. Indirect tensile (IDT) strength, resilient modulus, static creep in the IDT and uniaxial modes, flexural beam fatigue, and dynamic modulus tests were conducted on two typical mixes used in Virginia: SM-9.5A (surface mix) and BM-25.0 (base mix). The tests conducted produced a wealth of data on typical values for the properties of the two mixes studied over a wide range of temperatures and loading frequencies. The results suggest that the IDT strength test is an effective test to characterize the tensile strength of hot-mix asphalt (HMA), especially for thermal cracking evaluation. The resilient modulus test and the static creep test in the IDT setup are practical and simple to perform, but the analysis of the measurements is complicated, and the variability of the results is high. The compressive uniaxial dynamic modulus and the uniaxial static creep tests were found to be simple to conduct and to analyze because of the homogeneous state of stress in the specimen during testing. The flexural fatigue test was time consuming, but the test produces valuable information about the fatigue properties of hot-mix asphalt. The investigation also found good correlations among the IDT strength, resilient modulus, and dynamic modulus results. A variety of tests is recommended for characterizing the mechanistic-empirical pavement analysis and design. These tests would provide the properties needed to characterize the asphalt layers for the pavement analysis and design. The recommended tests are as follows: IDT strength for characterizing HMA susceptibility to thermal cracking, dynamic modulus for characterization of the constitutive behavior of the HMA, uniaxial creep for characterizing permanent deformation characteristics, and flexural fatigue tests to characterize fatigue properties. Materials characterization testing can be a

A ground-penetrating radar (GPR) system was used to collect data over the different pavement sections of the Virginia Smart Road from June 1999 until December 2002. Three antennae at different frequencies were used for this research. The collected data were successfully used to evaluate the physical GPR detection limitations, to evaluate the GPR accuracy for pavement layer thickness determination, to control the installation of three different types of reinforcing meshes installed within the pavement, and to estimate the in-situ complex dielectric constant of several types of hot-mix asphalt (HMA). The data analysis results were verified by the well-documented structure and composition of each section of the road, in addition to the embedment of 35 copper plates (perfect electromagnetic reflectors) at the different layer interfaces during construction of the pavement. It was found that GPR is a feasible nondestructive tool to estimate the layer thicknesses of bound and unbound aggregate layers, HMA layers, and concrete slabs. However, interface detection can be altered if the layers have comparable dielectric constants. A technique was developed to estimate the frequency-dependent in-situ complex dielectric constant of HMA materials. Results have shown that the effect of the variations of the dielectric properties within the GPR bandwidth is insignificant vis-a-vis the accuracy of thickness estimation. The use of GPR as a quality control tool to verify the success of steel reinforcing mesh installation was also found to be feasible. Given the success of using GPR for the aforementioned applications in the Virginia Smart Road, it is recommended that the Virginia Department of Transportation use GPR more frequently as a quality control tool during new pavement construction projects and as an assessment tool prior to project rehabilitation and as part of Virginia's pavement management system.

R27-SP56, The use of reclaimed asphalt pavement (RAP) has economic and environmental impacts. This report investigates the prospective use of RAP in preservation treatments (mainly chip sealing and microsurfacing) in Illinois. A review of the current state of knowledge and practice was conducted. The economic and logistic feasibility of using RAP in preservation treatments in Illinois were investigated. Data were collected on RAP availability in the state followed by a survey distributed to district engineers and highway construction contractors. The survey asked about the availability of RAP, its viability in preservation treatments, and the readiness for its application. A unit price analysis was conducted to assess the financial viability of using RAP compared to virgin aggregate. The results suggested there was an excess of good quality and fractionated RAP, and contractors are open to using RAP in various applications. Considering contract unit prices in Illinois, no significant difference would be expected when RAP is used in place of virgin aggregate. Hence, using RAP in preservation treatments would probably make preservation treatments more viable. Economic and environmental analyses demonstrated that using RAP in preservation treatments would reduce the impact on the environment by reducing energy, global warming potential, and greenhouse gases while providing cost savings. A simple decision tool was developed to provide guidance on using RAP in preservation treatments.

R27-231, The Federal Aviation Administration (FAA) advisory circular AC 150/5100-13 authorized the use of state highway material specifications at nonprimary public-use airports serving aircraft less than 60,000 pounds gross weight. This approval is based on the condition that the safety and life span of these airports will not be adversely affected. The use of highway materials provides the Illinois Department of Transportation (IDOT) with benefits, including cost, expertise, material availability, and sustainability. This study investigated the feasibility of using highway mixes for nonprimary airport pavements. Three classes of mixes were evaluated—namely, IDOT highway mixes, IDOT state airport mixes, and FAA airport mixes. The matrix consisted of 18 mixes: 15 surface and 3 binder mixes. The 15 surface mixes comprised seven laboratory-designed (five highway, two airport) and eight plant-produced mixes (four highway, four airport). All binder mixes were airport mixes and had the same composition and mix design parameters as highway mixes. Mixture performance was evaluated using the Hamburg wheel-tracking test (HWTT) to evaluate rut potential, the Illinois flexibility index test (I-FIT) to assess cracking potential, and the tensile strength ratio (TSR) test to evaluate moisture susceptibility. Performance testing was performed at both air voids of 4% and 7% corresponding to the initial in-place densities of nonprimary airports and highways, respectively. From the HWTT results, highway mixes had lower rut potential than airports mixes. With respect to the TSR test, airport mixes had lower tensile strengths than highway mixes. However, the TSR values (ratio of conditioned to unconditioned tensile strength) were similar for highway and airports mixes. The I-FIT results demonstrated comparable results between highway and airport mixes. Airport mixes had higher and comparable flexibility index for laboratory and plant mixes, respectively. By leveraging highway construction mater

R27-204, Researchers conducted eight large-scale laboratory tests to assess the combined impact of hot-mix asphalt (HMA) overlay mix and thickness on its performance to control reflective cracking. Bonding efficiency, flexibility, and stiffness of the HMA mix as well as overlay thickness significantly affect an overlay’s performance against reflective cracking. Researchers developed a generalized 3D finite-element model to predict an overlay’s reflective cracking potential and generated a database of 128 cases. They also developed a data-driven surrogate model to predict reflective cracking potential that engineers can easily use. Life-cycle cost analysis of overlay alternatives was performed using Illinois Department of Transportation’s unit prices from contracts between 2018 and 2019. The researchers identified optimal overlay configurations to control reflective cracking. An overlay composed of a 1.5 in (38.1 mm) SMA-9.5 or 1.25 in (31.8 mm) IL-9.5FG surface course and a 0.75 in (19.1 mm) IL-4.75 binder course had the lowest annual cost per mile among non-interstate projects. For interstate projects, an overlay composed of a 2 in (50.8 mm) SMA-12.5 surface course and a 2.25 in (57.2 mm) IL-19.0 binder course was the most cost-effective. The study concluded that to control reflective cracking and to reduce life-cycle cost, an overlay composed of an SMA-9.5 surface course and an IL-4.75 binder course is recommended for non-interstate projects. An IL-9.5FG surface course and an IL-4.75 binder course are suggested for low-volume and low-speed roads. For interstate projects, an overlay comprised of an SMA-12.5 surface course and an IL-19.0 binder course is recommended. A data-driven surrogate model may be used to design overlay thicknesses.

R27-228, Connected, automated, shared, and electric (CASE) technologies have invoked Mobility 4.0—a connected, digitized, multimodal, and autonomous system of systems. This project established a flexible and adaptable blueprint that would streamline multidisciplinary and multistakeholder efforts as well as leverage available resources to prepare the Illinois Department of Transportation and other transportation agencies. Illinois has several strengths that make it an attractive location for CASE technology companies, including a talent pool from top-ranked universities, well-developed transportation infrastructure, government support, and a robust ecosystem of collaboration and innovation. Illinois also faces potential challenges (e.g., competition from other states and countries, limited access to funding, regulatory hurdles, and infrastructure readiness for new mobility technologies). Seven smart mobility pillars were identified in this study for Illinois—namely, connected and automated (CA) freight, scaling intelligent transportation systems, farm automation, insurance, urban mobility, CA logistics, and alternative fuels. The balanced scorecard ranked the pillars as follows (from highest): alternative fuels, scaling intelligent transportation systems, CA freight, farm automation, CA logistics, insurance, and urban mobility. Tactical focus areas were also identified per pillar and were prioritized with suggested leads and stakeholders to champion the CASE directives and opportunities. Near-term actions for Illinois were also suggested that included establishing a central structure for Illinois’ CASE program, enriching the knowledge base and experience, preparing transportation infrastructure, partnerships with external stakeholders, and expansion of laws, regulations, and policies that will help administer and grow CASE technology deployment and integration.

69A3551747105, Truck platoons are expected to improve safety and reduce fuel consumption. However, their use is projected to accelerate pavement damage due to channelized-load application (lack of wander) and potentially reduced duration between truck-loading applications (reduced rest period). The effect of wander on pavement damage is well documented, while relatively few studies are available on the effect of rest period on pavement permanent deformation. Therefore, the main objective of this study was to quantify the impact of rest period theoretically, using a numerical method, and experimentally, using laboratory testing. A 3-D finite-element (FE) pavement model was developed and run to quantify the effect of rest period. Strain recovery and accumulation were predicted by fitting Gaussian mixture models to the strain values computed from the FE model. The effect of rest period was found to be insignificant for truck spacing greater than 10 ft. An experimental program was conducted, and several asphalt concrete (AC) mixes were considered at various stress levels, temperatures, and rest periods. Test results showed that AC deformation increased with rest period, irrespective of AC-mix type, stress level, and/or temperature. This observation was attributed to a well-documented hardening–relaxation mechanism, which occurs during AC plastic deformation. Hence, experimental and FE-model results are conflicting due to modeling AC as a viscoelastic and the difference in the loading mechanism. A shift model was developed by extending the time–temperature superposition concept to incorporate rest period, using the experimental data. The shift factors were used to compute the equivalent number of cycles for various platoon scenarios (truck spacings or rest period). The shift model was implemented in AASHTOware pavement mechanic–empirical design (PMED) guidelines for the calculation of rutting using equivalent number of cycles.

Due to the large percentage of goods moved by commercial trucks and its ever-growing freight industry, the U.S. needs innovative technologies to improve the efficiency of trucking operations and ensure continuous growth of the economy. One example of such a technology is the introduction of wide-base single tires to replace conventional dual tire systems. After more than two decades of research powered mainly by the tire industry, a new generation of wide-base tire was recently introduced. Compared to the first generation of wide-base tires, these new tires offer safety and cost-savings characteristics. Despite the significant advancements achieved through previous research projects on the impcat of wide-base tires on pavements, past investigations have not evaluated the damage wide-base tires cause to low-volume secondary roads. This pavement class is widely encountered in many trucking applications, although for short distances, but the impact of the new generation of wide-base tires on these pavement structures is unclear. In addition, the static uniform loading assumption used in conventional flexible pavement design methods is inconsistent with realistic tire loading conditions and may result in erroneous pavement response and damage predictions. To address these shortcomings, this research project uses a developed three-dimensional (3-D) finite element model to predict pavement responses to loading applied by various tire configurations on secondary road pavements. This model incorporates the measured 3-D tire-pavement contact stresses, hot-mix asphalt (HMA) linear viscoelasticity, continuous moving load, and utilizes implicit dynamic analysis. The impact of wide-base tires on secondary road pavement damage was analyzed using available damage models, and the results were compared to the damage from conventional dual-tire assemblies.

R27-152, Permits are one of the most effective and common tools for state agencies to regulate the operation of overweight and, oversize vehicles by ensuring the safety of passenger and freight traffic and minimizing damage to pavements and, bridges while promoting commerce and the safe movement of goods and services. Although the State of Illinois uses a, relatively comprehensive permit system, many of its parts have not been revised for more than 30 years. Therefore, the, objective of this study was to revise the current permit system by evaluating up-to-date impacts of overweight vehicles., In this study, impacts of overweight (OW) vehicles were evaluated in three aspects (bridge, pavement, and traffic safety), and individual fees were developed for each. The most recent databases on infrastructure condition and state-of-the-art, prediction/classification algorithms were employed to produce the realistic and up-to-date assessment of OW vehicles', impact. Finally, a combined permit fee was recommended as a function of miles to be traveled, as well as axle and, weight information, by aggregating the calculated individual fees.

Laboratory fatigue testing was performed on six Superpave HMA mixtures in use at the Virginia Smart Road. Evaluation of the applied strain and resulting fatigue life was performed to fit regressions to predict the fatigue performance of each mixture. Differences in fatigue performance due to field and laboratory production and compaction methods were investigated. Also, in-situ mixtures were compared to mixtures produced accurately from the job mix formula to determine if changes occurring between the laboratory and batch plant significantly affected fatigue life. Results from the fatigue evaluation allowed verification of several hypotheses related to mixture production and compaction and fatigue performance. It was determined that location within the pavement surface, such as inner or outer wheelpath or center-of-lane, did not significantly affect laboratory fatigue test results, although the location will have significant effects on in-situ fatigue life. Also the orientation of samples cut from an in-situ pavement (parallel or perpendicular to the direction of traffic) had only a minor effect on the laboratory fatigue life, because the variability inherent in the pavement due to material variability is greater than the variability induced by compaction. Fatigue life of laboratory-compacted samples was found to be greater than fatigue life of field-compacted samples; additionally, the variability of the laboratory compacted mixture was found to be less than that of the field-compacted samples. However, it was also found that batch-plant production significantly reduces specimen variability as compared to small-batch laboratory production when the same laboratory compaction is used on both specimen sets. Finally, for Smart Road mixtures produced according to the job mix formula, the use of polymer-modified binder or stone matrix asphalt was shown to increase the expected fatigue life. However, results for all mixes indicated that fatigue resistance rankings might c

Interface bonding between hot-mix asphalt (HMA) overlays and Portland cement concrete (PCC) pavements can be one of the most, significant factors affecting overlay service life. Various factors may affect the bonding condition at the interface, including HMA material, tack coat material, tack coat application rate, PCC surface texture, temperature, and moisture conditions. The objective of this study is to, quantify the impact of these parameters on the permanent deformation of the HMA overlay. This study includes three major components, to achieve the objective: laboratory testing, numerical modeling, and accelerated pavement testing. This report presents and analyzes the, laboratory testing results., A direct shear test device was built and utilized to investigate the characteristics of the HMA-PCC interface and to determine the, interface shear strength in the lab. Tests were run in monotonic mode at a constant loading rate of 0.47 in/min (12 mm/min). Test, specimens were prepared using field PCC cores, laboratory prepared HMA, and tack coat materials provided by the supplier. Parameters, affecting the interface performance that were evaluated include HMA material type (SM-9.5 surface mix and IM-19.5A binder mix), tack, coat type (SS-1h and SS-1hP emulsions, and RC-70 cutback), tack coat application rate, PCC surface texture, temperature, and, moisture conditions. Test results showed that the asphalt emulsions SS-1h and SS-1hP produced greater interface bonding strength than, the cutback asphalt RC-70. The SM-9.5 surface mix was found to have better interface strength than the IM-19.0A binder mix., The HMA tested produced the same trend of interface shear strength with tack coat application rate for various tack coat types. The, optimum residual tack coat application rate for the SS-1hP emulsion using IM-19.0A binder mix was 0.04 gal/yd2 (0.18 L/m2) in the lab., The direction of tining on the PCC produced no effect on interface shear strength at 20 oC. However, the milled concrete surface, provided greater interface shear strength than both tined and smooth PCC surfaces for the same tack coat application rate. At the, optimum tack coat application rate, the smooth PCC surface produced higher interface shear strength than the tined surface. As, temperature increased, interface bonding strength decreased. Moisture conditioning significantly decreased the interface shear strength., This reduction was more pronounced when a stripping-vulnerable binder mix IM-19.0B was used.

Interface bonding between hot-mix asphalt (HMA) overlays and Portland cement concrete (PCC) pavements is one, of the most significant factors affecting overlay service life. This study was performed to quantify the effects of HMA type, tack coat type, tack coat application rate, and PCC surface texture on the interface bonding and overlay performance, through laboratory testing, accelerated pavement testing (APT), and numerical modeling. This report presents the, outcomes of the APT, as well as the numerical modeling of pavement interfaces. The results of the laboratory testing are, covered in a companion report., The APT built on and validated previously completed laboratory tests where an HMA overlay was placed on top of, an existing PCC pavement having various surface textures including smooth, transverse tined, longitudinal tined, and, milled. In addition, zebra sections were included to evaluate the effect of non-uniform tack coat application. Asphalt, emulsion SS-1hP and cutback asphalt RC-70 were applied at three residual application rates, 0.02, 0.04, and 0.09 gal/yd2, (0.09, 0.18, and 0.41 L/m2); asphalt binder PG64-22 was applied at 0.04 gal/yd2 (0.41 L/m2). Two HMA designs, standard, binder mix and moisture sensitive binder mix, were used along with the three tack coats. Twenty-five pavement test, sections were constructed and loaded with the Accelerated Transportation Loading ASsembly (ATLAS) at the centerline., The tensile strains at the bottom of HMA, to quantify potential interface slippage, were measured for selective sections, and, primary HMA rutting was analyzed for all sections. The APT results validated laboratory determined optimum tack coat, application rate, which provided the lowest interface strain and surface rutting in the field. Both PG64-22 and SS-1hP, showed better rutting resistance than RC-70. Milled PCC surface provided lower rutting than transverse-tined and smooth, surfaces. The field testing also showed that PCC cleaning methods play an important role in the HMA-PCC bonding. Higher, rutting depth was measured in sections with uneven tack coat distribution compared to that with uniform tack coat, distribution. Field testing results don’t show enough evidence to prove that using a moisture-sensitive mix will result in, higher HMA surface rutting.

ICT-R27-11, For current recycled mix designs, the Illinois Department of Transportation (IDOT) assumes 100% contribution of, working binder from Recycled Asphalt Pavement (RAP) materials when added to Hot Mix Asphalt (HMA). However, it is, unclear if this assumption is correct and whether some binder may potentially be acting as “black rock,” and not, participating in the blending process with the new binder. Furthermore, it is also unclear whether binder modifications, should be considered in the mix design for recycled HMA. The goal of this research was to determine if the current IDOT, mix design practice required modification with respect to the use of RAP., A set of mixtures was prepared using RAP in accordance with current practice. Additional sets were prepared, using recovered binder and recovered aggregate to simulate the effect of RAP binder blending with virgin binder. Mixes, containing 0, 20, and 40%RAP were prepared and the dynamic modulus testing results of these mixtures were compared to, illustrate the effect of RAP on HMA. Tests on recovered, virgin, and blended binders were also conducted using the, Dynamic Shear rheometer (DSR)., This study found that up to 20% RAP in HMA does not require a change in binder grade. However, at 40% RAP in, HMA, a binder grade bump at high temperature and possibly at low temperature is needed; more tests are required to verify, the need for low temperature binder grade bumping. In addition, this study recommends RAP fractionation in the, preparation of laboratory specimens.

VTRC Project # 67775, TPF-5(045), Crack sealing has been widely used as a routine preventative maintenance practice. Given its proper, installation, crack sealants can extend pavement service life by three to five years. However, current, specifications for the selection of crack sealants correlate poorly with field performance. The purpose of this, research was to develop performance guidelines for the selection of hot-poured bituminous crack sealants at, low temperature. This was accomplished by measuring the mechanical properties of crack sealant at low, temperature and then developing performance criteria for material selection. The modified direct tension test, (DTT), crack sealant direct tension test (CSDTT), simulates the in-situ loading behavior of crack sealants in the, laboratory. A modified dog-bone specimen geometry, which allows specimens to be stretched up to 95%, is, recommended. This new specimen geometry also facilitates sample preparation. Tensile force is applied to the, dog-bone specimen, with its effective gauge length of 20.3mm, and is pulled at a deformation rate of, 1.2mm/min. Fifteen sealants were tested at various temperatures, and three performance parameters are, suggested as indicators of sealant performance: extendibility, percent modulus reduction, and strain energy, density. Extendibility, which is used to assess the degree of deformation undergone by a sealant at low, temperature before it ruptures or internal damage is observed, is recommended as a measured parameter to be, included in the performance-based guidelines for the selection of hot-poured crack sealants. Extendibility, thresholds were defined as function of low service temperatures. The CSDT is conducted at +6oC above the, lowest in service temperature because of the relatively high test loading rate compared to in-situ crack sealant, movement rate.

VTRC Project # 67775, TPF-5(045), Crack sealing has been widely used as a routine preventative maintenance practice. Given its proper installation, crack sealants can extend, pavement service life by three to five years. However, current specifications for the selection of crack sealants correlate poorly with field, performance. The purpose of this research was to develop performance guidelines for the selection of hot-poured bituminous crack sealants at, low temperature. In this part of the research, the creep behavior of crack sealant at low temperature is measured and performance criteria for, material selection were developed. Because various pavement and State agencies are well acquainted with and own the Bending Beam, Rheometer (BBR), which was developed during the Strategic Highway Research Program (SHRP), an attempt was made to utilize the same, setup to test hot-poured bituminous-based crack sealants. Testing conducted in this research project indicated that the standard BBR was, inappropriate for testing soft bituminous-based hot-poured crack sealant, even at -40°C. The measured deflection exceeded the BBR limit, for, some sealants, after only a few seconds of loading. To address this issue, the moment of inertia of the tested beam was increased by doubling, its thickness (from 6.35mm to 12.7mm). For the new beam dimensions, it was found that only 4% of the beam center deflection is due to shear, a, value deemed acceptable for sealant evaluation and comparison., In an effort towards developing a robust testing procedure, 15 sealants from various manufacturers were included in the study and tested, between –4°C and –40°C. In addition, five sealants, which have known field performance, were tested to validate the laboratory results and, establish specification thresholds for the selection guidelines. Since stiffness calculation in the BBR test method requires that measurements be, made within the linear region of viscoelastic behavior, validation of this theory was conducted for crack sealants. This was found to be generally, the case with crack sealants, which allowed for the use of the time-temperature superposition. If the temperature-superposition principle is, applied, the stiffness at 240s at a given temperature can be used to predict the stiffness after 5hr of loading at a temperature that is 6°C lower., With the assumption of linear viscoelastic behavior, sealants performance can be characterized through stiffness, average creep rate, and, dissipated energy ratio. Stiffness was found to be sensitive to temperature changes and could be used to differentiate between sealants. The, measurements of the average creep rate and the dissipated energy ratio were also found to be valuable in differentiating between sealants. In, addition, numerical modeling was used to simulate the mechanical response of crack sealants at low temperatures. Parameters that may be, used for evaluating crack sealant cohesive performance using the crack sealant BBR (CSBBR) are the stiffness at 240s, average creep rate, and, the dissipated energy ratio. For simplicity, the first two parameters, stiffness at 240s and average creep rate, are recommended for, implementation in the sealant performance grade. The recommended thresholds are maximum stiffness of 25MPa and minimum average creep, rate of 0.31.

VTRC Project # 67775, TPF-5(045), Current crack sealant specifications focuses on utilizing simple empirical tests such as penetration, resilience, flow, and bonding to cement concrete briquettes (ASTM D3405) to measure the ability of the material, to resist cohesive and adhesion failures. There is, however, no indication of the pertinence of these standard, tests to predict the success of field installation and sealant performance. In an effort to bridge the gap between, sealant fundamental properties and field performance, performance-based guidelines for selection of hot-poured, crack sealants are currently being developed. This report focuses on the development of the apparent viscosity, test method. This test uses a modified version of the Brookfield rotational viscometer. Based on the results of, this study, the measured apparent viscosity of hot-poured crack sealant using SC4-27 spindle at 60rpm (20.4s-1), at the recommended installation temperature was determined to be reasonably representative of sealant, viscosity at shear rates resembling field application. To ensure measurement consistency and stability, a 20min, melting time and a 30-s waiting time prior to data collection are recommended. To establish precision and bias, for the test, a round robin testing was conducted among seven laboratories. Average coefficient of variation, within and between laboratories was found to be 2% and 6%, respectively. Using the data from the round robin, testing, and based on ASTM precision and bias standard (ASTM practices C802 and C670), maximum, permissible differences within a laboratory and between laboratories were found to be 4.6% and 16.9%., Considering the high polymer or crumb rubber content in crack sealants and sealant temperature sensitivity, the, repeatability and reproducibility of the developed test is within an acceptable range. These values are, comparable to those of asphalt binder: 3.5% and 14.5% based on ASTM D4402-02 and 3.5% and 12.1% based, on AASHTO 2006 T316.

98160, This report summarizes a comprehensive research effort to validate thresholds for performance-based guidelines and, grading system for hot-poured asphalt crack sealants. A series of performance tests were established in earlier research and, include the crack sealant bending beam rheometer (CSBBR), crack sealant direct tension test (CSDTT), the crack sealant, adhesion test (CSAT), a rotational viscosity test, and a dynamic shear test. Validation was accomplished through an extensive, field performance study incorporating a wide spectrum of commonly used sealants installed in eight test sites around the United, States using two basic treatment methods: (1) clean and seal, and (2) rout and seal. Performance of these sealants and treatment, methods were monitored for 3 years to quantify relative performance, primarily through adhesive and cohesive failures, as well, as overband wear. Field samples were also collected from the sites to conduct laboratory testing to reflect in-service properties., A statistical method was used to develop correlations of the tests parameters with the field performance. The composite score, approach, combining ranking and correlation, was used to develop a quantitative scale for determining the level of acceptance., Based on the composite score, a strong or acceptable correlation was obtained between field performance and laboratory test, parameters. After the correlation between field performance and lab results was confirmed, the thresholds for test methods were, selected or fine-tuned., An investigation was also conducted to evaluate the short-term and long-term aging effects of hot-poured crack sealants, through a differential aging test. Rheological and mechanical properties of sealants at different aging stages were monitored to, characterize the aging effects. Laboratory aging of sealants was studied using three different aging methods: kettle aging, melter, aging, and vacuum oven aging (VOA). The aging index was used to evaluate the effect of these aging methods. By a, comparison of the stiffness master curves obtained from the CSBBR test for field-aged samples and laboratory-aged samples, VOA was validated as a reasonable aging method for simulating 2 to 5 years of field aging., The research proposes new guidelines for full implementation as AASHTO specifications. In addition to validated and, revised thresholds for existing protocols, the research proposed a modified adhesion test and a simplified test for tracking, resistance. Close inspection of the installation techniques and early performance feedback also supported the development of, guidelines for crack sealant installation and application.