Emerging Technologies for Material, Design, Rehabilitation, and Inspection of Roadway Pavements

In this study, the objective was to conduct a laboratory investigation of rheological properties of non-foaming WMA additives at a mid-temperature. The conventional testing procedures such as viscosity, performance grade, creep and creep recovery, and frequency sweep were performed to determine the influences of non-foaming additives on asphalt binders. The experimental design included four binders and four non-foaming WMA additives. The test results indicated that, as expected, the non-foaming WMA additive can reduce the viscosity value of asphalt binder and thus decrease the mixing and compaction temperatures of mixture. The failure temperature of binders containing non-foam additive has a slight increase compared to the virgin binder and thus, improve the rut resistance of the mixtures. In addition, creep recovery and frequency sweep tests show that the binder with Sasobit has a slightly higher complex modulus but exhibits lower creep compliance and phase angle than the binder containing other WMA additives.

Benefits of warm mix asphalt (WMA) technologies in terms of energy savings and air quality improvements are highly promising. However, further investigations are needed to validate their performance as rheological and viscoelastic data are significantly lacking for material conditions in Oklahoma. To this end, effects of dosage levels of a WMA additive, Advera®, on the performance grade (PG) of a local PG 64-22 binder were evaluated. The effectiveness of a liquid anti-stripping (AS) agent, AD-here® HP Plus, on the WMA-modified binder was also studied. Based on the binder test data, the optimum dosage of Advera® was found to be 6% (by the weight of the binder), which did not alter the PG grade of the base binder. The liquid AS agent was found to be effective in increasing the fatigue fracture resistance of the WMA-modified binder. The current study is expected to enhance the inventory of rheological database and help in implementing WMA mixes in Oklahoma.

As a result of the 1997 Kyoto treaty on climate changes, many countries n the world were faced with greenhouse gas reduction targets. Warm-mix asphalt (WMA) technologies are currently of interest to road construction industry around the world. WMA technology was developed in Europe and introduced into the United States in 2002. WMA technologies can decrease the energy consumption and emissions associated with conventional hot-mix asphalt (HMA) production. Based on those benefits and increasing awareness of WMA, the Korea Institute of Construction and Technology (KICT) developed WMA technology in Korea. WMA developed by KICT used a WMA additive that was developed by Korea Kumho Petrochemical Co. LTD. To evaluate the performance of WMA developed in Korea, an experimental test program was designed to evaluate rutting and crack resistance by using thewheel track test and indirect tensile strength test as a function of mixture types. In the case of rutting resistance, WMA shows better performance than HMA at high temperature. The Indirect Tensile Strength (IDT) test results of both WMA and HMA were same.

As a means to optimize construction costs and in adherence to the Green Revolution, many highway agencies are actively exploring the use of Warm Mix Asphalt (WMA) technology and recycled materials. Based on the Evotherm® WMA and hot-asphalt recycled technology, the feasible application of recycled WMA with Reclaimed Asphalt Pavement (RAP) materials was investigated. In this study various laboratory tests such as Marshall Stability and moisture susceptibility were conducted to evaluate the effects of different RAP contents. The performances that include dynamic stability of WMA with a certain proportion of RAP can be improved. WMA technology can accommodate a higher percentage of RAP than hot recycled technology.

The major cause of failure of pavements on orthotropic steel bridge decks has been fatigue cracking of the pavement over the points of attachment of the webs of the longitudinal stiffeners to the steel deck plate. Accelerated constant load fatigue tests on composite (deck plate and pavement) flexural fatigue beams have been used to compare pavement systems and to predict service life. However, accelerating the tests to provide useful information in a reasonable time frame requires that the load frequency or load level, or both, be substantially increased beyond service conditions. If the load is increased too much, permanent distortion of the specimen may result, thus making the test no longer a fatigue test. Increasing load frequency too much may overheat the test specimen. Since pavement stiffness decreases as its temperature increases the temperature increase reduces the stresses that cause the fatigue cracks. This paper discuses these potential problems and presents test results to help define the limitations of accelerated fatigue tests for orthotropic steel deck pavements.

The CSIR Built-Environment, in conjunction with the University of Pretoria in South Africa developed a low cost option for the upgrading of unsurfaced roads. The proposed solution is a thin layer of normal concrete reinforced with 5.6mm diameter steel with a mesh grid size of 200mm. This thin layer is placed on top of the existing unsurfaced road with minimal preparation to the existing road surface using labour-intensive construction methods. In order to determine the structural capacity of this type of overlay, full-scale Heavy Vehicle Simulator (HVS) tests were conducted. This paper summarizes the results from the accelerated pavement testing (APT) tests and is aimed at building confidence in the use of Ultra Thin-layer Reinforced Concrete Pavement (UTRCP), with cognizance being taken of the pavement structure, support conditions, construction, climate and traffic. APT testing has shown that this pavement type has exceptionally good performance if used on low volume roads such as residential streets but is sensitive to water damage. The UTRCP layer does not act as a proper structural layer and the importance of a well-constructed impervious base layer is highlighted in this study.

Concrete Pavement Preservation (CPP) is a series of engineered techniques developed over the past 40 years to manage the rate of pavement deterioration in concrete streets, highways and airports. CPP is a non-overlay option used to repair areas of distress in concrete pavement without changing its grade. This rational, preventive procedure restores the pavement to a condition close to or better than original and reduces the need for major and more costly repairs later. Due to the growing popularity of CPP, an increasing number of research projects focused on the application and benefits of CPP have been initiated and completed during the past decade. The focus of this paper is engineering application related to CPP with an emphasis on dowel bar retrofit and diamond grinding. The paper is presented in three sections. The first outlines the available treatments used for concrete pavement preservation. The second section is focused on current research related to these treatments and highlights the benefits and lessons learned while applying these treatments over the past 40 years. The final section discusses the environmental benefits of CPP and its role in today's environmentally responsible and sustainable transportation marketplace.

The paper discusses the use of the Impact Echo Scanning nondestructive evaluation (NDE) technique for quality assurance and condition assessment of the grouting of post-tensioned bridge ducts and concrete bridge decks. Both research and case history results are presented. Impact Echo Scanning was first done for detecting void/grout conditions in post-tensioned ducts. Recent research and development of a Bridge Deck Scanner using the Impact Echo Scanning technique is compared with Ground Penetrating Radar and Acoustic Chain Drag Sounding to identify concrete delaminations due to rebar corrosion. The research on both Impact Echo Scanning applications was sponsored by the US National Cooperative Highway Research Innovations Deserving Exploratory Analysis program. The use of the Bridge Deck Scanner to evaluate concrete deck conditions in terms of void/honeycomb and thickness is also discussed.

The reinforcing agent for the fly ash (JNS-2 Model) from San Xin Construction and Technology Corporation in Zhenjiang City was used to stabilize the fly ash. Then series of tests on the road performance of JNS-2 stabilizing fly ash were conducted systematically. First, tests about the optimal proportion of stabilizing fly ash were carried out, then the road performance tests including the unconfined compressive strength, indirect tensile strength, frost stability, drying shrinkage, temperature shrinkage, fatigue strength were conducted for JNS-2 stabilizing fly ash; at the same time, its test results were compared to those of lime fly ash gravel and lime fly ash macadam to determine its control parameters of road performance. The results from the experimental investigation showed that JNS-2 stabilizing fly ash had higher strength and resilience modulus, better frost stability and anti-fatigue performance and lower shrinkage. The research indicates that JNS-2 stabilizing fly ash has potential to be used as a pavement base layer material in similar applications and can be used as a sub-base material in highway pavements.

In order to reduce the economic loss of discarded or improved reclamation with high liquid limit soil, the fundamental characteristics of high liquid limit soil is studied through the lab tests, and aim at different type of high liquid limit soil, the engineering characteristics of direct reclamation and the best improved schemes are researched based on the trial road sections. It is shown that high liquid limit clay and sand-carrying high liquid limit clay can be used directly as embankment, using pack-cover method in accordance with the technical specification in China, and the degree of the compaction can be controlled at 88%, with the filling height no more than 8m and the total height of embankment no more than 12m; high liquid limit silt and sand-carrying high liquid limit silt are not suitable to be filled directly because the (California Bearing Ratio) CBR can not satisfy the requirement of greater than or equal to 3%, and therefore they should be improved before use; high liquid limit silt ought to be improved with quicklime, the best weight percentage is 5%, while sand-carrying high liquid limit silt should be improved with sand, the best weight percentage is 25%.

In France, a large number of sediments which contain various pollutants are dredged each year to maintain navigation in waterways and access to ports. Traditional solutions such as ocean dumping and inland deposit are unsatisfactory, due to the harmful influence on environment. Cement-based treatment used in the pavement as a solution is widely accepted due to its ability to increase the mechanical performance of sediments and to reduce the adverse impact on environment. Therefore, the influence of cement on the geotechnical properties of treated sediments such as Atterberg limits, compaction and strength properties is important to investigate. An identification of physical characteristics of dredged sediments is firstly undertaken. Secondly, cement is mixed with sediments to explore the effect of cement on Atterberg limits. According to the results, it can be found that the liquid limit and plasticity index decreases with cement content, while the plastic limit increases. Finally, different percents of cement are chose to improve the compaction and strength characteristics of sediments, and the potential of treated sediments as a pavement material is evaluated.

Pervious concrete pavement is air and water permeable, the soil underneath can be kept wet and rainwater can quickly filter into ground, allowing groundwater resources to renew in time. Pervious concrete also possesses many other advantages including sound absorption and skid resistance and is therefore suitable for use in Taiwan's rainy and humid environment. However, the prevalence of air voids result in low strength, so pervious concrete has not been suitable for use in surfacing roads with heavy traffic loadings. In this study we sought to determine the suitable mix of cement, silica fume, superplasticizer, steel fiber, course aggregate and so on for a pervious concrete pavement strong enough for road surfacing. The results showed that the compression strength of one pervious concrete core specimen from the simulated field site was up to 275.7kgf/cm² and exceeded the ordinary concrete structure specification. The flexural strength of one pervious concrete sawed specimen from the simulated field site was up to 48.11kgf/cm² and exceeds the highway rigid pavement specification (45 kgf/cm²). Four mixtures were trialed with void contents ranged from 18.8 to 31.9% and densities from 1,890 to 2,034 kg/m³. The field permeability testing method developed for asphalt pavements has been found to work well for pervious concrete. Water penetration was very good with field permeability test showing about 1,100ml/15sec. This study of the simulated field pervious concrete pavement will be valuable for highway design and construction.

Digital Image Processing (DIP) is applied to convert Computerized Tomography (CT) images into digital forms that can be incorporated into finite element modeling. Virtual Indirect Tension Test by taking into account the actual inhomogeneities and microstructures, is used to analysis mechanical behavior of asphalt concrete, with the visco-elastic properties of the sand mastic and elastic properties of the aggregates are inputted into the FEM model. The numerical results show that the material inhomogeneities and voids distributions can have significant effects on the tensile stress distribution along the loading axis of the sample and the coarse aggregates skeleton has greater influence on mechanical properties of asphalt concrete and the proposed method can be extended to predict the mixture behavior based on ingredient properties.

In order to analyze and compare fatigue behaviors of different types of cement stabilized macadam mixture, and thus offer guidance on how to design and select materials for cement stabilized macadam base in practice, the paper carries on compression fatigue test and indirect tensile fatigue test respectively on several cement stabilized macadam mixtures with different cement content and of gradation type. And the unconfined compression strength test follow sequentially when compression fatigue test completed. Results of compression fatigue tests show that the strength of these mixtures has not changes significantly for reasonable cement content and gradation selected. The splitting fatigue test shows that the mixture of a higher content of cement tends to have low mechanical sensitivity and stronger resistance to overloading and Ultra-axle vehicle loading; moreover, the behaviors of fatigue resistance of the cement stabilized macadam mixture would meet the designed requirements on service life so long as its cement content stays around 3.5%. In addition, the splitting fatigue equation proves to be of high accuracy and effectiveness after being reexamined by the different results of the tests.

Quality control (QC) and quality assurance (QA) tests for compaction in construction projects are typically based on density measurements. The main issue regarding density-based QC/QA specifications is that they do not relate to mechanistic properties of materials and modulus that are critical to mechanistic-empirical types of pavement designs (MEPDG). Another concern is that the depth of influence of density measurement is restricted to 300 mm that is insufficient to detect deeper weak spots that are critical during subgrade or subbase compaction. In intelligent compaction (IC) technology the stiffness of the materials can now be identified to provide real-time opportunities to address the above issues and uniformity during compaction of the materials. Intelligent compaction rollers are equipped with roller-integrated measurement systems, global position system (GPS) and on-board displays that provide real time and 100%-coverage evaluation of the materials being compacted. Therefore, IC can bridge the gap between roadway design and roadway performance. Improved pavement engineering leads to the improvement of the design and construction of roadways and extends the life of pavements. This paper provides guidelines for future QC/QA specifications based on extensive IC field validations and knowledge gained from the US FHWA/Transportation Pooled Fund (TPF) IC study. The guidelines will cover all roadway materials from the ground up including subgrade, subbase (including granular and stabilized base), and hot mix asphalt materials. The aspects of the guidelines include: (1) qualifying IC equipment, (2) specifying GPS equipment and requirements, (3) validating IC systems and GPS operations onsite, (4) mapping existing support materials, (5) selecting in-situ tests for calibration, (6) specifying data collection procedures for IC and in-situ tests, and (7) analyzing data and producing reports. All the above come with real world experiences from more than a dozen full scale IC projects. By implementing the IC QC/QA guidelines proposed in this paper, the process of designing and constructing our roadways will lead to the improved performance of roadway systems.

The Rolling Dynamic Deflectometer (RDD) is a nondestructive testing device that is used to evaluate the structural conditions of pavement systems. Unlike discrete deflection measurements such as the Falling Weight Deflectometer and Dynaflect, the RDD provides continuous deflection profiles that enable 100% coverage along the testing lane. The continuous deflection profiles have been used to delineate poorly performing areas to be repaired, develop input for pavement forensic studies, select rehabilitation treatments, and monitor pavement deterioration rates. In this paper, the patterns in RDD deflection data which represent four different structural conditions (with respect to joint load transfer and slab support) in jointed concrete pavements (JCP) are presented and discussed. Then, results from RDD tests used in three project-level studies are presented. The first project involved a continuously reinforced concrete pavement (CRCP) with an asphalt overlay. RDD measurements were used to measure the relative improvement due to the overlay rehabilitation and also monitor the pavement deterioration rate with time. The second project involved a JCP with longitudinal cracking. RDD deflection profiles were used to delineate poorly performing areas due to poor slab-support conditions and identify potential locations of reflective cracking. The third project involved a JCP with faulting. RDD deflection profiles were used to identify locations that needed either dowel-bar retrofit or full-depth repair.

A comprehensive survey and in-depth analysis related to reflective cracking have been conducted at five expressways in Jiangsu province, China. This paper presents analysis results with respect to the main influencing factors of pavement transverse cracking and reflective cracking, revealing the developing mechanism of pavement transverse cracking and reflective cracking. Furthermore, influencing factors and their effects on reflective cracking of semi-rigid base are also proposed in this paper. Several recommendations are presented to effectively prevent reflective cracks.

This study proposes the idea of using robots in pavement inspections and develops a framework for the application of a Pioneer 3-AT (P3-AT) autonomous robot integrated with two types of highly accurate Virtual Reference Station (VRS) technology. The two testing sites constituted in the study were 60 km apart, one of which was a rigid pavement and the other, a flexible pavement. The tire pressure and the horizontal movement of the P3-AT were calibrated. The accuracy of positioning data provided by VRS to the P3-AT was investigated under both static and dynamic conditions at 25 cm to 20 m distances of movement. We saw a standard deviation in the static test of less than 0.03 m, and the root mean square (RMS) to be very close to the specified distance of movement. The results show that VRS can provide the P3-AT with accurate positioning data regardless of pavement types and VRS systems. This study also demonstrated the use of P3-AT in positioning distresses on the pavement, the P3-AT's autonomous monitoring, and its ability to plot slabs on a rigid pavement.

This paper presents an experimental study on the development of dynamic modulus and resilient modulus test of lime-fly ash aggregate mixture (LAA). Mixture was designed and unconfined uniaxial compression tests were conducted at different curing ages. Mixtures curing for 180 days were selected to do dynamic test and resilient test. Test results indicated that LAA dynamic modulus was quite different from resilient modulus, having different stress dependent behavior and being more than 10 times higher than resilient modulus. LAA dynamic modulus had stress and loading velocity dependence, decreasing with the increase of stress and increasing with the increase of loading frequencies and LAA resilient modulus had obviously stress dependence, increasing with the increase of confining stress and deviator stress.

This study aims to introduce alternative design procedures for a flexible pavement base course by utilizing ultimate strength criteria with the sophisticated laboratory results of base course materials. Based on the design protocol, only the design criteria of the horizontal tension and the vertical compression occur at the bottom of the asphalt layer and at the top of the subgrade, respectively are employed. The real behavior of a base course under traffic loads has been rarely accounted into the pavement design protocol. Nowadays, traffic is growing in terms of magnitude and frequency far beyond the past causing premature deterioration in base course layers leading to major damage in pavements. The study presents theoretically a more suitable approach of stress and strain distributions in a flexible pavement using the finite element method. The effects of uniform design pressure and material attributes generated when a vehicle travels, namely the stress and strain contributions between tires and pavement layers, were investigated. Moreover, new design criteria for an unbound granular layer were defined as the ultimate strength design and the bearing capacity factor resulting from the application of the shallow foundation bearing capacity concept within the California Bearing Ratio (CBR) results.

Utilization of crushed recycled concrete aggregate (RCA) in highway projects has become increasingly common due to many advantages both environmentally and economically. To understand its behavior more, a series of repeated load triaxial tests were conducted to assess the permanent deformation (PD) characteristics of RCA, a basaltic virgin aggregate (VA), and a blend of the two when used as an unbound layer in pavements. Tests were performed on samples at their optimum water contents and maximum dry densities. Factors influencing the PD of these materials are discussed. This study examines the applicability of several PD models on these materials. A model that that is simple, that incorporates the variation of PD with stress level and number of load cycles, that contains statistically significant parameters, and yet that fits the data well is identified. This model can be used by engineers to design roads using recycled materials more expediently, thereby aiding the profession's progress towards greener highways.

Mixture formulation and in-situ quality control of the stabilized soils often represent difficult and challenging tasks. The present paper addresses the possibility of using a variant to a recently developed non-destructive technique for continuous monitoring of stiffness of hardening materials as a supporting means to the above-mentioned tasks. The material to be tested is placed inside a polycarbonate mold placed in simply supported conditions. The technique is based on the continuous monitoring of the first resonant frequency of this composite beam, which evolves as a consequence of the hardening of the material, and can be correlated with its E-modulus. The usefulness and potential of this experimental methodology for mixture formulation and quality control of stabilized soils is shown through a series of tests conducted on laboratory since the instant of mixing until 7 days. The conducted tests include complementary methodologies of characterization such as E-modulus measured on specimens with strain instrumentation, as well as monitoring with recourse to bender-extender elements.

The concept of applying Decorative Concrete Overlays (DCO) in infrastructure is an innovative solution that supports the widespread implementation of green engineering through Context Sensitive Solutions (CSS). The purpose of this research was to determine the limits of durability on decorative concrete overlay in terms of bond strength. Although DCO has been used extensively in horizontal applications such as sidewalks and driveways, the parameters of feasibility and durability must be tested for its use on vertical infrastructure surfaces (bridge piers, traffic barriers, noise walls, etc.). This study looks at initial evaluation of these parameters by conducting laboratory testing to measure flexural fatigue and adhesion strength of DCO on two sets of specimens varying in age; 28 days old vs. 125 days old. The flexural fatigue results proved that the bond between concrete and DCO was very effective. Even though the concrete finally failed under the increasing load, the DCO product remained completely bonded as evidenced by the cracked chips of specimen surface. The adhesion strength of the DCO bond to beam specimens varied and results indicated that this difference in strength is due to the thickness of the DCO coating rather than the age of the concrete.

This study investigates de-bonding of asphalt concrete (AC) layers in flexible pavements and determines how de-bonding affects the performance of these pavements using mechanistic models. At present, all flexible pavement design methods assume that there is complete bonding between all AC layers. In complete bonding conditions, the strain at the base of the asphalt layer are transferred to the asphalt layer below, and the displacement at these locations is equal. These assumptions are made to facilitate the modeling of AC pavements. However, in reality, these assumptions are not completely satisfied. Materials in each layer are not identical so the response to traffic loading is different. Using complete bonding conditions in flexible pavement design thus reduces design reliability due to increasing traffic volumes, traffic speed, and tire pressure. Current mechanistic-empirical analysis shows that 90% of the pavements presented in this study fail by top-down cracking if de-bonding occurs between the AC layers. Bottom-up cracking and AC rutting also increase significantly in de-bonded environments. This study recommends the development of a model that accounts for partial bonding/de-bonding in flexible pavement design.

This paper describes a new Finite Element Modeling Laboratory (FEMLAB) model that can be used to predict pavement strength development and consequently the pavement joint-sawing and opening times. The strength prediction was based on the temperature history of the concrete pavement, which was determined by the rate of heat generation and the heat exchange between the pavement and the environment. Pavement joint-sawing and opening times were defined as the times when concrete strength reached 4.3 and 24.1 MPa, respectively. Using this model, the effects of weather conditions, fly ash and slag replacement, concrete placement time and temperature, and pavement thickness on concrete strength, joint-sawing time, and pavement opening time were evaluated. Results showed that weather conditions and the use of fly ash and slag had a significant impact on strength development, joint-sawing time, and pavement opening time.

Longitudinal joint separations are often observed in concrete pavements. An innovative repair procedure was developed in this study for slot stitching in faulted or separated longitudinal joints. It involves with three stages: (1) low pressure grout to restore support under slabs that exhibited signs of pumping and faulting (2) the slot stitching method of retrofitting tie bars, to restore lateral restraint and load transfer across longitudinal joints, and (3) latex modified concrete overlay to restore proper elevation to slabs that had faulted. This paper discusses the results and lesson learned from the first implementation project on US Highway 75 near Sherman, Texas.

With an ultraviolet radiation aging simulation system, designed by Ye Fen (2005), this chapter proceeded with the short-term aging on rubber asphalt indoor in the conditions of different aging time and temperatures. Laboratory tests on penetration, softening point, ductility of 5 °C, viscosity, elastic recovery were implemented to qualitatively analyze the relation between macro-indicators and micro ones. It was aimed to screen rational indexes to characterize the aging degree of rubber asphalt. The test results took softening point as a parameter and viscosity as a reference one during the kinetic equation's deducing. Furthermore, this experimental study introduced the concepts of asphalt aging degree and anti-aging factor, and established evaluation system of rubber asphalt anti-aging.

Water absorption is a significant specification for aggregates which is used in highways. The performance of aggregates changes after absorbing water, then it effects in highways layers such as base, subase, capping. This is why these materials must comply requirements of codes and standards. With regard to the increasing trend of application of recycled aggregates in highways layers, this issue needs more investigation. This research is only a part of our large research programme on three different purposed mixes of unbound subbase mixture below: (1) 100% Recycled Concrete Aggregate (RCA); (2) 100% Lime stone (NA); (3) 50% Recycled Concrete Aggregate (RCA) + 50% Reclaimed Asphalt Pavement (RAP); Water absorption for each mix has been performed in different size fraction with pyknometer and wire basket methods. The relationship between density, grading and water absorption and its comparison for mixes would be indicating the changes in behavior of aggregates and future performance of layers. As further information this research is being performed at Kingston University and some complementary parts to compare are doing in Tehran Municipality.

This paper carried out a research on variable paramenters of GTM tests of different asphalt mixture. A correlative analysis was made between those parameters and laboratory results of the corresponding triaxail repeated load creep tests. The paper concludes that Parameter K1 of compaction curve which is obtained from GTM test (K1 here refers to the average slope of compaction curve from the start of compaction to 97% density) can show high temperature stability performance of asphalt mixture better as Parameter K1 has a good correlative relationship with creep stiffness modulus of triaxial repeated load creep test, and the linear correlation coefficient is above 0.90. Thus, it can be adopted as a simple and practical method to evaluate high temperature stability performance of asphalt mixture.

A summary of stone aggregate classification for pavements in Colombia, is presented. The rocks of Colombia, an Andean country originated in a tectonic convergence zone, are classified into seven families of similar behavior; five include sedimentary rocks (limestones, cretaceous and tertiary sandstones, chert and muddy rocks), the last two ones not very used in pavements in another countries, especially the muddy rocks, due to its limited resistance and scarce durability in the case of clayey and micaceous rocks. Classification criteria and its distribution in the Colombian national territory are introduced in this paper.

This paper review the properties and applications of high performance concrete (HPC). HPC is usually designed based on the requirements for specific applications and environments, which decides the constitute materials and mixture proportions for the HPC to be produced. The strength of concrete is probably the most important overall measure of quality, but other properties such as shrinkage, creep, permeability, frost resistance and durability may also be critical. HPC has been used for all kinds of transportation infrastructures in the world.

The potential leachability of five asphalt binders was studied in the present study. The deionized water was the leaching agent and the content of chemical oxygen demand (COD) in the leachates was used to evaluate the leachability of asphalt binders. It was found that some components could leach from asphalt into water, and the COD in leachates increased with the leaching time. Four influence factors, including temperature, time, NaCl content, as well as pH value, were investigated to obtain the optimal conditions via orthogonal experimental design and single factor test, under which the COD of leachates reached maximum value. GC/MS analysis of the leachates showed that the oxygen compounds were the dominant part and hydrocarbon followed.

This study presents a kind of new model correlates air and pavement temperatures in bituminous pavement. Based on abundant measured temperature data in Henan Province, China, distribution laws in asphalt conctete pavement temperature is studied detailed and the dependency between air and pavement temperature is discussed by the method of regression analysis. Considering the impact on asphalt concrete pavement temperature caused by rising and falling of air temperature in different time periods, the relationships between pavement temperature and air temperature in different air changing periods are studied respectively. Finally, the prediction models of asphalt pavement temperature based on various air temperatures time periods are established. Comparisons between measured and predicted asphalt pavement temperatures indicate that these models are equipped with comprehensive applicability and excellent accuracy.