Material Design, Construction, Maintenance, and Testing of Pavements: Selected Papers from the 2009 GeoHunan International Conference

This paper documents the first warm mix asphalt field trial placed by the Texas Department of Transportation in 2006 using the emulsion based technology (Evotherm) developed by MeadWestvaco. The production, laydown, and compaction characteristics of warm mix were compared with a conventional hot mix asphalt control using a standard mixture design. Field-mixed, lab compacted samples were evaluated for production density, moisture susceptibility and cracking resistance. Field cores were obtained after one month and one year of service and evaluated using Hamburg Wheel-Tracking Tests and the TTI Overlay test. Cores were also evaluated using X-Ray computed tomography to determine the distribution of air voids versus depth in the compacted sample. Field performance of the warm mix is comparable to the hot mix control section after two years of service.

This paper describes the application of adaptive neuro-fuzzy inference system (ANFIS) methodology for the backcalculation of airport flexible pavement layer moduli. The proposed ANFIS-based backcalculation approach employs a hybrid learning procedure to construct a non-linear input-output mapping based on qualitative aspects of human knowledge and pavement engineering experience incorporated in the form of fuzzy if-then rules as well as synthetically generated Finite Element (FE) based pavement modeling solutions in the form of input-output data pairs. The developed neuro-fuzzy backcalculation methodology was evaluated using hypothetical data as well as extensive non-destructive field deflection data acquired from a state-of-the-art full-scale airport pavement test facility. It was shown that the ANFIS based backcalculation approach inherits the fundamental capability of a fuzzy model to especially deal with nonrandom uncertainties, vagueness, and imprecision associated with non-linear inverse analysis of transient pavement surface deflection measurements.

Within the context of the long-term pavement performance (LTPP) program, the purpose of the specific pavement studies-5 (SPS-5) experiment is to analyze the rehabilitation of asphalt concrete (AC) pavements. Most of the existing literature related to SPS-5 experiments addresses the effects of overlay thickness, overlay mix type, and pre-overlay preparation on the performance of AC pavements. A complete evaluation of the eight test sections (i.e., eight rehabilitation strategies) at one SPS-5 site is lacking in existing reports. In this study, grey relational analysis (GRA) was employed successfully to conduct studies on four SPS-5 sites in California, Colorado, New Jersey, and Texas, which are located in four climate regions. The long-term data of International Roughness Index (IRI), rutting, and three distresses (including longitudinal cracks, alligator cracks, and transverse cracks) were used to determine the effectiveness of eight rehabilitation strategies. The resulting ranking in effectiveness of rehabilitation strategies used in this study aligns well with the existing literature. With GRA the effectiveness of rehabilitation strategies can be quantified while depending less on engineering judgment. Evaluations based on the GRA provide a viable alternative for engineers when determining the best rehabilitation strategies for comprehensive LTPP or other studies.

This paper presents the findings from a study in which a common type of Loaded Wheel Tester (LWT), the Asphalt Pavement Analyzer (APA), was used to evaluate the rutting characteristics of HMA mixtures at the Oval Test Track at the National Center for Asphalt Technology (NCAT). Mixtures from twenty six test sections were tested by APA. The specimens used for APA tests included the laboratory compacted cylindrical samples through the Superpave Gyratory Compactor (SGC) at four and seven percent air voids. The results from this study indicated that APA rutting at 500 cycles correlated strongly to the final APA rut depth at 8000 cycles. Regression analyses revealed that the APA rutting for SGC-compacted specimens at seven percent air voids correlated reasonably well (R² = 0.64) to the field measured rut depths; whereas the APA results from lab-compacted specimens at four percent air voids had a weak correlation (R² = 0.20) to the field rutting measurement. Based on the results from this study, it was suggested that for QC/QA purpose, the number of cycles in APA rutting test might be significantly reduced from the current 8000 cycles. Specimens at seven percent air voids were recommended for rutting evaluation.

The Rolling Dynamic Deflectometer (RDD) is a state-of-the-art device that has been used in project-level pavement studies to measure continuous deflection profiles along both highway and airport pavements. Because the RDD deflection measurements are made using contact rolling sensors, the physical and rolling-noise characteristics of the sensors limit the maximum RDD testing speed. In this paper, a two-part study is presented to improve the RDD testing speed and characterization of rolling noise. The first part involves development of second-generation rolling sensors. Field trials using the second-generation rolling sensors on a flexible pavement show significant improvements in testing speed and rolling-noise minimization. The second part involves improving the understanding of the noise that is simultaneously collected with the input RDD signal. This noise is referred to as rolling noise. This effort was achieved by analyzing RDD data collected from numerous project-level studies that involved different deflection levels, pavement surface roughnesses, and testing speeds. These data allowed development of a generalized rolling-noise envelope.

Long tunnel asphalt pavement construction, particularly due to the lack of ventilation, still handicaps the construction process in China and even in the world. Based on the actual Emulsion Warm Mix Asphalt (EWMA) long tunnel pavement project, EWMA's characteristics have been studied compared with conventional Hot Mix Asphalt (HMA). Further more, EWMA compactibility performance at various compaction temperatures has been evaluated by SGC test. The field pavement performance has been evaluated according to related specifications. The reductions in fuel consumption and gas emission of EWMA have been quantified in contrast to conventional HMA. The study shows that EWMA can reduce 30°C~40°C compaction temperature and have significant lower energy consumption and emission in tunnel construction, and increase about 10 percent rutting resistance compared with conventional HMA. Therefore, EWMA is remarkable material for long tunnel asphalt pavement construction.

Construction rubbish including waste bricks and concrete blocks, can be recycled into brick-stone aggregate through pre-screening, crushing, screening and blending. Using proper mix proportions of lime-fly ash, cement, or cement-fly ash stabilizes the material which can then be used as pavement base material. The unconfined compressive strength, modulus, frost resistance and anti-brushing performance of this recycled material can meet the required specifications. Through three experimental sections, the conclusion above is validated.

As of 2001, the Texas Department of Transportation (TxDOT) has been using a 25 mm nominal maximum aggregate size (NMAS) Stone Fill HMA (SFHMA) mix as the main structural rut-resistant layer in perpetual pavement structures. The SFHMA mix-design basically consists of moderately low asphalt-binder content with a relatively stiff performance-graded (PG) asphalt-binder on the order of about 4.2% content and a 25 mm NMAS coarse aggregate gradation. To date, over eight different SFHMA mix-designs have been utilized on different in-service perpetual pavement projects in Texas. The objective of the work presented in this paper was to review and document the workability characteristics of these coarse SFHMA mixes as observed both in the laboratory (during mix-design and material property characterization) and in the field (during construction). In general, these SFHMA mixes were found to have poor workability characteristics. Remedial measures as employed both in the lab and field to improve the SFHMA mix workability and other material property characteristics are also presented in the paper.

The Ministry of Transport (MOT) in Saudi Arabia uses Pavement Condition Rating (PCR) to report pavement condition. The PCR was developed by the World Bank in 1986. PCR is based on International Roughness Index (IRI), Rutting (RUT), Cracking (CRA), and Raveling (RAV). The MOT collects pavement condition data using a digital inspection vehicle (DIV). On some expressways, the MOT measures the Skid Number (SN) using a Skid Test Unit as complimentary measurement for safety issues. The objective of this paper is to develop a general prediction model for The Saudi Arabia Inter-Urban road network. Two models have been developed for the Inter-Urban road network using 10 years survey data for overlaid sections on some expressways in the network. One model is for PCR and the other one is for IRI. The PCR model is a function of pavement age (T), Traffic Volume (TV), and IRI. The IRI model is a function of RUT, RAV, and CRA. Overlaid sections across the entire network have been selected to study the mechanisms of pavement deterioration, to develop the model and to draw conclusions.

The DCP (Dynamic Cone Penetrometer) and LWD (Light Weight Deflectometer) are becoming ever more popular as mechanistic-empirical pavement design/construct procedures evolve. These instruments provide the ability to quickly, accurately, and economically measure shear strength and stiffness of in-place base course and subgrade material, thus obviating the need for density testing. These instruments are rugged, portable, easy to operate and do not have the regulatory disadvantages of a Nuclear Density Gauge. This paper outlines the genesis of the DCP for soil testing and the respective applications for various DCP configurations. The various types of LWDs and the results they produce are described. Finally, on going efforts in the use of these instruments as well as standards for QC/QA (Quality Control /Quality Assurance) for subgrade and aggregate base for roads are discussed.

The influence of bonding condition between surface course and uncracked base course on pavement structure mechanical response has been studied for many years. All research indicate that the bonding condition should be firm as far as possible to decrease the flexural stress at bottom of layers. It is inevitable for semi-rigid base course to crack due to temperature shrinkage and moisture shrinkage. Shear stress at crack tip due to offset load applying on one side of crack was calculated at different friction coefficient between surface course and cracked base course. Flexural stress at crack tip due to temperature dropping was also calculated at different friction coefficient between surface course and cracked base course. The calculated data show that shear stress and flexural stress at crack tip both increase when the friction coefficient increases, which indicates that the bonding condition should be as smooth as possible for cracked pavement structure. For actual pavement structure, there exists uncracked section between two adjacent cracks. It is discussed based on stress data to estimate which section cracks firstly. The results indicate that there exists the optimum bonding condition between surface course and base course.

The present study is a part of a large project on the valorisation of concrete demolition aggregates in order to contribute to their re-use in the field of the civil — engineering, particularly in roads. After the recycled aggregates are sorted and selected, their characterization is based on the comparison of their physical and mechanical behaviors with the natural aggregates (sand and gravel). Then their responses under the Proctor and the CBR tests are studied before and after treatment with sand, cement and clay additions. However, the results obtained showed that the characteristics of the recycled aggregates are lower than those of the natural aggregates. We thought then to improve them by the additions quoted herebefore. The addition of these materials, allowed to appreciably ameliorate some of their physical and mechanical characteristics approaching those obtained for the natural aggregates.

Shrinkage cracks are easy to occur in cement-treated macadam base when temperature and humidity change. In order to study the drying shrinkage and cracking performance of different cement-stabilized macadam base materials, dry-shrinkage performance tests were carried out by mixing the cement-stabilized macadam mixture with different gradations and cement dosages, ranging from 2% to 5%. Hence, a model for evaluating the dry-shrinkage performance of cement-stabilized macadam mixture was made on the basis of the mixture's dry-shrinkage performance's relationship with water loss rate, exposure time, cement dosage, gradation and other elements. The experiment shows that the mixture's dry-shrinkage performance is the best when mixed with fine gradations and the cement is added by 3% to 4%.

This study aims to address the development of performance based payment adjustment methods. First, this study describes the cases in which the pay adjustment has been applied and influential factors used in forty states of U.S. Based on those preliminary studies, it has been determined that the applicable factors that can be used for the pay adjustment of asphalt pavements in Korea. This study develops a more systematic and reliable algorithm that can be trusted by both builder and vendee. The percent within limit (PWL) has been analyzed as a rational estimation and measurement tool for asphalt pavements. The correlation between fatigue cracking and pay adjustment factors has also been investigated in this study. The fatigue life was increased or decreased due to changing asphalt content, density and gradation.

The Enhanced Integrated Climate Model (EICM) is a program that integrates most of the climate conditions to simulate climate effects on pavements. It was originally designed for all regions in the United States. However, it was proposed on the basis of the nation wide average climate data and not accurate for regional conditions. Therefore, it is necessary to calibrate the EICM using local climate data before its application by state DOTs and other agencies. In the State of New Mexico, because of its special climate condition, the calibration of EICM is very important. In this paper, the EICM was used to predict pavement temperature profile with the input data obtained from the LTPP Datapave. Then the EICM-predicted temperatures were compared with the measured temperatures to validate the feasibility of the current EICM in New Mexico. Finally, the correlation between the EICM-predicted and measured temperatures is provided.

The subsurface formation at sites along the western Red Sea coast of Saudi Arabia often have loose to medium dense silty sand at several parts. This type of material was encountered at levels immediately below the foundation depth commonly used in practice. These soils undergo excessive settlement when supporting concrete structures, slab on grade systems and pavement structures. This work was aimed at studying the improvement provided by preloading technique to these coastal deposits. Technical College Building Complex site located at Al Qunfoda was selected for this study. The site was preloaded using 4.5 to 6m height of sand over six month period. The settlement was monitored every week throughout the period of preloading. The density and compressibility of the formation was noted to improve in different stages; an initial fast stage occurring within the first four weeks, intermediate stage which continued for 12 weeks and a slow stage which is noted to continue for more than 26 weeks. A final stable stage is considered when no variation in settlement can be reported over a satisfactory period. The process improved the site and established a close to uniform density across the area studied. Plate load tests carried out on improved areas confirmed that the settlement after preloading was reduced to tolerable limits for a particular foundation stress range. This paper provides a guide for monitoring, verification and decision making tool for practicing geotechnical engineers.

Three types of aggregate gradation with different nominal maximum size were designed by Bailey method for large stone asphalt mixes (LSAM). The optimum asphalt content was then determined by Gyratory Testing Machine (GTM) method and Marshall method, respectively. A series of tests were carried out to investigate the performance of the obtained LSAM. The optimum asphalt content(OAC), volume of voids(VV), voids in mineral aggregate(VMA) and voids filled with asphalt(VFA) of specimens prepared by GTM method showed smaller values whereas bulk density is larger. Furthermore, higher temperature stability and poorer crack resistance at low temperature of the former can also be observed.

The problems associated with the environmentally safe and efficient disposal of waste continue to grow. In many areas, existing landfills are beginning to fill up, and a "not-in-my-backyard" philosophy has made the establishment of new landfills very difficult. The cost of disposal continues to increase while the types of wastes accepted at municipal solid waste landfills are becoming more and more restricted. One answer to all of these problems lies in the ability of society to develop beneficial uses for these waste products. Pakistan is a developing country and in order to open new avenues of prosperity there is a need to develop roads network throughout the country. The use of waste byproducts would also relieve some of the burden on the natural resources / virgin materials. A research was undertaken to study the use of fly ash and granulated blast furnace slag as road construction materials and to see how these can improve the properties of asphalt mix design at high temperatures.

In the past decade, numerous industrial and public initiatives have been launched in order to make knowledge, practices, and mentalities evolve in relation to the acceptability of using waste instead of raw materials as construction materials (Ahmed, 1993). The objectives of the initiatives have been to evaluate current practices and to make new solutions and channels for beneficial use emerge. At the same time, the scientific and standardization communities have developed methodologies and tools to fit the assessment needs (Sherwood, 2001). This part of the research presents the results of research involving metal slag as the base material for road constructions in Istanbul, Turkey. The design parameters for the roads constructed using the discarded metal slag were presented based on laboratory model studies. Numerical analysis and field performances were also conducted for the metal slag. Groundwater and surface water analyses conducted before and after the construction were taken into consideration. The metal slag contains some compounds that have pollution potential. Although the leachability of most compounds is low (below the maximum limit) for conditions in civil engineering applications, corrosion occurs at the exposed parts of the metal slag in poor drainage conditions. The conclusion of this research supports the view that the selected waste material is an environmentally acceptable base material for use as an alternative soil stabilization method in road construction. Consequently, it is concluded that the usage of metal slag waste material as the base of road construction is possible for every aspect of this research.

In order to resolve the runoff of rainwater resource, to prevent the spoliation of ecology, and to reduce the effect of heat island, the search for a suitable mix design of the pervious concrete for Taiwan is not a trivial issue. The main purpose of this study is to find the suitable pervious concrete mix for pavement engineering. The two experiments included in this study are: (1) test the suitable mix design of pervious concrete; and (2) test certification in the field construction of pervious concrete on parking lot. Pervious pavement composed of 8-in surface layer (pervious concrete) and a 4-in base layer (gravel) were made. The results showed that the compression strength of the two pervious concrete core specimens from test certification in the field construction (parking lot) exceeds the ordinary concrete structure specification (175 kg/cm²). The field permeability test for the parking lot is about 1000 ml/15sec. The water penetration of the above pervious concrete is very good and no cracks were present on surface. Therefore, it is an environment-friendly material for pavement.

It is well known that the quality of cement concrete highway surface has significant influence on the vehicle running speed. This paper discusses the performance of cement concrete mixed with pulverized coal ash based on the experimental study. Results show that when adding with pulverized coal ash, the anti-booklet intensity will be enhanced, the abrasion resistance can be improved and water gain rates and the cement hydration speed can be cut down effectively. It should be noted that the pulverized coal ash cement concrete must consume massive pulverized fuel ash which will occupy land area and pollute the environment.

Fibers are extensively used in civil engineering applications for many years. The fibers provide three-dimensional reinforcement of the mixture. The main objective of paper is to evaluate effect of fibers on performances of asphalt mixture at high temperature. Three different fibers were used as modifiers: polypropylene fiber, polyester fiber and cellulose fibers. An SHRP's Dynamic-Shear-Rheometer (DSR) was employed to investigate the rheology property of asphalt-fiber mortar. The wheel tracking device was employed to evaluate rutting resistance of asphalt mixture. The strengthening mechanism in fiber-reinforced asphalt mixture was studied. DSR test results demonstrated that fiber asphalt mortar showed remarkable improvement of properties in comparison with the control asphalt mortar. The wheel tracking test results showed that fiber performed different performance level but showed more resistance to permanent deformation according to the fiber type and fiber contents.

The existing studies on distresses in deck pavement indicate further research into the structural behaviours of orthotropic steel bridge decks is necessary to better understand this important issue. In this regard, this paper first presented a brief review of principles for the design of pavement on orthotropic steel plate decks. Second, critical issues including local displacement and negative bending behaviour under truck loading, main distresses in asphalt deck surfacing and their mechanism, and basic requirements for the asphalt surfacing were discussed in detail. Finally, a fatigue based mechanical-experimental design procedure was proposed for the designing of deck pavement. In addition, it is recommended that based on this study, a new theory to accurately describe the composite interaction between asphalt layer and steel deck plates, interaction between asphalt layer's fatigue and bonding membrane damage and their influences, and a more precise performance based design method can be established.

Reflective cracking is one of main distresses for cement/lime/flyash stabilized base in China. Although flexible base can be and has been utilized as sandwich layer to reduce reflecting cracks from stabilized base, the repetitive truck traffic load may cause higher tensile stress at the bottom of asphalt surface course because of large deformation from flexible base. The high tensile stress may lead to fatigue cracking. To minimize the tensile stress at the bottom of the asphalt layer and to establish optimum structures to reduce reflective cracking, nonlinear finite element technique was utilized to support three experimental pavements in Tonghua Highway in Jilin province. Base on the analyses, pavement structures 1 and 2 are recommended. In addition, for pavement structure 1, the optimal design is to include 7–12cm of AM-30, 10–15cm of flexible base, and 30–45cm of semi-rigid subbase (lime-flyash stabilized soil or cement treated base). Furthermore, for pavement structure 2, the optimal design is to include 15–20cm of flexible base, and 25–40cm of semi-rigid subbase (lime-flyash stabilized base or cement treated base).

Stress due to the temperature and moisture gradients in concrete slab often causes pavement curling and warping that may further cause concrete crack if the slab is under restraint conditions. The adding of supplementary cementitious materials (SCMs) can reduce the risk of cracking by reducing the temperature stress. However, under cold weather condition, the slower strength development due to SCMs could increase the risk. This paper reported a study result of using blended cement to reduce such as risk. In this study, the properties of ternary cement concrete, such as setting time, heat of hydration, and datum temperature, were investigated. The risk of early-age cracking for different concrete mixes under different weather conditions was evaluated by the HIPERPAV. The test results indicated that fly ash replacement generally increase the setting time; while the slag replacement reduced the setting time. Both fly ash and slag replacement reduced the generated heat. When the amount of slag increased, the datum temperature and activation energy increased. HIPERPAV analysis indicated that there was little risk of early-age cracking for binary or ternary cement concrete under average summer weather conditions due to proper strength development of the concrete. However, the risk of early-age cracking for the concrete pavement increased under spring or fall weather conditions.

With the characteristics of Evotherm warm mix asphalt technology introduced, the existing problem about hot mix asphalt technology applied on ultra-thin pavement was put forward. The research on the workability of Evotherm warm asphalt mixture was conducted by measuring the Brookfield dynamic viscosity of Evotherm warm mix asphalt and hot mix asphalt (HMA) at different temperatures, which can guide the mixing and compaction temperature range. Based on test results of laboratory performance, the warm mix asphalt ultra-thin pavement was paved in China at low air temperature. The temperature vs. time curve of Evotherm warm asphalt mixture was derived theoretically by Pavecool® software in advance. The field temperature vs. time curve was also obtained by field test result of Evotherm trial road, which can guide the compaction occasion of the Evotherm warm mixture. The pavement performance of trial road was positive, which demonstrated that the application of Evotherm warm mix asphalt on ultra-thin pavement was successful at low air temperature in China.

Perpetual pavements are considered by many pavement experts to be the long-term solution to increasing traffic volumes and related pavement rehabilitation costs and user delay costs. The paper reviews the problems that perpetual pavements are experiencing, such as moisture infiltration/damage, and layer debonding. There is no indication that the pavement design methods presented in this paper account for moisture infiltration/damage or debonding in their designs. This is primarily due to the lack of an appropriate design method, which can include infiltration/damage and debonding it its design. Analysis of current field performances of selected perpetual pavements and mechanistic-empirical predicted performances is also shown. From this analysis, three out of six perpetual pavements are performing better than expected; two pavement sections are performing as predicted, and one pavement section performing worse than expected.

The number of superheavy load permits in the last five years has increased by a factor of 13.3. With continued economic development in Texas, superheavy load permits are expected to continue to increase. Significant efforts have been made to monitor, evaluate, and analyze pavement damage caused by the superheavy load moves. This paper documented six cases of pavement surface damage as the result of superheavy load moves. It was found that superheavy loads can cause serious damages to fresh seal coats if not properly routed. Based on these six case histories, it was concluded that seal coats are most vulnerable to damage under one or more of the following factors: (1) time after placement (the first 5 weeks are critical), (2) high temperatures, and (3) steep grades in combination with too few drive axles. The results indicate that even after repairs, the pavement condition is not as good as the original undamaged condition, as the damages are still visible approximately six years after repairs. The findings and lessons learned from these six cases can be used by other transportation authorities to improve their regulations and permitting procedures so that damage caused by superheavy load moves is minimized.