bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Elastic and Plastic Subgrade Soil Parameters for Asphalt Cracking and Rutting Prediction
Authors: Behzadi G. , Yandell W. O.
Published: August 2018

A preliminary step in the prediction of rutting and cracking in a number of accelerated loading facility trials in Australia is presented. The results of laboratory repeated load triaxial tests were used to characterize the residual and resilient deformation of a silty clay subgrade material. The analysis of permanent deformation indicated that the well-known model ∈p = INS can be used to estimate the accumulated strain at any number of loading cycles. The parameter S (the slope of the line in a plot of log ∈p –log N) was found to be independent of stress and density, but very small increases were observed as moisture content increased. The parameter I (the intercept in a plot of log ∈p –log N) was found to be most sensitive to deviator stress. The test results also indicated that I increased with increasing moisture content and decreased as dry density increased. The analysis revealed that an exponential relationship existed between I and deviator stress. This relationship was used to develop a constitutive model for silty clay based on the previously mentioned well-known model. The constitutive model obtained would be able to predict the plastic strain under any number of loads at any specified stress level. Resilient deformation analysis has shown that resilient modulus initially decreased rapidly with increasing deviator stress and then increased slightly or was nearly constant. The elastic and plastic parameters will be used as input for performance predictors such as VESYS and Mechano-Lattice.
Experiments with Cold Mixes on Laboratoire Central des Ponts et Chaussées Fatigue Test Track: Behavior under Traffic Loads, Mechanical Characteristics, and Modeling
Authors: Corte Jean-Francois , Serfass Jean-Pierre , Brosseaud Yves , Joly André
Published: August 2018

A joint experiment has been set up by Laboratoire Central des Ponts et Chaussées and SCREG using the Nantes circular test track. Four pavement structures have been constructed, each consisting of a layer of graded crushed aggregate and 10 cm of bituminous material. The bituminous mixes are made up of a reference base hot mix, a reference conventional emulsion-bound granular material, a double-coated cold mix, and an experimental special emulsion-bound granular material. Sub-grade low bearing capacity and limited pavement thicknesses resulted in high deflections. The structures were submitted to 1,900,000 loadings of 6.5 t dual wheels. Loading was carried out in two phases: consolidation, then fatigue. Monitoring of the structures' behavior showed that deflections remained high and rutting occurred in subjacent untreated materials, but not in the bituminous mixes. High strains were recorded in the cold mixes. Cracks became visible fairly early in the four structures. They nevertheless withstood the loadings without requiring any maintenance. Besides, numerous laboratory tests were carried out on laboratory mixes and samples taken from in situ layers: compressive strength, resistance to water, compactability with gyratory shear compactor, and static and dynamic moduli. The results enabled a more complete characterization of cold mixes. They also validated the concept of the innovative cold mixes tested. Finally, theoretical analysis was conducted, resulting in a fairly satisfactory structure modeling, using materials nonlinearity.
Field Verification of Moving Load Model for Pavement Response
Authors: Siddharthan Raj , Yao Jian , Sebaaly Peter E.
Published: August 2018

A validation study undertaken to verify the predictive capability of a recently developed moving load model to predict pavement response is described. The full-scale field-measured responses of longitudinal strain at the bottom of the asphalt concrete (AC) layer were used in the verification. The field testing program, in which the strain responses induced by a semitrailer truck were measured as a function of vehicle speed, was carried out at the Pennsylvania State University test track. The material behavior of the AC layer, which was assumed to be viscoelastic, was deduced from the laboratory behavior of the AC and from the backcalculated AC modulus from falling-weight deflectometer data. The unbound material layer properties were assumed to be elastic. The moving load model reproduced many important general observations made from the field tests, such as the existence of a complex interaction in the case of a tandem axle configuration and the strong influence of vehicle speed on the strain response. Good agreement exists between the predictions made by the model for the strain response for single and tandem axle configurations under different loading and vehicle speeds and those measured in the field. The difference is less than 14 percent, thus verifying the applicability of the moving load model to predict pavement response.
Impact of High-Pressure Tires and Single-Tired Axles in Oregon
Authors: Bell C. A. , Randhawa S. U. , Xu Z. K.
Published: August 2018

The growing concern in Oregon in the early 1990s that the use of single tires on the nonsteering axles of trucks may be growing and leading to increased damage to pavements is addressed. An associated concern was that tire pressures may be increasing and contributing to increased damage. Single tires are used in two ways on nonsteering axles. Wider-than-normal tires (wide-base) may be used instead of traditional dual tire assemblies, or singling out of dual tires may be done, where the inside tire of the duals is removed. An extensive survey of trucks was conducted at Oregon's five ports of entry in 1992 to establish the pattern of use of single tire and tire pressures. The data were compared with those available from studies conducted in Oregon in 1986 and 1989. There did not appear to be a growth in use of single tires or a trend of increasing tire pressures. However, the data collected previously for single tire use was limited. The surveys conducted in 1992 showed that single tire use varies throughout the state, depending on the commodities hauled in an area. Singling out tends to be used where relatively light articles are being hauled, whereas wide-base tires appeared to be concentrated with trucks hauling forest products. The surveys indicated that less than 10 percent of trucks used single tires on nonsteering axles. The use of single tires on nonsteering axles does not appear to be a significant problem. However, on the basis of the analysis conducted in this study, some control may be appropriate because such tires could cause more damage than similarly loaded dual tires. Partial singling out of tandem axles has the potential to be particularly damaging. Such axles have six tires instead of the usual eight. However, there are many options for using single tires and some are used with axle configurations that cause less pavement damage than alternatives using dual tires. An example of this would be a tridem axle with single tires versus a tandem axle of the same weight using dual tires. Any control of single tires should not limit their use with less damaging axles.
High-Load Elastomeric Bridge Bearings
Authors: Van Lund John A.
Published: August 2018

The use of elastomeric bearings as high-load bridge bearings for steel and concrete bridges is discussed. The Washington State Department of Transportation's (WSDOT's) experience with high-load multirotational bearings and search for simpler, more durable, and more economical high-load bridge bearings are described. The results of a survey of state departments of transportation indicate that bridge designers have been slow to design elastomeric bearings for the higher stresses permitted by AASHTO Method B. High-load steel-reinforced elastomeric bearings are defined as bearings that are designed for a compressive service stress of 11 MPa (AASHTO Method B maximum) to 15 MPa (German maximum). Design criteria for elastomeric bearings are discussed. A recent WSDOT project is presented. In the case study a four-span continuous curved steel plate bridge is designed for a seismic acceleration coefficient of 0.22 g. At the intermediate piers, high-load steel-reinforced elastomeric bearings are designed for a service load of 339 Mg with a compressive stress of 11 MPa (AASHTO Method B). The seismic forces at the piers are reduced by 50 percent when compared with those with fixed pin or spherical bearings. Constructibility issues, quality control, testing requirements, design loads, and costs are presented. Future research needs are identified. In addition to supporting high loads, elastomeric bearings are durable, simple to install, and maintenance-free and can reduce seismic loads at bridge piers. These bearings are an economical alternative to more expensive disc, pot, and spherical bridge bearings.
Corrosion and Fatigue Resistance Study of Aluminum Bridge Deck
Authors: Thompson Kurt P. , Shives B. Larry , Snodgrass J. S. , Marks C. A. , Hughes R. E.
Published: August 2018

Thousands of bridges on which the U.S. transportation system depends are in need of repair or replacement. Engineers are continually looking for materials that can significantly extend the lives of these structures. The use of lightweight materials such as aluminum could often avoid the cost of the replacement of the sound foundations and steel girders of bridges listed as structurally deficient. However, bridge engineers have not considered aluminum for use as a bridge material because of a lack of information on the in-service performance of existing aluminum bridges and a lack of knowledge about the metal's lower life-cycle costs compared with those of traditional materials. The reconfiguration of the Smithfield Bridge in downtown Pittsburgh from a mass transit–highway bridge to a highway-traffic bridge presented an opportunity for Reynolds Metals Company to analyze the corrosion and fatigue performance of the almost 30-year-old deck and the more than 60-year-old cross members. The results of the study indicate that aluminum is a viable material for bridge decks when it is properly designed into the application.
Proof Load Testing of Highway Bridges
Authors: Saraf Vijay , Sokolik Andrej F. , Nowak Andrzej S.
Published: August 2018

It is estimated that there are more than half a million highway bridges in the United States. Many of these bridges have deteriorated considerably because of age and inadequate maintenance and inspections, whereas the average daily truck traffic and truck loads have increased. Careful evaluation is required to make rational economic and safety decisions concerning the rehabilitation of each bridge. Proof load testing is an efficient tool that can be used to evaluate the performance of existing bridges. The objective of the study was to ensure the safety of two highway bridges located in Michigan by proof load testing. For the first bridge the design details were not available, and the second bridge had heavy corrosion in the lower flanges of its steel girders. Usually, the proof load level is about twice the maximum allowable load. Allowable loads in Michigan are considerably higher than those in other states. Therefore, military tanks on flatbed trailers were used to achieve the high target proof load levels. These tanks were provided by the Michigan National Guard. Load was increased in several steps, and the strains and deflections in the girders were measured. No sign of distress was observed during the tests. The capacity of each bridge was found to be significantly higher than the analytical capacity.
Laboratory Tests of Buried Pipe Installation Procedures
Authors: Zoladz Glen V. , McGrath Timothy J. , Selig Ernest T.
Published: August 2018

Laboratory testing of buried pipe was conducted to evaluate the pipe-soil interactions that take place as pipes are backfilled. The program consisted of 25 tests with metal, plastic, or concrete pipe. In addition to pipe type, test variables included trench conditions, backfill material, compaction method, haunching effort, and bedding condition. The tests were conducted in an indoor test facility designed to allow for the installation of pipe in a realistic manner. Pipe and soil behavior were monitored during installation, and measurements included pipe deflections, pipe strain, pipe-soil interface pressures, soil density, soil strength, and horizontal soil stresses. Backfill was placed to at least 150 mm above the spring line to observe the effects in the important haunch zone. Ten of the tests were continued until the backfill was at least 300 mm over the pipe. The results indicated significant variations in pipe behavior because of installation practices. The wider trench produced greater upward deflections during sidefill compaction. The rammer compactor was the most effective means of achieving high backfill density and stiffness, forcing backfill into the haunch zone, and developing beneficial lateral soil stresses at the sides of the pipe. Installation in trenches with walls of soft materials results in lower lateral pressures and higher invert pressures on the pipe. The coarser-grained backfill material achieved suitable soil unit weight and stiffness with less compactive energy than the finer-grained material. The haunching effort provided improved pipe support in the lower haunch zone.
Design Method for Preventing Longitudinal Uplift of Corrugated Metal Pipe
Authors: Morgan B.C. , Lohnes R. A. , Klaiber F. W. , Kjartanson B. H.
Published: August 2018

Corrugated metal pipe (CMP) culverts in some situations have experienced inlet uplift caused by unbalanced pore pressures. Many state departments of transportation (DOTs) have design guidelines for determining the magnitude of force required to restrain CMP against these uplift forces; however, these specified forces vary considerably. Also, the experimental or analytical bases for many of these specifications are unclear. The wide range of the specified tiedown resistances and the vague rationale for these standards suggest that design criteria based on experiments and analyses are needed. The objective of this paper is to describe a design method, developed from experimental and analytical studies, for determining the force required to restrain a CMP against inlet uplift. The design process presented here provides an easy-to-follow procedure that allows the engineer to make final design considerations based on judgment and experience. The method also indicates that in situations in which the soil or pipe is sufficiently stiff or in which total blockage of the pipe is unlikely, tiedowns may not be required. The design guidelines presented here are compared with the specifications of several state DOTs. This comparison indicates that several of the agencies' requirements are somewhat conservative whereas others may be unsafe, and also suggests that some agencies may be overlooking expanded use of CMP by limiting the maximum diameter of pipe that they allow.
Structural Behavior of Three-Sided Arch Span Bridge
Authors: McGrath Timothy J. , Selig Ernest T. , Beach Timothy J.
Published: August 2018

A study was undertaken to evaluate the methodology used for the structural design of three-sided culverts with arched top slabs. An 11-m span by 3.4-m rise bridge was instrumented and monitored during installation, under an HS-25 + 30 percent live load and at 6-month intervals for 2 years after installation. The bridge consisted of ten 1.6-m-wide precast segments. Three of the interior segments were instrumented with soil stress cells mounted on the legs of the bridge and with anchor pins for use with a tape extensometer to determine change in shape of the bridge. Survey data were taken on the same three segments and the two adjacent segments. Visual observations were also made to monitor cracking. The live load test was conducted with 0.3 m of cover. Final cover was 0.9 m. The bridge showed less movement under the live load than under the 0.9 m of earth load. The 2-year data show that the shape of the bridge and the soil stresses at the sides of the bridge cycle on an annual basis and that the spans have increased 4 to 8 mm over the 2 years since the completion of construction and appear to be still increasing. Overall, the structural performance of the bridge under earth and live loads was excellent. The correlation between the measured behavior and the computer analysis was good except that the actual live load effects were much smaller than assumed for design. The results of the project support the use of finite-element analysis to design such structures.
Buckling Strength of Polymer Liners Used in Sewer Rehabilitation
Authors: Moore Ian D. , Sawy Khaled El
Published: August 2018

Polymer liners are being used with increasing frequency for rehabilitation of damaged pipelines as part of infrastructure renewal in North America and elsewhere. An important consideration for these liners is the buckling resistance to fluid pressures acting on the outside of the liner (between the liner and the original pipe structure). Previous work has used unconservative solutions based on a different thermal buckling phenomenon or fluid buckling solutions for very thin liners. Nonlinear finite-element analysis is used to assess the stability of typical polymer liners fitted within a cracked rigid pipe. Slip and separation at the liner-pipe interface, the external fluid pressures, and the imperfect geometry of the damaged pipe are considered in the study of critical pressures. The liner buckling mechanism is reviewed, with emphasis on the impact of both the hoop and flexural stiffnesses. A parametric study is reported, to demonstrate the influence of thickness-to-radius ratio and imperfection size. Recommendations as to stability enhancement resulting from host pipe support are made. These could be used to design liners after examination of the theoretical results in relation to laboratory and field test data.
Seismic Analysis of Large Buried Culvert Structures
Authors: Byrne Peter M. , Anderson D. L. , Jitno Hendra
Published: August 2018

Field experience indicates that large buried culverts have suffered essentially no damage during past earthquakes when no significant permanent ground movements have occurred. These soil structures, which generally comprise steel or concrete arch members and engineered soil, may have spans of 15 m. Static, pseudodynamic, and dynamic finite-element analyses have been carried out on these structures and indicate that for horizontal seismic loading, the surrounding soil is much stiffer than the arch and results in the seismic load being taken by the soil rather than by the arch. Under vertical seismic loading, the arch is stiffer than the surrounding soil and attracts significant load, which can essentially be accounted for by increasing the unit weight of the soil in proportion to the vertical acceleration. Thrusts and moments in a 10-m concrete arch are examined under combined static and seismic loading (both horizontal and vertical). The results indicate that significant increases in thrust and moment in the arch are predicted for peak ground accelerations in excess of 0.3 g. The good behavior of these structures under such acceleration levels in California, where they are not specifically designed for earthquake forces, indicates that their static design includes sufficient reserve to prevent failure under accelerations of these levels.
Evaluation of Culvert Pipe Made from Waste Truck Tires
Authors: Gattis J. L. , Everett Jess W.
Published: August 2018

Waste truck tires pose special disposal problems. As an alternative to disposal, a private tire recycling company developed a pipe from the tire bead and sidewall. This tire pipe has seen limited use as a roadway drainage culvert. To encourage wider use of this product, an evaluation of its performance was performed. The evaluation consisted of (a) inspections of existing installations, (b) receiving comments from installers and owners, and (c) leakage tests. The field investigations revealed that most tire pipe installations were performing well. An individual tire pipe section was found to be watertight. However, when tested in the open air (not in the ground), the tire pipe joint was found to leak. Development of an improved end connection may improve the utility of the tire pipe.
Fort Point Channel: Concrete Immersed-Tube and Ventilation Building Design
Authors: Valenti Robert , Brudno Alex , Bertoulin Michael , Davis Ian
Published: August 2018

The Central Artery/Third Harbor Tunnel Project in Boston, Massachusetts, is one of the largest highway projects over undertaken in the country. It requires the replacement of the existing elevated artery, I-93, with an underground tunnel extending through downtown Boston and an extension of the Massachusetts Turnpike Authority (MTA) I-90 from its existing termination at the I-93 interchange to Boston's Logan International Airport. The I-90 extension tunnels east under the existing South Station intercity and commuter railroad tracks, under historic Fort Point Channel while crossing above the 1915 twin subway tunnels, and continues through industrial South Boston with ramps surfacing in a new South Boston interchange, the heart of tremendous growth in Boston. From there the tunnel connects to the recently completed Ted Williams Tunnel harbor crossing to East Boston and Logan International Airport. The unique design challenges and solutions relating to the Fort Point Channel crossing, particularly the use of in-the-wet construction with concrete immersed-tube tunnels and the design interface to the ventilation structures, are presented. Structures required for the I-90 extension are concrete immersed tubes and jacked tunnels, as well as more conventional cut-and-cover tunnels, bridges, surface roads, and ancillary buildings. The geometric and physical restraints of the alignment initially required the placement of the ventilation building, which serves the tunnels, on a cut-and-cover tunnel transition section between the jacked tunnels and the concrete immersed tubes. Ultimately, placement of the ventilation building on the immersed tubes created a substantial cost and schedule benefit.
Improved Subway Construction for the 21st Century
Authors: Irshad Mohammad , Dickson John R. V.
Published: August 2018

Despite many innovations and advances in technology, subway construction remains a challenging and taxing proposition, even under the best of circumstances. Given the enormous cost of subway construction and the impact of construction activity on overlying neighborhoods and communities, subway projects can attract adverse publicity and the associated negative public perception of the mass-transit industry. Major cost and schedule overruns are not uncommon. Witness, for example, the bad press that the Los Angeles Metro's subway construction recently attracted in the local and the national press. Against this backdrop, there is a clear need for reviewing the state of the art and for examining the range of options available to owners for minimizing the trials and tribulations of subway construction activity. Drawing upon experience from major subway system construction projects in the United States, particularly the Washington Metropolitan Area Transit Authority (WMATA), and from elsewhere, this study sets out to achieve this objective. Various tunneling methods, including the two-pass, single-pass, the New Austrian Tunneling Method, and the like, are discussed and strong and weak points evaluated. Also discussed are the selection of tunnel boring machines, ground modification techniques, mitigation of environmental impacts, contract format and payment methods, and risk management strategy from the owner's viewpoint. Recommendations are made for developing tactics and strategies to better manage and control the subway construction process. In sum, the paper provides timely information on an important issue typically involving high visibility mega-dollar construction projects.
Reconstruction of Dewey Square Tunnel
Authors: Brenner Brian , Akyali Dincer , Ni Huang , Formosa John
Published: August 2018

The Dewey Square Tunnel in Boston, part of the Central Artery I-93 alignment, is to be upgraded to satisfy current highway standards. The preliminary design includes extensive structural modification. Construction staging plans include a program of inspection and material testing of the existing structure.
Asphalt Concrete Overlay Design Case Studies
Authors: Pierce Linda M. , Mahoney Joe P.
Published: August 2018

During the late 1980s, the Washington State Department of Transportation (WSDOT), the University of Washington, and the Washington State Transportation Center developed a mechanistic-empirical flexible overlay design procedure. Following development, WSDOT implemented this overlay design procedure and has been evaluating flexible overlay projects for approximately the past 8 years. WSDOT rehabilitates about 100 projects each year; approximately 20 to 30 percent of the total projects are designed using the WSDOT overlay design procedure and the AASHTO overlay design procedure (using DARWin). These two procedures are discussed in general, and two case studies illustrate each of the overlay design procedures. Also included is the backcalculation of layer moduli from falling weight deflectometer data.
Mechanistically Based Flexible Overlay Design System for Idaho
Authors: Bayomy Fouad M. , Al-Kandari Fawzi A. , Smith Robert M.
Published: August 2018

A study was conducted on a mechanistically based overlay design procedure that incorporates the in situ pavement layer modulus values evaluated by deflection-based nondestructive testing using falling weight deflectometer data. The proposed overlay design procedure addresses the seasonal variation in the state of Idaho and adjusts the modulus values accordingly. The performance of the pavement is calculated in terms of critical strains based on the elastic multilayer theory. The study adopts the Asphalt Institute fatigue and rutting failure criteria to calculate the life of the pavement. Damage analysis is performed based on the past and expected future traffic to calculate the required overlay thickness. The procedure developed has been implemented in an event-driven, user-friendly computer program FLEXOLAY, which runs in the DOS environment. The program was tested and compared with other overlay design methods using pavement sections from the state of Idaho. The overlay thickness determined by FLEXOLAY was found to be close to some of the existing methods and far from others, depending on the existing pavement conditions.
Design of Flexible Pavements and Overlay Using an Expert System
Authors: Khedr Safwan A. , Mikhail Magdy
Published: August 2018

EXSPAV is an expert system program established for use in flexible pavement and overlay design. It helps transfer and facilitate the knowledge of experts and results of research and practice to the hands of the less experienced design engineer. It incorporates a versatile design approach, which also facilitates the prediction of the structural performance of pavements. EXSPAV was developed in the EXSYS environment and assimilates Ohio State University's predictive program of flexible pavement structural performance. It also has an overlay design module. EGYPAV is a knowledge-based pavement design program developed in the structure of EXSPAV. Its knowledge base was compiled through consultation with experts from the Roads and Bridges Authority, local universities, and construction companies. The base reflects experience, data, and research results for traffic, environmental conditions, pavements, and material characterization in Egypt. It also includes suggested designs of pavement structure for various combinations of design parameters. The program user may check the suggested design and find its structural performance through the inference engine–deterministic model interaction of the EGYPAV itself.
Effects of Asphalt Content and Air Void Content on Mix Fatigue and Stiffness
Authors: Harvey John T. , Tsai Bor-Wen
Published: August 2018

The primary objective of most procedures for asphalt concrete mix design is to find an asphalt content that minimizes the possibility of stability failure while providing adequate fatigue and other durability characteristics. To date, the consequences of asphalt content selection and construction compaction on fatigue performance and flexural stiffness have not been thoroughly investigated and documented with experimental data. The results of laboratory-controlled strain flexural beam testing, (i.e., fatigue life and flexural stiffness) for one aggregate and asphalt cement combination, five asphalt contents, and three air void contents are presented. The results clearly indicate the benefits of a lower air void content on both fatigue life and initial stiffness. Increased asphalt content was found to increase fatigue life and reduce stiffness. Alternative models for predicting fatigue life and initial stiffness using asphalt content, air void content, voids filled with bitumen, and the volume concentrations of asphalt and aggregate were evaluated. Elastic-layer theory was used to simulate the effects of air void content and asphalt content on the fatigue life of several example overlays using the models for stiffness and fatigue life from the laboratory testing. The simulations indicated an increase in predicted pavement fatigue life for lower air void contents and higher asphalt contents. Example simulations of the effects of increased asphalt content and decreased air void content at the bottom of thick overlays indicated a marked increase in predicted fatigue life. It was also concluded that stiffness should not be included in regression for fatigue life models for mix design unless there is a clear understanding of the effects of other variables in the model that correlate with both fatigue life and stiffness.
Effect of Segregation on Fatigue Performance of Asphalt Paving Mixtures
Authors: Khedaywi Taisir S. , White Thomas D.
Published: August 2018

The main objective of this research was to investigate the effect of segregation on fatigue performance of asphalt paving mixtures. Segregation in asphalt concrete pavements occurs when coarse material is concentrated in some areas of the pavement and fine materials in others. Segregation has been one problem that has resulted in poor performance in many pavements. Materials used in the study included gravel, natural sand, and an AC-20 asphalt cement. Aggregates were selected to meet the Indiana Department of Transportation specification for a No. 8 binder with a maximum aggregate size of 1 in. (25 mm). To simulate various levels of coarse and fine segregation, four artificially segregated mixtures were prepared in addition to the control asphalt mixture. Slabs were compacted for the five mixtures using the Purdue linear compactor. These slabs were cut into beams that were used to test for the fatigue properties of the five segregated asphalt concrete mixtures. Limits of fatigue were examined when flexural stiffness was one-third and one-half of the initial stiffness at 200 load applications. Results of the investigation indicated that the fatigue life of segregated asphalt concrete mixtures was significantly affected.
Asphalt-Rubber Overlay on Rubblized Concrete Pavement on I-135
Authors: Fager Glenn A.
Published: August 2018

During 1993 and 1994, the Kansas Department of Transportation constructed a 15.25-km full-depth asphalt-rubber project on I-135. Three test sections were finished in 1994 along with one control section in 1995. The test sections consisted of both a thick and thin asphalt-rubber section over rubblized portland cement concrete pavement (PCCP) and a completely reconstructed asphalt-rubber section. The control section was built over rubblized PCCP to the same thickness as the thick asphalt-rubber section. Approximately 172 000 metric tons of asphalt-rubber were produced using the wet (reacted) process. Data indicated that the asphalt-rubber mix cost approximately 50 percent more than the asphalt-only mix. Reducing the thickness of the asphalt-rubber from 225 mm to 180 mm would allow the cost to become equal to the asphalt-only control section. Equal performance of the reduced thickness section or longer performance from the 225-mm asphalt-rubber section would be a cost-effective method of using tire rubber in asphalt pavements. Test data indicate a stable mix and adequate thermal characteristics but high permeabilities. Performance after 6 winter months under traffic indicates no raveling, rutting, flushing, cracking, or moisture damage.
Asphalt Rideability: Construction Control with a Straightedge?
Authors: Hearne Thomas M. , Barbee Curtis L. , Helms Larry N.
Published: August 2018

Studies have indicated that the prime factor that influences the user's opinion of a road is longitudinal roughness. California profilographs are widely used for roughness control and are the foundation of many incentive/disincentive specifications. However, there is concern about how well this profilograph responds to the wavelengths of a pavement profile that are felt by highway users. A user's perception of ride quality is influenced by a combination of many factors, including speed, vehicle characteristics, and road profile. All roughness testing devices currently in use have limitations—particularly in providing rapid, meaningful results during construction. Wavelength and amplitude data are included from the roughest-riding sections of two resurfacing projects in North Carolina. Although the California profilograph is widely used for construction roughness control, the response of this device is very poor within the wavelength range found on these projects. If the disturbance wavelengths mainly responsible for causing rough rides fall within a narrow range, then an appropriate length straightedge, when provided with graphical capability, can provide a low-cost, simple, and practical means for controlling roughness during construction.
Hot-Mix Asphalt Segregation: Measurement and Effects
Authors: Williams R. Christopher , Duncan Gary , White Thomas D.
Published: August 2018

Segregation of hot-mix asphalt (HMA) has been associated with poor pavement performance. As a result, a nondestructive test method that could quickly identify segregation and be easily included in field testing would be useful to agencies. A study was conducted of four HMA mixtures with five levels of segregation. All levels of segregation for each mix were characterized by gradation, asphalt content, density, and air voids. The segregated mixes were tested with an air permeameter and a nuclear moisture/density gauge. In addition, thermal imaging equipment was field-tested on an existing pavement, at a hot-mix asphalt plant, and at a paving project to determine its overall effectiveness in detecting segregation. Preliminary wheel-tracking tests with the PURWheel tracking device were used to evaluate segregated mixture performance.
Control of Volumetric Properties of Hot-Mix Asphalt by Field Management
Authors: Kandhal Prithvi S. , Foo Kee Y. , D'Angelo John A.
Published: August 2018

Significant differences in the volumetric properties of laboratory-designed and plant-produced hot-mix asphalt (HMA) generally exist as demonstrated by FHWA Demonstration Project No. 74. The volumetric properties include voids in the mineral aggregate (VMA) and voids in the total mix (VTM). Guidelines for HMA contractors are needed to reconcile these differences and maintain control of volumetric properties during HMA production. The HMA mix design and field production test data (such as asphalt content, gradation, and volumetric properties) from 24 FHWA demonstration projects were entered into a data base and statistically analyzed. The objective was to identify and, if possible, quantify the independent variables (such as asphalt content and the percentages of material passing the No. 200 and other sieves) that significantly affect dependent variables VMA and VTM. The statistical analysis methods consisted of correlation analysis, stepwise multiple-variable analysis, and linear-regression analysis. On the basis of preceding work, guidelines have been developed for HMA contractors to reconcile the differences between the volumetric properties of the job mix formula and the produced HMA mix.
Issues Pertaining to Use of Superpave Gyratory Compactor
Authors: McGennis Robert B. , Anderson R. Michael , Perdomo Dario , Turner Pamela
Published: August 2018

Agencies, industry, academia, and others are rapidly implementing the products of the asphalt research portion of the Strategic Highway Research Program, products collectively referred to as Superpave. One of the principal products has been the Superpave gyratory compactor (SGC). The results of an experimental program, conducted at the Asphalt Institute Research Center in Lexington, Kentucky, and aimed at assessing the effect of various compaction parameters on SGC test results, are outlined. Compaction results were most often different when different mold diameters were used. The length of the laboratory short-term aging period also affected test results. Compaction temperature was a critical factor when a modified binder was used. SGC affected moisture-susceptibility test results although specimens fabricated using SGC were successfully demonstrated to predict moisture damage using the AASHTO T283 protocol. The experiment also compared the compaction characteristics of several different units. This comparison demonstrated minor to moderate differences in test results when the same mix was evaluated.
Portland Cement Concrete Pavement Texturing Methods
Authors: Ardani Ahmad
Published: August 2018

The testing and construction details of nine test sections with varying textural characteristics are described. The effects of the textures on the frictional and noise characteristics of the pavement surface were examined. Skid numbers were acquired according to ASTM E274 with ribbed and smooth tires at 65, 80, and 105 km/hr for all sections. Six types of texture-measuring devices were used to measure and compare the amount of texture in each section. To examine the noise properties of the test sections, noise data were required in three locations: inside the vehicle, 25 ft from the centerline, and near the right rear tire of the vehicle. The smooth tire showed more sensitivity to micro- and macrotexture than the ribbed tire, and longitudinal textures were quieter than transverse textures.
Reconstruction of Windsor Bridge Piers
Authors: Pierce Phillip C. , Mieczkowski Joseph J. , Gannon Edward J. , Korhonen Charles J.
Published: August 2018

The Windsor Bridge provides a two-lane highway crossing of the Susquehanna River in Broome County, New York. The structure comprises three 62.5-m (205-ft) simple-span through trusses supported by reinforced concrete abutments and solid-shaft piers. Having been built in 1935, it required rehabilitation in the early 1980s. The major effort included a deck replacement and complete structure repainting. What was expected to be relatively minor surface restoration of the foundation units became much more involved and complex. A coring program was initiated for predictions of the volume to be restored. The cores were petrographically examined and found to exhibit evidence of freeze-thaw damage and alkali-silica reactivity of the aggregate. The shafts, which were 2.13-m (7 ft) thick, were found to be delaminated from the freeze-thaw damage to depths of up to 610 mm (24 in.). An intensive evaluation of alternatives concluded that the most appropriate solution for this situation was to encapsulate the pier shaft with a concrete shell 305 mm (12 in.) thick with through-shaft posttensioning to retain the deteriorated existing concrete. This innovative solution is believed to be extremely unusual, if not unique, in the United States. Many unusual design-related issues were encountered while developing the plans for restoration. The background of the initial evaluation, development of alternatives, design philosophies, and general issues associated with the construction are presented. Thermosensor findings are also included, which yielded interesting and unexpected results. The knowledge gained from this project can be useful to other consultants and bridge owners.
Development of Prototype Performance-Related Specification for Concrete Pavements
Authors: Darter Michael I. , Hoerner Todd E. , Smith Kurt D. , Okamoto Paul A. , Kopac Peter A.
Published: August 2018

The development of a prototype performance-related specification (PRS) for concrete pavement construction is summarized. The prototype PRS requires that a pavement lot be divided into consistent sublots for the measurement of quality characteristics, which are then used to estimate future performance and life-cycle costs. The difference between the life-cycle costs of the target (as-designed) pavement and the actual (as-constructed) pavement lot is used to determine a rational pay adjustment. Both means and variations of all quality characteristics are directly considered in the pay factor determination. Extensive laboratory testing was conducted to determine material relationships needed in the prototype PRS. A Windows-based computer program, PaveSpec, was developed for use with the specification in simulation and in generating pay adjustments. However, additional work is required to make this a fully practical PRS.
Specification of Asphalt Concrete Using Total Quality Management Principles
Authors: Benson Paul E.
Published: August 2018

The application of total quality management principles to asphalt concrete specifications is discussed. Specifications from 16 states are reviewed, and their attributes are critiqued. Verification procedures, statistical compliance measures, tolerance limits, lot definition, point of acceptance, density determination, and pay adjustment methods are recommended. The innovative concepts of contractor rating systems and warranties are examined briefly.
Evaluation of Resilient Modulus of Cemented Lime Rock Base Materials in Florida
Authors: Ping W. Virgil , Ge Ling
Published: August 2018

The resilient modulus of pavement materials is an important parameter in pavement analysis and design. In recent years the emphasis of research has primarily been concentrated on investigating the resilient modulus of subgrade materials. Information is lacking on the resilient modulus of base materials for determining the properties of pavement layers. The results of field plate bearing load tests and laboratory resilient modulus tests on lime rock base materials are presented. Correlation relationships between the field layer modulus and the laboratory resilient modulus are evaluated. Comparison of the computed resilient modulus of the base layer with the layer modulus from the plate bearing load test under identical moisture and density conditions indicated a trend of increasing laboratory resilient modulus with increasing plate load modulus. The average values of the layer modulus backcalculated from the plate bearing load tests were higher than those of the computed equivalent resilient modulus from the laboratory tests with the averaged applied stresses in the elastic range.
Engineering Behavior of Lime-Treated Louisiana Subgrade Soil
Authors: Puppala Anand J. , Mohammad Louay N. , Allen Aaron
Published: August 2018

Lime stabilization is often used to treat subgrade soils when they are soft and cohesive in nature. A study was conducted to investigate the engineering behavior, including the resilient and strength behaviors, of a lime-treated subgrade soil. The lime treatment procedure was adapted from the specifications of the Louisiana Department of Transportation and Development. Silty clay, a soil often found in Louisiana subgrades, is used as a base soil. A summary of various engineering properties of a lime-treated soil from resilient modulus, unconfined compression strength, and California bearing ratio (CBR) tests conducted at five moisture content and dry density levels is provided. Tests were also performed on the raw soil without lime treatment, and these results were compared with those of tests with the lime-treated soil. The comparisons indicate that the present lime treatment method results in an increase in strength and resilient modulus properties and a decrease in plasticity characteristics and plastic strains. A regression model with three constants was used to analyze the resilient modulus test results. The model constants are presented as functions of soil properties. Resilient modulus correlations that use either CBR or unconfined compression strength, moisture content, dry density, degree of compaction, and stresses as dependent attributes are developed.
Resilient Modulus Testing of Lean Emulsified Bases
Authors: Farrar Michael J. , Ksaibati Khaled
Published: August 2018

A research study conducted jointly by the Wyoming Department of Transportation and the University of Wyoming examined the effect of low emulsified base treatment on resilient modulus values. The study involved selecting two types of aggregate, treating duplicate samples with variable amounts of emulsified asphalt, and performing resilient modulus tests on the samples at various ages. Data were then analyzed to evaluate the variations in resilient modulus values due to the changes in testing time or percentage of emulsified asphalt added. The following conclusions were reached: resilient modulus testing can be used to evaluate emulsified asphalt–treated bases; aging samples before testing will cause a substantial difference in resilient modulus values; and low percentages of emulsion treatments increase resilient modulus.
Effectiveness of Various Sludge Stabilization and Solidification Methods
Authors: Chang Dave Ta-Teh , Liao Wen-ping , Chen Shin-yueh
Published: August 2018

If sludge contaminated with heavy metals is not properly treated, water flowing over the sludge can cause the heavy metals in it to leach out, polluting groundwater. To establish an effective means of dealing with this problem, the engineering applicability and stability of sludge solidified using portland cement (A1), a gypsum-type agent (B1), a cement Type I agent (A2), and a cement Type II agent (B2) were studied. The sludge was obtained from Keelung River. After the treated sludge had cured for 7, 14, 28, and 60 days, each sample was tested to ascertain its compressive strength and the rate at which six different hazardous heavy metals leached out. This was done to evaluate the feasibility of sludge solidification. The findings indicate that the ratio at which the solidifying agent is used determines the strength of the treated sludge. No significant improvement was found when the treatment agent was used at rates of less than 10 percent. Except for the A1 agent, marked improvement was observed for all types of solidifying agents except when the amount of additive was increased to 20 percent. The heavy-metal leaching rate of treated specimens met the requirements of the pollution control regulations, indicating that hazardous heavy metals had been effectively fixed within the sludge. Therefore, solidifying agents comprise an effective and feasible method of solidifying and stabilizing Keelung riverbed sludge.