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This paper describes the contribution made by road construction in the area of energy consumption and greenhouse gas emissions. The road construction techniques analyzed include hot asphalt mixes, cold emulsion mixes, concrete pavements and in-place or plant recycling. The entire production and construction process is evaluated from materials manufacture, placement and maintenance works during a 30 year service life.

For rehabilitation, in-place recycling using emulsified asphalt with or without cement consumes the least energy and the least greenhouse gas.

PennDOT performed a literature review, survey of other states, and a cost benefit analysis of multiple thin surface treatments, and finds that the equivalent annual cost of micro surfacing is 44% lower than that of thin overlay and can provide 6-8 years of service life when applied at optimal times. PennDOT also recommends the consideration of expanded use of micro surfacing, from both a geographical and traffic level point of view.

This report summarizes the state-of-the-art and current state-of-the-practice of crack treatments and concludes with current best practices. This report is limited to crack sealing and crack filling of asphalt pavements, and does not consider joint filling on concrete pavements, reflective cracking retardation techniques, joint construction techniques, or other related issues.

Miller Paving Limited’s Double Surface Treatment with Stress Absorbing Membrane Interlayer (SAMI) on Old Homestead Road in York Region, was completed over a 3-week period in July-August 2015. This project provided a cost effective and environmentally friendly alternative to a major road reconstruction and is a great example of using the correct treatment on the correct road at the correct time.

The objective of this study is to determine if the scrub seal is more cost effective than microsurfacing, chip seals and the 1" hot mix overlay. Scrub seals were placed at 10 different locations and reviews of each section were made to determine the usefulness of the seal. Most of the scrub seals are very promising although it has been determined they should be limited to areas of less than 7500 ADT. Most of these scrub seals are about 1 year old and we are hoping to get a life span of 3 to 4 years from them.

A 1-year research project was sponsored by TxDOT and conducted by University of Texas at Austin researchers to evaluate the Cape seal process as a pavement rehabilitation technique.  During the course of this research project, most of the Cape seal projects that have been constructed within the state were visited as part of the evaluation.  Projects documented during the visits included both successes and failures.

This paper is a review of the Ministry of Transportation of British Columbia’s successful experience with HIR and describes the evolution of the program over a 25-year history. The paper documents the evolution of the program that has led to an increased service life of HIR at a cost of approximately 50% less than conventional mill and fill with an estimated 30 to 40 percent reduction in greenhouses gasses. The paper describes changes to project selection criteria, preconstruction sampling and testing requirements and construction specifications that are responsible for the successful HIR program in British Columbia.

The primary objective of this project was to develop a test for measuring the bond strength between pavement layers. The research was also to evaluate tack coat materials and application rates for the Alabama Department of Transportation (ALDOT).

This Technical Brief provides an overview of tack coats and their vital role bonding multiple asphalt layers into one monolithic system. Poor tack coat techniques result in compromised bonding of the asphalt layers. This leads to pavement distresses. Possible slippage cracking and delamination are associated with poor bonding. Additionally, poor bonding can lead to structural distresses, namely fatigue cracking and potholes. Often this lack of sufficient bonding is not recognized as the source of failures. 

Find the full report here.

Asphalt tack coat is a light application of asphalt, usually asphalt diluted with water. It is used to ensure a bond between the surface being paved and the overlying course. Normally, hot asphalt cements, emulsified asphalts, or cutback asphalts are used as tack coats. The objective of this study was to evaluate the practice of using tack coats through controlled laboratory simple shear tests and determine the optimum application rate.

See Report Here.

This is the final report for NCHRP 9-62 where the authors developed a short pin raveling test to determine when a CCPR pavement has sufficiently cured to allow opening to traffic and a long pin test to determine when the pavement has cured sufficiently to place the wearing surface. The authors have recommended additional field verification of the proposed test methods and threshold values.

Curry County saves their river road in shady, cool conditions thanks to the next evolution in Chip and Fog Seal Treatments.

University of Illinois study that examined CIR, FDR and HMA. Study concluded/recommended that CIR and FDR with asphalt products be considered "standard procedures."

The Virginia Transportation Research Council performed a laboratory investigation to evaluate whether stockpiling a CCPR mixture using foamed asphalt and cement as an active filler had any negative consequences with respect to the mechanical properties of the mixture. The mechanical properties included indirect tensile strength and dynamic modulus. The study recommended allowing stockpiling of CCPR mixtures using foamed asphalt and cement as the active filler for up to 24 hours. The study recommended verification of the findings and recommendations through follow-up studies.

VDOT study evaluating the performance of preventive maintenance treatment alternatives to hot mix overlay show a FiberMat and microsurfacing cape seal performed well with very little reflective cracking.

This report evaluated three test sites, located in Galesburg and Machesney Park, Illinois, and Dyer, Indiana, that were HIR treated and evaluated in-situ and in the lab. Physical and rheological properties of binder recovered from each site were obtained. Interaction plots, combining rut depth from the wheel track test (WTT) and flexibility index (FI) from the Illinois Flexibility Index Test (I-FIT), were in agreement with binder test results. Falling weight deflectometer and roughness measurements were conducted before and after HIR. The environmental assessment showed a difference in energy usage and GHGs of 3.9–17.6% and 1.3–19.2%, respectively, between a HIR process with 38 mm AC overlay and a corresponding traditional 50 mm mill and AC OL for different plant locations. Energy savings from using HIR treatments heavily depend on the surface treatment after HIR, thickness of overlay (if overlay is chosen as the surface treatment), and hauling distances for plant-produced materials needed for overlays. 

The study examined a test section built in 2002 and a control section in 2003 to compare the cost and performance of HIR with conventional milling and resurfacing. After 8 years, in-service data were used to draw some conclusions. The test and control sections performed well. The HIR section was built at less than half the cost of the conventional section. Projections showed that HIR was cost-effective and would save 40% more than the conventional method of pavement rehabilitation.

Full Depth Reclamation & CCPR allowed INDOT to repair and upgrade a major collector in Northeast Indiana. State Route 101 appeared to need surface repairs, but upon further investigation, a deeper treatment was needed in order to restore the roadway and create a safer route for both the local Amish traffic and regular vehicular traffic.

In 2008, Tennessee DOT awarded $12-million worth of contracts for micro surfacing 500 miles of roads. 

Comparison of the environmental benefits of CIR with a thin HMA overlay to mill and overlay for 9 resurfacing projects in Wisconsin. Results showed average environmental savings of 23% in energy consumption and carbon dioxide emissions, 20% reduction in water consumption and reduced virgin aggregate consumption of 37% when using CIR with a thin HMA overlay instead of a comparable mill and overlay.

This report fully documents the research findings from the NCHRP 9-51 study determining material properties for cold-recycled asphalt mixtures for input to structural design and analysis programs and suggested Level 3 dynamic modulus values for these materials for use in pavement structural analysis using Pavement ME Design.

Louisiana Dept. of Transportation and Development awarded a $2.25-million contract for improvements to Vance Brothers for 17.5-miles of US84 and LA Rte. 28 in Catahoula and LaSalle Parishes, with micro surfacing specified as the wearing course for most of the route. 

This paper is a summary of the sustainability benefits derived from two in-place recycled pavements in Virginia that used CIR, CCPR and FDR. The paper reports cost savings, reduced construction times and reductions in green house gasses and energy consumption for projects on I-81 and I-64.

Trumbull County, Ohio was successfully preserving its road network, primarily with Chip Seals.  However, public perception was that the roads needed to be black to be good.  Without the necessary funding for a large hot mix overlay program, county managers decided to implement a fog seal program.  Six months after applying the chip seal, they fog sealed the recently treated roads.  The roads got a extra measure of preservation from oxidation, got an extra measure of stone retention properties and they looked aestetically pleasing to the taxpayers.

This study evaluated the effect of emulsion content reduction during the CIR process in the field on mix properties. Three laboratory CIR mix designs were performed using the same RAP material and emulsion at three different mixing temperatures. The mix design results showed that as the mixing temperature increased, the optimum emulsion content decreased significantly. Also, increasing the mixing temperature improved the mixture compaction. Both the dry and retained stabilities were also higher for the high-temperature mixtures. The critical low temperatures of high-temperature mixtures were higher than the room-temperature mixture (indicative of a worse performance) but still lower than the -20°C requirement. From the results of this study, it appears that reducing the emulsion content of CIR mixtures during the heat of the day does not necessarily deteriorate mixture properties. This could result in substantial savings for agencies that use this process without sacrificing long-term performance.

This paper is a summary of the sustainability benefits derived from two in-place recycled pavements in Virginia that used FDR, CIR and CCPR. The paper reports cost savings, reduced construction times and reductions in green house gasses and energy consumption for projects on I-81 and I-64.

In 2005, the Georgia Department of Transportation (GDOT) moved away from chip seal treatments due to vehicle damage caused by loose stone and friction loss due to bleeding. Recently, however, GDOT sought to bring the process back by changing both the construction methods and the materials used. The GDOT Maintenance Department determined that a pilot project, called a triple chip seal, would be the most appropriate way to test the new approach. 

Louisiana’s US Route 84 was suffering from extensive pavement wheel path rutting and shoving. To correct the problem, the Louisiana Department of Transportation and Development (LADOTD) provided a budget of $2.25 million to execute repairs for the 17.5-mile length of road. 

The stretch of Utah SR 36 that runs through Tooele between 3 O’Clock Drive and CR 2000 North, had actually been reconstructed with HMA in 2015-2016. The road was completely torn out and replaced; new utilities and curb and gutter were also constructed as part of the project. But the HMA placed on the roadway allowed water to permeate between two separate layers of asphalt.  Heavy snow or rain storms would drain into the first layer of asphalt, then into utilities, such as manhole concrete pipe, causing the manholes to flood. Within less than two years, the road needed to be sealed against water. UDOT and Tooele’s elected officials considered several preservation methods, including slurry seal and chip seal, but ultimately, because of the large numbers of vehicles traveling SR 36, the group chose to micro surface the pavement in the summer/fall of 2017 before winter could set in.

In order to keep residents satisfied and to attract industry, DeSoto County proactively treats their roads to maintain high quality trasportation infrastructure for a fraction of what it would cost to wait until more expensive repairs are needed.  Safety of the network is improved as well.

Application on high-speed pavement with significant life extension, and millions saved in taxpayer dollars. 

In Limerick Township, 30 miles outside Philadelphia-- one thing is clear—the Township takes their pavement preservation seriously.

As impressive, is the municipality's fundamental understanding that “mill & fill” is not as cost effective as pavement preservation—so much so that they are able to move most needed paving operations in-house. 

The use of micro surfacing results in 54% less energy usage, 35% less raw material usage, 44% less green house gas release, and a 28% reduction in life cycle cost compared to a traditional 2 inch mill and fill treatment.

Hot in-place recycling helps the combined City and County of Denver meet its sustainability goals while lowering energy requirements and extending pavement life. The City of Denver is increasing its use of hot in-place recycling in order to meet their own sustainability criteria, in terms of the amount of material recycled, and cumulative emissions as opposed to other conventional maintenance methods.  

Using Optimized Solutions for Extreme Soil Conditions

Sometimes field changes are necessary.  The importance of utilizing test strips prior to starting a project cannot be understated.  

This study was centered on elucidating the chemical reactions that bring about soil stabilization and modification.  It has been established that the chemical compounds found in soil; quartz, feldspar, dolomite, calcite, montmorillonite, kaolinite etc. react with the chemical constituents found in different identified chemical stabilizers. This research work will better place designers, constructors and researcher on the choice of soil chemical stabilizer and techniques and the extent of chemical reactions that take place during soil chemical stabilization. 
 

No VOC Penetrating Emulsion Prime Coat, ePrime, contains no added solvents.  The PEP penetrated the surface within 15 minutes and withstood a garbage truck that drove through the work zone.

This paper is a summary of the sustainability benefits derived from two in-place recycled pavements in Virginia that used CCPR, CIR and FDR. The paper reports cost savings, reduced construction times and reductions in green house gasses and energy consumption for projects on I-81 and I-64.

Cold Central Plant Recycling allowed INDOT to repair and upgrade a major collector in Northeast Indiana. State Route 101 appeared to need surface repairs, but upon further investigation, a deeper treatment was needed in order to restore the roadway and create a safer route for both the local Amish traffic and regular vehicular traffic.

This project won a Recycling Award from Roads and Bridges Magazine in 2019. See the link below or the February 2019 Issue for the article.

Contractor successfully repaired Lake Louise Marie Road in the Town of Thompson located in Sullivan County New York.  Fiber reinforced interlayer with a Paver Placed Surface Treament overlay. 

Mass cracking of roadways in Yuma County, AZ, had become so severe, they required immediate attention. After evaluating all of the options and taking budget constraints into consideration, a rejuvenating chip seal was chosen as the best solution to the challenge.

Sylvania, OH is using micro surfacing to save money when resurfacing streets.  They expect 8 - 12 years of life extension with micro surfacing, costing 35 cents on the dollar compared to asphalt mill and repair.

Micro surfacing was successfully placed on one of the busiest and most congested roads in the Greater Columbus area. By working with the Ohio DOT, the contractor was able to minimize traffic disruption while placing a high quality material.

This synthesis report provides an overview of successful chip seal practices in the United States, Canada, and overseas. Although not meant to be an exhaustive study, it covers the spectrum of chip seal practice and presents, where possible, the state of the art, as reported in the literature and survey responses. The report presents ways to assist in the development and implementation of pavement preservation programs by identifying the benefits of using chip seal as part of a preventive maintenance program. Innovative and advanced chip seal programs from around the world were identified with respect to critical factors that can be incorporated by other transportation agencies. Approximately 40 best practices were identified in the areas of chip seal design methods, contract administration, equipment practices, construction practices, and performance measures. The increased use of chip seals for maintenance can be a successful, cost-effective way of using preventive maintenance to preserve both low-volume and higher-volume pavements.

The City of Bay Village leverages a standardized pavement management program, allowing them to deploy their crack seal treatments to the right roadways, and at the right time. Through this effort, the City has been able to extend the life of these roadways an average of 4 years, while maintaining an above-average network condition of 74.

• Significant cost savings can be achieved by organizing pavement preservation work so that the contractor will have several weeks of work in one geographic area.
• Delaying pavement preservation by applying a treatment on an existing pavement with a PCI of 60 instead of 80 will result in an increase in equivalent annual treatment costs between about 70 to 100%.
• Delaying the application of the treatment to an existing pavement condition of 40 will result in an increase in the equivalent annual treatment cost of about 300%.

This is an educational document containing instructions and examinations.  It discusses basic procedures for prime coat application, distributor operations, inspection, and documentation. This is of particular value for construction inspectors.

TRB’s National Cooperative Highway Research Program (NCHRP) Report 712: Optimization of Tack Coat for HMA Placement presents proposed test methods for measuring the quality and performance characteristics of tack coat in the laboratory and the field, and includes a training manual presenting proposed construction and testing procedures for tack coat materials.

It is available for Purchase as a PDF from TRB here.

A comprehensive guideline for prime coat use. A prime coat and tack coat guide publication for project development and field personnel to provide decision-making guidance on how to use, when to require, and when to eliminate prime and tack coats.

Following damage that appeared on the surface layers (fatigue cracks, peeling, rapid structural fatigue), the IBEF International Bitumen Emulsion Federation launched a survey in 1998. The goal of the survey was to assess the current situation of this technique worldwide by studying the practices, proportions and specifications that exist.

Find full report here.

The constructability review of surface treatments on base courses.  It contributes to the development of a surface treatment design and construction guide, updates to the TxDOT surface treatment training manual, and updated specifications.

The main objective of this research project was to evaluate the effectiveness of prime coats and determine which combinations of methods and materials provide the most benefit to TxDOT.  The use of prime coats are described, and their construction requirements are discussed in Item 310 of the Texas Department of Transportation (TxDOT) Standard Specifications. 

Two alternative detailed guidelines for incorporating mixing-grade emulsified asphalt into the uppermost layer of base course.  

"Stabilization projects are almost always site-specific, requiring the application of standard test methods, along with fundamental analysis and design procedures, to develop an acceptable solution. As with any such process, adherence to strict environmental constraints is vital to project success. The use of cementitious materials makes a positive contribution to economic and resource sustainability because it allows enhancement of both standard and substandard in situ soils to levels consistent with the requirements of a given application."

Micro surfacing is an effective surface treatment to prolong the life span of paved roads by preserving or improving the condition of paved roads. Whether used as a preventative treatment, corrective treatment, or holding strategy, micro surfacing lowers pavement life-cycle costs. 

"This study concluded that the improvements to key properties of cold mix by the addition of Portland Cement can be explained by a range of mechanisms, including improved rate of emulsion coalescence after compaction, cement hydration and enhancement of binder viscosity."

An evaulation of Texas roads provided surprising results when the best friction numbers came from a 10-year-old microsurfacing project. So when TxDOt had a new project that involved maximizing friction on a high traffic road (1-10 in Crockett County) they chose microsurfacing because it can yield greater long-term friction results throughout its service than an ultra thin lift overlay, and at a lower cost.

The researchers found that, in most cases, the extra energy embodied in the cool material was far greater than the energy savings from increasing the albedo. 

“Over the life cycle of the pavement, the pavement material matters substantially more than the pavement reflectance,” - Ronnen Levinson of Berkeley Lab.

“I was surprised to find that over 50 years, maintaining a reflective coating would require over six times as much energy as a slurry seal. The slurry seal is only rock and asphalt, which requires little energy to produce, while the reflective coating contains energy-intensive polymer.” - Ronnen Levinson of Berkeley Lab.

Read full source here. 

"The Federal Aviation Administration requires the use of stabilized bases for all pavements that will be required to support aircraft weighing 45,350 kg (100,000 lbs) or more. literature review was performed to determine the current state of the art in terms of understanding stabilization mechanisms, design procedures, and considerations. were collected to provide a review of the performance of many pavements at high-volume airports that support heavy aircraft loads. Field data collected included structural data in the form of nondestructive testing (NDT) performed with a falling weight deflectometer, visual condition survey using the pavement condition index (PCI) procedure, and construction and maintenance history data. The NDT was evaluated to determine modulus values for the various pavement layers. he PCI data were compared to historic PCI data to determine trends in performance. he construction and maintenance history records were reviewed to determine rehabilitation efforts required to maintain the pavements at appropriate levels."

"Complete excavation of frost-susceptible material is not economically viable in all cases. Emulsion mixes have been used successfully to follow roadbed soil movement without cracking. Laboratory and field observations indicate that emulsion mixes have membrane-like mechanical properties rather than the slab-like properties of standard hot bituminous mixtures. Furthermore, emulsion mixes are not as susceptible to thermal cracking as regular standard hot bituminous mixtures." 

Stabilized road gravel was tested to compare with that of unaltered raod gravel. " California bearing ratio (CBR), resilient modulus (M_r) , and unconfined compression (q_u) tests were conducted on road surface gravel alone and the fly-ash stabilized road surface gravel samples prepared in the field to evaluate how addition of fly ash improved strength and stiffness.  After 7 days of curing, the stabilized road surface gravel compacted in the field from a field-mix sample had CBR ranging between 48 and 90, M_r between 96 and 125 MPa, and q_u between 197 and 812 kPa, whereas the road surface gravel alone had CBR of 24, and M_r of 51 Mpa."

The Strategic Highway Research Program (SHRP) H-106 maintenance experiment and the Federal Highway Administration (FHWA) Long-Term Monitoring (LTM) of Pavement Maintenance Materials Test Sites project studied the treatment (sealing and filling) of cracks in asphalt-surfaced pavements. Many different treatment materials and methods were investigated between 1991 and 1998 through test sites installed at five locations in the United States and Canada. The findings of these combined studies have been merged with standard highway agency procedures to provide the most useful and up-to-date information on the practice of asphalt crack treatment.

This Manual of Practice is an updated version of the 1993 SHRP Crack Sealing and Filling Manual. It contains the latest information pertaining to the performance of treatment materials and methods, the availability and relative costs of sealant/filler materials, and the proper ways of planning, designing, constructing, and monitoring the performance of crack treatment projects. It also provides an updated partial listing of material and equipment manufacturers. 

This Manual is intended for field and office personnel within highway maintenance agencies and contracted maintenance firms.  It contains valuable information for supervisors and foremen in charge of individual crack treatment operations, engineers in charge of planning and overseeing many crack treatment projects, and managers in charge of establishing crack treatment policies and standards.

On June 18 and 19, 2007, Caltrans District 9 (D9) placed six rejuvenator seal test sections to preserve a  section in the eastbound number two lane ( right lane), often used by trucks, on  Highway 58 between PM 123.3 and 125.1 east of Mojave, California in Kern County .  This roadway is 4-lane divided freeway with a 65 MPH speed limit.  The weather during the application was dry with light winds.  

The California skid test (CT372) and ASTM E274 locked wheel skid trailer were used to evaluate friction before and after treatment application. Two of the 6 treatments (CRF and Reclamite) were sanded after application to blot excess emulsion. The skid numbers dropped about 30 % after the application of the treatments. 

Cores were obtained before and after treatments to determine if the rejuvenators softened the upper millimeters of existing pavement.  The bending beam rheometer (BBR) stiffness and m-value testing showed the CRF and PASS-QB products softened the existing pavement; however, this finding is unexpected based on previous experience by the monitoring team.  The CQS-1h emulsion significantly increased the stiffness of the pavement. The dynamic shear rheometer (DSR) test method was too variable (coefficient of variation of about 50%) to determine if there was any statistical difference between the treatments and the control sections.

In the summer of 2011, a follow-up survey was completed and additional testing conducted. The results of the survey showed that the treatments have improved the performance compared to the control with some treatments softening the existing pavement more than others

This is the initial phase of further planned testing. Conclusions cannot be drawn until further work is done and the remaining test sections are completed.

The use of preservation seals on asphalt pavements is a crucial part of any effective pavement management program. It is important to optimize the use of available budgets to extend the life of our pavements as much as possible. The nation’s highway system is one of our most valuable assets.

Analysis of the performance of surface treatments on Utah pavements indicates that Open Graded Surface Courses (OGSC) have an average life, based on skid resistance of almost 9 years and that Chip Seal Courses (CSC) have a significantly longer life.

Out of all the factors analyzed, traffic has the most significant effect on the performance of the treatment. Factors such as aggregate source and asphalt supplier were also investigated but lack of data prevented from reaching any significant conclusion.

Based on the relative cost of both treatments and the performance observed through this study, it is recommended that Utah Department of Transportation expand the use of CSC to certain roads with AADTs up to 20,000 vehicles and continue the existing procedure of using CSC in highway sections with AADTs below 5,000. It is also recommended that UDOT modified the existing policies and limit the use of OGSC where the running speeds are 55 mph or greater and AADTs are in excess of 25,000 vehicles. Medium volume facilities (5,000 to 25,000 AADT) should be sealed with treatments new to UDOT but proven in other states.

An initial cost analysis showed that the implementation of the changes suggested as part of this report will results in savings of over $2 million per year in the maintenance budget. Thus allowing for better use of resources while still serving the traveling public.

This report presents the results of a research study funded by SOLARIS University Transportation Center. The research evaluated the long-term performance of cape seals with micro surfacing and slurry seal in the Truckee Meadows and Incline Village areas of Northern Nevada.

Recently, use of pavement preservation technologies, such as bituminous seal treatments, has increased. Seal treatments are often used to rejuvenate aged asphalt pavements and can decrease permeability and retard oxidation, cracking, and raveling. Many factors affect rejuvenation, and current specifications governing how rejuvenation is characterized could be enhanced. Viscosity testing of asphalt binder extracted and recovered from a pavement’s near surface is the predominant means of characterizing rejuvenation (e.g., a product must reduce viscosity by 40% to be classified as a rejuvenator).  This paper presents data that suggest other rejuvenation approaches are worth considering because (a) extraction and recovery can adversely affect viscosity results, (b) viscosity testing cannot be conducted without forced and unrealistic blending of aged binder and rejuvenator, (c) high test temperatures may not be the most informative for distresses of interest (e.g., cracking), and (d) viscosity could not detect rejuvenation behaviors of some proprietary products.

This document provides detail on guidelines and best practices on Bonded Wearing Course from Caltrans

This report documents the current state of the practice and research efforts on the use of thin asphalt concrete overlays for pavement maintenance, rehabilitation, and preservation.  This synthesis was performed by conducting a literature review, including both U.S. and international technologies, as well as a survey of state departments of transportation (DOTs) and selected local agencies. Information was also gathered from selected individuals and private industry representatives.

Micro surfacing can be expected to provide an average service life of 7 years if the underlying road is in good condition.

Micro surfacing provides good friction characteristics for up to nine years of service.

Micro surfacing is a pavement preservation and maintenance tool with very few technical or operational limitations.

Fog seal increases pavement life and postpones major rehabilitation. The reduction of permeability due to fog sealing will reduce moisture induced damage, but this benefit comes with a temporary loss of surface friction. However, quantifying the effectiveness of fog seal by measuring the permeability is a difficult task. While fog seal may be a good low-cost maintenance option for low volume roads, the rate of recovery of the friction may be very slow due to less rubbing action between fog sealed surface and tire. Four low volume parish roads in Caddo parish, LA have been selected for this study. Two emulsions, namely CSS-1H and E-fog, with three different application rates, were used to evaluate the reduction in hydraulic conductivity and to assess the characteristics of friction over time. Results show that fog seal is expected to be fully cured within 2.5 to 3.5 hours for 0.2-0.4 gal/yd2 application rate. The same field-cores were tested before and after fog sealing to exactly quantify the reduction in hydraulic conductivity. It was observed that fog seal has significant potential to reduce the hydraulic conductivity. Considering all four pavements and application rates of 0.1-0.22 gal/yd2, the average reduction in hydraulic conductivity was 38.5%. Reduction in hydraulic conductivity shows very slight sensitivity to the application rate. Irrespective of road type, emulsion and application rate, fog seal causes a sudden drop in the International Friction Index parameter F60 by 20 to 40%. Fog sealed surface does not return to the original level of friction after three months, however, the rate of recovery was the highest for the busiest of the observed Caddo parish roads.

As part of the NCAT-MnROAD Pavement Preservation Group (PG) Study, six micro surfacing test sections were placed on Lee County Road 159, a low traffic volume road located in Auburn, Alabama. NCAT found the sections treated with micro surfacing show improved performance compared to the control sections and have been effective in extending pavement life.

The Town of Fairfield saves their network using micro surfacing as the primary backbone of a robust pavement preservation program.

Progressive agencies are constantly seeking the most cost effective methods to improve ride quality and decrease cracking as part of their overall pavement management strategy. More and more agencies like MnDOT are finding the use of micro-milling and high performance micro surfacing mixes to be worthwhile investments of their limited funding.

Base Stabilization was selected for its efficiency and cost savings over total removal and replacement.  Problems with failing pavement layers, but not deep subgrade issues, made their parking lot a perfect candidate for Base Stabilization.   

  The purpose of this study was to explore the effectiveness of chemical stabilization practices on unpaved roads.  A 550-ft-long segment of Hurley Lane, a gravel road in Loudoun County, was selected for testing.  The construction technique known as full-depth reclamation (FDR) was used.  The existing unpaved road section was pulverized to a depth of 12 in and subsequently blended with 5% cement by weight using road reclaiming equipment.  The surface was then covered with a double chip seal.  The main objective of this project was to provide stability while still maintaining the appearance and “feel” of a gravel road.
 

Arizona studies 17 CIR projects constructed from 1981 to 2001, finds improved IRI, better resistance to cracking, lower post-construction maintenance costs, and “significant improvements in performance.”

Study examines 24 CIR asphalt roads constructed in Iowa from 1986 to 2004. Research finds that sample roads with good subgrade support have 36% longer service lives than roads with poor subgrade support in addition to revelations in varying factors affecting performance in CIR between high and low traffic roads.

University of Illinois study that examined CIR, FDR and HMA projects. Study concluded/recommended CIR and FDR with Asphalt Products be considered a “standard procedures.”

FHWA report includes summary of performance seen by multiple agencies, confirms CIR has better results than mill & fill; And the same or longer pavement life, with equal or lower NPV than conventional HMA. Report recommends an AASHTO structural layer coefficient of 0.32-0.34 for CIR mixes.

For years, the Town of Lexington, Massachusetts had maintained its streets with a program that consisted of mill and overlay and reclamation, along with crack sealing as necessary. But Town Engineer John Livsey has never been a fan of letting roads go until they need major repair, and over the past five years, his team has introduced a number of pavement preservation techniques into its overall program, including micro surfacing and fog sealing. In August 2016, the Town initiated cape sealing, testing the technique on one street with 21,867 square yards of treatment.

When cities turn to implementing a pavement preservation plan, the life of the pavement can be significantly extended.  To ensure a quality project, the contractor must prepare the streets and project properly, use proper application techniques, and manage traffic properly.

The Lewisville Fire Department needed to rehabilitate the asphalt paved areas and expand the parking lot of its fire house. By electing to use the Full Depth Reclamation (FDR) process, the department saved time, money and transformed the deteriorated parking area into one that will last for years to come!

Project location, type of distresses and traffic volumes led Utah Department of Transportation (UDOT) to pick Cold In-Place Recycling (CIR) for this project. A well tested mix design was key to success.

This project won the Roads and Bridges magazine asphalt recycling award for 2018. (See February 2019 Issue, or the link below for full story)

Washington Ave. in Las Vegas, Neveda was distresses such that reconstruction was needed. The existing pavement consisted of 4.5 to 7 inches of asphalt pavement over 13.5 to 18.5 inches of granular base. The conventional design would have consisted of removal of the asphalt and base material and replacement with 18 inches of granular base and 6 inches of asphalt. An alternative method was selected using base stabilization with emulsified asphalt. The alternate design consisted of removal of the asphalt pavement and in-place stabilization with 5% emulsified asphalt of the upper 6 inches of the existing base followed by 5 inches of new asphalt. The alternate design saved the city an estimated $323,000, a 30% savings. Construction days were reduced from an estimated 120 days to 40 days and 3,000 fewer loads of materials were trucked on and off the project.

NIMC erases $38,000 change order and improves strength of it’s new entrance road with Soil Stabilization.

California extends the life of one of their most traveled highways, with minimal impact to traveling public and 78% cost savings using type III slurry seal & crack seal.   

Progressive agencies are constantly seeking the most cost effective methods to improve ride quality and decrease cracking as part of their overall pavement management strategy. More and more agencies like MnDOT are finding the use of micro-milling and high performance micro surfacing mixes to be worthwhile investments of their limited funding.

This report fully documents the research findings from the NCHRP 9-51 study determining material properties for cold-recycled asphalt mixtures for input to structural design and analysis programs and suggested Level 3 dynamic modulus values for these materials for use in pavement structural analysis using Pavement ME Design.

This report fully documents the research findings from the NCHRP 9-51 study determining material properties for cold-recycled asphalt mixtures for input to structural design and analysis programs and suggested Level 3 dynamic modulus values for these materials for use in pavement structural analysis using Pavement ME Design.

During the 2011 construction season, the Virginia Department of Transportation (VDOT) completed an in-place pavement recycling project to rehabilitate a 3.66-mile section of pavement on I-81 near Staunton, Virginia. VDOT employed three in-place pavement recycling techniques, full-depth reclamation (FDR), cold in-place recycling (CIR), and cold central-plant recycling (CCPR). Materials for both the CIR and CCPR were produced using foamed asphalt with cement as an additive. A combination of cement and lime kiln dust was chosen for the FDR process.

From the results of this study, the combined structural layer coefficient for the CCPR and FDR materials was calculated as 0.37. The structural layer coefficient for the CIR material was calculated as 0.39. The structural layer coefficient for the CCPR material was calculated to have a likely range of 0.37 to 0.44. Laboratory testing showed that the performance of the CCPR and CIR materials is expected to be similar. The field performance tests demonstrated that the section of pavement rehabilitated by the three in-place recycling methods continues to perform well after nearly 3 years of high-volume interstate traffic.

During the 2011 construction season, the Virginia Department of Transportation (VDOT) completed an in-place pavement recycling project to rehabilitate a 3.66-mile section of pavement on I-81 near Staunton, Virginia. VDOT employed three in-place pavement recycling techniques, full-depth reclamation (FDR), cold in-place recycling (CIR), and cold central-plant recycling (CCPR). Materials for both the CIR and CCPR were produced using foamed asphalt with cement as an additive. A combination of cement and lime kiln dust was chosen for the FDR process.

 From the results of this study, the combined structural layer coefficient for the CCPR and FDR materials was calculated as 0.37. The structural layer coefficient for the CIR material was calculated as 0.39. The structural layer coefficient for the CCPR material was calculated to have a likely range of 0.37 to 0.44. Laboratory testing showed that the performance of the CCPR and CIR materials is expected to be similar. The field performance tests demonstrated that the section of pavement rehabilitated by the three in-place recycling methods continues to perform well after nearly 3 years of high-volume interstate traffic.

During the 2011 construction season, the Virginia Department of Transportation (VDOT) completed an in-place pavement recycling project to rehabilitate a 3.66-mile section of pavement on I-81 near Staunton, Virginia. VDOT employed three in-place pavement recycling techniques, full-depth reclamation (FDR), cold in-place recycling (CIR), and cold central-plant recycling (CCPR). Materials for both the CIR and CCPR were produced using foamed asphalt with cement as an additive. A combination of cement and lime kiln dust was chosen for the FDR process.

 From the results of this study, the combined structural layer coefficient for the CCPR and FDR materials was calculated as 0.37. The structural layer coefficient for the CIR material was calculated as 0.39. The structural layer coefficient for the CCPR material was calculated to have a likely range of 0.37 to 0.44. Laboratory testing showed that the performance of the CCPR and CIR materials is expected to be similar. The field performance tests demonstrated that the section of pavement rehabilitated by the three in-place recycling methods continues to perform well after nearly 3 years of high-volume interstate traffic.

This report summarizes the findings from the second round of testing during the 2015-2017 research cycle at the NCAT Test Track for VDOT's three CCPR test sections. The study found that the performance of the three CCPR sections continues to be excellent after 20 million ESALs of loading. This was evidenced by the following examples of functional performance: no observable cracking at the pavement surface, rut depths less than 0.3 inch, steady measurements of ride quality and steady or increasing modulus values.

Cape seal was the treatment of choice to extend the service life of a 32 lane mile section of SR-260. By utilizing this treatment over the alternative solution, the agency was able to save $3 million, freeing up funds to treat more miles. 

Georgia DOT micromilled 500,000 square yards of interstate highway pavement in a single weekend. This innovative approach added 3-5 years of life and delayed complete removal/replacement, saving taxpayers millions of dollars and miles of inconvenience. 

The report is a guideline for the use of base stabilization. On page 19 of the report the results of three bituminous stabilized FDR test sections on the I-94 MNRoad test road are summarized. The three test sections consisted of various depths of FDR stabilized with emulsified asphalt with 3 inches of HMA. Anticipated design life was 5 years or a predicted 3 million ESALs. In 2017, after 10 yeqars of service and the application of 6 million ESALs, all 3 test sections had outperformed their anticipated design life for both cracking and ride. 

Cook County needed to rebuild 2 miles of deteriorating roadway, representing 27,000 square yards of road surface in the city of Orland Park. The existing pozzolanic base was rigid and contributing to reflective cracking, which meant that a simple asphalt overlay would not provide the best long term outcome.

Scottsdale slows thermal cracking with Type III Micro Surfacing on arterial and local streets at a scale never seen before.

The Ontario Ministry of Transportation (MTO) has been using CIR with emulsified asphalt since 1990. In 2003 they placed their first trial section of CIR using foamed or expanded asphalt (CIREAM) on Highway 7 east of Perth. A 5 km trial section of CIR with foamed asphalt was constructed adjacent to a 7 km section of CIR with emulsified asphalt. The test sections were monitored for performance over the next 10 years using the MTO's Automated Road Analyzer. The results indicated that both treatments are providing excellent long term performance and have been shown to significantly reduce or eliminate reflective cracking.

A robust preservation program goes a long way.  More than 2,500 lane miles were treated over 6 years to extend the life of Boise’s urban and residential roads using chip seal and preservation. 

Choosing Cold In-Place Recycling (CIR) using foamed asphalt saved time and money.

The biggest advantage using this process was the shortened construction time and keeping the road open to traffic.

Cold In-Place Recycling allowed Bobby Phillips, Roadway Superintendent for Jefferson County, Indiana, to restore Jackson Road, an ailing pavement in the Southeast corner of the state. This technology, new to Phillips and this region of Indiana, allowed him to also look to the future portion of the roadway’s life cycle. This was an opportunity to utilize innovative technology while also looking to the future for the pavement and the entire county as a whole network.

This trackless bond coat was shot for ALDOT on SR-102 in Walker County. Full proper coverage of bond coat and quick return to paving are features for this treatment.

Victoria, Australia utilizes pavement preservation techniques for higher quality roads, supporting heavy traffic, with a lower project cost. 

Like many of our nation's rural highways, Logan County Highway 25 was not only showing signs distress accumulated over its 40-year life, it was a safety concern for the traveling public with its narrow driving lanes.  Restricted by available funding to construct to federal standards with traditional rehabilitation options, the Logan County Highway Department utilized Full Depth Reclamation (FDR) to widen the pavement to the desired width and used a cape seal treatment as a surface course to safely carry traffic until additional funding becomes available.

Like many of our nation's rural highways, Logan County Highway 25 was not only showing signs distress accumulated over its 40-year life, it was a safety concern for the traveling public with its narrow driving lanes.  Restricted by available funding to construct to federal standards with traditional rehabilitation options, the Logan County Highway Department utilized Full Depth Reclamation (FDR) to widen the pavement to the desired width and used a cape seal treatment as a surface course to safely carry traffic until additional funding becomes available.

In 2005, Mississippi DOT preserved one of their most heavily trafficked highways, adding 14+ years of life while addressing friction, cracking and rutting-- Today in 2020, the highway has required no further treatments.

Crews work day and night to save Utah’s S.R. 9, implementing Utah’s first application of scrub seal in over 30 years and saving UDOT $80,000 per mile.

The City of Claremore set out to replace existing pavement on the Claremore Regional Airport runway through a full depth reclamation (FDR) treatment in which nine inches of the pavement were milled, mixed with an engineered emulsion, replaced and then compacted. 

Using CIR, SCDOT increases treated pavement area by 700% without increasing cost. 

An evaulation of Texas roads provided surprising results when the best friction numbers came from a 10-year-old microsurfacing project. So when TxDOt had a new project that involved maximizing friction on a high traffic road (1-10 in Crockett County) they chose microsurfacing because it can yield greater long-term friction results throughout its service than an ultra thin lift overlay, and at a lower cost.

Using Environmentally Sustainable Hot in Place Repaving on Baseline Road, MCDOT was able to save money, Improve Ride and safety by adding a safety edge and reducing carbon emmissions in a single pass, including use of tire rubber.

This is the final report for NCHRP 9-62 project where the authors developed a short pin raveling test to determine when a CIR pavement has sufficiently cured to allow opening to traffic and a long pin test to determine when the pavement has cured sufficiently to place the wearing surface. The authors have recommended additional field verification of the proposed test methods and threshold values. 

Cold In-Place Recycling allowed INDOT to repair a major 4-lane divided highway in Northern Indiana. US 30 showed large cracks that, upon further investigation, extended deep into the pavement structure.

The objectives of this Texas DOT funded study were to provide an update to the current TXDOT mixture design specification based on comprehensive laboratory testing and develop and calibrate a new generation fatigue performance model that accounts for strength and shrinkage cracking potential of cement treated aggregate base and subgrade soils.

The objectives of this Texas DOT funded study were to provide an update to the current TXDOT mixture design specification based on comprehensive laboratory testing and develop and calibrate a new generation fatigue performance model that accounts for strength and shrinkage cracking potential of cement treated aggregate base and subgrade soils.

Rankin has always utilized chip seals.  Three years ago, Rankin County began using micro surfacing.  They now have a pavement preservation toolbox utilizing micro surfacing, scrub seals, fog seals and cape seals. They have also adopted pavement management planning to determine the best times to utilize these treatments on certain roads.  With this wide range of preservation tools, Rankin County has been able to treat 100 miles and save the taxpayers $7.3 million.

This is the final report for NCHRP 9-62 where the authors developed a short pin raveling test to determine when a bituminous stabilized FDR pavement has suffeciently cured to allow opening to traffic and a long pin test to determine when the pavement has cured sufficiently to place the wearing surface.

Microsurfacing was successful in reducing wet weather crashes on bridge decks and approaches.  The benefits are due to micro surfacing's high friction characteristics.

Historic Lexington, Massachusetts is leading the charge once again with a comprehensive program that improves the town’s network and saves tax dollars.

MnDOT sets new standards using 3D milling and cloud monitoring of milling depths

Between 2015 and 2019, the City of Scottsdale has implemented one of the most aggressive and innovative pavement preservation projects in the United States whereas they placed approximately 10 Million square yards of micro surfacing.  Much of these areas received a double application of Type III micro surfacing followed by Type II micro surfacing.  Much of the material placed included the use of fiber reinforcement.  Originally awarded in early 2015, this massive Job Order Contract was renewed for four subsequent years resulting in significant benefit to the City’s entire road network by increasing the network’s average PCI from 70 to 83. 

The project was designed to address the pavement needs of entire neighborhood areas (Project PID numbers) in the residential areas.  Other specific areas included busy thoroughfares and massive parking lots.  Some locations required a double application depending on the distresses identified.  All work was performed per the City of Scottsdale’s project specifications and local MAG specifications.  All materials placed were required to have a project specific mix design, and all micro surfacing equipment was calibrated in the presence of City representatives. 

RoadResource.org played a critical role in maintaining one of Michigan’s County Chip Seal programs, when it was threatened due to personnel turnover. The county was considering reducing the program from 20-40 miles per year to 3-8 miles per year. 

As with most road networks, gaining ground with limited budgets is an iterative process. Experts maintain one of the single most important tenets of a preservation program is consistency. 

After a funding package opens new opportunities for the area, the Kent County Road Commission commits to using the resources to their fullest potential. 

Using a "triage" method, Delaware, OH is able to repair their network on a severely limited budget. 

The Alabama county’s comprehensive pavement preservation program dramatically improves road quality throughout the network. Learn what 17 years of improvements can do for a small network, with a small budget. 

In 2020 Utah Department of Transportation (UDOT) Region 4, with headquarters in Richfield, Utah, identified a 7.75 mile section of US 89 north of Fairview, Utah as a viable cost effective candidate for Cold in Place Recycling (CIR). Hales Sand & Gravel was awarded the job in 2021 and contracted with Coughlin Company to perform the CIR portion of the project.

Lewis County improved their average network condition by an estimated 40% over 3 years by revamping their approach to network management and budget allocation. By flipping the old mindsets on their head implementing a preservation-first plan, today the network looks completely different than before.

Using predictive modeling has helped elected officials and taxpayers understand their agency's proactive approach and compare the benefits of an Optimized vs a Worst-First Strategy.

What if you could show leaders the impact of current funding scenarios vs increased funding scenarios on network condition?

Austin Potts, Polk County's Pavement Manager, did just that. Using predictive modeling has helped elected officials and taxpayers understand their agency's proactive approach and compare the benefits of an Optimized vs a Worst-First Strategy.

The County of Fresno performed their first ever Cold Central Plant Recycling (CCPR) project. The project was a 2 lane, 14.5-mile segment of Lincoln Avenue, from SR 145 to Fig Avenue, with heavy agricultural traffic.

Dundee High School was able to realize cost and environmental savings using FDR to reconstruct their parking lots. Using FDR also resulted in time savings and an increased structural section.

Butler County, Iowa had previously used cold in-place recycling (CIR) followed by 3 inches of Hot Mix Asphalt (HMA) to maintain their county road system. Hot in-place recycling (HIR) was chosen to repair current distress rather than CIR as there were concerns about excessive pavement thickness and the distress was limited to the HMA layer.

FDR with cement was used to reconstruct subdivision roads that were built without an aggregate base. The cost savings compared to full reconstruction of these roads allowed the majority of the subdivision roads constructed with aggregate base to be resurfaced.