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HomeMy WebLinkAbout02/21/2011Council Work Session February 21, 2011 4:15 p.m. Council Chambers Roll Ca11. Approval of Agenda, as proposed or amended. 1. Presentation by Asphalt Paving Association of Iowa —Submitted by Bill Rosener, Executive Vice President. ADJOURNMENT Suzy Schares City Clerk CITY OF WATERLOO REQUEST FOR COUNCIL WORK SESSION Committee Communication Committee Meeting: February 21, 2011 Prepared: January 27, 2011 Dept. Head Signature: Eric Thorson, PE, Citv Engineer # of Attachments: 0 SUBJECT: PRESENTATION BY ASPHALT PAVING ASSOCIATION OF IOWA Submitted by: Person Presenting: Bill Rosener, Executive VP, Asphalt Paving Assoc. of IA Recommended City Council Action: One half hour work session with Power Point presentation and time for questions. Summary Statement Presentation on benefits of asphalt paving. Expenditure Required none Source of Funds N/A Policy Issue N/A Alternative N/A Background Information: CITY OF WATERLOO ASPHALT PAVEMENTS YEAR STREET 1992 High St. from Lime St. to Vine St. Pinehurst Lane from West Fourth St. to Cul-de-Sac Sears St. from San Marnan Dr. to Enterprise Ave. 1993 Mulberry St. from E. Sixth St. to E. Eleventh St. Saratoga Dr. from Alpine Dr. to Ridgeway Ave. South St. from W. Sixth St. to W. Ninth St. 1994 Cherry St. from Independence Ave. to Glenwood Ave. Fletcher Ave. from Campbell Ave. to Sergeant Rd. South St. from W. First St. to W. Fourth St. 1995 Byron Ave. from Minnesota St. to Ohio St. Parker St. from Logan Ave. to E. Fourth St. W. Third St. from Kimball Ave. to Washington St. 1996 Locust St. from W. Second St. to W. Third St. Park Lane from Fairlane to W. Ninth St. Sycamore St. from E. Eleventh St. east to the Tracks 1997 Mulberry St. from E. Eleventh St. to Vinton St. Olympic Dr. from Colby Rd. to Pheasant Lane South St. from W. Ninth St. to Eleventh St. 1998 Clay St. from Walnut St. to Almond St. Ingersoll Rd. from Aspen Dr. to Edgewood Dr. Meadow Lane from West Ridge Dr. to Ansborough Ave. 1999 Hawthorne Ave. from Hammond Ave. to W. Eleventh St. Rath St. from Vinton St. to Dunham Place Sheerer Ave. from Flower St. to University Ave. Perpetual Pavements The Asphalt Advantage Choosing the right paving material doesn't have to be a diffi- cult decision. If your goals include durability, cost-effectiveness and safety, you can't beat the Perpetual Pavement — Hot Mix Asphalt (HMA). Hot Mix Asphalt delivers the strength and qual- ity you demand at a cost that offers superior value. From initial construction throughout its long life, asphalt delivers. What is Hot Mix Asphalt What is Perpetual Pavement Hot Mix Asphalt is a combination of 95% stone, sand or gravel bound together with asphalt cement, a product of crude oil. The asphalt cement is heated and mixed with the aggregate, then transported to the paving site where it is placed with an asphalt paver in layers. The asphalt cement is the key to the asphalt advantage, giving Hot Mix Asphalt a flexible quality, a distinct advantage over Portland Concrete in resisting the pressures of the freeze and thaw cycle of Iowa winters. A new approach to HMA construction called Perpetual Pavement significantly prolongs the life of the pavement as well as cuts down on the time and cost of construction. Hot Mix Asphalt is placed in layers creating a perpetual pave- ment. The base layer is designed to be more flexible to absorb and diffuse the stress of heavy traffic as well as preventing thermal cracking due to the freeze and thaw cycle. On pavements designed for heavier use, a strong, load -bearing intermediate layer is placed. Finally, the top layer is designed to resist the pressures of traffic and pro- vide a smooth, rut -resistant surface. Together, the layers produce a pavement that can withstand the toughest pun- ishment and weather fluctuations. When the time comes for pavement rehabilitation, the surface layer can be overlaid or milled off for recycling while leaving the remaining base layers intact — a distinct cost advantage over other pavement materials. Surface layer can be repaired quickly, easily, and at a lower cost • Keeps motorists happy with a consistently smooth, safe and quiet driving surface • It's 100% recyclable, saving money and valuable resources The Hard Facts about Equivalence When it comes to strength, asphalt stands up to the toughest challenges. Although Hot Mix Asphalt and concrete are not equal on an inch -to -inch basis, the difference is less than you might think. Portland Concrete must be placed at minimum depths often unnecessary for light traffic or parking lot projects. Where traffic situations require more strength, these examples illustrate how to compare concrete to Hot Mix Asphalt. AASHTO Strength Coefficient Values per 1" of Pavement Portland Cement Concrete Type A Asphalt Type B Asphalt Crushed Stone Base .50 .44 .40 .14 Full Depth Asphalt 2.0" Type A Asphalt @ .44 = .88 5.5" Type B Asphalt @ .40 = 2.20 Total: 7.5" Hot Mix Asphalt = 3.08 (Asphalt w/6" Rock Base 2" Type A Asphalt c .44 = .88 3" Type B Asphalt @ .40 = 1.20 6" crushed stone base (0).14 = .84 Total: 5" Asphalt w/ 6" rock base = 2.92 A Hot Mix Asphalt delivers quality, strength and durability! Key Advantages of Hot Mix Asphalt Cost effective — Asphalt not only has lower initial costs, it's more cost effective in the long run. Because asphalt can be built quickly, is durable, safe, easy to maintain, and 100% recyclable — on every level, asphalt is more cost effective than any other material for the entire life cycle of the pavement. Quick construction — Asphalt pavements can be placed much more quickly than other products because it requires virtually no curing time. This significantly reduces safety risks for both construction workers and motorists as con- struction zones are in place for shorter periods. It also means fewer traffic delays and fewer repercussions for businesses. Staged construction — For your paving project, Hot Mix Asphalt allows you to place the hard base layer, complete your building project, then place your surface layer upon completion. Completing the paving in stages provides a cleaner, easier work site and allows you to budget for the cost in stages as well. Durable, long lasting — When constructed with the appro- priate strength (see equivalence examples at left) asphalt will actually last as long or longer than concrete. Its flexible qualities contribute to its strength and resistance to cracking. Safe and skid -resistant — The smooth surface asphalt provides maximizes tire contact with the road, increasing skid -resistance. It's safer in bad weather as well, heating more quickly to melt snow and ice. Smooth and quiet — One of the major advantages of HMA for motorists is a smoother, quieter ride. Its smooth surface also results in greater fuel efficiency, less wear and tear on vehicles, and longer pavement life. 100% recyclable — Recycling asphalt saves U.S. taxpay- ers over $300 million each year — not to mention the savings to our environment. When in need of repair, asphalt can be milled and resurfaced using recycled materials. In fact, it is the most recycled material in America. Asphalt is a renewable surface made from renewable resources. Superior Value, Best Choice The advantages of today's Hot Mix Asphalt simply add up to a superior value. Asphalt performs in terms of strength and longevity. When you evaluate its economical process, unique safety advantages, smooth, skid -resistant nature and environment -friendly recycling qualities, Hot Mix Asphalt meets all of your needs. Your local Asphalt Paving Association of Iowa (APAI) contractor will work with you as strategic partners in developing the most effective plan for your paving needs and long-term goals. Call the contractor listed below or the APAI for more information. For more information Asphalt Paving Association of Iowa 3408 Woodland Ave. #209 West Des Moines, Iowa 515-222-0015 www.apai.net THE ECONOMIC VALUES OF PAVEMENT OVERLAY ALTERNATIVES The majority of the US highway roadway system has been completed for many years, thus requiring agency resources to be focused on maintaining and rehabilitating existing pavements. Economic analysis of pavements must consider initial costs, design life, maintenance costs over the life of the pavement and salvage value at the end of its life -cycle. This case study examines five pavement rehabilitation methods for asphalt roadways using equivalent 20-year pavement overlay designs in contrast to the 40-year life cycle designs traditionally used for new construction and full -depth reconstruction. These designs will be judged under the scrutiny of the economic value of the pavement from the beginning to the end of the 20-year pavement life -cycle. R. Christopher Williams, Ph.D. and Larry Mattusch, P. E Over ay A ternatives Cost Per Lane Mi e tti $20,000 5 w Z J $15,000 oc w a g2 $10,000 a J J ad o $5,000 ESALs 300,000 1,000,000 3,0009000 HMA Overlay AMA ()verb $6161 $6,950 79739 DeAogn ► SALs 300,000 1,000,0 3,00C,O Mill & HMA Overlay CI PR & HMA Overlay OVERLAY ALTERNATIVES oil & HMA nrflay 7,9C8 99229 T 0,551 ,Yn 09729 Interlay & PCC Overlay Mall PCC Zwevfiay $13,43 $1z,472 SIL O5U Interlayer & PCC Overlay $20,974 $22,015 S229394 Findings Rehabilitation of hot mix asphalt pavements is one of the domi- nant pavement construction practices and will continue as high- way facilities mature. The current socio-economic environment is demanding use of public monies to be more efficient with sound environmental practices. The use of life -cycle cost analysis is considered the best method for evaluating competing pavement rehabilitation methods. The ranking of the best economic value for the methods studied were: 1. HMA Overlay, 2. Mill with an HMA Overlay, 3. Cold In -Place Recycling with an HMA Overlay, 4. Mill with a PCC Overlay, and 5. An HMA Interlayer with a PCC Overlay. The current FHWA method of conducting life -cycle cost analysis through end of life value (salvage value) does consider the social and environmental stewardship associated with recycling materials; in addition, this study leads to the conclusion that the best method for rehabilitating HMA pavements is by using HMA materials to rehabilitate these roadways. Burnham, Thomas, "Forensic Investigation Report for Mn/ROAD Ultrathin Whitetopping Test Cells 93, 94, and 95", Report Number MN/RC 2005-45, Maplewood, Minnesota, 2005. Romanoschi, Stefan A.; Dumitru, Cristian; Lewis, Paul; and Hossain, Mustaque, "Accelerated Testing for Studying Pavement Design and Performance (2004): Thin Bonded Rigid Overlay and PCCP and HMA (CISL Experiment No. 13)", Report Number FHWA-KS-08-8, 2009. Snyder, Mark, "Lessons Learned from MnROAD (1992-2007) Whitetopping Design, Construction, Performance, and Rehabilitation" 88th Annual Meeting of the Transportation Research Board Paper #09-1737, Washington, DC, 2009. Thompson, Marshall R.; Garcia, Luis; and Carpenter, Samuel H., `Cold -In -Place Recycling and Full -Depth Recycling with Asphalt", Report # FHWA-ICT-09-036, 2009 Von Quintus, Harold; Simpson, Amy; and Elthan, Ahmed; "Rehabilitation of Asphalt Concrete Pavements: Initial Evaluation of the SPS-S Experiment -Final Report', Report # FHWA-RD-01-168, 2001. Walls, James III and Michael Smith, "Life -Cycle Cost Analysis in Pavement Design- Interim Technical Bulletin", Federal Highway Administration, Washington, DC, 1998. Pavement Designs For each of the pavement rehabilitation strategies, three traffick- ing levels were examined: 300K, 1.0, and 3.0 million equivalent single axle Toads (ESALs) over a 20-year design period at an 80% level of reliability, resulting in the determination of fifteen pavement designs using the 1993 AASHTO Pavement Design for New and Rehabilitated Pavements. The 20-year pavement designs are summarized in Table 1. Table 1. Summary of Pavement Designs Using 80% Level of Reliability Design Strategy HMA Overlay Milling with HMA Overlay Cold In -Place Recycling with HMA Overlay Milling with PCC Overlay (Bonded Overlay) HMA Interlayer with PCC Overlay (Bonded Overlay) 300K 1M 3M 300K 1M 3M 300K 1M 3M 300K 1M 3M 300K 1M 3M MQDDong Depth 0.0" 0.0" 0.0" 2.0" 2.0" 2.0" 4.0" 4.0" 4.0" 0.5" 0.5" 0.5" 0.0" 0.0" 0.0" Cv; id0ay iihilckness 2.0" HMA 3.5" HMA 5.0" HMA 3.5" HMA 5.0" HMA 6.5" HMA 4.0" CIPR + 2.0" HMA 4.0" CIPR + 3.5" HMA 4.0" CIPR + 4.5" HMA 5.0" PCC 6.0" PCC 6.5" PCC 1.0" HMA + 5.0" PCC 1.0" HMA + 6.0" PCC 1.0" HMA + 6.5" PCC 1 The properties of the materials used in the designs are as follows: ■ Existing soil with stabilization resulting in a resilient modulus value of 3500psi, ■ 6-inches of crushed stone with a layer coefficient of 0.14/inch, ■ Existing HMA with a layer coefficient of 0.30/inch, ■ HMA Overlay with a layer coefficient of 0.45/inch, ■ Cold in -place recycled pavement with a layer coefficient of 0.36/inch, and ■ PCC overlay with a k-value of 236. economic Analysis of Designs The economic analysis was done following the Federal Highway Administration's (FHWA) recommendations as reported in Life -Cycle Cost Analysis in Pavement Design (walls and Smith, 1998). The FHWA recommends using the equivalent uniform annual cost analysis approach which considers the effects of the time/value of investment through the use of a discount rate, initial costs, maintenance costs, salvage value, and design life. This method was utilized in examining the aforementioned pavement rehabilitation methods to determine yearly annual costs for each design at an 80% level of reliability. The economic parameters used in the life cycle cost analysis are Iowa Department of Transportation letting values from September 2007 through September 2009 and are summa- rized in Table 2 The outcomes of the life cycle cost analysis are summarized in Figure 2 and Table 3 below. ThbUe 2. Values used in Lois Cycle Cost Analysis' ra eter Cos sNalues Discount Rate 3.0% Survey Staking' HMA Milling $5,000 at start of construction $1.90 per square yard Cold In -place Recycling $3.50 per square yard, Pavement (with emulsion) 4.0" depth HMA Overlay (using $464/ton liquid asphalt) $55.32 per ton 1" HMA Interlayer 5" PCC Overlay $5.20/ per square yard $15.60 per square yard 6" PCC Overlay $17.80 per square yard 6.5" PCC Overlay $18.60 per square yard Maintenance of HMA Pavement2 $3,800 per year Maintenance of PCC Pavement2 $1,900 per year PCC Demolition $5.40 per square yard HMA Salvage Value' $1.25 per square yard, per inch of HMA depth 1 Values are IDOT Bid Tab Values from September 2007 through September 2009. 2 Values assigned due to high value variability within IDOT bid tabs or no value available. 3 Includes the HMA salvage value as well as the associated costs of milling and trucking. Background The most common rehabilitation strategy for existing HMA pavements is using an HMA overlay, both with and without milling the existing HMA roadway. The Long Term Pavement Performance Program estab- lished the Specific Pavement Studies 5 (SPS-5) experiment consisting of 210 pavement test sections to examine rehabilitation strategies of asphalt concrete pavements (Von Quintus et al., 2006). The SPS-5 experiment considers different rehabilitation techniques and site con- ditions that were primarily constructed in 1989 and 1990. The study found less transverse cracking on sections with intensive surface preparation than on sections with minimal surface preparation prior to the overlay and that the International Roughness Index values were lower for overlays placed on fair condition and milled pavements. Recent research conducted by Thompson et al. (2009) found both Cold -in -place Recycling (CIPR) and full -depth reclamation of pave- ments to be successful in Illinois. CIPR has been used in Iowa suc- cessfully for many decades on lower volume roads and generally consists of cold in -place recycling all but 2-inches of the existing HMA and placing a 2 to 5-inch HMA overlay (Chen et al., 2009). Recent full-scale testing done in Kansas (Romanoschi et al, 2009) and Minnesota (Burnham, 2005) on concrete overlays have found the use of 6-inch concrete overlays to be superior to those of 4 and 5-inch in thickness. Regardless of the concrete overlay thickness, both researchers found that the bond between the concrete and asphalt pavement surfaces is critical to the performance of the overlays (Burnham, 2005 and Romanoschi et al, 2009). Successful bonding strategies included milling the existing asphalt surface or the use of an HMA interlayer. Further, the use of fibers and a reduced panel size (3ft by 3ft as compared to 4ft by 4ft) improved performance and plac- ing the joints further from the trafficked wheel paths (Snyder, 2009). Socio-Economic Value of Recycled Pavements The American public has determined that preservation of natural resources is both environmentally and fiscally responsible. HMA pave- ments are commonly recycled through the use of milling machines with the recycled asphalt pavement (RAP) being reused in the new HMA mixes. Additionally, the use of cold -in -place recycling may be used by first injecting the milled asphalt pavement with a rejuvenating emulsion and then laying the recycled material on the grade as an intermediate stress relief layer. In both cases, the existing asphalt cement and aggregates are recycled and the economic value is recouped when the pavement is rehabilitated. PCC pavements may be crushed and reused as an aggregate base but the value of the portland cement is not recovered through this method and the removal and crushing operation costs are prohibitive. Design Considerations HMA pavements are the predominant pave- ment in the United States. These pavements generally consist of a hot -mix asphalt (HMA) surface course, an intermediate and/or HMA base course, a compacted stone base and a stabilized dirt subgrade. In rehabilitating this typical pavement structure, this study looks at the five most common and economical methods for rehabilitating a typical HMA pavement structure: 1. HMA overlay, 2. Milling of the existing HMA with an HMA overlay, 3. Cold -in -Place Recycling with an HMA overlay, 4. Milling of the existing HMA with a Portland Cement Concrete (PCC) overlay, and 5. A one -inch HMA interlayer with a PCC overlay. A baseline pavement structure for this study consisted of six inches of HMA on six inches of rock base, on a compacted dirt subgrade. The five rehabilitated pavement structures are represented below in Figure 1. HMA Overlay 6.0" Existing HMA 6.0" Crushed Stone Compacted Subgrade (1) HMA Overlay • HMA Overlay 4.0" Existing HMA 6.0" Crushed Stone Compacted Subgrade (2) HMA Mill & HMA Overlay HMA Overlay 2.0" xisting YA 6.0" Crushed Stone Compacted Subgrade (3) Cold In -Place & HMA Overlay PCC Overlay 5.5" Milled Existing HMA 6.0" Crushed Stone Com .acted Subgrade (4) HMA Milling with PCC Overlay • PCC Overlay 6.0" Existing HMA 6.0" Crushed Stone Compacted Subgrade: (5) HMA Interlayer with PCC Overlay Figure 1. Pavement Design Overlay Options • • • Better ROAD Roads For The Government/Contractor Project Team SCIENCE by Bob Bushmeyer The Quest for Long -Life Asphalt Pavement Perpetual pavement is a marketing campaign, but it's an engineering concept, too. Here's what the buzz is about. Turnpike honored with first perpetual pavement award he New Jersey Turnpike Authority was honored with the first -ever Perpetual Pavement Award p a d last September. The turnpike's asphalt pavement was honored by the Asphalt Pavement Alliance for a half - century of service. "Even though 50 years of heavy use have punished that pavement, motorists on the New Jersey Turnpike are still traveling on the original pavement structure," says Mike Kolos, APA chairman, "only surface treat- ments have been used to maintain the pavement." Construction of the turnpike began in January 1950 and was completed in 23 months. Fifty years later, and 148 miles long, the New Jersey Turnpike is one of the most heavily traveled roadways in the nation. To celebrate this anniversary, the New Jersey Historical Society opened a new exhibition on the turnpike entitled What Exit? "The New Jersey Asphalt Pavement Association con- gratulates the New Jersey Turnpike Authority for 50 years of outstanding service as New Jersey's premier super- highway," says John Post, president of the association. "It is entirely fitting that the APA's first ever Perpetual Pavement Award recognizes the fact that not one mile of this durable road has ever had to be recon- structed. Our members helped build and maintain the Turnpike. We are a part of its history and its future." sphalt pavers have see e VI re, and- ° - inc u° es perpetual pavemento For years, the conventional wisdom has been that asphalt roads have a lower ini- tial cost, a shorter effective life, and a high- er life -cycle cost than concrete roads. For that reason, even though asphalt is speci- fied for most roads and for a huge portion of road surfaces in North America, portland cement concrete is often specified for new road construction or complete reconstruc- tion involving long-term lane closures. To combat the notion that asphalt roads are short-lived and expand the market for hot -mix asphalt technology the asphalt industry has created long -life asphalt pavement designs and is mount- ing a campaign to make road engineers and managers aware of them. From Virginia to Michigan to California, and across the oceans, the particulars of perpetual pavement design are being rec- ognized and applied. WPl at fis a perpetha pavement? Long-lived asphalt pavements aren't new, proponents say. What is new is the perpetual pavement design, which takes Reprinted with permission from BETTER ROADS February 2002 © James information Media, Inc. All rights reserved. 226926 began in 1995 and continues into the 21st century. A life -cycle cost analysis performed early in the design phase by consulting firm Resource International showed that hot -mix asphalt was the most economical pavement type for the huge widen- ing project, reports The Asphalt Institute. Since the original concrete pavement in the 160- mile section had been overlaid with asphalt, turnpike officials wanted the same surface on the third lane. But the question was whether to use asphalt or con- crete in the 10 inches of base underneath. The com- mission ultimately decided to use a hot -mix asphalt base for the entire roadway except for 15 miles where PCC was used due to very low subgrade strength. The structure of the new third lane begins with 6 inches of 2-inch (maximum size) crushed aggregate base placed on compacted subgrade. Placed on top of that is 10 inches of large stone (2-inch maximum size) asphalt base course, followed by a nominal 3.75-inch (variable thickness) intermediate course. Completing the pavement structure is a 1.25-inch surface course with crushed slag aggregate added for skid resistance. On to Do \iv rUnder Asphalt pavements incorporating some perpetual pavement principles are outperforming expectations in Sydney, Australia, according to the Asphalt Pavement Association of Australia. One example is Southern Cross Drive, on Sydney's Orbital Route, which provides the main access to Sydney Airport and its southern suburbs. This full -depth asphalt pavement was constructed in 1969. "It's a pavement which was virtually maintenance - free for 25 years, before deterioration became apparent and rehabilitation was required," the AAPA says. One profile is of full -depth asphalt on a sand- stone/sand subgrade, and the other profile is of a deep -strength pavement type. The asphalt through- out the depth of each pavement profile is of a very stiff mix to reduce strain in the subgrade. "Australia and the USA are experiencing the same sort of advantages from well designed and construct- ed deep strength and full depth pavements on major roads," the AAPA says. "The indications are that these sorts of pavements can perform beyond widely held expectations concern- ing their life and maintenance needs," the AAPA says. "The adoption of appropriate design concepts for full depth AC heavily trafficked pavements help immea- surably, as do the other key ingredients for success: good design and construction implementation." Vircciiffla evaf is es specs Last year, the Virginia Transportation Research Council was evaluating hot -mix asphalt density specs in its project, Evaluation of Techniques to Measure Asphalt Pavement Density and Permeability. The project evaluated lab and field permeability devices for their potential to improve VDOT's current density specification or to be used in a replacement specification. It also evaluated the state's hot -mix asphalt pavement density specification, and sought to develop a statistically sound quality assurance pro- gram for density testing that required a minimum amount of VDOT staff time. "Based on preliminary testing that indicates severely inadequate density levels, the service life of Virginia's pavements could be improved by 50% or more," VTRC reports, regarding the benefits of denser pavements. "Developing specifications that provide impermeable asphalt pavement surfaces will help protect base asphalt from moisture damage and act as a step toward perpetual pavements." And in the Badger State, the Wisconsin Asphalt Pavement Association reports that a perpetual pave- ment project was built in 2000 on Wisconsin S.R. 50 near Lake Geneva, and a project was designed in 2001 for a weigh station off ramp on 1-94 in Kenosha County. The latter project involved an 11-inch asphalt structure designed from the bottom up to include lay- ers that are fatigue- and rut -resistant, and topped with a skin layer of high-performance mix that can more easily and quickly be rehabilitated when needed. Vigorous new riniarikeiling Perpetual pavement designs are being popularized in the United States by the new promotion arm of the asphalt paving industry, the Asphalt Paving Alliance. Launched in 2000, APA is an industry coalition composed of the Asphalt Institute, National Asphalt Pavement Association, and the State Asphalt Pavement Associations, an umbrella group represent- ing local associations in 36 states. APA's activities include publications, outreach through industry meetings and conferences, and targeted communica- tions to public officials and the general public. BR c verYa f 4.7% asphalt by weight of aggregate 4.7% asphalt by weight of aggregate E rea 1 in. (25 mm) OGFC (asphalt rubber binder) 3 in. (75 mm) PBA-6a mix 5 in. (125 mm) AR-8000 mix with fabric interlayer Broken and seated PCC Subgrade Perpetual pavement principles are being used in Caltrans' 1-710 project in Long Beach. The cross-section shown above depicts a three -lift, 9-inch overlay that will top cracked -and -seated portland cement concrete pavement. an already successful design to another level. Today's perpetual pavement design is a three -layer hot -mix asphalt pavement that is intended to provide pavement life spans of 50 years or more, with occa- sional asphalt overlays to maintain optimum rideabil- ity. The layers are constructed of different asphalt designs. They are topped with a sacrificial friction course intended to be cold -milled and overlaid with asphalt at 15-20 year intervals to restore drivability. In practice, the actual composition and depth of the sections will vary according to anticipated conditions and traffic loads, including the percent of truck traffic. As envisioned, a perpetual pavement starts with a lower layer specifically designed to resist bottom -up fatigue cracking. The middle layer uses an asphalt A smooth asphalt surface needs sound underlying engineering for a Tong -life road. E LC) N co c r >> ' \ [(0 o 4.7% asphalt by weight of aggregate 4.7% asphalt by weight of aggregate 5.2% asphalt by weight of aggregate 1 in. (25 mm) OGFC (asphalt rubber binder) 3 in. (75 mm) PBA-6a mix 6 in. (150 mm) AR-8000 mix 3 in. (75 mm) AR-8000 mix, RB (rich bottom) mix Subgrade Overlay sections cannot be used under 1-710 overpasses due to clearance problems, so Caltrans is removing the old pavement and installing a 4-layer, 13-inch, full -depth asphalt replacement section (above). mix designed to support anticipated traffic loads. This design of massive, flexible bottom layers pre- vents pavement distress which develops in the bottom layers Distress is now confined to the surface course, where it is more easily repaired. This surface layer may be of any current HMA design, be it Superpave, stone matrix asphalt, or modified asphalt open -graded friction course. The combined thickness of all the lay- ers prevents rutting in the base or subgrade. "The design starts with a strong HMA base layer, flexible enough to prevent bottom -up, structural fatigue cracks," says Gerald Waelti, executive direc- tor, Wisconsin Asphalt Pavement Association. "As a long-lasting and smoother paving material, perpetual pavements using HMA could spell dramat- ic savings for state and federal transportation agen- cies striving to balance tight road budgets," Waelti says. "And because asphalt pavements are 100% recy- clable, perpetual pavements offer further cost advan- tages as well as environmental benefits." Jnd rLyffi,g ero rie r rng r cuplesI There is little doubt among promoters that perpet- ual pavements will perform with reliability because they are based on sound engineering principles. These principles are articulated in a concept paper titled Perpetual Pavements, by Jim Huddleston, P.E., Asphalt Pavement Association of Oregon; Mark Buncher, Ph.D., P. W L, The Asphalt Institute; and David Newcomb, Ph.D , P.E., National Asphalt Pavement Association. ROAD SCIENCE Asphalt pavements incorporating some perpetual pavement principles are outperforming expectations in Sydney, Australia. Cold milling of top layer of aged, worn hot -mix asphalt — followed by replacement with fresh driving course — is integral to perpetual pavement concept. which uses perpetual pavement principles. This full -depth section 500 feet on either side of an overpass will consist of a 3-inch rich bottom layer, with 6 inches of a standard asphalt mix, and a 3-inch modified asphalt pavement surface course, topped with a 1-inch open -graded friction course for the wearing surface. Long and Monismith report that the full -depth asphalt concrete was designed using multi -layer elastic analysis. "The procedure requires determina- tion of the principal tensile strain on the underside of the asphalt concrete pavement in order to miti- gate bottom -up fatigue cracking," they write. "Determination of the vertical compressive strain at the sub -grade surface is also required to minimize the contribution of the layers below the asphalt con- crete to surface rutting," they say. "Fatigue resistance of mixes was determined using the SHRP-developed flexural fatigue test, which permits determination of the relationship between the applied tensile strain and the load repetitions to cracking." This full -depth structural section includes the use of a rich -bottom design for the lower portion of the full -depth HIM Binder content for this section is 0.5% higher than the design binder content, accord- ing to Long and Monismith. "Increasing the binder content facilitates greater compaction," they say, "which improves the fatigue resistance of the mix; and, because this layer is at the bottom of the asphalt concrete, the rutting resistance of the pave- ment is not compromised." This section under the overpasses will consist of an AR-8000 mix (for its higher stiffness), and a PBA-6a mix (for its greater rut resistance). Use of both mixes gave the thinnest pavement section while ensuring the fatigue and rutting performance, in keeping with perpetual pavement principles. For the I-710 driving or wearing (friction) course, an open -graded friction course with an asphalt rub- ber binder will be used. Because of its porous struc- ture, open -graded friction course will reduce tire splash, the potential for hydroplaning, and tire noise. C',rck=anld scat lli1u» open pa11`%lrlIJll'vUiil For the rest of the 1-710 pavement in Long Beach, the existing concrete pavement will be cracked and seated to create a sound base, then topped with asphalt overlays meeting perpetual pavement criteria. A 1-inch leveling course over the cracked -and - seated FCC base will be topped with a geotextile fabric. Another 4 inches of asphalt will be placed over the geotextile fabric, followed by a 3-inch modi- fied asphalt pavement surface course, and a 1-inch open -graded friction course for the wearing surface. A finite element analysis was performed to select the total thickness for the overlay section above the cracked -and -seated concrete, Long and Monismith say. The same materials as those used in the full - depth replacement sections under overpasses will be used there as well. fl ��continues �� � �����'�G����?� work In Ohio, the Ohio Turnpike Commission is widen- ing 160 miles of the 241-mile-long Ohio Turnpike the biggest and most complex asphalt rehabilitation project in Ohio's history using perpetual pave- ment principles, the Asphalt Institute reports. The multi -year project adds a third traffic lane in each direction to the most heavily traveled portion of the highway from Toledo to Youngstown. Work f A\-> r \\.` 1 The designs developed are based on accommodating 200-million equivalent single -axle loads for a design period of 30 years. temperature grading," they write. The mix design should be a standard Superpave mix, and the design asphalt content should be the optimum. Weaiing Surface or rfctgon Course. The design of the wearing surface depends on local requirements and economics. "In some cases the need for rutting resistance, durability, impermeability, and wear resistance may dictate the use of SYJA [stone matrix asphalt, a low -fines, stone -on -stone mix]," says Huddleston. "This may be especially true in urban areas with a high percentage of truck traffic." In instances where the overall traffic is not as high, or in cases where the truck traffic is lower, the use of a well -designed, dense -graded Superpave mix may be more appropriate, they say. a< COME_ `ecc hl u :4l orLfl a The first major perpetual pavement placement in the United States began last spring in Southern California. Initial work began in March 2001 on this S 10.7- million project, which will rehabilitate a 2.5-mile stretch of I-710 (Long Beach Freeway) between the Max. Tensile Strain 4„ Zone to of High 6 Compression Pavement Foundation High Quality HMA orOGFC 1.5-3" High Modulus Rut Resistant Material 4-7" Flexible Fatigue Resistant Material 3 - 4" Perpetual pavement concepts call for enough stiffness in the upper layers to preclude rutting, and enough total pavement thickness and flexibility in the lowest layer to avoid fatigue cracking from bottom of pavement structure. Adapted from a paper by Huddleston, Buncher, and Newcomb -Asphalt Pavement Alliance. Increased binder content aids compaction, improves fatigue resistance, and reduces rutting. Pacific Coast Highway and the San Diego Freeway in Long Beach. Initial preparation and structural work continued through 2001, with the actual paving to begin this year. "The project marks the first large-scale use of asphalt concrete, long -life pavement on a major California freeway," says a spokesman for the California Department of Transportation "The goal is to develop and demonstrate new techniques that can replace aging pavements throughout the state with minimum traffic delay and less inconvenience to motorists." The new pavement design is the result of partner- ing at every level of project interest. A coalition of refineries, aggregate and emulsion suppliers, pavers, and the California Asphalt Pavement Association worked with the University of California-Berkeley's Pavement Research Center and Caltrans as part of its Longer Life Pavement Rehabilitation Team to develop the performance specification. "The designs developed for the project are based on accommodating 200-million equivalent single -axle loads for a design period of 30 years, significantly more than the typical pavement design period," say researchers Fenella Long and C L. Monismith. Full -depth under overpasses To maintain vertical clearance under overpasses, workers will remove existing pavement and con- struct a full -depth section of asphalt pavement, PERPETUAL PAVEMENT Structured for the Future Just imagine it: Total pavement reconstruction, the remove -and -replace option, is rendered virtually obsolete. The only pavement rehabilitation needed would be surface replacement at about 20-year intervals. With Hot Mix Asphalt (HMA), we have the technology to achieve just that. We call it Perpetual Pavement. The concept is not a new one. In fact, full - depth and deep -strength asphalt pavement structures have been built since the 1960s. Today, recent efforts in materials selection, mixture design, performance testing, and pavement design offer a methodology to obtain performances exceeding 50 years from asphalt pavement structures, while periodically replacing the pavement surface and recycling the old pavement material. Perpetual Pavements have three distinct features: a rut -resistant and wear -resistant surface layer; a rut -resistant, durable intermediate layer; and a combination of adequate asphalt thickness and flexibility to resist deep fatigue cracking. "Perpetual Pavement is engineered so that any distress that occurs is confined to the upper pavement layer," explains David Newcomb, vice president for research and technology at the National Asphalt Pavement Association. "At some point in time, say, at about 20-plus years, you go back and mill out the surface and replace it with a new surface." Maintaining a Perpetual Pavement can be compared to maintaining a house or any other structure. The owner may choose to paint it, put a new roof on it, or add to it. With Perpetual Pavement, contractors can maintain and even enhance an aging pavement, rather than breaking it up and hauling it away to a landfill, because the original structure is still sound and has great value. In addition, the process is environmentally friendly because the pavement material that is milled off is 100 percent recyclable. Recent research has shown that the asphalt pavement industry is the nation's number one recycler. THE NEW ASPHALT, ABSOLUTELY! SMOOTH I DURABLE I SAFE I QUIET Traylor says what he's really excited about is the potential to use the Perpetual Pavement concept to rehabilitate old Portland Cement Concrete pavements. He says most of the Illinois DOT's money is being spent for reconstruction and rehabilitation, not for new pavements. "The Perpetual Pavement concept works not only for new construction, but it also eliminates the need for reconstruction, because you take the concrete pavement, rubblize it, and put the same full -depth asphalt concept on top of that," says Traylor. "You start with a rich bottom mix, select aggregate properties to prevent strip- ping, and top it off with an SMA. And we have a mechanistic design for rubblizing and overlay work." Putting a Perpetual Pavement over cracked -and -seated concrete is exactly what they're doing in southern California, where a Perpetual Pavement is being built on the Long Beach Freeway, Interstate 710, in 2001 and 2002. The existing con- crete pavement will be cracked and seated and then overlaid everywhere, except at overpasses. To maintain clearance under bridges, the concrete and base at those locations will be removed and replaced with full -depth asphalt. The full -depth sections under bridges on the 1-710 project will consist of a total thickness of 13 inches of HMA. The top layer will be an open -graded surface course over three inches of a rut -resistant mixture containing an engineered binder. The next -down HMA layer will be a 6-inch-thick dense -graded mix made with a relatively stiff binder. And the bottom fatigue layer will consist of a 3-inch binder -rich mixture. The cracked concrete will be overlaid with five inches of dense -graded mixture, followed by a 3-inch rut -resistant layer, and the overlaid PCC sections will have an open -graded surface mixture. • Although Perpetual Pavements are a concept mainly aimed at high -volume roadways, the justification may be made for medium- and low -volume roads as well. "The concept is one that is applicable at all levels of traffic," says Newcomb. "You have to be cognizant of what a reasonable thickness is in order to get a Perpetual Pavement out of it. It's pretty evident that the thickness has to be greater than eight inches for the asphalt portion of the section." Other advantages of Perpetual Pavement: They provide a consistently smooth and safe driving surface; Because they incorporate recycling techniques, they are environmentally friendly; The technology and knowledge to build them is proven. In summary, a Perpetual Pavement is designed to provide 50-plus years of life in the pavement structure with periodic surface renewal at about 20-year intervals. There is no recon- struction involved with a Perpetual Pavement. Asphalt Pavement Alliance Toll Free: 888.468.6499 E-mail: publ ications@asphaltal I iance.com www.AsphaltAl liance.com ASPHALT PAVEMENT ALLIANCE 1 The Asphalt Pavement Alliance is a coalition of the Asphalt Institute, the National Asphalt Pavement Association, and the State Asphalt Pavement Associations. The Asphalt Pavement Alliance's mission is to implement a unified, industry -wide plan that furthers the use and quality of asphalt pavements.The Alliance will accomplish this through engineering, research, technology transfer, educa- tion and innovation. AA-2 Copyrigh o 2001 Asphalt Pavement Alliance Building on a good foundation The design begins with a good foundation upon which to construct the thick asphalt layers. The asphalt is thick enough to resist bending so that cracks do not form at the bottom of the asphalt section. This layer can be made even more resistant to cracking either through the use of a little more asphalt cement in the mix, creating lower voids, or through the use of engineered binders in that layer, to preclude the cracks from starting. The intermediate layer of the structure has the quality of rut resistance. This layer can be designed to resist rutting, again through the use of high -quality aggregate and engineered binders. The top surface layer is a renewable surface that can be designed for specific applications. In some instances, the use of a conventional dense -graded Superpave mixture is adequate. In very high -traffic areas, the use of Stone Matrix Asphalt (SMA) may be attractive, provided that the materials are available to construct it. And in some places, engineers may want to use an Open Graded Friction Course (OGFC) on the surface, to reduce splash and spray and to provide better skid resistance during rainstorms. Both OGFC and SMA also have the advantage of absorbing road noise. Research supports the concept An excellent example of an existing Perpetual Pavement design procedure is the Transport Research Laboratory Report No. 250 by Nunn, Brown, Weston & Nicholls. (TRL is the leading transportation research institution in the U.K.) Nunn and his colleagues found that high rates of rutting were associated with thin asphalt pavements. Sections of more than 200 mm, or eight inches, tended to show a relatively slow rate of rutting. And in pavements thicker than eight inches, the rutting was con- fined to the top layer of the pavement. As a result, only surface work was required to correct the problem. In thicker asphalt pavements, Nunn and his colleagues found that cracking did not start at the bottom and work its way upward. Instead, it occurred mostly in the surface course and went down. The result: a superficial, much less expensive repair is required. In short, the British team found that well-built, thick HMA pavements performed well. "The most significant finding in this report is that there was no distress in the base — none — zero — zip," commented Jim Huddleston, executive director, Asphalt Pavement Association of Oregon. Concept already proven over time Researchers have discovered that in some locations, certain pavements have been functioning as Perpetual Pavements — and are performing very well. It's useful to consider a study conducted by the University of Washington on a 300-mile stretch of Interstate 90 from Spokane to Seattle. Over a range in age from six to 35 years, none of the pave- ments on 1-90 have been rebuilt due to structural problems. In eastern Washington, which has a cold, dry climate, the asphalt layers in the pavements ranged from six to 14 inches in thick- ness. The time to resurfacing has averaged 12 years, using tech- nology that predated the development of Superpave and the introduction of SMA to this country. In western Washington, HMA pavements are thicker, because Seattle -area traffic is much heavier. Pavements are 14 to 19 inches thick and range in age from 23 to 29 years old. The average time to resurfacing was 18.5 years — again, using pre-Superpave technology. The second resurfacing has not occurred for these pavements. The Baltimore Beltway in Maryland provides another good example. The average daily traffic (ADT) is 175,000 vehicles per day with 19 percent trucks. The pavement section comprises 11.5 inches of a strong base layer with large aggregate under 2.5 inches of a dense -graded mix topped by two inches of SMA with 3/4-inch top -size stone. The total HMA pavement thickness of 16 inches will preclude any bottom -up fatigue cracking — and the choice of an SMA surface mix has effectively prevented any significant rutting. Observation after four years of performance shows that the pavement rutting was on the order of 1/8-inch. Research funded by Flexible Pavements of Ohio examined pavement performance on four Interstate routes in the state. Proving that Perpetual Pavements have been in use for some time, the researchers found that the HMA pavements provided up to 34 years of service without the need for expensive reha- bilitation or reconstruction. And an examination of life cycle costs for these roads showed that HMA pavements produced only small incremental increases in present worth as overlays were added. Advantages of Perpetual Pavement "One obvious advantage of Perpetual Pavement is its lower life cycle cost," says Newcomb. "It has a lower life cycle cost than conventional asphalt or concrete pavements." Mark Buncher, director of field engineering at the Asphalt Institute, puts it this way: "Building a Perpetual Pavement may have a slightly higher initial cost versus a conventional flexible pavement, but it still will have a significantly lower initial cost than a comparably designed Portland Cement Concrete (PCC) pavement section. By never having to reconstruct the pavement system and only having to replace the surface peri- odically, a Perpetual Pavement will have a lower net present value in any life cycle cost analysis when compared to a Portland Cement Concrete pavement." Moreover, HMA surface repairs are faster than any alternative. "You can mill and replace asphalt in an overnight process," says Huddleston. "By contrast, base reconstruction can take years. The idea that people design pavement for 20 years and then have to rebuild it completely is a concept that has outlived its useful life. We have the technology to do better than that." State DOTs like the concept of Perpetual Pavements and they want to build them, says Huddleston. "The concept makes a lot of sense to them and it's being well received," he says. "Some DOT personnel are not yet comfortable with their level of knowledge of the Perpetual Pavement. The model we're recommending, therefore, is that the DOTs team up with a uni- versity, representatives of industry, or a recognized pavement expert to come up with a design, a set of specifications that will work." At the Illinois Asphalt Pavement Association (IAPA), Marvin Traylor, director of engineering and research, is very enthusiastic about Perpetual Pavements. "The advantage of a Perpetual Pavement is that you can take care of it from the top," says Traylor. "You don't have full -depth patches, and you don't have barricades that are left up for weeks at a time. " "You never have to shut down your lanes during rush hour," says Traylor. "You can mill off the surface at night, put a new surface down, and open it up. And we wouldn't have these terrible bottle- necks that we have in urban areas because the concrete is being recon- structed. You're not interrupting traffic and your costs are much reduced because you're simply taking off two inches and putting back two inches of HMA." In Illinois, Traylor says a joint task force of the state DOT and IAPA worked together to develop a Tong -life asphalt pavement design procedure. "The com- mittee developed a specification and cross-section for extended -life Hot Mix Asphalt pavement," says Traylor. "And the industry in Illinois looks forward to hav- ing a contract to demonstrate its ability." Alik 1 NAPA aria.% ail MEOW NATIONAL ASPHALT PAVEMENT ASSOCIATION BLACK AND GREEN Sustainable Asphalt, Now and Tomorrow air Ill allow AIP :aat . ` +. 0 lb all. 4 ' 1` 'kV all d w all al 4 a at l%;aa all la t* all all aq,l is ar� all af al Lall . z:+R ` TIC`Y RwR�s 9i 1 T i4► f_ ru alf- all Y ? r_ Lail 4411104 -_'IF " f all all q �_- ri. Ally o is x--. Y (a� _ iall _ A i t- _ ;' _ 1 4all _ _ i. Y Q _ •lia.,L all i vKrrss�� �t 6a _all all. — all tr — rt as 'all ' ►.." st4 all AWN x. "m_ NATIONAL ASPHALT PAVEMENT ASSOCIATION Printed on Recycled Paper Imaa BLACK AND GREEN Sustainable Asphalt, Now and Tomorrow Long before "sustainability" became an eagerly pur- sued part of the American business plan, the asphalt industry initiated research and field practices that have constantly enhanced the viability of asphalt as an environmentally sound building material. To date, the monumental accomplishment of this initiative lies in recycling. Asphalt is the most recycled material in America. About 100 million tons of old pavement are reclaimed every year, with about 60 million tons reused in new asphalt mixes, and some 40 million used in other pavement -relat- ed applications, such as aggregate road base.' Asphalt pavement is unique not only in the volume recycled, but also its renewability. It is com- prised of approximately 95 percent aggregates (stone, sand and gravel) and about 5 percent asphalt cement. When asphalt pavement is reused in a new asphalt mix, the old asphalt cement is rejuvenated so that it becomes an active part of the glue that holds the new pavement together, just like the old aggregate becomes part of the aggregate content of the new mix. These singular properties make asphalt a uniquely renewable pavement. Powering the trend to recycling/reusing asphalt is economics. Decades of research and engineering have improved the cost efficiency of converting old asphalt into a reusable resource that has tangible value. Today, pavement engineers, government agencies and contractors regard old asphalt as an asset, not waste, and the trend to recycling and reuse continues to gain momentum as a result. The industry has worked on other technologies that reduce air emissions including greenhouse gases and other contributors to climate change. These technologies include warm -mix asphalt, •...........••.•...............0000000 with lower emissions due to reduced temperatures, and long life pavements which reduce greenhouse gas emissions by reducing the frequency of repair and replacement. And modern asphalt technology has delivered asphalt pavement designs that actually enhance the quality of stormwater runoff even as they improve driving safety by reducing the amount of spray pro- duced by vehicle tires. Past, current and future advancements in asphalt as an environmentally sustainable paving material are especially important because asphalt is such a primary component of America's transporta- tion system and because the quantities of material used annually are so large. Of the 2.6 million miles of paved roads in the United States, over 94 percent are surfaced with asphalt. Approximately 85 percent of the nation's airfield pavements and 85 percent of the parking lots are also surfaced with asphalt. There are about 4,000 asphalt mixing plants located in the United States and the industry employs, directly or indi- rectly, 300,000 U.S. workers. Because of the vast extent of use of this material, even small changes in asphalt pavement technology can make a big differ- ence in terms of greenhouse gas emissions. �•SSL •••••••••••••••••••••••_11•_•_•. a 0 0 • • • • 0 0 0 0 0 0• o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o U 0 0 SUSTAINABLE ASPHALT, NOW AND TOMORROW • 2 The Road Ahead 3 Converting to Warm -Mix Asphalt 4 Doubling the Use of Reclaimed Materials in Asphalt Pavements 5 Expanding Implementation of Perpetual Pavement ' 7 Accelerating Appropriate Use of Porous and Open -graded Pavements 8 Conclusion 9 References �• • • • . • • • THE ROAD AHEAD None of the advancements in asphalt tech- nology would have been possible without a vibrant research and technology deploy- ment program. Leading the asphalt research effort is the National Center for Asphalt Technology (NCAT) in Auburn, Alabama, which originally was endowed by industry and today is directed by a public -private partnership. With its 1.7-mile pave- ment test track and its 40,000-square-foot research facility, NCAT conducts a productive, $ 5 million per year research program that focuses on innova- tions that directly affect and improve the roads we drive on every day. An important aspect of the industry's research program is that it is based on partnering. Partners in current and past initiatives include the National Asphalt Pavement Association (NAPA), the Federal Highway Administration (FHWA), the Federal Aviation Administration (FAA), the American Association of State Highway and Transportation Officials (AASHTO), the state Departments of Transportation (DOTs), the Transportation Research Board (TRB), the U.S. Army Corps of Engineers, the Environmental Protection Agency (EPA), related industry associations, the Occupational Safety and Health Administration (OSHA), the National Institute for Occupational Safety and Health (NIOSH), and the labor unions. There is also a broad range of international partners with whom the industry shares knowledge, conducts joint research, and cooperates on industry matters. One of the first breakthroughs in asphalt pave- ment technology achieved by this partnership was Superpave, a pavement design system that has enhanced pavement performance and durability in many ways. It was developed with federal funding under the Strategic Highway Research Program (SHRP) in the late 1980s and early 1990s. Superpave has become so widely accepted that use of the term is actually disappearing — what used to be called the Superpave design system is now the norm for designing asphalt pavements in much of the U.S. Another example of partnering was the initia- tive that began in the late 1980s in which NAPA worked with EPA on research into air emissions, including greenhouse gases from asphalt plants. The studies showed that emissions from asphalt plants are low and well controlled; they resulted in EPA declaring that asphalt plants are not major sources of hazardous air pollutants.2 Nonetheless, the industry continued to work to reduce emissions. In fact, total emissions from asphalt operations decreased by 97 percent from 1970 to 1999, while production of asphalt pave- ment material increased by 250 percent.' The industry is proud of its record of environmental stewardship and its proactive position of continu- ously reducing emissions, including greenhouse gas emissions. As impressive as our gains have been in recent years, we can still achieve significant gains in addressing climate change in the coming years by accelerating research and deployment of technolo- gies that reduce greenhouse gas emissions. We can increase use of warm -mix asphalt to represent the majority of all the pavement material produced in the U.S.; we can double the reuse/recycling of asphalt pavements; we can make Perpetual Pavements the standard design method; and we can have porous pavements accepted as a best manage- ment practice for reducing stormwater runoff and improving water quality. More information about these strategies follows. • SUSTAINABLE ASPHALT, NOW AND TOMORROW CONVERTING TO WARM Mix ASPHALT arm -mix technologies allow for produc- tion and placement of asphalt pavement material at lower temperatures than con- ventional hot mix technologies. Conventional asphalt pavement material is produced at around 320° F and warm mix is typically produced at tem- peratures ranging from 280° F down to 212° F.4 The potential for warm mix has won broad support among road managers and contractors. In five years following the first public demonstration of warm mix in the U.S. in 2004, scores of warm mix proj- ects have been constructed in 40 states. Warm mix was originally explored for its envi- ronmental benefits, which include reduced fossil fuel consumption and reduced emissions, including greenhouse gas emissions. Contractors and agencies have also discovered numerous construction and performance benefits, including the potential to extend the paving season in northern climates, the potential to store pavement mix for longer periods, a longer window of opportunity for compacting pavement, and increases in recycling rates. Running warm mix can reduce energy con- sumption during the manufacturing of the asphalt _ pavement mixture by an average of 20 percent, which decreases total life -cycle greenhouse gas emis- sions by 5 percent. In terms of greenhouse gas emissions, this equates to cutting 1 million tons of asphalt production annually. Combining warm mix with reuse/recycling yields even greater benefits. Warm mix with 25 percent reclaimed asphalt pave- ment could potentially offset asphalt pavement life- ii SUSTAINABLE ASPHALT, NOW AND TOMORROW cycle greenhouse gas emissions by 15 to 20 percent. The potential for total savings in greenhouse gas emissions using both warm mix and recycling is about 3 million tons per year. NAPA, FHWA, AASHTO, and researchers cre- ated a Technical Working Group whose purpose is to evaluate warm -mix technology performance, quantify environmental benefits, develop perform- ance specifications, provide technical guidance, and disseminate information. The partnering approach has been of immense support to efforts to deploy warm mix. So far, implementation has proceeded with vir- tually no complications.5' 6' 7' 8' 9' 1° Demonstration projects, trials, and test projects have included the full variety of asphalt mixture types. At least 10 states have adopted permissive specifications, clear- ing the way for contractors to produce and place the mix at low temperature as long as it meets all other criteria. Experience with applied research and technolo- gy development suggests that warm mix may make it possible to increase the rates of reuse/recycling even more. Applied research on this topic will be helpful in speeding the rate of acceptance of com- bining the two technologies. Another opportunity for applied research is full documentation of emission reductions, with specif- ic focus on greenhouse gas emissions. Such research would also assist agencies in taking full advantage of warm mix to meet air quality guidelines. DOUBLING THE USE OF RECLAIMED MATERIALS IN ASPHALT PAVEMENTS The use of reclaimed asphalt pavement (RAP) has been widespread for about 30 years." Asphalt pavement is Americas most recycled material. Every year, more than 100 million tons of asphalt pavement material is reclaimed and virtually all of it is reused or recycled into new pavements. W aterials from other industries, including roofing shingles and ground rubber from used tires, can also be beneficially incorporated into asphalt pave- ments. The key to this is sound engineering, design, and technology. Increased use of RAP as a percentage of the total asphalt mix can significantly reduce green- house gas emissions by eliminating the significant fuel consumption required to acquire and process raw materials for virgin mix. Currently, RAP makes up 12 percent of the average asphalt mix by vol- ume, with the remainder comprised of virgin aggre- gate and asphalt cement. Contributing to this average are states that rou- tinely use 30 percent RAP and states that permit minimal use. If we increase RAP usage to 25 per- cent of the average mix, we will reduce total life - cycle greenhouse gas emissions by 10 percent, which equates to 2 million tons offset annually. One of the unique qualities of asphalt cement is that it is rejuvenated when RAP is incorporated into new pavement, becoming an integral part of the binder. This is referred to as the highest and best use. In view of the high reuse/recycling rate in lead states, including a preponderance of evidence that the quality of asphalt pavements incorporating RAP is equal to or better than pavements using all virgin materials, there is ample opportunity to double the quantity of RAP used within five years. Part of the challenge is to encourage agencies in rural areas to allow milling on pavements prior to the placement of asphalt overlays. This will provide more material for recycling in areas where RAP is scarce, and it will improve the performance of the rehabilitated pavement by removing distresses from the existing surface. FHWA has organized the RAP Expert Task Group (ETG), which brings together stakeholders from government, industry, and academia to investi- gate obstacles to increasing RAP use. As part of this mission, the ETG has identified states with particu- larly high and particularly low levels of reuse/recy- cling. The ETG is also charged with achieving the desired increases through technology transfer/accel- erated deployment strategies, and eliminating artifi- cial and arbitrary barriers to increased recycling in favor of performance -based pavement criteria. There are also opportunities for applied research, including quantifying the environmental benefits of increased RAP use, developing technologies and pro- cedures to recycle high percentages of reclaimed material, developing technologies and procedures to better preserve the aggregate gradation in RAP, and improving performance testing methods and specifi- cations for use of RAP and roofing shingle mixtures. All these activities would contribute to increasing the overall rate of recycling and therefore provide reduc- tions in emissions of greenhouse gases.'2 Economic Sustainability Reuse/recycling is not only an environmentally sustainable practice, it is an economically sustain- able one. NAPA estimates that we have 18 billion tons of asphalt pavement already in place on America's roads and highways. Because of the abili- ty to reuse and recycle this material indefinitely, our highways are a resource for future generations. Not only are our roads a primary engine of the econo- my, they have a high residual value as a source of construction materials. As a note, the process of reclaiming and processing these materials has a very low environmental impact. SUSTAINABLE ASPHALT, NOW AND TOMORROW ERPANDING IMPLEMENTATION OF PERPETUAL PAVEMENT erpetual Pavement is the name given to an asphalt pavement that is designed not to fail. Construction is in layers whose properties serve a combination of different functions; they all add up to an extraordinarily long-lasting pavement. Surface distresses may occur eventually, but they do not pen- etrate deep into the pavement's structure. Routine maintenance involves infrequent milling of the top layer for recycling, then placing a smooth, quiet, durable, safe new overlay. A Perpetual Pavement never needs to be completely removed and replaced. In the world of pavements, this is the ultimate in economic and environmental sustainability. Perpetual Pavements can mitigate climate change by reducing greenhouse gas emissions, both now and for generations to come. Perpetual Pavements reduce greenhouse gas production in several ways. 1 Since only the surface is renewed, the base structure stays in place, thereby significantly reducing greenhouse gases associated with vir- gin raw materials acquisition and placement. 1 Greenhouse gas emissions associated with complete removal and replacement of pave- ments that have reached the end of their useful life is avoided. 1 Greenhouse gas emissions associated with construction delays are greatly reduced because maintenance and rehabilitation can be done quickly in off-peak hours, unlike the remove - and -replace option, which necessitates 24-hour road closures. Limiting closures to off-peak hours can reduce delays for road users by at least a factor of 12, i.e., a 2 1/2-minute delay versus a 30-minute delay. SUSTAINABLE ASPHALT, NOW AND TOMORROW Perpetual Pavements are more cost-effective than traditional asphalt pavements while enhancing durability, performance, and long life. Reuse/recy- cling is part of the maintenance and rehabilitation process. 3 All these factors conserve construction materials and reduce greenhouse gases. Once the road is constructed, it becomes a per- manent asset within the transportation infrastruc- ture system. A Perpetual Pavement does not become a reconstruction problem for future genera- tions. Perpetual Pavements can also keep roads smoother. Significant fuel savings are associated with smooth pavements. It has been documented under tightly controlled conditions that driving a heavily loaded truck on a smooth road consumes about 4.5 percent less diesel than driving on a rough one.14 The history of Perpetual Pavements goes back to the 1960s, although the term was not used until around 2000. Full -depth asphalt pavements first - achieved wide acceptance in the 1960s as a way of minimizing materials use and construction costs." At that time, it was assumed that the design would result in a "20-year design life," but experience has shown that such pavements have lasted for over 40 years with no sign of structural failure. Engineering studies in the states of Kansas,' Minnesota,' Ohio,17 Oregon,' and Washington18 have validated these observations. Beginning in 1999 and 2000, asphalt pave- ment researchers initiated efforts to understand the engineering features and performance characteris- tics of Perpetual Pavements. Research has been con- ducted at NCAT, the Asphalt Institute, the University of California at Berkeley, the University of Illinois, and other leading institutions in the U.S. and around the world. The research has led to the development of materials, design methods, and performance criteria to enable agencies to design pavements that ensure long life without wasting materials due to overdesign. There are already many pavements around the United States that fit the Perpetual Pavement defi- nition. In recognition of that fact, in 2001 the asphalt industry created a program to identify Perpetual Pavements and honor the agencies that have designed and maintained them. Fifty-nine Perpetual Pavement Awards have been presented through 2008. In addition to working toward the full integra- tion of Perpetual Pavement technologies into pave- ment design guides, the asphalt industry will con- tinue to pursue research to advance Perpetual Pavement best practices. There are currently two national studies on Perpetual Pavement through the National Cooperative Highway Research Program (NCHRP) focused on the engineering characteristics that will be critical to the design of long -life pavements. Pavements have been constructed with instruments embedded in the various layers to ascertain their responses to truck loadings at a variety of locations. These include the NCAT Pavement Test Track and the Minnesota Road Research Project, as well as in highways located in Kansas, Ohio, Pennsylvania, Wisconsin, and other states. These will provide cru- cial information on the field behavior of Perpetual Pavements. Significant opportunities for applied research on Perpetual Pavements include an investigation of high -stiffness base materials, which have the poten- tial to reduce both costs and greenhouse gas emis- sions, and research on the impact of these long -life pavements on climate change, specifically green- house gases. In summary, Perpetual Pavements conserve natural resources, reduce life -cycle costs, save fuel, and reduce fuel consumption and greenhouse gas emissions. SUSTAINABLE ASPHALT, NOW AND TOMORROW ACCELERATING APPROPRIATE USE OF POROUS AND OPEN -GRADED PAVEMENTS orous and open -graded asphalt pavements have been shown to have a dramatic beneficial effect on water quality. These pavements have been used widely for over 30 years with an excellent record of success. Open -graded pavement is made with same -size rocks, creating a web of interlocking pores that allow water to flow through the surface. ° Open -graded pavements are used mainly in two types of applications. First, open -graded friction courses are widely used for surfacing roads and high- ways. The pavement layer directly beneath this is impermeable. During a rainstorm, instead of pool- ing on the surface or bouncing off it, rain drams through the surface and out to the sides. Splash and spray are greatly reduced, enhancing safety. Second, porous pavement systems are stormwa- ter management tools with an open -graded surface over a stone recharge bed. The system is designed and constructed to collect stormwater, which then infiltrates into the ground Porous pavement sys- tems are used mostly for parking lots, but they have also been used successfully for roads in communi- ties like Pringle Creek in Salem, Oregon.20 Both applications can be used to improve water quality. Porous asphalt surfaces allow roads and highways to function as linear stormwater manage- ment systems. Porous parking lots store stormwater, reduce runoff, promote infiltration and groundwa- ter recharge, allow evaporative cooling of the atmosphere, diminish erosion on stream banks, reduce particulates in stream water after storms, and improve water quality.' SUSTAINABLE ASPHALT, NOW AND TOMORROW Porous asphalt pavements are accessible and affordable. They can be produced and constructed by any qualified contractor. Open -graded highway surfaces have additional environmental and safety benefits. They reduce road noise significantly.22, 23. 24, 25, 26 Texas DOT reported that replacing a conven- tional surface with open -graded friction course in a high -accident area reduced wet -weather accidents by 93 percent and reduced fatalities by 86 percent.27 With respect to porous pavement systems for stormwater management, some local authorities may allow the construction of porous pavement systems but still require total redundancy with the use of conventional stormwater management struc- tures. Applied research documenting the effective- ness of porous pavements, together with a program of continuing education, could be helpful in expanding the use of these pavements and avoiding using them inappropriately. The industry and partners will use applied research, demonstration projects, open houses, Web -based tools, and other continuing education efforts to accelerate the deployment of porous asphalt solutions in the months and years to come. Industry will also assist federal and state agencies in developing design guidance for porous asphalt applications. And we will look for opportunities to document the environmental effectiveness and cost benefits of porous asphalt pavement, improve mate- rials and mix designs, and evaluate highways as lin- ear stormwater management systems. CONCLUSION The engineers, scientists, contractors and managers who guide the development of asphalt pavement have made it one of the most environmentally advanced building materials in the world by constantly improving its cost effec- tiveness and safety. By extending pavement life — by improving materials, designs, or best practices — these profes- sionals reduce the cost to the environment and to the taxpayer. By improving the desirability of reclaimed asphalt in new mixes, they have reduced the cost of the mix and the demand for virgin asphalt cement and virgin aggregates. Going forward, the industry and its partners will pursue the same mandate. It is not enough that the asphalt industry is capable of cutting green- house gas emissions or reducing energy usage or enhancing the quality of stormwater runoff Solutions must also make sense economically for the agencies and companies that buy them. Going forward, there will be more research, not less. As we conceive and prove new warm -mix tech- nologies, more pavement managers will use warm mix in more applications. As we document the long life and long-term cost effectiveness of Perpetual Pavement, more engineers will adopt this design system for high -load, high -volume roads. As we test and verify new mix dynamics for porous asphalt, road managers will find more ways to use it. That is how we will make warm -mix asphalt the primary pavement material — and reduce energy consumption and greenhouse gas emissions in the process. That is how we will double the reuse/ recy- cling of asphalt pavements — and reduce energy consumption, emissions, and the use of virgin nat- ural resources. That is how we will make Perpetual Pavements the standard design method for road- ways — and completely redefine the life -cycle expec- tations and economics of highways in America. And that is how we will make porous pavements accepted as a best management practice for reduc- ing stormwater runoff and improving water quality. In responding to these challenges, the asphalt pavement industry and its partners will continue to improve the environmental performance of asphalt, already one of the most sustainable pavement mate- rials on earth. REFERENCES 1. Hansen, K., and D. Newcomb, RAP Usage Survey, National Asphalt Pavement Association, Lanham, Mai yland, August 2007. 2. Federal Register, February 12, 2002, pp. 6521 ff. (http //frweb ate access oov/c�r- bin/ getuage cgi?dbname=2002 register&position=all p&age=6521, accessed March 26, 2009.) Also, Federal Register, November 8, 2002, pp. 68124 ff. (http: //frwebgate.access.gpo.gov/cgi- brn/getpag_e.cgi?dbname=2002 register&position=all &page=68124, accessed March 26, 2009.) 3. Cervarich, M., Report to Members 2001, National Asphalt Pavement Association, Lanham, Maryland, 2002. 4. Prowell, B. D , and G. C. Hurley, Warm -Mix Asphalt: Best Practices. Quality Improvement Series 125, National Asphalt Pavement Association, Lanham, Maryland, 2008. 5. Prowell, B. D., G. C. Hurley and E. Crews, Field Performance of Warm Mix Asphalt at the NCAT Test Track. Transportation Research Record 1998 Transportation Research Board, Pp 96-102. Washington, D C., 2007. 6. Acott, M., Warm -Mix Asphalt in the U.S.A., State of the Practice Eurasphalt and Eurobitume 4th Congress, Copenhagen, Denmark, 2008. 7. D'Angelo, J., E Harm, J. Bartoszek, G. Baumgardner, M. Corrigan, J. Cowsert, T. Harman, M Jamshidi, W. Jones, D Newcomb, B. D Prowell (Report Facilitator), R. Sines, and B. Yeaton, Warm -Mix Asphalt: European Practice. International Technology Scanning Program, Federal Highway Administration, February 2008. SUSTAINABLE ASPHALT, NOW AND TOMORROW L�oLt�#tJ04'i�LE .. _ 8. Davidson, J., "Evotherm R Trial - Ramara Township," McAsphalt Industries Limited, December 12, 2005. 9. Harder, G , Y. LeGoff, A. Loustau, Y. Martineau, and B. Heritier, "Energy and Environmental Gains of Warm and Half -Warm Mix: Quantitative Approach." Transportation Research Board 87th Annual Meeting, Washington, D.C., CD-ROM, 2008. 10. MacDonald, C., Warm -Mix Asphalt• Contractors' Experiences. Information Series 134, National Asphalt Pavement Association, Lanham, Maryland, 2008. 11. McNichol, D , Paving the Way: Asphalt in America. National Asphalt Pavement Association, Lanham, Maryland, 2005. 12 Federal Highway Administration, American Association of State Highway and Transportation Officials, Asphalt Institute, National Asphalt Pavement Association, and National Stone, Sand, and Gravel Association. National Asphalt Roadmap - A Commitment to the Future. NAPA Special Report 194, Lanham, Maryland, 2007. 13. Perpetual Bituminous Pavements, 2001. Transportation Research Circular 503, Transportation Research Board, Washington, D C. 14. Sime, M., et al , WesTrack Track Roughness, Fuel Consumption, and Maintenance Costs. Tech Brief, Federal Highway Administration, Washington, D.C., January 2000. 15. Cross, S. and R. Parsons, Evaluation of Expenditures on Rural Interstate Pavements in Kansas, Kansas University Transportation Center, University of Kansas, Lawrence, Kansas, February, 2002. I REFERENCES 16. Lukanen, E , Performance History of HMA Pavements with Aggregate Base and Portland Cement Concrete Pavements, Minnesota Asphalt Pavement Association, New Brighton, Minnesota, 2002. 17. Gibboney, W., Flexible and Rigid Pavement Costs on the Ohio Interstate Highway System, Westerville, Ohio, 1995. 18. Transportation Research Board, Pavement Lessons Learned from the AASHTO Road Test and Performance of the Interstate Highway System, Transportation Research Circular E-C118, Washington, D C., July 2007. 19. Hansen, K. Porous Asphalt Pavements for Stormwater Management, Information Series 131, National Asphalt Pavement Association, 2008. 20. Estes, T. Green Paving Grows Beyond Parking Lots. Better Roads Magazine, Des Plaines, Illinois, October 2007. 21. University of New Hampshire Stormwater Center. (2007). University of New Hampshire Stormwater Center 2007Annual Report. Durham, New Hampshire: UNH Stormwater Center. 22. Hansen, D I , R.S. James, and B Waller, Kansas Tire/Pavement Noise Study, Asphalt Pavement Alliance, Lanham, Maryland, June 2005. 23. Hansen, D I , R.S. James, and B. Waller, Oklahoma Tire/Pavement Noise Study, Asphalt Pavement Alliance, Lanham, Maryland, January 2005. 24. Hansen, D.I., R. S. James, and B. Waller, Tire/Pavement Noise Study for Arkansas APA, Asphalt Pavement Alliance, Lanham, Maryland, January 2005. 25. Newcomb, D , and L Scofield, Quiet Pavements Raise the Roof in Europe, HMAT Magazine, National Asphalt Pavement Association, Lanham, Maryland, September/October 2004. 26. Reyff, J., et al., I-80 Davis OGAC Pavement Noise Study: Traffic Noise Levels Associated With an Open Grade Asphalt Concrete Overlay. Prepared for California Department of Transportation by Illingworth & Rodkin, Inc., Sacramento, CA, December 1, 2002. 27. Rand, D. PFC Mixes Can Reduce Wet Weather Accidents, HMAT Magazine, National Asphalt Pavement Association, Lanham, Maryland, January/February 2007. 28. Barrett, M. E., & Shaw, C. B. (2007). Stormwater Quality Benefits of a Porous Asphalt Overlay. Transportation Research Record: Journal of the Transportation Research Board. i SUSTAINABLE ASPHALT, NOW AND TOMORROW • Bill Rosener Executive Vice President Asphalt Paving Association of Iowa 116 Clark Avenue Suite C Ames, IA 50010 O: 515.233.0015 C: 515.450.0100 E: billr@apai.net W: www.apai.net