The asphalt pavement association of oregon is a nonprofit trade association representing contractors and associated firms. Porous asphalt pavements offer developers and planners a new tool in their toolbox for managing storm water. Porous asphalt pavements are being used to reduce or eliminate storm water runoff from parking lots and other such facilities. Download this free whitepaper to learn what separates permeable pavement from porous asphalt. Design and select the thickness of a porous asphalt pavement. The differences of permeable pavement and porous asphalt. Porous asphalt pavements are typically built over an uncompacted subgrade to maximize infiltration through the soil. The bottom of the base should be level to enhance distribution.
The crushed aggregate filter layer aids with pollutant removal and provides stability for the stone reservoir layer during application of pavement. Porous asphalt pavements offer an alternative technology for storm water management. Permeable pavement is a pavement type with a porous surface that is composed of concrete, open pore pavers or asphalt with an underlying stone reservoir. The void space of porous asphalt is approximately 16%, as opposed to two to three percent for conventional asphalt. Porous asphalt pavement pap is an innovative technology, in which rain water directly percolates to the ground water without any surface runoff. Porous asphalt is the same as regular asphalt except it. Porous asphalt pavements offer developers a new option for managing storm water. Porous asphalt pavements, used mostly for parking lots, allow water to drain through the pavement surface into a stone recharge bed and infiltrate into the soils below the pavement. The hma pavement mix type selection guide provides designers with methods for selecting appropriate mix types while considering factors such as traffic, environment, subsurface pavement structure, existing pavement condition and preparation, and economics. Porous asphalt paving cost and environmental benefits. Porous asphalt the specs october 28, 2014 washington asphalt paving association. History of porous asphalt pavements porous asphalt mixes developed in 1930s and 1940s by state dots using mixes to reduce runoff in 1970s geotextiles developed in 1979 current design process used since 1980. The base material shall be free of contaminates to allow for water passage. Structural design of porous asphalt pavements tuesday, july 17.
Porous asphalt for storm water management its not just for parking lots anymore ohio asphalt paving conference february, 2008 by gary thompson, p. Porous asphalt pavement refers to the compacted mix of modified asphalt, aggregate, and additives. Porous asphalt can be used in replace of traditional stormwater management. A study conducted at villanova university on two permeable pavements, porous asphalt and pervious. Porous asphalt designed so that after laying and compacting, they form a surface with a voids more than 20 percent. Porous asphalt pavements california coastal commission.
Design and construction of porous asphalt pavements. Design of longlife flexible pavements for heavy traffic. Porous or permeable friction courses pfc are hot mix asphalt hma mixtures placed at the surface of an asphalt pavement structure in a thin layer to produce several benefits for the traveling public in terms of safety, economy, and the environment. It is designed as a companion piece to napas popular porous asphalt pavements for stormwater management. Regular inspection and maintenance guidance for porous. Porous asphalt the specs tim horton, skillings connolly jessica knickerbocker, city of tacoma mark a. Sandstone, granite, chert, traprock, ore tailings, slag or other similar noncarbonate materials. A range of processesmethods are available for the recycling. Pavements and surface materials page 2 slabs and paver stone embedded in reinforced concrete are examples of rigid pavement. Both the history of the technology and the latest largescale projects, including innovative uses of porous pavements, are discussed. Applicability porous asphalt allows for runoff volume and rate control, plus pollutant reductions. The right choice for porous asphalt porous pavements. These characteristics in a permeable solution are maintained whilst being free draining removing risks of standing water.
Structural design guidelines for porous asphalt pavements. Difference between permeable pavement and porous asphalt. Astm test c1701 should be used to indentify the needed flow through the porous pervious pavement layer. Porous asphalt asphalt pavement association of oregon. Solids, as well as some of the metals, were believed to be trapped in the porous asphalt overlay. Article information, pdf download for development of structural design. Porous asphalt pavement is an environmentallyconscious and sustainable paving solution that can offer significant longterm cost efficiency. Permeable pavement fact sheet information for howard.
Hma hot mix asphalt complies with napa specifications for porous applications polymer additive, 6%9% asphalt cement binder. All materials in the roadway section are permeable, allowing free flow of water to subgrade for infiltration or other routing. Porous asphalt pavements with stone reservoirs are a. These pavements, used mostly for parking lots, allow water to drain through the pavement surface into a stone recharge bed and infiltrate into the soils below the pavement. While the specific design may vary, all permeable pavements. Pervious concrete is a rigid pavement while porous asphalt, permeable pavers, flexible grids and gravel are all flexible pavements. Speight phd, dsc, in asphalt materials science and technology, 2016. Porous asphalt is pervious asphalt that allows water to penetrate into an underground storm water management facility. Detailed design, construction, use, and performance information is provided for porous asphalt, pervious concrete, permeable interlocking concrete pavement, and grid pavements. Specific details on hydrological design are beyond the scope of this report.
Click here to download a free copy of the publication in pdf format. Mar, 2020 asphalt has always been and continues to be the pavement of choice for america. Porous asphalt pavement is an alternative technology that differs from traditional asphalt pavement designs, that the pavement permits. Porous asphalt pavements allow designers to introduce more. Porous asphalt is a developing in road surfacing technology. The selected gradation follo ws national asphalt pavement a ssociation 8, for porous asphalt paving mixtures for 19 mm aggregate maximum sizes and go outside of. If porous pavement is sealed, additional stormwater treatment may be required. Pavements and surface materials page 1 n o n p o i n t e d u c a t i o n. Aggregate for wearing course is typically 14 to 38, though larger gradations have been used successfully. Porous asphalt pavement also reduces and control surface runoff of surrounding area. Coarse aggregate shall be free from clay balls, organic matter, deleterious substances. Asphalt paving design guide asphalt pavement association of. To keep the system clean throughout the year and prolong its lifespan, the pavement surface should be.
The asphalt institute in college park, maryland has issued a asphalt thickness and design, manual that suggests that asphalt thickness for roads be based on the following three factors. National asphalt pavement association, porous asphalt pavement, national asphalt pavement association, lanham maryland, 2003. All other installations cited in this article are asphalt pavements. This technical brief provides an overview of the benefits, limitations and applications of porous asphalt pavements with stone reservoirs. If a hydraulic connection is possible, porous asphalt pavement systems shall be located per the requirements of wdnr conservation practice standards 1002, site evaluation for stormwater infiltration, and. Porous asphalt pavement wisconsin asphalt pavement association. Whenever vacuuming adjacent porous pavements repairs may be needed from cuts of utilities. Porous asphalt pavements allow for land development plans that are more thoughtful, harmonious with natural processes, and sustainable. Porous asphalt the specs washington asphalt pavement. Repairs using standard asphalt should not exceed 15% of total area. Porous asphalt pavements allow for land development plans that are more. Rainwater flows down through the opengraded mix layers into the stone reservoir where it can then infiltrate into the subgrade.
Hma pavement mix type selection guide introduction background our nations roadway system is critical to our economy. For pervious concrete in soils with high infiltration rates, its possible that you wont need any rock because the material is such that the rigid pervious concrete will be structurally sound on the native soils. A porous system is going to have more void space in its cross section than a pervious system. Porous pavements can be constructed using either asphalt or concrete materials or in some cases, placed pavers. Porous asphalt pavement is an alternative technology that differs from traditional asphalt pavement designs, that the pavement permits fluid to pass freely through it. Permeable asphalt binder course permeable asphalt surface course with all asphalt pavements the surface course is designed to provide a smooth finish, with no trip hazards an appropriate level of slip and skid resistance. A variety of permeable pavement surfaces are available, including pervious concreteporous asphalt, and permeable grid pavers and interlocking concrete pavers. Design, construction, and maintenance guide order number is1. This design economizes porous asphalt installation costs while providing sufficient treatment area for the runoff generated from impervious surfaces. Porous asphalt pavements 2004 information series 1.
Dissolved oxygen refers to the level of free, noncompound oxygen. Projects use porous asphalt to meet postconstruction stormwater quantity and quality requirements. Electric arc furnace slag eafs and ladle furnace slag lfs are byproducts of the electric steelmaking sector with suitable properties for use in bituminous mixtures as both coarse and fine aggregates, respectively. Cahill associates has been involved in the design and construction of more than 200 porous asphalt pavements since the 1980s and have reported no failures of pavements for which proper design and construction practices were followed. Repairs can be made using standard non porous asphalt for most damages. Standard for pervious paving systems february 2004 page 9. Guidelines on construction and maintenance of porous.
Performance of porous asphalt pa was evaluated on a parking lot of the washington state university puyallup campus that included three pavement treatments in triplicate. Porous asphalt pavements use opengraded mixes placed atop a stone reservoir. The study of porous asphalt pavement with emphasis in. With 27 percent void space, porous pave delivers 5,800 gallons per hour per square foot permeability. Pdf laboratory performance of porous asphalt pavement. Monitoring porous asphalt stormwater infiltration and outflow. The pavement mix types targeted are ogfc, sma, and fineand coarsegraded dense mixes. Unhsc design specifications for porous asphalt pavement and. Porous asphalt the specs tim horton, skillings connolly jessica knickerbocker, city of tacoma. Use fibers and antistripping agents in binder to reduce draindown potential. Porous asphalt pavement, on the other hand, is a type of type porous pavement structure specifically designed to allow rainfall and runoff to flow into and through the pavement structure. Contrasts to common use of porous asphalt for a porous friction course pfc or open graded friction course.
Porous pavement operation and maintenance protocol general maintenance the primary goal of porous pavement maintenance is to prevent the pavement surface andor the underlying infiltration bed from being clogged with fine sediments. Permeable paving is a method of paving vehicle and pedestrian pathways to enable infiltration of stormwater runoff. Hma pavements serve in a multitude of traffic and environmental conditions, demanding that the materials and. In this research, the production of a porous asphalt mixture with an aggregate skeleton consisting exclusively of electric steelmaking slags using neither natural aggregates. The last layer consists of one or more layers of porous asphalt mixes with interconnected voids that allow water to flow through the pavement into the stone reservoir. Several applications use porous asphalt in parking lot lanes or parking stalls to treat runoff from adjacent impermeable pavements and roofs. Permeable paving techniques include porous asphalt, pervious concrete, paving stones, and manufactured grass pavers made of concrete or plastic. The focus is on the structural design procedure and its required inputs using the aashto 93 design method. Porous pavements are an alternative to traditional asphalt or concrete surfaces which may help alleviate some of these issues. Porous asphalt is an innovative road surfacing technology, which allows water to enter into the asphalt mixes beyond its continuous air voids.
Development of structural design guidelines for porous asphalt. Jul 20, 2010 ats construction testing an asphalt porous pavement parking lot at the kentucky horse park in lexington, kentucky. This study concentrates on porous pavements constructed using asphalt. At present, 94 percent of the roads in america are surfaced with asphalt and for those who know the benefits of asphalt, there is no substitute. Porous asphalt pavements technical bulletin figure 1. Cross section of typical porous asphalt pavement with stone reservoir image courtesy of fhwa unlike conventional pavements, porous asphalt pavements figure 1 are typically built over an uncompacted subgrade to maximize infiltration through the soil. This would apply to both permeability life and structural life. Furnish and place porous asphalt pavement courses in accordance with the contract documents andor as directed by the engineerincharge.
Porous asphalt pavements need to be washed with highpressure sprays or vacuumed to keep soil particles from collecting in and clogging the voids. Cost, intersection design, and porous pavements for commercial facilities. The dissolved fractions of copper and zinc were higher in the runoff from porous asphalt overlay. Porous pave has been proven in successful installations for a wide variety. Porous asphalt pavement faqs flexible pavements of ohio. The association and its members are dedicated to promoting asphalt pavements by developing pro. References ater services design and construction standards clean w. Porous asphalt pavements wetland studies and solutions. Porous pavements are asphalt or concrete pavement surfaces designed to allow moisture to flow through the surface into an underlying reservoir or into the subgrade soil bachtle, 1974.
Hot mix asphalt hma pavements constitute a large part of our nations surfaced roads. Use of this manual will result in improved asphalt pavement quality and performance. Permeable asphalt can be integrated into drainage schemes or be utilised as a complete system to help create a sustainable drainage system suds. Apao was formed in 1969 by a small group of asphalt paving contractors to develop improved specifications and products. Permeable pavement is a method of paving that allows stormwater to seep into the ground as it falls.
Porous pavement offers the potential to collect andor slow the rate of runoff from other impervious surfaces. May 02, 2017 porous asphalt pavement can be a valuable tool for business developers, municipalities and even homeowners who are interested in storm water management. Structural durability is a significant issue with tlpa. Table 1 summarizes many benefits and limitations of porous asphalt pavements. A permeable asphalt system provides an effective solution to mitigate the increase in impermeable surfaces associated with new developments and urbanisation. Many porous pavements have been constructed since the late 1970s. Stage the placement of the porous asphalt pavement after the. There are case studies of several examples of porous pavement installations that are still functioning well after 15 or 20 years. Performance and durability of porous asphalt mixtures.
Lavishly illustrated, the brochure serves as a useful introduction to the subject. Considerations for design and construction, as well as maintenance, are discussed. Porous asphalt itself provides for some pretreatment of runoff. A typical porous pavement has an opengraded surface over an underlying. Unhsc design specifications for porous asphalt pavement. Pavement surfaces shall have a permeability of eight inches per hour or grater with a slope porous pavement operation and maintenance protocol general maintenance the primary goal of porous pavement maintenance is to prevent the pavement surface andor the underlying infiltration bed from being clogged with fine sediments. Made with chips of recycled rubber, it is an ecofriendly, green building product. The porous asphalt pavement specified herein is modified after the national asphalt pavement association napa specification outlined in design, construction, and maintenance guide for porous asphalt pavements, information series 1 2003. When properly constructed, porous asphalt is a durable and cost competitive alternative to conventional asphalt.
Keep the porous asphalt pavement free of contamination from the construction operations. The aim of this study is to recharge ground water to underplaying aquifers and reduce risk of flood condition. Asphalt porous pavement is a green application that allows storm water to. Porous asphalt pavements can be recycled for use in thin surfaces. A porous asphalt pavement is constructed over a stone filled reservoir to collect and store storm water and to allow it to infiltrate into the soil between rainfalls figure 1. All permeable paving systems consist of a durable, loadbearing, pervious surface overlying a stone bed that stores rainwater before it infiltrates into the underlying soil. Filtering capability of porous asphalt pavements mdpi.
Download our free brochure to learn the difference of permeable pavement and porous asphalt. Such pavements have been proving their worth since the mid1970s. Permeable pavement fact sheet information for howard county, maryland homeowners. This allnew update of napas popular publication provides the latest information on these dualpurpose pavements. Vacuuming adjacent non porous asphalt can be effective at minimizing runon. Also considered as green pavement, it allows water to run through it rather than accumulate on it or run off of it. The unsalted, porous asphalt sections had a similar amount of bare pavement compared to salted, conventional asphalt sections the porous pavement over sand subgrade was more effective for ice control compared to the porous pavement on clay subgrade, porous asphalt on sand can infiltrate all or most of the runoff. The use of porous asphalt pavements has become more common in recent years as the requirements for stormwater runoff have become more stringent. Porous asphalt pavements is a fullcolor, sixpage executive summary brochure. This technique also can be used as additional way of storm water management. Take precautions as necessary such as washing truck tires, installation of silt fence, tarps on heavily traveled areas, etc.
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