Frequently Asked Questions

HMA remains the most economical paving material despite the recent increase in the price of petroleum. Comparison of equivalent designs and alternate bid items taken by the Ohio DoT show that HMA pavement is still less costly than a concrete pavement designed to carry the same load. This is one of the reasons 93% of all paved roads in the U.S. have an HMA surface.

For more information on the alternate bids taken by the Ohio DoT, read the April 2009 news item, "Asphalt alternate lower but project goes PCC" (PDF).

Properly designed and constructed HMA pavements are the most economical to maintain over the long term. A comparison study of Ohio’s Interstates has shown that original HMA pavements have been cheaper to maintain throughout their lives than concrete pavements and have never had to be reconstructed or replaced. Another reason 93% of roadway surfaces are asphalt. For more information on the comparative costs of maintaining pavements, see our study Economic Evaluation of Ohio’s Flexible and Rigid Interstate Pavements.

There really are many reasons to prefer an HMA pavement including: smoothness, quiet, stage construction, ease of maintenance, speed of construction, least user delay cost, ease of repair of utility cuts, no cure time, recyclability and now, that technology exists to design HMA mixtures to reliably perform under any conditions of load and environment, there is no longer any reason to consider anything else . for more information on these issues, visit Asphalt Roads.

Superpave is a system of material specifications and laboratory mix design methods based on performance criteria developed under the Strategic Highway Research Program (SHRP). Using the Superpave system, materials and mixes can be designed to reliably perform under any conditions of load and environment. The Superpave system is undergoing continuing development nationally. The Ohio DoT adopted Superpave for its heavy traffic applications as Item 442 of its 2002 CMS.

In many respects Hot Mix Asphalt (HMA) is the environmentally friendly paving material. First, HMA materials are 100% recyclable. Virtually all of the reclaimed Asphalt Pavement (RAP) that is removed from existing streets and highways is recycled into new HMA. Because this recycling of HMA is economical, it occurs without the need for government mandates or subsidies.

The use of Asphalt pavement can result in environmentally friendly, sustainable development as well. For more information on this subject visit the Asphalt Education Partnership website and

HMA also has been shown to consume less energy than other materials and systems. A study done by the Asphalt Institute indicated that a comparably designed HMA pavement required only about half the total energy to construct as a comparable portland cement concrete pavement.

Improvements in technology have been steadily reducing the airborne emissions from the production and placement of HMA. Dust from the drying of aggregates is the major emission and is now almost totally captured and recycled. Other emissions are primarily combustion products from the burning of fuel to heat the aggregates and fumes from hot asphalt itself. Fuel burners are now much more efficient, resulting in very complete combustion. Studies to date by the government and industry have shown emissions levels to be very low and have not identified any health hazard associated with exposure to asphalt fumes. Nevertheless , the industry continues to develop improved technology for reducing emissions and minimizing exposure.

To read articles relating to the environmental effects of HMA production, see below.

HMA Plants Removed from Sources Subject to MACT Standards
Clearing the Air - HMAT 2001
Tests Show Low Emissions

For more information on this subject, see the following publications of the Asphalt Institute:
PR-1, Environmental Applications for Hot Mix Asphalt;
RR-75-1A, Asphalt Hot Mix Emission Study;
RR-80-1, Exposure of Paving Workers to Asphalt Emissions;
IS-173, Energy Requirements for Roadway Pavements

and of the National Asphalt Paving Association
SR-166, Evaluation of Stack Emissions from HMA Facility Operations;
IS-123, PS-23, Special Report #134, Study of Paving Asphalt Fumes; and, 
press release ; "Asphalt Pavement is the surprise leader in recycling---"

Heavy loads starting and stopping at signalized intersections place a very high stress on the pavement compared to the same loads that are constantly moving. In these areas special hot mix asphalt (HMA) mixtures are required to provide high stability that will resist these high stresses. Correcting this condition requires removing all the unstable material down to a layer that is not deforming and replacing it with a high stress mixture. There are many HMA mixes that can used for this purpose. Which is most appropriate depends largely on the quantity of material to be produced. For more information on high stress treatments see our "Standard Practice for the Treatment of High Stress Locations Using Hot Mix Asphalt" or High Stress Pavement Demonstrated in Fostoria, Ohio.

Regular preventive maintenance (PM) is essential to achieving the design life of your hot mix asphalt (HMA) pavements. Experience has shown that a thin HMA overlay is among the most cost effective PM surface treatments available, combining high levels of service with long life and modest cost. There are many HMA mixes that can be used for a PM overlay, depending upon the conditions. In every case what is needed is a surface course of uniform thickness that can be laid and compacted to maximum density so as to provide an impervious surface over the pavement structure. For more information on HMA overlays for PM treatments see our Standard Practice for the Use of Hot Mix Asphalt Overlays in Preventive Maintenance Activities. and our technical documents on "Smoothseal"

Actually, just a catchy name invented by some TV reporter for nighttime resurfacing. Because of concerns for customer delay, more and more agencies are specifying that paving be done during off-peak traffic hours. With cold milling and HMA resurfacing work can be done at night or at other times when traffic inconvenience can be minimized.

Studies have shown that a smooth ride is the number one concern of road users. Furthermore, another study has shown that initial smoothness improves the performance and lowers the maintenance cost of a pavement over its life cycle. HMA pavements start out smoother and stay smoother throughout their lives, making them the best choice for new construction. For more information on pavement smoothness, see our series of articles on "Pavement Smoothness".

"Perpetual Pavement" is the name coined to describe a three-layer, flexible pavement design and construction concept. Application of the concept produces a deep-strength asphalt pavement that can resist structural fatigue distress for a long time (at least 50 years) and, thus, results in a long-lived pavement.& These long-lasting structural bases can be economically maintained by replacing just the surface, never needing total removal and replacement.

For more information on the "Perpetual Pavement" concept, see the Perpetual Pavement section on Asphalt Pavement Alliance.

"Smoothseal" is the industry name for ODOT Specification Item 424, Fine Graded Polymer Modified Asphalt Concrete, type A or B (2005 CMS). These materials blend high-quality aggregates with polymer modified asphalt to produce one of the most durable, dense-graded paving mixtures available. These materials are especially well suited for thin, maintenance overlays.

For more information on "Smoothseal", see the "Smoothseal" page.

Flexible Pavements of Ohio has advertising opportunities in "Ohio Asphalt", the association's quarterly magazine, our annual membership directory and on the website:

For advertising information, contact Flexible Pavements of Ohio at or call, toll-free, 888-446-8649.

The Ohio Center for Asphalt Pavement Education (OCAPE) is a unit of Flexible Pavements of Ohio for carrying out the educational mission of the association. The goal of OCAPE is provide educational opportunities and recognition to member companies' personnel and to specifiers and customers of the Hot Mix Asphalt industry. 

For more information, visit the OCAPE programs.

Flexible Pavements of Ohio (FPO) encourages association membership on the part of both private companies and public agencies, which support the common goal of improving the quality of asphalt pavements constructed in Ohio. FPO has categories of membership for bituminous concrete producers, contractors, aggregate producers, equipment manufacturers and distributors, asphalt marketers, general membership, architects and highway consulting engineers and political subdivisions. Brochures are available that further describe the benefits of association membership.

For more information, visit our Join FPO page.

Highway noise is becoming a social issue with which transportation departments have to deal. Most state DOT's will build noise walls under certain circumstances in accord with federal regulations. However, in recent cases in Michigan, Pennsylvania and Arizona affected residents have demanded a change in pavement surface from concrete to quieter asphalt. The United Kingdom purposely surfaces its freeways with asphalt to reduce noise.

Many studies over the years have shown that sound produced at the tire-pavement interface with asphalt pavements lacks the level of annoying frequencies commonly generated from concrete pavement surfaces. Special asphalt surfaces, such as open-graded friction course (OGFC) and stone matrix asphalt (SMA) reduce highway noise at the source even further.

Visit the interactive pavement noise website at

For more information on the issue of reducing tire/pavement noise, see the following references:

  1. article by Wayne Jones, PE, "Highway Noise Control With HMA", printed in Asphalt Magazine, Fall 2002 This article is available on line at
  2. article by P.S. Kandahl, PE, "Asphalt Pavements Mitigate Tire/Pavement Noise", printed in Hot Mix Asphalt Technology Magazine, March/April 2004
  3. NCHRP Synthesis of Highway Practice 268, "Relationship between Pavement Surface Texture and Highway Traffic Noise", R. Wayson, et al, 1998, published by the Transportation Research Board of the National Research Council and available for purchase at
  4. Final Report, "Effects of Pavement Type on Traffic Noise Levels", March 2000, Herman and Ambroziak, Ohio University, Ohio Research Institute for Transportation and the Environment,
  5. Purdue University, Institute for Safe, Quiet and Durable Highways,
  6. Asphalt Alliance website,

Rubblization is a cost-effective means of rehabilitating deteriorated portland cement concrete (PCC) pavements and is one of a series of "fractured slab" techniques that also includes "break and seat" and "crack and seat". In Rubblization the existing concrete pavement is broken into an aggregate base, and then it is overlaid with a designed thickness of asphalt concrete. These pavement rehabilitations are commonly designed to equal or exceed the design parameters for new pavements. This technique minimizes delays and allows for construction during off-peak hours. The rubblized roadbed is left in place and used as part of the new pavement structure. This not only saves landfill space and the costly construction necessary to dispose of wasted material, but uses the material for a beneficial and cost saving purpose.

For more information on Rubblization, view the article Arkansas' Interstate Rehabilitation Program.

And the see the articles in the "Ohio Hot-Mix Asphalt Current News":  "I-77 Rubblization", Vol 11 No. 2, June 2002; "Medina 271 Completed", Vol 11 no. 1, Mar 2002 and "City of Blue Ash Tries Rubblization", Vol 10 No. 3, Sept. 2001.  These articles can be found in the Newsletter Archives.

It’s reclaimed asphalt pavement (RAP). In Ohio the asphalt industry recycles millions of tons of RAP into new asphalt pavement every year, the largest tonnage of any industry. And, asphalt's 80% recycling rate is higher than for any other material. Because this recycling is beneficial and economical, it happens without government mandates or subsidies.

For more information on recycling, see the Flexible Pavements of Ohio statement on recycling, view the NCAT brochure, Reclaimed Asphalt Pavement FAQs, view the NAPA brochure "Take the RAP" and view the article from the Fall Issue of Ohio Asphalt on "The Case for Using Reclaimed Asphalt Pavement

For more suggestions on ways to save money in your paving program, read the NAPA Special Report 191.

Porous asphalt pavements are being used to reduce or eliminate storm water runoff from parking lots and other facilities.  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.  These designs can reduce pollution and replace expensive detention and treatment facilities.  Porous Pavement systems are rapidly gaining favor with designers and regulators as an economical approach to storm water management for sustainable or low-impact development. As the NPDES permit requirements have become more widely applicable, it has become necessary that developers find more innovative means of compliance.   Porous pavement systems are commonly being used as part of a strategy to obtain Leadership for Energy and Environmental Design (LEED) certification for green building projects.

A porous asphalt pavement design manual, IS-131, is available from the National Asphalt Pavement Association (NAPA)  at

While there you'll want to view the information in the porous pavement on-line library

Additional resources on porous pavement in stormwater management are available at

Another excellent article, " Porous Asphalt Pavement with Recharge Beds" is available at

Sample specifications for the asphalt materials for the porous pavement surface and base courses follow: 
Porous Asphalt Pavement Surface Course (Rev. 12September2012)
Porous Asphalt Pavement Base Course 
FHWA Technical Advisory, Open Graded Friction Courses (T 5040.31) (Dec. 26, 1990)

Other information is available at the "International Stormwater Best Management Practices Database"

For more information and articles view the following PDFs:
Asphalt-the Right Choice for Porous Pavements
Lenexa, Kansas Tries Porous Asphalt on for Size
Thinking Green with Porous Asphalt
NAPA Porous Pavement Presentation Slides

Warm Mix Asphalt (WMA) is a term being used to describe several different technologies that are being used to produce hot-mix asphalt (HMA) paving mixtures at significantly lower mixture and placement temperatures. Potential advantages of these technologies include: lower energy consumption; lower fumes, odors and emissions; easier placement and less aging of the binder from exposure to heat. For a complete description of this developing technology visit or the FHWA site

You will also be interested in the discussions of Warm Mix Asphalt in the Spring, 2006 issue of Ohio Asphalt magazine and you will want to view the presentations presented at the Ohio "Warm Mix Asphalt Technologies Field Trial/Open House, September 12, 2006.