Structural Design Guide for Porous Asphalt
Commonly used for parking lots and other light-duty applications, full-depth porous asphalt pavements are increasingly being used on roadways as part of efforts to mitigate flooding hazards, reduce hardscape, and improve sustainability. To help ensure these new porous asphalt roadways provide reliable performance under traffic, NAPA has published Structural Design Guidelines for Porous Asphalt Pavements.
Written by Charles W. Schwartz, Ph.D., and Kevin D. Hall, Ph.D., P.E., with the support of the NAPA–SAPA Pavement Economics Committee's Pavement Design Task Group, Structural Design Guidelines for Porous Asphalt Pavements discusses the structural design procedure for porous asphalt and the required inputs using the AASHTO 93 design method.
The Most Commonly Recycled Material? Asphalt
The latest NAPA/FHWA survey of asphalt producers' use of recycled materials and warm-mix asphalt finds that more than 78 million tons of recycled materials — mostly reclaimed asphalt pavement and recycled asphalt roofing shingles — were put to use in new asphalt pavements during 2017. The same survey found that nearly 39 percent of all asphalt pavement mixture produced during the 2017 construction season was produced using energy-saving warm-mix asphalt technologies.
The survey, conducted by NAPA in partnership with FHWA for each construction season since 2009, found that more than 147 million tons of WMA was produced in 2017. In 16 states, more than half of all asphalt pavement mixture was produced as WMA; in eight of those states, more than 75 percent of asphalt pavement mixture was produced using WMA technologies.
The survey also found that more than 76.2 million tons of reclaimed asphalt pavement (RAP) and nearly 950,000 tons of recycled asphalt roofing shingles (RAS) were used in new asphalt pavement mixes in the United States during in 2017. Reclaiming and reusing the asphalt cement in RAP and RAS saved more than $2.2 billion in 2016 compared to the use of virgin materials and saved nearly 50 million cubic yards of landfill space from reclaiming RAP alone.
A full copy of the survey, including appendixes with state-by-state data, can be downloaded from www.AsphaltPavement.org/recycling.
Silica Rule Support for Asphalt Industry
With enforcement of OSHA's new silica rule beginning in September 2017, companies engaged in roadway construction must be aware of the potential for exposure to silica associated with common roadway construction activities, mitigation strategies and technologies, and reporting, monitoring, and other regulatory obligations.
NAPA has developed a series of reports and guidance to aid in designating a competent person in line with the silica rule, developing written silica exposure control plans, and the Table 1 engineering controls compliance options for roadway milling operations. These and other resources are all available through NAPA's Silica Rule webpage. NAPA will continue to update the site with links to tools and resources as they are developed.