Behind the Screed

All roads open to WMA in NC

NCDOT has updated the WMA allowances to include any state route and interstates (when using PG76-22), for technologies that have been used in over 250,000 mix tons. Over the last 18 months, NCDOT has made a targeted effort to promote and track warm mix usage across the state. In doing so, they have also been able to monitor WMA performance. During this time period, Evotherm has been the most widely used warm mix product on the market. This represents a major shift for a state that was nearly 90% foam three years ago for any WMA that was produced.

Aside from the normal HMA mix design and JMF approval processes, there are no special requests needed for a contractor to utilize an approved WMA technology on major interstate projects. Evotherm is the only additive-based technology to achieve this threshold.

Author: David Newton

NAPA's 2011 RAP, RAS, & WMA Survey

NAPA, in partnership with the Federal Highway Administration (FHWA), is quantifying the use of RAP, RAS, and WMA through industry surveys. According to the latest data, during the 2011 construction season more than 66.7 million tons of RAP and 1.2 million tons of RAS were put to use in new pavements in the United States, saving taxpayers more than $2.2 billion. Also, about 19 percent of all asphalt produced in the country that year was made using warm-mix asphalt (WMA) technologies.

RAP: In 2011, RAP usage reached 66.7 million tons, a 7 percent increase from 2010 and a 19 percent increase from 2009. More than 99 percent of asphalt pavement reclaimed from roads was used in new pavements instead of going into landfills. In the survey, 98 percent of producers reported using RAP in their mixes for new construction, pavement preservation, rehabilitation, and other projects.

RAS: RAS usage also continued to climb, increasing to 1.2 million tons in 2011 — an 8 percent increase over 2010, and a 52.5 percent increase since 2009. Since 2009, RAS usage has been reported in 36 states. RAS includes both manufacturers’ scrap shingles and post-consumer roofing shingles.

WMA: In 2010, FHWA made warm-mix asphalt part of its Every Day Counts initiative to speed the deployment of technologies that can improve highway projects' quality, sustainability, and safety. In 2011, total WMA tonnage in the U.S. was estimated at about 69 million tons, a 67 percent increase from 2010 and a nearly 309 percent increase since 2009.  

Other tidbits from the survey:

• Table of estimated and reported plant mix asphalt tons by state
• Map of estimated average perentage of RAP by state
• Table of states reporting RAS use
• The SEAUPG states use the most WMA

Caltrans reduces GHG Emissions

This weeks CalAPA Asphalt Insider newsletter announces that "a new report released by Caltrans last week on the department's efforts to reduce Greenhouse Gas Emissions (GHG) has singled out innovative asphalt pavements as the department's No. 1 GHG-reducing pavement surface."

  

The report titled "Caltrans Activities to Address Climate  Change" pays special attention to innovative pavement designs, technologies and techniques including WMA and asphatl pavements that utilize rubber from discarded tires and Reclaimed Asphalt Pavement (RAP). Use of these technologies has:

• Reduced Caltrans' operational GHG emissions by more than 61,000 tons per year and equivalent to the annual emissions produced by approximately 11,800 passenger vehicles.
• Caltrans used 2.6 million tons of rubberized asphalt pavements which kept the equivalent of 6.7 million tires out of landfills.

 

Webinar series kickoff

As the "off-season" tradeshows begin to wind down, it's time for our webinar series to begin. Topics this year are: 

1. Removing fibers from mix designs
2. Achieving compaction with less effort
3. Ground tire rubber & WMA tips & tricks

Watch future posts for more details. Feel like something is missing? Drop a line to evotherm@mwv.com or comment below to let us know what you would like presented.

Author: Heather Dolan

Coldest of the Year?

The Coldest Paving of 2013 award may well go to McAsphalt Industries. In February, they tweeted "Paving in -2degC weather with warm mix #asphalt using @Evotherm on Herb Grey Parkway in Windsor ON" along with this picture:   

Brrrrrrrrrr! Did you pave any colder? Comment below for ultimate bragging rights.

Author: Heather Dolan

California sets WMA specifications

Caltrans recently published the latest warm mix asphalt update to their specifications. The Standard Specifications are revised to allow the Contractor to utilize WMA technologies in all projects. The Contractor can select a WMA technology from the approved list (which includes Evotherm) and must meet the material and placement requirements of HMA. Contractors in California no longer need special permission through a change order to use WMA. Highlights of the revised specification include:

• Defining WMA as asphalt produced at temperatures no greater than 275 F.
• Specifying procedures for evaluating the foaming characteristics of asphalt binders for use with mechanical foam technologies
• Requiring WMA technology representatives on-site only during the first 3 days of placement.
• Requiring Hamburg Wheel Rut Testing and T283 testing during the project.

The revisions can be found at http://www.dot.ca.gov/hq/esc/oe/standards.php under Revised Standard Specifications (RSS).

Author: Brandon Milar