Dr. Abdel Bachri, Dr. Md Islam, and Dr. Lionel Hewavitharana of Southern Arkansas University will use the ArDOT grant to research the use of wood ash as a filler in asphalt.
The Arkansas Department of Transportation is paying Southern Arkansas University in Magnolia to test if wood can be used in asphalt production.
The state Legislature approved Act 705 in 2017 authorizing the Transportation-Related Research Grant Program. Md Rashedul Islam, a professor of engineering at SAU, applied for a grant through the program to fund research into using wood ash as a filler in asphalt.
ArDOT awarded the $291,650 grant in February. Islam will lead the study along with Dean Abdel Bachri of the Department of Science & Engineering.
“It was amazing,” Islam said. “It is the largest grant we have received in recent time.”
SAU is in a prime location to do the research. Everyone should be aware of the amount of timber grown in southern Arkansas, and there is a wood incinerator in Columbia County not far from the SAU campus.
The university said in its application that the incinerator generates 144 cubic feet of wood ash every week, so there would be a convenient supply of raw material.
Bachri said other materials such as lime, stone dust and rice have been used as filler for hot mix asphalt, but not much attention has been paid to wood ash.
“It is very interesting,” Bachri said. “We were surprised that people have considered different types of filler for asphalt mixes. Nobody had really used wood ash and there isn’t a whole lot of information about it out there. You always use some kind of filler.”
A majority of the grant will go toward buying equipment for the research. The wood ash will be analyzed so all the properties can be registered for each batch of filler — different trees from different counties can have different properties depending on chemicals in the environment and soil and atmosphere.
Bachri said wood ash can contain trace amounts of iron, calcium and potassium.
“We have done some preliminary studies to examine the samples to understand what they really have,” Bachri said. “The presence of these minerals actually reinforces that what we want to use it for is very viable.”
Islam said using wood ash could save costs on producing asphalt. Fillers such as lime are more expensive, and wood ash is a byproduct of timber production.
Wood ash had been used in the past as boiler fuel for companies to create steam. The low cost and easy availability of natural gas has made wood ash as fuel unnecessary.
The researchers said wood ash’s only use now is as a packed paving material for county roads. Using it as a filler could keep it from causing pollution, Islam said.
“We are expecting to get better quality product using this kind of filler material,” Islam said. “The way it will help is when you are including the ash. We are utilizing that instead of just throwing it away.”
It’s a cheap bet for the Department of Transportation, which spends millions a year on road maintenance. Anything that can shave off a few bucks here and there on the cost of asphalt has to be tempting.
Using wood ash also feeds into the growing sustainability movement. If timber is going to be used more now in construction — the cross-laminated timber trend got a boost when Walmart Inc. said it would use the material for its new home office in Bentonville — then reducing the waste of timber production is an admirable goal, especially if it could also be a profitable business.
“It works perfectly with the sustainable construction practice,” Bachri said. “The global sustainability agenda and the use of secondary material is growing.
“If you look at the trees, Arkansas has a lot of forestry available. That will generate a lot of wood waste. It is a very promising idea and plays very well with renewable energy and sustainability.”
SAU’s Natural Resource Research Center is on site to analyze the filler composition, and Bachri said he hopes the program will be “up and running” by the fall of 2020. The grant pays for two years of research.
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