The Use of Mt. Mazama Volcanic Ash as Natural Pozzolans for Sustainable Soil and Unpaved Road Improvement

Matthew Sleep, Oregon Institute of Technology


The Klamath Basin, located in Southern Oregon, is a small, rural community with significant agricultural and timber resources.  The formation of this community in the early part of the 20th century began with ‘reclaiming’ wetlands for agricultural use.  A series of canals, levees, dams and pumping stations were constructed to irrigate reclaimed wetland areas.  

Recently the Bureau of Reclamation has reclaimed some of these former wetland areas back to wetlands.  These wetlands serve as wildlife refuges and natural areas for the community of Klamath Basin.  These wetlands are accessed along roads atop levees that are constructed of soft, compressible soils.  A graduate student studied one of these access roads and found that several areas had settled significantly and were in need of repair.  To repair these access roads, soil improvement was suggested.  

Conventional methods of soil improvement include compaction, excavation and replacement and mixing the soils in place with either powdered portland cement or lime.  Powdered portland cement and lime are both expensive materials, and require significant amounts of energy to produce.  In addition the environmental effects of adding these materials to an ecologically sensitive site like the Wood River Wetland are unknown.
For these reasons we investigated alternative materials to be mixed with the soils to improve their properties for access roads.  Through research, we found that the eruption of Mt. Mazama approximately 7,000 years ago blanketed the Klamath Basin region with a thick layer of volcanic ash that is known to behave similarly to portland cement.  These deposits have been previously mapped for their economic value.  Using these materials in place of portland cement for soil stabilization of access roadways has three distinct benefits:

1.	They do not introduce materials to the environment that are not already present.
2.	They require only transportation to be produced, thus they have a significantly smaller carbon footprint than portland cement which consumes energy to manufacture.
3.	If found to be beneficial, they would create a new, relatively untapped economic product found in the Klamath Basin.

Preliminary research conducted by students show that these materials do have some beneficial properties but more research is necessary.  
In addition to soil stabilization for access roadways, there is the potential to use these materials to reduce the dust produced from gravel roadways.  The Environmental Protection Agency (EPA) has listed particulate pollution (PM) as one of the six principle air pollutants.  A 2005 study by the EPA showed that 33% of this pollutant comes from the dust of unpaved roads.  Dust produced by gravel roadways has been linked to asthma, emphysema, heart disease, and chronic bronchitis among others (  It is anticipated that cementitious reaction of these natural pozzolans may reduce road dust and particulate pollution from gravel roads.  

It is anticipated that with the data collected from this preliminary research, further efforts can be made regarding dust abatement and roadway improvement using natural pozzolans from Mt. Mazama.


It is anticipated that these materials may help improve sustainability of unpaved roads by providing stabilization and reduction of airborne particulates.  Using locally sourced materials will further increase sustainability efforts. 

September 2017- We have been able to stabilize compacted aggregates with a slurry of volcanic ash, portland cement and lime.  This may aid in dust abatement.  We have also created stabilized soils with volcanic ash and lime.   

Project Details

Project Type:
Small Starts
Project Status:
End Date:
April 30,2018
UTC Grant Cycle:
Natl Small Starts Round 3
UTC Funding: