This project was funded by the National Institute for Transportation and Communities (NITC), grant number 1075.
Concrete construction, Sustainable construction, Concrete -- Environmental aspects, Concrete -- Additives
Natural pozzolans can be a replacement for portland cement in many applications. Some natural pozzolans are byproducts of industrial processes. Other natural pozzolans, such as volcanic ash, occur naturally. This study determined the suitability of Mt. Mazama volcanic ash as a natural pozzolan and explored innovative uses of the material for roadway improvement. Requirements of natural pozzolans are specified in ASTM C618 – coal fly ash and raw or calcined natural pozzolan for use in concrete. This study concluded that volcanic ash from Mt. Mazama meets chemical requirements of a natural pozzolan. In its unprocessed, natural form, Mt. Mazama volcanic ash does not meet fineness, moisture or strength requirements as a natural pozzolan. An innovative study of the strength of mortar cubes created with increasing replacement of portland cement with Mt. Mazama volcanic ash showed that decreases in strength occur with increased percentage replacements. When the Mt. Mazama volcanic ash is crushed and passed through a No. 200 sieve, this decrease in strength is less than unprocessed material. Slurry mixes of Mt. Mazama volcanic ash, lime and portland cement applied to gravel materials bound material to a greater percentage, and reduced potentially airborne particulates to a greater degree than using portland cement slurry alone. A sustainability analysis concluded that any replacement of portland cement with volcanic ash reduces embodied energy and carbon dioxide emissions.
Sleep, Matthew and Masley, Morgan. The use of Mt. Mazama volcanic ash as natural pozzolans for sustainable soil and unpaved road improvement. NITC-RR-1075. Portland, OR: Transportation Research and Education Center (TREC), 2018.