Iceland Engineers Confirm Volcanic Ash's Binding, Aar-Quelling Properties
- Written by Concrete News
Reykjavik-based International Centre of Research and Applied Technology for Alkali Aggregate Reactions has observed through mortar specimens AAR-mitigating potential in ash from April's Eyjafjallajàkull volcano eruption, crediting the material's particle fineness and approximately 60 percent silicon dioxide content.
Using methods from ASTM C 1260 Multi-Laboratory Study of the Accelerated Mortar Bar Test for Alkali-Silica Reaction, staff at the Mannvit Engineering-housed facility prepared specimens from control (100 percent portland cement) and ash (5 percent portland cement substitution) mixes. After the bars' 14-day exposure in a NaOH solution, Centre founder Dr. BØrge Johannes Wigum observed dramatically lower AAR expansion in the ash (0.02 percent) versus the control (0.45 percent) specimens.
According to Mannvit Concrete Scientist Karsten Iversen, the volcanic ash's chemical composition is similar to fly ash. He and colleagues also examined particle-size distribution of portland cement, fly ash and Eyjafjallajàkull ash, plus the latter material's effect on fresh and hardened mortar properties. Tests indicate the volcanic ash, if feasible to quarry, could have potential as a concrete additive.
While mining has not been formally evaluated, Dr. Wigum notes that thick layers of ash at the Eyjafjallajàkull mountain have been recorded. Additional deposits blended with vegetation in the farmland below have been cited as the main sources for dust storms; their tendency to classify the material and form dunes might lead to commercial-scale quarrying.
Dr. Wigum also notes that the new ash would join domestically produced fine and coarse aggregate, all of volcanic origin, plus some granite imported from Norway. Rhyolite has likewise been used in Iceland as a supplementary cementitious material and cement mill feed.