Could Icelandic ash cloud have a silver lining?
THE Eyjafjallajökull volcano in Iceland, which started erupting on 14 April 2010, is best known for paralyzing international air traffic. However, concrete specialists at Iceland’s
Mannvit Engineering say that the transportation of the ash over such long distances might also serve as an indicator of properties useful to the concrete industry.
In 2009, Mannvit Engineering created an International Centre of Research and Applied Technology for Alkali Aggregate Reactions (AAR) – the undesirable chemical reactions that can cause structural problems in concrete if not mitigated effectively.
Researchers at the Centre have identified the volcanic ash as potentially useful for mitigating AAR due to the fineness of the particles and the high content of SiO2 (approximately 60%). To test the value of the ash, engineers have established accelerated tests to measure the properties of the material and its usefulness in mitigating AAR.
‘The accelerated mortar bar test provides a relatively good indication of the mitigating effects of various pozzolans and other supplementary cementitious materials,’ explained the founder of the Centre, Børge Johannes Wigum. ‘In the test, mortar samples were made both without ash and with 5% replacement of the cement. After 14 days of exposure in a 1N NaOH solution at 80°C, expansion measurements of the mortar bars indicate that the ash dramatically reduces expansion due to AAR.’
According to Mannvit Engineering’s concrete scientist, Karsten Iversen, the chemical composition of the volcanic ash is similar to fly ash, a well known concrete additive derived from the burning of coal.
Other aspects of the Eyjafjallajökull ash were also examined at Mannvit’s material testing laboratory, including grain size distribution and properties of fresh and hardened mortar. Test results indicate that the volcanic ash – if feasible to quarry – may prove an attractive potential additive for use in the Icelandic concrete industry.