AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Aerosol Generation from Rapid Concrete Failure
Eric Heichelheim, Mija Hubler, LUPITA MONTOYA, University of Colorado Boulder
Abstract Number: 614 Working Group: Aerosol Exposure
Abstract When concrete structures are destroyed through extreme loading conditions, whether artificial or natural, a secondary risk to human health is imposed in addition of the immediate and primary risk of collapse. Suspended dust from failed concrete structures has been linked to negative health impacts, as was the case for first responders to the collapse of the World Trade Center in 2001.
This work investigated how modern concrete admixtures and inclusions can impact the mechanical properties of concrete under dynamic loading. In particular, it investigated the macro-, micro-, and nano- scale fragmentation of concrete and the associated aerosol generated as a function of different admixtures and inclusions. To study this effect, concrete columns were rapidly loaded in a 110-Kip MTS Universal Testing Machine until failure. Aerosol generated during the concrete failure was then sampled using TAS Minivol samplers (Airmetrics, Eugene, OR, USA, 5 L/min). Aerosol was then characterized for size, shape and toxicity.
Four concrete mixes were studied: regular concrete as a control case, fly ash and slag admixtures (to study effects of micro-scale inclusions), and steel-fiber reinforced concrete (to study effects of macro-scale inclusions). Previous studies have shown that concrete fragments follow the Rosin-Rammler distribution as predicted by brittle fracture probabilities. This work determined that such information is not representative of the aerosol particles that are generated, which are of primary importance for health. In particular, the inclusion of large fibers generated a higher concentration of nanoscale fragments. An improved analytical formulation for the probability of small fragment formation is being developed.