title: A mechanism for the production of ultrafine particles from concrete fracture.
abstract: While the crushing of concrete gives rise to large quantities of coarse dust, it is not widely recognized that this process also emits significant quantities of ultrafine particles. These particles impact not just the environments within construction activities but those in entire urban areas. The origin of these ultrafine particles is uncertain, as existing theories do not support their production by mechanical processes. We propose a hypothesis for this observation based on the volatilisation of materials at the concrete fracture interface. The results from this study confirm that mechanical methods can produce ultrafine particles (UFP) from concrete, and that the particles are volatile. The ultrafine mode was only observed during concrete fracture, producing particle size distributions with average count median diameters of 27, 39 and 49 nm for the three tested concrete samples. Further volatility measurements found that the particles were highly volatile, showing between 60 and 95% reduction in the volume fraction remaining by 125 °C. An analysis of the volatile fraction remaining found that different volatile material is responsible for the production of particles between the samples.
authors.affiliation: International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Australia.
authors.forename: Nassib
authors.initials: N
authors.lastname: Jabbour
authors.affiliation: International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Australia.
authors.forename: E
authors.initials: E
authors.lastname: Rohan Jayaratne
authors.affiliation: International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Australia.
authors.forename: Graham R
authors.initials: GR
authors.lastname: Johnson
authors.affiliation: International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Australia.
authors.forename: Joel
authors.initials: J
authors.lastname: Alroe
authors.affiliation: Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, 38108 Braunschweig, Germany.
authors.forename: Erik
authors.initials: E
authors.lastname: Uhde
authors.affiliation: Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, 38108 Braunschweig, Germany.
authors.forename: Tunga
authors.initials: T
authors.lastname: Salthammer
authors.affiliation: International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Australia.
authors.forename: Luke
authors.initials: L
authors.lastname: Cravigan
authors.affiliation: International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Australia.
authors.forename: Ehsan Majd
authors.initials: EM
authors.lastname: Faghihi
authors.affiliation: Department of Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, United Kingdom; Environmental Flow (EnFlo) Research Centre, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, United Kingdom.
authors.forename: Prashant
authors.initials: P
authors.lastname: Kumar
authors.affiliation: International Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Australia. Electronic address: l.morawska@qut.edu.au.
authors.forename: Lidia
authors.initials: L
authors.lastname: Morawska
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D003252:Construction Materials / Q000032:analysis*; D004391:Dust / Q000032:analysis; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D014835:Volatilization
chemical_list: D000393:Air Pollutants; D004391:Dust; D052638:Particulate Matter
keywords: Airborne dust; Concrete; Secondary particles; Ultrafine particles; Urban pollution