Title: Safety Risks Associated with Carbon Nanotube- Reinforced Mortar

Author(s): Hugh D. Miller, Sara Mesgari, Ali Akbarnezhad, and Stephen Foster

Publication: Materials Journal

Volume: 114

Issue: 6

Appears on pages(s): 897-909

Keywords: carbon nanotubes; fiber reinforcement; mortar

DOI: 10.14359/51700892

Date: 11/1/2017

Abstract:
Carbon nanotube (CNT) reinforcement has been reported to improve mechanical properties and durability of concrete. However, numerous health concerns have been attributed to CNTs, forming a major barrier to their widespread use. Human exposure to CNTs is considered unlikely while CNTs are dispersed in liquid or embedded in a concrete matrix. However, respirable CNT-contaminated particles, including free CNTs and CNTs attached to hydrated cement products, may be released during production, processing, or demolition of CNT-reinforced concrete. In this paper, the risk of presence of respirable CNT-contaminated particles in the wastewater generated during mixing and dusts generated during crushing of CNT-reinforced mortar is investigated by varying the type (singlewalled and multi-walled CNTs), concentration, and dispersion method of CNTs. A considerably lower risk of presence of CNTs in respirable particles generated during mortar production and demolition is found for multi-walled CNTs versus single-walled CNTs. Furthermore, functionalization of CNTs is identified as an effective method to reduce the health and safety risks associated with mixing and demolition of the CNT-reinforced cementitious materials. The presence of CNTs in the respirable particles generated is found to increase with an increase in concentration of CNTs.