111 Toxicity Assessment of a Carbon Nanotube Embedded Concrete

Abstract Carbon nanotube (CNT) as a reinforcement enhances durability and performance of concrete composites. Exposure to some forms of CNT is known to cause adverse pathological outcomes. To understand potential toxicity arising from use of CNT-enabled concrete composites as it goes through various occupational life cycle stages, we evaluated 1) the physicochemical characteristics and toxicity of the as-produced CNT and 2) how particulate release during concrete manipulation (e.g., cutting) is altered by CNT incorporation. Physical dimensional profiling indicated a geometric mean length of 0.72 µm and 32 nm in diameter. The toxicity of the as-produced CNT was similar to an agglomerated CNT studied in our previous research, lacking the more severe toxicity associated with longer length and diameter CNT. Four concrete test samples, three different formulations with CNT and one without, were cut in a specialized chamber to simulate an occupational scenario. The mass median aerodynamic diameters from varying CNT incorporated composites did not change and was 5.23 µm in diameter. No free CNT was captured in the aerosols or was visible on the surface of the concrete. The toxicity of the released particulate is currently being investigate using in vitro screening tests designed to investigate mechanisms of potential toxicity. There were minimal changes in the particulate size distribution profiles after cutting, suggesting adding CNT to concrete may have subtle effects on the toxicity of the generated particulate.