Effect of multiwalled carbon nanotubes on compressive behavior of concrete at elevated temperature for mass concreting

In this article, CNTs have been used in concrete, and the resulting properties are evaluated. Also, the CNT-reinforced concrete was exposed to elevated temperature, and the corresponding change in mechanical performance was investigated. Mechanical properties were studied, such as compressive and flexural strengths, stress-strain response, elastic modulus, compressive toughness, mass loss, and deterioration caused by exposure to elevated temperatures. Concrete specimens were heated to 200, 400, 600, and 800 °C at a heating rate of 5 °C/min and then tested for residual properties. CNT-reinforced concrete showed a higher compressive strength, elastic modulus, flexural strength, and compressive toughness than the control specimens. 0.15-CNT reinforced samples showed an increase of nearly 33% in Compressive strength and 50% in flexural strength. From the visual inspection, CNT-reinforced specimens showed less cracking at higher temperatures. Moreover, the effect of plastering concrete with CNTs was studied, which depicted better strength retention on exposure to fire. At 600 °C, 0.3 P-CNT plaster samples retained up to 43% of compressive strength and 46% of flexural strength, whereas control samples only retained up to 29% and 34% of their original strengths, respectively. Thus, it can be concluded that CNTs utilization in concrete is efficient for improved concrete fire resistance.