Experimental investigations on the mechanical properties and damage detection of carbon nanotubes modified crumb rubber concrete

This study presents a modified crumb rubber (MCR) concrete design mix reinforced with multiwalled carbon nanotubes (MWCNTs), mechanical characterization, and cracking monitoring using the acoustic emission (AE) technique. The results showed that the bridging effect of MWCNTs and MCR in the concrete mix mitigated the shortcomings of MWCNT-MCR concrete and improved the flexural and compressive strengths by 18.3% and 26.5%, respectively, at 28 days. The stress-strain behavior of the MWCNT-MCR concrete showed improved ductility (48.12%), axial strain (50.12%), and toughness (27.15%) compared to the reference specimens. The MWCNT-MCR concrete exhibited a mechanical response in three distinct loading phases. Overall, tensile failure (>4000 mu s/v and >35 kHz) was observed in the tested specimens through the RA value (ratio of rise time to amplitude of AE waves) and average frequency (AF) distribution. Based on the amplitude distribution of the AE waves, the damping capacity of the MWCNT-MCR concrete was improved by 27.83%, and the fracture mechanism between micro and macro cracks was identified through a b-value approach. Finally, a regression model was established to predict the Ec of MWCNT-MCR concrete and the two-way interaction effect on the mechanical properties of the developed mix design.

Automated summary

This study presents the mechanical characterization and cracking monitoring of a modified crumb rubber (MCR) concrete design mix reinforced with multiwalled carbon nanotubes (MWCNTs) using the acoustic emission (AE) technique. The results showed that the bridging effect of MWCNTs and MCR in the concrete mix improved the flexural and compressive strengths by 18.3% and 26.5%, respectively. The MWCNT-MCR concrete exhibited improved ductility, axial strain, and toughness compared to the reference specimens.