Carbon Black Engineered Cementitious Composites - Mechanical and Electrical Characterization

Synopsis: The protection and health monitoring of deteriorating concrete infrastructure requires a new generation of self-sensing structural materials that possess intrinsic damage tolerance but offer self-sensing capabilities that are tailored to diagnose states of cracking. Engineered Cementitious Composites (ECC) doped with carbon black (CB) nano-particles are proposed as highly damage-tolerant materials whose electrical properties can be correlated to strain and cracking. This study investigated the effect of CB dosage on the CB-ECC rheological, mechanical and electrical properties. By incorporating CB nano-particles into the ECC system while simultaneously controlling the rheological properties of the fresh mix, the fully cured CB-ECC elements achieved close-to-uniform PVA fiber and carbon black dispersion, reduced bulk resistivity by an order of magnitude, strain hardening behavior with tensile strain capacity of 0.26 to 1.38%, and reduced crack widths of 30 to 40 m during tensile loading. Furthermore, all of the CB-ECC specimens exhibited prominent piezoresistive behavior with resistivity increasing in tandem with applied tensile strain, thereby indicating the potential of CB-ECC for strain and damage sensing.