Study on self-monitoring of multiple cracked concrete beams with multiphase conductive materials subjected to bending

Abstract

The multiphasic conductive admixtures like macro steel fiber (SF), nano carbon black (NCB) and carbon fiber (CF) are incorporated into concrete to improve the conductivity and mechanical properties. In this study, the mechanical and conductive properties of the concrete beam are explored by the hybrid use of different conductive admixtures. The deflection hardening (multiple cracking) behavior of concrete beam with different fiber content, monitoring of single and multiple cracks of diphasic (SF+NCB) and triphasic (SF+CF+NCB) conductive concrete beam through resistance measurement is investigated. Moreover, the relationship between fractional change in resistance (FCR) and crack opening displacement is established to study the influence of different types and amounts of electric conductive admixtures on self-sensing behavior of concrete beam. Results reveal that the deflection hardening (multiple cracking) behavior is obtained with 70 kg m−3 SF content. The single and multiple cracks monitoring is illustrated through load-time and FCR-time relationship. In addition, FCR improved linearly with an increment of NCB with triphasic conductive admixtures.