Strain sensitivity of steel-fiber-reinforced industrial smart concrete

Abstract

Self-sensing cementitious composites can enable structures that are capable of carrying the loads applied on them while monitoring their condition. Most of earlier research has focused on the incorporation of nanofillers or microfibers into cement paste or mortar composites. However, there have been very limited number of studies on the development of steel-fiber-reinforced cementitious composites with self-sensing capabilities. This study explores strain sensitivity of concrete mixtures that include coarse aggregates up to 15 mm diameter and steel fibers with a length of 13 mm and a diameter of 0.25 mm. Five different concrete mixtures with steel fibers at 0%, 0.2%, 0.35%, 0.5%, and 0.8% volume ratios were fabricated. Compression tests with simultaneous measurement of strain and electrical resistance were conducted on the cubic specimens. Gauge factor and percent linearity that is a measure of error in strain sensing were calculated. Concrete mixtures with 0.5% steel fibers possess a strong linear relationship between applied strain and electrical resistance change with a gauge factor over 20 times larger than that of traditional metal strain gauges. Phenomenological models for different resistivity and gauge factors of cement paste/mortar with respect to concrete with large aggregates and short–long fiber cement composites were presented.

Effects of Steelmaking Slag and Moisture on Electrical Properties of Concrete

“…In a different study, Monteiro et al [10] suggested that the optimal amount of carbon black to improve both mechanical and electrical properties of concrete containing is 7%. Together, these studies demonstrate that the incorporation of conductive materials into concrete may enable structural health monitoring (SHM) and vehicle detection of civil infrastructure [1,3,11].…”

“…As concrete technology improves, concrete structures are lasting longer and are subject to material deterioration and changing environments, including climate [1][2][3]. Environmental and structural stressors shorten the life of concrete.…”

“…Environmental and structural stressors shorten the life of concrete. Therefore, there is an increasing interest in the development of efficient, economic, and accurate methods to assess the structural health of concrete structures [1,4]. Conventional and commercial strain sensors for infrastructure can only assess the local behavior of structures, and they are limited in use due to poor durability, low sensitivity, and low gauge factors [1,[4][5][6][7].…”

“…Therefore, there is an increasing interest in the development of efficient, economic, and accurate methods to assess the structural health of concrete structures [1,4]. Conventional and commercial strain sensors for infrastructure can only assess the local behavior of structures, and they are limited in use due to poor durability, low sensitivity, and low gauge factors [1,[4][5][6][7]. To address the need for accurate and practical concrete monitoring methods, researchers have proposed "smart concrete structures" that measure load/deformation and stress/strain by incorporating conductive materials [2][3][4].…”

Developments and Applications of Carbon Nanotube Reinforced Cement-Based Composites as Functional Building Materials

“…The self-sensing ability of concrete is achieved by a change in the conductive network of the conductive material inside the concrete (Al-Dahawi et al, 2016a;Al-Dahawi et al, 2016b;Al-Dahawi et al, 2017;Yıldırım et al, 2018;Demircilioğlu et al, 2019;Yıldırım et al, 2020). Smart concrete is developed by adding carbon nanotube (Xing et al, 2016;Al-Dahawi et al, 2017;Gupta et al, 2017;Yoo et al, 2017;Yıldırım et al, 2018;Lee et al, 2020;Yıldırım et al, 2020), carbon fibers (Al-Dahawi et al, 2017;Yıldırım et al, 2018;Yıldırım et al, 2020), steel fibers (Le and Kim, 2017;Demircilioglu et al, 2020;Le and Kim, 2020), graphite nanofibers (Yoo et al, 2017), graphene (Al-Dahawi et al, 2016a;Al-Dahawi et al, 2016b;Al-Dahawi et al, 2017;Yoo et al, 2017;Birgin et al, 2020;Wang et al, 2020), nickel or hybrid materials (Azhari and Banthia, 2012;Konsta-Gdoutos and Aza, 2014) and other functional fillers. The research on CNT reinforced self-sensing cement-based materials is the most concentrated.…”