PSI - Issue 67

ScienceDirect Structural Integrity Procedia 00 (2024) 000 – 000 Structural Integrity Procedia 00 (2024) 000 – 000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ

www.elsevier.com/locate/procedia

www.elsevier.com/locate/procedia

Procedia Structural Integrity 67 (2025) 8–16

International Symposium on Nanotechnology in Construction Materials NICOM8 Effect of temperature on the self-sensing behavior of carbon nanotubes/cement composites Oscar Aurelio Mendoza Reales a *, Thaís Carvalho dos Santos a , Maria Macedo Paiva a , Pedro de Almeida Carísio a , Adriana Paiva de Souza Martins a , Flavio Mamede Pereira Gomes b , and Romildo Dias Toledo Filho a a Universidade Federal do Rio de Janeiro, Ilha do Fundão Cidade Universitária, Rio de Janeiro 21941-909, Brazil. b FURNAS Centrais Elétricas S.A., BR 153 - km 1.290, Aparecida 74923-650, Brazil Abstract Concrete structures, such as pavement slabs, bridges, and dams, which are excellent candidates for the application of self-sensing composites, are usually exposed to a wide range of temperature variations. These variations can be originated from different sources such as heat release from cement hydration, day/night cycles, or seasonal weather changes. The implementation of most self sensing composites to monitor concrete structures is based on measurement of their electrical resistivity. It is known that the electrical resistivity of cement-based composites with carbon fibers is inversely proportional to temperature; nevertheless, there is little information available in the literature on how temperature variations affect the self-sensing capacity of carbon nanotube (CNT)/cement composites. This work studies how the electrical resistivity and piezo-resistive response of CNT/cement composites changes when temperature increases. First, the composites were heated from room temperature to 70 °C, allowing free deformation, to determine a relationship between temperature, thermal expansion, and electrical resistivity. Subsequently, piezo-resistivity experiments in steady temperature regime were performed at 25°C, 50°C and 70°C. It was found that if temperature is steady when deformation is imposed on a CNT/cement composite, the sensitivity and linearity of its electrical response are maintained. On the other hand, when temperature is in transient condition, CNT/cement composites work as a thermistor and such behavior must be considered when interpreting fractional resistivity change curves. International Symposium on Nanotechnology in Construction Materials NICOM8 Effect of temperature on the self-sensing behavior of carbon nanotubes/cement composites Oscar Aurelio Mendoza Reales a *, Thaís Carvalho dos Santos a , Maria Macedo Paiva a , Pedro de Almeida Carísio a , Adriana Paiva de Souza Martins a , Flavio Mamede Pereira Gomes b , and Romildo Dias Toledo Filho a a Universidade Federal do Rio de Janeiro, Ilha do Fundão Cidade Universitária, Rio de Janeiro 21941-909, Brazil. b FURNAS Centrais Elétricas S.A., BR 153 - km 1.290, Aparecida 74923-650, Brazil Abstract Concrete structures, such as pavement slabs, bridges, and dams, which are excellent candidates for the application of self-sensing composites, are usually exposed to a wide range of temperature variations. These variations can be originated from different sources such as heat release from cement hydration, day/night cycles, or seasonal weather changes. The implementation of most self sensing composites to monitor concrete structures is based on measurement of their electrical resistivity. It is known that the electrical resistivity of cement-based composites with carbon fibers is inversely proportional to temperature; nevertheless, there is little information available in the literature on how temperature variations affect the self-sensing capacity of carbon nanotube (CNT)/cement composites. This work studies how the electrical resistivity and piezo-resistive response of CNT/cement composites changes when temperature increases. First, the composites were heated from room temperature to 70 °C, allowing free deformation, to determine a relationship between temperature, thermal expansion, and electrical resistivity. Subsequently, piezo-resistivity experiments in steady temperature regime were performed at 25°C, 50°C and 70°C. It was found that if temperature is steady when deformation is imposed on a CNT/cement composite, the sensitivity and linearity of its electrical response are maintained. On the other hand, when temperature is in transient condition, CNT/cement composites work as a thermistor and such behavior must be considered when interpreting fractional resistivity change curves. © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of NICOM8 Chairpersons Keywords: Resistivity; temperature; self-sensing; carbon nanot-ubes; thermal expansion.

Keywords: Resistivity; temperature; self-sensing; carbon nanot-ubes; thermal expansion.

2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of NICOM8 Chairpersons 10.1016/j.prostr.2025.06.002 2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of NICOM8 Chairpersons 2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of NICOM8 Chairpersons * Corresponding author. Tel.: +55-21-393-88215; fax: +55-21-393-88215. E-mail address: oscar@coc.ufrj.br * Corresponding author. Tel.: +55-21-393-88215; fax: +55-21-393-88215. E-mail address: oscar@coc.ufrj.br