Effect of carbonation on bulk resistivity of cement/carbon nanofiber composites. (25th October 2021)

• Record Type: Journal Article
• Authors: Gawel, Kamila; Wenner, Sigurd; Edvardsen, Laura
• Is Part Of: Construction & building materials. Volume 305(2021)
• Publication Date: 2021-10-25
• Subjects: Cement -- Composite -- Carbon nanofibers -- Conductive -- Bulk resistivity -- Carbonation; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.124794
• Languages: English
• ISSNs: 0950-0618

Abstract

Graphical abstract: Highlights: Cement with carbon nanofibers undergoes faster carbonation compared to cements without fibers. Carbonation affects material electrical properties. First formation of carbonated layer contributes to increased resistivity. Next, leaching of calcium carbonate contributes to resistivity decrease. Cements with carbon nanofibers can be used in sensing of chemical degradation. Abstract: The conductivity of cement/carbon nanofiber (CNF) composite materials has previously been shown to be affected by parameters such as e.g. CNF content or water to cement (w/c) ratios, water saturation and temperature. However, whether and to what extent chemical processes like cement carbonation can affect the electrical conductivity of cement/CNF materials remains unexplored. To investigate this the resistivity changes upon carbonation of Portland G cement/CNF composites were followed for more than 4 months. An increase in resistivity was observed within the first weeks of carbonation followed by a plateau and a subsequent decrease after 4 months. The changes in resistivity were correlated with the progress of the carbonation front followed using X-ray tomography. The magnitude of the resistivity changes was found to be related to w/c ratio. Volumetric changes affecting the connectivity between the CNFs can explain the resistivity changes.