{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,8]],"date-time":"2026-05-08T06:47:30Z","timestamp":1778222850518,"version":"3.51.4"},"reference-count":34,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2021,1,13]],"date-time":"2021-01-13T00:00:00Z","timestamp":1610496000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100010665","name":"H2020 Marie Sk\u0142odowska-Curie Actions","doi-asserted-by":"publisher","award":["765057"],"award-info":[{"award-number":["765057"]}],"id":[{"id":"10.13039\/100010665","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Multifunctional structural materials are very promising in the field of engineering. Particularly, their strain sensing ability draws much attention for structural health monitoring applications. Generally, strain sensing materials are produced by adding a certain amount of conductive fillers, around the so-called \u201cpercolation threshold\u201d, to the cement or composite matrix. Recently, graphite has been found to be a suitable filler for strain sensing. However, graphite requires high amounts of doping to reach percolation threshold. In order to decrease the amount of inclusions, this paper proposes cementitious materials doped with new hybrid carbon inclusions, i.e., graphite and carbon microfibers. Carbon microfibers having higher aspect ratio than graphite accelerate the percolation threshold of the graphite particles without incurring into dispersion issues. The resistivity and strain sensitivity of different fibers\u2019 compositions are investigated. The electromechanical tests reveal that, when combined, carbon microfibers and graphite hybrid fillers reach to percolation faster and exhibit higher gauge factors and enhanced linearity.<\/jats:p>","DOI":"10.3390\/s21020518","type":"journal-article","created":{"date-parts":[[2021,1,13]],"date-time":"2021-01-13T21:50:54Z","timestamp":1610574654000},"page":"518","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":54,"title":["Hybrid Carbon Microfibers-Graphite Fillers for Piezoresistive Cementitious Composites"],"prefix":"10.3390","volume":"21","author":[{"given":"Hasan Borke","family":"Birgin","sequence":"first","affiliation":[{"name":"Department of Civil and Environmental Engineering, University of Perugia, via Goffredo Duranti 93, 06125 Perugia, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2928-1961","authenticated-orcid":false,"given":"Antonella","family":"D\u2019Alessandro","sequence":"additional","affiliation":[{"name":"Department of Civil and Environmental Engineering, University of Perugia, via Goffredo Duranti 93, 06125 Perugia, Italy"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0601-9664","authenticated-orcid":false,"given":"Simon","family":"Laflamme","sequence":"additional","affiliation":[{"name":"Department of Civil, Construction and Environmental Engineering, Iowa State University, Ames, IA 50011, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5044-8482","authenticated-orcid":false,"given":"Filippo","family":"Ubertini","sequence":"additional","affiliation":[{"name":"Department of Civil and Environmental Engineering, University of Perugia, via Goffredo Duranti 93, 06125 Perugia, Italy"}]}],"member":"1968","published-online":{"date-parts":[[2021,1,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Song, G., Wang, C., and Wang, B. (2017). Structural health monitoring (SHM) of civil structures. Appl. Sci., 7.","DOI":"10.3390\/app7080789"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Karbhari, V.M., and Lee, L.S.W. (2009). Vibration-based damage detection techniques for structural health monitoring of civil infrastructure systems. Structural Health Monitoring of Civil Infrastructure Systems, Elsevier.","DOI":"10.1533\/9781845696825"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"594","DOI":"10.1785\/0220170111","article-title":"Structural health monitoring of buildings using smartphone sensors","volume":"89","author":"Kong","year":"2018","journal-title":"Seismol. Res. Lett."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"e2321","DOI":"10.1002\/stc.2321","article-title":"A literature review of next-generation smart sensing technology in structural health monitoring","volume":"26","author":"Sony","year":"2019","journal-title":"Struct. Control Health Monit."},{"key":"ref_5","first-page":"526","article-title":"Back-to-basics: Self-sensing materials for nondestructive evaluation","volume":"78","author":"Laflamme","year":"2020","journal-title":"Mater. Eval"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"110","DOI":"10.1016\/j.measurement.2014.09.048","article-title":"Intrinsic self-sensing concrete and structures: A review","volume":"59","author":"Han","year":"2015","journal-title":"Measurement"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1016\/j.compositesb.2007.02.024","article-title":"Processing and modeling of conductive thermoplastic\/carbon nanotube films for strain sensing","volume":"39","author":"Pham","year":"2008","journal-title":"Compos. Part B Eng."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1177\/1475921714560071","article-title":"Electromechanical modelling of a new class of nanocomposite cement-based sensors for structural health monitoring","volume":"14","author":"Ubertini","year":"2015","journal-title":"Struct. Health Monit."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1016\/j.compositesa.2015.01.001","article-title":"Strain and damage monitoring in carbon-nanotube-based composite under cyclic strain","volume":"71","author":"Vertuccio","year":"2015","journal-title":"Compos. Part A Appl. Sci. Manuf."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"200","DOI":"10.1016\/j.cemconcomp.2015.11.001","article-title":"Investigations on scalable fabrication procedures for self-sensing carbon nanotube cement-matrix composites for SHM applications","volume":"65","author":"Rallini","year":"2016","journal-title":"Cem. Concr. Compos."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"111763","DOI":"10.1016\/j.sna.2019.111763","article-title":"Self-sensing capabilities of cement-based sensor with layer-distributed conductive rubber fibres","volume":"301","author":"Dong","year":"2020","journal-title":"Sens. Actuators A Phys."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Buasiri, T., Habermehl-Cwirzen, K., Krzeminski, L., and Cwirzen, A. (2019). Piezoresistive Load Sensing and Percolation Phenomena in Portland Cement Composite Modified with In-Situ Synthesized Carbon Nanofibers. Nanomaterials, 9.","DOI":"10.3390\/nano9040594"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"156","DOI":"10.1016\/j.compscitech.2014.11.015","article-title":"Prediction and experimental validation of electrical percolation by applying a modified micromechanics model considering multiple heterogeneous inclusions","volume":"106","author":"Kim","year":"2015","journal-title":"Compos. Sci. Technol."},{"key":"ref_14","first-page":"599","article-title":"Self-sensing concrete nanocomposites for smart structures","volume":"10","author":"Ubertini","year":"2016","journal-title":"Int. J. Civ. Environ. Eng."},{"key":"ref_15","first-page":"138","article-title":"Electrical characteristic and piezoresistivity of carbon fiber graphite cement-based composites containing CCCW","volume":"26","author":"Xu","year":"2009","journal-title":"Acta Mater. Compos. Sin."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"188","DOI":"10.1016\/j.materresbull.2016.12.037","article-title":"Fabrication and characterization of graphite-cement composites for microbial fuel cells applications","volume":"88","author":"Frattini","year":"2017","journal-title":"Mater. Res. Bull."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Birgin, H.B., D\u2019Alessandro, A., Laflamme, S., and Ubertini, F. (2020). Smart Graphite\u2013Cement Composite for Roadway-Integrated Weigh-In-Motion Sensing. Sensors, 20.","DOI":"10.3390\/s20164518"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Birgin, H.B., Laflamme, S., D\u2019Alessandro, A., Garcia-Macias, E., and Ubertini, F. (2020). A Weigh-in-Motion Characterization Algorithm for Smart Pavements Based on Conductive Cementitious Materials. Sensors, 20.","DOI":"10.3390\/s20030659"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"025023","DOI":"10.1088\/1361-665X\/ab62e2","article-title":"Dynamic sensing properties of a multifunctional cement composite with carbon black for traffic monitoring","volume":"29","author":"Monteiro","year":"2020","journal-title":"Smart Mater. Struct."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"055013","DOI":"10.1088\/1361-665X\/ab79b9","article-title":"Structural modal identification and health monitoring of building structures using self-sensing cementitious composites","volume":"29","author":"Ding","year":"2020","journal-title":"Smart Mater. Struct."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"107488","DOI":"10.1016\/j.compositesb.2019.107488","article-title":"Piezoresistive behaviours of cement-based sensor with carbon black subjected to various temperature and water content","volume":"178","author":"Dong","year":"2019","journal-title":"Compos. Part B Eng."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"77","DOI":"10.1016\/j.solmat.2016.11.030","article-title":"Multipurpose experimental characterization of smart nanocomposite cement-based materials for thermal-energy efficiency and strain-sensing capability","volume":"161","author":"Pisello","year":"2017","journal-title":"Solar Energy Mater. Solar Cells"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1222","DOI":"10.1016\/j.matdes.2014.10.015","article-title":"Hybrid effects of carbon fibers on mechanical properties of Portland cement mortar","volume":"65","author":"Shu","year":"2015","journal-title":"Mater. Des. (1980\u20132015)"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"9495","DOI":"10.1007\/s10854-017-6693-0","article-title":"Pressure-sensitive carbon black\/graphene nanoplatelets-silicone rubber hybrid conductive composites based on a three-dimensional polydopamine-modified polyurethane sponge","volume":"28","author":"Huang","year":"2017","journal-title":"J. Mater. Sci. Mater. Electron."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Abedi, M., Fangueiro, R., and Gomes Correia, A. (2020). Ultra-Sensitive Affordable Cementitious Composite with High Mechanical and Microstructural Performances by Hybrid CNT\/GNP. Materials, 13.","DOI":"10.3390\/ma13163484"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1016\/j.conbuildmat.2018.12.203","article-title":"Self-monitoring of smart concrete column incorporating CNT\/NCB composite fillers modified cementitious sensors","volume":"201","author":"Ding","year":"2019","journal-title":"Constr. Build. Mater."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Lee, S.J., You, I., Zi, G., and Yoo, D.Y. (2017). Experimental investigation of the piezoresistive properties of cement composites with hybrid carbon fibers and nanotubes. Sensors, 17.","DOI":"10.3390\/s17112516"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"108012","DOI":"10.1016\/j.matdes.2019.108012","article-title":"Piezoresistive behaviours of carbon black cement-based sensors with layer-distributed conductive rubber fibres","volume":"182","author":"Dong","year":"2019","journal-title":"Mater. Des."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"184","DOI":"10.1016\/j.powtec.2020.06.029","article-title":"Piezoresistivity enhancement of functional carbon black filled cement-based sensor using polypropylene fibre","volume":"373","author":"Dong","year":"2020","journal-title":"Powder Technol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1016\/j.sna.2018.04.009","article-title":"Self-sensing capability of ultra-high-performance concrete containing steel fibers and carbon nanotubes under tension","volume":"276","author":"Yoo","year":"2018","journal-title":"Sens. Actuators A Phys."},{"key":"ref_31","first-page":"1395","article-title":"Smart Concrete for Enhanced Nondestructive Evaluation","volume":"76","author":"Laflamme","year":"2018","journal-title":"Mater. Eval."},{"key":"ref_32","unstructured":"SGL Carbon (2021, January 07). Sigrafil Short Carbon Fibers. Available online: https:\/\/www.sglcarbon.com\/en\/markets-solutions\/material\/sigrafil-short-carbon-fibers."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"065008","DOI":"10.1088\/1361-665X\/aa6b66","article-title":"Biphasic DC measurement approach for enhanced measurement stability and multi-channel sampling of self-sensing multi-functional structural materials doped with carbon-based additives","volume":"26","author":"Downey","year":"2017","journal-title":"Smart Mater. Struct."},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Ariyur, K.B., and Krsti\u0107, M. (2003). Real Time Optimization by Extremum Seeking Control, Wiley Online Library.","DOI":"10.1002\/0471669784"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/2\/518\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:10:34Z","timestamp":1760159434000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/2\/518"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,1,13]]},"references-count":34,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2021,1]]}},"alternative-id":["s21020518"],"URL":"https:\/\/doi.org\/10.3390\/s21020518","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,1,13]]}}}