Fiber Cement Composites with Failure Detection Function. (2016)

• Record Type: Journal Article
• Authors: Nešpor, Bohdan; Junek, Jiří; Nejedlík, Martin; Čechmánek, René
• Is Part Of: Procedia engineering. Volume 151(2016)
• Page Start: 183
• Page End: 190
• Publication Date: 2016
• Subjects: Electrically conductive cement-based composite -- detection of structural defectss -- attenuation of electromagnetic field; Engineering -- Congresses; Engineering -- Periodicals; Engineering; Conference proceedings; Periodicals; 620.005
• DOI: 10.1016/j.proeng.2016.07.375
• Languages: English
• ISSNs: 1877-7058

Abstract

Abstract: The article presents results of the research focused on multifunctional advanced materials with special properties. The aim of the research activity is to develop an electrically conductive cement-based composite which enables detection of failures in material structures caused by explosions, bullets or explosion fragments. The piezoresistive material should react to changes in the state of stress in building structures by changing its electrical properties. The paper closely describes mechanical, electrical and piezoresistive properties of the tested materials. The influence of different carbon and metal components on the conductivity of the concrete composite, its piezoresistivity and failure detection function under high-speed ballistic loading were tested. Electromagnetic shielding efficiency was additionally measured on the test detection composites. The test results did not confirm the need for the exclusive use of carbon ingredients but rather they confirmed their suitability for reducing the impedance where electrically conductive reinforcement is not used. It was proved that better conductivity does not automatically mean better detection sensitivity. Too low initial impedance of the composite adversely increases the demands on the sensitivity measuring tool. The detection composites are pressure-sensitive, they changed the impedance not only during the mechanical pressing but also during the mechanical clamping of samples for ballistic testing. Differently conductive cementitious composites enable the detection of failures in material structures caused by fast dynamic load. They change the impedance not only the failure of the matrix by projectile but also after projectile impact without breaking the matrix.