Self-sensing performance of metakaolin geopolymer with carbon nanotubes subjected to repeated compressive loading

Abstract

Alkaline activated binders showing enhanced piezoresistive properties have recently attracted increased interest in research of their application in smart self-sensing components. This study is focused on metakaolin geopolymer mortar doped with 0.05 and 0.10% carbon nanotubes, a conductive filler that effectively increases electrical conductivity without considerable deterioration of mechanical properties. Self-sensing performance of composites incorporated with electrodes and attached strain gauge was tested during different regimes of compressive loading cycles with continuous monitoring of strain and resistivity. Although the differences in sensitivity and repeatability were observed, all samples including the reference material have shown good response to applied loading.

Combined Experimental and Computational Prediction of the Piezoresistivity of Alkali-Activated Inorganic Polymers

“…The piezoresistivity of the inorganic polymer was significantly higher than that reported in prior studies of inorganic polymers under cyclic loading. Inorganic polymers without conductive additives have FCR below 1% when measured with direct current under cyclic loading. , The use of alternating current increases the detectable FCR by a factor of 10, opening the door to future use of inorganic polymers as self-sensing materials. Portland cement is known to have negligible FCR under cyclic loading conditions …”

“…Generally, they exhibit high mechanical properties and are considered a low-cost and environmentally friendly alternative to Portland cement because they can be synthesized from industrial byproducts that are rich in aluminum and silicon oxides, such as blast furnace slag and coal fly ash . Alkali-activated inorganic polymers have been investigated as a matrix material for self-sensing composites with conductive additives. − However, their intrinsic piezoresistivity was found to be negligible with conventional measurement methods.…”