Effect of carbonation curing regime on electric heating performance of CNT/cement composites

Abstract

Carbonation curing is a widely used technique in the construction industry due to its effect in trapping CO2 in cement matrixes and reducing carbon emissions. However, the use of carbonation curing in the production of functional cementitious composites has rarely been reported. Herein, the effects of carbonation curing regime on the electric heating performances of carbon nanotube (CNT)/cement composites are investigated. Four different CNT contents are used to fabricate the samples, and the samples are cured under three different curing conditions. The electrical and thermal conductivities as well as compressive strengths of the samples are examined. Their physicochemical properties are investigated via X-ray diffraction and thermogravimetric analyses, and their CO2 uptake levels are calculated. The electric heating performance is evaluated in terms of maximum heating temperature and heat-induced electrical resistivity under cyclic heating condition. Results show that the CO2 uptake levels increase with the amount of CNT since the CNT can develop the porous structures, and it can increase the environmental impact reduction level. Meanwhile, an excessive CO2 curing can decrease the electrical conductivity and lower the electrical heating performance of the samples. In addition, the CO2 uptake level is significantly affected by the percolation threshold of the CNT. In this context, the CO2 curing regime is required to set based on the intended functionality of the CNT/cement composites.