Cyclic heating and mechanical properties of CNT reinforced cement composite

The heating performance of cement composites can be improved by adding carbon nanotubes (CNTs); however, cyclic heating by CNTs can reduce the heating and mechanical properties of CNT-reinforced cement composite in the long term. This study investigated the cyclic heating and mechanical properties before and after the heating of CNT-reinforced cement composites. Paste specimens were fabricated using the 0.1-0.5 wt% con tent of CNT as the major variable, and a cyclic heating experiment was performed for applied voltages of 50 and 100 V. The compressive strength before and after cyclic heating were measured and compared. In addition, microstructural changes of the CNT-reinforced cement composite after cyclic heating was evaluated by thermogravimetric analysis, mercury intrusion porosimetry, and scanning electron microscopy. As the dosage of CNT increased, the temperature of the specimen increased, and as the heating cycle increased, the heating performance tended to decrease. This seems to be attributed to the occurrence of microcracks by the different thermal expansion coefficients, and by the additional hydrates generated by the increased temperature of the specimen.