Electric induced curing of graphene/cement-based composites for structural strength formation in deep-freeze low temperature

摘要

A novel electric induced curing method is introduced in this paper in order to solve the problem of cold region construction. This method applies alternating voltage (AC) to the fresh graphene/cement-based composite to generate ohmic heating, which can helps to accelerate the hydration reaction and form the structural strength of cement-based materials in deep-freeze low temperature. Graphene nanoplatelets (GNPs) were utilized to form conductive path in the fresh cement-based composite, thus reducing electrical resistivity. Numerical and experimental study was conducted to quantify the bridging behavior of GNPs and an optimum amount of GNPs of 2.0 vol% is determined as the global GNPs connection threshold. The graphene/cement-based composite by electric induced curing at -20 degrees C experiences an internal temperature rise and has superior mechanical properties. Further, the structural homogeneity of the hardened cement-based composite was confirmed using the nondestructive ultrasonic evaluation and microhardness measurement by one-way analysis of variance. Moreover, SEM, Raman spectra and MIP results show that the electric induced curing can accelerate the cement hydration leading to denser microstructure at low temperatures. This work provides insights into the quality control of cement-based materials for cold weather construction by means of the convenient and energy-efficient electric induced curing. (C) 2018 Elsevier Ltd.