Development of structural thermal energy storage concrete using paraffin intruded lightweight aggregate with nano-refined modified encapsulation paste layer

Nano-refined epoxy paste is formulated using the optimum fractions of nano-silica fume and graphite powder to effectively encapsulate the aggregate storing phase change materials. The refined recipe offered delays in setting by 3–3.5 hrs accompanied with 15 times reduction in the thickness of coated layer, contributing in added workability, reduced consumption and strong adhesion to the established interfacial bond. The developed macro encapsulated phase change materials were found to be thermally stable, chemically compatible and thermally reliable. The melting and freezing temperatures were determined as 17.12 °C and 32.90 °C respectively with the latent heat storage capacity of 12.6 J/g. The developed thermocrete via 100% integration of macro-encapsulated aggregates showed compressive strength of more than 15 MPa and owed the potential to conserve energy by lowering the internal temperature (6.4 °C), resistance to high fluctuation in temperature while maintaining a narrow range (22 °C−30.2 °C) and by shifting the energy loads during peak periods (15-min).