Experimental investigation for the development of superior structural integrated thermocrete via incorporation of novel non-encapsulated paraffin aggregate

Abstract

Structural thermocrete was developed by the incorporation of novel non-encapsulated paraffin-aggregate (NE-PA) into the cement matrix. The preparation of NE-PA follows the intrusion of liquid paraffin into porous expanded clay lightweight aggregate (EC-LWA), tailed by subsequent exposure to heat (50 °C) to ooze-out surface paraffin until an appreciable amount (29.13%) was retained. Flow characteristics, microstructure, thermal properties, chemical characterization, and thermal stability were determined using hangerman’s cone, scanning electron microscope (SEM), differential scanning calorimeter (DSC), fourier transform infrared spectroscope (FT-IR), and thermo-gravimetric analyzer (TGA) respectively. Moreover, to evaluate the mechanical characteristics in terms of compressive and flexural response three mixes were formulated via 0%, 50%, and 100% replacement of EC-LWA by NE-PA, and tested at 7 and 28 days of curing age. Results showed that a self-flowable and non-segregating mix was achieved for all the thermocrete compositions. Omission of the encapsulation layer (in NE-PA) resulted in an ameliorate interfacial transition zone (ITZ) that was enriched with nano-silica fume (NSF) inclusion, providing a substantial increase in mechanical properties. At 28 day curing age, compressive strength was increased by 47.26% and 26.58% for both the respective compositions. Moreover, 100% replacement by NE-PA resulted a maximum of 44 MPa compressive strength and rupture modulus of 4.03 MPa at 28 day, confirming its applicability in sustainable structures. Load–deflection also curve showed rational improvement (14%) in overall fracture toughness. The retained thermal energy storage capacity of structural thermocrete via DSC analyses was determined to be 20.48 J/g. Achievement of thermal stable and superior structural thermocrete with thermal properties as good as the available literature provided the opportunity that the encapsulation layer can be eliminated for practical application practices in sustainable construction.