Chemical investigation and process optimization of glycerine pitch in the green production of roofing tiles

High embodied carbon of concrete and waste generation from the oleochemical industry pave an alternative way for the sustainable utilization of glycerine pitch (GP) and used cooking oil (UCO) in the production of roofing tiles. In this study, a mixture of UCO and GP, known as blended organic binder (BOB) was utilized to produce Eco-Roofing tiles, namely BOB-RT. To prepare the specimen, the BOB with percentages varied from 5 to 11% was blended with a mixture of fly ash and fine sand. The weight ratio of fly ash and fine sand is 35: 65. The mixture was then moulded and heat cured at 190 °C for 24 h. The chemical and mechanical properties of the cured specimens were investigated through Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), transverse breaking strength, water absorption, permeability, and porosity tests. A preliminary investigation on the effect of BOB at different mixing ratios was assessed. The highest flexural strength of 12.605 MPa was achieved by a specimen when 10% of BOB (GP: UCO 30:70) was utilized. However, the hygroscopic effect of GP and fly ash led to the high water absorbability (10.81–20.13%) of the specimen. This issue can be addressed by the addition of dodecanedioic acid or by applying a UCO-based protective layer. The results revealed that the water absorbability of the specimen was significantly reduced by 56.8%. In addition, the feasibility of GP as a sole binder in the production of roofing tile (known as GP-RT) was investigated too. The optimized GP-RT produced from 12% of GP possessed a maximum flexural strength of 6.32 MPa with 4.46% of water absorption, which can be qualified as a proper roofing tile according to ASTM standards. From the environmental perspective, the embodied carbon and embodied energy of the Eco-Roofing tiles are relatively lower than the conventional roofing products.