Waste Clay Brick Binders for Low-Carbon Concrete Pavement Construction: Fid-Bau Portal

Waste Clay Brick Binders for Low-Carbon Concrete Pavement Construction

Migunthanna, Janitha / Rajeev, Pathmanathan / Sanjayan, Jay

This study investigated the use of waste clay bricks (WCB) as a binder constituent in developing low-carbon pavement-grade geopolymer concrete. Blends of WCB with slag and/or fly ash were used as the aluminosilicate source materials. Sodium silicate in powder form was used as the activator to produce dry geopolymer binders. Considering the practical applicability, concrete was produced under ambient curing. Concrete with WCB in the binder showed higher compressive strengths than the concrete with only fly ash and slag in the binder and, a significant difference in flexural strength was not observed for different binder types. Maximum compressive strength of around 56 MPa at 28 days was recorded for concrete made with the ternary blend of WCB + slag + fly ash. The strength of concrete with WCB + slag was around 42 MPa. Sealing of samples to avoid contact with atmospheric air resulted in better strengths. Drying shrinkage of WCB-based concrete was investigated following the standard test procedure by subjecting it to initial curing in lime-saturated water and by a non-standard procedure of sealed curing. Compared to the standard method, the non-standard method resulted in higher drying shrinkage due to loss of moisture from the specimen. The initial flexural modulus for WCB-based concrete was higher than the concrete with slag + fly ash binder indicating the higher stiffness of WCB-based concrete. The environmental performance of the different binders used in concrete was assessed by estimating the carbon emissions and energy consumption. Compared to using ordinary Portland cement, the use of geopolymer binders can reduce carbon emissions by 70% and energy consumption by 81%. Among the geopolymers investigated in this study, the binder with WCB + slag + fly ash showed the best overall performance.