Waste Clay Brick as a Part Binder for Pavement Grade Geopolymer Concrete

Geopolymer concrete (GPC) was developed using one-part binders made from a mixture of waste clay brick (WCB) powder, fly ash, and slag in the precursor. Its suitability for use in rigid pavement construction was evaluated based on fresh properties, hardened properties, and durability characteristics. The effects of sealed and unsealed ambient curing and the size of the WCB particles on the strength of the GPC were also examined. Sealed ambient curing significantly increased the strength of the GPC, with longer sealing periods resulting in even stronger concrete. Sealing prevented water loss from the samples and reduced carbonation, protecting the concrete from microcracks caused by dehydration. The GPC created in this study met the basic strength requirements for use in rigid pavement applications, with 28-day compressive strengths above 40 MPa and flexural strengths above 4.5 MPa. All GPC samples had a water absorption of more than 5%, with a maximum of 7.4%. The apparent volume of permeable voids was less than 14%, which is the maximum allowable value for a 40 MPa pavement-grade concrete. The GPC was resistant to abrasion and cyclic wetting and drying, and experienced only a slight reduction in compressive strength after being subjected to these cycles. There were no significant differences in the wearing depth of the top and bottom surfaces of the slabs, indicating better compaction and homogeneity of the mix.