Properties of one-part geopolymer pedestrian blocks made using 100 % waste materials

Ordinary Portland Cement (OPC) is one of the most commonly used construction materials. However, the production process of OPC significantly contributes to environmental degradation, underscoring the urgent need for sustainable alternatives that can reduce the construction industry's carbon footprint. One such alternative is geopolymer concrete. This study focuses on the development of pedestrian blocks made from one-part geopolymer concrete, using 100 % waste materials such as fly ash, slag, and recycled asphalt aggregates. Additionally, recycled plastic was incorporated in varying proportions of 0.5 %, 1 %, and 1.5 % by volume of the binder materials. The physical and mechanical properties of the geopolymer concrete blocks—including density, water absorption, abrasion resistance, skid resistance, compressive strength, and flexural strength—were thoroughly investigated. Given the focus on waste material utilization, assessing the environmental impact is essential. The Global Warming Potential (GWP) was selected as a key metric to evaluate the carbon footprint (measured in kg CO₂-equivalent) of the materials used in the geopolymer pedestrian blocks. Results indicated that although mechanical strength decreased with increasing plastic content, the blocks maintained adequate strength for pedestrian use up to a certain percentage of plastic incorporation. In terms of GWP, the inclusion of plastic waste led to a slight increase; however, the overall GWP of the blocks remained low due to the use of waste materials. This paper discusses the effect of recycled plastic on the tested properties, and the results indicate that one-part geopolymer concrete blocks can be effectively used for pedestrian applications, meeting standard requirements with the inclusion of plastic up to a specific volume.