Performance evaluation of geopolymer concrete pavement after five years of service

This study presents a five-year performance evaluation of a geopolymer concrete (GPC) pavement installed in 2019 in Alexandria, City of Sydney, as part of an Australian Government initiative supporting low-carbon infrastructure. The condition of the in-service GPC slab was compared with that of a companion blended cement concrete (BCC) slab, both subjected to identical traffic loads and environmental exposure. Visual inspection and testing reveal that while both slabs developed flexural and shrinkage cracks, the GPC exhibited only one flexural crack over five years, compared to three in the BCC slab. Surface abrasion was more pronounced in the GPC, resulting in greater surface loss. Cores showed that the GPC met the required design compressive strength but was 18% lower than the BCC. However, the performance difference in terms of abrasion is primarily attributed to aggregate grading and hardness – the GPC mix incorporated a gap-graded 14 mm olivine basalt. In comparison, BCC used a well-graded 8 mm granite aggregate. Image analysis confirms a higher aggregate fraction on a typical GPC surface than on a BCC surface. Petrographic analysis, along with on-site abrasion testing, indicates that aggregate hardness and grading significantly influence abrasion resistance. Both pavements have maintained their structural integrity under service conditions. The findings highlight the importance of selecting high-quality aggregates, their relative volume, and grading for pavement applications, and identify areas for improvement, including subgrade preparation and curing methods. With these enhancements, GPC has strong potential as a sustainable alternative for pavement applications and in infrastructure projects. • Five-year field performance of GPC and BCC pavements assessed under service conditions. • Direct comparison undertaken between GPC and BCC slabs under identical loading and exposure. • GPC showed greater surface abrasion due to aggregate grading and hardness. • Aggregate quality and gradation govern abrasion resistance more than binder type. • Results confirm GPC viability for pavements with optimised construction and mix design.