What is geopolymer concrete and what are its advantages over Portland cement concrete?

Geopolymer concrete uses aluminosilicate materials (fly ash, slag) activated by alkaline solutions (NaOH, sodium silicate) instead of Portland cement. Advantages: 80% lower CO2 emissions, excellent chemical resistance, high early strength, good fire resistance, and utilization of industrial byproducts. Challenges include: heat curing often required (60-80C), handling of alkaline activators, variability in precursor materials, limited field experience, and higher initial cost. It's promising for precast applications and where sustainability is prioritized.