Design and Performance of Precast, Prestressed Concrete Beams Made with Fly-ash-based Alkali-activated Concrete

This paper presents the development and implementation of a fly-ash-based alkali-activated concrete mixture for use in precast, prestressed concrete beams. Alkali-activated concrete, which contains no portland cement and often incorporates recycled materials, offers an environmentally friendly alternative to conventional concrete. The study evaluated over 40 mortar mixtures to identify a design suitable for precasting plant production. Full-scale beams and mechanical property specimens were fabricated and tested, alongside comparable portland cement concrete specimens. Results showed that the structural performance of alkali-activated concrete beams varied from code-based predictions, highlighting the need for further refinement in design and fabrication methods. The research provides practical insights into adapting alkali-activated concrete for precast applications, including lessons learned on production constraints and material behavior.