Investigation on the Performance of High-Volume Fly Ash Concrete Reinforced with Fibers for Rigid Pavement

Fly ash has significant potential in high-volume fly ash concrete (HVFAC) due to its favorable physico-chemical properties. Extensive research in India and abroad has examined its strength and performance characteristics. In India, most ready-mixed concrete plants in the private sector commonly use 20–30% fly ash as part of the cementitious material, whereas several government agencies remain cautious. At construction sites with batching plants, typical fly ash replacement levels are around 25–30%. In contrast, site-mixed concrete using tilting drum mixers rarely uses fly ash directly, though blended cements containing 22–32% fly ash are widely used; in fact, nearly 60–70% of cement produced in India is blended. HVFAC generally replaces more than 50% of cement with fly ash and requires very low water content. To maintain workability, high-range water reducers or superplasticizers are used. Although HVFAC exhibits lower early compressive strength than conventional concrete, it develops excellent long-term strength along with improved elastic modulus, flexural, tensile, and abrasion performance. Research at CANMET-MTL in Canada initiated the development of HVFAC in 1985, with an emphasis on low cement content, a low water-to-binder ratio, and fly ash contents of up to 55%. HVFAC offers reduced CO₂ emissions, lower environmental impact, and improved durability, making it suitable for mass and structural concrete applications.