Smart construction strategies: Incorporating fly ash in sustainable city infrastructure through optimized dry lean concrete mixes

The increasing volume of industrial waste, particularly fly ash, poses significant environmental challenges. This study explores the innovative utilization of stabilized pond ash in road construction by optimizing its incorporation into layers of Dry Lean Concrete (DLC) for robust pavements. Fly ash was stabilized using hydraulic binders, particularly gypsum and Ground Granulated Blast Furnace Slag. Twenty-seven experimental mixtures were subjected to a series of laboratory experiments assessing compaction, unconfined compressive strength (UCS), and durability. The optimal binder mixture of 77 % fly ash, 5 % gypsum, and 18 % GGBS was determined using Response Surface Methodology (RSM) and Analysis of Variance (ANOVA). Meeting the requirements of IRC:SP-49 for rigid pavement construction, the best mix achieved a 7-day UCS of 2.1 MPa (standard deviation ±0.23 MPa) and a resilient modulus of 1100 MPa. A low cumulative mass loss of 4.8 % during a durability assessment over 12 wetting-drying cycles demonstrated improved resistance to environmental exposure. This approach offers a technically viable and sustainable solution for flexible pavement construction while resolving fly ash disposal challenges, hence promoting the circular economy.