Experimental study on the road performance of reduced density fly ash–clayey sand subgrade mixtures from the Yellow River floodplain

To address challenges in subgrade construction using Yellow River floodplain soils, this study developed a reduced density filler by mixing aged fly ash with locally sourced clayey sand. The research aimed to establish a robust framework for bridging the gap between pavement design specifications (resilient modulus, E0) and construction quality control (compaction degree, K), enabling performance-based quality assurance. Laboratory experiments evaluated compaction characteristics, California Bea