The researchers studied how changing the amount of water used in making self-compacting concrete affects its strength when coal fly ash and bottom ash are added. They tested different mixtures with varying amounts of ash replacements and found that reducing the water-to-powder ratio increased the strength of the concrete. Mixes with 15-35% fly ash gained strength of around 40-60 MPa after 90 days. Using up to 20% bottom ash and 25-35% fly ash produced concrete with a compressive strength of 40-50 MPa. This shows that adjusting the water-to-powder ratio and ash percentages can help make strong self-compacting concrete.