Fly ash is a byproduct in the thermal power plant station that is produced from combustion of coal and identified as hazardous material. Many global researchers have been attempted over the long years for effective utilisation of fly ash a sustainable construction material. In Bangladesh, only 10%-15% fly ash is used in cement manufacturing industry for producing the Portland composite cement (PCC) and concrete industry to be cost effective as well as minimise the costly disposal processes. This paper reported the experimental investigations that were carried out to study the effectiveness of fly ash, lime and dredges sediment on the strength development of block as an alternative building material. Fly ash was partially replaced with four percentages (30%, 35%, 40% and 45%) and again was replaced with other four percentages (25%, 30%, 35% and 40%) including 5% of lime by weight. The study observed the greater strength and water absorption resistant performance on the specimen made by 35% fly ash and 5% lime at 28 days curing age. The outcomes of the study can be applied in the construction sectors for making decision to use the studied building materials for cost-effective and eco-friendly manner.