This paper aims to use sludge, waste material, from the electricity production process for local community benefits. The chemical properties of sludge from power plant was analyzed by X-ray fluorescence (XRF). The result show that the sludge comprises high amounts of SiO2 and Al2O3 as pozzolanic materials, mixed with fly ash and Portland cement to enhance strength of interlocking brick block. From 9 ratios of mixing tested in this study, the optimal ratio is a ratio of sludge: fly ash: Portland cement at 50: 50: 10 and the optimal concrete curing time is 28 days. The maximum compressive strength was 27.75 kilogram per square centimeter (ksc) and the water absorption value is lower than 14%. The interlocking brick block made from sludge was passed the criteria of Thai Industrial Standard (TIS) and suitable for use as non load bearing construction materials. The blocks sized 10 x 20 x 10 cm. were made from optimal ratio of sludge with the construct cost less than 10 Baht/piece. The blocks were used for construction materials in 3 landmark areas of the community nearby power plant and were received good cooperation and feedback.