Incineration has the advantages of reducing mass and volume of the solid waste and collecting energy from the combustible content simultaneously. The main by-product of MSW incineration is bottom ash (BA). This paper examines the effects of partially replacing Ordinary Portland Cement by Bottom Ash from Reppie Waste to energy plant. The paper tried to characterize the chemical and physical properties of BA, assessing workability of blend of cement and Bottom ash by slump test method, compressive strength of cement and BA blend and potential environmental concerns of heavy metals from the BA in using BA and cement blend. The research aims to determine the optimal amount of Bottom Ash for production of high-grade mortar. The samples of Bottom Ash were prepared in five different proportions (0, 10, 15, 20& 25 wt %) and design mix ratio of 1: 2.0:0 with a 0.45 w/c ratio to make 45 prismatic mortar samples. The chemical composition analysis of Reppie Bottom Ash satisfied the requirement of ASTM C618-00.At replacement less than 25 %, the initial and final setting time variation was so small that it will hardly affect the requirements of construction. Mortar with the addition of MSWIBA had remarkably reduced workability. Uniaxial Compressive Strength test of results 7 and 28 curing days were compared to control cement mortar sample. 10 % replacement of Bottom ash was an optimum replacement in this research with compressive strength of 38 MPa less than by 6 % with the control meets the requirement of the standards according to EN 196-1. Toxicity Characteristic Leaching Potential test (TCLP) result shows that the raw Bottom ash contains high concentrations of Cu, Cd and Zn. The cement matrix is known to be more stable than phases of raw materials. The TCLP leaching concentrations of the target metals of mortar mixtures were all lower than TCLP thresholds except Cd.