This paper presents a feasibility study on the effects of forest based ash (FBA) on the mechanical performance of concrete. Four such samples were obtained from the pulp and paper industry as the residual byproduct of their hog fuel. They were analyzed for grain size distribution, density, morphology, and oxide content. Subsequently, the ash was employed as a cement substitute (up to 20% by mass) and the resulting concrete was examined for mechanical properties. Results show that all four FBA samples were coarser than Portland cement with mean particle size around 100–1000 microns. Further, X-ray fluorescence showed that the FBA samples were predominantly composed of CaO, with significant amounts of SO3 and alkali oxides at levels that exceed maximum limits allowed for the latter by ASTM. This poses concerns on durability. Nevertheless, based on short-term compressive and tensile performance alone, this study shows that FBA could replace up to 15% by mass of cement.