Concrete is the most favorable material in building infrastructures such as road and bridges.Until recently, Portland Cement becomes the most active component and usually with the highest unit price and CO2emission, compared to other components, that is why appropriate use and the most economical balanced amountwith desired properties,becomes the objectives of mix proportion.Fly ash is by product of coal utilizationwhich categorized as hazardous and poisonous materialwith pozzolanic propertieswhich gives advantageson workability, mechanicaland durability propertieswhen utilized with Portland cementin concrete structures. In several literature, the recommended utilization of flyash in concrete is limited up to 25 %.From laboratory trial and bridge application, the utilization of flyash up to 45%, as portlandcement replacement, result in flow of fresh concrete of 600 mm, compressive strength of 50 MPaat 28 days and high density of hardened concrete, with total cementitious content of 491 kg/m3 and 0,25w.c.f.These result in cost savings and environment mitigation and becomes an applicable and environmentally friendly technology.