The use of fly ash to partially replace cement in concrete is one of the effective ways of reducing the negative effect on the environment due to the use and production of cement. However, properties of concrete are strongly associated with the quality of fly ash used. This paper investigates the applicable use of raw fly ash, which is taken from Nghi Son coal power plant, Vietnam with a high loss on ignition in concrete. There are two group mixtures with different water-to-binder ratios of 0.35 and 0.45. In each group, fly ash is used to replace 10%, 20%, and 30% cement. Test results indicate that raw fly ash can be used to replace up to 20% cement with improved compressive strength. Moreover, with increasing the fly ash content, workability of fresh concrete increases while its unit weight decreases. Furthermore, all tested concrete mixtures show the good durability performance with ultrasonic pulse velocity values of greater than 4100 m/s.