This work studies the mechanical properties of the soil cement brick and soil cement brick mixed with fly ash from the east of Thailand, Rayong province. The purpose is to develop the new low cost materials used in the local area of Thailand. Results show that the average of the compressive strength and the modulus of rupture (MOR) of soil cement brick mixed with Eastern Rayong fly ash are lower than those of non-fly ash soil cement brick. Also both properties values increase with increasing cured time. However, the thermal conductivity shows the decreasing trend with increasing fly ash content. By conclusion, considered by mechanical properties show that soil cement brick mixed with an Eastern Rayong fly ash can efficiently produce as the structural clay load- bearing tile.