Evaluation of West Texas natural zeolite as an alternative of ASTM Class F fly ash

Test results indicated that the natural zeolites used in this study satisfied with chemical requirements of ASTM C 618 Standard Specification. The mixture also met the minimum compressive strength activity indices at 7 days and 28 days for Type N and Type F (ASTM C 618), but showed slightly lower strength at 91-day when compared with fly ash mixtures. Moreover, zeolite mixture generated less heat of hydration and reduction of drying shrinkage when compared with the control and fly ash mixtures. The mixture showed considerably higher resistance to alkali-silica reaction as well as sulfate attack. However, zeolite mixture required a high water demand and showed lower workability than mixtures with fly ash because of high fineness, honey-comb structure, and angular shape of zeolite.