Properties of concrete incorporating high volumes of ASTM Class F fly ash

Abstract

This thesis presents the results of research performed in developing high-volume fly ash (HVFA) concrete incorporating ASTM Type I cement and ASTM Class F fly ash from Big Brown Power Plant of TU Electric, Texas. In HVFA concrete, the proportion of fly ash was 58 percent by weight of the total cementitious materials, the water and cement content were kept low at 115 and 155 k g/M3 , respectively. A broad range of engineering properties was investigated including compressive strength, flexural strength, splitting-tensile strength, Young's modulus of elasticity, drying shrinkage, resistance to freeze-thaw cycling, pore structure and activation energy. A preliminary economic analysis was also performed on HVFA concrete. The HVFA concrete evaluated in this study had satisfactory workability and setting characteristics. It also exhibited excellent mechanical properties with satisfactory early age strength and good long-term strength development. The HVFA concrete had relatively low drying shrinkage and a very fine pore system. Excellent durability under freeze-thaw cycling was also found for the air-entrained HVFA concrete. Results from activation energy test show that strength gain of the HVFA concrete under isothermal curing conditions could be modeled appropriately using Plowman's logarithmic strength-age model. The relative strength-maturity relationship was established for the HVFA concrete containing various percentages of additional gypsum. The HVFA concrete investigated was determined to be cost effective. It was shown that about two and half dollars per cubic meter could be saved through savings on portland cement.