"EVALUATION OF METAKAOLIN FOR USE AS SUPPLEMENTARY CEMENTITIOUS MATERIAL"

Abstract

Three types of metakaolin were evaluated for use as supplementary cementitious materials in cement-based systems. The metakaolins were calcined at 745± 2 °C for three duration periods, (1/2, 1.0 and 1.5) hrs respectively. The water-to-cementitous ratio used was 0.40. In this study, the early age properties of fresh self-compacting concrete and the mechanical properties of hardened concrete were examined. Early age evaluations aimed to determine the reactivity of metakaolin and its effect on mixture workability (slump-flow, T50, L-box, U-box and V-funnel). Compressive, tensile and flexural strengths and elastic modulus were measured at various concrete ages. Further more, two non-destructive test methods, ultra-sonic pulse velocity and Schmidt rebound hammer test were used at 7, 28 and 90 days. The results obtained from this study indicated that when the time of calcining metakaolin increased from (0.5 to 1.0) hrs and (0.5 to 1.5) hrs the compressive strength increased by (5-12) %, (12-18) %, (3-9) %, (16-21) %, (4-7) % and (12-16) % at 7,28 and 90 days respectively. Specimens in flexure, splitting, static modulus of elasticity, U.P.V and rebound number show similar behavior to those in compression.