Mechanical properties of ultra high performance self compacting concrete with different mineral admixtures

Abstract

Preparation and microstructure of ultra high performance concrete (UHPC) have been intensively analyzed In the last few years. The mechanical properties (compressive strength and flexural strength) were investigated under different curing conditions (standard and steam curing). Silica fumes have characteristics that make them necessary in cement composites with ultra strength properties. The search for substitute products thus appears important if the use of UHPC is to become more widespread in the concrete industry. Possibilities of making ultra high performance self compacting concrete (UHPSCC) with materials available in Serbia, based on experimental work are discussed in this paper. Three series of samples were made with different types of fine reactive additives (silica fume was replaced with metakaolin at 20% and 40% and with fine fly ash at 20%). The produced mixes had self compacted consistency. The 28(th) day compressive strength varied between 165 and 195 MPa for the heat treated specimens and between 135 and 150 MPa for the ones that had not been heat treated. Furthermore, this paper presents SEM micrographs of C-S-H phase formed after steam curing and super-heated steam under preassure.