PROPERTIES OF SOME BLENDED HIGH-ALUMINA CEMENTS

The compressive strength of concretes made from mixtures of 'Ciment Fondu' high-alumina cement and granulated blastfurnace slag has shown an increasing trend up to 5 years when kept under vater at 20-degrees and 38-degrees-C. Concretes made from neat HAC have shown much reduced strength at 38-degrees-C after only one week, following the well known 'conversion' reactions. The presence of slag and of pozzolanas such as microsilica and metakaolin in blended HAC is responsible for the formation of stratlingite in the hydrated product and the opportunity for reactions leading to the 'conversion' phenomenon to proceed is severely limited. The sulphate resistance of mixtures of HAC and ggbs is excellent. Concretes made from blended HAC containing ggbs are expected to show a much lover rise in temperature when placed than those made from HAC alone. The-hydration chemistry of blends of Ciment Fondu and several mineral admixtures has been studied using conduction calorimetry, x-ray diffraction, thermogravimetry and electron beam microanalysis.