Effect of additives on dissolution mechanisms of fly ash in cementitious systems

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This proposal for a second research period is based on the first part of the research project entitled Effect of Additives on Solubility Mechanisms of Fly Ash in Cementitious Systems. The results of the investigations led to new issues which are to be clarified with suitable methods. In particular, the hy-pothesis of the catalytic action of the used organic additives during the dissolution of fly ash glass needs to be verified. Also the effect of sulphates supplied by the surface layers of fly ash on the action of the additives needs further investigation. Additionally, a dispersing action of the additives is to be considered.The research results will enable determination of the individual effects which lead to better perfor-mance of fly ash mortar made with organic additives.Furthermore, low alkali Portland cement is included in the investigations because alkalis considerably affect both fly ash and organic additives. Due to the common use of concrete admixtures, e.g. plasti-cizers, the interaction of the organic additives with concrete admixtures has to be investigated for a broadly based assessment.