i have read an article regarding sugar affecting time setting of cement. How this is so? have several theories but none was so convincing to me.
Good question! my thought is that it works through the OH groups interfering with the reactions of the differnet phases with water in the same way that sulphonated superplasticizers interfere / compete with sulphate reaction to form ettringite.
It is not only sugar but I have seen no reaction at all with a 1:1 water/methanol mix.
Sugars have been known for their retardation effect for a long time. The common hypothesis is that retardation arises from adsorption on a hydration product (see the work of Thomas, N. L. and Birchall, J. D. (1983). Cem. Concr. Res. 13, 830). In addition, Taylor has an excellent review of the mechanisms of retardation by sugars in his "Cement chemistry" (pp. 346-349 in 2nd edition).
How about the possibility of changing roles at a certain amount of sugar? From retarder to accelerator.
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