Molecular design and testing of organophosphonates for inhibition of crystallisation of ettringite and cement hydration

Early hydration of Portland cement studied under microgravity conditions

“…For example, Goetz-Neunhoeffer et al present that when this mineral is precipitated from a clear solution, then at pH = 9.5 long needles with an aspect of $20 result whereas under the same conditions at pH = 12.5, very stocky crystals (aspect ratio 4.5) are formed [24]. Similar effects have been described for many admixtures including sugar [25], phosphonates [26] and superplasticizers [27]. Especially for polycarboxylate-based superplasticizers it has been described recently that they can act as strong morphological catalyst for ettringite, and that they can impact the size as well as the aspect ratio of the crystals [28].…”

An atomic force microscopy and molecular simulations study of the inhibition of barite growth by phosphonates

“…Even when more than two active phosphonate groups were present on the organic molecule, adsorption was assumed to require only two of these groups. Using these principles, inhibitors have been designed and shown to be effective [5][6][7][8][9]. lones et al Traditionally, the adsorption of molecules to mineral surfaces has been indirectly investigated from bulk experiments.…”

Reduction of Concrete Expansion by Ettringite Using Crystallization Inhibition Techniques

“…Organic compounds, such as sugars, hydroxylated carboxylic acids, lignosulfonates, and polyacrylic acids, are added to cement to retard the setting process (Young, 1972;Collepardi et al, 1984;Jolicoeur and Simard, 1998;and Taylor, 1990). Recently, experiments have been conducted on the effectiveness of phosphonate-based organic inhibitors in the cement retardation process (Coveney and Humphries, 1996;Coveney et al, 1998). Those authors found that some phosphonates are effective at inhibiting the growth of ettringite.…”