The work has shown that, in concrete, tailored polycarboxylate admixtures can reduce the water content by up to 30% and improved lignosulfonate admixtures can reduce the water content by up to 25%. In both cases these reductions are achieved with acceptable workability retention and without retardation of strength development. The same or higher strengths are achieved with blended cements and it is possible to increase the proportion of industrial by-products, such as fly ash and silica fume, in the binder from a total of 30% up to 40% by weight.
Such reductions in the water content have the potential to bring about considerable improvements in the durability of concrete because lower water contents mean lower absorption and permeability, which in turn mean that the aggressive agents (sulfates in solution and water for freezing/thawing and wetting/drying) cannot gain access to the cement matrix to cause damage.
The results confirm the validity of the tailoring approach to superplasticiser development and enable the industrial partners to offer improved products to the market.
|Title of host publication||Proceedings of the 12th International Congress on the Chemistry of Cement|
|Editors||JJ Beaudoin, JM Makar, L Raki|
|Place of Publication||Montreal|
|Number of pages||12|
|Publication status||Published - 2007|