A plasticiser providing unprecedent- ed two-hour-long workability of concrete, called Chrysoplast Omega 101, has been launched by Chryso South Africa. The new product created significant interest when launched by Chryso France at the Paris Batimat expo in November, last year, and will be welcomed by large- and small-scale concrete producers in South Africa, says MD Norman Seymore. He adds that the development of the new nontoxic plasticiser was as a result of Chryso customers increasingly calling for concrete – whether readymix, pumped or construction concrete, to retain its workability for longer periods; concrete plasticity at the time of pouring to maintain this workability – from batching to pouring on site; and improvement of the general aesthetics of the concrete. “These were significant technical challenges for Chryso. “In the first place, we had to design an admixture able to add record consistency to concrete, using relatively small plasticiser dosages. “Moreover, the plasticiser also had to offer flexibility, and has a more pleasing final appearance than ordinary concrete. “The new plasticiser, Chrysoplast Omega 101, is sufficiently flexible to be used within a wide range of dosages from 0,2% to 1,2% of cementitious content, ranging from low-workability concrete to fluid concrete. “Fluidity can be maintained for up to two hours to accommodate problems on site, the management of truck fleets, and to add a level of reactivity that enables the shuttering to be struck at 16 hours instead of 28 hours, even at low temperatures,” says Seymore.

He adds that the improved aesthetics of the concrete was achieved by the production of homogenous concrete devoid of bleeding characteristics.

Chryso France met the product development challenges by creating an entirely new molecule. “Chryso is the only admixture producer to have evolved structures based on the chemistry of polyoxyethylene diphosphonates. “These structures improve concrete performance and maintain workability. “Further, the company is a leader in the chemistry of polyoxyethelene polycarboxylates with, for example, the recent development of its Chrysofluid Optima and Premia ranges of new-generation water-reducing admixtures. “Given the expertise in these two areas and in organo-mineral interactions, Chryso created the molecule and Chrysoplast Omega 101 emerged,” Seymore explained.

Recent tests of the new plasticiser showed that it improves concrete cohesion substantially through maximum aggregate coating, and prevents bleed-water rising to the surface. Further, European and local trials showed that workability can be maintained for two hours, using dosages ranging from 0,3% to 0,5% of cementitious content.

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