Patent ID: 8481617

Claim:
An adjuvant system for concrete comprising as a combination of: (a) a superplasticizer; (b) an accelerator, wherein the accelerator is selected from calcium salts; and (c) 0.005 to 0.2% by dry weight based on the total binder weight of a rheology extender, wherein the rheology extender is a polyalkoxylated polyphosphonate of formula (III) or one of its salts, alone or as a mixture: wherein: R is a hydrogen atom or a monovalent hydrocarbon group including from 1 to 18 carbon atoms and optionally one or more heteroatoms; the R i are similar or different from each other and represent an alkylene such as ethylene, propylene, butylene, amylene, octylene or cyclohexene, or an arylene such as styrene or methylstyrene, the R i optionally contain one or more heteroatoms; Q is a hydrocarbon group including from 2 to 18 carbon atoms and optionally one or more heteroatoms; A is an alkylidene group including from 1 to 5 carbon atoms; the R j are similar or different from each other and may be selected from: the A-PO 3 H 2 group, A having the aforementioned meaning, the alkyl group including from 1 to 18 carbon atoms and being able to bear [R—O(R i —O) n ] groups, R and R i having the aforementioned meanings, and the group R k designating a group such as R j , —B designating an alkylene group including from 2 to 18 carbon atoms, “n” is a number greater than or equal to 0, “r” is the number of [R—O(R i —O) n ] groups borne by the whole of the Rj, “q” is the number of [R—O(R i O) n ] groups borne by Q, the sum “r+q” is comprised between 1 and 10, “y” is an integer comprised between 1 and 3, Q, N and the R j may form together one or more rings, this or these rings may further contain one or more other heteroatoms, whereby the system provides concrete with a workability of more than 30 minutes and a compressive strength Rc at 4 hours sufficient for removal from the mould.