<p>A concrete additive comprises polyethyleneimine compounds selected from the group consisting of (1) poly¢acidic group(s) and/or acidic group(s) substituted-alkyl group(s) and/or acidic group(s) substituted-acyl group(s)!polyethyleneimine and (2) poly ¢acidic group(s) substituted-alkyl and a group selected from the group consisting of carbamoylalkyl and hydroxy substituted-alkyl! polyethyleneimine; the additive improves the flow properties of cement compositions and in particular facilitates high flow rates during pumping.</p>
