Set-retarding admixture for calcium sulfoaluminate cements

摘要

A set-retarding admixture for calcium sulfoaluminate cements, comprises at least one phosphono alkyl carboxylic acid and/or salt thereof, and at least one carboxylic acid and/or salt thereof, the phosphono alkyl carboxylic acid having the structure EMI ID=1.1 HE=32 WI=27 LX=481 LY=681 TI=CF PCwherein R is independently selected from -H, EMI ID=1.2 HE=17 WI=36 LX=1226 LY=921 TI=CF EMI ID=1.3 HE=26 WI=31 LX=450 LY=1118 TI=CF PCand n is an integer from 3 to 6, with the proviso that at least one R is PO(OH)SB2/SB. The phosphono alkyl carboxylic acid may be 2-phosphono - 1,2,4- butane tricarboxylic acid and the carboxylic acid may be tartaric acid. The phosphono alkyl carboxylic acid may be the sole retarder present in a cementitious formulation comprising a calcium sulfoaluminate cement.