PURPOSE: To shorten initial set time and to accelerate reduced temp. setting by incorporating set-accelerating compounds and methylol derivatives of amino acids into a set-accelerating admixture.
CONSTITUTION: A hydraulic cement set-accelerating admixture is obtained by adding a first compound which is obtained by methylolation of an amino acid and is expressed by formula (I) (wherein L is a bivalent organic group, for example, phenyl group, methylene group and ethylene group; (n) is 0.1; A is an acidic group, for example, sulfonate group; R1 is H, methylol group, a group bound to L and forming an alicyclic structure; M is H, cation) to the set- accelerating compound (e.g. mixture of calcium nitrate/calcium nitrite of 1:3 to 3:1 at weight ratio) at 0.5 to 20 wt.% to tatal sum of both. The hydraulic cement set-accelerating admixture is added to a hydraulic cement composition at 0.2 to 3.0 wt.%. Further, effective methylol derivative of the amino acid is obtained by methylolation at molar ratio of amino acid to formaldehyde in the range of 1:0.25 to 1:4.
RESURII EI JIYAADEIN
ARA EI JIEKUNABORIAN
