Open AccessDelaying Effect of NaCl on The Conversion of Hydrates of Calcium Aluminate Cement
Author(s) -
Zhong Ping Wang,
Hao Yang,
Ya Ting Zhao,
Ling Xu,
Jiang Wang,
Da Li Jia
Publication year - 2019
Publication title -
iop conference series. materials science and engineering
Language(s) - English
Resource type - Journals
eISSN - 1757-899X
pISSN - 1757-8981
DOI - 10.1088/1757-899x/678/1/012107
Subject(s) - aluminate , curing (chemistry) , hydrate , cement , calcium , porosity , chemistry , metastability , chemical engineering , materials science , nuclear chemistry , mineralogy , metallurgy , polymer chemistry , organic chemistry , engineering
The effect of NaCl on the conversion of hydration products of calcium aluminate cement(CAC) was determined by means of MIP, XRD, DSC-TG and SEM. Results show that the addition of NaCl promotes the formation of CAH 10 at early hydration stage. The total porosity and proportion of harmful pore in hardened CAC paste with NaCl are lower and the 7d-strength is 40% higher than that of the control. The later curing at 40°C accelerates the conversion from metastable C 2 AH 8 , CAH 10 to C 3 AH 6 , and the strength decreases with the increasing of curing age. After 90 days, there is no metastable hydrate detected in CAC paste. However, the addition of Niacin CAC paste can prominently delay the conversion of C-A-H. Massive CAH 10 still exists in the paste with NaCl, resulting in a slower retraction of late strength.