Technical calcium nitrate as set accelerator for cement at low temperatures

• Published in: Cement and concrete research Vol. 25; no. 8; pp. 1766 - 1774
• Main Authors: Justnes, Harald, Nygaard, Erik C.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Ltd 01.12.1995; Elsevier Science
• Subjects: Admixtures for concrete, mortar and grouts; Applied sciences; Buildings. Public works; Concretes. Mortars. Grouts; Exact sciences and technology; Materials; Cement setting; Correlation; Setting agent; Efficiency; Cement paste; Calcium nitrate; Portland cement; Cement type; Room temperature; Vicat needle; Low temperature
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/0008-8846(95)00172-7

The objective was to test the efficiency of technical calcium nitrate (CN) as a set accelerator for different cements at low temperatures (5–7 °C). The applied dosages were 0.00, 1.55, 2.32, 3.10, 3.86 and 7.73 % CN of the cement weight, corresponding to 0.00, 1.00, 1.50, 2.00, 2.50 and 5.00 % NO3, respectively. Five different portland cements were chosen covering a wide range in C3A contents, since it was initially believed that the set regulating mechanism involved C3A (i.e. the efficiency depend on the C3A content). The setting characteristics of the cement pastes with wc = 0.40 were determined by an automatic Vicat-needle apparatus in a room with an ambient temperature of 5–7 dgC. The results revealed that the set accelerating efficiency of CN depended very much on the cement type. However, no correlation with the C3A content was found. On the other hand, the set accelerator efficiency of CN seems to increase with increasing belite content according to the Bogue analyses of the cements, or other cement characteristica promoting belite formation in the clinker process.