Evaluation of Mechanical and Shrinkage Behavior of Lowered Temperatures Cementitious Mortars Mixed with Nitrite-Nitrate Based Accelerator

Yusuke Tomita; Akira Yoneyama; Heesup Choi; Masumi Inoue; Jihoon Kim; Hyeonggil Choi; Yuhji Sudoh

doi:10.3390/ma13173686

Evaluation of Mechanical and Shrinkage Behavior of Lowered Temperatures Cementitious Mortars Mixed with Nitrite-Nitrate Based Accelerator

Materials (Basel). 2020 Aug 20;13(17):3686. doi: 10.3390/ma13173686.

Authors

Yusuke Tomita¹, Akira Yoneyama¹, Heesup Choi¹, Masumi Inoue¹, Jihoon Kim², Hyeonggil Choi³, Yuhji Sudoh⁴

Affiliations

¹ Department of Civil and Environmental Engineering, Kitami Institute of Technology, Hokkaido 090-8507, Japan.
² Faculty of Environmental Technology, Muroran Institute of Technology, Hokkaido 090-8585, Japan.
³ School of Architecture, Civil, Environment, and Energy Engineering, Kyungpook National University, Daegu 41566, Korea.
⁴ Basic Chemicals Department Chemicals Division, Nissan Chemical Corporation, Tokyo 103-6119, Japan.

Abstract

Recently, calcium nitrite (Ca(NO₂)₂) and calcium nitrate (Ca(NO₃)₂) have been increasingly used as the main components of salt- and alkali-free anti-freezing agents, for promoting concrete hydration in cold-weather concreting. With an increase in the amount of nitrite-based accelerator, the hydration of C₃A, C₃S, and βC₂S in the cement is accelerated, thereby improving its early strength and effectively preventing the initial frost damage. Meanwhile, with an increase in the amount of nitrite-based accelerator, the expansion and shrinkage of the concrete-and, therefore, the crack occurrence-are expected to increase. In this study, various experiments were conducted on shrinkage, crack initiation, and the development of mortar containing a considerable amount of a nitrite-based accelerator. The result confirmed that, as the amount of nitrite-based accelerator was increased, the shrinkage was increased, and cracking in early age was more likely to occur, compared to the cases without the addition of this accelerator.

Keywords: calcium nitrate; calcium nitrite; crack potential; cracking; degree of restraint; frost-resistant accelerator; pore volume; shrinkage; strength.