INFLUENCE OF TYPE OF DEICER ON SALT SCALING OF FROST DAMAGE

• Published in: Cement Science and Concrete Technology Vol. 67; no. 1; pp. 95 - 101
• Main Authors: HANEHARA, Shunsuke, OYAMADA, Tetsuya, KANNO, Hanaka, NAKAMURA, Daiki
• Format: Journal Article
• Language: Japanese; English
• Published: Japan Cement Association 25.02.2014
• Subjects: Deicer; Deterioration mechanism; Freezing-thawing method; Freezing-thawing resistance; Magnesium hydroxide; Salt scaling
• ISSN: 0916-3182; 2187-3313
• DOI: 10.14250/cement.67.95

In order to evaluate resistance of salt scaling of concrete, the new evaluation test method with small amount of sample for short period was investigated in this study. Test method proposed was as follows：Mortar cured after 28 days was cut into cubes of less than 1cm. Various deicer solution of 40ml is poured into 100ml polypropylene vessels with three cubes of mortar（about 4g）. Freeze and thaw cycles charged these vessels. After several cycles, these cubes were observed and sieved with 2.5mm. Each residue was weighed. The freeze-thaw resistance was evaluated by use of the residues of each sieve. The residue of each sample was also characterized by SEM and mercury porosimetry. Salt scaling resistance remarkably differs by the kind of deicers used. It was obtained that according to freeze-thaw cycles, crack proceeded from the surface to center of cubes through the transition zone between aggregate and cement paste by the deterioration of SEM image and pore structure of cubes residue. Salt scaling resistance with magnesium chloride, magnesium acetate and magnesium nitrate is proved be quite smaller than those with other deicers, because magnesium hydroxide were precipitated on the surface of concrete with each magnesium salt solution and film of magnesium hydroxide have a role to protect concrete surface from salt scaling.