Resistance Properties to Chloride Ingress of Standard-Cured Concrete Made with an Admixture Incorporating Rich SiO2 and Al2O3

• Main Authors: Koichiro Yamato, Akira Sasaki, Takayasu Ito, Isamu Yoshitake
• Format: Article
• Language: English
• Published: SpringerOpen 2020-02-01
• Series: International Journal of Concrete Structures and Materials
• Subjects: admixture; concrete; chloride attack resistance; pore size distribution; Friedel’s salt
• Online Access: http://link.springer.com/article/10.1186/s40069-020-0391-7
• ISSN: 1976-0485; 2234-1315

Abstract In regions where the concrete structures are exposed to a salty environment, the concrete requires high resistance to chloride-ion penetration. To achieve higher resistance against chloride ingress, a pozzolanic admixture incorporating a high volume of SiO2 and Al2O3 has been developed. The admixture is a fine mineral powder with a specific surface area of 13,000 m2/kg or higher. It is typically mixed with the concrete at a cement replacement level of 5–13 mass% (20–40 kg/m3). To demonstrate the applicability of the admixture to general ready-mix concretes, this study examined the fundamental properties of concrete cured under standard conditions regarding resistance against chloride ingress. Chloride immersion tests revealed high resistance against penetration of concrete produced with the admixture. Pore-size distribution analysis confirmed that the volume of pores less than 0.01 μm diameter increased whereas a decrease of large pores occurred (0.1 μm diameter or larger). The major contributor to the high resistance was found to be the immobilization of penetrating chloride ions by the formation of Friedel’s salt.