Title: Resistance Properties to Chloride Ingress of Standard-Cured Concrete Made with an Admixture Incorporating Rich SiO2 and Al2O3
Author(s): Koichiro Yamato, Akira Sasaki, Takayasu Ito and Isamu Yoshitake
Appears on pages(s):
Keywords: admixture, concrete, chloride attack resistance, pore size distribution, Friedel’s salt
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 exam-ined 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 admix-ture. 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.