Hydration reaction and hydrated products of low heat Portland cement-expansive additive-CaO·2Al2O3 system with/without CaCl2

Low heat Portland cement (LHC) containing expansive additives can reduce the temperature stress and the crack generation of concrete, therefore it can be used for producing mass concrete and high-strength concrete. However, since LHC does not contain much aluminum, it is difficult for LHC to immobilize chloride ions and be used in salt damage environments such as seashore. CaO·2Al2O3 addition to LHC can be the countermeasure, however chloride immobilization in LHC with CaO·2Al2O3 has not been researched in detail. This paper describes the influence of CaCl2 addition on hydration of LHC containing an expansive additive and CaO·2Al2O3. In LHC containing an expansive additive, ettringite was mainly generated with and without CaCl2. In contrast, in LHC containing an expansive additive and CaO·2Al2O3, monosulfate was generated without CaCl2, and Friedel’s salt were generated with CaCl2. Therefore, LHC containing an expansive additive and CaO·2Al2O3 showed potential for chloride ion immobilization.