This work aims to evaluate the feasibility of using calcium aluminate composite (CAC) manufactured from steel slag, quicklycooled with high pressure air, and Acement, produced from CAC and various additives including gypsum as enhancementsfor regulated set cement. To evaluate the performance CAC or Acement as the additives of regulated set cements, CAC andAcement were replaced for the commercially available calcium sulfoaluminate cement (CSA)-based rapid setting cement(RSC). The engineering properties of workability, strength, and elastic modulus of mortar and concrete phases were thentested. From the mortar tests, as the replacement ratio of CAC was increased, the compressive strength of the mortarsignificantly decreased because of reduced amounts of gypsum for ettringite formation. On the other hand, as the replacementratio of Acement including gypsum was increased, the compressive strength increased due to enhanced ettringite formation. From the test results, Acement displayed more favorable results as an additive for the rapid setting cement than CAC. CACcontinued to show good performance at less than 10% of replacement ratio. Concrete testing revealed that mechanicalperformances of compressive, tensile, and flexural strength and elastic modulus all improved by 10% with CAC replacementand by 20% with Acement replacement. However, the resistivity performances for freeze-thaw tests and carbonation slightlydecreased.

Keywords: Ultra-rapid setting cement, Rapidly-cooled steel slag, CAC, Acement