Optimizing Reactive Powder Concrete Mixtures for Producing Thin Precast Elements

In this project several reactive powder concretes (RPCs) were studied. In particular the paper studied their mechanical performance in relation to the type of cement used, the dosage of silica fume, and the amount of steel fibers. Compressive strength, flexural strength, and tangent elastic modulus was monitored with age for RPCs prepared with a water to cement ratio of 0.25. Silica fume was added to the mixture at a dosage up to 27% by weight of cement. An acrylic-based superplasticizing admixture was used at a very high dosage of about 10% by weight of cement in order to achieve very fluid workability. Optimum mechanical performance was obtained for the mixture prepared by using steel fibers at 20% by weight of cement and by adding silica fume at 26% by weight of cement. This mixture was characterized by 28-day compressive strength of 145 MPa, flexural strength of 35 MPa, and tangent elastic modulus of about 57 GPa. On the basis of experimental results, the use of reactive powder concretes for manufacturing thin precast elements appears to be competitive with other and more traditional methods and technologies.