Title: Application of a New Superplasticizer for Ultra High-Strength Concrete
Author(s): K. Mitsui, T. Yonezawa, M. Kinoshita, and T. Shimono
Publication: Symposium Paper
Appears on pages(s): 27-46
Keywords: bridges (structures); coarse aggregates; compressive strength; drying shrinkage; flowability; fly ash; freeze-thaw durability; high-strength concretes; mix proportioning; setting (hardening); silica fume; slump; superplasticizers; temperature; workability
The key to casting high-strength concrete with compressive strength of more than 100 MPa into complicated reinforced structures is to give the concrete high fluidity as well as to improve strength. The authors developed an acrylic copolymer-based new superplasticizer that can improve fluidity of concrete with water-binder ratio of around 0.20. Paper presents results of a series of studies conducted to determine the properties of fresh and hardened high-strength concrete using the newly developed superplasticizer. The effect of the new superplasticizer was examined with varying water-binder ratio, type of cement, and temperature compared with conventional superplasticizers. The new superplasticizer needed a much lower dosage than conventional superplasticizers to attain a certain slump (250 mm) for a water-binder ratio of around 0.20, and it significantly reduced concrete viscosity. Sufficient workability was kept for 2 hr without much delay in setting time, while conventional superplasticizers showed large slump loss and excessive delay in setting time. Results of strength development, drying shrinkage, and freeze-thaw resistance did not show any harmful effect. Field studies were conducted on application of the high-strength concrete to a prestressed concrete bridge with design strength of 100 MPa using the new superplasticizer. Workability and strength development of concrete were tested and resulted in sufficient quality.