Title: Rheological Properties of Superplasticized Concrete
Author(s): Shinzo Nishibayashi, Kiyoshi Yamura,
and Shoichi lnoue
Publication: Symposium Paper
Appears on pages(s): 441-466
Keywords: admixtures; cement pastes; chemical analysis; fresh
concretes; mix proportioning; mortars (material); plasticizers;
rheological properties; vibration; viscosity; water-cement ratio;
workability; yield strength.
Generally the flow of fresh concrete is assumed to represent distortion as a Bingham body. In this study, in order to clarify the effects of chemical ad-mixtures on the flow of fresh concrete, rheological values such as the plastic viscosity and yield value (shearing stress) of fresh paste and mortar with superplasticizer were experimentally investigated both with and without vibration, Four types of chemical admixtures, sulfonated naphthalene-formaldehyde condensates, sulfonated melamine-formaldehyde conden-sates, poly-condensed aromatic sulfonate and a conventional water reducing agent (modified lignosulfonate) were used, and various water/cement ratio, sand/cement ratio, and consistencies, with and without chemical admixture, were selected for the mix pro-portions of test samples. The apparatus used in this study was designed to conduct experiments on the rheological phenomenon of fresh concrete under vibration. The frequencies of vibration em-ployed were 0, 100, 120, 150 and 180 Hz with accelerations of 0, 2, 4 and 6g. The plastic viscosity and yield value of vibrating cement paste and mortar through which a sphere moves can be calculated from Stokes's law. The results obtained have provided useful in-formation for identifying the fundamental rheological properties of the plasticizing concrete.