Laboratory investigation of rheological properties and scaling resistance of air entrained self-consolidating concrete

An experimental investigation was undertaken to analyze the influence of va rious admixtures on the rheological properties and scaling resistance of se lf-consolidating concrete. Such concrete is intended for use as a repair ma terial for filling highly restricted areas, such as forms with closely spac ed reinforcing steel bars. Several self-consolidating concrete mixtures hav ing slump flow of 550 + 50 mm were Prepared with water-to-cement ratios var ying between 0.35 and 0.41. The mixtures were cast with 0 and 3 percent sil ica fume, with and without air-entraining admixture. All concretes incorpor ated superplasticizer and viscosity-modifying admixture to enhance deformab ility and stability. Rheological parameters (yield value and plastic viscos ity) were measured using a concrete viscometer. The air content, unit weigh t, and consistency were also determined. The consistency was assessed using the slump flow and L-Flow methods. Tests performed on hardened concrete in cluded compressive strength at 28 days (ASTM C 39), scaling resistance (AST M C 672), durability to freezing and thawing (ASTM C 666) and measurement o f the air-void parameters (ASTM C 457). Relationship between the simple slump flow and yield value and plastic visc osity measurements determined using a concrete viscometer are also discusse d. In general, the laboratory test results indicate that it is possible to produce a frost durable, self-consolidating concrete with low yield value a nd high plastic viscosity (for such fluid concrete) which can be used as a repair material to fill. highly restricted areas.