Evaluation of Spiral-Blade Concrete Mixer, Shelbyville Reservoir Project Shelbyville, Illinois

摘要

The purpose of this investigation was to evaluate the effectiveness of a 4-1/2-cu-yd-capacity, stationary-drum concrete mixer with a spiral blade being used by the U. S. Army Engineer District, St. Louis, to mix concrete for the spillway at Shelbyville Dam. Batches of four concrete mixtures were mixed, sampled, and tested for coarse aggreate content, unit weight of air-free mortar, and water and cement content of the mortar. Test results for concrete having a slump of 2-1/2 plus or minus 1 in. indicated that the mixer would satisfactorily mix 4 cu yd of 3-in., or smaller, maximum-size-aggregate concrete and 3 cu yd of 6-in. maximum-size-aggregate concrete in either 2 or 1-1/2 minutes. One-minute mixing time was insufficient to blend the constituents into a uniform mass. Two-minute mixing did not give satisfactory mixing for relatively harsh mixtures (1-1/4-in. slump or less). (Author)