Effect of Coarse Aggregate Shape and Texture on Self-Compactability

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Title: Effect of Coarse Aggregate Shape and Texture on Self-Compactability

Author(s): J.M. Tobes, L. Anahí, G. Giaccio, and R. Zerbino

Publication: Special Publication

Volume: 253

Issue:

Appears on pages(s): 13-24

Keywords: coarse aggregate type; mortar flowability; self-compacting concrete; shape; texture

Date: 7/31/2008

Abstract:
The shape and texture of coarse aggregate affect the properties of fresh and hardened concrete. However, there is limited information about the effects of aggregate characteristics on self-compactability, which can be relevant in countries like Argentina, where a large variety of aggregates is available even in the same region. This paper analyzes the effect of shape and texture of coarse aggregate on self-compacting concrete (SCC) properties. Three different types of coarse aggregate were selected: granitic crushed stone, quartzitic crushed stone, and a siliceous river gravel. The granitic crushed stone presents irregular shape, rough texture, and low absorption. The quartzitic crushed stone also has irregular shape and rough texture, but it has high water absorption. Finally, the natural siliceous river gravel is composed by strong particles with smooth surface and low porosity. SCC was prepared using each type of coarse aggregate with 19 mm maximum size and similar particle size distribution. Slump-flow, V-funnel, and J-Ring tests were carried out. Effects of the changing volume of batched and mixing energy were also studied. The homogeneity of the coarse aggregate distribution was evaluated along vertical cuts on 1 m in height tubes and along a U-tube with 1.80 m height, measuring the ultrasonic pulse velocity and the unit weight in different sections. In addition, the compressive strength and modulus of elasticity were determined. From the results, was concluded that, as expected, the shape and texture of coarse aggregate modify the flowability, but also the mixing energy can strongly affect the plastic viscosity of SCC.