08-08-2014, 11:18 AM
Particle Shape and Surface Texture of Aggregates
The shape and surface texture affect the properties of fresh concrete more than the properties of hardened concrete.
Rough-texture, and angular particles require more water to produce workable concrete than do smooth, rounded and compact particles. For both crushed or noncrushed aggregate, proper gradation gives the same strength for the same cement factor.
Bond between cement paste and a given aggregate generally increases the particles surfaces change from smooth and rounded to rough and angular. The increase in bond is important for selecting aggregates for concrete where strength at early age is important.
Aggregate should be free of flat or elongated particles. Because they require an increase in mixing water and thus may affect the strength of concrete particularly in flexure.
The shape and surface texture affect the properties of fresh concrete more than the properties of hardened concrete.
Rough-texture, and angular particles require more water to produce workable concrete than do smooth, rounded and compact particles. For both crushed or noncrushed aggregate, proper gradation gives the same strength for the same cement factor.
Bond between cement paste and a given aggregate generally increases the particles surfaces change from smooth and rounded to rough and angular. The increase in bond is important for selecting aggregates for concrete where strength at early age is important.
Aggregate should be free of flat or elongated particles. Because they require an increase in mixing water and thus may affect the strength of concrete particularly in flexure.