PROCESSING AGGREGATES TO IMPROVE PARTICLE SHAPE

摘要

Particle shape has an influence on the performance of aggregates in most applications. For uses such as hot mix asphalt, crushed aggregate base and Portland cement concrete, shape plays a major role either in the preparation and placement or in the performance of the product, or both. For other applications such as drainage layers, drainfields, erosion control, etc., shape plays a minor role. Properties such as shear strength, stability, voids and density, as well as workability and finishability are all influenced by particle shape. Processing of aggregates is the single most important factor in determining particle shape. During the production of crushed aggregates, particle shape can either be improved or diminished, depending on the selection and operation of crushing equipment. A preliminary task of research study ICAR 102 -Increased Use of Fines in Portland Cement concrete, was the processing of over 40 aggregate sources through a vertical shaft impact crusher. The goal was to produce multiple fine aggregate products for each source having a wide range of particle shape and gradings having high fines contents. These products would be evaluated for use as fine aggregate for concrete. The equipment proved to be beneficial in producing fine aggregates from coarse aggregates and in reshaping fine aggregates. In both cases, fine aggregates having good particle shape were produced.