Investigation on effects of different crushing stages on morphology of coarse and fine aggregates

ABSTRACT

The present study evaluates the effects of three different stages of crushing mechanism, namely two stage (2S), three stage (3S) and four stage (4S) on various morphology parameters (i.e. angularity, texture, flatness & elongation, sphericity and form2D) of aggregates. The 2S crushing consisted of primary and secondary crushers as Jaw and HSI (horizontal shaft impactor), respectively, while 3S crushing was composed of primary, secondary and tertiary crushers as Jaw, Jaw and HSI, respectively. In other word, 3S consisted of an additional jaw crusher compared to 2S crushing. Likewise, 4S crushing had primary, secondary, tertiary and quaternary crushers as Jaw, Jaw, HSI and VSI (vertical shaft impactor), respectively. The 4S had an additional VSI crusher to 3S crushing. Three coarse and three fine aggregate sizes were used in the study. A digital device, Aggregate Image Measurement System was used to measure various morphology parameters of aggregates and to assess the effects of stage crushing. The coarse aggregates were subjected to angularity, texture, sphericity and flatness and elongation, while fine aggregates were studied for angularity and form2D. A systematic statistical analysis was conducted to compare the mean value of aggregates shape parameters and draw logical conclusions. It was observed that effects of crushing on aggregate shape are a cumulative function of stage crushing, crushing mechanism and aggregate size. The outcome of the present study may be helpful in understanding effects of stage crushing mechanism on shape parameters of aggregates for quality production. Further, the study can assist in selection of an appropriate source of aggregate and crusher health monitoring via morphological characterisation of aggregates.

KEYWORDS:

• Morphology
• horizontal shaft impactor
• vertical shaft impactor
• angularity
• texture
• sphericity
• flatness and elongation
• form2D