Production Of Aggregates From Rock On Rock Vertical Shaft Impact Crusher For Asphalt Pavement Application

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Date
2010-12
Authors
Prakash Babu, Raphuel Saravana
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Publisher
Universiti Sains Malaysia
Abstract
Physical and mechanical properties influence the suitability of aggregate for roadway construction. Physical properties include particle shape, particle size, size distribution, surface texture, void content and water absorption while mechanical properties include resistance to effects of applied traffic loads such as point load test and aggregate impact and crushing value. A study was conducted by optimizing the performance of the Metso Barmac RoR VSI crusher in producing high quality aggregates in terms of physical and mechanical properties. Seventy five crushing tests had been conducted by varying the rotor speeds from 1540 rpm to 4620 rpm and cascade ratio from 0% to 50%. Results from the conducted crushing test work showed that, highest proportion of cubically shaped aggregates produced at highest rotor speed of 4620 rpm with 0 % cascade for all three type of products namely Product A, B and C which measured at 34.60 %, 54.12 % and 45.55 % respectively. At these operating parameters, crushed products; namely Product A, B and C in conjunction with higher cubicity exhibited with lower flakiness index, valued at 7.94 %, 6.69 %, and 7.08 % respectively. Where else elongation index measured as 11.89 %, 7.92 % and 10.04 % for Product A, B and C respectively. Finer portion possessed low uncompacted voids content of 45.65 %, 44.88 % and 44.48 % for Product A, B and C respectively. Crushed products also reshaped and showed more homogeneous and uniform surface texture with higher values of point load strength index measured at 11.42 MPa, 11.80 MPa and 11.71 MPa for Product A, B and C respectively. Crushed products also possessed lower impact and crushing aggregate values. Aggregate Impact value for Product A, B and C measured as 22.22 %, 20.98 % and 20.60 % respectively, meanwhile Aggregate Crushing Value measured as 18.11 %, 17.44 % and 18.00 %. Product A, B and C possessed with lesser water absorption characteristics which measured at 0.590 %, 0.522 % and 0.599 % respectively. Crushed products which were more cubically in shape had enhanced the Marshall Stability of the asphalt specimen up to 16.59 kN, 18.11 kN and 17.78 kN for Product A, B and C respectively.
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Keywords
Production of aggregates from rock on rock vertical shaft impact crusher , for asphalt pavement application
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