Rules and mechanism of aggregates fragmentation

The rule and mechanism of aggregates crushing are studied to lay a foundation for hot recycling of asphalt mixture. Gyratory compaction tests were taken to simulate aggregates crushing, and the force model of aggregates was used to analyze the mechanism of aggregates crushing. The test results show that the times of gyratory compaction have little influence on aggregates crushing since the aggregates are broken at the initial period. The fragmentation degree of aggregates with continuous gradation is lower than that of aggregates with framework gradation, while the former may produce more fine aggregate. The 4.75 mm is the mainforce bearing point, and it is the turning point of coarse and fine aggregates. In crushing process a peek is formed at 4.750 mm aggregates to construct the framework structure. The aggregates of framework structure break into the lower size firstly, and when there are enough force bearing points the aggregates would stop breaking. It is feasible to express the degree of aggregates fragmentation by the difference of sieve residue. Gyratory compaction tests can be used to simulate aggregates fragmentation.