矿料粒径对拌和时间的影响与梯次拌和技术

Influence of Mineral Particle Size on Mixing Time and Phase Mixing Technology

为了研究双卧轴搅拌器在分批拌和沥青混合料的过程中粗细集料、矿粉和沥青的投料顺序对混合料质量与拌和效率的影响,通过建立搅拌模型分析集料颗粒在搅拌器作用下的滚动规律;根据滚动过程中颗粒表面发生沥青迁移的拌和机理,得出在沥青迁移量以一定速率递减的条件下,拌和均匀性与颗粒滚动圈数之间的关系表达式。用不等直径平面圆模型求得拌和过程中不同粒径颗粒之间的滚动关系,提出达到相同油膜厚度的粗集料、细集料、矿粉与沥青之间的梯次拌和工艺;研发了与实体工程中使用的搅拌器结构和搅拌原理相同的实验室用双卧轴搅拌机,并对AC-16混合料进行了试验研究。结果表明:在同一拌和过程中,颗粒大小不同时滚动次数有差异,矿粉滚动次数大于细集料,细集料滚动次数大于粗集料,导致不同粒径颗粒表面裹覆的油膜厚度发生变化;采用梯次拌和工艺可以提高沥青混合料的质量和设备生产效率,较之传统拌和工艺得到的沥青用量有所降低,并可减少约30%的拌和时间。

In order to investigate the influence of the adding order of coarse aggregate,fine aggregate,mineral powder and asphalt on the quality and efficiency of asphalt mixture in the process of the mixing,the rolling rule of particles under the action of double horizontal shaft mixer was analyzed by establishing a mixing model. According to the mixing mechanism that asphalt migration occurs on the surface of particles in the process of the rolling,a relational expression between mixing uniformity and particles rolling laps was obtained under the condition that asphalt migration quantity decreased at a certain rate.The rolling relationship between different size particles in the mixing process was calculated through the model of ranging diameter planar circle. Based on the relationship,the technology of phase mixing was put forward. The coarse aggregates,fine aggregates and mineral powder had the same oil film thickness.The double shaft mixer used in laboratory was developed,with the same mixer structure and mixing principle as the mixer used in the practical engineering. The experiment was conducted by dint of AC-16 asphalt mixture. The results show that different particles sizes have different rolling times in the mixing process. The rolling times of the mineral powder are greater than that of fine aggregates,whilst the rolling times of fine aggregates are greater than that of coarse aggregates. Hence,particles with different sizes have different oil film thickness on the surface. The quality of the asphalt mixture and efficiency of mixer can be improved by the phase mixing. Compared with the traditional mixing technology,the amount of asphalt decreases,and the mixing time of the phase mixing can be reduced by 30%.