低活性粉煤灰基层材料干缩和温缩性能试验研究

The Study on Experiments of Dry Shrinkage and Temperature Shrinkage Performances of Low Activity Fly-Ash Base Course

目的为了研究低活性粉煤灰基层材料的干缩和温缩性能,解决半刚性基层材料随着温度和湿度的变化容易产生开裂的问题.方法对不同配合比以及不同添加剂的低活性粉煤灰基层材料进行室内干缩和温缩试验研究,分析其干缩系数、温缩系数等参数随时间、失水率和温度的变化规律.结果在二灰材料中掺入适量碳酸钠,硫酸钠等添加剂情况下不仅保证了基层混合材料的早期强度,而且具有较好的抗裂性能;在混合料设计过程中,应兼顾混合料强度和收缩特性来确定水泥剂量和混合料的配合比;混合料的温缩系数随温度降低基本呈波动变化,特别是在0℃^-30℃的负温区变化幅度明显平缓,可见笔者采用的低活性粉煤灰的抗温缩性能明显优于符合规范的粉煤灰.结论在合理选用配合比和添加剂剂量的条件下,采用的低活性粉煤灰材料可以作为道路基层材料,具有较好的抗裂性能.

In order to study the dry shrinkage and temperature shrinkage performances of low activity fly-ash base course and solve the cracks problems of semi-rigid base course with different temperature and humidity.The indoor test of dry shrinkage and temperature shrinkage were carried out for the semi-rigidity base course materials with different mixture ratio and addictives.The test results have showed the changing laws of the coefficient of dry shrinkage and temperature shrinkage with the time,the ratio of water evaporation and temperature,the test results also indicate that not only the early strength of the mixture can be guaranteed,but the anti-cracking performance can be improved if reasonable amount of Na2CO3 and Na2SO4 is added to the lime-fly ash materials.Both early strength and shrinkage performances should be considered when determining the constitution of mixture ratio.The coefficient of temperature shrinkage of the mixture makes a fluctuate variations when the temperature drawing down,the variations is placid in the 0℃～-30℃ temperature specially,so,it has a better low-temperature anti-cracking performance.The anti-temperature shrinkage performance is better than normal activity fly-ash base course used the low activity fly-ash base course in this paper.In conclusion,the low activity fly-ash can be used as the base course of asphalt pavement,and its anti-cracking performance is usually better other semi-rigidity materials.