Application Technical Study Of Low-quality Flyash On The Lime-flyash Base Course

With the rapid development of highways, lime-fly ash base, a kind of semi-rigid base is widely used in the construction of freeway and highway. However, the quality of fly ash produced by China's power plant is extremely unstable. Over eighty percent of fly ash loss on ignition is more than six percent, some reach more than 20 percent. Poor performance as resources greatly limits the fly ash's application. It is the main reason of China's low utilization of fly ash. Chongqing area is no exception. In addition to the high quality fly ash produced by individual large-scale power plants, the quality of fly ash produced by the majority of small and medium-sized power plant is lower. It mostly indicator of Loss on ignition is not regulatory requirements. If high Loss on ignition fly ash is used to build the lime-fly ash base, it will lead to the water requirement increased, density of the base increased, and resulting in cracking and damage of the base. The production of fly ash is rich in Chongqing area. To take full advantage of the economic benefits of local fly ash, it is necessary to achieve energy conservation and reduce fly ash pollution. Not only the new ways of comprehensive utilization of fly ash should be explored, but also the quality of fly ash needs to meet the requirements. That's the key technical problem.This paper is based on the research projects "Study on low-quality fly ash in the Shuijiang - Jiushi freeway". First of all, the definition of low-quality fly ash is summarized:Low-quality fly ash is a flyash that contains a High loss on Ignition,High sulphur,One or more active ingredients can not meet the standard requirements. In order to research such fly ash, we did the following work:â‘ Research on the influence between the stability of lime-fly ash base and the content of sulfur. Results indicate that to meet the standard requirements, the SO3 content should not more than six percent. Through further study on the relationship between sulphur content and loss on ignition, the empirical formula is obtained. The formula plays an important guiding significance for the using of high-sulfur and high loss on ignition fly ash as lime-fly ash base.â‘¡Completed the test of low-quality fly ash activity provocation. Additive mixing is used to raise the strength of lime-fly ash base. The final results show that, fly ash can meet the requirements of strength by modification.