Study On Early Age Performance Of Lime-Fly Ash Base Course At Low Temperature

Lime-fly ash base course has been widely used in road construction because of its excellent performance and low cost, but it also has some limitations inevitably. For example, its early strength is low, and the construction is greatly influenced by temperature. To overcome these weaknesses, this paper has developed strength-accelerate compound activator for lime-sea-discharged ash concrete on the basis of further study on strength formation mechanism.At first, the nature of raw materials and the structure of lime-fly ash concrete had been researched to determine the proportion of the mixture. According to the influence mechanism on strength, several activators that can increase strength at low temperature were selected to carry on orthogonal test. The optimal component and dosage of activator would be achieved through analyzing the test result.Compared to those without activator, lime-fly ash concrete test-pieces using above-mentioned activator were made according to standard method, and the curing condition was divided into natural and standard curing. The test result indicated that early strength of lime-fly ash concrete test-pieces with activator were greatly increased at zero to three degrees centigrade, specifically their unconfined compressive strength on the seventh day is almost the same as that on the twenty eighth day of test-pieces without activator, thus it can reduce curing time and shorten the construction period markedly. Through paving the test road, early performance of lime-fly ash base course under the influence of activator was analyzed and economic and technical evaluation was given.This paper pioneered the concept of maturity to lime-fly ash base course research. The theoretical calculation formula between strength and maturity was achieved through curve fitting. Mutual prediction between strength and maturity is available by using the formula. It would provide theoretical basis for practice process arrangement.Experimental research shows that: reasonable activator formula can effectively improve the early performance of lime-fly ash base course at low temperature, expand its application range, increase the dosage of sea-discharged ash, and all in all achieve social and economic benefits. Results in the paper will provide theoretical basis and technical guidance for the application of lime-fly ash base course.