Abstract:
Phayao Lake is an important semi-natural freshwater lake in Phayao province. The alluvium, in particular sedimentary soil, is currently causing a serious problem for Phayao Lake as it reduces the lake capacity. The government agency in Phayao province tries to dredge and pump out sediment every year. A large amount of sedimentary soil is inappropriately dumped around the lake, and is not put to good use. This paper aims to study the engineering characteristics of Phayao Lake sedimentary soil as improved by Portland cement type 1 and/or fly ash from Mae-Moh power plant. The sedimentary soil was improved by adding Portland cement at 0-10% and fly ash at 0-20%. The testing of the modified compaction test and the unconfined compression test were carried out on the specimens at the curing age of 7, 14, 28, 60, 90 and 120 days. The study also performed durability testing by wetting and drying methods. Finally, the result of unconfined compression test was analyzed by a multiple regression equation and a variable control equation. The study shows that the regression model and variable control model have more than 80 percent confidence. Thus, the models can predict the behavioral shear strength of sedimentary soil that is improved by cement and fly ash at Phayao Lake. It can also contribute towards further research that study about Phayao Lake sedimentary soil.