Improvement durability of cohesive soil using CKD and RAP.

The use of waste by-products materials such as cement kiln dustand reclaimed asphalt pavementin soil stabilization aims to improve the mechanical properties of soils in which more sustainable soils can be existed. The influence of wetting and drying cycles on the strength of soil stabilized by cement kiln dust and reclaimed asphalt pavement as well as the investigations of the microstructure of such blends are evaluated in this study. High plasticity clayey silt soil was under investigation. The results showed that there was a significant increase in the unconfined compressive strength, which reflected the soil strength. In contrast to control soil samples, which collapsed in the first cycle of wetting and drying, soil mixtures stabilized by cement kiln dust and reclaimed asphalt pavement passed the cycles of wetting and drying with a constant volume and no dramatic weight loss. The weight loss of the mixture of soil with 20% cement kiln dust and 35% reclaimed asphalt pavement was 2.64%, as a lowest loss. Moreover, the unconfined compressive strength of samples stabilized by cement kiln dust significantly increased after conducting wetting and drying tests compared to that of tested samples before the test. The unconfined compressive strength of soil stabilized by 20% cement kiln dust increased to 5.85 MPa after performing the durability test compared to its value of 2.68 MPa before the test. On the other hand, there was a slight change in the unconfined compressive strength value of soil stabilized by mixtures of cement kiln dust and reclaimed asphalt pavement after conducting the durability test. The formation of compounds with cementitious properties in the structure of stabilized soils was proven by microstructural analysis using scanning electron microscope. [ABSTRACT FROM AUTHOR]