Evaluation of Interaction Process of Fly Ash and Clayey Soils with High Plasticity Index from Micro- Structural Point of View

Fly ash is a coal combustion product that is composed of the particulates (fine particles of burned fuel) (Dayioglu et al., 2017). In many countries fly ash is placed in landfills. Due to the vast production of this type of waste, the safe disposal of fly ash is one of the major concerns. One of the best methods to reduce the side effects of fly ash production is to re-use it in civil engineering projects (Horpibulsuk, et al., 2009). Due to the presence of Al and Si in fly ash, it shows pozzolanic properties (Phanikumar and Shankar, 2017). Therefore, in the recent years fly ash has been used in many soil stabilization or cement production projects. In spite of many researches which have focused on application of fly ash in soil stabilization, there are very limited attentions on the type of mechanism of soil- fly ash interaction (i.e. chemical or physical type). Therefore, the main objective of this paper is to investigate the interaction process of fly ash and clayey coils with high plasticity index from micro structural point of view. In other words, this paper aims to investigate on the dominant type of soil-fly ash interaction and to examine that in what extent this interaction is physical or chemical process. To achieve the above mentioned objectives series of Atterberg limits test, unconfined compression experiments, XRD testing, and digestion test were performed to address the above mentioned objectives.