Investigation Into Sustainable Application of Class C Fly Ash Layer in Flexible Pavement

Global demand for power generation has had an immense impact on thermal power plants that has caused a problem with fly ash disposal. Unless utilized suitably, fly ash deposits turn valuable land into dumping grounds that pose a risk to the environment and human health. In this study, the effectiveness of Class C fly ash (CFA) incorporated in a flexible pavement was investigated, which was based on laboratory and field investigations along with an environmental impact assessment. The laboratory experimentation included durability and repeated load triaxial (RLT) tests and in the field, falling weight deflectometer (FWD) tests were conducted. The test sections with a fly ash layer and a control section were constructed in the field to assess the viability of construction and service life. For the fly ash layer, the back-calculated modulus values were 4.3 and 6.5 times greater than the base and subbase of the control section, respectively. The fly ash section exhibited a service life ratio (SLR) of 1.72 compared with the control section under standard loading conditions. The energy consumed, greenhouse gas (GHG) emissions produced, and capital cost incurred in the construction of the fly ash section were reduced by 67%, 59%, and 25.7%, respectively, compared with the control section. The bulk application of fly ash was advantageous and sustainable due to better structural performance and a significantly reduced environmental impact compared with conventional base and subbase layers.