Application of Class C Fly Ash and Quarry Dust Mix for Utilization as Subbase Material in Flexible Pavement

Depleting good quality natural aggregates and soils call for the need of use of industrial by-products and waste materials in road construction. Use of wastes and by-products in road construction consume large quantities and resolve issue of their safe disposal. Class C fly ash is the by-product from thermal power plants while quarry dust is waste left behind during quarrying processes. This study investigated the application of class C fly ash and quarry dust mix for utilization in subbase layer of flexible pavement. The class C fly ash and quarry dust mixed were studied with the help of unconfined compressive strength test, repeated load triaxial test, durability test and microstructural analysis. The mixture of 90% fly ash plus 10% quarry dust was found to be suitable with respect to strength and durability criteria to be used as subbase material in flexible pavement. Owing to the formation of cementitious phases during pozzolanic reaction, proposed mix demonstrated significantly higher resilient modulus than conventional granular subbase material. The service life ratio for pavement with proposed mix is 1.2 and 1.26 in fatigue and rutting respectively compared to conventional pavement. The use of quarry dust and fly ash in large quantities in flexible pavement is an economical as well as sustainable solution for road construction.