Activation of low calcium fly ash with cementitious material for utilization in subbase layer of flexible pavement

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4. Activation of low calcium fly ash with cementitious material for utilization in subbase layer of flexible pavement

Fly ash and ground granulated blast-furnace slag (GGBS) are by-products of thermal power plants and steel industries, respectively, which are produced in large quantities throughout the world. These materials frequently cause disposal issues as well as pollution of the environment. One of the most effective ways is the utilization of these waste materials in roadways after altering their geotechnical properties. Class F fly ash must be activated by cementitious materials such as lime, cement, and GGBS to achieve sufficient strength due to its lack of self-cementing properties. The goal of this research is to investigate the feasibility of fly ash amended with lime, cement, and GGBS as subbase material for road pavement. Extensive laboratory studies were carried out to determine the compaction properties, unconfined compressive strength, and CBR values of different fly ash-additives mixes. Based on the test results, it is found that fly ash stabilized with a minimum of 3% lime and 3% GGBS satisfies the criteria recommended by the Indian Road Congress for utilization in the subbase layer of flexible pavement. Additionally, a four-layer flexible pavement system was modelled using IIT PAVE to compute strains at the critical locations under standard axle loading.  The service life and construction cost of the pavement with stabilized fly ash in the subbase layer was compared with that of conventional pavement. This study confirms that fly ash stabilized with lime and GGBS can be used in roadwork applications with significant economical and environmental benefits.

Keywords: Fly ash; Compressive strength; Service life ratio

9th International Congress on Environmental Geotechnics (ICEG2023)

Advances in Testing and Material Characterization