Mechanical strength characteristics of fiber-reinforced pond ash for pavement application

The pavement construction sector throughout the world is facing a major challenge of non-availability of suitable construction materials. On the other side, many waste/sub-products are being generated from manufacturing/production units causing environmental pollution. One of such waste materials is pond ash produced from thermal electric power plants, which can be utilized as an alternative construction material in place of traditional materials. In this context, an attempt was made on fiber-reinforced pond ash as subbase layer of flexible pavements to understand its engineering behavior by conducting static (California bearing ratio, CBR) and dynamic (repeated load triaxial, RLT) tests. Randomly distributed polypropylene fibers of various proportions were used in pond ash as reinforcement inclusions. The test results were analyzed to address the influence of fiber on conventional parameters of pond ash such as CBR, resilient modulus (M_R), and permanent strain (ϵ_p). Also, the influence of confining (σ_c) and deviatoric stress (σ_d) levels on M_R as well as ϵ_p with load cycles have been investigated for both unreinforced and reinforced pond ash. The results obtained have shown that the inclusion of fiber improves the CBR, M_R and ϵ_p characteristics of the pond ash. With an increase in stress levels (σ_c and σ_d), the M_R of reinforced pond ash increased compared to non-reinforced ash. Irrespective of the fiber content in pond ash, permanent strain values were increased with an increase in the number of loading cycles and cyclic deviatoric stresses. However, with the introduction of fiber, the rate of strain development in pond ash was reduced significantly. Furthermore, the experimentally obtained M_R and ϵ_p values were validated against existing models established by previous researchers. From the above findings, it can be concluded that fiber-reinforced pond ash can be used effectively in pavement layer applications.