Abstract:
Fly ash is a by-product of the combustion of pulverized coal in thermal power plants. Tyre buffing is a by-product of waste auto tyres and is elongated in shape and can be utilised as fibre reinforcement elements. They can be mixed with local soils available near the construction sites to create a new soil mix, as an effective means of disposal and utilization without adversely affecting the environment. Laboratory investigation is necessary to determine the engineering properties of the new soil mixes.
In the present investigation, the influence of randomly oriented tyre buffings on the triaxial compression behaviour of clayey soil-fly ash mixes has been studied. A Class F fly ash and waste car tyre fibres were added as additive and reinforcement material to a clayey silt soil. Compacted specimens were prepared at the corresponding optimum moisture content and maximum dry density, and then cured for different durations.
The results indicate that the stress-strain relationship and ductility of the specimens are substantially affected by the inclusion of the two waste materials. When fly ash alone is added to the soil, the stiffness and peak strength increase whereas ductility is reduced. When tyre fibres are added to the soil-fly ash mixes, strength decreases and the behaviour changes to a ductile one. A mass of 35% fly ash content and 10% tyre fibres content are considered to be the optimum for blending with the soil. The use of fly ash and waste tyres along with fine-grained soils in geotechnical projects will increase the recycled volume, and will reduce the environmental impact.
