Use of fibre reinforced sand in road pavement construction

Geotechnical engineering laboratory was conducted to determine the properties of desert sand from Scotland, in order to design a flexible pavement in the urban area of Birmingham city (Uk), near to New Street station. The representation of the design has been possible through the determination of the gradation, density, angle of friction, cohesion and stiffness of desert sand, allowing to study the variation of these parameters in natural soil and treated soil at different percentages of polypropylene fibres, such as 0. 1, 0. 25 and 0. 5%. Therefore, this paper emphasizes the engineering behaviour of untreated and treated soil for pavement construction, analysing the subgrade, bottom layer of the pavement, above which the sub-base will be determined. Moreover, in both static and dynamic triaxial tests, the strength is proportional to the increase in confining pressure, enhancing the contact between particles, hence the density. The findings show that the 0. 25% of synthetic fibre (12 mm) represents the optimum rate per cent to achieve the density and the strength desirable to design the road pavement in a low thickness (261 mm) as much as possible due to the greater value of the resilient (42. 97 mpa) used. Consequently, it will reduce the cost of the construction and perform well having a good stiffness, rather than to consider the low resilient achieved with 0. 5% of fibre where it is turned out to be uneconomical due to the 462 mm of sub-base layer. Furthermore, the increase obtained is related to the homogeneity of the fibres mixed into the soil, providing tensile stress between sand and fibre when the load is applied.