Improvement the pavement Soil Subgrade Properties with Polypropylene Fibres and Its Effect on the Thickness of Pavement Layers: An Experimental Study.

Hakeem, Beshoy M

doi:10.22059/ceij.2025.387273.2206

Improvement the pavement Soil Subgrade Properties with Polypropylene Fibres and Its Effect on the Thickness of Pavement Layers: An Experimental Study.

Articles in Press

Author

Beshoy M Hakeem

Civil Engineering Department, Higher institute of engineering and technology

10.22059/ceij.2025.387273.2206

Abstract

In this study, Fibres (polypropylene fibre) were used and mixed with soil at random to strengthen the subgrade soils in flexible pavements. For the purpose of increasing soil strength, fibres were added in different amounts (0.25–1.5%) by dry weight of soil. To evaluate the compressive strength and shear parameters of subgrade soil, ( CBR ) test, Modified proctor test and unconfined compression test were carried. The results revealed that, the maximum unconfined compressive strength value, cohesion of subgrade soil, and the maximum CBR value are found at 1.0 % polypropylene fibre content. However, as more fibre is added to the soil, the percentage improvement starts to decrease. Also, the results show that as the fibre content increases, the maximum dry density decreases and the optimum moisture content increases.
In addition, six preliminary correlations are established between the fibre content and the expected percentage increase in compressive strength, CBR value, cohesion, optimum moisture content, and percentage reduction in maximum dry density.
In addition to, the case study results exhibited that treatment of the subgrade soil by 1.0% of polypropylene fibre reduces the pavement layer thickness and the cost of the pavements.

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