In order to solve the problem of low freeze-thaw deformation strength of railway road genes in cold regions, railway subgrade soil was improved with polypropylene fibres. The failure mechanism of fibres improved foundation soil is revealed by experiments. The test results showed the following: (1) The strength decreased with the increase in the water content in the melting state and reached its maximum when the water content was 12% in the freezing state. The strength reached the maximum when fibre incorporation was 0.3% and fibre length was 15 mm. (2) The shear strength of the improved subgrade soil gradually decreased and tended to be stable with the increase in the number of freeze-thaw cycles in the frozen state. There was no significant change with the increasing number of freeze-thaw cycles in the thawing state. (3) Before and after the cyclic loading of the fibre-modified subgrade soil, the strength after cyclic loading was greater than that before. (4) Through scanning electron microscopy, the optimal fibre content was determined to be 0.3%. The research results can provide a strong reference for the improvement of railway subgrades, and they have broad application prospects.

Biopolymer treatment of geomaterials is a promising technology with green technology potential that can help reduce global warming. It offers a positive environmental impact and a wide range of applications. This paper reports the results of a study of the mechanical performance of biopolymer-treated dune-sand from the Algeria desert. The sand was mixed with varying amounts of xanthan gum biopolymer and reinforced with polypropylene fibre. The study demonstrated that xanthan gum treatment improved the Unconfined Compressive Strength (UCS) of unreinforced sand and fibre-reinforced sand. Nonetheless, the test results revealed that biopolymer-treated sand manifested higher resistance after drying. Based on the findings, the optimal quantity of xanthan gum for treating sand is 2%. The incorporation of fibre in the matrix increases the strength and failure strain. The Scanning Electron Microscopy (SEM) analysis further substantiated that the biopolymer bonds the sand particles together and the distribution of PP fibre in the mixture, thereby enhancing compressive strength and durability. The results indicate that using xanthan gum biopolymer treatment offers an environmentally friendly approach to enhancing the mechanical properties of desert sand.

In recent years, there has been a notable emphasis on waste reduction and the adoption of recycled materials within the construction industry to reduce the industry's overall carbon footprint. This study investigates the structural performances of concrete kerb sections prepared with five different concrete mixes containing recycled concrete aggregate, recycled tyre-derived aggregates and recycled polypropylene fibres. Kerb sections were cast at a road site in a suburb of Adelaide, Australia. After the concrete hardened, sections were cut and brought to the laboratory. A large number of monotonic and cyclic load tests were conducted on the kerb sections. The loadcarrying capacity, bending moment capacity, cyclic fatigue capacity, durability properties along with deformation tolerance were evaluated. Kerb sections made with concrete containing recycled aggregate and polypropylene fibre could sustain nearly 2000 cycles of loading. Kerb sections prepared with natural aggregate concrete performed comparatively better. The addition of polypropylene fibre significantly improved the postcracking behaviour of kerb sections and can delay crack propagation and other distress when subjected to cyclic loadings such as excessive soil movement, e.g., in areas with expansive soils or prone to tree root migration. Long-term observation may be required to confirm the mechanical and durability performance improvement in real field conditions.

Kerb is an integral part of the roadway that provides structural support and facilitates drainage. When constructed over expansive soils, they face additional tensile stresses due to swelling and shrinkage caused by seasonal moisture variations. Tree roots can also exert additional tensile stresses that need to be absorbed by the kerb. Due to the relatively low deformation tolerance of concrete, premature failures are common. This study, a rigorous laboratory investigation, evaluates the effect of adding tyre-derived aggregate (TDA) and recycled polypropylene fibre on tensile strength, deformation tolerance, flexural toughness and impact resistance of concrete for potential use in road kerb construction. The effect of replacing natural coarse aggregates with recycled concrete aggregates has also been investigated. It has shown that TDA can improve deflection tolerance and polypropylene fibres can help resist larger tensile stresses. 5 % rubber with 0.66 % polypropylene fibres could be used as effective solutions in areas prone to expansive soil movement and tree root migrations.