An experimental study on strength improvement of expansive subgrades by polypropylene fibers and geogrid reinforcement

Abstract

The rapid development of infrastructure often encounters the loose subgrades and is becoming difficult to carry to construction activities. Numerous counteracting methods are developed to control the swelling-shrinkage behavior of the expansive subgrades. The mechanical stabilization of the expansive subgrades by reinforcing with the polypropylene fiber and geogrid is sustainable. Geogrids and polypropylene fibers have been used extensively to strengthen the expansive subgrade and foundations as individuals. The polypropylene fiber reinforcement enhanced the reinforced expansive subgrades's tensile strength capacity, wherein the geogrid reinforcement is the quick fix mechanical stabilization technique, which reduces the pavement failures. In this research, the polypropylene fiber and geogrid reinforcement’s combined effect has been evaluated to stabilize the pavement subgrades. The various mechanical strength test such as unconfined compressive strength (UCS) and large direct shear box test was conducted to evaluate the mechanical interaction between expansive subgrades, polypropylene fiber, triaxial geogrid, and biaxial geogrid at the interface. The polypropylene fiber of 12 mm length was used in the proportion of 0.25%, 0.5%, and 1.0% and single geogrid layer at mid-depth. The result shows that reinforced subgrades’ shear strength with a layer of biaxial/ triaxial geogrid and polypropylene fiber increases by 177%. It is also observed that the unconfined compressive strength of the expansive subgrades increased ranging 3.8–139.6% with the inclusion of polypropylene fiber with geogrid in different combinations. The combined reinforcement method shows an effective treatment methodology to improve the property of expansive subgrades.

Microstructural and mechanical characterization of expansive soils for sustainable stabilization purposes

“…Microstructural analysis involves examining aspects such as the size and shape of apertures, the arrangement of ribs, and the material composition of the geogrid. These factors in uence how well the geogrid interacts with the soil, providing stability, reinforcement, and drainage as needed [51]. Physical property analysis delves into the geogrid's mechanical behaviour, including its tensile strength, exural rigidity, puncture resistance, interface friction, and water permeability.…”

Research on the interface characteristics of coal gangue with different geosynthetic reinforcements

“…Upon reaching a certain threshold of shear displacement, the interfacial shear stress stabilized. TIWARI and SATYAM's [18] large-scale direct shear and unconfined compressive strength tests on the interaction at the interface between the subgrade, polypropylene fibers, triaxial geogrids, and biaxial geogrids revealed that the shear strength of the reinforced subgrade increased by 177% with the addition of bi/triaxial geogrids and polypropylene fibers. CEN et al [19] developed a large-scale composite shear test apparatus to study the shear behavior of various geomembrane interfaces, observing higher peak shear stresses and shear displacements on textured geomembrane-soil interfaces compared to smooth ones.…”

Triaxial Test of Coarse-Grained Soils Reinforced with One Layer of Geogrid

“…While it has been acknowledged that different laboratory experiments can effectively replicate the behavior of soil and geogrids in specific components of embankments [15], a significant portion of these tests has been carried out using the direct shear apparatus [16]. These experiments encompass diverse aspects, such as different soil types, particle sizes, soil densities, and moisture contents [17][18][19][20][21], as well as variations in the type of geogrids, aperture sizes, and shapes [22][23][24][25]. An important parameter found to increase the reinforcement effect is the number of geogrid-reinforcement layers [26].…”