# A Comparative Study of the Pullout Strength of Geostraps and Geogrids in Reinforced Soil
## 1 Introduction  
Soil reinforcement is a common geotechnical technique used to improve the strength, stability, and overall performance of soil, especially in weak or challenging ground conditions. The mechanical behaviour of soil is improved by introducing reinforcing materials, including geosynthetics, natural fibres, and cementitious agents [1, 2, 3]. The application of this technique is particularly critical in the construction of embankments, retaining structures, subgrade enhancement, and slope stabilisation. Contemporary advancements in soil reinforcement have emphasised integrating sustainable methods and eco-friendly materials. For instance, natural fibres such as bamboo, coir, and jute have been investigatedas sustainable alternatives to synthetic reinforcements [4]. Exploring novel soil blends, including frozen soil mixtures, also provides temporary reinforcement during excavation or tunnelling operations by temporarily increasing the stiffness and bearing capacity in cold regions or artificial ground freezing applications [5; 6]. Geosynthetics, such as geogrids and geotextiles, are also widely utilised to offer soil confinement and tensile resistance, increasing load-bearing capacity and minimising deformation [7], leading to better ride comfort [8]. The interaction between the soil matrix and the reinforcing material significantly influences the overall system performance, with parameters such as interface friction, bond strength, and pullout resistance as critical design considerations [9]. Using geosynthetics in civil engineering has significantly advanced the design and construction of reinforced soil structures. Materials such as geogrids, geotextiles, and geostraps have been pivotal in improving the mechanical behaviour of soil, enabling applications in retaining walls, embankments, and other geotechnical projects [10; 11; 12]. Geosynthetics serve as reinforcements by providing tensile strength, enhancing soil stability, and ensuring durability under various loading conditions [13]. Among these materials, due to their unique characteristics, geostraps have emerged as a promising alternative to traditional geogrids. This study evaluates the pullout behaviour of the geostrap, comparing its pullout performance with that of the biaxial geogrid [14]. The pullout test is a widely recognised method for assessing the interaction between soil and reinforcement materials. It simulates the conditions experienced in reinforced soil structures, where the bond strength between the soil and the reinforcement plays a crucial role in overall stability [15]. Existing studies have extensively analysed geogrids under different soil and stress conditions. Geogrids, with their open grid structure, rely heavily on interlocking mechanisms, while geotextiles use surface friction and adhesion to achieve pullout resistance [16]. The particle size is pivotal in determining the geogrid and the soil interface friction. Geostraps, polymeric units with a flexible and ribbed profile, combine the benefits of both interlocking and friction, making them an innovative choice for geotechnical applications. Geostraps offer unique advantages over conventional geosynthetics due to their design and material properties. Their flexible nature allows for greater adaptability to soil deformations, reducing the risk of rupture or overstress in dynamic conditions. An anchored geostrap reinforcement installation in an unpaved road is shown in Figure 1. The testing site was situated on NH148B in Haryana, India. The ribbed surface of the geostrap enhances frictional interaction with the surrounding soil, potentially improving pullout resistance [17]. Figure 1: Installation of geostrap at subgrade level with anchorage on both sides. While geogrids have demonstrated excellent performance in various applications [18,19], certain limitations, such as deformation under high loads or inefficiency in fine-grained soils, highlight the need for alternative reinforcement solutions.