The increasing production of waste glass fiber reinforced polymer (GFRP) is causing severe environmental pollution, highlighting the need for an effective treatment method. This study explores recycling waste GFRP powder to substitute ground granulated blast furnace slag (GGBS) in synthesizing geopolymers, aiming to rapidly stabilize clayey soil. The impact of GFRP powder replacement, alkali solution concentration, alkaline activator/precursor (A/P) ratio, and binder content on the geomechanical properties and permeability of stabilized soil was thoroughly examined. The findings revealed that replacing GFRP powder from 20 wt% to 40 wt% lowered the unconfined compressive strength (UCS). However, soil stabilized with 30 wt% GFRP powder displayed the highest shear strength. This indicates that the incorporation of an appropriate amount of GFRP powder elevates clay cohesion. Furthermore, an increase in GFRP powder replacement improved permeability coefficient in the early stages, with minimal impact observed after 28 days. Scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) analysis revealed a microstructural evolution of the stabilized soil, transitioning from a porous to a denser, more homogeneous composition over the curing period, which can be attributed to the formation of cluster gels enveloping the soil particles. Life cycle assessment (LCA) analysis indicated that the GFRP powder/GGBS geopolymer presents an alternative option to traditional Ordinary Portland Cement (OPC) binder, featuring a global warming potential (GWP)/strength ratio reduction of 6 %-40 %. This research offers a practical solution for effectively utilizing GFRP waste in a sustainable manner, with minimal energy consumption and pollution, thereby contributing to the sustainable development of soil stabilization.

In response to escalating environmental concerns, this study explored the use of sisal fiber as a sustainable alternative to traditional cement or synthetic fibers for soft soil stabilization. An optimal selection test was conducted to determine the optimal sisal fiber characteristics and their impact on the mechanical performance of cemented soil. The findings indicated that incorporating sisal fibers into cemented soil inhibits crack propagation, thereby enhancing its strength and ductility. A significant improvement was achieved by incorporating optimal fiber parameters (content = 0.4 %, length = 11 mm) into the cemented-soil, the compressive strength reached 4.4 MPa (by 29.4 %). In addition, to further improve the work performance of sisal fibercemented soil (SFCS), alkaline and acetylation treatments were applied, respectively, to prevent volume instability and degradation of sisal fiber. The study also evaluated the effects of these modification methods on the physical properties of sisal fiber and the strength of sisal fibercemented soil (SFCS). The results showed that a 6 % NaOH treatment was determined to be the most effective modification method, reducing the moisture affinity of sisal fiber, improving fiber-matrix bonding, and consequently enhancing the mechanical properties of SFCS (by 18.7 %). However, it should be noted that an excessively high concentration may adversely affect fiber properties, negatively impacting the strength of SFCS (by up to 11.59 %).

Recent research has focused on reinforcing sand consolidated through microbial -induced carbonate precipitation (MICP) with alkali -treated fibers to enhance its mechanical properties and mitigate brittleness. This research investigated how modified fiber affected the microstructure and properties of MICP solid sand. The fiber content (0, 0.5, 1, 3, and 5%), pretreatment concentration (0, 1, 5, 10, and 20%), pretreatment time (0, 0.5, 1, 2, and 4 h), and pretreatment temperature (25, 35, 45, and 55 degrees C) required for the experiment were determined by MICP testing. The interactions between fiber, sand, and calcium carbonate(CaCO3) were analyzed by calcium carbonate content(CaCO3(%)), unconfined compressive strength (UCS), environmental scanning electron microscopy (ESEM), and X-ray diffraction (XRD). The specimen without added fiber had a UCS of 2.13 MPa, the UCS of the added fiber sample was 2.8 MPa, which was 31.46% more than that of the specimen without added fiber, and the UCS of the specimen with added alkali -treated fiber was 3.62 MPa, which was 70% more than that of the specimen without added fiber and 28.57% more than that of the added untreated fiber. The optimum content of jute fibers was 0.5%, and the optimum concentration of alkali treatment of jute fibers was 10% for one hour.

Shotcrete plays a pivotal role in the construction of tunnels and underground structures; however, its inherent brittleness necessitates reinforcement to enhance ductility. This research explores the use of fiber-reinforced shotcrete as primary tunnel support to enhance ductility and reduce brittleness. Traditional steel mesh reinforcement complexities have led to the investigation of alternative materials. The research evaluates different fiber mix designs, including industrial steel, recycled steel fibers from tires, and Forta fibers, examining their strength parameters and deformation performance. A 3D finite element model is used to simulate a horseshoeshaped tunnel with optimal mix design and plain shotcrete in a soil environment. The study finds that hybrid industrial and recycled fibers are more effective than single fibers, enhancing compressive, tensile, and flexural strength and reducing ground surface settlement and tensile damage. The optimal mix design of this study has increased compressive, tensile, and flexural strength, as well as flexural toughness, compared to plain shotcrete. Numerical modeling reveals that utilizing fiber reinforced shotcrete made out of optimal fiber mix design as primary support results in a significant reduction in ground surface settlement and tensile damage value. Furthermore, the study shows a significant reduction in the damaged zone area under tensile stresses. The results of the study highlight the potential of fiber reinforced shotcrete as a primary support for tunnels, leading to improved performance and sustainability in tunnel construction.

Coal-bearing soil slopes are associated with a high risk of landslides when subjected to high soil water content. Steel bars have been used as soil nailing for slope stabilization; however, corrosion may occur in an aggressive environment. Glass fiber reinforced polymer (GFRP) and basalt fiber reinforced polymer (BFRP) bars have higher resistance to corrosion and could be alternatives to steel bars, but their elastic modulus and bonding strength with cement concrete are inferior to steel bars, which may result in lower reinforcement effects against landslides and hence require further investigation. In this study, the mechanical properties of different types of bars were investigated using tensile tests. The mineral composition of the soil samples was analyzed. Subsequently, pull-out tests were conducted on three types of bars (steel, GFRP, and BFRP) embedded in grouts in the soil. Up to 38 test scenarios were investigated, and the results were statistically analyzed using an analysis of variance test. The effects of several factors were studied, including the bar type, water content, soil compaction degree, and soil surcharge. The results showed that the bar type had an insignificant effect on the maximum pull-out loads, indicating the feasibility of using GFRP and BFRP bars as alternatives to steel bars for soil nailing in coal-bearing soil slopes. The reinforcement effect can be weakened by rainfall or drought events and enhanced by higher compaction energy and surcharge loads.

对玻璃纤维(glass fiber reinforced polymer, GFRP)筋和GFRP–钢筋夹芯复合筋在盐湖地区多重环境因素耦合作用下进行耐久性试验,分析环境类型及作用时间对极限抗拉强度、弹性模量、极限应变的影响。结果表明:在多重因素耦合作用下,随着盐湖卤水腐蚀周期、冻融次数、干湿循环次数的增加,GFRP筋和GFRP夹芯复合筋的抗拉强度逐渐减小,但是GFRP筋减小的幅度较小,而GFRP夹芯复合筋由于有钢筋的存在,抗拉强度减小比较大,特别是在盐湖卤水90 d以上、冻融150次以上时GFRP夹芯复合筋的极限抗拉强度实验不是很明显,屈服强度几乎不存在并且与抗拉极限强度相接近,表现出明显的脆性;在各种因素作用下,GFRP筋随着龄期的增加,弹性模量先减少后增加,而GFRP夹芯复合筋的弹性模量逐渐减小,相对来讲减小的幅度不是很大;各种耦合因素作用下GFRP筋和GFRP夹芯复合筋的极限抗拉强度、弹性模量均比单因素作用下小,且腐蚀性的大小关系是盐湖卤水+干湿循环+冻融耦合>盐湖卤水+干湿循环>冻融>盐湖卤水。

对玻璃纤维(glass fiber reinforced polymer, GFRP)筋和GFRP–钢筋夹芯复合筋在盐湖地区多重环境因素耦合作用下进行耐久性试验,分析环境类型及作用时间对极限抗拉强度、弹性模量、极限应变的影响。结果表明:在多重因素耦合作用下,随着盐湖卤水腐蚀周期、冻融次数、干湿循环次数的增加,GFRP筋和GFRP夹芯复合筋的抗拉强度逐渐减小,但是GFRP筋减小的幅度较小,而GFRP夹芯复合筋由于有钢筋的存在,抗拉强度减小比较大,特别是在盐湖卤水90 d以上、冻融150次以上时GFRP夹芯复合筋的极限抗拉强度实验不是很明显,屈服强度几乎不存在并且与抗拉极限强度相接近,表现出明显的脆性;在各种因素作用下,GFRP筋随着龄期的增加,弹性模量先减少后增加,而GFRP夹芯复合筋的弹性模量逐渐减小,相对来讲减小的幅度不是很大;各种耦合因素作用下GFRP筋和GFRP夹芯复合筋的极限抗拉强度、弹性模量均比单因素作用下小,且腐蚀性的大小关系是盐湖卤水+干湿循环+冻融耦合>盐湖卤水+干湿循环>冻融>盐湖卤水。