scholarly journals Direct Shear Creep Characteristics and Microstructure of Fiber-Reinforced Soil

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Hao Tang ◽  
Huahua Li ◽  
Zhao Duan ◽  
Chiyang Liu ◽  
Guannan Wu ◽  
...  

Fiber-reinforced soil is an excellent engineering material that has become a focus of research. Most studies focus on the conventional mechanical properties of reinforced soil, such as its tensile, compressive, and shear strength, and rarely study its creep-related mechanical properties. However, when such soil is used as backfill, the creep effect should not be ignored. This study explored the characteristics of creep mechanics in reinforced soil, the fiber-reinforcement mechanism, and the dynamics of microstructures before and after creep tests. Direct shear creep tests were carried out using a direct shear creep tester on soil reinforced with natural palm fibers of equal length (1.5 cm) in different amounts (0%, 0.2%, 0.6%, 1.0%). Microscale tests were carried out on the reinforced soil samples before and after the creep tests by polarized light and scanning electron microscopy. The results show that the fiber reinforcement can restrain the deformation and enhance the long-term strength of soil. However, a nonlinear relationship between the reinforcement effect and fiber content was found, with 0.6% being the optimal content. Palm fibers have rough surfaces, grooves, and independent pore chambers, which increase the effective contact area and interaction with the soil. With increases in fiber content, the fibers interweave to form a nestled network structure, which increases the strength and integrity of the soil. Fiber addition changes the microstructure of the soil pores; the proportion of large pores decreases and that of small pores increases. Under the effect of creep, the pore changes follow the principle of pore homogenization; large pores are destroyed and transformed into small pores, causing the porosity of reinforced soil to decrease faster and be less porous than unreinforced soil. This research can provide technical reference for the engineering application of palm fiber-reinforced soil.

2020 ◽  
Vol 10 (24) ◽  
pp. 9043
Author(s):  
Yingying Zhao ◽  
Xianzhang Ling ◽  
Weigong Gong ◽  
Peng Li ◽  
Guoyu Li ◽  
...  

To study the mechanical properties of Y-shaped polypropylene fiber-reinforced subgrade fill, the strength characteristics of fiber-reinforced soil with different fiber contents, fiber lengths, and confining pressures were investigated through triaxial compression tests. The test results showed that fiber reinforcement significantly improved the strength and cohesion of the subgrade fill but had a limited impact on the internal friction angle. The fiber-reinforced soil specimens exhibited a failure pattern of bulging deformation, showing plastic failure characteristics. As the fiber content and length increased, the strength of the fiber-reinforced soil increased and then decreased. The optimal fiber content was 0.2%, and the optimal fiber length was between 12 and 18 mm in all test conditions. The strength of the fiber-reinforced soil increased with increasing confining pressure. An empirical model for predicting the failure strength of fiber-reinforced soil was established by analyzing the relationships between the failure strength of the fiber-reinforced soil and the fiber content, fiber length, and confining pressure. The stress-strain relationship of the fiber-reinforced soil exhibited strain-hardening characteristics and could be approximated by a hyperbolic curve. The Duncan-Chang model could be used to describe the stress-strain relationship of this fiber-reinforced soil. A calculation method to determine the model parameters (initial tangent modulus and ultimate deviator stress) was proposed.


2019 ◽  
Vol 168 ◽  
pp. 291-301 ◽  
Author(s):  
Shamsad Ahmad ◽  
Mehboob Rasul ◽  
Saheed Kolawole Adekunle ◽  
Salah U. Al-Dulaijan ◽  
Mohammed Maslehuddin ◽  
...  

Author(s):  
Nilo C. Consoli ◽  
Michéle D. T. Casagrande ◽  
Pedro D. M. Prietto ◽  
Anto⁁nio Thomé

2019 ◽  
Vol 15 (5) ◽  
pp. 947-957 ◽  
Author(s):  
Giridharan R. ◽  
Raatan V.S. ◽  
Jenarthanan M.P.

Purpose The purpose of this paper is to study the effects of fiber length and content on properties of E-glass and bamboo fiber reinforced epoxy resin matrices. Experiments are carried out as per ASTM standards to find the mechanical properties. Further, fractured surface of the specimen is subjected to morphological study. Design/methodology/approach Composite samples were prepared according to ASTM standards and were subjected to tensile and flexural loads. The fractured surfaces of the specimens were examined directly under scanning electron microscope. Findings From the experiment, it was found that the main factors that influence the properties of composite are fiber length and content. The optimum fiber length and weight ratio are 15 mm and 16 percent, respectively, for bamboo fiber/epoxy composite. Hence, the prediction of optimum fiber length and content becomes important, so that composite can be prepared with best mechanical properties. The investigation revealed the suitability of bamboo fiber as an effective reinforcement in epoxy matrix. Practical implications As bamboo fibers are biodegradable, recyclable, light weight and so on, their applications are numerous. They are widely used in automotive components, aerospace parts, sporting goods and building industry. With this scenario, the obtained result of bamboo fiber reinforced composites is not ignorable and could be of potential use, since it leads to harnessing of available natural fibers and their composites rather than synthetic fibers. Originality/value This work enlists the effect of fiber length and fiber content on tensile and flexural properties of bamboo fiber/epoxy composite, which has not been attempted so far.


2020 ◽  
Vol 26 (3) ◽  
pp. 295-299
Author(s):  
Sekar SANJEEVI ◽  
Athijayamani AYYANAR ◽  
Ramanathan KALIMUTHU ◽  
Sidhardhan SUSAIYAPPAN

In this paper, the effects of three different chemical treatments on the mechanical properties of Phenol Formaldehyde (PF) composites reinforced with the Calotropis Gigantea Fibers (CGFs) were investigated based on the fiber content of the fibers. Composites were prepared by the untreated and treated fibers using the hand lay up technique and their mechanical properties were evaluated and compared. The results revealed that the composites show the greater mechanical properties at 40 wt.% for the untreated condition. Composites prepared with alkali treated fibers show the better mechanical properties as compared with the other treated fiber composites.


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