Effect of fiber reinforcement on shear strength and void ratio of soft clay

Abstract

In this study, a series of multi-stage drained reverse direct shear tests were carried out on soft clay samples reinforced with 0.25% and 0.50% polypropylene fibers of 6 mm, 10 mm and 19 mm in length. Tests were carried out at different normal effective stresses and cumulative horizontal shear displacement of 1.17 times of the sample width. Results showed an increase of the shear strength with the increase of fiber content and length. However, the rate of improvement was capped with the normal effective stress applied during the shearing stage. At a high normal effective stress, the shear strength of the fiber-reinforced soft clay approached that of the unreinforced clay regardless of the amount of fiber inclusion. The rate of shear strength improvement decayed with the number of shear cycles. Fiber reinforcement also resulted in a reduction of the compressibility of the soft clay at consecutive consolidation and shear stages. Although the effective internal friction angle of the soft clay was not altered significantly with the fiber reinforcement, the effective cohesion of the soft clay improved significantly as much as 6.4 and 8.5 times with the inclusion of 0.25% and 0.50% of 10 mm long fibers, respectively.

Engineering properties of plastic waste reinforced sand

“…Also, for PP waste fiber-reinforced sand at 1% usage, the peak strength was reached to 1614 kPa (about 7 times of the unreinforced one) at the same confining pressure. A similar trend was observed in previous works [4,[12][13]20]. As the plastic waste reinforced sand was subjected to deformation, friction which is appeared between soil and plastic wastes led to development of tensile stress in the plastic wastes, also increase in confinement of the sample, and consequently increase in the shear strength of the samples.…”

“…Actually, the value of increase in peak shear stress for the sand reinforced with 15 mm length PET fibers is almost the same as that for the sand reinforced with 10 mm length fibers with a negligible difference. Previous research has also indicated a similar trend between the shear strength improvement of fiber-reinforced soil and the length of the fiber [4]. This phenomenon can be attributed to the following reasons:…”

“…First, the discrete fibers are simply added and mixed randomly with soil, in much the same way as cement, lime, or other additives. Second, randomly distributed fibers limit potential planes of weakness that can develop parallel to oriented reinforcement [1][2][3][4].…”

“…Using plastic wastes such as tire shreds to improve the mechanical properties of soil dates back to the 1990. Many researchers studied on the engineering properties of plastic waste reinforced soils [2,4,[6][7][8][9][10][11][12][13][14][15][16][17][18]. The idea of incorporating other plastic wastes in soil was first proposed by Benson and Khire [19].…”

The Mechanical and Microstructural Properties of Composite Structures Made of a Cement-Tailing Backfill and Rock Core

“…Meanwhile, many scientific research developments have been achieved in backfill mining technology, backfill materials, and the mechanical properties of backfills [6][7][8][9][10][11]. For example, Mirzababaei et al [12][13][14] studied the behavior of soft clay reinforced with short fibers, and found sand ratio of the backfill body, the changing range of the average infrared radiation temperature (AIRT) of the backfill body became increasingly smaller [26][27][28]. Cai et al found that the strength of pillars or rock masses surrounded by backfill material can increase [29,30].…”