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Research on the failure behavior of cement- and fiber-reinforced sand under triaxial tensile loads

Hysen Ahmeti

Hysen Ahmeti

Faculty of Civil Engineering and Infrastructure, University for Business and TechnologyPrishtina, Kosovo
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Ahmeti, Hysen
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Ragip Behrami

Ragip Behrami

Faculty of Civil Engineering, Hasan Prishtina UniversityPrishtina, Republic of Kosovo
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Behrami, Ragip
  
Aug 14, 2025
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Article Category: Research Article
Published Online: Aug 14, 2025
Page range: 27 - 45
Received: Nov 12, 2024
Accepted: Apr 28, 2025
DOI: https://doi.org/10.2478/sgem-2025-0018
Keywords
© 2025 Hysen Ahmeti and Ragip Behrami, published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure 1

Gradation curve of the sand.
Gradation curve of the sand.

Figure 2

Split cylindrical mold.
Split cylindrical mold.

Figure 3

Specimen geometry.
Specimen geometry.

Figure 4

Schematic diagram of the triaxial tensile test device Tf (kPa).
Schematic diagram of the triaxial tensile test device Tf (kPa).

Figure 5

Triaxial tensile test device.
Triaxial tensile test device.

Figure 6

Fracture mode: (a) CP = 300 kPa, CC = 3.0%, and FC = 0.0%; (b) CP = 300 kPa, CC = 5.0%, and FC = 0.0%; (c) CP = 200 kPa, CC = 3.0%, and FT = TYPE I; (d) CP = 300 kPa, CC = 5.0%, and FT = TYPE II; (e) CP = 100 kPa, CC = 3.0%, and FT = TYPE II; and (f) CP = 200 kPa, CC = 5.0%, and FT = TYPE II.
Fracture mode: (a) CP = 300 kPa, CC = 3.0%, and FC = 0.0%; (b) CP = 300 kPa, CC = 5.0%, and FC = 0.0%; (c) CP = 200 kPa, CC = 3.0%, and FT = TYPE I; (d) CP = 300 kPa, CC = 5.0%, and FT = TYPE II; (e) CP = 100 kPa, CC = 3.0%, and FT = TYPE II; and (f) CP = 200 kPa, CC = 5.0%, and FT = TYPE II.

Figure 7

Stress–strain and volume change behavior with 3.0% cement: (a) FC = 0.0%; (b) FC = 0.5% and TF = I; and (c) FC = 0.5% and TF = II.
Stress–strain and volume change behavior with 3.0% cement: (a) FC = 0.0%; (b) FC = 0.5% and TF = I; and (c) FC = 0.5% and TF = II.

Figure 8

Stress–strain and volume change behavior with 5.0% cement: (a) FC = 0.0%; (b) FC = 0.5% and TF = I; (c) FC = 0.5% and TF = II.
Stress–strain and volume change behavior with 5.0% cement: (a) FC = 0.0%; (b) FC = 0.5% and TF = I; (c) FC = 0.5% and TF = II.

Figure 9

The effects of brittleness index versus confining pressure and type of fiber: (a) CC = 3.0% and (b) CC = 5.0%.
The effects of brittleness index versus confining pressure and type of fiber: (a) CC = 3.0% and (b) CC = 5.0%.

Figure 10

Changes in tensile strength against confining pressure and type of fiber: (a) CC = 3.0% and (b) CC = 5.0%.
Changes in tensile strength against confining pressure and type of fiber: (a) CC = 3.0% and (b) CC = 5.0%.

Figure 11

Axial strain changes in failure stress with changes in confining pressure and type of fiber: (a) CC = 3.0% and (b) CC = 5.0%.
Axial strain changes in failure stress with changes in confining pressure and type of fiber: (a) CC = 3.0% and (b) CC = 5.0%.

Figure 12

Changes in initial stiffness and stiffness at 50% tension strength of samples with 5% cement with changes in confining pressure and type of fiber.
Changes in initial stiffness and stiffness at 50% tension strength of samples with 5% cement with changes in confining pressure and type of fiber.

Figure 13

Changes in energy absorption up to failure point versus effects of fiber diameter.
Changes in energy absorption up to failure point versus effects of fiber diameter.

Figure 14

Changes in normalized absorbed energy compared to axial strain with the effect of fiber diameter.
Changes in normalized absorbed energy compared to axial strain with the effect of fiber diameter.

Figure 15

Failure envelopes for cement-treated sand reinforced with fibers compared to the percentage of cement: (a) CC = 3% and (b) CC = 5%.
Failure envelopes for cement-treated sand reinforced with fibers compared to the percentage of cement: (a) CC = 3% and (b) CC = 5%.

Figure 16

Changes in (a) the cohesion intercept and (b) internal friction coefficient compared to the fiber dimensional ratio.
Changes in (a) the cohesion intercept and (b) internal friction coefficient compared to the fiber dimensional ratio.

Figure 17

Changes in the main stress ratio in (a) peak stress and (b) residual stress.
Changes in the main stress ratio in (a) peak stress and (b) residual stress.

Summary of triaxial direct tension test results in the present study_

CC FC TF CPa Devatoric stress (kPa) Mean stress (kPa) Volumetric strain (%) Axial state (%)
At failure Residual state At failure Residual state At failure Residual state At failure Residual state
3 0 — 100 −196 −104 35 65 −0.037 −0.45 −0.41 −1.07
3 0 — 200 −277 −191 108 136 0.035 −0.86 −0.45 −1.32
3 0 — 300 −365 −278 178 207 0.029 −0.22 −0.49 −0.89
3 0 — 300 −364 −282 179 206 0.060 −0.10 −0.46 −0.73
3 0.5 I 100 −172 −160 43 47 −0.601 −1.61 −0.61 −0.51
3 0.5 I 200 −258 −240 114 120 −0.303 −1.21 −0.66 −2.18
3 0.5 I 300 −311 −293 196 202 −0.031 −1.35 −1.00 −3.26
3 0.5 I 200 −245 −222 118 126 −0.330 −1.45 −0.77 −2.33
3 0.5 — 100 −148 −123 51 59 −1.800 −1.80 −1.40 −4.50
3 0.5 — 200 −239 −192 120 136 −1.050 −1.43 −2.06 −4.39
3 0.5 — 300 −320 −292 193 203 −1.190 −1.60 −2.51 −1.76
5 0 — 100 −211 −95 30 68 −0.229 −0. 66 −0.58 −1.01
5 0 — 200 −346 −164 85 145 −0.100 −0.63 −0.44 −1.25
5 0 — 300 −431 −240 156 220 −0.050 −0.53 −0.56 1.46
5 0 — 200 −316 −172 95 143 −0.090 −0.43 −0.42 −1.22
5 0 — 300 −450 −232 150 223 −0.050 −0.33 −0.56 −1.47
5 0.5 I 100 −186 −165 38 45 0.110 −1.62 −0.55 −3.02
5 0.5 I 200 −333 −313 89 96 0.120 −0.99 −0.38 −3.03
5 0.5 I 300 −406 −369 165 177 0.110 −1.06 −0.70 −5.54
5 0.5 II 100 −191 −157 36 48 −2.160 −2.68 −0.68 −9.97
5 0.5 II 200 −299 −267 100 111 −1.860 −2.00 −05.86 −11.56
5 0.5 II 300 −364 −328 179 191 −0.900 −1.80 −8.89 −12.09
5 0.5 II 200 −322 −256 93 115 −2.150 −3.10 −4.77 −7.20

Physical properties of the fiber_

Typing Fiber type I Fiber type II
Material Micro-synthetic Macro-synthetic
Tensile strength 4,000,000 570,000–660,000 kPa
Diameter 23 μm 300 μm
Aspect ratio 600–1,200 30–120
Number per kg <100,000,000 53,800
Color Glossy Gray

Summary of uniaxial tensile strength test results in the present study_

CCa FCb TFc T f (kPa)
3 0 — 44
3 0.5 I 41
3 0.5 II 39
5 0 — 104
5 0.5 I 95
5 0.5 II 90

Physical properties of the cement object_

Object Range
Autoclave 0.2
Blian
Setting time (min)
Initial 120
Final 180
Compressive strength (MPa)
3 days 220
7 days 320
28 days 400
Language:
English
Publication timeframe:
4 times per year
Journal Subjects:
Geosciences, Geosciences, other, Materials Sciences, Composites, Porous Materials, Physics, Mechanics and Fluid Dynamics
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