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Geomechanics and Engineering
  Volume 25, Number 3, May10 2021, pages 207-219

Shear wave velocity of fiber reinforced cemented Toyoura silty sand
Muhammad Safdar, Tim Newson, Colin Schmidt, Kenichi Sato, Takuro Fujikawa and Faheem Shah

    Several additives are used to enhance the geotechnical properties (e.g., shear wave velocity, shear modulus) of soils to provide sustainable, economical and eco-friendly solutions in geotechnical and geo-environmental engineering. In this study, piezoelectric ring actuators are used to measure the shear wave velocity of unreinforced, fiber, cemented, and fiber reinforced cemented Toyoura sand. One dimensional oedometer tests are performed on medium dense specimens of Toyoura sand-cement-fiber-silica flour mixtures with different percentages of silica flour (0-42%), fiber and cement (e.g., 0-3%) additives. The experimental results indicate that behavior of the mixtures is significantly affected by the concentration of silica flour, fiber and cement additives. Results show that with the addition of 1-3% of PVA fibers, the shear wave velocity increases by only 1-3%. However, the addition of 1-4% of cement increases the shear wave velocity by 8-35%. 10.5-21% increase of silica flour reduces the shear wave velocity by 2-5% but adding 28-42% silica flour significantly reduces the shear wave velocity by 12-31%. In addition, the combined effect of cement and fibers was also found and with only 2% cement and 1% fiber, the shear wave velocity increase was found to be approximately 24% and with only 3% cement and 3% fibers this increased to 35%. The results from this study for the normalized shear modulus and normalized mean effective stress agree well with previous findings on pure Toyoura sand, Toyoura silty sand, fiber reinforced, fiber reinforced cemented Toyoura sand. Any variations are likely due to the difference in stress history (i.e., isotropic versus anisotropic consolidation) and the measurement method. In addition, these small discrepancies could be attributed to several other factors. The potential factors include the difference in specimen sizes, test devices, methods of analysis for the measurement of arrival time, the use of an appropriate Ko to convert the vertical stresses into mean effective stress, and sample preparation techniques. Lastly, it was investigated that there is a robust inverse relationship between α factor and β_0 exponent. It was found that less compressible soils exhibit higher α factors and lower β_0 exponents.
Key Words
    shear wave velocity; piezoelectric ring actuators; ground improvement; ground remediation; sustainability; oedometer tests
Muhammad Safdar and Faheem Shah: Earthquake Engineering Center, Department of Civil Engineering, University of Engineering and Technology, Peshawar, Pakistan

Tim Newson: Department of Civil and Environmental Engineering, Western University, London, Ontario, Canada

Colin Schmidt: Thurber Engineering Ltd. Calgary, Alberta, Canada

Kenichi Sato and Takuro Fujikawa: Department of Civil Engineering, Fukuoka University, Nanakuma, Jonan, Fukuoka, Japan

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