Experimental Determination of Shear Strength Properties of Lightweight Expanded Clay Aggregates Using Direct Shear and Triaxial Tests

Authors: Mahsa Shafaei Bajestani, Mahmoud Yazdani, Aliakbar Golshani

Abstract:

Artificial lightweight aggregates have a wide range of applications in industry and engineering. Nowadays, the usage of this material in geotechnical activities, especially as backfill in retaining walls has been growing due to the specific characteristics which make it a competent alternative to the conventional geotechnical materials. In practice, a material with lower weight but higher shear strength parameters would be ideal as backfill behind retaining walls because of the important roles that these parameters play in decreasing the overall active lateral earth pressure. In this study, two types of Light Expanded Clay Aggregates (LECA) produced in the Leca factory are investigated. LECA is made in a rotary kiln by heating natural clay at different temperatures up to 1200 °C making quasi-spherical aggregates with different sizes ranged from 0 to 25 mm. The loose bulk density of these aggregates is between 300 and 700 kN/m³. The purpose of this research is to determine the stress-strain behavior, shear strength parameters, and the energy absorption of LECA materials. Direct shear tests were conducted at five normal stresses of 25, 50, 75, 100, and 200 kPa. In addition, conventional triaxial compression tests were operated at confining pressures of 50, 100, and 200 kPa to examine stress-strain behavior. The experimental results show a high internal angle of friction and even a considerable amount of nominal cohesion despite the granular structure of LECA. These desirable properties along with the intrinsic low density of these aggregates make LECA as a very proper material in geotechnical applications. Furthermore, the results demonstrate that lightweight aggregates may have high energy absorption that is excellent alternative material in seismic isolations.

Keywords: Expanded clay, direct shear test, triaxial test, shear properties, energy absorption.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1315861

References:

[1] Arioz, O., et al. "A preliminary research on the properties of lightweight expanded clay aggregate." Journal of the Australian Ceramic Society 44.1 (2008): 23.
[2] Stoll, R. D., and Holm, T. A. (1985). “Expanded shale lightweight fill: Geotechnical properties.” Journal of Geotechnical Engineering 111, no.8, 1023–1027.
[3] Valsangkar, A. J., and Holm, T. A. (1990). “Geotechnical properties of expanded shale lightweight aggregate.” Geotech. Test. J., 13(1), 10– 15.
[4] Saride, S., Puppala, A. J., Williammee, R., & Sirigiripet, S. K. (2009). “Use of lightweight ECS as a fill material to control approach embankment settlements.” Journal of Materials in Civil Engineering, 22(6), 607-617.
[5] Puppala, Anand J., et al. "Long-Term Performance of a Highway Embankment Built with Lightweight Aggregates." Journal of Performance of Constructed Facilities 31.5 (2017): 04017042.
[6] Laine, Leo. "Numerical Simulation of Ground Shock Attenuation Layer for Swedish Rescue Centers and Shelters." Proceedings of the 4th Asia Pacific Conference on Shock and Impact Loads on Structures. 2001.
[7] Ardakani, Alireza, and Mahmoud Yazdani. "The relation between particle density and static elastic moduli of lightweight expanded clay aggregates." Applied Clay Science 93 (2014): 28-34.
[8] ANSI, B. "ASTM D698-Test Methods for Moisture-Density Relations of Soils and Soil-Aggregate Mixtures." Method A (Standard Proctor). ASTM D854.
[9] ASTM, D3080. "3080–03 (2003) Standard Test Method for Direct Shear Test of Soils Under Consolidated Drained Conditions." Annual Book of ASTM Standards, ASTM.EN 15732.
[10] Standard, A. S. T. M. "D7181-11 (2011)." Method for Consolidated Drained Triaxial Compression Test for Soils 1: 1-11.
[11] Olson, Roy E., Lai Jiunnren, (2004). “Direct shear testing.” Advanced Geotechnical Laboratory, Department of Construction Engineering Chaoyang University of Technology.
[12] Medzvieckas, Jurgis, Neringa Dirgėlienė, and Šarūnas Skuodis. "Stress-strain States Differences in Specimens during Triaxial Compression and Direct Shear Tests." Procedia Engineering 172 (2017): 739-745.
[13] Hamidi, Amir, and Mahdi Hooresfand. "Effect of fiber reinforcement on triaxial shear behavior of cement treated sand." Geotextiles and Geomembranes 36 (2013): 1-9.