Geotechnical properties of coarse-fine mixtures and their interaction with geogrids through large direct shear testing

Ekici, Anıl
Different proportions of gravel, sand, nonplastic silt, kaolin, and bentonite were mixed to obtain ten coarse-fine mixtures (CFM) having 0%, 12%, 20%, 30%, 40% fines content (FC) and 5% and 15% plasticity indices (PI). Mixtures were evaluated to identify behavioral thresholds and address backfill restrictions in commonly used guidelines to design reinforced earth walls. All CFM specimens were initially compacted to 95% of standard Proctor dry density at optimum moisture content. Index, hydraulic properties, and specific surface areas were investigated. FC=15% for PI=5% and FC=12% for PI=15% represented the transition between fine and coarse-grain domination according to particle packing. Unconfined compressive strength, CU triaxial, and large-scale compression tests were conducted. FC=20% was the transitional boundary for CFM with PI=5%, reflected in shifting of the dilation tendency to contraction, while samples having PI=15% mainly had relatively high initial contraction followed by dilation. Consolidation data in triaxial tests indicated that FC of 30% to 40% for PI=15% was the transition at which normally-consolidated clay-like behavior began. Strength of CFM and interaction with geogrids (with and without drainage property) were investigated through large direct shear tests (300x300 mm) under 55, 105, and 155 kPa normal stresses. Interface shear strength coefficients ranged between 0.65- 1.05. Bond efficiencies increased with normal stress and decreased with PI. Geogrid’s drainage component did not affect the interface strength for unsaturated specimens. In saturated mixtures, drainage was more critical for FC=40% than FC=20%, as strength reductions due to excess pore pressures were significant, especially for FC=40% and PI=15%.


Effects of Fines Content and Plasticity on Index Properties and Hydraulic Conductivity of Coarse-Fine Mixtures
Ekici, Anıl; Huvaj Sarıhan, Nejan; Akgüner, Cem (2022-02-01)
Ten coarse-fine mixtures (CFM) (intermediate soils) having fines contents (FC) of 0%, 12%, 20%, 30%, 40%, and plasticity indices (PI) of 5% and 15% were prepared in the laboratory by mixing different fractions of gravel, sand, nonplastic silt, kaolin, and bentonite. Index properties, volume change during saturation, specific surface area (SSA), and saturated hydraulic conductivity of CFM were investigated. For compacted CFM, aFC=15%" role="presentation" style="box-sizing: border-box; display: inline; font-s...
Dry grinding kinetics of binary mixtures of ceramic raw materials by Bond milling
Ipek, H; Ucbas, Y; Yekeler, M; Hoşten, Çetin (Elsevier BV, 2005-01-01)
The kinetics of batch dry grinding of binary mixtures of ceramic raw materials, namely quartz-kaolin, quartz-potassium feldspar and kaolin-potassium feldspar, from the feed sizes of -3.350 + 2.360, -2.000 + 1.400, -0.850 + 0.600, -0.500 + 0.355 and -0.300 + 0.212 mm have been determined using a Bond mill with a mixture of ball sizes of 38.10, 31.75, 25.40, 19.05 and 12.70 mm diameter and total mass of 22.648 kg. The Bond mill used was a size of 30.5 cm diameter, 30.5 cm length, with a total volume of 22,272...
Quantification of CaCO3-CaSO3 center dot 0.5H(2)O-CaSO4 center dot 2H(2)O mixtures by FTIR analysis and its ANN model
Boke, H; Akkurt, S; Ozdemir, S; Gokturk, EH; Saltık, Emine Nevin (2004-02-01)
A new quantitative analysis method for mixtures of calcium carbonate (CaCO3), calcium sulphite hemihydrate (CaSO3.1/2H(2)O) and gypsum (CaSO4.2H(2)O) by FTIR spectroscopy is developed. The method involves the FTIR analysis of powder mixtures of several compositions on KBr disc specimens. Intensities of the resulting absorbance peaks for CaCO3, CaSO3.1/2H(2)O and CaSO4.2H(2)O at 1453, 980, 1146 cm(-1) were used as input data for an artificial neural network (ANN) model, the output being the weight percent co...
Porosity and Permeability Determinations in Sandstone and Limestone Rocks Using Thin Section Analysis Approach
Iscan, A. G.; Kök, Mustafa Verşan (2009-01-01)
In this study, porosity and permeability values of six different rock samples (three limestone and three sandstone) were determined using thin section analysis technique. The parameters were determined by applying capillary pressure approach through digitally scanned microscopic images. The existence of steam and liquid water in the reservoir make the capillary pressure approach more accurate for the determination of rock properties. The geothermal gradient may also participate in this approach, since the p...
Geotechnical evaluation of Ankara clay as a compacted clay liner
Met, Ilker; Akgün, Haluk (2015-08-01)
This study investigates the geotechnical properties, and mineralogical and permeability characteristics of "Ankara clay" to evaluate its suitability as a compacted clay landfill liner material. The geotechnical index properties of the clayey soil samples collected from the western part of Ankara were determined. All the soil samples were tested for permeability by means of falling head compaction permeameter apparatus. The mineralogy of the soil samples were examined by X-ray diffraction and scanning electr...
Citation Formats
A. Ekici, “Geotechnical properties of coarse-fine mixtures and their interaction with geogrids through large direct shear testing,” Ph.D. - Doctoral Program, Middle East Technical University, 2022.