Influence of feedstock type and particle size on efficiency of biochar in improving tensile crack resistance and shear strength in lean clayey soil

2021 ◽  
Vol 30 (4) ◽  
pp. 646-661
Author(s):  
Himanshu Kumar ◽  
Shan Huang ◽  
Guoxiong Mei ◽  
Ankit Garg
Keyword(s):  
Particle Size ◽  
Green Infrastructure ◽  
Clayey Soil ◽  
Friction Angle ◽  
Pig Manure ◽  
Landfill Liners ◽  
Fine Grained ◽  
Landfill Cover ◽  
Sharp Edges ◽  
Cover Material

The development of tensile stress can cause desiccation cracks, further increasing infiltration and inducing instability in green infrastructure (slopes and landfill liners). Recent research has promoted the use of biochar (i.e., stable carbon with a life period of more than 500 years) as an eco-friendly material that can provide simultaneous benefits in reducing tensile stresses and crack development, aiming to enhance landfill cover longevity. However, there is a lack of guidelines and criteria for selecting biochar (feedstock type and particle size) as landfill cover material. This study aims to investigate the effects of biochar particle size and feedstock type on cracking of soil. Two contrasting feedstock types (i.e., pig manure-based and wood-based) have been selected for amendment on lean clay soil. Laboratory experiments were conducted to monitor the cracks. The results show that wood biochar (WB) is more efficient in crack reduction than pig manure biochar (PMB). Moreover, it has been observed that fine-grained biochar is more suspectable to cracks formation regardless of biochar type. The cohesion and internal friction angle of biochar are dependent on the surface morphology of biochar. WB has more angularity and sharp edges, which can increase interlocking in soil, thereby enhancing shear resistance and, hence, soil stability. The comprehensive study can help narrow down the selectivity of biochar and its specifications to mitigate cracks and enhance the strength of landfill cover.

scholarly journals Influence of Structural Plane Microscopic Parameters on Direct Shear Strength

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Yanhui Cheng ◽  
Weijun Yang ◽  
Dongliang He
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Internal Friction ◽  
Direct Shear Test ◽  
Shear Test ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Direct Shear ◽  
Stiffness Ratio ◽  
Structural Plane

Structural plane is a key factor in controlling the stability of rock mass engineering. To study the influence of structural plane microscopic parameters on direct shear strength, this paper established the direct shear mechanical model of the structural plane by using the discrete element code PFC2D. From the mesoscopic perspective, the research on the direct shear test for structural plane has been conducted. The bonding strength and friction coefficient of the structural plane are investigated, and the effect of mesoscopic parameters on the shear mechanical behavior of the structural plane has been analyzed. The results show that the internal friction angle φ of the structural plane decreases with the increase of particle contact stiffness ratio. However, the change range of cohesion is small. The internal friction angle decreases first and then increases with the increase of parallel bond stiffness ratio. The influence of particle contact modulus EC on cohesion c is relatively small. The internal friction angle obtained by the direct shear test is larger than that obtained by the triaxial compression test. Parallel bond elastic modulus has a stronger impact on friction angle φ than that on cohesion c. Under the same normal stress conditions, the shear strength of the specimens increases with particle size. The shear strength of the specimen gradually decreases with the increase of the particle size ratio.

scholarly journals Geotechnical Evaluation of Diesel Contaminated Clayey Soil

2021 ◽  
Vol 11 (14) ◽  
pp. 6451
Author(s):  
Christian E. Hernández-Mendoza ◽  
Pamela García Ramírez ◽  
Omar Chávez Alegría
Keyword(s):  
Contaminated Soils ◽  
Clayey Soil ◽  
Friction Angle ◽  
Geotechnical Properties ◽  
Natural Soil ◽  
Osmotic Suction ◽  
The One ◽  
Available Information ◽  
The Impact ◽  
Diesel Contamination

Soil contamination by different hydrocarbons has rapidly expanded worldwide, surpassing the self-purification capacity of soils and increasing the number of contaminated sites. Although much effort has been devoted to study the effects of diesel contamination on the geotechnical properties of soil, there is still limited available information about it. Moreover, there is no available information about the maximum diesel retention that soil can have and its effect on the geotechnical behavior of the soil. Thus, in this paper, we determined the maximum diesel retention by an unsaturated clayey soil and evaluated the impact of diesel contamination on its geotechnical properties. The results showed that the soil could only retain 12.6% of the added diesel and the excess was expulsed. At such a diesel concentration, the saturation rate of the soil was lower than 80%. Diesel contamination increased the plasticity and the internal friction angle of the soil, while its cohesion was considerably decreased. It should be noted that the matric suction of contaminated soil was lower than the one obtained for natural soil. However, its osmotic suction was considerably higher. This indicates that osmotic suction must be considered to evaluate the shear strength of contaminated soils.

Reuse of MSWI bottom ash mixed with natural sodium bentonite as landfill cover material

2013 ◽  
Vol 31 (6) ◽  
pp. 577-584 ◽  
Author(s):  
Sara Puma ◽  
Franco Marchese ◽  
Andrea Dominijanni ◽  
Mario Manassero
Keyword(s):  
Bottom Ash ◽  
Sodium Bentonite ◽  
Landfill Cover ◽  
Mswi Bottom Ash ◽  
Cover Material

scholarly journals The effect of liquid pig manure on the wheat yield, content and balance of nutrients in light-gray forest soil with light particle-size composition

2019 ◽  
Vol 20 (5) ◽  
pp. 456-466
Author(s):  
V. I. Titova ◽  
L. D. Varlamova ◽  
R. N. Rybin ◽  
T. V. Andronova
Keyword(s):  
Particle Size ◽  
Spring Wheat ◽  
Wheat Yield ◽  
Size Composition ◽  
Light Particle ◽  
Pig Manure ◽  
Wheat Crop ◽  
Dry Matter Content ◽  
Particle Size Composition ◽  
Positive Balance

The research has been carried out under production conditions on light gray forest soils with light particle-size composition at an area of 550 hectares where liquid pig manure (LPM) of a large pig breeding complex is annually used as an organic fertilizer at doses of 60 and 90 t/ha. The average characteristics of LPM are as follows: dry matter content is 9.5%, pH 7.7 units, nitrogen 0.22%, phosphorus 0.11%, and potassium 0.12%. The cultivated grain crops were presented by winter and spring wheat varieties, Moskovskaya 39 and Esther, respectively. It has been established that at the dose of 60 t/ha LPM for two years of research at an average a mean wheat yield was 3.0-3.75 t/ha, and at the dose of 90 t/ha - up to 4.75 t/ha. The return on investments for fertilizers in the “winter wheat → spring wheat” crop rotation link at the dose of 60 t/ha of LPM was 5.41 kg of grain per 1 kg of active substance of manure, at the dose of 90 t/ha - 4.57 kg / kg. A positive balance of nutritional elements developed on all fields, but it was better balanced when the dose of LPM was 60 t/ha and the yield was 3.0 t/ha of grain annually, or when the LPM dose was 90 t/ha and the yield of wheat was 4.75 t/ha. In this case, the estimated potassi-um supply of soil occurs at a lower rate than that of nitrogen and phosphorus. The application of 120 t of LPM during two years in total on loamy sand and of 180 t/ha on light loamy soil provided an increase in the content of mobile phosphorus compounds by 5-22 mg/kg, and potassium - by 11-30 mg/kg with a variation coefficient of 28-57% and 21-49%, respectively.

scholarly journals Flotation and Tailing Discarding of Copper Cobalt Sulfide Ores Based on the Process Mineralogy Characteristics

Minerals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1078
Author(s):  
Wentao Hu ◽  
Kai Tian ◽  
Zhengyang Zhang ◽  
Jiuchuan Guo ◽  
Xinwei Liu ◽  
...  
Keyword(s):  
Particle Size ◽  
Sulfide Mineral ◽  
Cobalt Sulfide ◽  
Sulfide Concentration ◽  
Total Recovery ◽  
Copper Sulfides ◽  
Fine Grained ◽  
Mineralogical Characteristics ◽  
Process Mineralogy ◽  
Mineralogical Characteristic

The mineral composition of copper–cobalt ores is more complex than that of copper sulfides, and it is also difficult to discard tailing efficiently in primary flotation for the fine-grained disseminated of ore. In this work, a mineral liberation analyzer (MLA) was employed to study the characteristics of minerals. As a significant mineralogical characteristic, the liberation degree of useful mineral aggregates was determined after grinding, and a correlation was established between the ore grinding size and mineralogical characteristics. The results showed that the adopted ore occurred in sulfide form. However, the particle size of the mineral’s monomer was fine grained, whereas its aggregate was coarse. The sulfide mineral aggregate obtained after primary grinding was selected as the recovery object, and its mineralogical characteristics, such as liberation degree and particle size, were investigated to promote total recovery in primary flotation. The copper–cobalt sulfide concentration was obtained at the following optimal conditions: the grinding size of −0.074 mm (65%), the aggregate’s liberation degree of 67%, a collector dosage of 50 g·t−1, a collector combination of 35% aerofloat + 65% butyl xanthate, a pH of 8.5, and 2# oil (a terpineol type foaming agent) dosage of 60 g·t−1. The recovered rough Cu and Co concentrates were 89.45% and 88.03%, respectively. Moreover, the grades of Cu and Co were 13.4% and 4.81%, respectively, with 85.07% of the ore weight discarded as tailing. The consideration of sulfide aggregates instead of singeral minerals mineralogy characters in primary grinding and primary flotation provides an effective theoretical guide for the sorting of sulfide minerals and reduction in the power consumption of grinding.

SHEAR STRENGTH AND STIFFNESS BEHAVIOR OF FINE-GRAINED SOILS AT DIFFERENT SURFACE HYDRATION CONDITIONS

2021 ◽  
Author(s):  
Jeongki Lee ◽  
Dante Fratta ◽  
Idil Deniz Akin
Keyword(s):  
Particle Size ◽  
Tensile Strength ◽  
Charge Density ◽  
Wave Velocity ◽  
Complex Function ◽  
Shear Stiffness ◽  
Experimental Program ◽  
S Wave ◽  
Interparticle Forces ◽  
Fine Grained

We developed an experimental program to monitor how interparticle forces control fine-grained soils' mechanical behavior when saturation changes from the tightly adsorbed regime to saturation. The testing program uses stiffness (i.e., S-wave velocity) and strength (i.e., Brazilian tensile strength) tests on kaolinite, silica flour, and diatomaceous earth soil samples at very low confining stresses (< 5 kPa). Three fine-grained soils yield a range of different properties, including particle size, specific surface area, negative charge density, and internal/external particle porosity. Results show that shear stiffness and tensile strength follow similar trends, emphasizing that the same interparticle forces control the mechanical responses. In particular, the interpretation of S-wave velocity measurements shows three different behavior ranges: a van der Waals attraction range, a capillary-dominated interparticle forces range, and the continuous decrease in the capillary forces from the saturation at the air-entry pressure until full saturation. We show that the interparticle forces respond to a complex function of water content, particle size, particle separations, surface charge density, and the presence of internal particle porosity.

Fine-Grained Concrete with Nanodispersed Silica Additive

2020 ◽  
Vol 992 ◽  
pp. 156-161
Author(s):  
N.P. Lukuttsova ◽  
E.G. Borovik ◽  
D.A. Pehenko
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Pore Diameter ◽  
Fine Grained ◽  
Silica Concentration ◽  
Calcium Hydrosilicates ◽  
Additive Particle ◽  
Nanodispersed Silica ◽  
Silica Additive ◽  
Number Of Particles

The effect of the modifying nanodispersed silica (NS) additive, obtained by the polycondensation method, on the properties of fine-grained concrete (FGC) is studied. It is revealed that the dependence of the NS-additive particle size on its age is extreme. The maximum number of particles of up to 100 nm in the additive is observed at the age of 10 days, and then their number decreases. However, it affects the FGC strength little even after 30 days of the additive storage. It is established that the NS-additive could be most effectively used with 0.23% of an active silica concentration and pH 4.1 in combination with S-3. At that, the porosity declines from 17.5 to 12.9% and the pore diameter diminishes from 3.171 to 0.689 μm. It leads to an increase in the compressive strength by 2 times and a decrease in water absorption by 1.6 times as compared to the control composition without additives. An increase in the frost resistance of the modified fine-grained concrete to F250 is recorded; it occurs due to a decrease in porosity at portlandite binding with amorphous silica additives into low-basic calcium hydrosilicates.

scholarly journals Effects of Tailings Gradation on Rheological Properties of Filling Slurry

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Bingwen Wang ◽  
Tingyong Xiong ◽  
Lijing Gao ◽  
Yuepeng Chai ◽  
Xiangyu Cui ◽  
...  
Keyword(s):  
Particle Size ◽  
System Design ◽  
Rheological Properties ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Analysis Software ◽  
Key Technology ◽  
Fine Grained ◽  
Viscosity Coefficients ◽  
Filling System

The key technology in filling mining is the gravity transportation of high-density slurries, and the filling system design is a significant part of this technology. The filling effect depends on the fluidity of the filling slurry. To investigate the influence of the gradation of tailings on the rheological properties of the filling slurry, this study uses particle size analysis to prepare three types of tailings: powder-, relatively fine-, and fine-grained tailings, which are then mixed in different proportions. The rheological properties of the resulting filling slurries are tested; the viscosity coefficients and yield stresses of the slurries are obtained using the analysis software provided with the MCR102 advanced rheometer that is used to measure the rheological properties of the slurries. The experimental results demonstrate that there is no absolute relationship between the rheological properties of the slurry and the size of the tailings particles, but the rheological properties are related to the gradation of tailings. Lubricating effect is weakened with an insufficient content of powder-grained particles in the tailings. On the contrary, when the content of powder-grained particles in the tailings is too high, the viscous substances in the slurry increase. Both of these conditions can increase the friction loss of the slurry.

Comparison of Urinary Crystallites from Patients with Renal Calculi with that from Healthy Subjects

2012 ◽  
Vol 554-556 ◽  
pp. 1738-1741 ◽  
Author(s):  
Zhi Yue Xia ◽  
Yi Ming Ding ◽  
Jian Ming Ouyang
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Calcium Oxalate ◽  
Healthy Subjects ◽  
Renal Calculi ◽  
Calcium Oxalate Monohydrate ◽  
Calcium Oxalate Dihydrate ◽  
Aggregation State ◽  
Particle Size Analyzer ◽  
Sharp Edges

The differences between the urinary crystallites from patients with renal calculi and healthy subjects were compared using SEM, XRD, and nano-particle size analyzer, etc. These differences concern morphology, aggregation state, number, particle size, crystal phase and Zeta potential, etc. About 90% of the crystallites had the particle sizes less than 20 μm, the Zeta potential was -(113) mV, and the composition included a large proportion of calcium oxalate dihydrate (COD) crystals. By comparison, the urinary crystallites from patients with renal calculi had sharp edges and corners and exhibited significant aggregation. There were more crystallites with the size greater than 20 μm in comparison with those in healthy subjects, their Zeta potential was -(73) mV, and calcium oxalate existed mainly in the form of calcium oxalate monohydrate (COM) crystals. The above differences increased the aggregation trend of the crystallites in lithogenic urine and caused the probability of renal calculi formation to increase.

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