Hydraulic conductivity variation in compacted bentonite-fly ash mixes under constant volume and free swelling flow conditions

2021 ◽  
Author(s):  
Chandra Bhanu Gupt ◽  
Sanandam Bordoloi ◽  
Metta Niranjan Bhatlu ◽  
Sreedeep Sekharan
Keyword(s):  
Fly Ash ◽  
Hydraulic Conductivity ◽  
Constant Volume ◽  
Upper And Lower Bounds ◽  
Power Relationship ◽  
Compacted Bentonite ◽  
Free Swelling ◽  
Extended Duration ◽  
Class C ◽  
The Difference

Compacted bentonite-sand (B-S) and bentonite-fly ash (B-FA) are established combinations for the construction of landfill liners. This study determined the upper and lower bounds of equilibrium hydraulic conductivity (keq) of amended bentonite under extended duration of flow. The keq for constant volume flow condition differed from free swelling condition by more than two orders of magnitude due to the difference in geomaterial interaction, microstructural changes, and mineralization. Considering constant volume and free swelling condition, B-FA mix with class F and class C fulfilled the hydraulic conductivity criterion up to 70 % and 30 % amendment, respectively. The higher keq observed for the B mixed with class C FA was attributed to the formation of porous calcium aluminium silicate hydrate gel and ettringite needle type minerals. The time taken to achieve equilibrium was inversely related to keq by a power relationship. The data from this study were used to propose empirical relationships for estimating keq (long-term) based on k obtained at 48 hours (short-term), plasticity and geomaterial type. The study reveals that FA can be used as an alternate for S as amendment material and keq based on free swelling condition should be used for designing the liner.

Laboratory Experiments on the Alteration of Highly-Compacted Bentonite by Alkaline Solution and the Effects on Physical Properties

2011 ◽  
Author(s):  
Satoru Miyoshi ◽  
Shinya Morikami ◽  
Yukinobu Kimura ◽  
Tomoko Jinno ◽  
Shuichi Yamamoto
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Solution ◽  
Sodium Hydroxide Solution ◽  
Mineral Dissolution ◽  
Alkali Solution ◽  
Exchangeable Cation ◽  
High Concentration ◽  
Compacted Bentonite ◽  
Aqueous Silicon ◽  
The Difference

The laboratory experiment was done that 1.0mol/L sodium hydroxide solution was injected to the compacted bentonite whose density is the same as the prospected value in the concept of the intermediate-level disposal in Japan in the circumstance of 70°C temperature. After the injection of the alkali solution for approximately 600 days, the bentonite was taken out of the apparatus and some sorts of analysis were done. The accompanying minerals in the bentonite, calcedony and quartz, were dissolved and disappeared in XRD charts. Then analcime was precipitated as a secondary mineral. Although montmorillonite was dissolved, the mass fraction of it was kept approximately. The hydraulic conductivity of the bentonite calculated using the flow rate at the end of the injection of alkali solution was smaller than the prospected value based on a widely-used empirical model of the hydraulic conductivity of compacted bentonite as a function of the equivalent concentration of pore solution, montmorillonite partial void ratio, and the ratio of sodium ion equivalent to the exchangeable cation equivalent. The reasons for the difference were supposed to be the decrease of pore size brought by mineral dissolution and the large viscosity of pore solution involving high concentration aqueous silicon.

Characterization of Coal Fly Ash, Bottom Ash and their Possibilities as Catalysts for Biodiesel Production

2021 ◽  
Vol 904 ◽  
pp. 413-418
Author(s):  
Wilasinee Kingkam ◽  
Sasikarn Nuchdang ◽  
Dussadee Rattanaphra
Keyword(s):  
Fly Ash ◽  
Palm Oil ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Bottom Ash ◽  
Biodiesel Production ◽  
Catalyst Loading ◽  
Free Lime ◽  
Operation Conditions ◽  
Class C

Coal fly ash (CFA) and bottom ash (BA) obtained from coal fired power plants in Thailand and local supplier were characterized using XRF, XRD and N2 adsorption-desorption techniques. Their possibilities for conversion of palm oil into biodiesel were investigated. Selected CFA was also modified with lanthanum (La) at different La loading and the influence of La loading on biodiesel conversion was evaluated. The resulted showed that the Class C CFA as contained large amount of CaO (free lime) could catalyze the transesterification to achieve the highest FAME content of 89% under the operation conditions; the reaction temperature of 200 °C, the reaction pressure of 39 bars, the catalyst loading of 5 wt% of oil, the molar of oil to methanol of 1:30 and the stirring speed of 600 rpm for 5 h. The addition of La on the Class C CFA had a negative effect on conversion of palm oil. The FAME content decreased gradually from 89 to 62% with increasing La loading from 0 to 1 wt%.

Influence of Temperature on Hydraulic Conductivity in Compacted Bentonite

1997 ◽  
Vol 506 ◽  
Author(s):  
W. J. Cho ◽  
J. O. Lee ◽  
K. S. Chun
Keyword(s):  
Hydraulic Conductivity ◽  
Influence Of Temperature ◽  
Temperature Range ◽  
Compacted Bentonite ◽  
Influence Of Temperature On ◽  
Water Saturated ◽  
Increasing Temperature ◽  
Good Agreement

ABSTRACTThe hydraulic conductivities in water saturated bentonites at different densities were measured within temperature range of 20 to 80 °C. The results show that the hydraulic conductivities increase with increasing temperature. The hydraulic conductivities of bentonites at the temperature of 80 °C increase up to about 3 times as high as those at 20 °C. The measured values are in good agreement with those predicted. The change in viscosity of water with temperature contributes greatly to increase of hydraulic conductivity.

scholarly journals Effects of Hydraulic Gradient and Clay Type on Permeability of Clay Mineral Materials

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1064
Author(s):  
Masanori Kohno
Keyword(s):  
Hydraulic Conductivity ◽  
Specific Surface ◽  
Surface Area ◽  
Clay Mineral ◽  
Specific Surface Area ◽  
Hydraulic Gradient ◽  
Consistency Index ◽  
Hydrogen Energy ◽  
The Difference ◽  
Mineral Type

Considering the relevance of clay mineral-bearing geomaterials in landslide/mass movement hazard assessment, various engineering projects for resource development, and stability evaluation of underground space utilization, it is important to understand the permeability of these clay mineral-based geomaterials. However, only a few quantitative data have been reported to date regarding the effects of the clay mineral type and hydraulic gradient on the permeability of clay mineral materials. This study was conducted to investigate the permeability of clay mineral materials based on the clay mineral type, under different hydraulic gradient conditions, through a constant-pressure permeability test. Comparative tests have revealed that the difference in the types of clay mineral influences the swelling pressure and hydraulic conductivity. In addition, it has been found that the difference in water pressure (hydraulic gradient) affects the hydraulic conductivity of clay mineral materials. The hydraulic conductivity has been found to be closely associated with the specific surface area of the clay mineral material. Furthermore, the hydraulic conductivity value measured is almost consistent with the value calculated theoretically using the Kozeny–Carman equation. Moreover, the hydraulic conductivity is also found to be closely associated with the hydrogen energy, calculated from the consistency index of clay. This result suggests that the hydraulic conductivity of clay mineral materials can be estimated based on the specific surface area and void ratio, or consistency index of clay.

scholarly journals PEMANFAATAN LIMBAH FLY ASH DARI PEMBAKARAN BATUBARA PADA PEMBUATAN SEMEN PCC (PORTLAND COMPOSITE CEMENT) DI PT SEMEN XYZ LAMPUNG

2020 ◽  
Vol 4 (2) ◽  
Author(s):  
Dwi Septiyana Sari ◽  
◽  
Susanti Sundari
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Raw Materials ◽  
Testing Machine ◽  
Technical Aspect ◽  
Raw Material ◽  
Physical Test ◽  
Composite Cement ◽  
The Difference ◽  
The Cost

Abstract This study discusses the use of fly ash waste from coal burning on the manufacture of PCC (Portland composite cement) at PT. XYZ Lampung. The purpose of this research is to look at the technical studies and the efficiency of raw materials in the use of fly ash in cement making, in this case PCC cement (Portland Composite Cement). The steps taken in analyzing the data in this study were viewed from a technical aspect by means of a physical test, namely the cement compressive strength test at the age of 3 days, 7 days, and 28 days using the Compression Testing Machine. This test was conducted to see the comparison of the compressive strength of PCC cement using limestone and fly ash as raw materials, then calculate the difference in raw material costs in the year before and after the replacement of limestone with fly ash. The results showed that cement with the addition of fly ash after 3 days, 7 days and 28 days had an increased compressive strength value, which increased 21.69%, 16.07% and 8.05% respectively of the compressive strength of cement using limestone. The use of fly ash as a substitute for limestone has an effect on the cost of raw materials, where the difference between the cost of raw materials in 2019 and the cost of raw materials in 2018 is Rp. 39,440,952,074.

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