• Journal of the Korean Geosynthetics Society
• /
• v.1 no.1
• /
• pp.43-51
• /
• 2002

In this study, free swell index of betonite was examined in several regeants; distilled water, leachate, seawater and 3% NaCl solution. Free swell index values of bontonite to be added Poly(acrlylic acid), PYA(Polyvinyl Alcohol) or SCMC (Sodium Carboxymethyl Cellulose) were evaluated and compared. From this, it was confirmed that hydraulic conductivities of GCL in seawater were examined and the hydraulic conductivities of GCL in seawater were compared to those in distilled water. The average values of free swell indices of bentonite were decreased in order of distilled water>leachate>seawater. It was shown that no significant differences were occurred for free swell index between seawater and 3% NaCl solution. For bentonite to be added PVA, the other reagents except distilled water didn't affect increase of swelling. Swelling properties of bentonite to be added SCMC were improved except 3% NaCl solution.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.24 no.1
• /
• pp.35-43
• /
• 2022

This study aims to analyze the physical properties of non-woven fabric sheets, which continue to grow in the cosmetic market. Non-woven fabric sheets were used as specimens, and a total of 17 samples were analyzed. To evaluate the physical properties of the non-woven fabric sheet, the weight, tensile strength, surface properties, free swell absorption, and wet stiffness were tested. Through the results itw was determined that non-woven fabric sheets for mask packs should be manufactured considering fiber arrangement so that the weight is 40 g/m², and the tensile strength should be maintained near 12 kgf. In addition, it was confirmed that the material selection and process conditions should be adjusted so that the free swell absorption is at least 8 g/g, and the wet stiffness is 200 mg. Therefore, since the non-woven fabrics for the mask sheets can be used in various products depending on fabric composition, this study will be expected to be basic data for the continuous growth of the sheet-type mask packs coming to market.

• Journal of the Korean earth science society
• /
• v.18 no.6
• /
• pp.559-564
• /
• 1997

The New Hebrides Basin is an inactive non back-arc basin located at the convergent boundary of the Pacific and Info-Australian plates. This basin was formed from 46 Ma to 60 Ma. The basin has two spreading episodes with rates of 34 mm/a for 42 to 47 Ma and 17 mm/a for 47 to 60 Ma. The sediments covered in the basin has uniform thickness of 0.65 sec. The age-depth correlation curve of the New Hebrides Basin can be represented by the following equation: $Depth(m)=2689+312\sqrt{Age}(Ma)$ The coefficient of 312 in this equation is close to that for major oceans, 350. This suggests that the cooling processes of the lithospheres in the New Hebrides Basin and major oceans are similar to each other. Free-air gravity anomalies of the basin varying from -22.3 mgal to +59.0 mgal. The mean value is +30.2 mgal higher than those of the normal oceans. Moderately large free-air gravity anomalies in the New Hebrides Basin are presumably owing to its location on a marginal swell along the New Hebrides Trench. It is generally observed that the ocean floor is very gently uplifted in a zone about 200 km oceanward of the trench axis. Positive free-air gravity anomalies amounting to $50{\sim}60$ mgal are usually observed on the crest of the swell. This topography is presumably by bending of the oceanic lithosphere so as to dynamically maintain nonisostatic states for some duration.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.09a
• /
• pp.395-398
• /
• 2003

Geosynthetic Clay Liners(GCLs) have been widely used as hydraulic barrier in landfills and remediation projects of contaminated sites. The aim of this research is to modify GCLs for effective removal of contaminants. We perform the free swell test, hydraulic conductivity test, and contaminants (TCE, hexavalent chromium, and nitrate) removal test on the bentonite-ZVI mixture with various ZVI content. As the ZVI content increased, contaminants removal efficiencies and swell volume increased, and hydraulic conductivity decreased.

• Geomechanics and Engineering
• /
• v.22 no.3
• /
• pp.227-236
• /
• 2020

Expansive soils are renowned for their swelling-shrinkage property and these volumetric changes resultantly cause huge damage to civil infrastructures. Likewise, subgrades consisting of expansive soils instigate serviceability failures in pavements across various regions of Pakistan and worldwide. This study presents the use of polypropylene fibers to improve the engineering properties of a local swelling soil. The moisture-density relationship, unconfined compressive strength (UCS) and elastic modulus (E₅₀), California bearing ratio (CBR) and one-dimensional consolidation behavior of the soil treated with 0, 0.2, 0.4, 0.6 and 0.8% fibers have been investigated in this study. It is found that the maximum dry density of reinforced soil slightly decreased by 2.8% due to replacement of heavier soil particles by light-weight fibers and the optimum moisture content remained almost unaffected due to non-absorbent nature of the fibers. A significant improvement has been observed in UCS (an increase of 279%), E₅₀ (an increase of 113.6%) and CBR value (an increase of 94.4% under unsoaked and an increase of 55.6% under soaked conditions) of the soil reinforced with 0.4% fibers, thereby providing a better quality subgrade for the construction of pavements on such soils. Free swell and swell pressure of the soil also significantly reduced (94.4% and 87.9%, respectively) with the addition of 0.8% fibers and eventually converting the medium swelling soil to a low swelling class. Similarly, the compression and rebound indices also reduced by 69.9% and 88%, respectively with fiber inclusion of 0.8%. From the experimental evaluations, it emerges that polypropylene fiber has great potential as a low cost and sustainable stabilizing material for widespread swelling soils.

• Geotechnical Engineering
• /
• v.5 no.2
• /
• pp.57-77
• /
• 1989

This paper describes the design and construction aspects of time-dependent deformation test apparatus for slut.oiling rocks and presents the test results obtained using these apparatus. These tests are modified semi-confined swell test, swell test under uniaxial tension and swell test under biaxial stress. These apparatus measure the time.dependent deformations in three orthogonal directions of the test specimen under simplified field stress conditions. The test results obtained from these test apparatus for the last several years show that these apparatus have performed satisfactorily. The test results show that the time-dependent deformation behaviour of the Queenston shale is cross-anisotropic with higher swelling in the vertical direction (normal to bedding plane) than in horizontal direction (parallel to bedding plane) under free swell condition. The applied stress in one direction suppresses the swelling deformation in that direction as well as that in the orthogonal directions.

• Geomechanics and Engineering
• /
• v.19 no.1
• /
• pp.21-28
• /
• 2019

Use of cement in stabilizing the sulfate-bearing clay soils forms ettringite/ thaumasite in the presence of moisture leads to excessive swelling and causes damages to structures built on them. The development and use of non-traditional stabilisers such as alkali activated ground granulated blast-furnace slag (AGGBS) and enzyme for soil stabilisation is recommended because of its lower cost and the non detrimental effects on the environment. The objective of the study is to investigate the effectiveness of AGGBS and enzyme on improving the volume change properties of sulfate bearing soil as compared to ordinary Portland cement (OPC). The soil for present study has been collected from Tilda, Chhattisgarh, India and 5000 ppm of sodium sulfate has been added. Various dosages of the selected stabilizers have been used and the effect on plasticity index, differential swell index and swelling pressure has been evaluated. XRD, SEM and EDX were also done on the untreated and treated soil for identifying the mineralogical and microstructural changes. The tests results show that the AGGBS and enzyme treated soil reduces swelling and plasticity characteristics whereas OPC treated soil shows an increase in swelling behaviour. It is observed that the swell pressure of the OPC-treated sulfate bearing soil became 1.5 times higher than that of the OPC treated non-sulfate soil.

• Geomechanics and Engineering
• /
• v.38 no.4
• /
• pp.353-366
• /
• 2024

Organic soils pose significant challenges in geotechnical engineering due to their high compressibility and low stability, which can result in issues like differential settlement, rutting, and pavement deformation. This study explores effective methods for stabilizing organic soils. Rather than conventional ordinary Portland cement (OPC), the focus is on using environmentally friendly calcium sulfoaluminate (CSA) cement, known for its rapid setting, high early strength development, and environmental benefits. Mechanical behavior is analyzed through 1-D free swell, unconfined compressive strength (UCS), and bender element (BE) tests. Microstructural analyses, including Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), characterize the soil mixed with CSA cement. Experimental results demonstrate improved soil properties with increasing cement dosage and curing periods. A notable strength increase is observed in soil samples with 15% cement content, with UCS doubling after 7 days. This trend aligns with shear wave velocity results from the BE test. SEM and FTIR spectroscopy reveal how CSA cement hydration forms hydrated calcium silicate gel and ettringite, enhancing soil properties. CSA cement is recommended for reinforcing organic subgrade soil due to its eco-friendly nature and rapid strength gain, contributing to improved durability.

• The Journal of Natural Sciences
• /
• v.8 no.1
• /
• pp.145-151
• /
• 1995

The stretching of synthetic fibers by hot dry process is very difficult, because these fibers have high glass transition temperature at above $150^{\circ}C$. But, we used a swell-wet stretching precess; the fibers are stretched in a swelling agent such as organic solvents at lower temperature. In this study, 100% acryl fibers were uniaxially stretched with free width at $70^{\circ}C$ by swell-wet process in organic solvents. The stretchability was estimated by stretching work. This work is concerned with stretching stress and strain, and initial modulus. We found that it is a good parameter for the estimatation of high strength to the acrylic fiber. The effects of stretching conditions on the molecular orientation for high strength and mechanical properties of PAN fibers were measured.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1989.10a
• /
• pp.1.3-25
• /
• 1989

This paper describes procedures and the results of mineralogical, fabric and pore sixte analyses perforied on four shales to understand time-dependent deforiation behav iour of swell ins shales better. Mineralogical compositions of theme shales are eBtablished froi the results of X-ray diffraction snalysis and chemical analyses. The importance of the fabric in the understanding of swelling behaviour of shales is demonstrated using Scanning Electron Microscope (SRI). The change in pore sixte distribution during the process of swelling is investigated by measuring pore size distribution before and after free swell test. The results Of the Present study imply that the swelling of Shales studied is not attributed to minerals like pyritei anhydrite or swelling clay minerals. The anisotropic swelling behaviour of shales studied ray be explained by fabrics of theme shales and the difference in them. The swelling of theme shales is found to be accoipanied by increase in the volute of pores.