Effect of slag and bentonite on shear strength parameters of sandy soil

Sabbar, Ayad Salih,Chegenizadeh, Amin,Nikraz, Hamid Techno-Press 2018 Geomechanics & engineering Vol.15 No.1

A series of direct shear tests were implemented on three different types of specimens (i.e., clean Perth sand, sand containing 10, 20 and 30% bentonite, sand containing 1, 3 and 5% slag, and sand containing 10, 20 and 30% bentonite with increasing percentages of added slag (1%, 3% and 5%). This paper focuses on the shear stress characteristics of clean sand and sand mixtures. The samples were tested under different three normal stresses (100, 150 and 200 kPa) and three curing periods of no curing time, 7 and 14 days. It was observed that the shear stresses of clean sand and mixtures were increased with increasing normal stresses. In addition, the use of slag has improved the shear strength of the sand-slag mixtures; the shear stresses rose from 128.642 kPa in the clean sand at normal stress of 200 kPa to 146.89 kPa, 154 kPa and 161.14 kPa when sand was mixed with 1%, 3% and 5% slag respectively and tested at the same normal stress. Internal friction angle increased from $32.74^{\circ}$ in the clean sand to $34.87^{\circ}$, $37.12^{\circ}$ and $39.4^{\circ}$ when sand was mixed with 1%, 3% and 5% slag respectively and tested at 100, 150, and 200 kPa normal stresses. The cohesion of sand-bentonite mixtures increased from 3.34 kPa in 10% bentonite to 22.9 kPa, 70.6 kPa when sand was mixed with 20% and 30% bentonite respectively. All the mixtures of clean sand, different bentonite and slag contents showed different behaviour; some mixtures exhibited shear stress more than clean sand whereas others showed less than clean sand. The internal friction angle increased, and cohesion decreased with increasing curing time.

제주 해안지역 모래의 압축 특성

남정만,조성환,김태형 한국지반공학회 2007 한국지반공학회논문집 Vol.23 No.6

Sands distributed in Jeju island’s coastal areas, Korea, can be classified as silicate sand derived from volcanic rock, carbonate sand derived from shells, and mixed sands containing both silicate and carbonate sands. These three types of sands typically exist in Jeju coastal areas. Samples of silicate, carbonate and mixed sands were obtained from Samyang beach, Gimnyeong beach, and Jeju harbor area, respectively. Compression tests were conducted to assess the compression characteristics of these sands. As a result of these tests, each sand showed different behaviors. For Samyang beach sand, it appeared that initial compression is a larger than the other two sands. For Gimnyeong and Jeju harbor sands, however, the additional compression occurred after initial compression. This could result from the crushing, shattering, and rearrangement of sand particles. In addition, settlement behavior of Jeju harbor ground according to the construction stages was analyzed using the measured data. It showed that in addition to the initial elastic compression, a considerable additional compression occurred with time. The settlements of Jeju harbor ground were predicted by using the elastic settlement calculation methods (empirical methods) and the compression test method. The empirical methods, which did not consider the crushing, shattering, and rearrangement of particles could show smaller result than that occurring actually.

Effect of hanging-type sand fence on characteristics of wind-sand flow fields

Cheng, Jian-jun,Lei, Jia-qiang,Li, Sheng-yu,Wang, Hai-feng Techno-Press 2016 Wind and Structures, An International Journal (WAS Vol.22 No.5

A hanging-type sand-retaining wall is a very common sand-blocking fence structure used to prevent sand movement. This type of wall is widely used along the Qinghai-Tibet and Gobi desert railways in Xinjiang, Western China. To analyze the characteristics of wind-sand flow fields under the effect of such a sand fence structure, a wind tunnel test and a field test were carried out. The wind tunnel test showed the zoning characteristics of the flow fields under the effect of the hanging-type sand-retaining wall, and the field test provided the sediment transport data for effective wind-proof interval and the sand resistance data in the front and behind the sand-retaining wall. The consistency of the wind-sand flow fields with the spatial distribution characteristic of wind-carried sand motion was verified by the correspondences of the acceleration zone in the flow field and the negative elevation points of the percentage variations of the sand collection rate. The spatial distribution characteristic of the field sand collection data further showed the spatial structural characteristic of the sandy air currents under the action of the hanging-type sand-retaining wall and the sand resistance characteristic of the sand-retaining wall. This systematic study on the wind-sand flow fields under the control of the hanging-type sand-retaining wall provides a theoretical basis for the rational layout of sand control engineering systems and the efficient utilization of a hanging-type sand-retaining wall.

순환잔골재를 사용한 모르터의 물성에 관한 연구

현철 경성대학교 공학기술연구소 2010 공학기술연구지 Vol.16 No.-

Lately, Korea government recommends that concrete maker use more recycled sand in concrete production. Recycled sand needs consuming way because waste concrete cause environmental problems in case of burying in the ground. But the influence of recycled sand about concrete properties including strength and workability is not perfectly researched. Therefore, it is very necessary for recycled sand to be studied about cocrete properties. The aim of this study is to investigate the influence of recycled sand on the properties of mortars that included three different recycled sands. The properties of the mortars were tested with four kinds of sands including three recycled sands and natural sand. The mortars were prepared with the same content. A reference mix was prepared with 100% natural sand, and it was gradually replaced by each recycled sand. The compressive strength of mortars with mixed sands decreased as recycled sand replaced natural sand. In this paper the parameters of Bingham model about cement mortar with recycled were also investigated. According to mix ratio with three recycled sands, the rheological properties of cement mortar were changed. However, slump test or flow test do not allow to obtain information concerning more fundamental phenomena. Rheology has also been used to study the mechanical properties of cement mortar from mixing up to setting. Superplasticiser (SP) was not used. A general mixer was used to study rheology during the very first minutes following the end of mixing. This study evaluated the effect of water/cement ratio (W/C), types of recycled sands and replacement ratio of recycled sand in mortar. The rheometer was used for testing the behaviour of cement mortar.

大形鑄鋼의 燒着과 그 對策 : Chromite Sand를 中心으로

郭士濩,姜朝遠 조선대학교 생산기술연구소 1980 生産技術硏究 Vol.1980 No.-

chromite砂中의 不純物이 燒着現象에 미치는 영향을 調査하고 그 發生機構와 對策을 究明하기 위해 不純物 含量이 각각 틀린 3種의 實驗用 core를 製作하여 鑄入함으로써 core에의 溶鋼 浸透狀況을 調査하였다. 또 Table 5에 있는 化學成分으로 試片을 만들어 1000℃∼1400℃ 溫度 범위에서 그의 熱間壓縮强度를 測定했다. 實驗結果를 要約하면 다음과 같다. (1) chromite sand에는 SiO₂, MgO and FeO 系와 SiO₂,MgO, Al_(2)O_(3) 系의 2種類의 不純物이 있었다. (2) chromite sand中의 不純物含量이 많으면 많을수록 浸透는 깊어지고 chromite sands의 燒結은 심해졌다. (3) chromite sand中에 不純物이 많으면 chromite sand의 耐燒着性이 감소하고 燒着現象의 發生이 容易하였다. (4) 1100℃∼1300℃에서 chromite sand의 燒結은 砂粒間物質 때문이 아니고 chromite 粒子들끼리의 直接結合에 의해 發生한 것이다. In order to clarify the mechanism of metal penetration and prevent the defect for heavy section steel castings, 3 kinds of cores with each different amount of impurities were prepared and investigated. And that in the range of 1000℃ to 1400℃ the hot compressive strength of specimen of the chemical component in Table5 was measured. The results obtained are summarized as follows: 1) Two kinds of impurities were contained in chromite sands; one was largely composed of SiO₂, MgO and FeO, and the other largely of SiO₂,MgO and Al_(2)O_(3). 2) The more the content of impurities of chromite sands was, the deeper and severer the metal penetration was. 3) In case much impurities are contained in chromite sands, the resistance of chromite sand mold to metal penetration was reduced and metal penetration was liable to occur. 4) Impurity grains over 1200℃ lowered the hot compressive strength of chromite sands. 5) The sintering of chromite sand mold in the range of 1100℃∼1300℃ occurs, not because of the substance among the sand grains, but because of the direct bonding of chromite grains.

물유리계 바인더로 제조한 천연주물사와 인공주물사 중자의 강도 특성

배민아,김판성,김경호,이만식,백재호 대한금속·재료학회 2021 대한금속·재료학회지 Vol.59 No.4

Natural sand and organic binders are commonly used in casting processes, but these ingredients produce environmental problems with dust and harmful TVOC(Total Volatile Organic Carbon) gases. Research on the introduction of artificial sand and inorganic binders to solve these environmental problems is being actively conducted mainly in the casting industry. Artificial sand has superior durability and a spherical shape compared to natural sand, and above all, it does not generate dust. In addition, inorganic binders have the advantage that no harmful gas is generated during casting and the used sand can be recycled. This study confirmed whether inorganic binders can be applied when replacing natural sand with artificial sand. First, eco-friendly inorganic binders that do not produce harmful gas were synthesized. Then characteristic analyses were carried out with artificial sand and natural sand. Physical and chemical properties were compared using X-Ray Fluorescence (XRF), Powder Flow Test (PFT) and particle size distribution analyses. The general strength and absorption (absolute humidity 29.9 g/cm3) strength of the sample core was measured using each sand (artificial sand, natural sand) and inorganic binder. Also, X-ray Photoelectron Spectroscope (XPS) analysis confirmed the combination structure. As a result, it was confirmed that artificial sand exhibited mold characteristics with similar strength even with lower inorganic binder content than natural sand.

Standard sand for geotechnical engineering and geoenvironmental research in Nigeria: Igbokoda sand

Ojuri, Oluwapelumi O.,Fijabia, David O. Techno-Press 2012 Advances in environmental research Vol.1 No.4

This study entails establishing reference standard sand in Nigeria for engineering and geoenvironmental research work. Sands from four geographical locations in southwestern Nigeria were examined for baseline geotechnical and mineralogical properties. A total of sixteen sand samples were collected. The samples were air dried and subjected to tests in accordance with standard specifications. The tests carried out were: specific gravity, grain size analysis, moisture content, bulk density, porosity, void ratio, chemical analysis, X-ray diffraction and Differential Thermal Analysis. The properties of the samples were compared with a standard (Ottawa sand in Illinois of the United States) in order to find out which of the four samples selected from southwestern Nigeria could serve as standard baseline sand. The results show that Igbokoda sand has geotechnical and mineralogical characteristics closest to Ottawa sand. It was therefore concluded that Igbokoda sand could be used as a standard baseline sand for research work in southwestern Nigeria and other parts of Nigeria since it needs little processing to bring it to the same level as standard baseline sand, like the Ottawa sand.

The use of river sand for fine aggregate in UHPC and the effect of its particle size

Kang, Su-Tae Techno-Press 2020 Advances in concrete construction Vol.10 No.5

For the purpose of improving the properties of UHPC as well as the economic efficiency in production of the material, Availability of river sands as fine aggregate instead of micro silica sand were investigated. Four different sizes of river sands were considered. Using river sand instead of micro silica sand increased the flowability, and decreased the yield stress and plastic viscosity in rheological properties, and the effect was higher with larger particle size of river sand. It was demonstrated by analyses based on the packing density. In the results of compressive strength and elastic modulus, even though river sand was not as good as micro silica sand, it could provide high strength of over 170 MPa and elastic modulus greater than 40 GPa. The difference in compressive strength depending on the size of river sand was explained with the concept of maximum paste thickness based on the packing density of aggregate. The flexural performance with river sand also presented relatively lower resistance than micro silica sand, and the reduction was greater with larger particle size of river sand. The flexural performance was proven to be also influenced by the difference in the fiber orientation distribution due to the size of river sand.

Wet regeneration of waste artificial sand used in sand casting using chemical solutions

Eun Yeong Ko,Kyeong Ho Kim,Jae Ho Baek,Inseong Hwang,Man Sig Lee 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.6

Natural sand and organic binders have been the main materials used in sand casting. However, inorganic binders are used in novel casting technologies, and research on artificial sand as a substitute of natural sand has been conducted. Herein, the wet regeneration of waste artificial sand was performed using a sodium silicate binder. Acidic, neutral, and basic solutions were used for wet regeneration. The effects of binder removal and reusability of the regenerated sand were investigated by comparing the characteristics and strengths of the artificial and regenerated sand. It was demonstrated that the basic solution effectively removed the binder from the surface of the waste artificial sand. The Si-O-Si bond cleavage in the binder occurred due to the high concentration of hydroxide ions in the basic solution. The strength of the regenerated sand treated with the basic solution and that of the artificial sand were similar. Moreover, the strengths of regenerated sands treated with the acidic or neutral solutions were lower than that of artificial sand due to the presence of residual binder. These results indicated that the basic solution was suitable for removing the sodium silicate binder. The quality of the regenerated sand was similar to that of artificial sand.

2002년 부산지역 봄철 황사/비황사시 PM10 중의 중금속 농도 특성

전병일 ( Byung Il Jeon ) 한국환경영향평가학회 2003 환경영향평가 Vol.12 No.2

We collected and analyzed PM10 samples to account for the characteristics of heavy metallic elements for yellow sand and non-yellow sand during springtime of 2002 at Busan, The mean PM10 mass concentrartion for springtime of 2002 was 219.82㎍/㎥ with the maximum 787.50㎍/㎥ and the minimum 19.44㎍/㎥. The mean concentration of metallic elements contained in PM10 are shown as follows:Si>Ca>Fe>Al>Na,respectively. The ratio of mean PM10 mass concentratio for yellow sand(362.7㎍/㎥) was 7.5, the significant positive correlation (p<0.05)was found between yellow sand and non-yellow sand. The metallic elemects concentration ratios of yellow sand to non-yellow sand were over 10 times for Al,Ca,Mg,4∼8times for Fe,Si,Mn, But the concentration of Na,Cu,Zn for non-yellow sand was higher than those yellow sand was higher that of non-yellow sand over 10times, and concentration rate of soil particles of yellow sand was increased 2.3times that of non-yellow sand.