scholarly journals Treatment of a collapsible soil using a bentonite–cement mixture

2018 ◽  
Vol 40 (4) ◽  
pp. 233-243 ◽  
Author(s):  
Soumia Bellil ◽  
Khelifa Abbeche ◽  
Ouassila Bahloul
Keyword(s):  
Arid Regions ◽  
Soil Aggregates ◽  
Spectroscopy Analysis ◽  
Collapsible Soil ◽  
Collapse Potential ◽  
Collapsible Soils ◽  
Before And After ◽  
Cement Mixture ◽  
Different Levels ◽  
Stable Material

Abstract The study of collapsible soils that are generally encountered in arid and semi-arid regions remains a major issue for geotechnical engineers. This experimental study, carried out on soils reconstituted in the laboratory, aims firstly to present a method of reducing the collapse potential to an acceptable level by treating them with different levels of bentonite–cement mixture while maintaining the water content and degree of compactness, thus reducing eventual risks for the structures implanted on these soils. Furthermore, a microscopic study using scanning electron microscopy was carried out to explore the microstructure of the soil in order to have an idea of the phenomena before and after treatment. The results show that treatment with a bentonite–cement mixture improves the geotechnical and mechanical characteristics, modifies the chemical composition of the soil, reduces the collapse potential and the consistency limits. The microstructural study and the X-ray energy dispersive spectroscopy analysis clearly illustrate an association of elementary particles in the soil aggregates, whereby the arrangement of these aggregates leads to the formation of a dense and stable material.

scholarly journals Soil Improvement Using Waste Marble Dust for Sustainable Development

2021 ◽  
Vol 7 (9) ◽  
pp. 1594-1607
Author(s):  
Abdul Waheed ◽  
Muhammad Usman Arshid ◽  
Raja Abubakar Khalid ◽  
Syed Shujaa Safdar Gardezi
Keyword(s):  
Soil Improvement ◽  
Considerable Improvement ◽  
Collapsible Soil ◽  
Geotechnical Parameters ◽  
Suitable Material ◽  
Collapse Potential ◽  
Collapsible Soils ◽  
Marble Dust ◽  
Loss Of Strength ◽  
Very High

The soils which show very high shear strength in a dry state but rapidly lose their strength on wetting are known as collapsible soils. Such rapid and massive loss of strength produces severe distress leading to extensive cracking and differential settlements, instability of building foundations, and even collapse of structures built on these soils. Waste marble dust is an industrial byproduct and is being produced in large quantities globally poses an environmental hazard. Therefore, it is of the utmost need to look for some sustainable solution for its disposal. The present study focused on the mitigation of the collapse potential of CL-ML soil through a physio-chemical process. The soil is sensitive to wetting, warranting its stabilization. Waste marble dust (WMD) in varying percentages was used as an admixture. The study's optimization process showed that geotechnical parameters of collapsible soil improved substantially by adding waste marble dust. Plasticity was reduced while Unconfined Compressive Strength (UCS) significantly increased while swelling was reduced to an acceptable limit. The California Bearing Ratio (CBR) also exhibits considerable improvement. This study appraises the safe disposal of hazardous waste safely and turns these into suitable material for engineering purposes. Doi: 10.28991/cej-2021-03091746 Full Text: PDF

scholarly journals Microstructural analysis of collapsible soil before and after collapse and with loading and unloading cycle

2021 ◽  
Vol 337 ◽  
pp. 01004
Author(s):  
Ilton Alves ◽  
Larissa Costa ◽  
Antônio Antonino ◽  
Lícia Costa ◽  
Silvio Ferreira
Keyword(s):  
Microstructural Analysis ◽  
Microstructure Analysis ◽  
Collapsible Soil ◽  
Clay Particles ◽  
Soil Microstructure ◽  
The Third ◽  
Collapsible Soils ◽  
Three Samples ◽  
Before And After ◽  
X Ray Computed

Aspects related to the volume variation of collapsible soils due to the change in water content are influenced by several factors, including the microstructure. The microstructure analysis of the soil is especially important in order to understand these aspects. This paper shows a comparative analysis of the microstructure of three samples of a collapsible Yellowish Red Sand from the district of Petrolina (northeast of Brazil), carried out by means of two techniques: Scanning Electron Microscope (SEM) and X-Ray Computed Tomography. Three undisturbed sample were used: the first no pressure was applied, in the second an one-dimensional compression of 160 kPa was applied and then the sample was unloaded, and in the third, between the compression and decompression, the sample was flooded with the occurrence of structural collapse. In the first sample, the soil microstructure is a matrix with a predominance of grains of sand clothed with iluvial clay with interconnected pores that confers instability. The second sample showed a reduction in macropores after loading. In the third sample the structure remained with a simple packing arrangement, however, there is a greater packing between the grains, in addition to the wetting-induced softening of the clay particles that fill in the voids. It is also observed, through the radiodensity analysis that at the top and bottom of the second and third samples there was an increase in volume due to the stress relief that is not observed in the central section of the samples. The two microstructure analysis techniques are complementary.

scholarly journals Experimental evaluation of the classical and alternative consolidation theories in predicting the volumetric change of contaminated and non-contaminated soil

2021 ◽  
Vol 44 (4) ◽  
pp. 1-10
Author(s):  
Moisés Lemos ◽  
Lucas Guimarães ◽  
André Cavalcante
Keyword(s):  
Hydraulic Conductivity ◽  
Alternative Interpretation ◽  
Saturated Hydraulic Conductivity ◽  
Southeastern Brazil ◽  
Collapsible Soil ◽  
Collapse Potential ◽  
Collapsible Soils ◽  
Total Settlement ◽  
Consolidation Coefficient ◽  
Guelph Permeameter

Several regions in Brazil and the world suffer from the presence of collapsible soils. The development of theories for understanding the phenomenon is significant because the increase of water content is associated with several reasons (e.g., precipitation, rupture of sewage, and water systems). Although some theories explain the behavior of various types of soils, they fail to explain collapsible and structured soils. In this research, an alternative interpretation of the consolidation theory is verified and calibrated for collapsible soil. The alternative model was applied to experimental data from a latosol from southeastern Brazil, and comparisons with the classical theory showed a difference in the saturated hydraulic conductivity of around 100 times. The observation showed promising results compared with the saturated hydraulic conductivity of the field (Guelph Permeameter). Furthermore, consolidation tests verified the collapse potential, the variation of consolidation coefficient and saturated hydraulic conductivity, and the total settlement prevision due to the presence of bleach and washing powder.

scholarly journals Gamification and Hazard Communication in Virtual Reality: A Qualitative Study

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4663
Author(s):  
Janaina Cavalcanti ◽  
Victor Valls ◽  
Manuel Contero ◽  
David Fonseca
Keyword(s):  
Virtual Reality ◽  
New Technologies ◽  
Training Environment ◽  
Hazard Communication ◽  
Head Mounted Display ◽  
Compliance Behavior ◽  
Before And After ◽  
Recorded Data ◽  
The Impact ◽  
Different Levels

An effective warning attracts attention, elicits knowledge, and enables compliance behavior. Game mechanics, which are directly linked to human desires, stand out as training, evaluation, and improvement tools. Immersive virtual reality (VR) facilitates training without risk to participants, evaluates the impact of an incorrect action/decision, and creates a smart training environment. The present study analyzes the user experience in a gamified virtual environment of risks using the HTC Vive head-mounted display. The game was developed in the Unreal game engine and consisted of a walk-through maze composed of evident dangers and different signaling variables while user action data were recorded. To demonstrate which aspects provide better interaction, experience, perception and memory, three different warning configurations (dynamic, static and smart) and two different levels of danger (low and high) were presented. To properly assess the impact of the experience, we conducted a survey about personality and knowledge before and after using the game. We proceeded with the qualitative approach by using questions in a bipolar laddering assessment that was compared with the recorded data during the game. The findings indicate that when users are engaged in VR, they tend to test the consequences of their actions rather than maintaining safety. The results also reveal that textual signal variables are not accessed when users are faced with the stress factor of time. Progress is needed in implementing new technologies for warnings and advance notifications to improve the evaluation of human behavior in virtual environments of high-risk surroundings.

scholarly journals Six ultraviolet minutes for cleaner operating theatres

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
R Bosco ◽  
S Gambelli ◽  
V Urbano ◽  
G Cevenini ◽  
G Messina
Keyword(s):  
Cross Sectional Study ◽  
Cross Sectional ◽  
Before And After ◽  
Operating Theatres ◽  
Cleaning Procedures ◽  
The Difference ◽  
Contamination Levels ◽  
Different Levels ◽  
Better Than ◽  
Final Cleaning

Abstract Background Sanitizing the operating theatres (OT) is important to minimize risk of post-operative infections. Disinfection procedures between one operation and another is less aggressive than final cleaning procedures, at the end of the day. Aim was assessing the difference of contamination: i) between different levels of disinfection; ii) before and after the use of a UVC Device (UVC-D). Methods Between December 2019/February 2020 a cross sectional study was conducted in OT in a real clinical context. 94 Petri dishes (PD) were used in 3 OT. Three different sanitation levels (SL1-3) were compared pre- and post-use of UVC-D: i) No cleaning after surgery (SL1); ii) after in-between cleaning (SL2); iii) after terminal cleaning (SL3). UVC-D was employed for 6 minutes, 3 minutes per bed side. PD were incubated at 36 °C and colony forming unit (CFU) counted at 48h. Descriptive statistic, Wilcoxon and Mann-Whitney tests were performed to assess the contamination levels in total, pre/post use of UVC-D, and between different sanitation levels, respectively. Results In total we had a mean of 3.39 CFU/PD (C.I. 2.05 - 4.74) and a median of 1 CFU/PD (Min. 0 - Max. 39), after UVC-D use we had a mean of 2.20 CFU/PD (C.I. 0.69 - 5.09) and a median of 0 CFU/PD (Min. 0 - Max. 133). The UVC-D led to a significant reduction of CFU (p < 0.001). Without UVC-D we had a significant CFU drop (p < 0.05) between SL1 and SL3. Using UVC-D, we observed significant reductions of contamination (p < 0.05) between SL3 and SL1. Comparing SL1 (median 0) post UVC-D use vs SL2 pre UVC-D use (median 0.5), and SL2 post UVC-D use (median 0) vs SL3 pre UVC-D use (median 1) we had a significant reduction of contamination (p < 0.05). Conclusions UVC-D improved environmental contamination in any of the three sanitation levels. Furthermore, the use of UVC-D alone was better than in-between and terminal cleaning. Although these encouraging results, the cleaning procedures executed by dedicated staff has to be considered. Key messages UVC are efficient to decrease contamination in operating theatres regardless of sanitation levels. The additional use of UVC technology to standard cleaning procedures significantly improves sanitation levels.

How to Compare the Incomparable: An International Comparison of the Impact of Housing Costs on Levels of Social Assistance

2003 ◽  
Vol 5 (2) ◽  
pp. 128-149 ◽  
Author(s):  
Susan Kuivalainen
Keyword(s):  
Social Assistance ◽  
Disposable Income ◽  
The United Kingdom ◽  
Relative Value ◽  
Housing Costs ◽  
Family Types ◽  
Before And After ◽  
The Impact ◽  
Levels Of Support ◽  
Different Levels

This article analyses the importance of housing costs in cross-national comparisons of social assistance. The article explores the model family technique, the most commonly used method of comparing levels of support, and analyses the impact of housing costs on outcomes. The importance of housing costs is assessed by using different definitions of disposable income, by comparing the level of social assistance without, before and after housing costs. Three different rent levels are specified in order to evaluate the impact of housing costs and seven different family types are considered in the analysis. The countries used for comparison are Denmark, Finland, the Netherlands, Sweden, and the United Kingdom, during the late 1990s. The findings show that housing costs have an impact on outcomes in social assistance: when housing costs are disregarded, the differences between countries are greater. The outcomes vary with different calculations of disposable income: the relative value of assistance between countries and families varies, and the ranking of countries is also altered. Different levels of housing costs have a similar impact, showing changes in the relative position of countries. Overall the findings show that taking housing costs into account makes a difference.

scholarly journals State-of-the-Art-Review of Collapsible Soils

2000 ◽  
Vol 5 ◽  
pp. 115 ◽  
Author(s):  
A. A. AL-Rawas
Keyword(s):  
Field Tests ◽  
Clay Content ◽  
Field Testing ◽  
Dry Density ◽  
Foundation Design ◽  
Treatment Methods ◽  
Collapse Potential ◽  
Collapsible Soils ◽  
Different Types ◽  
Compaction Control

Collapsible soils are encountered in arid and semi-arid regions. Such soils cause potential construction problems due to their collapse upon wetting. The collapse phenomenon is primarily related to the open structure of the soil. Several soil collapse classifications based on parameters such as moisture content, dry density, Atterberg limits and clay content have been proposed in the literature as indicators of the soil collapse potential. Direct measurement of the magnitude of collapse, using laboratory and/or field tests, is essential once a soil showed indications of collapse potential. Treatment methods such as soil replacement, compaction control and chemical stabilization showed significant reduction in the settlement of collapsible soils. The design of foundations on collapsible soils depends on the depth of the soil, magnitude of collapse and economics of the design. Strip foundations are commonly used when collapsing soil extends to a shallow depth while piles and drilled piers are recommended in cases where the soil extends to several meters. This paper provides a comprehensive review of collapsible soils. These include the different types of collapsible soils, mechanisms of collapse, identification and classification methods, laboratory and field testing, treatment methods and guidelines for foundation design.

Application of a Novel Collector DXS in Cassiterite Flotation

2013 ◽  
Vol 826 ◽  
pp. 14-19
Author(s):  
Yi Min Zhu ◽  
Yan Ping Yang ◽  
Wen Dan Wang ◽  
Yan Feng Li ◽  
Duo Zhen Ren ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Infrared Spectroscopy ◽  
Carboxylic Acid ◽  
Comparative Study ◽  
Hydroxamic Acid ◽  
Spectroscopy Analysis ◽  
Adsorption Mechanisms ◽  
Before And After ◽  
The Relationship

A comparative study on the collecting effect to cassiterite was studied using a new carboxylic acid modified collector DXS and traditional collector salicylaldehyde hydroxamic acid as collectors, respectively. In addition, the relationship between floatability of DXS and crystal structure of cassiterite was investigated. By means of infrared spectroscopy analysis of the cassiterite surface before and after adsorbing DXS molecules, the adsorption mechanisms of DXS on the surface of cassiterite were analyzed.Keywords: carboxylic acid modified collector DXS; cassiterite; flotation mechanism

PENGARUH KOMUNIKASI TERAPEUTIK TERHADAP PENURUNAN TINGKAT KECEMASAN PASIEN PRE-OPERATIF DI IBS BLU RSUP Prof. Dr. R.D. KANDOU MANADO

e-NERS ◽  
2013 ◽  
Vol 1 (1) ◽  
Author(s):  
Reychie Janis Sanggel ◽  
Jeavery Bawotong ◽  
Gresty Masi
Keyword(s):  
Null Hypothesis ◽  
T Test ◽  
Patient Anxiety ◽  
Therapeutic Communication ◽  
Significance Level ◽  
Paired Samples ◽  
Before And After ◽  
Independent Variable ◽  
Keywords Anxiety ◽  
Different Levels

Abstrak: Dalam menyiapkan pasien yang akan dioperasi, maka perawat dituntut mampu menyiapkan pasien untuk siap menjalani tindakan pembedahan. Sehingga komunikasi terapeutik dapat diterapkan oleh perawat untuk mengurangi kecemasannya. Penelitian ini bertujuan untuk mengetahui pengaruh komunikasi terapeutik terhadap penurunan tingkat kecemasan pasien pre-operatif di IBS BLU RSUP Prof.Dr.R.D.Kandou Manado. Desain dalam penelitian ini adalah pra-eksperiment one group pretest-posttest design. Sampel adalah pasien yang akan menjalani operasi di IBS BLU RSUP Prof.Dr.R.D.Kandou Manado yang mempunyai kecemasan. Variabel independen adalah komunikasi terapeutik dan variabel dependen adalah tingkat kecemasan pasien pre-operatif. Analisa data menggunakan uji-T sampel berpasangan pada tingkat kemaknaan 95% (α ≤0,05) dengan bantuan program SPSS versi 20. Hasil analisa didapatkan nilai p=0,000, artinya p <α. Hal ini berarti hipotesis nol (H0) ditolak. Dengan kata lain terdapat perbedaan tingkat kecemasan sebelum dan sesudah dilakukan komunikasi terapeutik pada pasien pre-operatif di IBS BLU RSUP Prof.Dr.R.D.Kandou Manado. Kata kunci: kecemasan, komunikasi terapeutik, pasien pre-operatif.     Abstract: In preparing the patient to be operated, the nurses are able to prepare patients to readily undergo surgery. So that therapeutic communication can be applied by nurses to reduce anxiety. This study aimed to determine the effect of therapeutic communication to the decline in the level of patient pre-operative anxiety in IBS BLU Dr Prof.Dr.RDKandou Manado. The design in this study were pre-experimental one group pretest-posttest design. Samples are patients who will undergo surgery in the department of Prof.Dr.RDKandou Manado BLU IBS who have anxiety. The independent variable was therapeutic communication and the dependent variable is the level of pre-operative patient anxiety. Analysis of data using paired samples T-test at 95% significance level (α ≤ 0.05) with SPSS version 20. Analysis results obtained p=0.000, meaning that p <α. This means that the null hypothesis (H0) is rejected. In other words, there are different levels of anxiety before and after therapeutic communication in pre-operative patients in the IBS BLU Dr Prof.Dr.RD. Kandou Manado. Keywords: anxiety, therapeutic communication, pre-operative patients.

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