scholarly journals Effects of Biostabilization on Engineering Properties of Geomaterials

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Shengting Li ◽  
Chenyi Luo ◽  
Yi Yang ◽  
Lvzhen Yang ◽  
Lijian Wu ◽  
...  
Keyword(s):  
Pore Space ◽  
Particle Surface ◽  
Road Construction ◽  
Engineering Properties ◽  
Future Research ◽  
Unconfined Compression ◽  
Bacillus Pasteurii ◽  
Strength Performance ◽  
X Ray ◽  
Compression Sample

Biostabilization is a newly proposed method to improve the strength and durability of geomaterials, and it can serve as an alternative to chemical and mechanical stabilization. The objectives of this study are to perform biostabilization treatments for selected roadway construction geomaterials and to evaluate the biostabilization effects on engineering properties of the geomaterials. Three types of geomaterials were selected, and two of them were compacted soil from unpaved road surface. Bacillus pasteurii, the biostabilization bacterium, was used to induce mineral precipitates within the geomaterial pore spaces, where the biostabilization effects were performed. Two types of liquid incubation media, containing NH4Cl or (NH4)2 SO4, were applied for bacteria culturing. Unconfined compression, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) measurements were conducted to evaluate the biostabilization results. From unconfined compression, sample strength performance was improved by the biostabilization treatments; the benefits of biostabilization were pronounced by a relatively long culturing time and an oven-dry procedure; the liquid culturing medium containing NH4Cl performed better than the medium containing (NH4)2 SO4. After biostabilization, SEM photographs provided direct evidence for the precipitates induced by bacteria within the geomaterial pore space. The precipitates either connected the adjoined particles or partially covered the particle surface, which increased the surface roughness. EDS and XRD results indicated that calcite, dolomite, and albite were the major precipitates produced during biostabilization treatments. In conclusion, biostabilization ameliorated the microstructures of the geomaterials and improved their strength. Future research topics should include the applications of biostabilization for in situ road construction.

scholarly journals Chemical Stabilization of Black Cotton Clay and Laterite Soil Using Drycon Powder for Suitability as Construction Materials

2020 ◽  
pp. 29-39
Author(s):  
Larry Pax Chegbeleh ◽  
Frank Siaw Ackah
Keyword(s):  
Construction Material ◽  
Construction Materials ◽  
Road Construction ◽  
Atterberg Limits ◽  
Engineering Properties ◽  
X Ray Diffraction ◽  
Laterite Soil ◽  
X Ray ◽  
Significant Strength ◽  
Problem Soils

This paper used drycon powder (DP) as stabilization additive for improving the engineering properties of problem soils, specifically, black cotton clay (BCC) and laterite soil (LS), for use as a road construction material. The study was carried out in some parts of the Greater Accra Region of Ghana, through the conduction of index properties tests such as gradation, Atterberg limits, California bearing ratio (CBR), Compaction characteristics and X-ray diffraction (XRD) on the problem soils. CBR, Atterberg limits and environmental quality tests were specifically conducted on DP stabilized soils for comparative analysis. Gradation results revealed 38% fines for BCC and 14% fines for LS. X-ray diffraction analysis revealed the presence of quartz and montmorillonite in BCC, and quartz and kaolinite in LS. Generally, the results of the various tests conducted revealed that DP has the potential of improving the engineering properties of problem soils with significant strength improvement. It can also be inferred from the results that, DP is environmental friendly soil stabilizer.

scholarly journals Strength Performance and Microstructure of Calcium Sulfoaluminate Cement-Stabilized Soft Soil

2021 ◽  
Vol 13 (4) ◽  
pp. 2295
Author(s):  
Hailong Liu ◽  
Jiuye Zhao ◽  
Yu Wang ◽  
Nangai Yi ◽  
Chunyi Cui
Keyword(s):  
Soft Soil ◽  
Hydration Product ◽  
X Ray Diffraction ◽  
Calcium Sulfoaluminate Cement ◽  
Strength Performance ◽  
X Ray ◽  
Calcium Sulfoaluminate ◽  
Stabilized Soil ◽  
Calcium Silicates ◽  
Hydrated Calcium

Calcium sulfoaluminate cement (CSA) was used to stabilize a type of marine soft soil in Dalian China. Unconfined compressive strength (UCS) of CSA-stabilized soil was tested and compared to ordinary Portland cement (OPC); meanwhile the influence of amounts of gypsum in CSA and cement contents in stabilized soils on the strength of stabilized soils were investigated. X-ray diffraction (XRD) tests were employed to detect generated hydration products, and scanning electron microscopy (SEM) was conducted to analyze microstructures of CSA-stabilized soils. The results showed that UCS of CSA-stabilized soils at 1, 3, and 28 d firstly increased and then decreased with contents of gypsum increasing from 0 to 40 wt.%, and CSA-stabilized soils exhibited the highest UCS when the content of gypsum equaled 25 wt.%. When the mixing amounts of OPC and CSA were the same, CSA-stabilized soils had a significantly higher early strength (1 and 3 d) than OPC. For CSA-stabilized soil with 0 wt.% gypsum, monosulfate (AFm) was detected as a major hydration product. As for CSA-stabilized soil with certain amounts of gypsum, the intensity of ettringite (Aft) was significantly higher than that in the sample hydrating without gypsum, but a tiny peak of AFm also could be detected in the sample with 15 wt.% gypsum at 28 d. Additionally, the intensity of AFt increased with the contents of gypsum increasing from 0 to 25 wt.%. When contents of gypsum increased from 25 to 40 wt.%, the intensity of AFt tended to decrease slightly, and residual gypsum could be detected in the sample with 40 wt.% gypsum at 28 d. In the microstructure of OPC-stabilized soils, hexagonal plate-shaped calcium hydroxide (CH) constituted skeleton structures, and clusters of hydrated calcium silicates (C-S-H) gel adhered to particles of soils. In the microstructure of CSA-stabilized soils, AFt constituted skeleton structures, and the crystalline sizes of ettringite increased with contents of gypsum increasing; meanwhile, clusters of the aluminum hydroxide (AH3) phase could be observed to adhere to particles of soils and strengthen the interaction.

scholarly journals Ionic and non-ionic intravenous X-ray contrast media: antibacterial agents?

2021 ◽  
pp. 028418512110198
Author(s):  
Frank Mosler ◽  
Johannes K Richter ◽  
Marc Schindewolf ◽  
Nando Mertineit ◽  
Hendrik von Tengg-Kobligk ◽  
...  
Keyword(s):  
Contrast Media ◽  
Bactericidal Effect ◽  
Future Research ◽  
Inhibitory Effects ◽  
X Ray ◽  
Percutaneous Abscess Drainage ◽  
Ionic Contrast ◽  
Bactericidal Effects ◽  
Free Iodine ◽  
The Subject

X-ray contrast media have been reported to have inhibitory effects on bacterial growth. Despite its potentially beneficial effect on patients, these features of contrast media have received relatively little attention in the medical literature in the past decades. The aim of this review is to evaluate the literature concerning the bactericidal and bacteriostatic effects of X-ray contrast media, specifically if there is a known difference concerning these effects between ionic and non-ionic contrast media. Systematic literature review was performed for the years of publication between 1911 and 2019. Since the publication of Grossich in 1911, the effect of iodine on the treatment of superficial infections in surgical procedures has been established clinical knowledge. Bacteriostatic and bactericidal effects of ionic X-ray contrast media are well established. However, non-ionic contrast agents have been the subject of little research in this respect. In past decades, the hypothesis emerged in the literature that mainly the concentration of free iodine might be responsible for any bacteriostatic or bactericidal effect of ionic X-ray contrast media. Nowadays, however, only non-ionic contrast media are used. The question regarding the mechanism and magnitude of bacteriostatic or bactericidal effects of these, non-ionic contrast media, could not be answered conclusively from this review. Non-ionic contrast media could be used intentionally when a local antibacterial effect is intended (e.g. in percutaneous abscess drainage), as well as to reduce the overall dose of antibiotics administered to a patient. Thus, this question remains relevant and might constitute the area of future research.

scholarly journals Influential Factors and Evaluation Methods of the Performance of Grouted Semi-Flexible Pavement (GSP)—A Review

2021 ◽  
Vol 11 (15) ◽  
pp. 6700
Author(s):  
Xiaogang Guo ◽  
Peiwen Hao
Keyword(s):  
Literature Review ◽  
Systematic Literature Review ◽  
Asphalt Concrete ◽  
Cement Mortar ◽  
Road Construction ◽  
Flexible Pavement ◽  
Evaluation Methods ◽  
Influential Factors ◽  
Future Research ◽  
Relative Evaluation

Grouted Semi-flexible Pavement (GSP) is a novel pavement composed of open-graded asphalt concrete grouted with high-fluidity cement mortar. Due to its excellent load-bearing and anti-rutting performance, it has great potential as anti-rutting overlay and surface in road construction. However, the understanding of GSP performance remains limited and pertinent findings are inconsistent. This article aims to provide a systematic literature review for the articles which were published between 2000 and 2020 on GSP, explore the problems in the recent research, identify knowledge gaps, and deliver recommendations for future research. The influential factors and the relative evaluation methods of GSP performance are summarized and discussed in this article.

scholarly journals Removal of hexavalent chromium from wastewater by Cu/Fe bimetallic nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jien Ye ◽  
Yi Wang ◽  
Qiao Xu ◽  
Hanxin Wu ◽  
Jianhao Tong ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Particle Surface ◽  
Zerovalent Iron ◽  
Order Model ◽  
X Ray ◽  
Nanoscale Zerovalent Iron

AbstractPassivation of nanoscale zerovalent iron hinders its efficiency in water treatment, and loading another catalytic metal has been found to improve the efficiency significantly. In this study, Cu/Fe bimetallic nanoparticles were prepared by liquid-phase chemical reduction for removal of hexavalent chromium (Cr(VI)) from wastewater. Synthesized bimetallic nanoparticles were characterized by transmission electron microscopy, Brunauer–Emmet–Teller isotherm, and X-ray diffraction. The results showed that Cu loading can significantly enhance the removal efficiency of Cr(VI) by 29.3% to 84.0%, and the optimal Cu loading rate was 3% (wt%). The removal efficiency decreased with increasing initial pH and Cr(VI) concentration. The removal of Cr(VI) was better fitted by pseudo-second-order model than pseudo-first-order model. Thermodynamic analysis revealed that the Cr(VI) removal was spontaneous and endothermic, and the increase of reaction temperature facilitated the process. X-ray photoelectron spectroscopy (XPS) analysis indicated that Cr(VI) was completely reduced to Cr(III) and precipitated on the particle surface as hydroxylated Cr(OH)3 and CrxFe1−x(OH)3 coprecipitation. Our work could be beneficial for the application of iron-based nanomaterials in remediation of wastewater.

scholarly journals Review of the relationship between aggregates geology and Los Angeles and micro-Deval tests

2021 ◽  
Vol 80 (3) ◽  
pp. 1963-1980
Author(s):  
Solomon Adomako ◽  
Christian John Engelsen ◽  
Rein Terje Thorstensen ◽  
Diego Maria Barbieri
Keyword(s):  
Los Angeles ◽  
Crystal Size ◽  
Grain Shape ◽  
Mechanical Performance ◽  
Pore Space ◽  
Construction Material ◽  
Engineering Properties ◽  
Coarse Grained ◽  
The Impact ◽  
The Relationship

AbstractRock aggregates constitute the enormous volume of inert construction material used around the globe. The petrologic description as igneous, sedimentary, and metamorphic types establishes the intrinsic formation pattern of the parent rock. The engineering properties of these rocks vary due to the differences in the transformation process (e.g. hydrothermal deposits) and weathering effect. The two most common mechanical tests used to investigate the performance of aggregates are the Los Angeles (LA) and micro-Deval (MD) tests. This study reviewed the geological parameters (including mineralogy, grain and crystal size, grain shape, and porosity) and the relationship to Los Angeles and micro-Deval tests. It was found that high content of primary minerals in rocks (e.g. quartz and feldspar) is a significant parameter for performance evaluation. Traces of secondary and accessory minerals also affect the performance of rocks, although in many cases it is based on the percentage. Furthermore, some studies showed that the effect of mineralogic composition on mechanical strength is not sufficient to draw final conclusions of mechanical performance; therefore, the impact of other textural characteristics should be considered. The disposition of grain size and crystal size (e.g. as result of lithification) showed that rocks composed of fine-grain textural composition of ≤ 1 mm enhanced fragmentation and wear resistance than medium and coarse grained (≥ 1 mm). The effect of grain shape was based on convex and concave shapes and flat and elongated apexes of tested samples. The equidimensional form descriptor of rocks somehow improved resistance to impact from LA than highly flat and elongated particles. Lastly, the distribution of pore space investigated by means of the saturation method mostly showed moderate (R = 0.50) to strong (R = 0.90) and positive correlations to LA and MD tests.

A Review of Process Tomography Application in Inspection System

2014 ◽  
Vol 70 (3) ◽  
Author(s):  
Yasmin Abdul Wahab ◽  
Ruzairi Abdul Rahim ◽  
Mohd Hafiz Fazlul Rahiman ◽  
Herlina Abdul Rahim ◽  
Suzanna Ridzuan Aw ◽  
...  
Keyword(s):  
Electrical Impedance ◽  
Optical Tomography ◽  
Good Condition ◽  
Future Research ◽  
Inspection System ◽  
Ultrasonic Tomography ◽  
Impedance Tomography ◽  
X Ray ◽  
Process Tomography ◽  
Non Destructive

The inspection system is crucial to ensure the system is always in a good condition. A technique that can be used for inspection system is process tomography. By promising non-destructive approach; various types of process tomography applied in civil, manufacturing and electrical applications. The purpose of this paper is to review the types of process tomography such as ultrasonic tomography, x-ray tomography, optical tomography, electrical resistance tomography, and electrical impedance tomography that had been applied to the inspection system. Variety techniques of inspection based on those sensors briefly discussed in this paper. The result showed that the process tomography expanded tremendously in the inspection system. Finally, a potential future research on the inspection system in the civil application proposed in this paper.

scholarly journals A review of Waste Tyre Rubber as an Alternative Concrete Consituent Material

2018 ◽  
Vol 199 ◽  
pp. 11003 ◽  
Author(s):  
Kudzai Mushunje ◽  
Mike Otieno ◽  
Yunus Ballim
Keyword(s):  
Health And Safety ◽  
Engineering Properties ◽  
Future Research ◽  
Rubber Material ◽  
Safety Risks ◽  
Concrete Production ◽  
Potential Benefits ◽  
Waste Tyre ◽  
Health And Safety Risks ◽  
Published Research

The current global waste tyre generation far exceeds its consumption in terms of recycling and re-use. The traditional recycling and re-use methods like thermal incineration have proven ineffective, costly and in some cases environmentally unsustainable. Particularly, in developing countries where some of the sophisticated techniques required to process tyres to allow them to be utilised are either too costly or have not yet been developed. The situation has resulted in accumulation of large waste tyre stockpiles that pose health and safety risks. To combat the problem, the use of waste tyre rubber in concrete construction has been proposed. Several studies have been conducted to assess the effects of the inclusion of waste tyre rubber in its different forms (fibres, particles), for concrete production and the results are promising. Although there are some apparent demerits to the inclusion of tyre rubber in concrete, the potential benefits seem to overshadow the negatives. This paper reviews published research on the scientific and technical viability of using waste tyre rubber in concrete production. It discusses the production and properties of waste tyre particles. It highlights advances made with regards to the incorporation of tyre rubber material in concrete, focusing on the engineering properties of the tyre rubber modified concrete. In conclusion, recommendations for future research and possible application for the material will be discussed.

Structural aspects of the hisingerite-neotocite series

Clay Minerals ◽  
1983 ◽  
Vol 18 (1) ◽  
pp. 21-31 ◽  
Author(s):  
R. A. Eggleton ◽  
J. H. Pennington ◽  
R. S. Freeman ◽  
I. M. Threadgold
Keyword(s):  
Function Analysis ◽  
Pore Space ◽  
Hollow Spheres ◽  
X Ray ◽  
Broken Hill ◽  
Transmission Electron ◽  
X Ray Absorption ◽  
Interconnected Pore ◽  
Intermediate Member ◽  
Structural Aspects

AbstractTransmission electron microscopy, X-ray radial distribution function analysis, chemical analysis, X-ray absorption edge spectroscopy, and Mössbauer spectroscopy combine to confirm an amorphous or gel structure for minerals of the hisingerite-neotocite series: (Fe,Mn)0.8SiO3.1.2H2O. A framework of (Fe,Mn)O6 octahedra and [SiO4] tetrahedra form hollow spheres, 50–100 Å in diameter, cross-bonded into a physically isotropic solid with as much as 10% interconnected pore space. The outer 10–20 Å of the spheres has a rudimentary structure, possibly marking the onset of segregation into Si-rich and (Fe,Mn)-rich layers. The Broken Hill mineral ‘sturtite’ is an intermediate member of the hisingerite-neotocite series.

scholarly journals The Use of Calcium Lactate to Enhance the Durability and Engineering Properties of Bioconcrete

2021 ◽  
Vol 13 (16) ◽  
pp. 9269
Author(s):  
Saddam Hussein Abo Sabah ◽  
Luis Hii Anneza ◽  
Mohd Irwan Juki ◽  
Hisham Alabduljabbar ◽  
Norzila Othman ◽  
...  
Keyword(s):  
Calcium Lactate ◽  
Engineering Properties ◽  
Optimal Conditions ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Sem Images ◽  
X Ray ◽  
Predicted Values ◽  
Potential Option ◽  
Scanning Electron

This study investigated the optimization of the bioconcrete engineering properties and durability as a response of the calcium lactate (CL) content (0.22–2.18 g/L) and curing duration (7–28 days) using the response surface methodology (RSM). Scanning electronic microscopy (SEM) was conducted to evaluate the microstructure of calcium precipitated inside the bioconcrete. The results indicated that the optimal conditions for the engineering properties of concrete and durability were determined at 2.18 g/L of CL content after 23.4 days. The actual and predicted values of the compressive strength, splitting tensile strength, flexural strength, and water absorption were 43.51 vs. 43.43, 3.19 vs. 3.19, 6.93 vs. 5.50, and 7.55 vs. 7.55, respectively, with a level of confidence exceeding 95%. The scanning electron microscope (SEM) images and energy-dispersive X-ray spectroscopy (EDX) proved that the amount of calcium increased with the increase in CL content up to 2.81 g/L at 23.4 days, reducing the pores inside the concrete and making it a great potential option for healing of concrete structures.

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