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Abstrakt

The paper concerns the utilization of hydrated lime and zeolites as additives in warm mix asphalt produced with foamed bitumen. The mentioned additives were added to the mixtures in exchange for specific quantities of mineral filler, which amounted to 0.4% and 1.2% of hydrated lime or 0.4% of water-modified and 1.0% of air-dry zeolites in mineral mix. The study investigated warm-produced mixtures with 4.5% and 4.8% binder content and production and compaction temperatures set at 120⁰C and 100⁰C respectively. Additionally, reference hot and warm mixtures were evaluated. The testing included: air void content, indirect tensile strength in dry state and after one freeze-thaw cycle as well as the resulting resistance to moisture and frost damage index. The mixtures incorporating hydrated lime and lower bitumen content of 4.5% exhibited increased air voids and mostly unchanged mechanical performance when compared to the reference warm mix. Increased bitumen content has resulted in significantly improved performance in moisture resistance and compactability which could be compared to that of the reference hot-produced mixture. On the other hand, the incorporation of zeolites in the foamed bitumen mixtures resulted in all cases in increased air void content in the samples. This has apparently led to decreased indirect tensile strength, in both the dry state and after the freeze-thaw cycle. Based on the results it was concluded that the production temperature of the zeolite-bearing mixtures was too low for the zeolite water to significantly improve the mix’ workability and therefore positively affect its mechanical parameters.
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Bibliografia

  1.  A. Chomicz-Kowalska, W. Gardziejczyk, and M.M. Iwański, “Moisture resistance and compactibility of asphalt concrete produced in half- warm mix asphalt technology with foamed bitumen”, Constr. Build. Mater. 126, 108–118 (2016), doi: 10.1016/j.conbuildmat.2016.09.004.
  2.  A. Chomicz-Kowalska, W. Gardziejczyk, and M.M. Iwański, “Analysis of IT-CY Stiffness Modulus of Foamed Bitumen Asphalt Concrete Compacted at 95°C”, Procedia Eng. 172, 550–559 (2017), doi: 10.1016/j.proeng.2017.02.065.
  3.  M.R. Mohd Hasan, Z. You, and X. Yang, “A comprehensive review of theory, development, and implementation of warm mix asphalt using foaming techniques”, Constr. Build. Mater. 152, 115–133 (2017), doi: 10.1016/j.conbuildmat.2017.06.135.
  4.  E. Remišová and M. Holý, “Changes of Properties of Bitumen Binders by Additives Application”, in IOP Conf. Ser.: Mater. Sci. Eng. 245(3), 032003 (2017), doi: 10.1088/1757-899X/245/3/032003.
  5.  M. M. Iwański, A. Chomicz-Kowalska, and K. Maciejewski, “Effect of Surface Active Agent (SAA) on 50/70 Bitumen Foaming Characteristics”, Materials (Basel). 12(21), 3514, (2019), doi: 10.3390/ma12213514.
  6.  O. Larsen, Ø. Moen, C. Robertus, and B.G. Koenders, “WAM Foam asphalt production at lower operating temperatures as an environmental friendly alternative to HMA”, 3rd Eurasphalt Eurobitume Congr., 2004, pp. 641–650. [Online]. Available: http://www.shell.com/content/ dam/shell/static/bitumen/downloads/wam-field-test-resultseurasphaltcongress.pdf.
  7.  A. Chomicz-Kowalska and K. Maciejewski, “Performance and viscoelastic assessment of high-recycle rate cold foamed bitumen mixtures produced with different penetration binders for rehabilitation of deteriorated pavements”, J. Clean. Prod. 258, 120517 (2020), doi: 10.1016/j.jclepro.2020.120517.
  8.  F. Yin, E. Arambula, and D. E. Newcomb, “Effect of water content on binder foaming characteristics and foamed mixture properties”, Transp. Res. Rec. 2506, 1–7 (2015), doi: 10.3141/2506-01.
  9.  K. Maciejewski, “Wpływ rodzaju dodatku i starzenia krótkoterminowego na właściwości wysokotemperaturowe asfaltów drogowych przeznaczonych do mieszanek mineralno-asfaltowych wytwarzanych w technologii „na ciepło” z asfaltem spienionym wodą”, Ph.D Thesis, Kielce University of Technology, Kielce, 2019, [in Polish].
  10.  M. Iwański, G. Mazurek, and P. Buczyński, “Bitumen foaming optimisation process on the basis of rheological properties”, Materials (Basel). 11(10), 1854 (2018), doi: 10.3390/ma11101854.
  11.  A. Chomicz-Kowalska, K. Maciejewski, and M.M. Iwański, “Study of the Simultaneous Utilization of Mechanical Water Foaming and Zeolites and Their Effects on the Properties of Warm Mix Asphalt Concrete”, Materials (Basel). 13(2), 357 (2020), doi: 10.3390/ ma13020357.
  12.  E. Lippmaa, M. Mági, A. Samoson, M. Tarmak, and G. Engelhardt, “Investigation of the Structure of Zeolites by Solid-State High- Resolution 29Si NMR Spectroscopy”, J. Am. Chem. Soc. 103(17), 4992–4996 (1981), doi: 10.1021/ja00407a002.
  13.  A. Sassani, “A Multi-Scale Approach to Characterization of Volcanic Natural Pozzolans”, Middle East Technical University, Ankara, 2014.
  14.  A. Sassani, L. Turanlı, A.-H. Emwas, and Ç. Meral, “Mechanical performance, durability and aluminosilicate chain structure of high volume zeolitic natural pozzolan – portland cement based systems”, in Zeolite 2014 – 9th International Conference on the Occurrence, Properties and Utilization of Natural Zeolites, 2014, pp. 209–201.
  15.  N.Q. Feng and G.F. Peng, “Applications of natural zeolite to construction and building materials in China”, Constr. Build. Mater. 19(8), 579–584 (2005), doi: 10.1016/j.conbuildmat.2005.01.013.
  16.  B. Lai, C. Barros, and H. Yin, “Investigation of rheological behavior of asphalt binder modified by the Advera® additive”, in Poromechanics IV – 4th Biot Conference on Poromechanics, 2009, pp. 487–492.
  17.  A. Woszuk, R. Panek, J. Madej, A. Zofka, and W. Franus, “Mesoporous silica material MCM-41: Novel additive for warm mix asphalts”, Constr. Build. Mater. 183, 270–274 (2018), doi: 10.1016/j.conbuildmat.2018.06.177.
  18.  A. Woszuk and W. Franus, “Properties of the Warm Mix Asphalt involving clinoptilolite and Na-P1 zeolite additives”, Constr. Build. Mater. 114, 556–563 (2016), doi: 10.1016/j.conbuildmat.2016.03.188.
  19.  A. Woszuk and W. Franus, “A review of the application of zeolite materials in warm mix asphalt technologies”, Appl. Sci. 7(3), 293 (2017), doi: 10.3390/APP7030293.
  20.  A. Woszuk, A. Zofka, L. Bandura, and W. Franus, “Effect of zeolite properties on asphalt foaming”, Constr. Build. Mater. 139, 247–255 (2017), doi: 10.1016/j.conbuildmat.2017.02.054.
  21.  D.E. Newcomb et al., “Properties of foamed asphalt for warm mix asphalt applications. NCHRP Report 807”, Washington DC, 2015.
  22.  H. Gong, Y. Sun, W. Hu, P.A. Polaczyk, and B. Huang, “Investigating impacts of asphalt mixture properties on pavement performance using LTPP data through random forests”, Constr. Build. Mater. 204, 203–212 (2019), doi: 10.1016/j.conbuildmat.2019.01.198.
  23.  R. Ghabchi, D. Singh, and M. Zaman, “Laboratory evaluation of stiffness, low-temperature cracking, rutting, moisture damage, and fatigue performance of WMA mixes”, Road Mater. Pavement Des. 16(2), 334–357 (2015), doi: 10.1080/14680629.2014.1000943.
  24.  A. Chomicz-Kowalska, J. Mrugała, and K. Maciejewski, “Evaluation of Foaming Performance of Bitumen Modified with the Addition of Surface Active Agent”, in IOP Conf. Ser.: Mater. Sci. Eng. 245(3), 032086 (2017), doi: 10.1088/1757-899X/245/3/032086.
  25.  J. Komačka and E. Remišová, “Investigation of the Relation between Adhesion and Water Sensitivity Test Results”, Slovak J. Civ. Eng. 27(4), 1–6 (2019), doi: 10.2478/sjce-2019-0024.
  26.  L. Gungat, N. I. M. Yusoff, and M.O. Hamzah, “Effects of RH-WMA additive on rheological properties of high amount reclaimed asphalt binders”, Constr. Build. Mater. 114, 665–672 (2016), doi: 10.1016/j.conbuildmat.2016.03.182.
  27.  M. Stienss and C. Szydlowski, “Influence of Selected Warm Mix Asphalt Additives on Cracking Susceptibility of Asphalt Mixtures”, Materials (Basel). 13(1), 202 (2020), doi: 10.3390/ma13010202.
  28.  K. Kowalski, J. Król, W. Bańkowski, P. Radziszewski, and M. Sarnowski, “Thermal and Fatigue Evaluation of Asphalt Mixtures Containing RAP Treated with a Bio-Agent”, Appl. Sci. 7(3), 216 (2017), doi: 10.3390/app7030216.
  29.  M.M. Iwanski, A. Chomicz-Kowalska, and K. Maciejewski, “Resistance to moisture-induced damage of half-warm-mix asphalt concrete with foamed bitumen”, Materials (Basel). 13(3), 654 (2020), doi: 10.3390/ma13030654.
  30.  A. Chomicz-Kowalska, “Laboratory testing of low temperature asphalt concrete produced in foamed bitumen technology with fiber reinforcement”, Bull. Polish Acad. Sci. Tech. Sci. 65(6), 779‒790 (2017), doi: 10.1515/bpasts-2017-0086.
  31.  C.V. Chachas, W.J. Liddle, D.E. Peterson, and M.L. Wiley, “Use of hydrated lime in bituminous mixtures to decrease hardening of the asphalt cement (Report No. PB 213 170)”, 1971.
  32.  E. Seebaly, P.D.N. Little, and J. A. Epps, The Benefis of Hydrated Lime in Hot Mix Asphalt, The National Lime Association, Arlington, 2006.
  33.  J.C. Petersen, H. Plancher, and P.M. Harnsberger, “Lime Treatment of Asphalt to Reduce Age Hardening and Improve Flow Properties”, Assoc. Asph. Paving Technol. 56–87, 632–653 (1987).
  34.  M. Stroup-Gardiner and J.A. Epps, “Effect of lime on asphalt concrete pavement performance”, in Proceedings of the American Society Civil Engineers Materials Congress, 1990, pp. 921–930.
  35.  F. Luxemburg, “Lime Hydrate as an Additive to Improve the Adhesion of Bitumen to the Aggregates”, in Proc of the II International Conference Durable and Save Road Pavements, 1996, pp. 296–302.
  36.  D. Lesueur, J. Petit, and H. J. Ritter, “The mechanisms of hydrated lime modification of asphalt mixtures: A state-of-the-art review”, Road Mater. Pavement Des. 14(1), 1–16 (2013), doi: 10.1080/14680629.2012.743669.
  37.  M. Iwański, Wapno hydratyzowane wielofunkcyjnym dodatkiem zwiększającym trwałość nawierzchni SMA. Monograph M59. Kielce: Kielce University of Technology, 2014, [in Polish]
  38.  H. Plancher, E.L. Green, and J.C. Petersen, “Reduction of Oxidative Hardening of Asphalts By Treatment With Hydrated Lime – a Mechanistic Study”, in Proc Assoc Asphalt Paving Technol, 1976, vol. 45, pp. 1–24.
  39.  C. Gorkem and B. Sengoz, “Predicting stripping and moisture induced damage of asphalt concrete prepared with polymer modified bitumen and hydrated lime”, Constr. Build. Mater. 23(6), 2227–2236 (2009), doi: 10.1016/j.conbuildmat.2008.12.001.
  40.  M.M. Iwański, “Synergia wapna hydratyzowanego i asfaltu spienionego w zapewnieniu trwałości eksploatacyjnej betonu asfaltowego w technologii na półciepło”, Ph.D Thesis, Politechnika Świętokrzyska, 2019.
  41.  M. Kadela, “Model of multiple-layer pavement structure-subsoil system”, Bull. Polish Acad. Sci. Tech. Sci. 64(4), 751–762 (2016), doi: 10.1515/bpasts-2016-0084.
  42.  EN 13108-1:2008. Bituminous mixtures. Material specifications. Asphalt Concrete.
  43.  WT-2 2014. Asphalt mixes. Technical Requirements. Appendix to ordinance No. 54 of the General Director of National Roads and Highways, 8.11.2014, 2014.
  44.  EN 12591:2009. Bitumen and bituminous binders. Specifications for paving grade bitumens.
  45.  WT-1 2014. Aggregates for Asphalt Mixes and Surface Dressings on National Highways. Technical Requirements. Appendix to ordinance No. 46 of the General Director of National Roads and Highways, 25.09.2014, [Online]. Available: www.gddkia.gov.pl.
  46.  E. Szewczak, A. Winkler-Skalna, and L. Czarnecki, “Sustainable Test Methods for Construction Materials and Elements”, Materials (Basel). 13(3), 606 (2020), doi: 10.3390/ma13030606.
  47.  A. Chomicz-Kowalska and K. Maciejewski, “Multivariate optimization of recycled road base cold mixtures with foamed bitumen”, Procedia Eng. 108, 436–444 (2015), doi: 10.1016/j.proeng.2015.06.168.
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Autorzy i Afiliacje

Anna Chomicz-Kowalska
1
ORCID: ORCID
Krzysztof Maciejewski
1
ORCID: ORCID
Mateusz Marek Iwański
1
ORCID: ORCID
Karolina Janus
1
ORCID: ORCID

  1. Kielce University of Technology, al. Tysiąclecia Państwa Polskiego 7, 25-314 Kielce, Poland
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Abstrakt

Sodium silicate is one of the most successful inorganic binder. Along with the broad application of sodium silicate for domestic and industrial purposes, the composition analysis, include modulus (m), ratio of SiO2:Na2O, Na2O%, SiO2%, and solid-containing content, is important for the products strength and service life. However, it is perplexing to operate, inefficient and low precision for traditional standard testing method of these parameters. In this study, an automatic measurement system of sodium silicate composition analysis, with the potential electrode for potentiometer titration, micro-controller, PCB, heater, stirrer, printer and micro peristaltic pump, was developed according to the determine method principle. The end-points of pH value in the two titrating steps, first was 4.3 and second was 6.0, were set in the micro-controller to control the reaction in the processing of the sodium silicate composition analysis. And all the potential signals of the pH electrode were transited in the special PCB for the micro-controller.
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Bibliografia

[1] Rabbii, A. (2001). Sodium silicate glass as an inorganic binder in foundry industry. Iranian Polymer Journal. 10(4), 229-235.
[2] Stachowicz, M., Pałyga, Ł.& Kȩpowicz, D. (2020). Influence of automatic core shooting parameters in hot-box technology on the strength of sodium silicate olivine moulding sands. Archives of Foundry Engineering. 20(1), 67-72.
[3] Huafang, W., Wenbang, G. & Jijun, L. (2014). Improve the humidity resistance of sodium silicate sands by estermicrowave composite hardening. Metalurgija. 53(4), 455-458.
[4] Nowak, D. (2017). The impact of microwave penetration depth on the process of heating the moulding sand with sodium silicate. Archives of Foundry Engineering. 17(4), 115-118.
[5] M. Stachowicz, K. Granat, & D. Nowak. (2011). Application of microwaves for innovative hardening of environment-friendly water-glass moulding sands used in manufacture of cast-steel castings. Archives of Civil and Mechanical Engineering. XI(1), 209-219.
[6] Zhu, CX. (2007). Recent advances in waterglass sand technologies. China Foundry. 4(1), 13-17.
[7] Masuda Yuki, Tsubota Keiji, Ishii Kenichi, Imakoma Hironobu, Ohmura Naoto. (2009) Drying rate and surface temperature in solidification of glass particle layer with inorganic binder by microwave drying. Kagaku Kogaku Ronbunshu. 35(2). 229-231.
[8] Standardization Administration of the P.R.C. (2008). GB/T4209-2008, Sodium silicate for industry use[S]. Beijing, China Standard Press.
[9] Bourikas K., Kordulis C. & Lycourghiotis A. (2005). Differential potentiometric titration: Development of a methodology for determining the point of zero charge of metal (Hydr)oxides by one titration curve. Environmental Science & Technology. 39(11), 4100-4108.
[10] Fan ZT, Liu M, Wang HF, Long W, Hu XT. (2010). Chinese Patent No. 201010558029.3. Beijing, China National Intellectual Property Administration.
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Autorzy i Afiliacje

Huafang Wang
1
ORCID: ORCID
Quanrun Wang
1
Wu Zhang
1
Xiang Gao
1
Jijun Lu
1
ORCID: ORCID

  1. School of Mechanical Engineering and Automation, Wuhan Textile University, Wuhan 430073, China

Abstrakt

The Euler multiphase flow and population equilibrium model were used to simulate the three-phase flow field in the bubble expansion stage of the outlet curved pipe section. The influence of the ratio of the bending diameter and the volume fraction of the gas phase on the pressure loss is revealed, and the safety range of the optimum bending diameter ratio and the volume fraction of the outlet gas phase is determined. The results show that the three-phase flow in the tube is more uniformly distributed in the vertical stage, and when the pipe is curved, the liquid-phase close to the pipe wall gathers along the pipe flank to the outside of the pipe, the solid phase is transferred along the pipe flank to the inside of the pipe, and the gas phase shrinks along the pipe flank to the inner centre. The maximum speed of each phase of the three-phase flow in the elbow is at the wall of the tube from 45° to 60° inside the elbow, and the distribution law along the axial direction of the pipe is about the same as the distribution law of volume fraction. The pressure loss of the elbow decreases with the increase of the bend diameter ratio, when the bend diameter ratio increases to 6, the pressure loss of the pipe decreases sharply, and the pressure loss decreases slowly with the increase of the bend diameter ratio. When the gas phase volume score in the elbow reaches 70%, there will be an obvious wall separation phenomenon, to keep the system in a stable working state and prevent blowout, the gas phase volume score should be controlled within 60%.
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Autorzy i Afiliacje

Wei Chen
1 2 3
ORCID: ORCID
Hai-liang Xu
2 3
ORCID: ORCID
Bo Wu
2 3
ORCID: ORCID
Fang-qiong Yang
2 3
ORCID: ORCID

  1. Hunan University of Humanities, Department of Energy and Electrical Engineering, Science and Technology, Loudi, Hunan 417000, China
  2. Central South University, School of Mechanical and Electrical Engineering, Changsha, Hunan 410083, China
  3. State Key Laboratory of High Performance Complex Manufacturing, Changsha, Hunan 410083, China

Abstrakt

The purpose of the study was to assess the impact of industrial wastewater on the concentration of methanol in the considered section of the Ob River basin, present proposals for the implementation of a new treatment system and analyse the implementation results. On the basis of the results of the analysis of the known methods for reducing the concentration of methanol in water, a new technological scheme for post-treatment of effluents using biological treatment with methylotrophic Methylomonas methanica Dg bacteria was proposed. The calculation of the dilution of treated wastewater using the “NDS Ecolog” program was carried out on the basis of the detailed calculation method of Karaushev, the results of which showed a decrease in the concentration of methanol in the control section to 0.0954 mg∙dm –3 (permissible concentration is 0.1 mg∙dm –3). During the period of the flood of the Glukhaya channel, it ceases to be a separate water body and, in fact, becomes part of the flood channel of the Ob River. Certain parts of the flooded areas, due to elevation changes, communicate with the channel only during a short period of time when the water level rises, i.e. 3–5 weeks during the flood period, and in fact remain isolated reservoirs for the rest of the time, potentially acting as zones of accumulation and concentration of pollutants.
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Autorzy i Afiliacje

Andrey Ivanov
1
ORCID: ORCID
Alexey Strizhenok
1
ORCID: ORCID
Gabriel Borowski
2
ORCID: ORCID

  1. Saint-Petersburg Mining University, Faculty of Mining Engineering, 21st Line of Vasilyevsky island, 2, 199106, Saint-Petersburg, Russia
  2. Lublin University of Technology, Faculty of Environmental Engineering, Poland

Abstrakt

Allergic skin diseases in cats are amongst the most prevalent dermatological conditions in this species. The objectives of this study were to evaluate different types of skin barrier measurements in healthy cats and cats with non-flea non-food hypersensitivity dermatitis (NFNFHD). 24 clinically healthy and 19 NFNFHD cats were included in this clinical trial. In each animal, the transepidermal water loss (TEWL) and skin hydration (SH) were assessed on six clipped body sites by VapoMeter SWL 4605 and Corneometer ®CM 825, respectively. Results of TEWL measurement were , significantly higher in one of the six examined body sites, namely on the lumbar area (p=0.0049). Furthermore, a statistically significant difference was found between the average TEWL values (p=0.019). Statistically notable differences were mea- sured at least in one certain body site for SH: in the groin (p=0.02), where the values in the affect- ed cats were lower than in the healthy individuals. These results may suggest that in NFNFHD cats transepidermal water loss is higher than in healthy cats. Skin hydration is, at least, in certain body sites, lower in atopic feline patients than in healthy individuals.

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Autorzy i Afiliacje

M.P. Szczepanik
P.M. Wilkołek
Ł.R. Adamek
G. Kalisz
M. Gołyński
W. Sitkowski
I. Taszkun

Abstrakt

The ablation casting technology consists in pouring castings in single-use moulds made from the mixture of sand and water-soluble binder. After pouring the mould with liquid metal the mould is destructed (washed out) using a stream of cooling medium, which in this case is water. The process takes place while the casting is still solidifying.

The following paper focuses on testing the influence of the modified ablation casting of aluminum alloy on casts properties produced in moulds with hydrated sodium silicate binder. The authors showed that the best kind of moulding sands for Al alloy casting will be those hardened with physical factors – through dehydration. The analysis of literature data and own research have shown that the moulding sand with hydrated sodium silicate hardened by dehydration is characterized by sufficient strength properties for the modified ablation casting of Al alloys. In the paper the use of microwave hardened moulding sands has been proposed.

The moulds were prepared in the matrix specially designed for this technology. Two castings from the AlSi7Mg alloy were made; one by traditional gravity casting and the other by gravity casting using ablation.

The conducted casts tests showed that the casting made in modified ablation casting technology characterizes by higher mechanical properties than the casting made in traditional casting technology. In both experimental castings the directional solidification was observed, however in casting made by ablation casting, dimensions of dendrites in the structure at appropriate levels were smaller.

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Autorzy i Afiliacje

K. Major-Gabryś
ORCID: ORCID
M. Hosadyna-Kondracka
ORCID: ORCID
S. Puzio
ORCID: ORCID
J. Kamińska
ORCID: ORCID
M. Angrecki
ORCID: ORCID

Abstrakt

New approach using direct crack width calculations of the minimum reinforcement in tensile RC elements is presented. Verification involves checking whether the provided reinforcement ensures that the crack width that may result from the thermal-shrinkage effects does not exceed the limit value. The Eurocode provisions were enriched with addendums derived from the German national annex. Three levels of accuracy of the analysis were defined - the higher the level applied, the more significant reduction in the amount of reinforcement required can be achieved. A methodology of determining the minimum reinforcement for crack width control on the example of a RC retaining wall is presented. In the analysis the influence of residual and restraint stresses caused by hydration heat release and shrinkage was considered.

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Autorzy i Afiliacje

M. Knauff
B. Grzeszykowski
A. Golubińska

Abstrakt

The physical and chemical properties of cements with slag originated from the storage yards of different age, added as a supplementary cementing material are highlighted. The materials after 20-year storage, the crushed slag after approximately 2-year storage and the new slag from the ongoing production were compared. The materials supplied by the same metallurgical plant were characterized. The blended cements were produced by Portland cement clinker grinding with gypsum and slags added as 5 to 50% of binder mass. The standard properties of cements were examined, as well as some experiments related to the kinetics of hydration and hydration products were carried out. The addition of granulated blast furnace slag (GBFS) stored for a long time, as a component of cement, affects the properties of material in such a way that the early compressive strength is not specially altered but at longer maturing the strength decreases generally with the storage time and percentage of additive. This is related to the reduction of the vitreous component, as well as to the presence of weathered material of altered activity. At the additive content up to 50% the binder complying with the requirements of the European standards for CEM III/A or CEM II/(A,B)-S common cements can be produced. The cements with the old slag meet the requirements of EN 197-1 relating at least to the class 32,5. The role of calcium carbonate, being the product resulting from the slag weathering process, acting as a grindability and setting/hardening modifying agent, should be underlined.

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Autorzy i Afiliacje

Wiktor Pacierpnik
Wiesława Nocuń-Wczelik
Ewa Kapeluszna

Abstrakt

In the paper, an indirect method for the identification of the final shape of the freshly executed jet-grouted column is developed. The method relies on the backward analysis of the temperatures measured inside the column, along the trace of the injecting pipe. Temperature changes in the column are caused by the hydration process of the cementitious grout. 2D axisymmetric unsteady heat conduction initial-boundary value problem is solved for finding the column shape which fits best the reference temperature measurements. The model of the column is solved using the finite element method. The search is performed using the global evolutionary optimization algorithm called differential evolution. It is shown that the proposed method can provide an accurate prediction of the column shape if only the model reflects the physical reality well. The advantage over previous results is that the cylindrical shape of the column does not have to be assumed anymore, and the full profile of the column along its length can be accurately identified.
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Autorzy i Afiliacje

Marek Wojciechowski
1
ORCID: ORCID

  1. Lodz University of Technology, Faculty of Civil Engineering, Architecture and Environmental Engineering, Al. Politechniki 6, 90-924 Łódz, Poland

Abstrakt

A mechanistic exposure experiment was performed on the commercially available and welded Ni-Cr-Mo-Fe alloy samples used in the piping materials of the coal gasification pilot plant. Thermodynamic Ellingham-Pourbaix stability diagrams were constructed to provide insight into the mechanism of the observed corrosion behavior. The thermodynamic inference on the corrosion mechanism was supplemented with the morphological, compositional and microstructural analyses of the exposed samples using scanning electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy analyses. X-ray diffraction result revealed stable corrosion products of NiO, MoNi4 and Cr4.6MoNi2.1 after accumulated total exposure duration of 139 h to the corrosive atmosphere. Scanning electron microscopy and energy-dispersive X-ray spectroscopy positively identified formation of rather continuous and adherent pre-oxidation corrosion products although extensively peeled-off oxides were finally observed as corrosion scales on the post-exposure alloy samples, which were attributed to the chlorination/oxidation into thin (spalled) oxides.

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Autorzy i Afiliacje

Sungkyu Lee
Min Jung Kim
Nuri Choi
Sang Yeon Hwang
Seok-Woo Chung
Seung-Jong Lee
Yongseung Yun

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