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Number of results: 22
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Abstract

Self-curing concrete SC is a concrete type that can be cured without using any external curing regimes. It can perform by several methods such as using lightweight aggregate or chemical agents. In this research chemical curing agent is used to produce SC. This paper reports the results of a research study conducted to evaluate the effect of sulfates on the performance of self-curing concrete compared to ordinary concrete. Samples are immersed in sodium sulfate Na2S04 solution of 4% concentration. Results are measured in terms of compressive strength, tensile strength, flexural strength and mass loss. It was found that the rate of strength loss is noticed at ordinary concrete compared to SC concrete. Sulfate resistance is improved when using self-curing concrete. This improvement appears to be dependent on using a chemical curing agent.

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Authors and Affiliations

A.A. Bashandy
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Abstract

The organo-inorganic commercial binder Albertine F/1 (Hüttenes-Albertus) constituting the starch-aluminosilicate mixture was directed to structural studies. The paper presents a detailed structural analysis of the binder before and after exposure to physical curing agents (microwaves, high temperature) based on the results of infrared spectroscopy studies (FTIR). An analysis of structural changes taking place in the binder system with the quartz matrix was also carried out. Based on the course of the obtained IR spectra, it was found that during the exposure on physical agents there are structural changes within the hydroxyl groups in the polymeric starch chains and silanol groups derived from aluminosilicate as well as in the quartz matrix (SiO2). The curing of the molding sand takes place due to the evaporation of the solvent water and the formation of intramolecular and intermolecular cross-linking hydrogen bonds. Type and amount of hydrogen bonds presence in cured molding sand have an impact on selected properties of molding sand. Results indicates that for molding sand with Albertine F/1 during conventional heating a more extensive network of hydrogen bonds is created.
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Authors and Affiliations

S. Żymankowska-Kumon
B. Grabowska
A. Bobrowski
K. Kaczmarska
S. Cukrowicz
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Abstract

A study was undertaken to investigate the effects of crumb rubber on the strength and mechanical behaviour of Rubberized cement soil (RCS). In the present investigation, 26 groups of soil samples were prepared at five different percentages of crumb rubber content, four different percentages of cement content and two different finenesses of crumb rubber particle. Compressive strength tests were carried out at the curing age of 7 days, 14 days, 28 days and 90 days. The test results indicated that the inclusion of crumb rubber within cement soil leads to a decrease in the compressive strength and stiffness and improves the cement soil’s brittle behaviour to a more ductile one. A reduction of up to 31% in the compressive strength happened in the 20% crumb content group. The compressive strength increases with the increase in the cement content. And the enlargement of cement content is more efficient at low cement content.

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Authors and Affiliations

F.C. Wang
W. Song
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Abstract

The general standards and guidelines recommendations for PCC suggest alternating conditions of curing: starting with wet conditions for effective hydration of Portland cement followed by air-dry conditions for polymer hardening. The often accepted curing regime of PCC covers 5 days of wet curing and then the air-dry curing but it is not the optimum one. The aim of the investigation was to find the best scenario for PCC with two types of polymer modifiers: two-component epoxy resin and water dispersion of polyacrylates. The following exploitation properties were accepted as the criteria of evaluation of PCC curing effectiveness: compressive strength, tensile splitting strength, surface tensile strength (by pull-off method), wear resistance, water penetration under pressure and resistance to carbonation. The optimum time of PCC wet curing is possibly between 7 and 14 days, however, it have to be verified experimentally for specific PCC composition.

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Authors and Affiliations

P. Woyciechowski
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Abstract

The study evaluated the curing properties of natural silica sand moulded with 1% by weight Furotec 132 resin binder catalysed by Furocure CH Fast acid and Furocure CH Slow acid. Physical properties of this sand included an AFS number of 47.35, 4.40 % clay, 0 % magnetic components, 0.13 % moisture, and 64.5 % of the size distribution spread over three consecutive sieves (150 – 600 μm). The sand was washed repeatedly to remove all the clay and oven dried. 2 kg washed sand samples were mulled with pre-determined weights of either catalyst to give 30 %, 50 % and 70 % by weight of 20 g Furotec 132 resin which was added last. Furotec 132 resin + Furocure CH Slow acid catalyst system gives longer bench lives and strip times but the maximum compressive strength in excess of 5000 N/cm2 is attained after more than 8.5 hours curing time irrespective of the weight % of catalyst added relative to the resin. On that basis, exceeding 30 weight % Furocure CH Slow acid catalyst when sand moulding with Furotec 132 resin has neither technical nor economic justification. In comparison, the Furotec 132 resin + Furocure CH Fast acid catalyst system was only capable of producing mould specimens with maximum compressive strength above 5000 N/cm2 at 30 weight % catalyst addition rate. At 50 and 70 weight % catalyst addition rates, the mulled sand rapidly turned dark green then bluish with a significant spike in temperature to about 40 oC, far exceeding the optimum curing temperature of Furotec 132. This high temperature accelerates the curing rate but with a very low degree of resin curing which explains the low compressive strength. In fact the sand grains fail to bond and have a dry, crumbly texture implying dehydration. Thus, not more than 30 weight % Furocure CH Fast acid catalyst should be used in sand moulding.

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Authors and Affiliations

M.M. Mashingaidze
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Abstract

This research was conducted to examine the corrosion behaviour of mild steel bar embedded in geopolymer paste based fly ash Class F during curing and non-curing process. The geopolymer paste was fabricated by blending in the fly ash with alkaline activators (NaOH solution with molarity of 12 M, 2.5 ratio of solution Na2SiO3/NaOH). The paste was produced in 50 mm × 50 mm × 50 mm mould where the mild steel bar of 100 mm (length) × 12 mm (diameter) was embedded at the center of geopolymer paste. This is to comprehend the corrosion behaviour of mild steel embedded in geopolymer paste with and without curing process. Process of curing is carried out for 24 hours at a temperature of 60°C in oven. While on the contrary, the non-curing process will only be leave at room temperature. Both samples were tested after 28 days of curing to determine the corrosion behaviour, phase analysis and morphology analysis. In accordance with the morphology analysis, it shows that the fly ash was totally reacted with alkaline solutions in curing geopolymer paste sample while the non-curing geopolymer paste has shown the unreacted fly ash with high number of pores. The phase analysis of mild steel embedded in this geopolymer paste during curing and without curing process has proven that the presence of new crystallographic peak which also known as passive layer occurred. The potential values result by OCP testing shows the curing sample has highest potential values as compared to the non-curing sample ones.
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Authors and Affiliations

Fatin Shahira Shaharudin
1
ORCID: ORCID
Farah Farhana Zainal
1
ORCID: ORCID
Nur Farhana Hayazi
1
ORCID: ORCID
Noraziana Parimin
1
ORCID: ORCID
Nur Izzati Muhammad Nadzri
1
ORCID: ORCID
Sri Hastuty
2
ORCID: ORCID
Andri Kusbiantoro
3
ORCID: ORCID

  1. Universiti Malaysia Perlis (UniMAP), Faculty of Chemical Engineering and Technology, Center of Excellence Geopolymer and Green Technology (CEGeoGTech), 01000 Perlis, Malaysia
  2. Universitas Pertamina, Department of Mechanical Engineering, Jakarta 12220, Indonesia
  3. Universiti Tun Hussein Onn Malaysia, Faculty of Engineering Technology, Johor, Malaysia
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Abstract

The essence of ablation casting technology consists in pouring castings in single-use moulds made from the mixture of sand and a watersoluble binder. After pouring the mould with liquid metal, while the casting is still solidifying, the mould destruction (washing out, erosion) takes place using a stream of cooling medium, which in this case is water. This paper focuses on the selection of moulding sands with hydrated sodium silicate for moulds used in the ablation casting. The research is based on the use of Cordis binder produced by the Hüttenes-Albertus Company. It is a new-generation inorganic binder based on hydrated sodium silicate. Its hardening takes place under the effect of high temperature. As part of the research, loose moulding mixtures based on the silica sand with different content of Cordis binder and special Anorgit additive were prepared. The reference material was sand mixture without the additive. The review of literature data and the results of own studies have shown that moulding sand with hydrated sodium silicate hardened by dehydration is characterized by sufficient strength properties to be used in the ablation casting process. Additionally, at the Foundry Research Institute in Krakow, preliminary semi-industrial tests were carried out on the use of Cordis sand technology in the manufacture of moulds for ablation casting. The possibility to use these sand mixtures has been confirmed in terms of both casting surface quality and sand reclamation.

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Authors and Affiliations

M. Hosadyna-Kondracka
K. Major-Gabryś
J. Kamińska
A. Grabarczyk
M. Angrecki
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Abstract

The objective of the presented paper is to investigate the performance of concrete containing volcanic scoria as cement replacement after 7, 28, 90, and 180 days curing. Five performance indicators have been studied. Compressive strength, water permeability, porosity, chloride penetrability, and reinforcement corrosion resistance have all been evaluated. Concrete specimens were produced with replacement levels ranging from 10 to 35%. Test results revealed that curing time had a large influence on all the examined performance indicators of scoria-based concrete. Water permeability, porosity, and chloride penetrability of scoria-based concrete mixes were much lower than that of plain concrete. Concretes produced with scoria-based binders also decelerated rebar corrosion, particularly after longer curing times. Furthermore, an estimation equation has been developed by the authors to predict the studied performance indicators, focusing on the curing time and the replacement level of volcanic scoria. SEM/EDX analysis has been reported as well.

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Authors and Affiliations

A. M. al-Swaidani
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Abstract

The present study examines some durability aspects of ambient cured bottom ash geopolymer concrete (BA GPC) due to accelerated corrosion, sorptivity, and water absorption. The bottom ash geopolymer concrete was prepared with sodium based alkaline activators under ambient curing temperatures. The sodium hydroxide used concentration was 8M. The performance of BA GPC was compared with conventional concrete. The test results indicate that BA GPC developes a strong passive layer against chloride ion diffusion and provides better protection against corrosion. Both the initial and final rates of water absorption of BA GPC were about two times less than those of conventional concrete. The BA GPC significantly enhanced performance over equivalent grade conventional concrete (CC).

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Authors and Affiliations

R. Saravanakumar
V. Revathi
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Abstract

Nowadays, geotechnical specialists are focused on reinforcing soil engineering parameters using innovative and environmentally friendly methods. Microbial-Induced Calcite Precipitation is a ground improvement method for modifying soil strength, permeability, and stiffness; therefore, it can be vital to study the effective factors on the technique’s efficiency and cost reduction. This study examined how biologically treated sands subjected to undrained triaxial loading responded to simultaneous changes in cementation solution molarity, optical density (OD600), and curing time. The triaxial experiments showed that the strength increased with the rise in the mentioned parameters. While the solution molarity and optical density had the highest and lowest effect on the soil improvement process, respectively, the optical density role was considerably low when the molarity was high. Increasing the molarity of the cementation solution resulted in a 45% increase in the peak stress ratio, while the optical density and curing time were constant. On the other hand, similar behaviour of dense sand and change in the response of cemented soil from strain-hardening to strain-softening were other notable observations of this study. In addition, the peak stress ratio at low strains increased with increasing the cementation level and then decreased to close to the amount of untreated sand with increasing strain.
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Authors and Affiliations

Seyed Abdollah Ekramirad
1
ORCID: ORCID
Mohammad Azadi
1
ORCID: ORCID
Nasser Shamskia
1
ORCID: ORCID

  1. Department of Civil Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran
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Abstract

Each year, mine and mill operations generate enormousamounts of two waste types – fine-grained tailings andcoarse-grained waste rocks. Fine-grained tailings are either discharged in slurry form to surface tailings dams ordelivered in cementitious form to underground mine stopes as backfilling, while coarse-grained rocks are typicallystored by depositing as a dry material in large dumps. The engineering design of surface tailings dams orunderground mine stopes is often controlled by the high compressibility and low shear strength characteristics offine-grained tailings. Cemented paste backfill CPB indicating saturated, fine-grained backfills can undergo majorconsolidation settlement during early curing stages. Thus, a better understanding of the rate and magnitude of bothdifferential and total settlement of CPB cured under stressis essential for a proper backfill geotechnical design. Theconsolidation parameters of CPB can be determined from an improved lab setup called CUAPS (curing underapplied pressure system). This setup is capable of simulating the CPB placement and curing conditions, andmeasuring the consolidation parameters of CPB cured under effective stresses ranging between 0.5 and 400 kPa.In this study, a series of one-dimensional consolidation tests were conducted on CPB samples allowing forexamination of the effects of binder type and rate as well as curing time on the compression properties (e.g.,coefficient of consolidationcv, compression indexCc, and recompression indexCr) and the final geotechnicalindex properties (e.g., void ratioef, water contentwf, and degree of saturationSf). Results showed that as the bindercontent increases, the initial resistance to consolidation increases. Thecvvalue decreases over the course of timedue to evolution of the CPB microstructure generated by the hydration process.

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Authors and Affiliations

Erol Yilmaz
Tikou Belem
Mostafa Benzaazoua
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Abstract

Zola's novel world can be seen as a play of forces that takes place in a strictly defined spatial configuration between aspirational characters striving to realize their desires; the body in motion becomes their expressive medium. Always semantically marked, movement is not only understood as the hero's movement between points in space. In this analytical perspective, based on the body of La Curée et L`Argent, the movement becomes the embodiment of the will / desire, the transformation of thought into action, what is potential into real.

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Authors and Affiliations

Jolanta Rachwalska von Rejchwald
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Abstract

The article has presented the method of 3D Digital Light Processing printing as one of the technologies used for rapid prototyping of dental models and making elements of dentures. In this work the research was presented, which the aim was to determine the effect of additional exposure time on the properties of the obtained printouts. Dynamic Mechanical Analysis test showed significant differences in stiffness between uncured specimens as well as specimens cured for 10, 20 and 30 minutes. In turn the obtained TG and DTG curves allowed to determine the most optimal curing time for DLP printouts. These studies provide the basis for determining the most appropriate method for handling printouts after the process of printing from liquid resin, so that they are the best possible quality for dentists and prosthodontists.
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Authors and Affiliations

J. Redutko
1
ORCID: ORCID
A. Kalwik
1
ORCID: ORCID
A. Szarek
1
ORCID: ORCID

  1. Czestochowa University of Technology, Faculty of Mechanical Engineering and Computer Science, Department of Technology and Automation,21 Armii Krajowej Av., 42-201 Czestochowa, Poland
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Abstract

The targeted modification of the material composition is a common procedure used to improve the parameters of the final products. This paper deals with the targeted modification of polymer systems composition using two various types of alternative fillers. The first type of alternative filler (SVD) has been obtained from energetics where it arises as a by-product of flue gas desulfurization. The second alternative filler used (KAL) is based on waste from glass production. The elastomeric systems designed for the production of car tires and solid wheels for transport systems were used in the role of modified polymer systems. Alternative fillers (SVD, KAL) have been applied as a substitution of commonly used fillers (carbon black, silica). The filler – elastomeric matrix interaction, rheology, cure characteristics, as well as hardness and rebound resilience of vulcanizates, which are important parameters for their industrial application, have been studied in the new prepared polymeric systems. The main output of the work is a new formulation of an elastomeric system for industrial applications with high rebound resilience and low rolling resistance, which is the subject of the international patent [1]. The modification of composition using raw material substitution can also bring significant environmental and economic effects.
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Bibliography

  1.  D. Ondrušová, M. Pajtášová, and I. Labaj, “Elastomer mixture and method of its preparation”, Patent PCT/SK2019/050015(2020). Available on: https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2020130952&_cid=P21-KBV9GG-52072-1
  2.  L.M. McKeen, “Thermoplastic Polyurethane Elastomers (TPU)”, in Permeability Properties of Plastics and Elastomers chapter 12.1 pp. 251‒285, (3rd Edition). USA, Elsevier, 2012.
  3.  I. Kücükrendeci, “The investigation of suitable welding parameters in polypropylene sheets joined with friction stir welding”, Bull. Pol. Acad. Sci. Tech. Sci. 67(1), 133‒140 (2019), doi: 10.24425/bpas.2019.127342.
  4.  D. Ondrušová, I. Labaj, M. Pajtášová, and J. Vršková, “Preparation and properties of new elastomeric systems containing alternative fillers”, MATEC Web of Conferences 254(8), 07003 (2019), doi: 10.1051/matecconf/201925407003.
  5.  D. Ondrušová, I. Labaj, J. Vršková, M. Pajtášová, and V. Mezencevová, “Application of alternative additives in the polymer composite systems used in automotive industry”, IOP Conf. Ser.: Mater. Sci. Eng. 776, 012101 (2020).
  6.  J. Vršková, D. Ondrušová, I. Labaj, and I. Kopal, “Effect of alternative filler from glass industry on the selected properties of friction polymermatrix in automotive industry”, IOP Conf. Ser.: Mater. Sci. Eng. 776, 012106 (2020).
  7.  M. Pajtášová, D. Ondrušová, R. Janík, Z. Mičicová, B. Pecušová, I. Labaj, M. Kohutiar, and K. Moricová, “Using of alternative fillers based on the waste and its effect on the rubber properties”, MATEC Web of Conferences 254(8), 04010 (2019).
  8.  I. Labaj, D. Ondrušová, J, Vršková, and M. Kohutiar, “The effect of various alternative filler granularity on the properties of elastomeric vulcanizate”, IOP Conf. Ser.: Mater. Sci. Eng. 776, 012098 (2020).
  9.  W. Dierkes, “Raw materials and compounds”, Twente: University of Twente, (2007). [Online]. http://laroverket.com/wpcontent/ uploads/2015/03/Raw_materials_and_compounds.pdf
  10.  Z. Zhenglong, S. Bin, L. Jiangang, D. Zhiguang, and H. Zhongbo, “Research on ride comfort performance of a metal tire”, Bull. Pol. Acad. Sci. Tech. Sci. 68(3), 491‒502 (2020), doi: 10.24425/bpasts.2020.133384.
  11.  P.E.P. Giannelis, “Polymer-layered silicate nanocomposites: synthesis, properties and applications”, Appl. Organomet. Chem. 12, 675–680 (1998).
  12.  A. Limper, Mixing of Rubber Compounds, p.192, Munich: Hanser Publishers, 2012.
  13.  J.S. Dick, “Technology – Compounding and Testing for Performance”, in Rubber Mixing, 2nd Edition, chapter XXIII, pp. 504‒522, Munich: Hanser Publishers, 2009.
  14.  J. D. Vicente, Rheology, p. 338, Rijeka: InTech, 2012.
  15.  ASTM D2084–01, 2001, Standard Test Method for Rubber Property—Vulcanization Using Oscillating Disk Cure Meter ,USA: Plan Tech Inc.
  16.  ASTM D2240–15, 2017, Standard Test Method for Rubber Property—Durometer Hardness, USA: Plan Tech Inc.
  17.  B. Banerjee, “Rubbers, Compounding Ingredients and their Criterion in Tyre Retreading” in Tyre Retreading, chapter I, pp. 1–29, Shawbury: Smithers Rapra Technology Ltd., 2015.
  18.  J.S. Dick, “ODR Cure Test Parameters”, in Basic Rubber Testing – Selecting Methods for A Rubber Test Program, USA: ASTM International, 2003
  19.  J.S. Dick, Rubber Technology – Compounding and Testing for Performance, p. 592, 2nd Edition, Hanser Publishers, Munich, 2009.
  20.  S.R. Khimi and K.L. Pickerink, “A New Method to Predict Optimum Cure Time of Rubber Compound Using Dynamic Mechanical Analysis”, J. Appl. Polym. Sci. 131, 1‒6 2014, doi: 10.1002/app.40008.
  21.  S. Futamura, “Elastomer compositions for tire treads having low rolling resistance and good wet and dry grip traction”, European Patent Specification EP0234303B1, 1986. [Online]. https://patents.google.com/patent/EP0234303B1/en
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Authors and Affiliations

Darina Ondrušová
1
Ivan Labaj
1
Mariana Pajtášová
1
Juliana Vršková
1
Slavomíra Božeková
1
Andrea Feriancová
1
Petra Skalková
1

  1. Alexander Dubček University of Trenčín, Faculty of Industrial Technologies in Púchov, Ivana Krasku 491/30, 020 01 Púchov, Slovakia
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Abstract

The objective of this study is to analyze effect of ground granulated blast furnace slag (GGBFS) in concrete on the pore structure, this research will contribute to the knowledge regarding the use of GGBFS as a cementitious material in terms of the future reference and potential improvement to the properties of concrete. To this aim, on the one hand a control specimens (CS) and another samples with 40% and 60% of GGBFS as replacement cement with moist cured at 20oC, 27oC, and cured at site. The compressive strength and the Mercury intrusion porosimetry (MIP) test were done. The result indicates that the strength of concrete with GGBFS at early ages tend to be lower in comparison with the CS. However, the GGBFS reaction plays important roles at the later ages. The samples cured at higher temperature produce higher strength value. The total pore volume (TPV) of the concrete use GGBFS decreases with increasing age.
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Authors and Affiliations

Abdul Chalid
1

  1. Senior Lectures Post Graduate of Civil Eng. Sangga Buana University, Jalan Surapati No. 189 Bandung-West Java 40123, Indonesia
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Abstract

The paper deals with the possibilities of using alkali silicate based inorganic binders for automotive industry aluminium castings production. In recent years, inorganic binders are coming back to the foreground and their manufacturers are developing new processes, which are starting to progressively supersede organic binder systems. Paper describes known knowledge about classic alkali silicate binders with focus on hardening processes and on improving their technological properties. Trends from the area of development and the use new alkali silicate based inorganic binders are also shortly described. As part of the experimental work, specific methods of producing samples were developed, with the help of which properties such as disintegration were subsequently evaluated by measuring abrasion and residual strengths. Characteristics such as residual compressive strength or shear strength at different thermal loads were also evaluated. When comparing the laboratory results with the results of de-coring in real conditions, a high degree of correlation was achieved, which makes it possible to determine the optimal recipe/procedure for the production of geometrically complex cores.
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Bibliography

[1] Jelínek, P. (1996). Foundry molding mixtures Part II, Binder systems of molding mixtures. Ostrava.
[2] Lewandowski, J.L. (1997) Plastics for casting molds. Kraków: WYD AKAPIT.
[3] Bolibruchova, D., Kuris, M., Matejka, M. & Kasinska, J. (2022). Study of the influence of zirconium, titanium and strontium on the properties and microstructure of AlSi7Mg0.3Cu0.5 alloy. Materials. 15(10). 3709, 1-20. DOI: 10.3390/ma15103709.
[4] Köhler, E., Klimesch, C., Bechtle, S. & Stanchev, S. (2010). Cylinder head production with gravity die casting. MTZ Worldwide. 71, 38-41. DOI: 10.1007/BF03227043. https://doi.org/10.1007/BF03227043.
[5] Polzin, H. (2014.) Inorganic Binders for mould and core production in the foundry. (1st. ed.) Berlin: Schiele und Schön.
[6] Antoš, P., Burian, A. (2002). Water glass - production, structure, properties and uses. Silchem
[7] Izdebska-Szanda, I., Palma, A., Angrecki, M. & Żmudzińska, M. (2013). Environmentally friendly mould technology. Archives of Foundry Engineering. 13(3), 37-42. DOI: 10.2478/afe-2013-0055.
[8] Stechman, M., Różycka, D. & Baliński, A. (2003). Modification of aqueous sodium silicate solutions with morphoactive agents. Polish Journal of Chemical Technology. 5(3), 47-50. ISSN (1509-8117).
[9] Jelínek, P. & Škuta, R. (2003). Modified sodium silicates – a new alternative for inorganic foundry binders. Materials Enginering. 10(3), 283.
[10] Mashifana, T. & Sithole, T. (2020). Recovery of silicon dioxide from waste foundry sand and alkaline activation of desilicated foundry sand. Journal of Sustainable Metallurgy. 6, 700-714. DOI: 10.1007/s40831-020-00303-5.
[11] Vasková, I. & Bobok, L. (2002). Some knowledge of the water glass modification by the phosphate compounds. Acta Metallurgica Slovaca. 8(2), 161-167.
[12] Major-Gabryś, K., Dobosz, St.M., Jelínek, P., Jakubski, J. & Beňo, J. (2014). The measurement of high-temperature expansion as the standard of estimation the knock-out properties of moulding sands with hydrated sodium silicate. Archives of Metallurgy and Materials. 59(2), 739-742. DOI: 10.2478/amm-2014-0123.
[13] Obzina, T., Merta, V., Folta, M., Bradáč, J., Beňo, J. Novohradská, N., et al. (2021). Technological and quality aspects of the use of innovative inorganic binders in the production of castings. Metals. 11(11), 1779, 1-13. DOI: 10.3390/met11111779.
[14] Izdebska-Szanda, I., Baliński, A., Angrecki, M. & Palma, A. (2014). The effect of nanostructure modification of the silicate binder on its binding characteristics and functional properties. Archives of Metallurgy and Materials. 59(3), 1033-1036. DOI: 10.2478/amm-2014-0173.
[15] Major-Gabryś, K., Dobosz, St.M., Jakubski, J. (2010). Self-hardened moulding sand with hydrated sodium silicate and liquid ester hardeners. In K. Świątkowski (Eds.), Polish Metallurgy in 2006-2010. (328-335). Krakow: Committee of Metallurgy of the Polish Academy of Science.
[16] Izdebska-Szanda, I. & Baliński, A. (2011). New generation of ecological silicate binders. Procedia Engineering. 10, 887-893. DOI: 10.1016/j.proeng.2011.04.146.
[17] Baliński, A. (2009). About structure of hydrated sodium silicate as a binder of moulding sands. Krakow: Foundry Research Institute.
[18] Izdebska-Szanda, I. (2012). Moulding sand with silicate binder characterized by beneficial technological and ecological properties. M.Sc. dissertation, Foundry Research Institute, Poland.
[19] Izdebska-Szanda, I., Stefański, Z., Pezraski, F. & Szolc, M. (2009). Effect of additives promoting the formation of lustrous carbon on the knocking out properties of foundry sands with new inorganic binders. Archives of Foundry Engineering. 9(1), 17 – 20.
[20] Izdebska-Szanda, I., Szanda, M. & Matuszewski, S. (2011). Technological and ecological studies of moulding sands with new inorganic binders for casting of non-ferrous metal alloys. Archives of Foundry Engineering. 11(1), 43-48. ISSN (1897-3310).
[21] Zaretskiy, L. (2016). Modified silicate binders new developments and applications. International Journal of Metalcasting. 10(1), 88-99. DOI: 10.1007/s40962-015-0005-3.
[22] Josan, A., Pinca‐Bretotean, C. & Ratiuc, S. (2021). Management of the regeneration process of the moulding mixtures in order to reduce the costs of the foundry type industrial enterprises. Materials Today: Proceedings. 45, 4161-4165. DOI: 10.1016/j.matpr.2020.12.034
[23] Davis, J.R. (1998). Metals Handbook. Desk Edition (2nd ed.) Boca Raton:CRC Press.
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Authors and Affiliations

M. Bruna
1
ORCID: ORCID
I. Vasková
2
ORCID: ORCID
M. Medňanský
1
ORCID: ORCID
P. Delimanová
2
ORCID: ORCID

  1. Faculty of Mechanical Engineering, Department of Technological Engineering, University of Zilina, Univerzitná 8215/1, 010 26 Žilina, Slovakia
  2. Institute Of Metallurgy, Faculty of Materials, Metallurgy and Recycling, Technical University of Košice, Letná 9, 042 00 Košice, Slovakia
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Abstract

The paper deals with the properties and microstructure of Reactive Powder Concrete (RPC), which was developed at Cracow University of Technology. The influence of three different curing conditions: water (W), steam (S) and autoclave (A) and also steel fibres content on selected properties of RPC was analyzed. The composite characterized by w/s ratio equal to 0.20 and silica fume to cement ratio 20%, depending on curing conditions and fibres content, obtained compressive strength was in the range from 200 to 315 MPa, while modulus of elasticity determined during compression was about 50 GPa. During three-point bending test load-deflection curves were registered. Base on aforementioned measurements following parameters were calculated: flexural strength, stress at limit of proportionality (LOP), stress at modulus of rapture (MOR), work of fracture (WF), and toughness indices I₅, I₁₀ and I₂₀. Both amount of steel fibres and curing conditions influence the deflection of RPC during bending.

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Authors and Affiliations

T. Zdeb
J. Śliwiński
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Abstract

This paper details the properties, microstructures, and morphologies of the fly ash-based alkali-activated material (AAM), also known as geopolymers, under various steam curing temperatures. The steam curing temperature result in subsequent high strengths relative to average curing temperatures. However, detailed studies involving the use of steam curing for AAM remain scarce. The AAM paste was prepared by mixing fly ash with an alkali activator consisting of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH). The sample was steam cured at 50°C, 60°C, 70°C, and 80°C, and the fresh paste was tested for its setting time. The sample also prepared for compressive strength, density, and water absorption testings. It was observed that the fastest time for the fly ash geopolymer to start hardening was at 80°C at only 10 minutes due to the elevated temperature quickening the hydration of the paste. The compressive strength of the AAM increased with increasing curing time from 3 days to 28 days. The AAM’s highest compressive strength was 61 MPa when the sample was steam cured at 50°C for 28 days. The density of AAM was determined to be ~2122 2187 kg/m3, while its water absorption was ~6.72-8.82%. The phase analyses showed the presence of quartz, srebrodolskite, fayalite, and hematite, which indirectly confirms Fe and Ca’s role in the hydration of AAM. The morphology of AAM steam-cured at 50°C showed small amounts of unreacted fly ash and a denser matrix, which resulted in high compressive strength.
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Authors and Affiliations

Rafiza Abd Razak
1 2
ORCID: ORCID
Sh. Nur Syamimi Sy. Izman
2
ORCID: ORCID
Mohd Mustafa Al Bakri Abdullah
1
ORCID: ORCID
Zarina Yahya
1 2
ORCID: ORCID
Alida Abdullah
1
ORCID: ORCID
Rosnita Mohamed
1
ORCID: ORCID

  1. Universiti Malaysia Perlis, Geopolymer and Green Technology, Center of Excellence (CEGeoGTech), Kangar, Malaysia
  2. Universiti Malaysia Perlis (UniMAP), Faculty of Civil Engineering Technology, Perlis, Malaysia
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Abstract

An attempt was made in the present work to study the compressive strength and microstructure of geopolymer containing high calcium fly ash (HCFA) and silica fume. Concentration of sodium hydroxide solution 8M, 10M, 12M & 14M, liquid to binder ratio 0.5 and sodium hydroxide to sodium silicate ratio 2.5 were selected for the mixes. Geopolymer mortar test results indicated that the mix with 40% silica fume by the weight of HCFA yielded higher compressive strength under ambient curing. The XRD pattern typically shows the major portion of amorphous phase of geopolymer. The existence of C-A-S-H gel, N-A-S-H gel and hydroxysodalite gel products were observed through SEM which developed dense microstructure and thus enhanced strength of HCFA and silica fume geopolymer.

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Authors and Affiliations

V.C. Prabha
V. Revathi
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Abstract

Microwave curing of bamboo fiber increases the physical and mechanical qualities of cement concrete, according to previous studies. However, there are limited research on their endurance when used as an additive in concrete manufacturing to increase strength. The impact of bamboo fiber and Styrene Butadiene Rubber (SBR) on the mechanical and microstructure of the resulting concrete is investigated in this study. With the inclusion of bamboo fiber ranging from 0–1.5%, a mix ratio of 1:1.5:3 was used. To make the samples, 10% SBR by weight of cement was dissolved in the mixing water. The batching was done by weight, with a water cement ratio of 0.6. Compressive strength, water absorption, swelling, modulus of elasticity, and modulus of rupture were all studied as mechanical properties. Various characterization tests such as SEM, EDS, FTIR, XRD, and TGA were performed on the microstructure, crystalline nature, and mineral composition of certain samples. According to the FTIR study’s findings, peak levels were detected in the O–H stretching, C–H fiber and CH2 functional groups, carbonyl group, C–O and C–C functional groups. As the temperature climbed, TGA measurements showed a drop in weight. The XRD test revealed peak levels of 6.611, 4.255, and 3.855 for sanidine, quartz, and calcite, respectively. After 28 days, the inclusion of bamboo fibers as an additive in concrete shows some promising outcomes in compressive strength, with samples containing 1% and 1.5% bamboo fiber cured at 80°C having a higher compressive strength value.
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Authors and Affiliations

Ajayi Joseph Adeniyi
1
ORCID: ORCID
James Gana
1
ORCID: ORCID
Ariyo Adanikin
ORCID: ORCID
Kola Ogedengbe
1
ORCID: ORCID
Abundance Idowu
1
ORCID: ORCID

  1. Landmark University, School of Engineering, Department of Civil Engineering, Omu-Aran, Kwara State, Nigeria
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Abstract

Due to the large amount of binder and low water-cement ratio, high-performance cement composites have high compressive strength and a dense hardened cement paste microstructure. External curing is insufficient, as it cannot reach the interior parts of the structure, which allows autogenous shrinkage to occur in the inside. Lack of prevention of autogenous shrinkage and high restraint causes structural microcracks around rigid components (aggregate, rebars). Consequently, this phenomenon leads to the propagation of internal microcracks to the surface and reduced concrete durability. One way to minimize autogenous shrinkage is internal curing. The use of soaked lightweight aggregate to minimize the risk of cracking is not always sufficient. Sorption and desorption kinetics of fine and coarse fly ash aggregate were tested and evaluated. The correlation between the development of linear autogenous shrinkage and the tensile stresses in the restrained ring test is assessed in this paper. A series of linear specimens, with cross-section and length custom designed to match the geometry of the concrete ring, were tested and analyzed. Determination of the maximum tensile stresses caused by the restrained autogenous shrinkage in the restrained ring test, together with the approximation of the tensile strength development of the cement composites were used to evaluate the cracking risk development versus time. The high-performance concretes and mortars produced with mineral aggregates and lightweight aggregates soaked with water were tested. The use of soaked granulated fly ash coarse lightweight aggregate in cementitious composites minimized both the autogenous shrinkage and cracking risk.
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Authors and Affiliations

Adam Zieliński
1
ORCID: ORCID
Anton K. Schindler
2
ORCID: ORCID
Maria Kaszyńska
1
ORCID: ORCID

  1. West Pomeranian University of Technology, Faculty of Civil Engineering and Environmental, al. Piastów 50a, 70-311 Szczecin, Poland
  2. Department of Civil and Environmental Engineering, Auburn University, 237 Harbert Center, Alabama 36849, Auburn, USA
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Abstract

This paper presents a detailed analysis of the work of Theodoret of Cyrus, the theologian and representative of the fifth-century Antiochian exegetical school, entitled Cure of the Greek Maladies, with reference to the passages presenting the question of pagan worship and, more specifically, his [Theodoret’s] position towards it. The Antiochenian understands perfectly well that literature, culture and philosophy are the meeting point between Christianity and Hellenism. He does not explicitly reject the entire output of Greek culture, because he believes that an attempt to reconcile Christianity with Hellenism is possible, but without the participation of pagan worship. Christianity’s superiority to Hellenism must undoubtedly be granted. The author of the apologia offers the pagans a remedy to cure themselves of the disease of conceit. Theodoret of Cyrus condemned, among other things, secret practices and bowing to statues (III, 84; III 85), rejected bloody and impious sacrifices (VII, 3; VII, 10; VII 22; VII, 24), warned not to confuse the cult of martyrs with supplication offerings to the dead for the well-being of the living (VIII, 33; VIII 34), and was critical of the Greek oracles (X, 2-3; X, 9). In order to show more fully the issue referred to in the theme, the historical and social context of the apologia are analysed and the circumstances of the formation of the author’s own reason and spirituality are also discussed.
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Authors and Affiliations

Maria Piechocka-Kłos
1
ORCID: ORCID

  1. Uniwersytet Warmińsko-Mazurski w Olsztynie

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