Wyniki wyszukiwania - Biblioteka Nauki

1

Method for assessment of changes in the width of cracks in cement composites with use of computer image processing and analysis

100%

Tomczak K. , Jakubowski J. , Fiołek P.

Studia Geotechnica et Mechanica

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2017

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tom Vol. 39, nr 2

73--80

EN

Crack width measurement is an important element of research on the progress of self-healing cement composites. Due to the nature of this research, the method of measuring the width of cracks and their changes over time must meet specific requirements. The article presents a novel method of measuring crack width based on images from a scanner with an optical resolution of 6400 dpi, subject to initial image processing in the ImageJ development environment and further processing and analysis of results. After registering a series of images of the cracks at different times using SIFT conversion (Scale-Invariant Feature Transform), a dense network of line segments is created in all images, intersecting the cracks perpendicular to the local axes. Along these line segments, brightness profiles are extracted, which are the basis for determination of crack width. The distribution and rotation of the line of intersection in a regular layout, automation of transformations, management of images and profiles of brightness, and data analysis to determine the width of cracks and their changes over time are made automatically by own code in the ImageJ and VBA environment. The article describes the method, tests on its properties, sources of measurement uncertainty. It also presents an example of application of the method in research on autogenous self-healing of concrete, specifically the ability to reduce a sample crack width and its full closure within 28 days of the self-healing process.

2

Stimulated autogenous-healing capacity of fiber-reinforced mortar incorporating healing agents for recovery against fracture and mechanical properties

88%

Buller A. S. , Abro F.-u. R. , Ali T. , Jakhrani S. H. , Buller A. H. , Ul-Abdin Z.

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tom Vol. 39, No. 1

33--48

EN

This study aimed to investigate the effect of autogenous healing capacity with the addition of expansive and crystalline agents on mechanical and fracture behaviors of fiber-reinforced (FR) mortar specimens with crack mouth opening displacement (CMOD) controlled test set-up. The experimental results of a self-healing approach of FR mortar were analyzed in terms of first cracking peak load (FCPL) increase, index of fracture toughness recovery (IFTR), and index of fracture energy recovery (IFER). Initially, the specimens were pre-cracked at different crack widths ranging from 30 μm to 200 μm after 28-days of curing. After pre-cracking, the specimens were kept in water for 56- and 120-day healing. A controlled three-point bending test (PBT) was applied on prism specimen having a central notch of 40 mm depth for pre-cracking as well as the post-conditioning stage for determining the FCPL. However, the crack surfaces were monitored by a high-range digital microscope and scanning electron microscope (SEM) to examine the nature of healed products near the damaged area. Test results revealed that a significant recovery of small cracks (≤50 μm) could be achieved for self-healing specimens by using healing agents (HA), while for large cracks (≥100 μm) partial recovery could be achieved after the 120-day healing period.

3

Influence of Aging Time at 850°C on Microstructure and Corrosion Resistance of a Cold Rolled 2205 Duplex Stainless Steel

88%

Assumpção R. F. , Fortes Monteiro J. C. , Campideli V. C. , Santos D. , Sicupira D. C.

Archives of Metallurgy and Materials

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2023

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tom Vol. 68, iss. 2

681--688

EN

The effect of aging time at 850°C for 300 s, 600 s, 1800 s, and 84600 s on the microstructural evolution and corrosion resistance of 2205 duplex stainless steel (DSS) was studied after cold rolling up to 60% of reduction. X-ray diffraction, scanning electron and transmission electron microscopy were used for microstructural characterization. The corrosion behavior was studied by cyclic potentiodynamic polarization (CPP) and electrochemical impedance technique (EIS) in 3.5% NaCl solution and the susceptibility to sensitization was investigated through the double loop electrochemical potentiodynamic reactivation (DL-EPR) test in 0.5 M H2SO4 + 0.1 M NaCl + 0.002 M KSCN solution. After cold working, increasing aging time led to an increase in sigma phase precipitation and a decrease in pitting corrosion resistance. However, the ultrafine microstructure had a beneficial influence on the self-healing effect in Cr and Mo depleted areas with the increasing of aging time, resulting in higher passivation ability. The DSS 2205 type was not susceptible to intergranular corrosion for the aged conditions applied.

4

Innovative modelling methods in damage assessment: application of dissipative particle dynamics to simulation of damage and self-healing of polymer-coated surfaces

75%

Jovanovic A. S. , Filipovic N.

Journal of Theoretical and Applied Mechanics

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2006

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tom Vol. 44 nr 3

637-648

EN

The paper presents an exemplary application of an innovative modeling technique (Dissipative Particle Dynamics - DPD) as a possible tool for multi-scale modeling of the behavior of advanced engineering materials (e.g. coated materials and/or multi-materials). The multi-scale modeling of the behavior of advanced engineering materials is primarily related to development of new techniques and methods needed to bridge the gap between the atomistic scale and macro applications. The presented example of examination of the applicability of the DPD to damage assessment dealing with the problem of interaction of particles, polymers and surfaces, is an issue concerning many applications in the colloid science. It has confirmed the applicability of the DPD as a method for linking the macro and atomistic scales. The imminent application of the method and the example are in the area of "self-healing" advanced engineering materials, thus in line with the objectives of EuMaT (cf. Appendix).

PL

W artykule zaprezentowano przykładową aplikację innowacyjnej techniki modelowania DPD (Dissipative Particle Dynamics - dynamika dyssypatywnego układu punktów materialnych) jako możliwego narzędzia do wielo-skalowego modelowaniazachowania się zaawansowanych materiałów inżynierskich (z pokryciami wierzchnimi, lub wieloskładnikowych). Modelowanie wielo-skalowe jest związane głównie z rozwojem nowych metod badawczych w opisie zjawisk przy przechodzeniu od poziomu atomistycznego do makroskali. Przedstawiona analiza przydatności metody DPD w szacowaniu zniszczenia zawierającego problem oddziaływania cząstek materiału, polimerów i powierzchni elementów stanowi przykład aplikacji nauki o koloidach. W pracy potwierdzono stosowalność DPD w efektywnym łączeniu makroskali z poziomem atomistycznym. Spodziewane zastosowania zaprezentowanej metody i omówiony przykład wchodzą w zakres zaawansowanych technologii samonaprawiających się materiałów, których rozwój jest konsekwencją wytycznych EuMat (w Dodatku).

5

Samonaprawiające się polimery. Cz. I. Stan obecny i perspektywy postępu

75%

Bandzierz K. , Bieliński D.

Elastomery

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2012

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tom T. 16, nr 4

15-21

PL

W artykule przedstawiono zagadnienie samonaprawy polimerów, ze szczególnym zwróceniem uwagi na grupę elastomerów. W tym kontekście samonaprawa definiowana jest jako zdolność materiałów do naprawy uszkodzeń mechanicznych, co prowadzi do odzyskania przez materiał właściwości takich samych lub zbliżonych do wyjściowych i tym samym do jego regeneracji. Podano ogólną charakterystykę polimerowych materiałów samonaprawiających się oraz omówiono główne mechanizmy samonaprawy. Ponadto zaprezentowano koncepcję badań własnych, zakładającą zaprojektowanie zdolnej do samonaprawy gumy technicznej z kauczuku butadienowo-akrylonitrylowego (NBR), której mechanizm regeneracji polegałby na możliwości dwuetapowego sieciowania - radiacyjnego oraz termicznego.

EN

Tis article provides an insight into subject-matter of self-healing polymers, with special focus on the group of elastomers. Herein, self-healing is defined as the ability of a materiał to repair mechanical damages, what gwes rise to regaining of its properties, the same or similar to primary materials, leading to their re.cove.ry. General characteristic of self-healing połymer materials and main self-healing mecha-nisms arę presented. Furthermore, concept of authors' own research, involving design of self-healing technical rubber based on butadiene-acrylonitrile rubber (NBR), which regeneration relies on possibility oftwo-stage crosslinking - radiation and thermal, is presented.

6

Application of Acoustic Emission Method to Determine Critical Stress in Fibre Reinforced Mortar Beams

75%

Ranachowski Z. , Jóźwiak–Niedźwiedzka, Daria , Brandt A. M. , Dębowski T.

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tom 37

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nr 3

7

Enhancing durability and sustainability in concrete with fibre-reinforced composites

75%

Salmi A.

Journal of Water and Land Development

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2024

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tom no. 61

48--54

EN

This paper presents a study focused on two pivotal innovations in the field of fibre-reinforced concrete (FRC) to significantly enhance its durability and sustainability in construction. First, our research investigates the application of advanced self-healing mechanisms in FRC. By embedding microcapsules containing healing agents within the concrete matrix, we achieved a remarkable reduction in crack propagation and improved structural integrity. Our results demonstrate that the self-healing FRC exhibited a 30% increase in compressive strength and a 40% reduction in crack width, leading to a longer service life for concrete structures. Second, we explore the integration of sustainable materials in FRC production. By incorporating locally sourced and recycled materials, we successfully reduced the environmental impact associated with FRC manufacturing. Our findings reveal a substantial reduction in carbon emissions, with a 25% decrease in the overall carbon footprint of FRC production. This innovation not only contributes to a greener construction industry but also aligns with sustainability goals and regulations. This research underscores the transformative potential of self-healing mechanisms and sustainable material integration in FRC, offering tangible results in terms of increased durability and reduced environmental impact. These innovations promise to reshape the construction landscape, aligning it with the principles of sustainability and long-term structural resilience.

8

Application of Acoustic Emission Method to Determine Critical Stress in Fibre Reinforced Mortar Beams

75%

Ranachowski Z. , Jóźwiak-Niedźwiedzka D. , Brandt A. M. , Dębowski T.

Archives of Acoustics

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2012

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tom Vol. 37, No. 3

261-268

EN

The objective of this investigation was to test the effectiveness of the Acoustic Emission (AE) mea- surements in determining the critical stresses during four-point bending of mortar beams. Within the measuring procedure the parameter σcr/σ300 was calculated and analysed. Additionally, the influence of cement replacement by high calcium fly ash (HCFA) on the process of crack healing was discussed. Mortar beams with different content of HCFA and reinforced by steel microfibres were prepared for tests. After curing in standard conditions the beams were subjected to four-point bending test in order to introduce the pre-cracking. Thereafter the beams were cured in the lime water and loaded after 56 and 112 days in the same way as for the first time. Additionally the microstructure of mortars was studied in a stereo optical microscope as well in an electron scanning microscope including the Energy Dispersive X-ray analysis (EDX). The results of microstructural characterization of mortar containing HCFA from lignite combustion are presented. The applied load level slightly exceeded the critical stress, producing intense crack growth processes however did not significant affected the load capacity of the beams. During the consecutive loading the decreasing tendency of σcr/σ300 ratio was noted. The obtained results confirm that the latter parameter can be applied as a measure of the composite degradation level for the elements carrying the repeated loads of amplitude close to the critical stress of the structure and also that the cement replacement with HCFA influences the process of crack healing.

9

Religious Healing and the Asclepius Cult: A Case of Placebo Effects

63%

Panagiotidou O.

Open Theology

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2016

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tom 2

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nr 1

EN

This paper suggests a cognitive approach to the Asclepius cult which may throw light on the supplicants’ personal experiences of healing during the ritual of incubation. In particular, the possibility of healing at the Asclepius sanctuaries is presented as a potential result of the patients’ placebo responses. The prerequisites of placebo effect as determined by Nicholas Humphrey are traced in the wider social and conceptual contexts of Greek antiquity and the specific religious context of the Asclepius cult. In this framework, it is argued that personal experiences of people, social information about the Asclepius’ healing powers and the confirmation of this information by human doctors would have influenced how people “lived” an illness or a disease infliction, “appropriated” the religious beliefs in Asclepius, and experienced cures at the asclepieia. These cures could have derived from patients’ self-healing mechanisms, but would have been perceived and conceptualized as “healing miracles” performed by the god. This preliminary study intends to show how cognitive approaches can enrich historical knowledge on the Asclepius cult and on supplicants’ healing experiences, suggesting that such approaches may contribute to a better understanding of “lived religion” and of multiple religious experiences in various religious contexts.

10

Współczesne koncepcje samozaleczania i samonaprawy betonu

63%

Łukowski P. , Garbacz A. , Adamczewski G.

Materiały Budowlane

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2016

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tom nr 11

36--37

PL

W artykule przedstawiono koncepcję samozaleczania i samonaprawy betonu. Omówiono mechanizmy oraz sposoby sterowania tymi zjawiskami, to znaczy sposoby nadawania betonowi zdolności do samonaprawy. Zwrócono uwagę na zastosowanie rozproszonych nośników substancji naprawczej, w tym zwłaszcza możliwość wykorzystania żywicy epoksydowej bez utwardzacza jako modyfikatora kompozytu cementowego. Wskazano dotychczasowe osiągnięcia oraz problemy do rozwiązania, wytyczające niezbędne kierunki dalszych badań w tym zakresie.

EN

The paper deals with the idea of self-healing and self-repair of cement concrete. The mechanisms of these phenomena have been described together with the methods of their controlling, i.e. granting to the concrete the ability to self-repair. The particular attention has been paid to the use of dispersed carriers of the repair mean, including the possibility of application of epoxy resin without a hardener as the modifier for the cement composite. The present achievements have been pointed out as well as the problems to resolve, showing the necessary directions of the further researches in this area.

11

Investigation on self‑healing of neat and polymer modified asphalt binders

63%

Wang C. , Xue L. , Xie W. , Cao W.

Archives of Civil and Mechanical Engineering

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2020

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tom Vol. 20, no. 2

27--36

EN

The paving asphalts have long been recognized to be capable of self-healing. The objective of this study was to evaluate the healing potential of asphalt binders and investigate its relationship with molecular characteristics in terms of composition and structures. Five neat and styrene–butadiene–styrene (SBS) modified asphalt binders were characterized using the recently developed linear amplitude sweep-based healing test. The data were analyzed based on the viscoelastic continuum damage theory to establish healing master curves and determine the healing rate HR. Chemical evaluation methods included saturates, aromatics, resins, and asphaltenes fractionation, gel permeation chromatography, and nuclear magnetic resonance spectroscopy. Results indicated that the presence of more light/low-polarity fractions of saturates and aromatics or higher concentrations of small molecules promoted healing, as these molecules were expected to have higher mobility facilitating molecular diffusion across crack interfaces. Lower percentages of aromatic ring structures and more aliphatic chains corresponded to higher healing rates. The SBS-modified asphalt binders contained higher concentrations of aromatic rings, but still provided comparable healing potential with the neat asphalts.

12

A Dynamic Self-healing Key Management Scheme For Wireless Sensor Networks Based on EBS

63%

Ning J. , Yin X.

Przegląd Elektrotechniczny

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2013

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tom R. 89, nr 3b

92--94

EN

A self-healing mechanism in key management is an important means for large-scale clustering wireless sensor networks that enable nonrevoked nodes use their private information and the received broadcast messages to recover the lost session keys on their own. In this paper, we propose a dynamic self-healing key management scheme for large-scale clustering wireless sensor networks that is based on Exclusion Basis System (EBS). We use forward and backward key chains to form cluster session key chain for self-healing, take t-degree polynomial keys to replace the original keys used in EBS. The analysis shows that the proposed scheme has the properties of forward and backward secrecy and resisting to a collusion attack, which is suitable for resource-constrained wireless sensor networks.

PL

W artykule zaproponowano schemat samo-naprawialnego dynamicznego zarządzania kluczami w sieci czujników bezprzewodowych o dużej skali klasterów, oparty na metodzie wykluczeń EBS. Dzięki wykorzystaniu łańcuchów klucza w przód i wstecznych uzyskano samonaprawialność, natomiast oryginalne klucze w EBS zastąpiono kluczami wielomianowymi stopnia t. Analiza działania wykazała skuteczność opisanego schematu w obronie przed atakami.

13

Biobeton – materiał budowlany przyszłości?

63%

Beściak G. , Śmiszek-Lindert W. , Lewicka S.

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tom R. 21/83, nr 2

137--143

PL

Beton należy do materiałów tanich, powszechnie dostępnych, a przy tym o dużej wytrzymałości i trwałości. Niestety, kompozyt ten jest również podatny na uszkodzenia, przede wszystkim pod wpływem wysychania i działania mrozu co może powodować powstawanie spękań, ułatwiających wnikanie korozyjnych roztworów soli wywołujących korozję chemiczną. Przez wiele lat stosowano różne metody naprawy uszkodzeń tego materiału, jednak dopiero wprowadzenie mikroorganizmów produkujących węglan wapnia, stwarza duże możliwości uzyskania postępu w procesach renowacji betonu. Biobeton zawierający przetrwalniki bakterii ma zdolność do samo-naprawy mikrospękań, co przedłuża trwałość materiału, a także zmniejsza jego podatność na odziaływanie niekorzystnych warunków w trakcie eksploatacji. W artykule dokonano przeglądu prac naukowych, omówiono dostępne technologie uzyskiwania biobetonu oraz najważniejsze problemy do rozwiązania.

EN

Concrete is one of the cheapest and most widely available materials, and at the same time with high strength and durability. Unfortunately, this composite is also susceptible to damage by drying and frost action, which may lead to cracking, facilitating the penetration of corrosive solutions. Over many years different methods were applied have to repair the damaged of this material, but only the use of microorganisms producing calcium carbonate have created the possibility to attain the progress in the renovation of concrete. The bioconcrete containing bacterial spores has the ability to self-healing of the microcracks, which prolongs the durability of the material and reduces its susceptibility to the destructive conditions during exploitation. The purpose of this paper is to review the scientific works and available technologies of bioconcrete production and the most important problems which need to be solved.

14

A study on microbial self-healing concrete using expanded perlite

63%

Amjad U. B. , Siddique M. S. , Shahid T. , Ahmed I. , Alogla S. M. , Ahmad J.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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tom Vol. 71, nr 5

art. no. e146475

EN

The increasing concern for the safety and sustainability of structures is calling for the development of smart self-healing materials and preventive repair methods. This research is carried out to investigate the extent of self-healing in normal-strength concrete by using Sporosarcina aquimarina – NCCP-2716 immobilized in expanded perlite (EP) as the carrier. The efficacy of crack-healing was also tested using two alternative self-healing techniques, i.e. expanded perlite (EP) concrete and direct introduction of bacteria in concrete. A bacterial solution was embedded in EP and calcium lactate pentahydrate was added as the nutrient. Experiments revealed that specimens containing EP-immobilized bacteria had the most effective crack-healing. After 28 days of healing, the values of completely healed crack widths were up to 0.78 mm, which is higher than the 0.5 mm value for specimens with the direct addition of bacteria. The specimen showed a significant self-healing phenomenon caused by substantial calcite precipitation by bacteria. The induced cracks were observed to be repaired autonomously by the calcite produced by the bacteria without any adverse effect on strength. The results of this research could provide a scientific foundation for the use of expanded perlite as a novel microbe carrier and Sporosarcina aquimarina as a potential microbe in bacteria-based self-healing concrete.

15

Autonomous self-healing coating of PMMA microcapsules filled with epoxy

63%

Mohammed A. F. , Hamza A. F. , Al-Kawaz A. E.

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tom Vol. 23, No. 1

no. art. 2022108

EN

Composites that owns healing property has acquired wide range of application especially in coatings. Microcapsules embedded coatings provide both damage protection and damage management imposing itself among the sophisticated applications. Although the microcapsules coatings have spectacular aspect, their effect on coating properties still under study due the broad properties variation of microcapsules. In this work, PMMA microcapsules filled with Bisphenol-A epoxy is incorporated into epoxy coating. The coating is self-healing and can be used for anti-corrosion applications. The properties of the prepared coating were investigated via scratch test and through microhardness test and the healing process is monitored through optical microscope. The investigation shows that embedding microcapsules into epoxy matrix will achieve both in self-healing coating and better performance.

16

Sposoby samozaleczania rys w tworzywach cementowych

63%

Dudek M. , Stryszewska T. , Kańka S.

Inżynieria i Budownictwo

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2021

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tom R. 77, nr 7

345--348

PL

Przedstawiono zagadnienie samoleczenia tworzyw cementowych. Jest to proces polegający na niwelowaniu uszkodzeń. W przypadku materiałów cementowych dotyczy zamykania powstałych rys. Wyróżnia się dwie grupy procesów prowadzących do wypełnienia zarysowań: procesy autogeniczne i autonomiczne. Opisano metody samoleczenia wraz z wynikami obserwacji mikrostruktury trzech wybranych metod.

EN

The article presents the issue of self-healing of cement materials. It is a process of repairing damage. In the case of cement materials, it concerns closing the cracks that have been formed. There are two groups of processes leading to the filling of cracks: autogenous and autonomous processes. The paper describes the methods of self-healing and the results of observation of the microstructure of three selected methods.

17

Fatigue tests, self-healing of polymer-matrix composites in unmanned aerial vehicles

63%

Augustyn S. , Kowalski R.

|

tom No. 48

83--106

EN

This publication presented the main issues related to fatigue of polymer composite materials. It was featured a fatigue stress test based on composite sample, made of carbon fiber-reinforced polymer, using the four-point bending method. The test was carried out with the initial load and using positive load cycles. The perspectives of diagnostics and self-healing of composite materials, including intelligent materials, were also presented.

PL

W publikacji przedstawiono kluczowe zagadnienia dotyczące zjawiska zmęczenia polimerowych materiałów kompozytowych. Omówiono próbę zmęczeniowego obciążenia próbki, wykonanej z materiału kompozytowego wzmacnianego tkaniną węglową o osnowie polimerowej, przy wykorzystaniu metody zginania czteropunktowego. Doświadczenie wykonane zostało przy wstępnym obciążeniu próbki oraz zastosowaniu cykli jednostronnych dodatnich. Przedstawiono również perspektywy rozwoju diagnostyki i samonaprawy zmęczeniowej materiałów kompozytowych, z uwzględnieniem materiałów inteligentnych

18

Waste frying oil modified bitumen usage for sustainable hot mix asphalt pavement

63%

Eriskin E. , Karahancer S. , Terzi S. , Saltan M.

|

2017

|

tom Vol. 17, no. 4

863--870

EN

Asphalt concrete is composed primarily of aggregate and asphalt binder. By volume, a typical Hot Mix Asphalt (HMA) mixture is about 85% aggregate, 10% asphalt binder, and 5% air voids. Bitumen is very important as a binder material in asphalt concrete. However, the cost of the bitumen is relatively high. For this reason, highway professionals are looking for modifiers to decrease the bitumen content used in the asphalt pavement. In this study, waste frying oil (WFO) is used as a modifier to modify the bitumen. As a result, by adding WFO into the bitumen, optimum binder content of a mixture was decreased from 5.125% down to 4.575%. So that, roads constructed with WFO modified bitumen are sustainable because of decreasing the bitumen rate used in the mixture. In addition, softening point of the modified bitumen is decreased (up to 82%) while the penetration value is increased (up to 240%) by modifying the bitumen with WFO. The tensile strength ratios of the modified asphalt specimens are all above the minimum specification limit, 80%. Finally, required temperature for fast self-healing is decreased by modifying the bitumen with WFO. Specimens prepared with WFO modified bitumen are healed compared to the reference specimen.

19

Samozaleczanie i samonaprawa betonu

51%

Łukowski P. , Adamczewski G.

Inżynieria i Budownictwo

|

2017

|

tom R. 73, nr 8

421--424

PL

Przedstawiono koncepcję samozaleczania i samonaprawy betonu. Omówiono mechanizmy oraz sposoby sterowania tymi zjawiskami. Zwrócono uwagę na zastosowanie rozproszonych nośników substancji naprawczej, w tym możliwość wykorzystania żywicy epoksydowej bez utwardzacza. Wskazano dotychczasowe osiągnięcia oraz problemy do rozwiązania, wytyczające niezbędne kierunki dalszych badań w tym zakresie.

EN

The paper deals with the idea of self-healing and self-repair of cement concrete. The mechanisms of these phenomena have been described together with the methods of their controlling. The particular attention has been paid to the use of dispersed carriers of the repair mean, including the possibility of application of epoxy resin without a hardener. The present achievements have been pointed out as well as the problems to resolve.

20

Zarastanie rys w zaprawach cementowych z popiołem wapiennym zbrojonych rozproszonymi włóknami

51%

Jóźwiak-Niedźwiedzka D. , Brandt A. M. , Ranachowski Z.

|

2012

|

tom R. 17/79, nr 1

38-49

PL

W przeprowadzonych badaniach wykonano próbki w kształcie beleczek z zaprawy uzbrojonej mikrowłóknami, przy różnym stopniu zastąpienia cementu przez popiół lotny wapienny. Przedstawiono wyniki mikroskopowej charakterystyki popiołu lotnego klasy C ze spalania węgla brunatnego. Analizę mikrostruktury zapraw przeprowadzono w mikroskopie optycznym oraz mikroskopie skaningowym. Badane beleczki były zginane aż do otwarcia rys i mikro rys, które podlegały zarastaniu po różnych okresach pielęgnacji. Uzyskane rezultaty wykazują, że zastąpienie cementu popiołem lotnym wapiennym wpływa na przebieg procesu samozarastania. Dodatek popiołu wapiennego, zarówno 30% jak i 60% przyspiesza proces samorzutnego zarastania rys, a zwłaszcza mikrorys. W badaniach nie stwierdzono przypadku całkowitego wypełnienia rys nowymi fazami, a jedynie udokumentowano początek takiego procesu. Stwierdzono także, że częściowe zastąpienie cementu przez popiół lotny wapienny zmniejsza stosunek S03/Al2O3 w zaprawie, stwarzając tym samym korzystne warunki do powstawania monosiarczanu.

EN

A series of mortar beams was cast with various content of high calcium fly ash as a partial replacement of Portland cement. The results of microstructural characterization of mortar containing fly ash class C (High Calcium Fly Ash) from combustion of lignite are presented. The evaluation ot the microstructure was performed using SEM and optical microscopy. The tested beams were bent till the crack and microcracks opening, which were healed during the different curing time. The results showed that the replacement of cement with fly ash class C influenced the process ot crack healing. The addition ot high calcium fly ash, at both 30% and 60%, speeds up the selt-healing process in cracks and particularly in micro-cracks. In the research the completely filling up of the eracks by new phases has not been observed, only the beginning of such process has been noticed. Additionally, it has been concluded that the partially replacement ot cement by high calcium fly ash decreased the ratio of SO3/Al2O3 in the mortar, owing to the fact that monosulfate could be created.