Poly - News
New publication
T. B. Mrohs, O. Weichold
Hydrolytic Stability of Crosslinked, Highly Alkaline Diallyldimethylammonium Hydroxide Hydrogels
Gels 2022, 8, 669. https://doi.org/10.3390/gels8100669
New publication
A. Jung, O. Weichold
A 3-in-1 alkaline gel for the crack injection in cement-based materials with simultaneous corrosion protection and re-passivation of crack-crossing steel rebars
Construction and Building Materials 2022, 344, 128092. https://doi.org/10.1016/j.conbuildmat.2022.128092
New publication
T. B. Mrohs, O. Weichold
Multivalent Allylammonium-Based Cross-Linkers for the Synthesis of Homogeneous, Highly Swelling Diallyldimethylammonium Chloride Hydrogels
Gels 2022, 8, 100 (open access)
New doctoral student
Since January, Nils Münstermann has been supporting the research group in the area of bio-based building materials and is developing swellable chitosan derivatives for concrete and agricultural applications.
Lecture announcement
O. Weichold
Alkaline hydrogels – multifunctional materials for concrete rehabilitation – International Congress on Polymers in Concrete (IPCIC 2022)
POSTPONED TO 2023
Lecture announcement
O. Weichold
High-alkaline hydrogels - the Swiss Army Knives of restoration
NuBau – 5. Tagung Nutzerorientierte Bausanierung, Weimar.
POSTPONED TO 2023
New publication
M. Brenner, O. Weichold
Poultry Feather Waste as Bio-Based Cross-Linking Additive for Ethylene Propylene Diene Rubber
Polymers 2021, 13(22), 3908 (open access)
Master thesis completed
Congratulations to Nils Münstermann on the successful completion of his master's thesis entitled "Synthesis and properties of superabsorbents based on chitosan hydrogels" in the Chemistry program!
The thesis originated in the ongoing project Biosuperabsorbers.
Front page
The publication Alkaline hydrogels as ion-conducting coupling material for electrochemical chloride extraction by Andre Jung in Mater. Corr. has made it to the cover of volume 72 issue 9!
Click here for the Cover→
New publication
P. B. Sassmann, O. Weichold
Synergistic effects in cross-linked blends of ion-conducting PEO-/PPO-based unsaturated polyesters
Ionics 2021, 27, 3857–3867 (open access)
New project: Bio-based glazes and adhesives for wood
A new project focusing on bio-based building materials will start on 1.10.2021. Based on chitosan, we are developing glazes and adhesives for wood together with two industrial partners. The project is supervised by Tobias Boehnke.
Lecture
Report from the ongoing project Rissinjektion:
O. Weichold
Acrylic-free two-component gels for crack injection
7. Kolloquium „Erhaltung von Bauwerken“, Technische Akademie Esslingen, 14.7.2021, Ostfildern
Lecture
Report from the completed project Chloride extraction with gel:
O. Weichold
Alkaline hydrogels as coupling material for electrochemical chloride extraction
7. Kolloquium „Erhaltung von Bauwerken“, Technische Akademie Esslingen, 14.7.2021, Ostfildern
New publication
A. Jung, A. Faulhaber, O. Weichold
Alkaline hydrogels as ion-conducting coupling material for electrochemical chloride extraction
Matter. Corr. 2021, 72, 1448–1455 (open access)
A publication from the completed ZIM project "Chloride extraction with gel".
Lecture
O. Weichold
Self-extinguishing wood-fibre boards using waste poultry-feather hydrolysates
1st International Conference on Science Technology & Innovation, 19.3.2021, Chiang Mai, Thailand
Lecture
Report from the completed project Chloride extraction with hydrogels:
O. Weichold
Electrochemical Chloride Extraction using diallyldimethylammonium hydroxide based hydrogels as electrolytes
3rd International Conference on the Chemistry of Construction Materials, 17.3.2021, Karlsruhe
Got up to speed
For the reproducible and high-quality production of test specimens and samples, e.g. from our biobased materials, we have procured a Stepcraft M-1000 CNC milling machine with a working range of 679 × 1044 mm2. Contact person is Tobias Boehnke.
Front page
The publication Protein Hydrolysates from Biogenic Waste as an Ecological Flame Retarder and Binder for Fiberboards von Markus Brenner hat es auf die Titelseite der Ausgabe 5 Band 50 geschafft! Hier geht es zum Cover→
New project: Biosuperabsorber
Retroactive to 1.1., we were approved for a project to develop water-swellable materials based on renewable raw materials. In cooperation with industrial partners, the relationship between composition and properties is being clarified, capacities for scale-up are being built up and suitable prototypes are being tested in end applications. The project is supervised by Tobias Boehnke.
New project: recycled foams
Retroactive to 1.11., we were granted a project for the development of mechanically stable foams. The project is based on the materials described in Appl. Sci. 2020. In addition, the effect of fillers made from recycled materials is being tested. The project is supervised by Fabian Weitenhagen.
New employee
Since December, Fabian Weitenhagen has been supporting the working group in the area of bio-based building materials and is developing the initial work on polycondensation resins (Appl. Sci. 2020) further.
New publication
M. Brenner, O. Weichold
Protein Hydrolysates from Biogenic Waste as an Ecological Flame Retarder and Binder for Fiberboards
ACS Omega 2020, 5, 32227 (open access).

Publication
A. Jung, M. B. Endres, O. Weichold
Polymers 2020
To the article→
Influence of Environmental Factors on the Swelling Capacities of Superabsorbent Polymers Used in Concrete
ABSTRACT: Superabsorbent polymers (SAP) are of major interest as materials to control the cement hydration process. The swelling behavior of the SAPs significantly influences the performance of the resulting concrete by slowly releasing polymer-bound water in order to maintain a consistent w/c value. A round-robin test conducted by the RILEM Technical Committee 260-RSC showed that the same batch of polymer can lead to large deviations in concrete performance and this was assumed to originate in di
erent storage conditions of the SAP. In this contribution the change in the performance of two SAPs, a crosslinked poly(acrylate) and a crosslinked poly(acrylate-co-acrylamide), was assessed after ageing in standard climate, at 50
°C, and under UV irradiation. During storage in standard climate or 50 °C, ageing led to dehydration of the SAP, and this subsequently led to a higher water uptake during swelling. By contrast, UV irradiation reduced the water uptake, most likely as a result of photo-crosslinking. Dynamic water vapor sorption experiments indicated a strong dependence of the water uptake on both the ambient humidity and the temperature. As a result, cement mixtures containing SAP must be calculated on the dry mass of the SAP rather than the actual weight on site. A standard procedure of how to pack and handle SAP to be used in concrete is also provided.
Bachelor thesis
Denis Clou
Congratulations on the successful completion of the bachelor thesis
Geflügelfedern als biobasierter Füllstoff in Elastomerlagern
Use of poultry feathers as a bio-based filler in elastomer bearings
Bachelor thesis
Marvin Oomen
Congratulations on the successful completion of the bachelor thesis
Chitosanbasierte Interpolyelektrolytkomplexe zur Oberflächenversiegelung
Chitosan-based interpolyelectrolyte complexes for surface sealing

Publication
M. Brenner, C. Popescu, O. Weichold
Appl. Sci. 2020
To the article→
Anti-Frothing Effect of Poultry Feathers in Bio-Based, Polycondensation-Type Thermoset Composites
ABSTRACT: The formation of polycondensation-type thermoset resins from natural reactants such as citric and glutaric acid, as well as 1,3-propanediol and glycerol, was studied. Monitoring the mass loss by thermogravimetric analysis (TGA) allowed the rate constants of the esterification to be calculated, which were in the order of 7·10−5 s−1 for glutaric acid and approximately twice as high for citric acid. However, the combination citric acid/glycerol was previously reported to froth up at high conversions, giving rise to foams, which makes the preparation of compact engineering composites challenging. In light of this, we observed that shredded poultry feathers not only increased the conversion and the reaction rate of the combination citric acid/glycerol, but increasing the amount of feathers continuously decreased the number of visible bubbles. The addition of 20 wt% of feathers completely prevented the previously reported frothing and gave rise to compact materials that were macroscopically free of defects. Besides this, the addition of feathers also improved the fire-retardant properties. The tensile properties of the first specimens are still rather low (σ = 11.6 N/mm2, E = 750 N/mm2), but the addition of poultry feathers opens a new path for green thermoset resins.
Master thesis
Tim Mrohs
Congratulations on the successful completion of the Master's thesis
Synthese von vernetzten Copolymerelektrolytgelen auf Basis von Diallyldimethylammoniumchlorid und -hydroxid
Synthesis of crosslinked copolymer electrolyte gels based on diallyldimethylammonium chloride and -hydroxide
Lecture
O. Weichold, P. B. Sassmann
Jahrestagung der GDCh-Fachgruppe Bauchemie, 1.10.2019, Aachen
Numerical structural analysis for the in silico design of advanced hybrid materials
ABSTRACT: Modern high-performance materials obtain their extraordinary properties from the interaction of individual components. From mechanical point of view, however, problems arise in determining the macroscopic macroscopic material behaviour. The aim is therefore to determine the material behaviour by numerical simulation using the example of a polymer-impregnated concrete body.
Lecture
M. Brenner
Jahrestagung der GDCh-Fachgruppe Bauchemie, 1.10.2019, Aachen
Use of feather keratin as fire protection impregnation for wood and as non-combustible thermal insulation material
ABSTRACT: New uses for feathers are shown, as they are produced in large quantities as a biogenic residual material. The improvement of the fire properties is a central point. On the one hand, the feathers are processed into a non-combustible thermal insulation board. In addition, solutions containing keratin are used to treat wood-based materials in order to specifically reduce their flammability and improve their smouldering behaviour.
Bachelor thesis
Kaja Kensmann
Congratulations on the successful completion of the bachelor thesis
Thermoplastische Verarbeitung von Federn mit einem polymerisierbaren Weichmachersystem
Thermoplastic treatment of feathers with a polymerizable plasticizer system
Bachelor thesis
Sarah Weides
Congratulations on the successful completion of the bachelor thesis
Synthese und elektrochemische Charakterisierung von Oligoethylenglykol-modifizierten 4,4′-Bipyridinen
Synthesis and electrochemical behaviour of oligoethyleneglycol-modified 4,4′ bipyridines
Lecture
O. Weichold
European Polymer Congress, 13. Juni 2019, Kreta
Fighting fire with feathers – transforming natural waste into flame-retardant materials
ABSTRACT: Keratin is a natural fibre protein widely found in the animal kingdom, where it is the basis of e. g. wool and hair, horns, scales, and feathers. Besides its broad spectrum of mechanical properties, keratin is particularly characterized by its poor flammability and even self-extinguishing behaviour. Most approaches which use keratin as a chemical feedstock require a solubilisation step, and this can be accomplished by either alkaline hydrolysis or reduction of the disulphide bridges. We have refined the latter to be more convenient and economical, but more importantly to produce two kreatin fractions, which were both found to be valuable intermediates in producing flame-retarding materials. The first fraction consists of water-soluble protein hydrolysates, which can be used as impregnation for particle and fibre boards. The second fraction is a gel, which can be transformed into foamed boards. These materials match commercial EPS/XPS boards in terms of their thermal conductivities, but will not ignite or burn when subjected to an open flame. The contribution will present our latest results on the preparation and application of these two fractions.
Publication
T. Juraschek, O. Weichold
Concrete 2019, 5, 168–171.
Electrochromy for the visualisation of small amounts of electricity
ABSTRACT: A disadvantage of current corrosion monitoring systems is the availability of suitable readout devices to predict the service life of the monitored structures. On-site, maintenance-free and easy-to-read units would be readable units would be advantageous for use. Against this background, a component has been developed that is capable of reading small visualise small amounts of current on the basis of electrochromics. The aim is is to detect corrosion currents and to display them visually. visual representation. The article describes the structure of the component, its electrochemical electrochemical characterisation and the visualisation of corrosion corrosion currents under laboratory conditions and on real corroding reinforced reinforced concrete test specimens.
Publication
C. Morales Cruz, Oliver Weichold, H.-J. Kocks
Concrete 2019, 5, 162–167.
FOULPROTECT - on the problem of fouling in seawater structures
ABSTRACT: As part of the joint project FOULPROTECT "Protection against fouling and prevention of biocorrosion in maritime technology", a mineral coating with increased mechanical resistance for steel structures in seawater was developed at the Institute for Construction Research at RWTH Aachen University (ibac) in cooperation with the companies Salzgitter Mannesmann Line Pipe GmbH (SMLP) and LimnoMar. The suitability of various commercially available factory dry mortars as protective coatings was tested using the example of steel pipes for foundation structures of offshore wind turbines. For this purpose, the fresh and hardened mortar characteristics were determined and durability tests were carried out in laboratory tests under real conditions (air and seawater storage). Growth (biofouling) on the mortar coating during seawater storage could not be prevented in any of the materials tested, but fluorescence microscopic examinations showed neither micro- nor macro-colonisation below the mortar surface. Significant differences in the number of cracks in the aged samples were found between the individual materials. Taking all investigations into account, high-strength mortar mixtures show the greatest potential to permanently withstand abrasive impacts and internal blast pressures.
Publication
P. B. Sassmann, O. Weichold
Ionics 2019
To the article→
Preparation and characterisation of ion-conductive unsaturated polyester resins for the on-site production of resistivity sensors
ABSTRACT: Ion-conductive unsaturated polyesters were synthesised from poly(ethylene oxide) and maleic anhydride for use in the development of improved methods for the structural-health monitoring of infrastructural buildings. The unsaturated polyesters (UP) were cross-linked with styrene using a redox initiator in the presence of LiClO4. Electrochemical impedance-spectroscopy was used to study the effects of initiator and styrene concentration as well as the EO:Li+ ratio. Increasing the initiator or styrene content results in an increased resistivity of the final materials. Cross-linking with styrene does not appear to cause microphase separation into pure UP and polystyrene phases, since the resulting resistivities are significantly lower than predicted by the rule of mixtures. For all temperatures under investigation (0 °C to 60 °C), the lowest resistivities were found for a EO:Li+ ratio of 50 (400 Ω·m at 22 °C), which is in accordance with previous findings. The electrical properties of the present materials are determined by diffusion controlled process in such a way polarisation prevails at high temperatures. In a proof of principle experiment, one selected UP formulation was injected into drill holes in concrete and cured at different temperatures and moisture conditions. This system reliably monitors the resistivity against an embedded reference electrode.
Publication
M. B. Endres, O. Weichold
Carbohydrate Polym. 2018
To the article→
Sorption-active transparent films based on chitosan
ABSTRACT:
In this paper we describe the preparation of alkanoic acid-based
aqueous chitosan solutions, which show no sign of acid-catalysed
depolymerisation over time – something commonly accompanying other
preparation methods. Longer chitosan chains have previously been shown
to exhibit more advantageous biological activities, and constant
viscosities are essential for consistent quality in biomedical
applications. Avoiding acid-catalysed depolymerisation requires careful
control of the stoichiometry between the free amino groups of chitosan
and the appropriate solubilising acid. Acetic and butyric acid are both
suitable solubilising agents, but chitosan butyrate exhibits lower
solution viscosities due to a combined electric and steric shielding of
the chains.
These solutions dry into clear transparent films that
remain fully water soluble and absorb up to 70 wt% of water from 90 %-RH
vapour phase at 25 °C. The absorption follows simple first-order
kinetics and the rate constants increase with increasing humidity up to
approx. 71 %-RH, where a metastable chitosan trihydrate salt appears to
be formed. Desorption is slightly faster, but more complex, as it
exhibits two distinct first-order processes. In addition, films prepared
in this way are thermally more stable than the usual chitosan
hydrochloride.

Front page
A. Jung, O. Weichold
Andre's publication "Preparation and characterisation of highly alkaline hydrogels for the re-alkalisation of carbonated cementitious materials" was selected by Soft Matter for the cover design.
Bachelor thesis
Lutz Burow
Congratulations on the successful completion of the bachelor thesis
Untersuchung der thermischen Eigenschaften von mit Keratin imprägnierten Holzspänen
Thermal properties of keratin-impregnated chipped wood
Lecture
O. Weichold
IBAUSIL, Weimar, 12.–14. September 2018
Polymere und Beton – Eine wilde Ehe mit Potential
Bachelor thesis
Lena Schmitz
Congratulations on the successful completion of the bachelor thesis
Vernetzte Polyethylenglycole als Träger für ionenleitfähige Filme
Cross-linked polyethylene glycol matrix for ion-conductive films
Master thesis
Jan Tenbusch
This master's thesis was carried out externally in cooperation with Henkel. Congratulations on the successful completion.
Bachelor thesis
Kathrin Dahm
Congratulations on the successful completion of the bachelor thesis
Synthese ethoxylierter und propoxylierter Styrole zur Herstellung ionisch leitfähiger Polyester
Synthesis of ethoxylated and propoxylated styrene for the formation of ionic conductive polyesters
Bachelor thesis
Julia Littke
Congratulations on the successful completion of the bachelor thesis
Synthese ungesättigter Polyester auf Basis von PPO
Synthesis of unsaturated polyesters based on PPO

Publication
A. Jung, O. Weichold
Soft Matter. 2018
To the article→
Preparation and characterisation of highly alkaline hydrogels for the re-alkalisation of carbonated cementitious materials
ABSTRACT:
Highly alkaline hydrogels that allow the restoration of alkaline buffer
in cementitious materials can be obtained from diallyldimethylammonium
hydroxide. The latter must be prepared in dilute solutions and
polymerised at ambient temperatures in order to avoid decomposition.
Using methacrylamide as a neutral co-monomer capable of forming hydrogen
bonds, the rheological properties of the gels can be adjusted over a
wide range; e.g. the viscosity increases a thousandfold from 0.35 Pa·s
to 4350 Pa·s by using 10 mol% methacrylamide. For the proof of principle
experiments, gels with 9 mol% methacrylamide were used, which contain
approx. 1.6 mol hydroxide ions per kg gel. Ion exchange between this and
a neutral chloride containing gel provided an apparent diffusion
coefficient of 4.12·10−7 m2 s−1 for the hydroxide ions and confirmed the
transport of chloride ions into the alkaline gel. The re-alkalisation
was tested on fully carbonated mortar prisms made from Portland cement.
Re-alkalisation of the mortar was confirmed by the phenolphthalein test
according to DIN EN 14630:2007-01 and by a control experiment with pure
calcium carbonate using IR spectroscopy.
Bachelor thesis
Jan Bandowski
Congratulations on the successful completion of the bachelor thesis
Entwicklung von Steuerungsmechanismen zur Regulierung der viskosen Eigenschaften eines PolyDADMAC-Gels
Development of mechanisms to control the viscous properties of PolyDADMAC gels
The work was carried out together with the FH Aachen, Department of Chemistry and Biotechnology.
Publication
T. Juraschek, O. Weichold
J. Phys. Org. Chem. 2017; e3739
To the article→
Development of an electrochromic device triggered by the macrocell current in chloride-induced corrosion of steel-reinforced concrete
ABSTRACT: This article presents the development and characterisation of an electrochromic device and its application to detect steel corrosion in reinforced concrete. Steel corrosion inflicts an enormous annual economic damage, which could be reduced by the installation of appropriate monitoring devices. These should be simple, reliable, long lasting, and should not require service or maintenance. The present electrochromic device is constructed in such a way that it uses the macrocell current in an active, chloride‐induced corrosion element as power supply to trigger the colour change. This way, the system stays inactive until corrosion occurs. The device consists of diheptyl viologen in a liquid polymer electrolyte made from LiClO4 and poly(ethylene glycol) with Mw = 400 g mol−1. The addition of viologen lowers the resistance but causes no further changes in the electrochemical properties of the polymer electrolyte. Impedance spectra indicate ion transport rather than capacitance effects to dominate the electrochemical properties. Experiments using direct current in the microampere range show electrochromic switching times of several minutes, which is sufficient for the intended monitoring application.
Lecture
M. Brenner
Tagung der GDCh-Fachgruppe Bauchemie, Weimar, 19. September 2017
Functionalisation of fibre surfaces for textile-reinforced elastomers
ABSTRACT: Decisive for the load-bearing capacity of textile-reinforced structures is the performance of the interface. In cementitious systems, this is usually achieved by form-fit joints (e.g. carbon textiles impregnated with epoxy resin and sanded). In polymeric materials, such a stiff bond is often undesirable due to the smaller modulus of elasticity, and in elastomers it is even counterproductive. The presentation reports on an investigation into the targeted chemical functionalisation of glass, basalt and carbon fibres to reinforce chloroprene and EPDM. The fibres were modified with bis[3-(triethoxysilyl)propyl]tetrasulphide (TESPT) and 3-(mercaptopropyl)trimethoxysilane (3-MPTMS). For application, the substances were mixed with dissolved elastomer and applied to the fibres by hand. The modified fibres were then vulcanised into the elastomer in a specially manufactured mould and the fibre-matrix adhesion was tested in a pull-out test. With glass and basalt fibres, an improvement in the bond of up to approx. 100 % could be achieved; with the modification of carbon fibres, the bond can be improved by approx. 50 %.
Lecture
O. Weichold
Tagung der GDCh-Fachgruppe Bauchemie, Weimar, 19. September 2017
Polymere im Bauwesen – weiche Materialien in einer harten Welt
Publication
O. Weichold, U. Antons
J. Infrastruct. Syst. 2017, 23, 04017010
To the article→
Assessing the Performance of Hydrophobing Agents on Concrete using Non-Destructive Single-Sided Nuclear Magnetic Resonance
ABSTRACT: Single-sided nuclear magnetic resonance is a nondestructive analytical technique by which the ingress behavior of hydrophobing agents as well as the properties and performance of the resulting hydrophobic layers can be assessed quantitatively. The method is used to compare the behavior of two low-molecular-weight hydrophobing agents, n-octyltriethoxysilane and i-butyltriethoxysilane, on concrete and to assess the properties of the resulting hydrophobic layers. For the octyl derivative, ingress appears to be a simple transport process without pronounced polycondensation in the liquid phase or reaction with the pore walls because the detectable amount stays rather constant during the first day of observation. In addition, the thickness of the resulting hydrophobic layer correlates well with the endpoint of the transport process. In contrast, the detectable amount of the butyl derivative is reduced to half during the first 18 h, indicating either substantial polycondensation or anchoring to the pore walls, and the hydrophobic layer is approximately 25% thicker than indicated by the ingress profiles. The different behavior could originate in differences in the molecular structure, particularly the steric demand of the alkyl substituents, although this requires a more detailed study. Both compounds proved to be excellent hydrophobing agents since the layers were found to be impermeable when kept in a shallow water bath (unidirectional transport through the layer) for more than 1 year. The results demonstrate that single-sided nuclear magnetic resonance is an excellent nondestructive tool for quality assurance when applying such protective layers.
Lecture
T. Juraschek
EUROCORR 2017, Prag, 3. September 2017
Chemical, Non-Electronic Corrosion Indication Systems
ABSTRACT:
Corrosion of the steel reinforcement in concrete causes an enormous
economic damage. In particular, chloride-induced macroelement corrosion
of the reinforcement is one of the bottlenecks in the service life time
design of a majority of infrastructure buildings with a significant
exposition to chloride. Corrosion monitoring offers a possibility to
detect the onset of corrosion events and start independent restoration
actions at a point, where costs can be kept at a minimum.
The
presentation focusses on the testing procedure and verification of the
prototype, under conditions simulating real-life corrosion events. Color
change is not observed when applying zero-load currents, but occurs
within minutes after raising either the potential or current to levels
typical for corrosion events. The color change is persistent even after
turning the power source off. We applied potential controlled current
profiles as well as voltage controlled current profiles to the device,
also with respect to peak current profiles to show the response of the
system under realistic circumstances. Also, we investigate the influence
of zero-load current and voltage events during the passive state of the
reinforcement steel after passivation. Furthermore, experiments on
reinforcement steel and reinforced concrete samples are shown as a
proof-of-principle experiment.
Publication
R. Schulte Holthausen, O. Weichold
J. Infrastruct. Syst. 2017, 23, B4016006.
To the article→
Non-destructive Evaluation of Thermal Damage in Concrete by Single-Sided Nuclear Magnetic Resonance
ABSTRACT: A new technology to coat concrete with coherent layers of glass by flame-spraying is currently developed at the Institutes of Building Materials Research and Mineral Engineering of RWTH Aachen University in Germany through a joint program. A major factor influencing the pull-off strength of the flame-sprayed glass coating is thermally induced damage in the underlying concrete substrate. In this article, the authors present a nondestructive test method using single-sided 1H nuclear magnetic resonance (NMR) to evaluate the thermally induced damage in concrete specimens. The particular NMR device used in this project primarily detects water and can qualitatively assess the water content as well as the relative size of water-filled voids such as pores and cracks. To do so, the specimens are water saturated and subsequently analyzed by NMR. Changes in the NMR-signal are interpreted in terms of change in porosity and development of cracks inside the cement stone as a function of depth from the concrete surface.
Bachelor thesis
Iva Rroshi
Congratulations on the successful completion of the bachelor thesis
Zur Untersuchung der Genauigkeit bei der Ermittlung des Bindemittelgehalts an Betonproben durch Methoden der chemischen Analytik
Investigation
of the accuracy conerning the determination of the binder content of
concrete samples by methods of analytical chemistry
Master thesis
Markus Brenner
Congratulations on the successful completion of the Master's thesis
Funktionalisierung von Faseroberflächen für textilbewehrte Elastomerlager
Functionalization of Fiber Surfaces for Textile-Reinforced Elastomeric Bearings

Lecture
O. Weichold
Seminar „Stadtstraßen / Ortsdurchfahrten“ des VSVI Niedersachsen e.V., ABZ Mellendorf, 25. Januar 2017
CARPET – Konfektionierter, aufrollbarer, polymerbasierter Straßenbelag
Konferenzbeitrag
T. Juraschek, O. Weichold
6th International Conference on Concrete Repair (Concrete Solutions), Thessaloniki, 2017, S. 207–211.
In-situ methods of detecting steel corrosion using permanent and non-electronic systems
ABSTRACT: Current systems for detecting corrosion of the reinforcement in concrete are realized via highly specialized systems that are commercially not available. Thus, these systems require complete technical support by the installing company. This report shows a cheap, efficient, independent, and reliable method to detect corrosion events in concrete. The detection system is based on an electrochromic device, which changes its colour upon the change of electrochemical potential caused by the corrosion process. The device is realized by a layer-by-layer setup of a transparent electrode, e. g. indium-doped tin oxide (ITO), followed by an electrochromic layer. The system is closed by a metal counter electrode. The electrochromic layer can consist of an electrochromic compound in a conducting polymer system. By connecting such elements to a series of sensors, e. g. an anode ladder, it is possible to monitor the corrosion progress and to verify the service life design of a structure.
Konferenzbeitrag
P. B. Sassmann, O. Weichold
6th International Conference on Concrete Repair (Concrete Solutions), Thessaloniki, 2017, S. 235–238.
Development
of Electrically Conductive Resins for the On-Site Fabrication of
Sensors for Corrosion Detection and Risk Assessment in Reinforced
Concrete
ABSTRACT: Assessing the risk of corrosion in steel-reinforced concrete can be accomplished using different types of sensors such as anode ladders or multi-ring electrodes. The former are unsuitable for retrofit installations, while the latter require the use of embedding mortars to achieve conductive connections with the surrounding concrete. However, the porosity of the embedding mortar differs from that of the concrete and the retrofitting action introduces additional moisture. This interferes with resistivity and/or potential measurements and makes interpretations of the actual situation problematic. To circumvent these disadvantages, we have developed a liquid reactive polymer resin with high electrical conductivity that can be used to fabricate sensors directly inside drill holes. The mixture solidifies in a short time and its adhesive properties provide an excellent conductive connection to the concrete walls. The resin contains no water so that reliable values can be obtained immediately after solidification. By changing the additives both resistivity and potential sensors can be obtained. The mixture is cheap so that large sensor networks can be installed at reasonable costs. Such networks are ideal for the precise localization of corrosion events and more importantly for risk assessment in steel-reinforced structures.

Lecture
O. Weichold
nuBau – 3. Tagung Nutzerorientierte Bausanierung, Weimar, 30. November – 1. Dezember 2016
Neue Methoden zur Auswertung von Sw-ρ-Beziehungen
ABSTRACT: The electrical resistivity of concrete is often used to make statements about the durability of reinforced concrete structures. The aim of the presented investigations is to characterise water content-resistivity relationships as a function of relevant structural parameters of the concrete. For this purpose, an approach based on Archie's law was chosen, the results of which are presented and compared with the commonly used model. An attempt is made to cone selected parameters with the properties of the pore system of the concretes and thus to demonstrate the possibilities of the presented approach.
Lecture
P. B. Sassmann
2nd International Conference on the Chemistry of Construction Materials (ICCCM), München, 10.–12. Oktober 2016
Development of ion- conductive polymer resins for the on-site fabrication of corrosion sensors
ABSTRACT:
Assessing the corrosion risk in steel-reinforced concrete can be
accomplished by implementing monitoring systems. For retrofit
installations the electrically conductive connection of sensors and
surrounding concrete is currently realised with cement-based embedding
mortars. The use of such aqueous systems changes the moisture content of
the concrete close to the sensor, which interferes significantly with
resistivity and/or potential measurements and makes interpretations of
the measured values problematic.
To circumvent these disadvantages,
we developed a liquid, reactive, non-aqueous polymer resin with high
electrical conductivity that can be used to fabricate sensors directly
inside drill holes. This way, a close contact between sensor and the
concrete walls is automatically provided. Since the polymer resin is not
aqueous, the moisture balance of the old concrete is not altered so
that reliable values can be obtained immediately after solidification.
Buchbeitrag
J.-P. Lecomte, O. Weichold
in Y. Liu (Ed.), Silicone Dispersions (Surfactant Science Series Vol. 159), CRC Press, Boca Raton, 2016, S. 301–331.
Silane-based Water Repellents for Inorganic Construction Materials
Master thesis
Pia B. Sassmann
Congratulations on the successful completion of the Master's thesis
Ionenleitende ungesättigte Polyester zur Ankopplung von Zulagekathoden in Beton
Ion-conductive unsaturated polyester for contacting galvanic couples in concrete
Publication
D. Heinze, Th. Mang, C. Popescu, O. Weichold
Thermochim. Acta 2016, 637, 143–153
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Effect
of side chain length and degree of polymerization on the decomposition
and crystallization behaviour of chlorinated poly(vinyl ester) oligomers
ABSTRACT:
Four members of a homologous series of chlorinated poly(vinyl ester)
oligomers CCl3–(CH2CH(OCO(CH2)mCH3))n–Cl with degrees of polymerization
of 10 and 20 were prepared by telomerisationusing carbon tetrachloride.
The number of side chain carbon atoms ranges from 2 (poly(vinyl acetate)
to 18 (poly(vinyl stearate)). The effect of the n-alkyl side chain
length and of the degree of polymerizationon the thermal stability and
crystallization behaviour of the synthesized compounds was
investigated.All oligomers degrade in two major steps by first losing
HCl and side chains with subsequent breakdownof the backbone. The
members with short side chains, up to poly(vinyl octanoate), are
amorphous andshow internal plasticization, whereas those with high
number of side chain carbon atoms are semi-crystalline due to side-chain
crystallization. A better packing for poly(vinyl stearate) is also
noticeable.The glass transition and melting temperatures as well as the
onset temperature of decomposition areinfluenced to a larger extent by
the side chain length than by the degree of polymerization.
Thermalstability is improved if both the size and number of side chains
increase, but only a long side chaincauses a significant increase of the
resistance to degradation. This results in a stabilization of PVAc
sothat oligomers from poly(vinyl octanoate) on are stable under
atmospheric conditions. Thus, the way todesign stable, chlorinated PVEs
oligomers is to use a long n-alkyl side chain.
Bachelor thesis
Tim Kurschildgen
Congratulations on the successful completion of the bachelor thesis
Einfluss der Copolymerisation funktioneller Monomere im Porenraum auf die mechanischen Eigenschaften von Mörtel
Copolymerisation of functional monomers in the pore system of mortars and its influence on the mechanical properties
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