Filtern
Erscheinungsjahr
Dokumenttyp
- Beitrag zu einem Tagungsband (78)
- Zeitschriftenartikel (49)
- Beitrag zu einem Sammelband (37)
- Vortrag (22)
- Buchkapitel (8)
- Posterpräsentation (5)
- Sonstiges (2)
- Forschungsbericht (1)
Sprache
- Englisch (104)
- Deutsch (97)
- Mehrsprachig (1)
Schlagworte
- Beton (20)
- UHPC (14)
- Rheology (13)
- Concrete (12)
- Baustoffe (11)
- Zement (10)
- AKR (9)
- Durability (8)
- Self-compacting concrete (7)
- Alkali-Kieselsäure-Reaktion (6)
- Microstructure (6)
- Repair mortar (6)
- Acoustic emission (5)
- Alkali-silica reaction (5)
- Betoninstandsetzung (5)
- Building Materials (5)
- Dauerhaftigkeit (5)
- Hochleistungsbeton (5)
- Instandsetzungsmörtel (5)
- Nachhaltigkeit (5)
- Nanotechnologie (5)
- Polycarboxylate ether (5)
- Polypropylene fibres (5)
- Repair systems (5)
- Rheologie (5)
- Schallemissionsanalyse (5)
- Thermal treatment (5)
- Autogenes Schwinden (4)
- Concrete rehabilitation (4)
- Degradation (4)
- Gefüge (4)
- High performance concrete (4)
- Hydrothermal treatment (4)
- Modulare Systeme (4)
- Polycarboxylate (4)
- Sekundäre Gesteinskörnung (4)
- Setting (4)
- Shrinkage (4)
- Versuche (4)
- Zonation (4)
- ASR (3)
- Analytik (3)
- Bindemittel (3)
- Cement paste (3)
- Fließmittel (3)
- Hydratation (3)
- PCC (3)
- Polycarboxylatether (3)
- Polymer cement concrete (PCC) (3)
- SPCC (3)
- Scanning electron microscopy (3)
- Secondary aggregates (3)
- Sekundärrohstoffe (3)
- Selbstverdichtender Beton (3)
- Sprayed polymer cement concrete (SPCC) (3)
- Stabilising agent (3)
- Starch ether (3)
- Sustainability (3)
- Temperature (3)
- Tobermorite (3)
- Ultrasound (3)
- X-ray diffraction (XRD) (3)
- Accelerated concrete prism test (2)
- Admixtures (2)
- Adsorption (2)
- Alkali silica reaction (2)
- Architectural Concrete (2)
- Autoclaving (2)
- Autoklavierung (2)
- Automated expansion measurement (2)
- Betonangriff (2)
- Betonbrechsand (2)
- Betontechnologie (2)
- Bewertung (2)
- Biopolymers (2)
- C-S-H (2)
- C-S-H Phasen (2)
- Cement (2)
- Cementitious materials (2)
- Compressive strength (2)
- Computed tomography (2)
- Concrete analysis (2)
- Cyclic loading (2)
- Damage analysis (2)
- Desiccation (2)
- Digitalisierung (2)
- Einzelfaserdurchzugsversuch (2)
- Ermüdung (2)
- Ettringit (2)
- Facade Elements (2)
- Fasermodifikation (2)
- Fatigue (2)
- Festigkeit (2)
- Fibres (2)
- Forschung und Entwicklung (2)
- Grenzflächenaktive Verbindung (2)
- Heat evolution (2)
- Heat treatment (2)
- High temperatures (2)
- Hydraulic engineering structures (2)
- Hydroxylellestadite (2)
- Korrosion (2)
- Lichtmikroskopie (2)
- Mechanical strength (2)
- Mikrostruktur (2)
- Mineral additions (2)
- Mixture composition (2)
- Modellierung (2)
- Modified starch (2)
- Müllverbrennungsasche (2)
- Müllverbrennungsaschen (2)
- Natürliche puzzolanische Zusatzstoffe (2)
- Oberflächenfunktionalisierung (2)
- Phasenzusammensetzung (2)
- Polymer cement mortar (PCC) (2)
- Polypropylen-Fasern (2)
- Polysaccharides (2)
- Porenstruktur (2)
- Portland cement (2)
- Radar (2)
- Rasterelektronenmikroskopie (2)
- Recycling (2)
- Robustheit (2)
- Robustness (2)
- Röntgen-3D-Computertomographie (2)
- SCC (2)
- Schwinden (2)
- Secondary materials (2)
- Self-Cleaning Properties (2)
- Spalling (2)
- Sprayed polymer cement mortar (SPCC) (2)
- Stabilising agents (2)
- Sulfatangriff (2)
- Superplasticizer (2)
- Superplasticizers (2)
- Sustainable evaluation (2)
- Säureangriff (2)
- Thermal strain (2)
- Ultra-High Performance Concrete (UHPC) (2)
- Ultra-high performance concrete (2)
- Ultraschall (2)
- Windkanal (2)
- Wärmebehandlung (2)
- XRD (2)
- Yield stress (2)
- Zementgebundene Baustoffe (2)
- Zusatzstoffe (2)
- alkali-silica-reaction (2)
- 60 °C-Betonversuch (1)
- 60 °C-CPT (1)
- 60° C-Betonversuch (1)
- ASR damage (1)
- ASR expansion monitoring (1)
- ASR modelling (1)
- Accelerated testing (1)
- Acoustic emissions analysis (1)
- Adhesive Pull-Strength (1)
- Aggregate (1)
- Alite (1)
- Alkali-Silica Reaction (1)
- Alkali-silica-reaction (1)
- Alkali–silica reaction (1)
- Allgemeines (1)
- Altpapierrecycling (1)
- Anti-Graffiti (1)
- Anti-graffiti agent (1)
- Anwendungsbeispiele (1)
- Assessment (1)
- Assessment concept (1)
- Auslaugung (1)
- Autoclaved aerated concrete (1)
- Autogenous deformation (1)
- Automated testing (1)
- Automatische Dehnungsmessung (1)
- BOFS (1)
- Baustellenanwendung (1)
- Baustoff (1)
- Bauwerksdiagnose (1)
- Bauwerkssicherheit (1)
- Behandlungsparameter (1)
- Beton mit geringer Festigkeit (1)
- Betonfahrbahndecke (1)
- Betonfahrbahndecken (1)
- Betonfahrdecke (1)
- Betonfertigteil (1)
- Betonstahl (1)
- Betontechnik (1)
- Betonzusatzstoff (1)
- Biofilm (1)
- Biomasseasche (1)
- Biomasseverbrennung (1)
- Bioreceptivity (1)
- Blended cement (1)
- Brand (1)
- Brandschutz (1)
- Brandverhalten (1)
- Brick (1)
- Brown coal fly ash (1)
- Building and Construction (1)
- CFD (1)
- Calorimetry (1)
- Carbonation (1)
- Cement hydration (1)
- Chemischer Angriff (1)
- Chloride attack (1)
- Chloride ingress (1)
- Cleaning efficacy (1)
- Climate simulation concrete prism test (1)
- Coarsely dispersed systems (1)
- Compatibility (1)
- Composition (1)
- Compressive Cyclic loading (1)
- Compressive strenght (1)
- Computertomografie (1)
- Computertomographie (1)
- Concentration (1)
- Concrete (E) (1)
- Concrete Prism Test at 60 °C (1)
- Concrete motorway pavements (1)
- Concrete pavement (1)
- Concrete pavements (1)
- Concrete petrography (1)
- Concrete's porosity (1)
- Continuous monitoring (1)
- Cultural Heritage (1)
- Cyclic traffic loading and mechanical pre-damage (1)
- Datenmanagement (1)
- Degradation (C) (1)
- Dehnungsmessung (1)
- Denkmalpflege (1)
- Developing building materials (1)
- Diutan gum (1)
- EDX (1)
- Early cement hydration (1)
- Edelstahlschlacke (1)
- Eigenschaften (1)
- Einsatzpotenzial (1)
- Elevated temperatures (1)
- Energy and material resources (1)
- Environmental conditions (1)
- Ermüdungsverhalten (1)
- Erstarren (1)
- Ettringite (1)
- Expansion modelling (1)
- External alkalis (1)
- FAIR-Prinzip (1)
- Fahrbahn (1)
- Fahrbahndeckenbetone (1)
- Fassaden (1)
- Fast measurement (1)
- Fatigue loading (1)
- Festigkeitssteigerung (1)
- Filterrückstand (1)
- Fire (1)
- Fire Spalling (1)
- Fire resistance (1)
- Fire safety design (1)
- Flexural testing (1)
- Flow of concrete (1)
- Flow of mortar (1)
- Fluid transport (1)
- Flüssigkeitstransport (1)
- Fracture energy (1)
- Freezethaw resistance (1)
- Fresh concrete (A) (1)
- Frischbeton (1)
- Frischbetoneigenschaften (1)
- Frost-Tausalz-Beanspruchung (1)
- Frühe Rissbildung (1)
- Frühe Zementhydratation (1)
- Functionalization (1)
- General Materials Science (1)
- Gesteinskörnung (1)
- Graffiti (1)
- Green facades (1)
- HPC (1)
- HRWRA (1)
- HSC (1)
- Haftverbund (1)
- Haltezeit (1)
- Herstellungsprozesse (1)
- High resolution (1)
- High strength concrete (1)
- High-strength concrete (1)
- Hochfester Beton (1)
- Hochleistungsbetone (1)
- Holistic concept (1)
- Hydratationswärme (1)
- Hydration products (1)
- Hydraulisch (1)
- Hydrogarnet (1)
- Hydrogranat (1)
- Hydrophobic surfaces (1)
- Hydrophobic treatment (1)
- Hydrothermale Behandlung (1)
- Hydroxyellestadit (1)
- Impregnation (1)
- In-situ (1)
- In-situ XRD (1)
- Industrieabwasseraufbereitung (1)
- Industrielle Reststoffe (1)
- Influence of temperature (1)
- Innovative Prüftechnik (1)
- Instandsetzung (1)
- Instandsetzungssysteme (1)
- Internal sulfate resistance (1)
- Ionentransport (1)
- Kesselsand (1)
- Kristalline CSH-Phase (1)
- LD-Schlacke (1)
- LIBS (1)
- Laser-induced breakdown spectroscopy (1)
- Laser-induced breakldown spectroscopy (1)
- Leaching of alkalis (1)
- Leistungsfähigkeit (1)
- Limestone (1)
- Listed buildings and monuments (1)
- Low strength concrete (1)
- MRFA (1)
- Materialdaten (1)
- Materials characterisation (1)
- Mechanische Vorschädigung (1)
- Messtechnik (1)
- Metadaten (1)
- Metallurgie (1)
- Micro X-ray fluorescence analysis (1)
- Micro chemical analysis (1)
- Micro cracks (1)
- Micro structure (1)
- Micro texture (1)
- Micro-Crack (1)
- Microcracks (1)
- Microfiller (1)
- Microscopy (1)
- Mikrofiller (1)
- Mikromechanik (1)
- Mikrorissbildung (1)
- Mikrorisse (1)
- Mineralogie (1)
- Mineralogische Zusammensetzung (1)
- Mischungsentwurf (1)
- Mitigation strategies (1)
- Modeling (E) (1)
- Modelling (1)
- Modular system (1)
- Modular systems (1)
- Moisture clog (1)
- Moisture transport (1)
- Monitoring (1)
- Monitoring of damage (1)
- Mortar (1)
- Mörtel (1)
- NDT (1)
- NMR (1)
- Nachbehandlung (1)
- Nasschemie (1)
- Natural pozzolans (1)
- Natural stone (1)
- Naturstein (1)
- Natürliche Pozzolane (1)
- Nebelkammerlagerung bei 40° C (1)
- Non destructive testing (1)
- Non-destructive testing (1)
- On-Site Application III (1)
- Ontologie (1)
- Ontologien (1)
- Optical microscopy (1)
- Oscillation rheometry (1)
- PP-Fasern (1)
- Papierasche (1)
- Pavement (1)
- Pavement concrete (1)
- Performance (1)
- Performance test (1)
- Performance tests (1)
- Permeability (C) (1)
- Phase composition (1)
- Phase development (1)
- Phase stability (1)
- Photogrammetric analysis (1)
- Plastisches Schwinden (1)
- Polycarboxylate ether vicat (1)
- Polycarboxylate superplasticizer (1)
- Polymer-Zement Beton (PCC) (1)
- Polymer-Zement Spritzbeton (SPCC) (1)
- Polypropylene Fibres (1)
- Polypropylene fibers (1)
- Pore structure analysis (1)
- Portland Cement (1)
- Portland cement Initial hydration (1)
- Praxis (1)
- Preparation of thin sections (1)
- Production technology (1)
- Prüfmethoden (1)
- Puzzolane (1)
- Quasi non-destructive assessment (1)
- Raman microscopy (1)
- Rezyklierte Gesteinskörnung (1)
- Rheology (A) (1)
- Rissbildung (1)
- Risse (1)
- Road pavement (1)
- Röntgen 3D-Computertomographie (1)
- Röntgen-Computertomografie (1)
- Sample holder (1)
- Schadensanalyse (1)
- Schallemissionsprüfung (1)
- Schrumpfrisse (1)
- Schädigende AKR (1)
- Schädigungsprozesse (1)
- Secondary aggregates in concrete (1)
- Secondary cemetitious materials (1)
- Sekundärstoff (1)
- Self-Compacting Concrete (1)
- Self-consolidating concrete (1)
- Silanes (1)
- Silikastaub (1)
- Simulation (1)
- Slump flow (1)
- Spannstahl (1)
- Spatial analyses (1)
- Sphingan (1)
- Stabilizer (1)
- Stahlfasern (1)
- Starch (1)
- Steelmaking slag (1)
- Stofftransport (1)
- Stone (1)
- Stone reprofiling (1)
- Stone restoration (1)
- Strain hardening (1)
- Straßenbeton (1)
- Stress-strain-relation (1)
- Structural fire protection (1)
- Sulfate attack (C) (1)
- Sulphate attack (1)
- Sulphate-chloride attack (1)
- Superplaticizer (1)
- Surface interactions (1)
- Surface protection system (1)
- Sustainability aspects (1)
- Sustainable building (1)
- Synchrotron (1)
- Tausalz (1)
- Temperatur (1)
- Temperatureffekte (1)
- Tensile strength (1)
- Test methods (1)
- Thermal analysis (1)
- Thermo mechanical behaviour (1)
- Thermodynamik (1)
- Tobermorit (1)
- Traffic (1)
- Transient strain (1)
- Transport mechanism (1)
- Transport process (1)
- Transportprozess (1)
- Transportprozesse (1)
- Tricalcium-silicate (1)
- Tricalciumsilikat (1)
- Ultra high performance concrete (1)
- Ultra-High Performance Concrete (1)
- Ultra-High-Performance Concrete (1)
- Ultra-Hochleistungsbeton (1)
- Ultrahigh-performance concrete (1)
- Ultrahigh-performance concrete (UHPC) (1)
- Ultrahochleistungsbeton (1)
- Ultraschallgeschwindigkeit (1)
- Ultrasonic and ray (1)
- Ultrasonic testing (1)
- Ultrasonic velocity (1)
- Verformung (1)
- Verkehr (1)
- Verwertungspotential (1)
- Vicat (1)
- Viscoelastic properties (1)
- Viscosity (1)
- Viscosity modifying agents (1)
- Vorlagerungszeit (1)
- Vorschädigung (1)
- Wasserbau (1)
- Water content (1)
- Water uptake (1)
- Water/cement ratio (1)
- Weathering (1)
- Wettability (1)
- Wissengraph (1)
- X-Ray diffraction (1)
- X-ray CT (1)
- X-ray computed tomography (1)
- X-ray diffraction (1)
- X-ray diffraction (B) (1)
- X-ray diffractometry (1)
- Zerstörungsarme und zerstörungsfreie Prüfverfahren (1)
- Zerstörungsfreie Prüfung (1)
- ZfP (1)
- Zonierung (1)
- Zumahlstoff (1)
- Zusatzmittel (1)
- Zyklische Belastung (1)
- Zyklischen Belastung (1)
- autoclaving (1)
- building materials (1)
- concrete (1)
- concrete pavements (1)
- damage monitoring (1)
- durability (1)
- end-of-life phase (1)
- fatigue (1)
- gas permeability (1)
- heat treatment (1)
- masonry (1)
- mu-3D-CT (1)
- sustainability (1)
- zyklische Belastung (1)
- Äußere Alkalizufuhr (1)
- Ökobilanz (1)
Organisationseinheit der BAM
- 7 Bauwerkssicherheit (38)
- 7.1 Baustoffe (38)
- 4 Material und Umwelt (5)
- 7.4 Baustofftechnologie (5)
- 4.4 Thermochemische Reststoffbehandlung und Wertstoffrückgewinnung (4)
- 7.7 Modellierung und Simulation (2)
- 4.0 Abteilungsleitung und andere (1)
- 7.0 Abteilungsleitung und andere (1)
- 7.2 Ingenieurbau (1)
Paper des Monats
- ja (1)
Eingeladener Vortrag
- nein (22)
Baustoffe
(2002)
A sustainable approach for the conservation of the Timur Shah Mausoleum in Kabul, Afghanistan
(2005)
Der Einfluß der Mischungszusammensetzungen auf das frühe autogene Schwinden der Bindemittelmatrix von Hochleistungsbetonen wurde durch Korrelation mit der Hydratationskinetik untersucht. Durch die Analyse der Verformungsgeschwindigkeiten konnte eine Unterscheidung zwischen plastischen und spannungsinduzierenden Verformungen vorgenommen werden.
This paper presents the results of an
experimental study on the transient strain of high
strength concrete (HSC) under heating up to 750 °C
and the impact of polypropylene (PP) fibers. Concerning
this topic only few results are available in the
literature and systematic investigations are missing.
However, basic knowledge is necessary for the
understanding of the internal damage processes in
the material as well as for heated structures. The
transient strain during heating can be separated in two
basic components: the free thermal strain and the
mechanical strain. They were experimentally determined
exemplarily for one HSC. For the determination
of the mechanisms of transient strain and particularly
the influence of PP fibers different techniques were
applied. In this context the monitoring of the microcracking
was done for the first time with acoustic
emission analysis in combination with ultrasonic
measurements. This new approach helps fundamentally
to explain the impact of PP fibers on free thermal
strain and mechanical strain during heating up.
Furthermore weight loss measurements were carried
out to characterize the moisture transport. It was
shown that the PP fibers cause an acceleration of the
moisture transport in the temperature range from 200
to 250 °C which leads to drying shrinkage in opposite
direction to the free thermal strain. Hence this paper is
a contribution to the general understanding of the
impact of PP fibers in HSC at high temperatures and
emphasizes the important influence of PP fibers on the
thermal and mechanical induced strain of HSC.
Bauteile bzw. Tragwerke aus Hochleistungsbetonen müssen in der Regel gegen brandinduzierte Abplatzungen mit geeigneten Maßnahmen geschützt werden, um einen ausreichenden Feuerwiderstand im Brandfall zu gewährleisten. Die bisher wirtschaftlich und technologisch sinnvollste Methode zur Verhinderung von explosionsartigen Betonabplatzungen im Brandfall ist die Zugabe von Polypropylen-Fasern. Die Wirksamkeit der Fasern konnte zwar empirisch gezeigt werden, es stellt sich allerdings die Frage, welche Mechanismen zur Verhinderung der Abplatzungen führen. Der vorliegende Beitrag fasst bisherige Theorien zur Wirkungsweise von Polypropylen-Fasern in brandbeanspruchten Hochleistungsbetonen zusammen und stellt eine innovative Methodologie zur Erforschung der mikrostrukturellen Prozesse vor. Die Ergebnisse zeigen, dass die nach dem Schmelzen und Zersetzen der Polypropylen-Fasern frei werdenden Mikrokanäle durch eine gleichzeitig einsetzende Mikrorissbildung netzartig verbunden werden. Die Mikrorissbildung ermöglicht somit den Abbau von Eigen- und Zwangsspannungen im Beton (mechanischer Effekt) und die Entstehung eines Transportwegesystems für den ausströmenden Wasserdampf (Permeationseffekt).--------------------------------------------------------------------------- Structural members and bearing structures of high performance concrete generally have to be protected against explosive spalling due to fire exposure to guarantee a sufficient fire resistance. Up to now, the economically and technologically most worthwhile method to prevent explosive spalling is the addition of polypropylene fibres. Though the effectiveness of the fibres could be shown empirically, the mechanisms preventing explosive spalling are still debatable. The present article summarizes the existing theories concerning the mode of action of polypropylene fibres in fire exposed high performance concretes and presents an innovative methodology for analysing the micro structural processes. The results show that due to the thermal decomposition of the polypropylene fibres micro channels are created and simultaneously connected due to a netlike micro crack formation. This enables the relief of internal stresses (mechanical effect) and the formation of a permeable transport system for the escaping water vapour (permeation effect).
Sustainable evaluation - concept to assess the applicability of secondary aggregates in concrete
(2012)
Der Einsatz von Sekundärrohstoffen im Betonbau kann einen wesentlichen Beitrag zu einer nachhaltigen Ressourcenwirtschaft im Bauwesen leisten. Sekundärrohstoffe (Recycling-Baustoffe, RC-Baustoffe) finden bereits Anwendung als Roh- bzw. Brennstoffe in der Portlandzementklinkerherstellung, als Zementbestandteile, als Betonzusatzstoffe sowie als sekundäre Gesteinskörnungen in Beton. In einem Teilprojekt des DAfStb/BMBF-Verbundforschungsvorhabens 'Nachhaltig Bauen mit Beton' wurde das Einsatzpotenzial von Sekundärrohstoffen in Beton untersucht. Hierbei spielen sowohl technische als auch ökologische und ökonomische Fragestellungen eine wichtige Rolle. Vor diesem Hintergrund wurde eine Bewertungsgrundlage mit ganzheitlicher Betrachtung von Nachhaltigkeitsaspekten (Technik, Ökologie, Ökonomie) ausgearbeitet. Dieses Bewertungskonzept umfasst die vier Bewertungsschritte: I. Grundsätzliche Überlegungen, II. Vorteile für das nachhaltige Bauen, III. Alternative Bewertungswege und IV. Sensitivitätsanalysen. Das Bewertungskonzept wurde am Beispiel der bereits im Betonbau eingesetzten rezyklierten Gesteinskörnungen entwickelt.----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Nowadays there are several applications of secondary mineral materials and residues. In the framework of the German research project 'Sustainable Building with Concrete', a concept to assess the applicability of already used and new secondary materials in concrete has been developed. It considers sustainability aspects and includes the following four assessment steps: I. Basic considerations, II. Advantages for sustainable construction, III. Alternative paths of application, and IV. Sensitivity analysis. Depending on changing technical, ecological and economic aspects, the assessment has to be performed for changed technical, ecological and economic conditions as necessity arises.
Cultural Heritage objects are in many cases invaluable and irrecoverable, therefore their protection is a prior goal. One threat arises by intentionally defacing such objects with graffiti. One possibility to face the imminent threat is the application of a surface protection in form of anti-graffiti systems (AGS). However, the knowledge about the performance and durability of AGS on substrates used for historical buildings is still fragmented. The goal of the presented study was to investigate the performance of a newly developed agent in comparison to a selection of commercial anti-graffiti agents on different substrates, which were used for historical buildings. Four commercial anti-graffiti agents with different chemical formulations were selected and tested with the new agent on different stone and brick substrates. The results showed clearly that AGS based on dense, water vapour impermeable coatings are not suitable to porous substrates such as sandstone, brick or porous limestone due to their impair of the hygric properties and the visual appearance of a substrate. The new agent could not completely reach the cleaning efficacy of the dense coatings but exhibited a much lower impact on the properties of the substrate and was therefore better compatible to historical surfaces.
Repair mortars for the restoration and reprofiling of natural stone elements in cultural heritage
(2011)
For the protection of the world's cultural heritage the restoration of listed buildings and monuments is an important task. In many cases the need to repair and reprofile natural stone elements occurs. Repair mortars for such applications have to match historicocultural interests as well as durability related and constructive interests. Currently a research project dealing with the development and optimisation of such mortars is set up at the BAM. Special focus is laid on the possibility of a modular adaption to match a vast variety of stone properties. Besides the development and lab scale testing of the mortar system, an in-situ application will be planned and executed.
Nowadays there are several applications of mineral recycling materials and residues. At present an assessment method for the use of secondary raw materials, which considers sustainability aspects, does not exist. In the framework of the German DAfStb/BMBF research project 'Sustainable Building with Concrete' an assessment concept was developed. It includes the following four assessment steps: I. Basic considerations, II. Advantages for sustainable construction, III. Alternative paths for application, and IV. Sensitivity analysis. The concept was developed on the basis of recycled concrete aggregates, which are already used according to German standards. Afterwards, it was applied and verified by the evaluation of the utilisation of municipal solid waste incinerator bottom ashes.
Influence of selected aspects of the mixture proportioning on the performance of repair mortars
(2012)
Untersuchung des Einflusses der Gefügedichte von Betonen auf die AKR mit neuartiger Prüftechnik
(2011)
Trotz der zahlreichen Möglichkeiten zur Beeinflussung der Mörteleigenschaften durch Mischungsmodifikationen ist es nahezu unmöglich, einzelne Eigenschaften unabhängig von anderen zu verändern. Bei einer Mischungsoptimierung muss im Einzelfall immer entschieden werden, welcher der gewünschten Eigenschaften die höchste Priorität zukommt. Anhand von Parameterstudien wird im vorliegenden Artikel verdeutlicht, wie es für bestimmte Anwendungen sinnvoll sein kann, die Verschlechterung einzelner Eigenschaften zu akzeptieren, wenn dadurch eine für den speziellen Einsatzfall essenzielle Eigenschaft verbessert werden kann. Die komplexen Wechselwirkungen der einzelnen Bestandteile fuhren dazu, dass auch scheinbar widersprüchliche Kombinationen von Zusatzmitteln im Einzelfall erforderlich werden können. Zur Anpassung der meisten Mörteleigenschaften gibt es verschiedene Möglichkeiten der Zielerreichung mit jeweils unterschiedlichen Nebeneffekten. Frisch- und Festmörteleigenschaften sind dabei gleichermaßen zu beachten.
It has been shown in fire tests that polypropylene fibres reduce or avoid explosive spalling of high performance concrete. In the critical temperature ränge up to 300 °C the permeability of HPC increases by using polypropylene fibre. Due to this the water vapour, which is the main reason for explosive spalling, can escape. There exist different theories in the literature conceming the micro structural mechanisms, which cause an increase in the permeability. Within the framework of an internal research project at BAM an innovative methodology was developed for experimental verifying of existing theories and to get new insights into this problem The methodology used is unique and has been undertaken here for the first time. This consists of the combination of acoustic emission and ultrasonic measurement during temperature loading and the non-destructive micro structural analysis of cooled down samples with the aid of micro X-ray computed tomography. For the validation of the nondestructive test methods scanning electron microscopic images of prepared samples were undertaken. The results show that due to the thermal decomposition of the polypropylene fibres micro canals emerge. These are connected due to a simultaneous micro cack formation.
Whenever the preservation of original substance obtains priority in a restoration task, reprofiling techniques using repair mortars are a welcome solution. For ordinary concrete repair aesthetic aspects are of minor importance whereas for the restoration of natural stone elements they come to the fore. Especially for listed buildings and monuments, historico-cultural and aesthetical interests become the ruling Parameters for planning and execution of restoration tasks. Nevertheless the technical and constructive requirements have to be considered and deterioration processes have to be understood to ensure sustainability and durability of the repair task. Due o differences in the Chemical and mineralogical composition, natural stone provides a vast variety of texture and colour. Also the range of different mechanical and durability related properties is far wider than found with concrete for example. A research project dealing with the development of a modular repair mortar System for natural stone is currently set up at the BAM. To provide the conservator with the best possible options to match colour, texture and technical requirements, the System will be setup on a modular basis. Several different binder Systems on basis of cement, lime and sodium Silicate as well as polymer based Systems are planned, which can be combined with different aggregate compositions and different pigments. To evaluate the mortar performance, test procedures will be defined for tests on mortar samples and on composite specimens. In the paper the experimental Programme will be explained and first results will be presented and discussed.
Wärmebehandlung und Autoklavierung von UHPC - Neue Perspektiven für die Betonfertigteilindustrie
(2011)
Das Gefüge von UHPC ist durch eine dicht gepackte und fehlstellenarme Matrix gekennzeichnet. Eine zusätzliche Optimierung ist durch eine Wärmebehandlung bzw. hydrothermale Nachbehandlung (Autoklavierung) unter einem Wasserdampfsättigungsdruck möglich. Die Wärmebehandlung von Beton ist ein in der Betonfertigteilindustrie geläufiges Verfahren, um die Erstarrungszeit zu verkürzen und höhere Frühfestigkeiten zu erreichen.
This paper presents the results of an experimental study on the influence of polypropylene (PP) fibres on the thermal strain of high strength concrete (HSC) at temperatures up to 750°C. Concerning this topic only few results can be found in the literature and systematic investigations are missing. However, basic knowledge is necessary to understand the internal damage processes as well as for structural design.
To explain the differences in the thermal strain of HSC with and without addition of PP fibres the internal damage processes were investigated with acoustic emission (AE) analysis and ultrasound (US). Furthermore the weight loss was measured continuously during heating to monitor the drying of the specimen. This novel approach by combining these different methods with strain measurements at high temperatures allows the integral description of the internal damage processes. The results reveal significant differences in the thermal strain of HSC when PP fibres are added. Between 200°C and 250°C the thermal strain of HSC with PP fibres is superimposed by shrinkage caused by accelerated drying. Above 250°C it is lower than that of plain HSC without PP fibres. It is supposed that it is caused by a more homogeneous distribution of micro cracks whereby the fibre beds acting as defects in the concrete.
Hence this paper gives a contribution to the general understanding of the impact of PP fibres in HSC at high temperatures and points out the influence of the fibres on the thermal strain of HSC.
Sustainable evaluation - concept to assess the applicability of secondary aggregates in concrete
(2011)
Nowadays there are several applications of mineral recycling materials and residues. At present an assessment method for the use of secondary raw materials, which considers sustainability aspects, does not exist. In the framework of the German DAfStb/BMBF research project “Sustainable Building with Concrete” an assessment concept was developed. It includes the following four assessment steps: I. Basic considerations, II. Advantages for sustainable construction, III. Alternative paths for application, and IV. Sensitivity analysis. The concept was developed on the basis of recycled concrete aggregates, which are already used according to German standards.
Afterwards, it was applied and verified by the evaluation of the utilisation of municipal solid waste incinerator bottom ashes (referred to MSWI bottom ashes).
Although being a very promising area of concrete technology, computational modeling of fresh concrete flow is a comprehensive and time consuming task. The complexity and required computation time are additionally increased when simulating casting of heavily reinforced sections, where each single reinforcement bar has to be modeled. In order to improve the computation speed and to get closer to a practical tool for simulation of casting processes, an innovative approach to model reinforced sections is proposed here. The basic idea of this approach is to treat the reinforcement zone as a porous medium in which a concrete is propagating. In the present paper, the numerical implementation of this concept is described. A methodology allowing for the computation of the equivalent permeability of the steel bars network is suggested. Finally, this numerical technique efficiency is evaluated by a comparison with experimental results of model fluids casting in model formworks.
Nanotechnologie im Bauwesen
(2007)
Mikrorissbildung in Hochleistungsbeton - Vom Modell zu den Auswirkungen auf Betoneigenschaften
(2007)
Nanotechnologie im Bauwesen
(2008)
Zu den Zielen der Nanotechnologie gehört die Entwicklung, Produktion und Anwendung von Materialien und Werkstoffen mit völlig neuartigen Leistungsspektren. Für die Baupraxis und die Materialforschung lassen sich über den Einsatz der Nanotechnologie Ziele wie die Optimierung von Baustoffeigenschaften, Vermeidung von Schäden und neue Funktionalitäten definieren. Der vorliegende Beitrag gibt einen Überblick über mögliche Anwendungsbereiche der Nanotechnologie im Bausektor, wie z. B. zementgebundene Baustoffe, Außen- und Dachfassaden, Fenster und Verglasungen, Brandschutz, Inneneinrichtung und Infrastrukturbau. Zudem werden aktuelle Forschungsarbeiten mit nanowissenschaftlichem und nanotechnologischem Schwerpunkt im Bereich baustoffbezogener Materialien der Bundesanstalt für Materialforschung und -prüfung (BAM) in Berlin vorgestellt. Die Forschungstätigkeiten beziehen sich zum einen auf die Modifikation der Hydratphasen in Ultra-Hochleistungsbeton (UHPC) und zum anderen auf die Weiterentwicklung von Anti-Graffiti-Systemen.
Einsatz innovativer Verfahren der Bauwerksdiagnose für die Bestandserfassung - ausgewählte Beispiele
(2007)
This chapter provides an overview of methods that are commonly used for the analysis of the original water content of fresh and hardened concrete. The methods consist of direct methods, which detect the water content or the water/cement ratio primarily, as well as indirect methods, which measure other material characteristics related to the water content.
Computational modeling of fresh SCC flow is a comprehensive and time consuming task. The computational time is additionally increased when simulating casting of reinforced sections, where each single reinforcement bar has to be modeled. In order to deal with this issue and to decrease the computational time, an innovative approach of treating a reinforcement network as a porous medium is applied. This contribution presents the model for concrete flow through reinforced sections, based on Computational Fluid Dynamics (CFD), coupling a single-phase flow model for SCC and a continuum macroscopic model for porous medium. In the last part of this paper, numerical simulations are compared with experimental results obtained on model fluids.
Trotz der zahlreichen Möglichkeiten zur Beeinflussung der Mörteleigenschaften durch Mischungsmodifikationen ist es nahezu unmöglich, einzelne Eigenschaften unabhängig von anderen zu verändern. Bei einer Mischungsoptimierung muss im Einzelfall immer entschieden werden, welcher der gewünschten Eigenschaften die höchste Priorität zukommt.
Anhand von Parameterstudien wird im vorliegenden Artikel verdeutlicht, wie es für bestimmte Anwendungen sinnvoll sein kann, die Verschlechterung einzelner Eigenschaften zu akzeptieren, wenn dadurch eine für den speziellen Einsatzfall essenzielle Eigenschaft verbessert werden kann. Die komplexen Wechselwirkungen der einzelnen Bestandteile fuhren dazu, dass auch scheinbar widersprüchliche Kombinationen von Zusatzmitteln im Einzelfall erforderlich werden können. Zur Anpassung der meisten Mörteleigenschaften gibt es verschiedene Möglichkeiten der Zielerreichung mit jeweils unterschiedlichen Nebeneffekten. Frisch- und Festmörteleigenschaften sind dabei gleichermaßen zu beachten.
Although concrete in general is a non-combustible material, the fire resistance of concrete structures depends, to a large extent, on the mechanical material behaviour. Fire tests have shown that SCC is often susceptible to explosive spalling due to fire exposure, in a similar manner to HPC. But there are hardly any studies available that report properties of specimens at high temperatures.
Vom Baustoff zum sicheren Bauwerk: Einsatz der Schallemissionsanalyse in der Bauabteilung der BAM
(2013)
Seit 2006 wird die Schallemissionsanalyse (SEA) in der Abteilung 7 Bauwerkssicherheit der BAM genutzt, um Gefügeveränderungen in Betonen zu untersuchen. Dabei haben sich bis heute im Wesentlichen folgende vier Forschungsbereiche herauskristallisiert:
Hydratation
Während der Hydratation von Beton ist eine ausgeprägte Schallemissionsaktivität zu beobachten, anhand derer der Hydratationsverlauf nachvollzogen werden kann. Zur Aufklärung der Quellmechanismen der Schallemissionen besteht noch weiterer Forschungsbedarf. Des Weiteren kann mit Hilfe der SEA die frühe Rissbildung in Betonen, hervorgerufen durch autogenes oder plastisches Schwinden, analysiert werden.
Alkali-Kieselsäure-Reaktion (AKR)
Bei der AKR handelt es sich um eine Reaktion alkaliempfindlicher Gesteinskörnungen mit den Alkalien des Betons bzw. mit extern, z.B. durch Tausalze, zugeführten Alkalien. Dabei werden um die oder in der Gesteinskörnung quellfähige Gele gebildet, die zu einer völligen Zerstörung des Gefüges führen können. Mit der SEA können die Rissbildung detektiert und somit die Schädigungsphasen im Verlauf der AKR identifiziert werden.
Brandverhalten
Unter Brandeinwirkung platzt die Oberfläche gefügedichter Hochleistungsbetone explosionsartig ab. Um dies zu verhindern und somit den Feuerwiderstand von Bau-teilen aus Hochleistungsbeton zu erhöhen, werden dem Beton Polypropylenfasern beigemischt. Das Schmelzen der Fasern bei einer Temperaturerhöhung trägt zu einer erhöhten Mikrorissbildung bei, die einen Spannungsabbau ermöglicht. Die SEA konnte erfolgreich eingesetzt werden, um diesen Wirkmechanismus der Fasern nachzuweisen und weiter aufzuklären.
Ermüdungsverhalten
Durch die hohen zyklischen Lasten, für die Türme und Fundamente von Windkraft-anlagen ausgelegt werden müssen, gewinnen gesicherte Kenntnisse über das Ermüdungsverhalten von Betonen an Bedeutung. Mit der SEA ist es bei hochzyklischen Belastungsversuchen an Betonen möglich, den Schädigungsgrad im Verlauf der Beanspruchung zu bestimmen. Die Schallemissionsaktivität eignet sich als Kriterium, um die Versuche bei vorab definierten Schädigungsgraden zu unterbrechen und so Proben für weitergehende Untersuchungen zu gewinnen. Diese Ergebnisse sollen perspektivisch für Überwachungssysteme für Betonbauwerke unter zyklischer Beanspruchung genutzt werden.
Alkali-silica reaction (ASR) is a chemical reaction within concrete which can lead over time to cracking and spalling. Due to the complexity of the problem, it still causes damage to concrete constructions worldwide.
The publication aims to illustrate the interdisciplinary research of the German Federal Institute for Materials Research and Testing (BAM) within the last 20 years, considering all aspects of ASR topics from the macro to the micro level. First, methods for characterization and assessment of ASR risks and reaction products used at BAM are explained and classified in the international context. Subsequently the added value of the research approach by combining different, preferably nondestructive, methods across all scales is explained using specific examples from a variety of research projects. Aspects covered range from the development of new test-setups to assess aggregate reactivity, to analysis of microstructure and reaction products using microscopical, spectroscopical and X-ray methods, to the development of a testing methodology for existing concrete pavements including in-depth analysis of the visual damage indicator and the de-icing salt input using innovative testing techniques. Finally, research regarding a novel avoidance strategy that makes use of internal hydrophobization of the concrete mix is presented.
ln most of the ASR-test procedures, the expansion of concrete or mortar specimens is used as an indicator to assess the ASR-potential of an aggregate or a specific concrete mix. For these tests, the specimens are stored in an ASR-provoking environment, where the reaction is accelerated by elevated temperature and humidity. To measure the length change, the storage must be interrupted for at least a few minutes. Düring the 60 °C Concrete Prism Test (60 °C-CPT), the specimens are cooled down to 20 °C for 24 hours, to ensure the same hygrothermal conditions for every measurement. This limits the number of measurements during the test period and may lead to additional effects, that probably influence the expansion development.
With a recently developed device, it is possible to continuously monitor the expansion ofprisms without interrupting the ASR-provoking storage. Due to the dense database of this automated test, the results can contribute to a better understanding of the ASR-process. This study compares results of the automated and conventional 60 °C-CPT. Tests of different aggregates showed, that the results of the automated and conventional test are consistent, but the expansions during the conventional test are generally higher. Preliminary results led to the conclusion, that the cooling for the measurements leads to additional expansions. Therefore, a modified threshold should be discussed for the automated 60 °C-CPT.
Baustoffe im Betonbau
(2019)
In dem Kap. „Baustoffe im Betonbau“ werden zunächst die Baustoffe vorgestellt, die für die Herstellung von Stahlbeton- und Spannbetonbauwerken erforderlich sind (im Wesentlichen Beton, Betonstahl und Spannstahl). Herstellungsbedingte, typische Eigenschaftsprofile der Baustoffe werden aufgezeigt und ein Bezug zu entsprechenden Anwendungsgebieten hergestellt.
If the amount of sulfate within the mix design for concrete is not balanced, ettringite formation which first controls solidification continues while the concrete is hardening. Ettringite forms by reaction of sulfate contained in the cement or in some admixture with calcium aluminate (C3A) as cement component. The “late primary ettringite formation” promotes an increase in volume within the hardened concrete leading to cracks. To analyze the effect of substituting part of ordinary Portland cement (OPC) by a treated brown coal fly ash mortar bars were tested according to ASTM C452. This test method was originally developed to extrapolate from the internal to external sulfate attack and is based on the idea that by testing a concrete mixture containing sulfate the process of deterioration is accelerated because it does not have to diffuse into the concrete before reaction first. In addition to the samples prescribed in ASTM C452 further samples in the size of the German SVA procedure were tested also designed for accessing the external sulfate resistance. The results show that while the replacement of 25 % of cement by brown coal fly ash leads to length changes around the limit defined by ASTM, the substitution of 50 % cement exceeded the limit by a multiple. The progress of expansion is the very similar for the two geometries tested. In-situ XRD measurements confirmed that while for pastes made of OPC the formation of ettringite is completed after 20 hours, this is not true for the mixtures containing the brown coal fly ash.
In a different study the effect of hydrothermal treatment on the phase composition of ultra-high-performance concrete was analyzed. The results show that the sulfate and aluminate resulting from the decomposition of ettringite are bound into new phases.
If this binding is permanent this might allow the larger use of sulfate bearing raw materials.
Basic oxygen furnace slags (BOFS) are by-products of the steelmaking process. Several researchers have studied the production of Portland cement clinker and metallic iron from BOFS via a reductive treatment.
In this study, we applied a carbothermal reduction of BOFS in a technical-scale electric arc furnace and characterised the clinker-like products. Those clinker-like non-metallic products (NMPs) had a chemical and mineralogical composition comparable to clinker for ordinary Portland cement (OPC) and contained large elongated alite crystals as major component. The pure NMPs reacted more slowly and achieved a lower degree of hydration compared with commercial OPC.
If the reactivity of the products can be further increased by employing specific adaptations, it can be used as a full clinker substitute for OPC. Nevertheless, it is also an option to use the material without further modifications as a cement component or concrete addition, which contributes to the strength development in both cases.
Um den Abbau primärer Rohstoffe zu reduzieren, wurden deponierte oder niederwertig eingesetzte industrielle Reststoffe hinsichtlich einer höherwertigen Verwendung im Betonbau untersucht. Zur Bewertung des Einsatzpotentials als Zementbestandteil oder Betonzusatzstoff erfolgte zunächst eine chemisch-mineralogische und betontechnologische Charakterisierung der Materialien. Reststoffe, die die normativen Anforderungen hinsichtlich der Zementzusammensetzung erfüllen, wurden anschließend zu verschiedenen Anteilen als Zementsubstitut in Mörtel eingesetzt. In vergleichenden Untersuchungen erfolgte die Ermittlung der Frisch- und Festmörteleigenschaften.
Kalorimetrische Untersuchungen sollten die Auswirkungen der Reststoffe auf die Zementhydratation zeigen. Ausgewählte Untersuchungsergebnisse an Reststoffen aus der Industrieabwasseraufbereitung, dem Altpapierrecycling, der Biomasseverbrennung und der Metallurgie werden vorgestellt.
In recent years the German motorway network has seen an increase in the occurrence of damage to concrete road surfaces which can be attributed to the alkali-silica reaction (ASR). In view of the often drastically reduced life expectancy of road surfaces due to ASR, research activity in this field has notably increased. Alongside preventative measures in concrete technology, the main research focus up to now has been the development of performance-oriented testing procedures for ASR prevention. This included more specifically the accelerated simulation of climatic effects and external alkali penetration on road surfaces. The effects of mechanical pre-damage resulting from cyclic traffic loading and climatic impact had previously not been taken into consideration. Since 2011, the five-partner research group 1498 sponsored by the German Research Foundation (DFG) has been pursuing research on how simultaneous cyclic loading and external alkali penetration impacts destructive ASR in road surface concretes. The depiction of the myriad degradation and transport processes necessary for an understanding of these effects requires close interaction between experiments and their multi-scale modelling. This paper aims to focus on the aforementioned experiments by means of innovative testing techniques. The research is founded on a series of cyclic fatigue tests performed on large-format beams, both with and without previous application of a sodium chloride (NaCl) solution, with simultaneous tracking of crack development. Subsequently, smaller test specimens were extracted from the pre-damaged beams for further experiments. These included the spatial visualization and quantification of fatigue-induced cracks using micro X-ray 3D-computed tomography (3D-CT). Additionally, the effects of fatigue-induced cracks on alkali transport were investigated using Laser-Induced Breakdown Spectroscopy (LIBS). Subsequent storage of the small-format test specimens, with and without cyclic pre-damage, in an ASR-conducive environment then provided initial findings on the influence of fatigue-induced predamage on the ASR.
The susceptibility of different aggregate types used in concrete to ASR is strongly associated with their petrography. The aim of this study is to assess the influence of the aggregate size on the ASR potential, in particular applied to the sand fractions in the size range of 0.125-4 mm. The investigation concept is based on the hypothesis that at a specific particle size reactive aggregates could change their characteristic influence in mitigating ASR instead of promoting it. For the study of the size dependent behaviour mortars are prepared, considering aggregates of different reactivity, including very reactive, slow-late and quasi non-reactive types. The analysis is based on a stepwise substitution concept, in which mortars with a constant overall grain size distribution are compared, while only one size fraction of the non-reactive base aggregate is substituted by a reactive aggregate type of this specific size fraction. For the expansion experiments an accelerated mortar bar test (80°C, immersed in NaOH solution) was applied. The results show that the slow-late reactive greywacke yielded a strong reduction of the expansion below an aggregate size in the range of 0.5-1 mm. On the other side with the very reactive borosilicate glass, the expansions increased steadily with decreasing size. To validate if the acquired expansions were caused by ASR, thin sections were analysed. Mainly, higher expansion values were consistent with extensively more amounts of ASR indicators.
Thermal treatment improves the excellent properties of UHPC. Recent studies have shown that an increase in compressive strength of more than 30 % is possible. However, the accurate conditions of thermal treatment for a maximal strength are considered as yet undetermined. A multitude of parameters can be varied: temperature, pressure, water saturation, and duration of the process steps. These parameters influence the phase development and in consequence the macroscopic properties of UHPC. The primary objective of the presented study was the optimisation of the conditions for thermal treatment, concerning compressive strength. It focuses on pre-storage time and duration of the treatment at defined temperatures and pressures (90 °C and 185 °C/1.1MPa).
As expected, experimental results showed a fundamental change of phase composition in hydrothermally treated UHPC in comparison to standard cured UHPC: Ettringite decomposes at higher temperatures and is absent after thermal treatment; the amount of portlandite and clinker phases decreases. The change of phase composition is accompanied by increased compressive strength.
Experimental studies of calcium-silicate-systems at hydrothermal conditions predict the formation of the crystalline C-S-H phase tobermorite. In fact, this is a typical phase occurring in other hydrothermally treated calcium-silicate-systems like Autoclaved Aerated Concrete (AAC). Commonly, high strength is attributed to the presence of tobermorite; however, in the presented study tobermorite was not detected in the hydrothermally treated UHPC. Therefore, tobermorite cannot be responsible for the increased strength of hydrothermally treated UHPC.
In conclusion the development of phases and strength of UHPC at hydrothermal conditions differs fundamentally from AAC and the experimental studies with water saturation. Results of these systems cannot be transferred to UHPC. In thermally treated UHPC, the hydration of clinker is enhanced and the puzzolanic reaction is intensified. Hence, more C-S-H is formed that fills pores and cracks, leading to a denser structure and finally to higher strength.
Though, concrete in general is a non-combustible building material, modern High Performance Concrete (HPC) is very susceptible to violent explosive spalling during a fire attack. This requires protective measures for fire safety design of concrete structures. The current most worthwhile method to prevent explosive spalling is the addition of monofilament Polypropylene fibres (PP-fibres). However, since it has become common knowledge that PP-fibres are suitable for fire safety design, a variety of theories concerning the mode of action of PP-fibres have been suggested. The present article summarizes the most important hypothesis and presents an innovative method for the analysis of micro structural processes in heated specimens. The results show that due to the thermal decomposition of PP-fibres capillary channels are created. Simultaneously, a netlike micro crack formation occurs, which connects these capillary channels. This enables the relief of internal stresses (mechanical effect) and the formation of a permeable transport system for the escaping water vapour (permeation effect).
High resolution synchrotron X-ray diffraction (SyXRD) was applied for a microstructural profile analysis of concrete deterioration after sulfate attack. The cement matrices consist of ordinary Portland cement and different amounts of supplementary cementitious materials, such as fly ash, natural pozzolana and granulated blast furnace slag. The changes of the phase composition were determined along the direction of sulfate ingress. This approach allows the identification of reaction fronts and zones of different phase compositions and conclusions about the mechanisms of sulfate attack. Two reaction fronts were localized in the initial 4 mm from the sample surface. The mechanism of deterioration caused by the exposition in the sulfate-bearing soil is discussed. SyXRD is shown to be a reliable method for investigation of cementitious materials with aggregates embedded in natural environments.
In diesem Beitrag werden Untersuchungsergebnisse vorgestellt, die den Einfluss von Mikrosilica auf die Selbstaustrocknung und das damit verbundene autogene Schwinden der Bindemittelmatrix von Hochleistungsbetonen beschreiben. Die dadurch hervorgerufenen Schädigungsprozesse wurden mit Hilfe von zerstörungsfreien Prüfmethoden verfolgt. Dabei zeigte sich, dass eine durch äußeren Zwang bedingte Mikrorissbildung durch Schallemissionsanalyse detektiert werden kann.