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)
Since its invention in the early 1990’s, self-consolidating concrete has never become well established in the ready-mix sectors worldwide. The reason for this can be mainly found in the fact that the sophisticated compositions are sensitive against changing environments. This lack of robustness can be attributed to the interaction between cement hydration reaction and high range water reducing agent (HRWRA). Understanding the relevant mechanisms that control the initial flow performance as well as the flow retention helps optimizing SCC mixtures that perform either steadily in one specific environment or that perform largely similarly at steadily changing environments.
This paper depicts how HRWRAs interact with clinker and hydration phases and discusses the important role of the charge density of a polycarboxylic HRWRA in the way the rheology is affected. Based on rheometric results and observations of the Vicat setting times, it is shown that increasing charge densities of the HRWRA and decreasing water to powder ratios (w/p) reduce the flow retention and have lesser retarding effect on the setting. Based on the discussion, optimization procedures for the mixture composition and the HRWRA modification are suggested to achieve optimized performance for varying environmental situations or highest robustness for specific conditions.
ln order to observe the influence of stabilising agents (STA) based on starch and diutan gum, rheometric experiments and setting tests were conducted on cement pastes with and without PCE superpiasticizers. The results show that with regard to yield stress both STAs show differing behaviours in Systems without PCE. In presence of PCE, yield stress infiuences of the STAs retreat into the background. The Vicat results exhibit that STAs can reduce the retard ing effect of PCE.
Todays superplasticizers for self-compacting concrete and high Performance cementitious materials are very versatile. Typically superplasticizers are composed of a polycarboxylic backbone equipped with polyethylene oxide graft chains of variable length and grafting degree. The mode of operation of these admixtures is based on the steric repulsion of the particles upon adsorption. The adsorption is strongly depending upon the charge density of a superplasticizer and the time dependent Adsorption processes control the retention of the flow performance – an important issue particularly for ready-mix and construction site concrete. However, the properties of polycarboxylic superplasticizers typically remain a black box for users. The paper suggests a simple and rapid test method, which can be conducted without sophisticated equipment, to qualitatively distinguish between two types of superplasticizers based on the adsorption mechanism. Interpreting the results in the right way provides a powerful tool to choose the right admixture for individual time dependent flow specifications.
Innovative admixture technology has significantly widened up the ränge of possibilities of concrete engineers. For many decades the water to cement ratio (w/c) was the major influencing factor for the performance of concrete. Due to the need to adjust a consistency, which still allowed reasonable workability, the w/c was typically significantly higher than technologically reasonable. Rheology modifying admixtures Support adjusting the concrete consistency largely independent of the w/c. It was only after the invention of the first superplasticizers that modern concrete technology significantly evolved in terms of flowability, strength, and durability, and only due to the steady evolution of the technology modern innovations, such as Self-Compacting Concrete, Ultra-High-Performance Concrete, or Engineered Cementitious Composites were made possible. Today’s superplasticizers are extremely versatile and can be adjusted to individual technological specifications. However, the other side of the coin of versatility is that cementitious Systems incorporating superplasticizers have become more sensitive against environmental influences, such as the environmental temperature, which may cause unwanted effects or demand for supplementary admixture use such as stabilizing admixtures. Hence, concrete mixture composition with admixtures demands for a high level of expertise and offen there is lack of awareness about the mode of Operation of rheology modifying admixtures among concrete technologists. The paper gives a comprehensive overview about rheology modifying admixtures such as superplasticizers or stabilizing agents, and how they can be used depending upon the application in the most favourable way. Based on experiences with the sub-Saharan African concreting boundary conditions, which exhibit many challenges in terms of environmental boundary conditions and construction site logistics, conclusions are finally drawn, how admixtures can be used in the most beneficial way to improve the concrete casting Situation.
The fresh behaviour of self-compacting concrete (SCC) at varying temperatures differs from that of normal vibrated concrete. This is because the rheology of SCC depends not only on degree of cement hydration, but also on the adsorption of superplasticizers – mostly polycarboxylate based polymers (PCE) -, which is affected by the time and hydration progress. Due to the variety of PCEs and mixture compositions for SCC a prediction of the rheology at varying temperatures is complicated. The charge densities of PCEs as well as the water to solid ratio in the paste are identified to be the main decisive parameters for robust fresh concrete properties.
Rheometric concrete investigations with different SCC mixture compositions and varied anionic charge densities of the PCE were conducted. SCC which is rich in powder components showed robust performance at low temperatures while SCC with low powder content was favourable at high temperatures. High charge density PCE pointed out to be very robust at low temperatures but at high temperatures it significantly reduced the flow retention. Low charge density PCE could not generate self-compacting properties at low temperatures but retained the flow performance over sufficiently long time. Based on considerations about particle interactions and adsorption mechanisms of PCEs, the relevant processes are explained and options for the development of robust mixture compositions for individual temperature ranges are itemised.
To design robust self-consolidating concrete (SCC) for various environmental conditions, it is essential to understand the relevant mechanisms that control the flow performance. This paper depicts how high range water reducing agents (HRWRAs) interact with clinker and hydration phases, and it discusses the important role of the charge density of polycarboxylic HRWRAs in the way the rheology is affected. Based on the rheometric investigations on SCC mixture compositions with different water to powder ratios (w/p) and observations of their pastes' Vicat setting times, the study shows that increasing charge densities of the HRWRA and decreasing w/p reduce the flow retention and have lesser retarding effect on the setting. Based on the test results and discussions optimization procedures for the mixture composition and the HRWRA modification are suggested to achieve optimized performance for varying environmental situations and highest robustness for specific conditions.
Polysaccharides provide high potential to be used as rheology modifying admixtures in mineral binder systems for the construction industry such as concrete or mortar. Since superplasticizers have become state of technology, today, concrete is more and more adjusted to flowable consistencies. This often goes along with the risk of segregation, which can be effectively avoided by adding stabilising agents supplementary to superplasticizers. Stabilising agents are typically based on polysaccharides such as cellulose, sphingan gum, or starch. Starch clearly distinguishes in its effect on rheology from other polysaccharides, mainly due to the strong influence of amylopectin on the dispersion and stabilisation of particles. Based on rheometric investigations on cementitious and limestone based dispersions with different volumetric water to solid ratios, the mode of operation of modified potato starch is explained in comparison to a sphingan gum. It is shown that the stabilising effect of starch in a coarsely dispersed system is mainly depending upon the water to solid ratio and that above a certain particle volume threshold starch mainly affects the dynamic yield stress of dispersions, while plastic viscosity is affected only to a minor degree. Sphingans operate more independent of the particle volume in a coarsely dispersed system and show significantly higher effect on the plastic viscosity than on the yield stress. In systems incorporating superplasticizers, influences of both stabilising agents on yield stress retreat into the background, while both observed polysaccharides maintain their effect on the plastic viscosity.
Innovative admixture technology has significantly widened up the ränge of possibilities of concrete engineers. For many decades the water to cement ratio (w/c) was the major influencing factor for the performance of concrete. Due to the need to adjust a consistency, which still allowed reasonable workability, the w/c was typically significantly higher than technologically reasonable. Rheology modifying admixtures Support adjusting the concrete consistency largely independent of the w/c. It was only after the invention of the first superplasticizers that modern concrete technology significantly evolved in terms of flowability, strength, and durability, and only due to the steady evolution of the technology modern innovations, such as Self-Compacting Concrete, Ultra-High-Performance Concrete, or Engineered Cementitious Composites were made possible. Today’s superplasticizers are extremely versatile and can be adjusted to individual technologicalspecifications. However, the other side of the coin of versatility is that cementitious Systems incorporating superplasticizers have become more sensitive against environmental influences, such as the environmental temperature, which may cause unwanted effects or demand for supplementary admixture use such as stabilizing admixtures. Hence, concrete mixture composition with admixtures demands for a high level of expertise and offen there is lack of awareness about the mode of Operation of rheology modifying admixtures among concrete technologists. The paper gives a comprehensive overview about rheology modifying admixtures such as superplasticizers or stabilizing agents, and how they can be used depending upon the application in the most favourable way. Based on experiences with the sub-Saharan African concreting boundary conditions, which exhibit many challenges in terms of environmental boundary conditions and construction site logistics, conclusions are finally drawn, how admixtures can be used in the most beneficial way to improve the concrete casting Situation.
Pathway of a damaging mechanism - Analyzing chloride attack by synchrotron based X-ray diffraction
(2015)
Typically, the changes of the phase compositions due to the chemical attack are studied in-situ only by chemical analysis or microscopy. In this study, the chloride transport and binding in the cement matrix in different cementitious materials was analyzed by synchrotron based X-ray diffraction (SyXRD) and energy dispersive X-ray spectroscopy (EDX). Sample materials consisting of cement paste were embedded in high concentrated sodium chloride solution over different time spans. Afterwards, the phase and chemical compositions were determined. The high spatial resolution and the information about the chloride distribution offer a detailed view of chloride binding in the cement matrix and allow the conclusions about the degradation mechanisms. The results are discussed related to the influence of different supplementary cementitious materials on the damaging mechanism.