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)
Fused cement clinker can be produced from molten basic oxygen furnace slag (BOFS) by way of a reductive thermochemical treatment. During the thermochemical treatment, oxidic iron is reduced to metallic iron and separated. The resulting low-iron slag has a chemical and mineralogical composition similar to ordinary Portland cement (OPC) clinker. In this study, the hydraulic reactivity of the fused clinker from BOFS with and without gypsum was investigated using isothermal calorimetry, differential scanning calorimetry, in situ X-ray diffraction and powder X-ray diffraction. Furthermore, a synthetic fused clinker without foreign ions and fused clinker produced by a mixture of both materials was studied. The hydraulic reaction of the fused clinker from BOFS was considerably slower than that of OPC. However, the reaction can be accelerated by adding gypsum as a sulfate carrier. Furthermore, the results showed an increased reaction rate with decreasing content of foreign ions such as Fe, P or Mn.
Materials that support natural biodiversity on their surfaces can compensate for human activities that have a negative impact on nature and thus contribute to a carbon-neutral and nature-positive world. Specifically designing bioreceptive materials which favor the growth of biofilms on their surface is an approach complementing conventional, macroscopic green façades. But what exactly characterizes a bioreceptive substrate and how do biofilm and substrate interact? How and why does a spontaneous colonization and the formation of biofilms take place? What are biofilms and how can they be established in a laboratory setting? How can this existing knowledge be transferred to the artificial stone concrete so that this material can be tuned to increase (or decrease) its bioreceptivity?
This review paper aims at summarizing the existing state of knowledge on bioreceptive concrete and pointing out inconsistencies and contradictions which can only be removed by more interdisciplinary research in the field.
Even after autoclaving for 2 weeks in the temperature range of 120 to 200 °C, CEM I paste with a water-to-cement ratio of 0.5 still contains some low-crystalline C-S-H. The conversion of low-crystalline C-S-H to crystalline is faster with increasing temperature. The observed low-crystalline and crystalline C-S-H phases (reinhardbraunsite, jaffeite) indicate that the sampleshave not reached equilibrium yet under these experimental conditions. However, there is a good agreement between experiment and thermodynamic modelling for the other solids indicating that the used datasets are suitable for this application.
Die sprunghaft zunehmende Wichtigkeit von FAIR- und Open-Data für die Qualitätssicherung, aber auch für die Nachnutzbarkeit von Daten und den Erkenntnisfortschritt führt zu enormem Flandlungsbedarf in Forschung und Entwicklung. Damit verbunden laufen derzeit vielfältige, ambitionierte Aktionen, z. B. bezüglich der Erstellung von Ontologien und Wissensgraphen. Das Knowhow entwickelt sich rasant, die Ansätze zur Implementation entstehen in verschiedenen Fachwelten bzw. mit
unterschiedlichen Zielsetzungen parallel, so dass recht heterogene Herangehensweisen resultieren.
Diese Veröffentlichung fokussiert auf Arbeiten, die derzeit als möglichst ganzheitlicher Ansatz für Materialdaten im Rahmen der Digitalisierungsinitiative „Plattform MaterialDigital" vorangetrieben werden. Die Autoren bearbeiten baustoffbezogene Aspekte im Verbundprojekt „LeBeDigital - Lebenszyklus von Beton". Zielsetzung ist die digitale Beschreibung des Materialverhaltens von Beton über den kompletten Herstellungsprozess eines Fertigteils mit einer Integration von Daten und Modellen innerhalb eines Workflows zur probabilistischen Material- und Prozessoptimierung.
Es wird über die Vorgehensweise und die dabei gewonnenen Erfahrungen berichtet, nicht ohne den Blick auf die oft unterschätzte Komplexität der Thematik zu lenken.
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.
The adaption of the set-up for gas permeability measurements for ultra-high performance concrete
(2022)
In the framework of this project, a steam pressure vessel was to be developed from ultra-high perfor-mance concrete (UHPC) to withstand process temperatures of 200 °C and the respective steam pressure of 15,5 bar. To guarantee the long-term water vapour tightness of the system, the permeability of two UHPC mixtures were tested after long-term cyclic autoclaving. As UPHC shows a high density and therefore low permeability, measurements after the RILEM-Recommendation (TC 116-PCD) reached their detection limit. Therefore, the measurement set-up was adapted to measure the permeability of highly dense UHPC more reliably and quickly. This adaption includes measurements in a higher pres-sure range, the change of sample size thickness and the usage of Ar as a medium compared with the RILEM Recommendation. Additionally, the system was equipped with two pressure sensors and Ar-flowmeters to guarantee a continuous record of the experimental parameters. The new system was tested and evaluated by comparing measurements with the RILEM recommended system. Preliminary results show that the adapted system is capable to provide efficient and reliable results of concrete with low permeability.
Beton ist weltweit einer der wichtigsten Konstruktionswerkstoffe und zeichnet sich durch eine enorme Anpassungsfähigkeit an sich verändernde Anforderungen aus. Damit verbunden ist eine hohe und kontinuierlich zunehmende Komplexität hinsichtlich der Ausgangsstoffe, Rezepturen und des Herstellungsprozesses. Folglich setzt eine Ausschöpfung des technischen und umweltbezogenen Potenzials der Betonbauweise höchste Expertise bei den Einzelakteuren der Bauindustrie voraus.
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.
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.