Filtern
Erscheinungsjahr
- 2021 (5) (entfernen)
Dokumenttyp
- Zeitschriftenartikel (3)
- Vortrag (1)
- Posterpräsentation (1)
Sprache
- Englisch (5)
Schlagworte
- Cement (5) (entfernen)
Organisationseinheit der BAM
- 1 Analytische Chemie; Referenzmaterialien (3)
- 1.1 Anorganische Spurenanalytik (2)
- 7 Bauwerkssicherheit (2)
- 1.2 Biophotonik (1)
- 5 Werkstofftechnik (1)
- 5.1 Mikrostruktur Design und Degradation (1)
- 7.0 Abteilungsleitung und andere (1)
- 7.4 Baustofftechnologie (1)
- 7.6 Korrosion und Korrosionsschutz (1)
- 8 Zerstörungsfreie Prüfung (1)
Eingeladener Vortrag
- nein (1)
The increasingly sophisticated nature of modern, more environmentally friendly cementitious binders requires a better understanding and control particularly of the complex, dynamic processes involved in the early phase of cement hydration. In-situ monitoring of properties of a constantly changing system over a defined period of time calls for simple, sensitive, fast, and preferably also non-invasive methods like optical spectroscopy
In civil engineering, clear regulations and standards, such as the European standard DIN EN 206 apply to ensure that the existing infrastructure is sufficiently resistant to a wide range of exposure conditions. Despite these regulations, in practice concrete structures often show severe damage during their service life. One of these damages is pitting corrosion of the reinforcement, which can be caused by chloride ingress into the structure. Therefore, determining the distribution and depth of chloride ingress is important in predicting the service life. LIBS provides an alternative method to conventional wet chemistry in civil engineering. Despite many advantages, the use of LIBS has been severely limited due to a lack of regulations. Together with project partners from research and industry, we are currently working on a leaflet that will regulate chloride analysis in civil engineering using LIBS. This year, an international round robin test was organized to evaluate the performance of LIBS for chloride analysis in cement pastes. No specifications were given for the experimental LIBS setup and data evaluation. The preliminary results are presented.
With the aim of identifying the origin and the manufacturer of a cement, a reliable procedure that provides unambiguous results is needed. Such procedure could resolve practical issues in damage research, liability issues and forensic investigations. A substantial number of attempts for fingerprinting of building materials, including cement, has already been carried out during the last decades. Most of them were based on concentration analysis of the main elements/components. This review provides an overview of provenance studies of cement and the main approaches commonly used. Provenance studies of cement via isotope techniques are also presented and discussed as representatives of the state-of-the-art in the field. Due to the characteristic properties and the occurrence of carefully selected isotope ratios, unique fingerprints of different kinds of materials can be provided by these methods. This property has largely been explored in various scientific fields such as geo- and cosmochemistry, food forensics, archaeology, geochronology, biomedical studies, and climate change processes. However, the potential of isotope techniques in cement and concrete research for provenance studies has barely been investigated.
Therefore, the review outlines a suitable approach using isotope ratios, which could lead to reliable provenancing of cementitious materials in the future.
The presentations gives a short introduction into isotope analysis illustrated by examples from archaeology, food provenancing and metrology. In the main part current projects on the provenance determination of cement, the intercalibration of Mg isotope reference materials and the development of a new calibration approach for isotope measurements are presented.
For reliability and safety issues of injection wells, corrosion resistance of materials used needs to be determined. Herein, representative low-cost materials, including carbon steel X70/1.8977 and low alloyed steel 1.7225, were embedded in mortar to mimic the realistic casing-mortar interface. Two types of cement were investigated: (1) Dyckerhoff Variodur commercial Portland cement, representing a highly acidic resistant cement and (2) Wollastonite, which can react with CO2 and become stable under a CO2 stream due to the carbonation process. Exposure tests were performed under 10 MPa and at 333 K in artificial aquifer fluid for up to 20 weeks, revealing crevice corrosion and uniform corrosion instead of expected pitting corrosion. To clarify the role of cement, simulated pore water was made by dispersing cement powder in aquifer fluid and used as a solution to expose steels. Surface analysis, accompanied by element mapping on exposed specimens and their crosssections, was carried out to trace the chloride intrusion and corrosion process that followed.