A5040386978- Concrete and Cement Materials Research
- Innovative concrete reinforcement materials
- Magnesium Oxide Properties and Applications
- Concrete Properties and Behavior
- Innovations in Concrete and Construction Materials
- Clay minerals and soil interactions
- Drilling and Well Engineering
- Chemical Synthesis and Characterization
- Hydraulic Fracturing and Reservoir Analysis
- CO2 Sequestration and Geologic Interactions
- Media Studies and Communication
- Bauxite Residue and Utilization
- Groundwater flow and contamination studies
- Recycled Aggregate Concrete Performance
- Masonry and Concrete Structural Analysis
- Concrete Corrosion and Durability
- Building materials and conservation
- Calcium Carbonate Crystallization and Inhibition
- X-ray Diffraction in Crystallography
- Structural Behavior of Reinforced Concrete
- Infrastructure Maintenance and Monitoring
- Grouting, Rheology, and Soil Mechanics
- Dam Engineering and Safety
- Sociology and Education Studies
- Advanced ceramic materials synthesis
Friedrich-Alexander-Universität Erlangen-Nürnberg
2011-2023
Landesamt für Umwelt, Naturschutz und Geologie
2023
Forschungsinstitut für Anwendungsorientierte Wissensverarbeitung
2023
University of Cologne
2021
Stellenbosch University
2020
California Polytechnic State University
2008-2015
American Society of Civil Engineers
2001
Tufts University
1997-2001
RWTH Aachen University
1997-1999
Northwestern University
1996-1997
The concept of localization during the postpeak compressive strain softening is presented. To explore in compression, a feedback-control method using linear combination displacement and force that partially subtracts elastic response specimen to give stable feedback signal used. Results are presented from two test series (45 90 MPa) use this cylinders with length-to-diameter ratios ranging 2.0 5.5 It shown compression failure fact localized phenomenon. fracture energy divided into dissipated...
A suitable external standard method which was first described by O’Connor and Raven (1988) (“Application of the Rietveld refinement procedure in assaying powdered mixtures,” Powder Diffr. 3, 2–6) used to determine quantitative phase composition a commonly Ordinary Portland Cement (OPC). The also applied order amorphous contents OPC. Also investigated were impact atomic displacement parameters microstrain on calculated content. investigations yielded evidence that said do indeed exert an...
In order to gain a deeper understanding of the rheological development hydrating ordinary Portland cement (OPC) pastes at initial state, and better understand their underlying processes, quantitative X-ray diffraction (XRD) analysis measurements were conducted results combined. The time-dependent relation between phase flow behavior paste was investigated two different temperatures (20 30 °C), over period hours. Regarding during hydration, ettringite precipitation identified as dominant...
The purpose of this study was to investigate for how long the thermal power hydration can be measured with isothermal calorimetry, which is a general measurement technique stable properties that, in many cases, detect low rates processes. Measurements were conducted 365 days on cement paste Portland cement, fly ash blended and different water-to-binder ratios. results showed that all tested systems still produced measureable signal after one year. samples also analyzed by XRD days, phase...
A thorough characterization of base materials is the prerequisite for further research. In this paper, data reference (CEM I 42.5 R, limestone powder, calcined clay and a mixture these three components) used in second funding phase priority program 2005 German Research Foundation (DFG SPP 2005) are presented under aspects chemical mineralogical composition as well physical properties. The were collected based on tests performed by up to eleven research groups involved cooperative program.
The structure and solubility of hydrothermally prepared 11 Å Al-tobermorite with Al/(Al + Si) = 0.1 has been studied. NMR FTIR data indicated the formation a cross-linked, well crystalline preferential uptake Al in branching sites silicate chains. incorporation tobermorite increased basal spacing by ~0.18 Å. Solubility experiments little effect temperature on weak stabilization regard to tobermorite. experimental confirmed strong similarity structure, Al-uptake, poorly ordered C-A-S-H gel,...
This paper deals with the decisive mechanisms of thixotropic structural build-up in superplasticized cement-based suspensions related to PCE molecular structure. We investigate effect side chain length and anionic charge ratio tailored superplasticizers on under quantitative consideration colloidal contact interactions as well very early hydration kinetics. The cement pastes systematically varying structure was investigated at constant workability, i.e. dynamic yield stress, by adjusting...
Recently, a hydrous carbonate-containing brucite (HCB) with an approximate composition of MgCO3·35 Mg(OH)2·H2O was postulated as hydration product binders based on mixtures reactive magnesia and hydromagnesite (Mg5(CO3)4(OH)2·4H2O). X-ray diffraction showed that the 001 reflection this phase split into two reflections at 20 °C, whereas 60 °C only one occurred. Rietveld refinement revealed pattern HCB-phase could be fitted well when random displacement (stacking faults) movement layers in x,...
The classical external-standard method derived from the work of O'Connor & Raven [ Powder Diffr. (1988), 3 , 2–6] was used to examine hydration major phase, alite, ordinary Portland cements at different temperatures and water/alite ratios. In order estimate accuracy method, heat-flow curves were calculated alite dissolution obtained X-ray diffraction in situ experiments. this way compared with recorded using a calorimeter. It is shown that agree well
The rheological behavior of cement paste and the improvement its flowability takes center stage in many research projects. An improved can be achieved by addition superplasticizers (SP), such as polycarboxylate ethers (PCE). In order to able use these PCEs effectively a variety ways make them resistant changes environment, it is crucial understand influence SPs on hydration. For that reason, topic this paper was incompatibility specific SP an ordinary Portland (OPC). incompatible analyzed...