TY  - JOUR
A1  - Kleiner, Florian
A1  - Rößler, Christiane
A1  - Vogt, Franziska
A1  - Osburg, Andrea
A1  - Ludwig, Horst-Michael
T1  - Reconstruction of calcium silicate hydrates using multiple 2D and 3D imaging techniques: Light microscopy, μ-CT, SEM, FIB-nT combined with EDX
JF  - Journal of Microscopy
N2  - This study demonstrates the application and combination of multiple imaging techniques [light microscopy, micro-X-ray computer tomography (μ-CT), scanning electron microscopy (SEM) and focussed ion beam – nano-tomography (FIB-nT)] to the analysis of the microstructure of hydrated alite across multiple scales. However, by comparing findings with mercury intrusion porosimetry (MIP), it becomes obvious that the imaged 3D volumes and 2D images do not sufficiently overlap at certain scales to allow a continuous quantification of the pore size distribution (PSD). This can be overcome by improving the resolution and increasing the measured volume. Furthermore, results show that the fibrous morphology of calcium-silicate-hydrates (C-S-H) phases is preserved during FIB-nT. This is a requirement for characterisation of nano-scale porosity. Finally, it was proven that the combination of FIB-nT with energy-dispersive X-ray spectroscopy (EDX) data facilitates the phase segmentation of a 11 × 11 × 7.7 μm3 volume of hydrated alite.
KW  - Zementklinker
KW  - Bildsegmentierung
KW  - Rasterelektronenmikroskopie
KW  - Computertomographie
KW  - tomography
KW  - focussed ion beam
KW  - cement microstructure
KW  - micro-CT
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220106-45458
UR  - https://onlinelibrary.wiley.com/doi/10.1111/jmi.13081
VL  - 2021
SP  - 1
EP  - 6
PB  - John Wiley & Sons Ltd
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Cappachione, Clotilde
A1  - Partschefeld, Stephan
A1  - Osburg, Andrea
A1  - Gliubizzi, Rocco
A1  - Gaeta, Carmine
T1  - Modified Carboxymethylcellulose-Based Scaffolds as New Potential Ecofriendly Superplasticizers with a Retardant Effect for Mortar: From the Synthesis to the Application
JF  - Materials
N2  - This article is focused on the research and development of new cellulose ether derivatives as innovative superplasticizers for mortar systems. Several synthetic strategies have been pursued to obtain new compounds to study their properties on cementitious systems as new bio-based additives. The new water-soluble admixtures were synthesized using a complex carboxymethylcellulose-based backbone that was first hydrolyzed and then sulfo-ethylated in the presence of sodium vinyl sulphonate. Starting with a complex biopolymer that is widely known as a thickening agent was very challenging. Only by varying the hydrolysis times and temperatures of the reactions was achieved the aimed goal. The obtained derivatives showed different molecular weight (Mw) and anionic charges on their backbones. An improvement in shear stress and dynamic viscosity values of CEM II 42.5R cement was observed with the samples obtained with a longer time of higher temperature hydrolysis and sulfo-ethylation. Investigations into the chemical nature of the pore solution, calorimetric studies and adsorption experiments clearly showed the ability of carboxymethyl cellulose superplasticizer (CMC SP) to interact with cement grains and influence hydration processes within a 48-h time window, causing a delay in hydration reactions in the samples. The fluidity of the cementitious matrices was ascertained through slump test and preliminary studies of mechanical and flexural strength of the hardened mortar formulated with the new ecological additives yielded values in terms of mechanical properties. Finally, the computed tomography (CT) images completed the investigation of the pore network structure of hardened specimens, highlighting their promising structure porosity.
KW  - Mörtel
KW  - Verflüssigung
KW  - superplasticizers
KW  - carboxymethylcellulose
KW  - mortar
KW  - OA-Publikationsfonds2021
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20210804-44689
UR  - https://www.mdpi.com/1996-1944/14/13/3569
VL  - 2021
IS  - volume 14, issue 13, article 3569
SP  - 1
EP  - 17
PB  - MDPI
CY  - Basel
ER  -