@article{KuglerAumuellerKrcmaretal.2022, author = {Kugler, Felix and Aum{\"u}ller, Jessica and Krcmar, Wolfgang and Teipel, Ulrich}, title = {Construction and Demolition Residuals as Raw Materials for the Production of Novel Geopolymer Building Materials}, series = {Crystals}, volume = {12}, journal = {Crystals}, number = {5}, publisher = {MDPI AG}, issn = {2073-4352}, doi = {10.3390/cryst12050678}, year = {2022}, abstract = {The increasing number of new construction projects requiring high-quality building products, which, in turn, emit enormous amounts of CO2, runs counter to European and global climate goals. The increasing occupation of valuable landfill space is also an ecological problem. To meet these challenges without having to lower living standards, more ecological building materials should be used in the future. Geopolymers or alkali-activated materials, which, unlike conventional building materials, can be produced and used without a prior burning or calcination process, offer a comparatively low-CO2 alternative. Significant CO2 emissions can already be saved by using this technology. The aim of this work is to investigate whether geopolymers can also be produced from construction and demolition residuals generated by the construction industry in order to counteract the problem of the increasing use of landfill space and, at the same time, to further reduce greenhouse gas emissions in the production of building materials. For this purpose, various residual materials from the construction and demolition industry are investigated by means of XRF, XRD, and IR spectroscopy for their setting behavior by alkaline activation. At the same time, the characteristic values of compressive strength, flexural strength, bulk density, and thermal conductivity, which are important for building materials, are determined in order to test the possible applications of the resulting materials as building materials.}, language = {en} } @article{EitelAumuellerGleissetal.2025, author = {Eitel, Dominik and Aum{\"u}ller, Jessica and Gleiß, Julia and Blum, Michaela and Hagemann, Ulrich and Kottas, Olaf and Panzer, Sabrina and Helbig, Jens and Helbig, Uta and Teipel, Ulrich}, title = {Insight into the formation of carbon-doped titanate nanotubes}, series = {Chemical Engineering Journal Advances}, volume = {24}, journal = {Chemical Engineering Journal Advances}, publisher = {Elsevier BV}, issn = {2666-8211}, doi = {10.1016/j.ceja.2025.100898}, year = {2025}, abstract = {The formation of carbon-doped titanate nanotubes has been studied by using a simplified synthesis approach and extracting samples at different stages during the formation. The hydrothermal synthesis was conducted in a rotary evaporator with a PFA flask under ambient conditions. The resulting samples have been analyzed regarding their morphology, structure and surface area using X-ray diffraction, scanning electron microscopy and gas adsorption measurements. The results show the formation of high surface area nanosheets after a synthesis time as short as 2 h. Even though the surface area at this stage has already reached 212 m2/g, a change in morphology to elongated structures is not observed until 4 h of synthesis, suggesting the formation of the nanotubes during this phase. From that moment on, the d100 value, corresponding to the layer spacing between the nanotube layers, is further decreasing. Additionally, the formation of bundles with longer synthesis times was observed. This effect is discussed to be caused by a self-assembly process of nanotubes assisted by the continuous rotation of the flask in the rotary evaporator. The analysis of the final sample after 24 h revealed remaining carbon shells from the precursor powder. The presence of Ti-O-C bonds observed by X-ray photoelectron spectroscopy proved the incorporation of carbon in the nanotube structure.}, language = {en} }