@article{MeyerKohlstockHauptHeldtetal.,
  author    = {Meyer-Kohlstock, Daniel and Haupt, Thomas and Heldt, Erik and Heldt, Nils and Kraft, Eckhard},
  title     = {Biochar as Additive in Biogas-Production from Bio-Waste},
  series = {ENERGIES},
  journal   = {ENERGIES},
  doi       = {10.3390/en9040247},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170406-31119},
  abstract  = {Previous publications about biochar in anaerobic digestion show encouraging results with regard to increased biogas yields. This work investigates such effects in a solid-state fermentation of bio-waste. Unlike in previous trials, the influence of biochar is tested with a setup that simulates an industrial-scale biogas plant. Both the biogas and the methane yield increased around 5\% with a biochar addition of 5\%-based on organic dry matter biochar to bio-waste. An addition of 10\% increased the yield by around 3\%. While scaling effects prohibit a simple transfer of the results to industrial-scale plants, and although the certainty of the results is reduced by the heterogeneity of the bio-waste, further research in this direction seems promising.},
  subject      = {Festphasen-Fermentation},
  language  = {en}
}
@article{LinnowNiermannBonatzetal.,
  author    = {Linnow, Kirsten and Niermann, Michael and Bonatz, Dennis and Posern, Konrad and Steiger, Michael},
  title     = {Experimental Studies of the Mechanism and Kinetics of Hydration Reactions},
  series = {Energy Procedia},
  journal   = {Energy Procedia},
  doi       = {10.1016/j.egypro.2014.02.046},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170425-31484},
  pages     = {394 -- 404},
  abstract  = {The mechanism and the kinetics of hydration reactions are important for the application of a salt hydrate as a thermochemical heat storage material. MgSO4·H2O and Na2SO4 were chosen in this study because they are both promising candidates for such an application. Considering that the hydration of these salts yields MgSO4·7H2O and Na2SO4·10H2O as the reaction products, the maximum overall heat effect can be calculated from the heat of condensation of water vapor (44 kJ mol-1) and the heats of hydration of 75 kJ·mol-1 (for MgSO4·H2O) and 81 kJ mol-1 (for Na2SO4). Based on the densities of the two hydrated phases, this results in the very high theoretical energy densities of 2.3 GJ·m-3 and 2.4 GJ·m-3, respectively, for MgSO4·7H2O and Na2SO4·10H2O. Not only the energy density is important for the dimensioning of a storage system, but also the kinetics of hydration reactions play a major role for the application as storage material. In the present study, hydration reactions under varying climatic conditions were investigated by using water vapor sorption measurements and in-situ Raman microscopy. Using the phase diagrams, it can be clearly shown that the mechanism and the kinetics depend on the climatic conditions. Below the deliquescence humidity of the lower hydrated phase the hydration proceeds as solid state reaction, whilst above the deliquescence humidity a through solution mechanism takes place.},
  subject      = {W{\"a}rmespeicherung},
  language  = {en}
}
@article{PervyshinYakovlevGordinaetal.,
  author    = {Pervyshin, G.N. and Yakovlev, G.I. and Gordina, A.F. and Keriene, J. and Polyanskikh, I.S. and Fischer, Hans-Bertram and Rachimova, N.R. and Buryanov, A.F.},
  title     = {Water-resistant Gypsum Compositions with Man-made Modifiers},
  series = {Procedia Engineering},
  journal   = {Procedia Engineering},
  doi       = {10.1016/j.proeng.2017.02.087},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170425-31580},
  pages     = {867 -- 874},
  abstract  = {The work has studied the structure and properties of gypsum compositions modified with the manmade modifier based on metallurgical dust and multi-walled carbon nanotubes. The results show that changing the structure of solid gypsum leads to the increase in bending and compressive strength by 70,5\% and 138\% correspondingly, the water resistance increasing and the softening factor reaching 0,85. Modifying gypsum composition with complex additive leads to the formation of amorphous structures based on calcium hydrosilicates on the surface of primary gypsum crystallohydrates that bond gypsum crystals and reduce the access of water.},
  subject      = {Gips},
  language  = {en}
}
@article{SchanzTripathy,
  author    = {Schanz, Tom and Tripathy, Snehasis},
  title     = {Swelling pressure of a divalent-rich bentonite: Diffuse double-layer theory revisited},
  series = {Water Resources Research},
  journal   = {Water Resources Research},
  doi       = {10.1029/2007WR006495},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170425-31592},
  abstract  = {Physicochemical forces are responsible for the swelling pressure development in saturated bentonites. In this paper, the swelling pressures of several compacted bentonite specimens for a range of dry density of 1.10-1.73 Mg/m3 were measured experimentally. The clay used was a divalent-rich Ca-Mg-bentonite with 12\% exchangeable Na+ ions. The theoretical swelling pressure-dry density relationship for the bentonite was determined from the Gouy-Chapman diffuse double-layer theory. A comparison of experimental and theoretical results showed that the experimental swelling pressures are either smaller or greater than their theoretical counterparts within different dry density ranges. It is shown that for dry density of the clay less than about 1.55 Mg/m3, a possible dissociation of ions from the surface of the clay platelets contributed to the diffuse double-layer repulsion. At higher dry densities, the adsorptive forces due to surface and ion hydration dominated the swelling pressures of the clay. A comparison of the modified diffuse double-layer theory equations proposed in the literature to determine the swelling pressures of compacted bentonites and the experimental results for the clay in this study showed that the agreement between the calculated and experimental swelling pressure results is very good for dry densities less than 1.55 Mg/m3, whereas at higher dry densities the use of the equations was found to be limited.},
  subject      = {Bentonit},
  language  = {en}
}
@article{Schuch,
  author    = {Schuch, Kai},
  title     = {Theoretische Grundlagen zum Aggregationsprozess von Wassergl{\"a}sern im Hinblick auf silikatische Beschichtungen},
  series = {Steuerung des Aggregationsprozesses in w{\"a}ssrigen Alkalisilikatsolen durch spezielle Gelinitiatoren und moderate W{\"a}rmebehandlung zum Aufbau einer stabilen Silikatbeschichtung},
  journal   = {Steuerung des Aggregationsprozesses in w{\"a}ssrigen Alkalisilikatsolen durch spezielle Gelinitiatoren und moderate W{\"a}rmebehandlung zum Aufbau einer stabilen Silikatbeschichtung},
  doi       = {10.25643/bauhaus-universitaet.2497},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20160113-24971},
  abstract  = {Der Artikel beinhaltet den theoretischen Teil und die Ergebnisse der Dissertation von Kai Schuch, Bauhaus Universit{\"a}t Weimar, Nov. 2014},
  subject      = {Wasserglas},
  language  = {de}
}
@article{PartschefeldTutalHalmansederetal.,
  author    = {Partschefeld, Stephan and Tutal, Adrian and Halmanseder, Thomas and Schneider, Jens and Osburg, Andrea},
  title     = {Investigations on Stability of Polycarboxylate Superplasticizers in Alkaline Activators for Geopolymer Binders},
  series = {Materials},
  volume    = {2023},
  journal   = {Materials},
  number    = {Volume 16, issue 15, article 5369},
  publisher = {MDPI},
  address   = {Basel},
  doi       = {10.3390/ma16155369},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20231026-64809},
  pages     = {1 -- 14},
  abstract  = {Calcined clays are interesting starting materials to be used as SCMs (supplementary cementitious materials) in cements or to be converted to geopolymers by activation with a high alkaline activator. The adjustment of the properties in the fresh state, especially regarding the consistency of these binders, is almost exclusively achieved by the addition of water, since commercially available superplasticizers seem to be ineffective in low-calcium geopolymer systems. The aim of this study was a systematic investigation of various PCE (polycarboxylate ester/ether) superplasticizers (methacrylate ester PCE: MPEG, isoprenol ether PCE: IPEG, methallyl ether PCE: HPEG) with respect to their stability in different alkaline activators (NaOH, KOH, sodium and potassium silicate solutions). The effectiveness of superplasticizers (SPs) in low-calcium geopolymer binders was verified by rheological tests. Size exclusion chromatography was used to investigate if structural degradation of the superplasticizers occurs. The investigated PCE superplasticizers showed a thickening effect in the low-calcium geopolymer system. Depending on the alkalinity of the activator solution, a degradation process was detected for all the PCEs investigated. The side chains of the PCEs are cleaved off the backbone by basic ester and ether hydrolysis. The highest degree of degradation was found in sodium and potassium silicate solutions. In alkaline hydroxide solutions, the degradation process increases with increasing alkalinity.},
  subject      = {Geopolymere},
  language  = {en}
}
@article{SchirmerOsburg,
  author    = {Schirmer, Ulrike and Osburg, Andrea},
  title     = {A new method for the quantification of adsorbed styrene acrylate copolymer particles on cementitious surfaces: a critical comparative study},
  series = {SN Applied Sciences},
  volume    = {2020},
  journal   = {SN Applied Sciences},
  number    = {Volume 2, article 2061},
  publisher = {Springer},
  address   = {Heidelberg},
  doi       = {10.1007/s42452-020-03825-5},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210804-44729},
  pages     = {1 -- 11},
  abstract  = {The amount of adsorbed styrene acrylate copolymer (SA) particles on cementitious surfaces at the early stage of hydration was quantitatively determined using three different methodological approaches: the depletion method, the visible spectrophotometry (VIS) and the thermo-gravimetry coupled with mass spectrometry (TG-MS). Considering the advantages and disadvantages of each method, including the respectively required sample preparation, the results for four polymer-modified cement pastes, varying in polymer content and cement fineness, were evaluated. To some extent, significant discrepancies in the adsorption degrees were observed. There is a tendency that significantly lower amounts of adsorbed polymers were identified using TG-MS compared to values determined with the depletion method. Spectrophotometrically generated values were ​​lying in between these extremes. This tendency was found for three of the four cement pastes examined and is originated in sample preparation and methodical limitations. The main influencing factor is the falsification of the polymer concentration in the liquid phase during centrifugation. Interactions in the interface between sediment and supernatant are the cause. The newly developed method, using TG-MS for the quantification of SA particles, proved to be suitable for dealing with these revealed issues. Here, instead of the fluid phase, the sediment is examined with regard to the polymer content, on which the influence of centrifugation is considerably lower.},
  subject      = {Zement},
  language  = {en}
}
@article{TutalPartschefeldSchneideretal.,
  author    = {Tutal, Adrian and Partschefeld, Stephan and Schneider, Jens and Osburg, Andrea},
  title     = {Effects of Bio-Based Plasticizers, Made From Starch, on the Properties of Fresh and Hardened Metakaolin-Geopolymer Mortar: Basic Investigations},
  series = {Clays and Clay Minerals},
  volume    = {2020},
  journal   = {Clays and Clay Minerals},
  number    = {volume 68, No. 5},
  publisher = {Springer},
  address   = {Heidelberg},
  doi       = {10.1007/s42860-020-00084-8},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20210804-44737},
  pages     = {413 -- 427},
  abstract  = {Conventional superplasticizers based on polycarboxylate ether (PCE) show an intolerance to clay minerals due to intercalation of their polyethylene glycol (PEG) side chains into the interlayers of the clay mineral. An intolerance to very basic media is also known. This makes PCE an unsuitable choice as a superplasticizer for geopolymers. Bio-based superplasticizers derived from starch showed comparable effects to PCE in a cementitious system. The aim of the present study was to determine if starch superplasticizers (SSPs) could be a suitable additive for geopolymers by carrying out basic investigations with respect to slump, hardening, compressive and flexural strength, shrinkage, and porosity. Four SSPs were synthesized, differing in charge polarity and specific charge density. Two conventional PCE superplasticizers, differing in terms of molecular structure, were also included in this study. The results revealed that SSPs improved the slump of a metakaolin-based geopolymer (MK-geopolymer) mortar while the PCE investigated showed no improvement. The impact of superplasticizers on early hardening (up to 72 h) was negligible. Less linear shrinkage over the course of 56 days was seen for all samples in comparison with the reference. Compressive strengths of SSP specimens tested after 7 and 28 days of curing were comparable to the reference, while PCE led to a decline. The SSPs had a small impact on porosity with a shift to the formation of more gel pores while PCE caused an increase in porosity. Throughout this research, SSPs were identified as promising superplasticizers for MK-geopolymer mortar and concrete.},
  subject      = {Geopolymere},
  language  = {en}
}