TY - JOUR A1 - Cunningham, P. R. A1 - Mezhov, Alexander A1 - Schmidt, Wolfram T1 - Revealing Value from Bioderived Polymers: Effects of Locally Sourced Polysaccharides on the Rheology of Limestone Mixtures N2 - Admixtures are important constituents to enhance the performance of concrete. They allow for more efficient use of binders which can mitigate negative environmental impacts from producing cement-based materials. Commonly used rheology modifying agents like polycarboxylate ethers or cellulose ethers are synthetic or semi-synthetic, respectively. This requires additional energy consumption for their production and global supply chains particularly for many developing regions, which will be large consumers of concrete in the future. However, many locally available bio-based polysaccharides could be effectively used instead. These polymers are often overlooked by engineers and scientists due to their limited distribution and inherent complexity, yet they represent an underleveraged source of precursors for admixtures. This study investigates the action mechanisms of some bio-based rheology modifying agents, i.e., acacia gum and miscanthus gum, and provides a comparison to a conventionally modified starch. The results show that the mechanism of action of these polymers is closely related to the composition of the mixture, mixing regime, and the composition of the aqueous phase. Depending on the agent, either plasticizing or stabilizing effects on rheology can be revealed. T2 - ICBBM: International Conference on Bio-Based Building Materials CY - Vienna, Austria DA - 21.06.2023 KW - Polysaccharides KW - Superplasticizers KW - Hydration KW - Cement PY - 2023 U6 - https://doi.org/10.1007/978-3-031-33465-8_60 SN - 2211-0852 VL - 45 SP - 782 EP - 792 PB - Springer Nature Switzerland AG CY - Switzerland AN - OPUS4-58726 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kruschwitz, Sabine A1 - Munsch, Sarah A1 - Telong, Melissa A1 - Schmidt, Wolfram A1 - Bintz, Thilo A1 - Fladt, Matthias A1 - Stelzner, Ludwig T1 - The NMR core analyzing TOMograph: A multi-functional tool for non-destructive testing of building materials N2 - NMR is becoming increasingly popular for the investigation of building materials as it is a non-invasive technology that does not require any sample preparation nor causes damage to the material. Depending on the specific application it can offer insights into properties like porosity and spatial saturation degree as well as pore structure. Moreover it enables the determination of moisture transport properties and the (re-)distribution of internal moisture into different reservoirs or chemical phases upon damage and curing. However, as yet most investigations were carried out using devices originally either designed for geophysical applications or the analysis of rather homogeneous small scale (< 10 mL) samples. This paper describes the capabilities of an NMR tomograph, which has been specifically optimized for the investigation of larger, heterogeneous building material samples (diameters of up to 72 mm, length of up to 700 mm) with a high flexibility due to interchangeable coils allowing for a high SNR and short echo times (50 - 80 m s). KW - Fire spalling KW - Moisture transport KW - Concrete KW - Cement hydration KW - Sensitivity KW - Supplementary cementitous materials KW - Frost salt attack PY - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-573755 SP - 1 EP - 13 PB - Elsevier B.V. AN - OPUS4-57375 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kruschwitz, Sabine A1 - Lorenzoni, Renata A1 - Telong, Melissa A1 - Lauinger, Robert A1 - Munsch, Sarah A1 - Schmidt, Wolfram T1 - Investigation of the hydration of clinker-reduced cementitious binders by 1H NMR N2 - In this paper, we demonstrate the value of 1H NMR relaxometry for studying the hydration of clinker-reduced, more climate-friendly cementitious binders. The results were obtained on typical CEM I cements and sister samples containing two different reactive agricultural ashes as well as non-reactive biochars as supplementary cementitious materials. The findings prove that time-resolved NMR measurements provide valuable additional information when combined with classical heat flow calorimetry. T2 - International Conference on Electromagnetic Wave Interaction with Water and Moist Substances of the International Society for Electromagnetic Aquametry (ISEMA) 2023 CY - Brisbane, Ausralia DA - 25.09.2023 KW - Carbon emission KW - 1H NMR relaxometry KW - Heat flow calorimetry KW - Cement, hydration KW - Clinker reduction PY - 2023 SP - 1 EP - 3 AN - OPUS4-58936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Robens-Radermacher, Annika A1 - Unger, Jörg F. A1 - Mezhov, Alexander A1 - Schmidt, Wolfram ED - Biondini, F. ED - Frangopo, D. M. T1 - Temperature dependent modelling approach for early age behavior of printable mortars N2 - Structural build-up describes the stability and early-age strength development of fresh mortar used in 3D printing. lt is influenced by several factors, i.e. the composition of the print­ able material, the printing regime, and the ambient conditions. The existing modelling approaches for structural build-up usually define the model parameters for a specific material composition with­ out considering the influence of the ambient conditions. The goal of this contribution is to explicitly include the temperature dependency in the modelling approach. Temperature changes have signifi­ cant impact on the structural build-up process: an increase of the temperature leads to a faster dissol­ ution of cement phases and accelerates hydration. The proposed extended model includes temperature dependency using the Arrhenius theory. The new model parameters are successfully calibrated based on Viskomat measurement data using Bayesian inference. Furthermore, a higher impact of the temperature in the re-flocculation as in the structuration stage is observed. T2 - The Eighth International Symposium on Life-Cycle Civil Engineering (IALCCE 2023) CY - Milano, Italien DA - 02.07.2023 KW - 3D concrete printing KW - Material characterization KW - Structural build-up KW - Thixotropy KW - Model calibration PY - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-582175 SN - 978-1-003-32302-0 SN - 978-1-003-32302-0 VL - 1st Edition SP - 1193 EP - 1200 PB - CRC Press AN - OPUS4-58217 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zhang, K. A1 - Mezhov, Alexander A1 - Schmidt, Wolfram T1 - Thixotropic and chemical structural build-up of cement pastes with superplasticizer under different storage conditions N2 - Synopsis: The paper presents the results of a study on the influence of agitation on the structural build-up of fresh cement pastes using a penetration test. It first presents results about the influence of the penetrating shape’s geometry on the influence on the cement paste specimen. Then, results are shown for the load-deflection curves depending upon time and agitation before testing. Based on the observation of the force required to penetrate the sample, conclusions on the structural build-up can be made. The observations were made over the course of time with samples that were left at rest and partly agitated before testing at different time steps. The setup allows to identify the contribution of the chemical reaction to the structural build-up process. The presence of superplasticizer obviously reduces the load that cement paste can withstand, while the loss of thixotropy is found notably lower than that of neat cement pates T2 - 13th International Conference on Superplasticizers and Other Chemical Admixtures in Concrete CY - Milan, Italy DA - 10.07.2022 KW - Thixotropy KW - Superplasticizer KW - Structural build-up KW - Texture analyzer KW - Penetration test PY - 2022 U6 - https://doi.org/10.14359/51736058 VL - 354 SP - 13 EP - 24 PB - ACI Special Publications AN - OPUS4-58324 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mezhov, Alexander A1 - Zhang, K. A1 - Schmidt, Wolfram T1 - Interactions of Biobased Rheology Modifying Agents with Superplasticizer in Cement Paste N2 - Organic admixtures are an indispensable component of modern concrete. Thus, their purposeful application is not only technically and economically viable but in addition an inevitable tool to make concrete more environmentally friendly. In this context, the use of polysaccharides has increasingly gained interest in the built environment as sustainable resource for performance enhancement. However, due to its origin, biopolymers possess a vast variety of molecular structures which can result in incompatibilities with other polymers present in concrete, such as superplasticizers. The present study highlights effects of the joint application of different types of starches and polycarboxylates with respect to their influence on cement hydration and structural build-up of cement pastes. KW - Polysaccharides KW - Superplasticizers KW - Hydration KW - Cement PY - 2022 U6 - https://doi.org/10.4028/www.scientific.net/CTA.1.563 SN - 2674-1237 SP - 563 EP - 568 PB - Trans Tech Publications Ltd, Switzerland CY - Basel, Switzerland. AN - OPUS4-58325 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zhang, K. A1 - Schmidt, Wolfram A1 - Mezhov, Alexander T1 - Influence of the hydroxypropylation of starch on its performance as viscosity modifying agent N2 - Synopsis: Starch is a commonly used viscosity modifying agent (VMA). The performance of starch as VMA depends on its origin (e.g. potato, corn, cassava, etc.) and corresponding molecular properties, such as molecular weight, ratio between amylose and amylopectin etc. Depending upon the application, the efficiency of starch can be enhanced by hydroxypropylation. The maximum degree of substitution (DoS) cannot be greater than 3.0, which is the number of hydroxy groups per glucose monomer in the polymer. In the current research three potato starches exhibiting the DoS of 0.4, 0.6 and 0.8 were utilised. The influence of the modified starch on the rheological properties and hydration of cement paste, as well as the viscosity of the pore solution were investigated. Our findings show that the starch with the highest DoS increases the dynamic yield stress the most, while the plastic viscosity is less dependent on the DoS. Additionally, starch with the highest DoS retards hydration to lower degree than other starches. T2 - 13th International Conference on Superplasticizers and Other Chemical Admixtures in Concrete CY - Milan, Italy DA - 10.07.2022 KW - Potato starch KW - Rheological KW - Cement hydration KW - Pore solutions PY - 2022 U6 - https://doi.org/10.14359/51736074 VL - 354 SP - 209 EP - 218 PB - ACI Special Publications AN - OPUS4-58320 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mezhov, Alexander A1 - Schmidt, Wolfram A1 - Zhang, H. A1 - Diesendruck, Ch. E. T1 - The effect of the charge density of a comb polyphosphate superplasticizer on the structural build-up of cement paste N2 - Synopsis: Lately, there has been rising attention to superplasticizers (SP) based on polyphosphate esters. However, the influence of the molecular structure of the polyphosphate polymers on time-dependent properties such as structural build-up has not been examined yet intensively. To investigate this effect, three comb polyphosphate superplasticizers with different charge densities were synthesised by free radical polymerisation. Our findings indicate that SP with the lowest and medium charge densities extend the induction period more strongly than the SP with the highest charge density. The reduction of the structural build-up rate is linearly dependent on the dosage and concentration of the functional group of polyphosphate SP in the cementitious system. This study proposes a mathematical equation expressing the relationship between the structural build-up rate during the induction period and the molecular structure of the polyphosphate SP. T2 - 13th International Conference on Superplasticizers and Other Chemical Admixtures in Concrete CY - Milan, Italien DA - 10.07.2022 KW - Admixture KW - Superplasticizer KW - Polyphosphate KW - Structural build-up PY - 2022 U6 - https://doi.org/10.14359/51736079 VL - 354 SP - 255 EP - 262 PB - ACI Special Publications AN - OPUS4-58321 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bessaies-Bey, H. A1 - Khayat, K. H. A1 - Palacios, M. A1 - Schmidt, Wolfram A1 - Roussel, N. T1 - Viscosity modifying agents: Key components of advanced cement-based materials with adapted rheology N2 - Viscosity modifying agents (VMAs) are essential ingredients for the production of flowable cement-based materials. This paper presents an overview of commonly used VMAs and attempts to shed some light on the underlying physics at the origin of their mechanisms of action. The main molecular parameters of VMA controlling the rheological properties of the cement pore solution are highlighted. As the mechanisms of action of VMAs in cement-based materials are closely related to their affinity with the surface of cement particles, the adsorption of the main VMA types is discussed. The effect of VMAs on flow properties and stability of cement-based materials is presented for VMAs added without any superplasticizer, and then in systems incorporating both VMAs and superplasticizers. Finally, the effect of VMAs in enhancing concrete properties to secure adequate performance of different construction applications, and perspectives for future developments of novel cement-based materials made with VMAs are showcased. KW - Viscosity modifying agents KW - Cement KW - Stability KW - Rheology KW - Working mechanism KW - Compatibility PY - 2022 U6 - https://doi.org/10.1016/j.cemconres.2021.106646 VL - 152 SP - 1 EP - 20 PB - Elsevier AN - OPUS4-58396 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bintz, Thilo A1 - Munsch, Sarah Mandy A1 - Stelzner, Ludwig A1 - Lauinger, Robert A1 - Schmidt, Wolfram A1 - Kruschwitz, Sabine T1 - An NMR tomograph for building materials - applications, experimental studies and limitations - N2 - A summary of the possibilities, technical limitations and application examples for a unique NMR tomograph at BAM. T2 - 13th International Conference on Electromagnetic Wave Interaction with Water and Moist Substances (ISEMA), 2021 CY - Kiel, Germany DA - 27.06.2021 KW - Relaxation time distribution KW - NMR imaging KW - Capillary suction PY - 2021 SN - 978-1-7281-8738-9 N1 - Geburtsname von Munsch, Sarah Mandy: Nagel, S. M. - Birth name of Munsch, Sarah Mandy: Nagel, S. M. SP - 106 EP - 110 PB - IEEE AN - OPUS4-53116 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -