TY - CONF A1 - Schultheiß, Annika L. A1 - Kruschwitz, Sabine A1 - Wilsch, Gerd A1 - Bogner, Andreas A1 - Patel, Ravi T1 - Lessons learnt on quantiative spatial chloride analysis using libs and µXRF N2 - Understanding chloride ingress is crucial in the context of the durability of concrete structures against corrosion. Techniques such as Laser-Induced Breakdown Spectroscopy (LIBS) and Micro X‑ray Fluorescence (µXRF) can provide a 2D representation of chloride ingress. However, obtaining quantitative data from such techniques is not a trivial task. In this study, we focus on factors such as sample preparation, measurement settings, calibration strategy, and post-processing of results which directly affect the outcome of the experiments but are rarely discussed in the literature. T2 - Rilem Annual Week 2024 CY - Toulouse, Frankreich DA - 25.08.2024 KW - Durability KW - Chloride ingress KW - LIBS KW - µXRF KW - Nondestructive testing KW - Imaging PY - 2024 SP - 1 EP - 9 AN - OPUS4-61664 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Miriam E. A1 - Hilbig, Harald A1 - Stelzner, Ludwig A1 - Machner, Alisa T1 - Effect of the chemical composition of synthetic alkali-silica gels on their structure, swelling behavior and water uptake N2 - For alkali-silica reaction (ASR) gels, the relationship between swelling expansion, structure and chemical composition, particularly the effect of aluminum, remains unknown. This study investigates the structure, swelling expansion and associated water uptake of synthetic ASR gels with various Al/Si (0–0.1) and Ca/Si (0.1–0.4) ratios. The results show that aluminum incorporated into the gel structure reduces the overall swelling expansion and the leaching of silicate species during the swelling test. Moreover, they revealed that water in the Al-ASR gels is more tightly bound, reducing the overall water uptake compared to the Al-free ASR gels. Additionally, there is a linear correlation between the maximal swelling results and the ASR gel composition. However, no direct correlation emerged between the amount of water uptake and the free swelling of the ASR gels, which indicates that other factors, like the type of water bonding and pore size of the gels, are decisive for the swelling mechanism. KW - Concrete KW - Alkali-silica reaction (ASR) KW - Durability KW - 1H NMR relaxometry KW - 29Si NMR KW - 27Al NMR KW - FTIR KW - Al-ASR gel KW - Swelling test PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624268 DO - https://doi.org/10.1016/j.cemconres.2024.107596 VL - 184 SP - 1 EP - 18 PB - Elsevier B.V. AN - OPUS4-62426 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Munsch, Sarah Mandy T1 - 1H NMR Relaxometry: A Reliable Tool for Predicting Durability Properties? N2 - Resistance to carbonation and chloride migration are critical durability properties in cementitious construction materials. The ingress of CO2 and chlorides can lead to concrete deterioration and reinforcement corrosion, underscoring the importance of ensuring high resistance to these durability-reducing factors. Traditional methods, such as determinating the carbonation coefficient using standard procedures, are time-consuming and resource-intensive. These tests typically require 42 days of preconditioning, followed by 70 days before the final results can be determined using a phenolphthalein test, for a total duration of 112 days. In addition, some test chambers can only accommodate four samples at a time. In this study, we investigate whether 1H NMR relaxometry can effectively predict not only the carbonation resistance, KAC,3%, but also the chloride migration coefficient, DRCM, and the compressive strength, fc, of concrete, providing a method that could potentially streamline and accelerate the material development process by directing us quickly to potentially well-suited formulations. We performed measurements on non-carbonated fully saturated concrete and mortar samples at 28, 56, and 92 days using the NMR tomograph at BAM (8.9 MHz). Notably, the NMR measurements taken at 28 days showed no significant differences, suggesting that this timeframe is sufficient for meaningful results. The samples analyzed were drill cores, each 70 mm in diameter and approximately 120 mm in height. The NMR features we focused on included the initial amplitude E0, the x and y values of the dominant T2 relaxation time, and the logarithmic mean of the T2 relaxation time distribution. Another key feature was the surface relaxivity, which was determined by comparing the NMR curves with results from mercury intrusion porosimetry. We examined the correlation of these NMR features with the aforementioned durability properties, which were determined in a laboratory on sister samples using standard procedures. No chloride migration tests were performed on the mortar samples, and the carbonation procedure was carried out unter atmospheric conditions. The preliminary results show that the correlation factors for the NMR features with the carbonation coefficients of concrete were particularly remarkable. The strongest correlations were observed for the dominant relaxation time and the logarithmic mean, with values approaching 1. The preliminary results also indicate that there are high correlations between the compressive strength and amplitude-related features. In contrast, no strong correlations are observed for the DRCM. Although the results related to the mortar samples are still being analyzed, these initial correlations suggest that 1H NMR relaxometry could be a valuable tool for early assessment of material properties. Furthermore, the rapid and non-destructive nature of NMR measurements, requiring only a few minutes per sample, suggests that this technique has the potential to significantly accelerate the process of evaluating durability properties in cementitious materials. This capability also paves the way for the use of NMR features as input for AI-driven predictive models. T2 - Magnetic Resonance in Porous Media 2024 CY - Tromso, Norway DA - 26.08.2024 KW - Nuclear magnetic resonance KW - SLAMD KW - Carbonation KW - Durability PY - 2024 AN - OPUS4-61058 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schultheiß, Annika L. A1 - Kruschwitz, Sabine A1 - Wilsch, Gerd A1 - Bogner, Andreas A1 - Patel, Ravi T1 - Lessons learnt on quantitative spatial chloride analysis using LIBS and μXRF N2 - Understanding chloride ingress is crucial in the context of the durability of concrete structures against corrosion. Techniques such as Laser-Induced Breakdown Spectroscopy (LIBS) and Micro X‑ray Fluorescence (µXRF) can provide a 2D representation of chloride ingress. However, obtaining quantitative data from such techniques is not a trivial task. In this study, we focus on factors such as sample preparation, measurement settings, calibration strategy, and post-processing of results which directly affect the outcome of the experiments but are rarely discussed in the literature. T2 - Rilem Annual Week 2024 CY - Toulouse, France DA - 25.08.2024 KW - Chloride ingress KW - LIBS, µXRF KW - Imaging KW - Nondestructive testing KW - Durability PY - 2024 AN - OPUS4-61663 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Su, C. A1 - Shi, J. A1 - Durlo Tambara, Luís Urbano A1 - Yang, Y. A1 - Liu, B. A1 - Revilla-Cuesta, V. T1 - Improving the mechanical properties and durability of steam-cured concrete by incorporating recycled clay bricks aggregates from C&D waste N2 - The output of C&D waste is increasing year by year, among which low-quality recycled brick aggregates (RBAs) have not been well utilized and brought environmental burden. The durability of steam-cured concrete (HCC) is often compromised due to the detrimental effects of this curing regime on the long-term performance and microstructure development of the concrete material. To address this issue, this study investigates the potential of incorporating RBAs to improve the long-term durability of HCC. The results demonstrate that the incorporation of a small amount of RBA (10–20%) not only enhances the 28-d strength of HCC by 2.5–11.3%, but also improves its impermeability by mitigating heat damage effects. The combined application of fine and coarse RBA was found to effectively balance the negative effects of coarse RBA on the performance of HCC. Furthermore, the utilization of RBA in HCC was shown to have economic and environmental benefits. The results of this study demonstrate a simple and effective approach to improve the long-term durability of HCC while promoting the high-value utilization of solid waste. KW - Steam-cured concrete KW - C&D waste KW - Durability KW - Recycled aggregate KW - Environmental benefits PY - 2024 DO - https://doi.org/10.1016/j.powtec.2024.119571 VL - 438 SP - 1 EP - 14 PB - Elsevier B.V. AN - OPUS4-59799 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Durlo Tambara, Luís Urbano A1 - Dehn, F. A1 - Gluth, Gregor T1 - Effect of alkali-activated concrete composition on carbonation rate under accelerated and natural conditions N2 - While alkali-activated binders offer certain advantages over traditional Portland cement binders, particu¬larly in terms of resistance against chemical attacks and potentially environmental footprint, their degradation mechanisms remain incompletely understood at present, specifically carbonation. Thus, this study investigates the impact of natural and accelerated carbonation (1% and 4% CO2) on three different compositions of alkali-activated concretes: 100% calcined clay (C100) binder, 100% ground blast furnace slag (S100) binder, and a 40% calcined clay and 60% blast furnace slag blend (C40S60). C100 concretes exhibit faster carbonation kinetics, with five times greater natural carbonation depths than S100. This difference diminishes under accelerated carbonation, showing a 1.5 times difference for 1% CO2 and complete carbonation for 4% CO2 at 90 days. The results thus confirm that accelerated carbonation testing of low-Ca alkali-activated concretes yields results that are not representative of natural carbonation. The C40S60 sample demonstrates a carbonation profile similar to a CEM I concrete, i.e., a high carbonation resistance. Microstructure analysis indicates the formation of three polymorphs of calcium carbonate for S100 (calcite, vaterite, and aragonite), with a higher CO2 concentration favouring aragonite over vaterite. C100 exhibits no calcium carbonates; instead, sodium carbonates form, including trona for 4% CO2 and natrite for both accelerated tests. C40S60 shows calcium and sodium carbonates, although to a lesser extent, containing predominantly calcite and minor signals of natrite. Suitable compositions, like C40S60, prove as effective during natural or accelerated carbonation tests as conventional Portland cement concrete. T2 - RILEM Spring Convention 2024 CY - Milan, Italy DA - 10.04.2024 KW - Alkali-activated concrete KW - Carbonation KW - Calcined clay KW - Slag KW - Durability PY - 2024 AN - OPUS4-59915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fornacon-Wood, C. A1 - Stühler, M. R. A1 - Gallizioli, C. A1 - Manjunatha, B. R. A1 - Wachtendorf, Volker A1 - Schartel, Bernhard A1 - Plajer, A. J. T1 - Precise construction of weather-sensitive poly(ester-alt-thioesters) from phthalic thioanhydride and oxetane N2 - We report the selective ring opening copolymerisation (ROCOP) of oxetane and phthalic thioanhydride by a heterobimetallic Cr(III)K catalyst precisely yielding semi-crystalline alternating poly(esteralt- thioesters) which show improved degradability due to the thioester links in the polymer backbone. KW - Sulfur containing polymers KW - Durability KW - Weathering KW - Synthesis PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-590762 DO - https://doi.org/10.1039/d3cc03315e SN - 1364-548X VL - 59 IS - 76 SP - 11353 EP - 11356 PB - RSC AN - OPUS4-59076 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schartel, Bernhard T1 - Small but Great – Multifunctional Graphene in Rubber Nanocomposites N2 - A few layer/multilayer graphene (MLG) with a specific surface area of BET ≥ 250 m2/g is proposed as an efficient multifunctional nanofiller for rubbers. The preparation method, i.e., ultrasonically-assisted solution or latex premixing of master batches followed by conventional two-roll milling, strongly influences the dispersion in the elastomeric matrix and is fundamental for the final properties. When homogenously dispersed, single stacks of only approximately 10 graphene sheets, with an aspect ratio of ca. 35, work at low loadings, enabling the replacement of large amounts of carbon black (CB), an increase in efficiency, and a reduction in filler load. The appropriate preparation yielded nanocomposites in which just 3 phr are sufficient to significantly improve the rheological, curing, gas barrier properties, electrical and thermal conductivity, as well as mechanical properties of different rubbers, as shown for chlorine-Isobutylene-Isoprene rubber (CIIR), nitrile-butadiene rubber (NBR), natural rubber (NR), and styrene-butadiene rubber (SBR).[1-5] 3 phr of MLG tripled the Young’s modulus of CIIR, an effect equivalent to 20 phr of CB. The stronger interactions between MLG and NR or SBR also resulted in a reduction in the elongation at break by 20% and 50%, respectively, while the same parameter was hardly changed for CIIR/MLG and NBR/MLG. CIIR/MLG and NBR/MLG were stiffer but just as defomable than CIIR and NBR. The strong reinforcing effect of 3 phr MLG was confirmed by the increase of greater than 10 Shore A in hardness. MLG reduces gas permeability, increases thermal and electrical conductivities, and retards flammability. We investigated MLG also as a synergist for reducing the aluminium trihydrate loading in flame retardant hydrogenated acrylonitrile-butadiene (HNBR), polybutadiene chloroprene (BR/CR), and chlorosulfonated polyethylene rubber(CSM).[6-8] The higher the nanofiller concentration is, the greater the improvement in the properties. For instance, the permeability decreased by 30% at 3 phr of MLG, 50% at 5 phr and 60% at 10 phr, respectively. Moreover, the MLG nanocomposites improve stability of mechanical properties against the effects of weathering. In key experiments an increase in UV-absorption and a pronounced radical scavenging were proved as stabilizing mechanisms. In a nutshell, MLG is an efficient multifunctional nanofiller ready to be used for innovative rubber development. T2 - 34th PDDG Conference CY - Dubrovnik, Croatia DA - 11.06.2023 KW - Graphene KW - Nanocomposites KW - Reinforcement KW - Antioxydant KW - Flame retardant KW - Durability PY - 2023 AN - OPUS4-57693 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schartel, Bernhard T1 - Weathering Resistance of Halogen-free Flame Retardancy in E&E Plastics N2 - - Durability of fire retardancy - Impact of different exposure conditions - Degradation with respect to different fire properties/tests T2 - Fire Resistance in Plastics CY - Cologne, Germany DA - 28.11.2022 KW - Durability KW - Flame retardant KW - Thermoplastic Polyurethane KW - Cable KW - EVA KW - Weathering PY - 2022 AN - OPUS4-56444 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Voigt, Marieke A1 - Gardei, Andre A1 - Meng, Birgit ED - di Prisco, M. ED - Meda, A. ED - Balazs, G.L. T1 - The adaption of the set-up for gas permeability measurements for ultra-high performance concrete N2 - In the framework of this project, a steam pressure vessel was to be developed from ultra-high perfor-mance concrete (UHPC) to withstand process temperatures of 200 °C and the respective steam pressure of 15,5 bar. To guarantee the long-term water vapour tightness of the system, the permeability of two UHPC mixtures were tested after long-term cyclic autoclaving. As UPHC shows a high density and therefore low permeability, measurements after the RILEM-Recommendation (TC 116-PCD) reached their detection limit. Therefore, the measurement set-up was adapted to measure the permeability of highly dense UHPC more reliably and quickly. This adaption includes measurements in a higher pres-sure range, the change of sample size thickness and the usage of Ar as a medium compared with the RILEM Recommendation. Additionally, the system was equipped with two pressure sensors and Ar-flowmeters to guarantee a continuous record of the experimental parameters. The new system was tested and evaluated by comparing measurements with the RILEM recommended system. Preliminary results show that the adapted system is capable to provide efficient and reliable results of concrete with low permeability. T2 - 14th fib PhD Symposium in Civil Engineering CY - Rom, Italy DA - 05.09.2022 KW - Durability KW - UHPC KW - gas permeability PY - 2022 SN - 978-2-940643-17-2 SN - 2617-4820 VL - 58 SP - 353 EP - 359 AN - OPUS4-56862 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -