TY - JOUR A1 - de Carvello, J. M. F. A1 - Carvalho Fontes, W. A1 - de Azevedo, C. F. A1 - Brigolini, G. J. A1 - Schmidt, Wolfram A1 - Fiorotti Peixoto, R. A. T1 - Enhancing the eco-efficiency of concrete using engineered recycled mineral admixtures and recycled aggregates JF - Journal of Cleaner Production N2 - Non-conventional densely packed concrete mixtures are proposed and evaluated in this paper using engineered recycled mineral admixtures and recycled aggregates obtained from steel slag, quartz mining tailings, and quartzite mining tailings. High fines content sand-concretes containing coarser- and finer-than-cement recycled powders were designed to obtain blends with broader particle-size ranges and improved packing density. As a result, compressive strength up to 99 MPa, cement intensity up to 2.33 kg/m³/MPa, and consumption of recycled material up to 95 vol% were obtained. Compressive strengths up to 66 MPa and cement intensity up to 2.34 kg/m³/MPa were also obtained with the addition of coarse aggregates to such sand-concrete mixtures, with consumption of recycled material up to 96.5%. The results launch new insights on the role of recycled admixtures and aggregates on the mixture design of cement-based composites regarding efficiency improvement and technological performance. KW - Low-cement concrete KW - Recycled mineral admixture KW - Basic oxygen furnace slag KW - Quartzite mining tailing KW - Packing density PY - 2020 DO - https://doi.org/10.1016/j.jclepro.2020.120530 VL - 257 SP - 1 EP - 12 PB - Elsevier AN - OPUS4-58401 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fritsch, Tobias A1 - Mishurova, Tatiana A1 - Evseleev, Sergei A1 - Serrano Munoz, Itziar A1 - Gollwitzer, C. A1 - Bruno, Giovanni T1 - 3D Analysis of Powder for Laser Beam Melting by Synchrotron X-ray CT N2 - Additive Manufacturing (AM) in terms of laser powder-bed fusion (L-PBF) offers new prospects regarding the design of parts and enables therefore the production of complex structures. The quality of the feedstock material receives increasing attention, as it depicts the first part of the L-PBF process chain. The powder quality control in terms of flowability and powder bed packing density is therefore mandatory. In this work, a workflow for quantitative 3D powder analysis in terms of particle size, particle shape, particle porosity, inter-particle distance and packing density was established. Synchrotron computed tomography (CT) was used to correlate the packing density with the particle size and particle shape for three different powder batches. The polydisperse particle size distribution (PSD) was transformed into a statistically equivalent bidisperse PSD. The ratio of the small and large particles helped to understand the powder particle packing density. While the particle shape had a neglectable influence, the particle size distribution was identified as major contributor for the packing density. T2 - AM- Workshop BAM CY - Online meeting DA - 20.04.2021 KW - Additive manufacturing KW - Laser powder bed fusion KW - Powder KW - Particle size distribution KW - Packing density PY - 2021 AN - OPUS4-53477 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram T1 - Potentials for savings in the production of self-compacting and high strength concrete for precast concrete elements T2 - ICCX Central Europe N2 - Over the course of the last decades, concrete construction has significantly changed from mass application towards sophisticated more innovative, future oriented, and performance based materials technology. Today concrete no longer consists of cement, water, and aggregates, but can be enhanced significantly by using supplementary additions and chemical admixtures. Advancements in admixtures eventually facilitated the development of new concrete types such as self-compacting concrete (SCC) and high performance concrete (HPC) by uncoupling the workability from the water-cement ratio (w/c). While for traditional concrete types the major mixture parameter for the workability and strength were the w/c and the grading of the aggregates, for SCC and HPC the performance parameters are more complicated and the performance depends highly on the powder components. This makes the system more sophisticated and in parallel more prone to scatter during the production. The complexity and difficulty to predict the effects of changes in the process and mixture makes it very difficult to identify the right potentials for savings. T2 - ICCX Central Europe CY - Ossa, Poland DA - 11.02.2016 KW - Rheology KW - Self-compacting concrete KW - High strength concrete KW - Packing density KW - Superplasticizers PY - 2016 SP - 18 EP - 20 AN - OPUS4-36883 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -