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CONCRETE PRODUCTS & CAST STONEwww.cpi-worldwide.com CPI %u2013 Concrete Plant International %u2013 4 | 2025 71as a binder with pozzolanic properties. Furthermore, it was speculated that mechanochemical activation could enhance the pozzolanic reactivity of the material. The SEM analysis revealed the crystalline structure of the residual material, which is initially considered unfavourable in terms of reactivity.To assess the emission behaviour of potentially environmentally relevant contaminants in the tailings material, a percolation test was carried out in accordance with DIN 19528:2023 (Table 1). The leachable concentrations were compared to the assessment criteria for soil material in class BM-F3.The results show that most of the examined parameters are below the applicable limits. Of particular note is the arsenic content of 741 %u00b5g/l, which exceeds the permissible limit of 100 %u00b5g/l according to BM-F3 by a multiple. This exceedance indicates an environmental toxicological risk when utilizing the raw material. Therefore, there is a need for targeted removal or inertization of the arsenic, for example through mineralogical separation, chemical stabilization, or selective processing, before the use of the tailings material can be considered.Investigation of the pozzolanic reactivity of the tailings material to assess its potential as a cement substituteTo evaluate the potential pozzolanic reactivity, the tailings material was first subjected to mechanical fine grinding, achieving a specific surface area of 4,000 cm%u00b2/g (Blaine). Subsequently, a test based on the Frattini method in accordance with DIN EN 196-5:2011 was performed to determine the material%u2019s ability to react with calcium hydroxide (Ca(OH)2) in an aqueous environment.The analysis is based on quantifying hydroxide (OH%u2013) and calcium ion (Ca%u00b2+) concentrations after a storage period of 15 days. For the test, a cement-tailings mixture with 80 mass-% CEMI 52.5 N and 20 mass-% tailings was used.For comparison, additional materials with known reactivity were included: metakaolin and coal fly ash as established pozzolanic additives, as well as limestone powder as a typical inert filler. Another reference sample consisted of pure CEM I. Figure 3 shows that both metakaolin and coal fly ash lie below Masa GmbH GreyHUB Andernach Concrete Block, Pavers + Landscaping ProductsMasa-Str. 2 | 56626 Andernach | GermanyMasa GmbH WhiteHUB Porta WestfalicaAAC + Sand-lime BrickOsterkamp 2 | 32457 Porta Westfalica | GermanyAt Masa, we think of nothing but concrete %u2013 and how to shape it for the building materials industry. The machines we design and build are used for the production of concrete blocks, pavers or landscaping products, aerated concrete blocks and (reinforced) panels as well as sand-lime bricks. In other words, we are real concrete heads with a passion for reliable, high-performance machines.Bj%u00f6rn, one of our clever concrete heads, has developed a tool for paver production lines that provides precise information about the quality of the ongoing production. On the wet side, the system measures products, identifi es defects such as cracks, liftings or cement balls and helps you to reduce waste. When it comes to precise 24/7 inline defect detection and resource savings %u2013 just ask the concrete heads.You want to optimise the use of resources but your building material customers only accept minimal tolerances in product quality.%u201cMy milestone is a discerning eye in your running production.%u201dBj%u00f6rn Herborn, R%u2009&%u2009D DepartmentMasa GreyHUB, Andernachwww.masa-group.com NEW Masa Optical Quality Control Systemma-0000805