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CONCRETE TECHNOLOGY28 CPI %u2013 Concrete Plant International %u2013 4 | 2025 www.cpi-worldwide.comof the mineral foam to be produced. Mineral constituent materials are usually subject to natural fluctuations. Furthermore, the testing of the binders for suitability plays an important role. According to the current state of knowledge, the classification of cements according to the relevant standards is unsuitable, as they are geared towards concrete and different requirements apply compared to the production of mineral foams. It is therefore necessary to establish specific suitability tests for monitoring and selecting suitable constituent materials that can characterize the following three properties:%u2022 foamability,%u2022 solidification behaviour, and%u2022 processing time, i.e. the \to be foamed.To achieve a high degree of automation in the filling process, not only a precise understanding of the process is required, but also suitable measurement technology to control it. The current challenge in determining the setting time lies in the fact that the set mineral foam forms a very sensitive structure, which at present cannot be tested non-destructively using mechanical methods. The hardened mineral foam represents the final product with the desired properties. Of particular interest are its building physics characteristics, such as dry density, thermal conductivity, water vapour diffusion resistance, and water absorption.The processing and handling of foam-filled concrete products and precast elements require a minimum strength, which must be sufficient for subsequent applications such as transport, cutting, or installation. It is important to note that, due to the low foam densities, excessively high strengths cannot be expected, as the dry, hardened mineral foam consists of approximately 95 vol.-% air.In summary, complete and continuous inline quality control remains a significant challenge, with limited practical experience to date. Potential solutions are being explored in the field of non-destructive testing methods (Table 3).Possible applications for concrete blocks and precast concrete elementsThe possible applications listed below originate from research projects carried out at the IAB. Depending on the project, different requirements had to be met, such as the consideration of internal plant processes and the constituent and raw materials on site. The mineral foam mix composition was adapted and optimised in accordance with the requirements.Concrete blocksConcrete blocks equipped with thermal insulation materials are already considered state of the art. The existing hollow-core geometries are suitable for mineral foam filling, provided they are large enough. The filling of mineral foam can be carried out either \or in hardened products. Both approaches have already been tested several times by IAB through manual filling in the factory (see Fig. 3).The automation of the filling process presents a process engineering challenge, for which several development scenarios exist, such as robot-controlled single-chamber filling, the use of multiple parallel filling lances, or the deployment of a mobile filling unit.Table 3: Research and development objectives at IAB for quality assurance of mineral foams.Fresh mineral foam Solidified mineral foam Hardened mineral foamFocus Inline capture%u2022 Flow rate%u2022 DensityCharacterization of solidification behaviourPore size distributionSolutions Non-destructive testing methods%u2022 Optical processes%u2022 Mechanical wave processes%u2022 Thermal processes Optical processes,tomographic processesFig. 3: Manual mineral foam filling of concrete blocks using a hose, directly after forming and compacting the blocks.