Review of the IZF Seminar 2024
The challenges of brick production and application were on the programme of the seminar held by the Institute for Brick and Tile Research Essen e. V. (IZF) last September. Around 50 members of the brick and tile industry gathered in the lecture hall of the hotel Essener Hof in Essen, Germany, on 24 and 25 September to listen to the presentations by IZF employees and their guests. As in previous years, the first day was dedicated to brick production with a special focus on energy-related topics. The second day focussed on brick applications. Guest speakers were Timo Vicktorius (QSM) and Heiner Kruse, Lukas Helm and Daniel Chaker from RPTU Kaiserslautern.
Day 1 - Energy, CO2 and brick production
In the first presentation of the seminar, “Energy consulting and energy efficiency law”, Marzieh Nourbakhsh B. Sc. Sc. informed about the current status of legal regulations and funding programmes. Among other things, she addressed the obligations under Section 8 of the Energy Efficiency Act (EnEfG), the introduction of the DIN ISO 50001:2018 energy management system and the ISO 14001 environmental management system. A transformation concept is required for verification purposes. Companies that were founded by 17/11/2023 must prepare this by 18/07/2025; younger companies have 20 months after foundation. All companies must introduce and audit a management system by 1 July 2027.
In addition, Nourbakhsh explained the federal funding for energy and resource efficiency (BAFA modules), Module 5 Transformation Concept, the Research Tax Allowance (Fzul) and the new funding guidelines for federal funding for industry and climate protection that have been in force since 30 August 2024.
Dipl.-Ing. Eckhard Rimpel then discussed emissions trading and other legal requirements. The benchmarks for the free allocation of emission allowances will be around 50 per cent of the 2020 values from 2026. For process-related emissions that are difficult to reduce, the free allocation is to be reduced from 97 to 91 per cent from 1 January 2028. Rimpel criticised the further development of the Industrial Emissions Directive (IED) with the strengthening of the BAT reference documents (best available technology) as technically clueless. In addition to the previous presentation, he addressed the waste heat and information obligation in §§16f. EnEfG. Finally, Rimpel compared the above-mentioned management systems, including the environmental management system according to EMAS (Eco-Management and Audit Scheme), and discussed the question of which management system is the right choice for your company.
Dipl.-Ing. Alexander Winkel spoke about the recarbonation of bricks. Carbonation is a well-known property of concrete. The calcium hydroxide contained in cement reacts with CO2 present in the air to form calcium carbonate (see DIN 16757:2022, Annex G). As Winkel explained, bricks can also reabsorb CO2 that they lose during the firing process. The absorption capacity is reduced by crystallisation and mineral phase formation. The ability to recarbonate therefore depends on the firing temperature of the bricks.
Alexander Winkel also held the following presentation and discussed saving energy and CO2 by using carbonate-free raw materials. As the brick industry’s Roadmap 2050 explains, CO2-neutral brick production requires carbonate-free clays. However, this would massively increase operating costs. Energy requirements and CO2 emissions during firing are determined by the chemical reactions that take place, i.e. the mineralogy of the clay. Simulations and calculations show that clays with a high carbonate content require a very high heat flow for decomposition. Alternative raw materials can reduce carbonate decomposition, but their suitability must be tested on a case-by-case basis. Adding 30 per cent basalt flour, for example, reduces pressing moisture and CO2 emissions while maintaining the thermal conductivity of the product and increasing its flexural strength.
Eckhard Rimpel discussed the improvement of material properties through the addition of monophosphates. Firing and drying each consume 18 per cent of a brickworks’ energy requirements, shaping 27 per cent. Attempts to use additives to reduce the amount of mixing water and press head pressure have led to energy savings of up to 9 per cent. Additives can also increase moisture conductivity and drying speed and thus energy efficiency during drying. During firing, phosphates can reduce the overall energy requirement and emissions. The additive Cera-Sint, for example, enables savings in gas consumption of between 15 and 25 per cent and in CO2 emissions thanks to a lower peak temperature and shorter temperature plateau. In addition, the additive improves the physical parameters of bricks, such as compressive strength, and prevents efflorescence. Windmill blades can also be ground and used as an aid for sintering and porosity.
Dr Rigo Giese discussed the obstacles to using hydrogen as a fuel under the title “Hydrogen and energy efficiency in the brick and tile industry”. The lower density and lower air requirement of hydrogen mean lower gas radiation and require larger fuel flows than natural gas. Changes in combustion properties place special demands on the tunnel kiln. A decreasing dew point temperature due to increasing water vapour content, increasing volume flow of the fuel and increasing flame temperature at the burner must be taken into account. Tests with 0 to 100 per cent hydrogen showed no effects on the product quality and the temperature distribution in the charge. Guidelines for the use of hydrogen in thermoprocessing systems are: DVGW G 260 Classification of gases and admixtures, DVGW G 265 Systems for the injection of H2, DVGW G 655 Guidelines for H2-readiness gas applications.
Erdem Kanbak B. Sc. presented the research project “Ammonia as a renewable energy source for the brick and tile industry”. The first meeting of the project had taken place the day before in Essen. (see project report in ZI 6/24, p. 20ff.).
Marius Rimpel discussed the possibilities of providing climate-neutral energy for brickworks. In a case study, seven different combinations of process types, energy sources and supply methods were compared in terms of emission effect and investment and energy source costs: Gas firing with natural gas (zero scenario), gas firing with hydrogen from pipeline, from tank or from electrolyser fuelled with grid electricity or with self-generated solar power, electric firing with grid electricity or with self-generated solar power. With hydrogen and renewable energy, it is possible to reduce emissions and emission costs to a large extent. Electrification and renewable energies allow emissions to be almost completely eliminated, depending on the energy source. The energy source is the decisive factor in the cost and emissions balance.
Dr Denny Mathew Alex spoke about the influence of the energy source on the heat transfer coefficients in tunnel kilns. The effective heat transfer coefficient in the tunnel kiln depends on the method of heat transfer (convection and/or radiation), the heat flows in the kiln and the setting thickness. Differences in radiant heat can create an uneven temperature profile in the vertical direction. Circulators can help to homogenise the vertical temperature distribution, as Alex demonstrated using test results on MZ70 and W10 as well as clinker bricks.
Alex also presented the elithe: Electrification of ceramic industries high temperature heating equipment project. The aim is to hybridise brick firing. To this end, semi-industrial tunnel kilns are being retrofitted with heating elements, an internal high-temperature circulation fan and a hybrid FLOX burner.
Dr Denny Mathew Alex and Akash Nagaraj M.Sc. spoke about the possibilities of numerical methods in the brick and tile industry in the last lecture of the first day. Process simulation allows changes to the status quo of the operation to be analysed in advance. However, the method reaches its limits when it comes to gas distribution in the furnace and setting, such as temperature inhomogeneity in the vertical direction or determining the pressure distribution. Flow simulations using computational fluid dynamics (CFD), which provide a detailed understanding of the gas velocity and temperature in the furnace, can fill this gap.
The finite element method (FEM) allows the properties of solids to be calculated or simulated, thereby optimising product quality and production and reducing material costs. Nagaraj explained the principles and discussed areas of application. Structural simulation can be used to determine the resonance frequency of bricks, investigate their structural strength, determine failure modes for various loads and, as a result, optimise them structurally. Similarly, the thermal simulation deals with the heat transfer in bricks and its thermal optimisation, while the acoustic simulation deals with the sound transfer and optimisation of the sound reduction index in bricks.
To help digest the sometimes heavy theoretical fare, the IZF hosted drinks and a buffet on the institute’s premises in Essen-Kray. As always, the institute staff offered guided tours of the workshops and insights into current research projects. The day came to a cosy end, while the night fell gently.
Day 2: Brick applications
In the first presentation of the second day, Timo Vicktorius, Head of the Testing, Monitoring and Certification Centre at QSM, provided information on the current status of standards and tests. In particular, he explained the EN 771-1 requirements for U/P bricks and the test standards EN 772-xx, DIN 20000-401 national requirements for U/P bricks, EN 1344 clay pavers, EN 1304 roof tiles, EN 14411 facade tiles and the test standards EN ISO 10545-xxx also for brick slips, EN 15037-3 ceiling tiles and DIN 20000-129 German requirements, DIN 4159 and DIN 18945 clay blocks. Finally, Vicktorius reported on current and upcoming acquis processes in which the national requirement standards for construction products are to be brought into a harmonised European standard.
In her first lecture, Dipl-Ing. Sandra Petereit presented the microscopic analysis of surface defects in brick materials. Analysing common damage to brick surfaces such as efflorescence, cracks etc. for their various causes ensures the functionality and maintains the aesthetic attractiveness of bricks. As an alternative to the scanning electron microscope (SEM), Petereit presented a combined approach of high-resolution digital microscopy and material analysis. The advantages of the method are easier sample placement than with SEM, simple identification of materials using an internal database and the naming of the recognised elements and materials. For example, white efflorescence on a ridge roof tile proved to be CaSO4, gypsum, which in turn could be due to excessively rapid drying.
Heiner Kruse M. Sc. continued his report from last year on the project “Expanding the application possibilities of monolithic thermally insulating brick masonry in partially loaded exterior wall constructions” with the presentation “Fire resistance in partially loaded exterior wall constructions” (see ZI 6/23, p. 53). Further tests show that lower fire resistance durations result with eccentric support and/or loading compared to the reference tests. The test results showed large scatter. This will be the subject of further research.
Daniel Chaker M. Sc. spoke in his presentation about energy-based seismic design of masonry structures. Earthquake engineering is based on structural idealisations and conservative assumptions in order to simplify calculations. Examples of this are force-based and displacement-based design methods. The energy-based design method, on the other hand, is based on: acting energy, absorbable energy and conversion of the energy spectra into an equation of motion. Chaker explained the methods for determining the acting and absorbable energy and presented the calculations using three case studies. The aim of the project is to develop an economical energy-based design method. Finally, Chaker outlined further fields of research, such as the planning of cyclic wall tests to supplement existing databases.
Lukas Helm touched on the same subject area with his presentation “Economic design of non-load-bearing internal walls for out-of-plane load-bearing capacity under earthquake loading”. Various widely used models for verification in accordance with DIN 4149, EC 8 and KTA 2201.3, among others, provide very conservative results. Important influencing factors that significantly increase the load-bearing capacity, such as vertical stiffness and buckling height, are not taken into account, nor is non-vertical load transfer. This makes it difficult to perform an economical and accurate verification. In contrast, a realistic assessment of the “out-of-plane” load-bearing capacity aims to achieve an economical design concept and reduce conservatism. Helm explained the analytical, experimental and numerical investigations required for this in detail. A calculation tool is also to be developed which, after the input of geometry, boundary conditions, building properties and earthquake effects (spectrum), outputs the storey response spectrum, force-deformation curve of the wall and the verification.
Akash Nagaraj spoke about the design of functional brick surfaces to influence the urban microclimate. The project of the same name, a collaboration between IZF and MFPA Weimar, ran from April 2022 to September 2024 (see ZI 1/24, p. 45 and ZI 4/24, p. 42). The latest experiments on the roof test stand, including the simulation of external weather conditions, showed that despite a surface temperature of up to 70 degrees Celsius on the roof tile, the temperature of the interior and inner surface remained constant at 25 degrees. A hygrothermal building simulation with the software WuFi (Heat and Moisture Instationary) confirmed the experimental results: The higher the reflectance of the roof tiles, the lower the surface temperature profile; As the emissivity decreases, the surface temperature of the roof tiles increases.
The last lecture of the IZF seminar was given by Sandra Petereit: “Image analysis for sorting broken bricks and masonry”. Although around 89 per cent of construction and demolition waste is reused, it is often downcycled. Construction waste, i.e. mixed mineral waste and building material, is a major hurdle here. In order to be able to use brick material in brick production, it must be as completely sorted as possible. Petereit presented the automated image analysis process for sorting brick and masonry rubble using machine learning methods.
Dr Giese thanked the participants at the end of the event and invited them to the next IZF seminar on 9 and 10 September 2025. The traditional joint lunch concluded the event.
