Brick products - production, application and recycling

The annual seminar of the Institute for Brick Research in Essen e. V. (IZF) took place on 13 and 14 September 2022. For two days, the members of the Institute provided information on current research projects under the thematic bracket “Brick products - production, application and recycling”. As in previous years, more than 50 participants from the German and European brick and supplier industry gathered at the Essener Hof.

Lectures of the first day

In his welcoming address, the deputy director of the Institute, Eckhard Rimpel, led the audience through the “colourful bouquet” of lecture topics for the next two days. With building physics and building applications, Rimpel highlighted the special focus of this year’s conference. Dr Dieter Figge and Lukas Helm were welcomed as guest speakers, and the speaker Silke Sabbath was excused due to illness. The very high number of registrations was remarkable.

In the first lecture, Rimpel, standing in for Silke Sabath, presented “Funding opportunities for energy efficiency improvement and energy transition”. A relevant and newly launched funding programme of the Federal Office of Economics and Export Control was presented in detail: “Federal Funding for Energy and Resource Efficiency in Business”, formerly “Energy Efficiency in Business”. Finally, other selected federal and state funding programmes were briefly presented.

Dipl.-Ing. Alexander Winkel presented the Simultaneous Thermal Analysis (STA), which has been in use at the IZF for over a year, in his lecture “STA, Dilatometer and Expulsion Curves: Raw Material Investigations from the Laboratory into Practice”. In comparison with two other examination methods used at IZF, dilatometry and expulsion curves, he discussed the respective advantages and disadvantages. It was particularly emphasised that STA diagrams complement very well with expulsion curves, which allow larger samples and thus more representative results.

The influences on drying in low-energy continuous dryers were discussed by Eckhard Rimpel in the presentation of the same name. Continuous dryers could offer considerable advantages over known processes such as open-air and chamber drying. Rimpel discussed the process based on the measurement results of three tests with different drying temperatures. Based on simulation results, he pointed out advantages of the new concept low-energy continuous dryer for the process such as little risk of curvature and cracking.

The possibility of “H2 bricks: hydrogen as fuel” was discussed by Dr.-Ing. Rigo Giese in the last lecture before the lunch break. According to the test results presented, when up to 30 percent hydrogen is added to natural gas, no serious deviations in the material characteristics and only minor optical changes occur in the test bricks (clinker, roofing and vertically perforated bricks). Ignition behaviour, flame stability and flame monitoring remained unchanged in comparison with pure natural gas, as did the emission behaviour.

Eckhard Rimpel discussed “Synthesis gases as alternative fuels” in the introduction to the afternoon programme of the first day. The discussion focused mainly on biogenic fuels and their technical and legal requirements, including various biomass sources and processes (pyrolysis and gasification). In addition, processes for the production of biogenic hydrogen were discussed. Which alternative fuels should or could be used, Rimpel concluded, can only be determined individually.

This was seamlessly followed by the second lecture by Dr. Rigo Giese: “Fluctuations in gas quality and their effects on energy efficiency and control behaviour”. Based on the presentation of the current range of fluctuations in the composition of natural gas, the lecture discussed correspondingly necessary adjustments to the firing systems as well as measures for recording the gas composition.

In the lecture “Hybrid Heating: Improving Heat Transfer by Internal Atmosphere Circulation”, Marius Rimpel presented a new tunnel kiln concept. By installing an internal circulator, the fuel requirement can be reduced by up to 70 percent using existing technology. Simulations show that the use of baffles and the inclination of the fan help optimise the flow. Due to the high operating temperatures, the development of temperature-resistant ceramic circulators is necessary.

Lars Etscheid gave a lecture on “Experimental investigations of the fire resistance of masonry made of vertically perforated bricks”. Of the three currently possible methods for normative verification testing of fire resistance, only the large-format (3.00 m x 3.00 m) fire test is suitable for thermally insulating vertically perforated bricks. IZF and Technical University Kaiserslautern are currently pursuing three experimental approaches: one-sided temperature loads without pressure load, fire tests based on the test standard DIN EN 1365-1 and large-format fire tests according to the same standard.

Akash Nagaraj informed in his lecture about “Innovative approaches of a decoupling system of infill and non-load-bearing walls made of brick masonry”. The decoupling of partition walls from load-bearing masonry increases the resistance to in-plane and out-of-plane loads. Due to difficult implementation and high costs, a new decoupling concept with elastomers was developed. According to the results of the tests and simulations, the novel decouplings show higher resistances.

Dr. Dieter Figge gave the last lecture of the first day of the seminar with “Masonry made of prefabricated elements - an innovation for the brick industry?” In addition to a short presentation of the history of prefabricated masonry units, the various types of prefabricated units, their production, transport, assembly and testing of the overall stiffness were presented. Thermal bridges and special aspects of assembly were also considered in the lecture.

Cosy get-together at the IZF

After the lectures, the participants gathered on the institute’s premises in Essen-Kray. A marquee in the courtyard with tables and benches as well as a buffet provided an opportunity for exchange and a cosy get-together. A highlight of the evening was the guided tours through the workshops and the presentation of various experimental facilities.

Lectures of the second day

In the first lecture of the second day, “Use of recyclates in clay blocks”, Dipl.-Ing. Alexander Winkel presented experimental results on the use of crushed sands in clay blocks. With decreasing clay mineral content, the compressive strength of the bricks decreases and is particularly dependent on the amount of crushed sand. Exhaust air drying is only possible with sufficiently high temperatures. Swelling clay minerals increase the strength at the expense of water resistance.

Sandra Petereit, standing in for Silke Sabath, spoke about “Reducing the drying energy requirement by using additives to increase the moisture conductivity of plastic masses”. The starting point is the additive use of synthetic polymers to accelerate water transport while retaining the other properties of the operating mass. For the three product groups of front wall tiles, back wall tiles and roof tiles, different additives were tested for their effect on the processing-relevant parameters of shaping, drying, moisture conductivity and firing.

Daniel Baltes explained the use of broken bricks, possible applications and limits as vegetation substrate in the lecture of the same name. Experiments and simulations were used to investigate the effect of using broken brick substrate on green roofs. As a result, broken bricks seem to be very well suited for this purpose. Due to its significantly lower thermal conductivity, the substrate even has a more positive effect on the indoor temperature than conventional substrate.

The normative investigation of the lift-off resistance of roof tiles and current amendments to the corresponding DIN standard EN 14437 were the subject of Lars Etscheid’s presentation. The new DIN EN 14437 (draft version 2022) allows the equivalent consideration of the types of failure as well as the separate testing and evaluation according to the ultimate limit states and serviceability limit states of roof systems. The test stand for determining the lift-off resistance of roof systems at the IZF was also presented.

After the coffee break, Lukas Helm went into the basics, the verification and the state of research on the out-of-plane load-bearing capacity of interior brick walls during earthquakes. He presented the development of an analytical model that allows the testing or confirmation of buckling points in interior walls. The long-term goal is to develop a comprehensive, practicable and economical design model for load-bearing and non-load-bearing brick walls.

Dr. Dieter Figge gave a lecture on “Sound insulation properties of brick masonry”. The state of the art, the problem situation, the relevant DIN standards and their innovations were presented. An overview of the 13 sound transmission paths and the verification methods showed that joints in brick masonry pose a particular problem. The solutions presented include the improvement of the component joint and joint insulation through acoustic decoupling.

Shanmukha Balusu discussed the “Building physics optimisation of brick structures” in the last lecture. By means of studies, the influence of various parameters such as web geometry, dimensions, material properties and surface proportions on thermal conductivity was investigated. It was shown that there is a negative correlation between thermal conductivity and sound insulation. The goal of further research is to determine which combination of parameters provides an optimal ratio of sound and thermal insulation.

In conclusion, Eckhard Rimpel thanked the attendees for their numerous participation. The traditional joint lunch brought the event to a close. The next IZF seminar is scheduled to take place in Essen on 19 and 20 September 2023.