bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance of Multipor WI as exterior insulation
Authors: Carrigan Svenja , Hartner Marco , Hofmann Markus , Kornadt Oliver , Schoch Torsten 
Published: September 2018

AbstractBackgroundMultipor WI is a mineral‐based interior insulation system with excellent insulation properties. It is dimensionally stable, vapor permeable, and nonflammable.AimsIn this paper the investigation of the processability and functionality of Multipor WI WLF 042 as an exterior insulation system is reported.Materials & MethodsOn the campus of Technische Universität Kaiserslautern, a building was constructed with a new exterior insulation system of Multipor WI WLF 042, of 14 cm thickness. This insulation, which has so far only been used in the building interior, has a heat conductivity of λ = 0.042 W/(mK) and a density of ρ = 90 kg/m3. Its thermal expansion coefficient is α = 10−5/K and its specific heat capacity is c = 0.85 kJ/(kgK). It has a lower density and compression strength than Multipor mineral insulation boards for exterior use do.ResultsTemperature sensors will be implemented in different layers of the building envelope, both in undisturbed areas and at thermal bridges. The building will be monitored for several years. First heat transfer simulations of two thermal bridges of the building demonstrate the excellent insulation properties of WI WLF 042.DiscussionThe investigation of the processability and functionality of Multipor WI WLF 042 as an exterior insulation system is presented. First simulations show the excellent insulation properties of the insulation.ConclusionThe building will be monitored for several years to provide data about the processability and functionality of Multipor WI WLF 042 as an exterior insulation system.
Effects of different autoclaving pressure on mechanical properties of AAC
Authors: Yazal Atilla , Kavas Taner , Soyal A. Doğan 
Published: September 2018

AbstractAutoclaved aerated concrete (AAC) blocks are widely used as a walling material in construction sector in Turkey. They are produced from the mixture of chemically suitable raw materials with water. Prepared slurry is poured into the metallic molds and left to expand and for hardening process in curing area. Thereafter, expended mud, called a cake, is sent to the autoclave stage. This stage is one of the most important process involved in the crystalline structure forming of AAC products. Furthermore, development of mechanical properties of AAC blocks is also strictly related to the conditions of those process. In this study, the effects of different autoclaving pressure and curing time on the mechanical properties of AAC products were investigated to increase production capacity and to save energy by optimizing these parameters. At the first stage, sized specimens were cured in autoclave under varied pressures between 5.5 and 12 bars at different period in a laboratory scale autoclave to determine optimum curing conditions for the samples of G2/350 and G2/400. Before using laboratory scale autoclave, the correlation coefficient between laboratory and industrial one was determined by producing samples from each group. According to the experimental results, the autoclaving process using 10 bars and 5.5 h could be recommended to obtain the best suitable products (for both crystalline structure and mechanical performance) for all groups of AAC blocks. The compressive strength of the specimens were 2.6 and 2.7 MPa for G2/350 and G2/400, respectively when compared with standard one (2.5 MPa) produced under 12 bars and 5.5 h. It is also concluded from this experimental study that the production pressure can be reduced from 12 to 10 bars although all the technical properties of experimental samples remain the same.
Removal of the greenhouse gas methane by using autoclaved aerated concrete as matrix for colonization of methane‐oxidizing bacteria
Authors: Kuever Jan , Remesch Markko , Rabenstein Andreas , Bukowski Gerhard , Kurkowski Harald , Eden Wolfgang 
Published: September 2018

AbstractMethane is an important greenhouse gas causing global warming. Compared to carbon dioxide, the effect on global warming is 34 times higher (probably even higher). Methane is released into the atmosphere by various sources. Landfills containing organic material are one important source. Today, the deposition of organic materials in landfills in Germany is forbidden. In other countries, it is still used. A major problem is that old landfills produce high amounts of methane by the decomposition of organic materials in anoxic zones over a long period of time after closure (more than 50 years). If the concentration of methane in the gas released from the landfill is between 40% and 60% (rich gas), the gas is withdrawn by suction and used for the production of electricity and heat by combustion. Below a level of 30% methane (poor gas), this technique is not efficient and methane is normally discharged into the atmosphere. We isolated methane‐oxidizing bacteria from various habitats and used them for colonization on mixtures of autoclaved aerated concrete (AAC) and sand‐lime brick rubble. Methane‐oxidizing bacteria oxidize methane via methanol, formaldehyde, and formate to carbon dioxide and water. In laboratory experiments, methane‐oxidizing bacteria were grown successfully on these artificial matrices. After adaption periods, they showed good microbial activity and high methane‐oxidation rates. In further experiments, we used this setup for a larger scale field experiment on a landfill site in Bremen. We built up a test field for long‐term measurements under realistic conditions. In this paper, we show the results obtained in our laboratory and field experiments and the problems that occurred. Nevertheless , this setup is an interesting option for the recycling of AAC and other building materials by using them as an active biofilter for the removal of methane emission from landfills.
XRD analysis of phase development and peak broadening during the production of AAC
Authors: Schreiner Juergen , Jansen Daniel , Ectors Dominique , Volkmann Stephan 
Published: September 2018

AbstractThe production process of autoclaved aerated concrete (AAC) is driven by the transformation of mineral phases. During green cake step, strength is developed by the formation of hydrate phases such as ettringite and in larger quantity portlandite. In respective XRD plots, portlandite often shows anisotropic peak broadening due to anisotropic domain morphology. A new implementation in Rietveld refinement allows to refine the peak broadening calculating anisotropic domain sizes. An appropriate model is used to approximate the domains of portlandite. In this way, it is possible to track the mechanism of portlandite growth during hydration and the quantification of phase development during the green cake hydration is performed more precisely. In autoclaved samples, the main phase is tobermorite, which shows anisotropic peak broadening as well. The application of the described approach in a similar way to portlandite enables an advanced refinement. To approximate the domains of tobermorite a triaxial cylinder model is used, so that tobermorite is characterized more accurately. In addition, this method allows to investigate the influence of variations in the chemical composition of raw materials on domain morphology of tobermorite, as exchanged ions like Al3+ make a significant impact. Consequently, a new possibility to analyze the link between mechanical and thermal properties and phase characteristics is given.
Influence of gypsum and limestone, used as mineral additives, on autoclaved aerated concrete properties
Authors: Małecki Marek , Kurdowski Wiesław , Walczak Paweł 
Published: September 2018

AbstractGypsum is a very popular mineral additive used in autoclaved aerated concrete (AAC) technology. In many studies, tobermorite can be synthesized from calcium‐silicate‐hydrate (C‐S‐H) phase under hydrothermal conditions in the presence of gypsum, and its impact on the tobermorite content in the AAC blocks has been discussed. It has been found in a previous study that tobermorite can be synthesized from katoite (Ca3Al2[SiO4]3‐x(OH)4x, where x = 1.5–3.0). Probably, it is the reason why Al additives accelerated tobermorite formation in the AAC process. Another very popular mineral additive is limestone. Calcite, in particular limestone, accelerates the reaction between alite with water and forms C‐S‐H phase, which may have an impact on tobermorite formation under hydrothermal treatment. The impact of limestone and gypsum as additives on phase composition and properties of AAC was determined. In the initial study on the laboratory scale, influence of limestone on the microstructure of AAC was determined. Later, on a technical scale, properties such as compressive strength, dry density, thermal conductivity coefficient, drying shrinkage, and phase composition for blocks of AAC containing gypsum additive or calcite additive were studied.
Effect of filling joints on resistance of walls under vertical loading
Authors: Rybarczyk Tomasz , Drobiec Łukasz 
Published: September 2018

AbstractThe paper describes the results of testing autoclaved aerated concert (AAC) walls on a natural scale. Walls were made of 18‐cm‐wide blocks and thin‐layer joints. Walls were tested with filled and unfilled perpend (vertical) joints. The vertical load was applied by a reinforced concrete rim beam. The load‐bearing capacity and deformability of walls were analyzed.
Quicklime with defined reaction time window for aerated autoclaved concrete production
Authors: Tungulin Dmitry , Behrenberg Birgit , Lutter Jürgen , Wallmeier Werner 
Published: September 2018

AbstractQuicklime, along with quartz sand, cement, and gypsum is one of the most important components for the aerated autoclaved concrete (AAC) production. It provides heat and alkaline environment for the foaming process. It is an excellent source of calcium oxide essential for the formation of tobermorite, the main binding component of AAC. Traditionally, less reactive quicklime was used for the AAC production. However, there is a growing trend toward the usage of more reactive quicklime as it can improve the productivity by, for example, reducing the time of green cake formation, with no effect on the cutting time frame. This can lead to a higher output without necessity to increase the production area. In this study, a small laboratory scale test was performed, with the particular attention to the temperature development, and was applied at the industrial scale. The most common problems involved in the process are highlighted as well.
Reinforced and unreinforced AAC masonry walls supported on deflecting structure
Authors: Piekarczyk Adam 
Published: September 2018

AbstractThe paper presents selected results of wider comparative experimental tests on masonry walls in full‐scale made of autoclaved aerated concrete masonry units. The walls were unreinforced and reinforced. The reinforcement in form of steel wire, glass, and basalt fiber meshes was applied in each masonry bed joint. The walls were subjected to simultaneous incrementing vertical loads and deflection of the structure which they are supported on. The carrying capacity of reinforced walls was up to 1.5 times higher than unreinforced walls. Test results of reinforced walls also showed lower values of deformation angles in relation to the walls without reinforcement for given load and deflection of support. In case of reinforced walls, much smaller widths of the cracks were obtained. The reinforcement allows to keep integrity of walls even after reaching the maximum load and deflection of supporting structure. The paper describes cracking and damaging mechanism of the walls as well.
Usability of chemical additives to accelerate initial curing time of AAC
Authors: Dalgıçer Tuğba , Kavas Taner , Uzgan Uğur 
Published: September 2018

AbstractAutoclaved aerated concrete (AAC) products have been promising materials for the construction sector. For this reason, fast production techniques are becoming more important in this area. In the present study, effects of chemical accelerators on the initial curing time of AAC blocks have been studied. Two different organic additives (Ad1 and Ad2), which are commercial chemical agents used as setting accelerators in cement sector, were studied to investigate effects of curing times of G2/350 receipt. Ad1 and Ad2 were added into the raw materials mix of G2/350 recipe in proportion of 0.3, 0.6, and 0.9% of cement amount in raw materials mix during mixing process. Curing times of expended mud (cake) samples were measured by the hardening apparatus. On the other hand, mechanical, physical, and microstructural analyses of autoclaved samples were investigated. According to the results, it is determined that Ad1 and Ad2 can be used as a curing accelerator in production of AAC blocks. In addition to that Ad1 (in the amount of 0.3%) is the most suitable chemical agent to shorten initial curing time of R1 recipe of AAC.
Utilizing municipal solid waste incineration (MSWI) fly ash as a calcium source to prepare Al‐substituted tobermorite
Authors: Bao Mengyan , Guo Xiaolu , Shi Huisheng , Wu Kai , Zhang Xiong 
Published: September 2018

AbstractTobermorite is one of the main products of autoclaved curing concrete. Utilizing of municipal solid waste incineration (MSWI) fly ash as a calcium source to prepare solid waste–based Al‐substituted tobermorite was explored. The effects of incorporation of MSWI on the reaction products, compressive strength, microstructure, and pore size distribution of solid waste–based wall materials were studied. The ratio of calcium to silicon (C/S) influenced the formation of Al‐substituted tobermorite, and the optimum C/S of the sample without and with MSWI were 1.18 (sample FA‐T‐(1.18) (FA‐T means that fly ash (FA), quick lime, cement, and desulfurization gypsum were used to hydrothermally synthesize solid waste–based Al‐substituted tobermorite)) and 1.30 (sample FA‐MSWI‐T‐(1.30) (FA‐MSWI‐T means that FA, quick lime, MSWI, and desulfurization gypsum were used to hydrothermally synthesize solid waste–based Al‐substituted tobermorite)), respectively. Compared with the sample FA‐T‐(1.18), the compressive strength of FA‐MSWI‐T‐(1.30) increased by 77.5%, the range of main pore size distribution became smaller, and the structure was compact. The microstructure of FA‐MSWI‐T‐(1.30) was fibrous. This work will provide a new way for the utilization of MSWI, which can effectively reduce the pressure on the environment caused by hazardous wastes and provide reference for the basic research on green autoclaved wall materials and heavy metal solidification technology.
Use of European harmonized AAC masonry unit test standards in the UK
Authors: Primmer Peter 
Published: September 2018

AbstractEuropean product standards for masonry units came fully into effect in the UK in 2006 replacing existing UK standard BS6073 Part 1 and 2, which had covered many types of masonry units. EN 771 Part 4 (EN 771‐4) is the product standard specifically for autoclaved aerated concrete (AAC) masonry units with reference to supporting test methods. EN 771‐4 introduced a set of performance requirements to be established by harmonized product tests standards applicable throughout Europe. For the UK, these European test standards proposed changes in the specimen size, preparation, and conditioning together with the introduction of new testing criteria. This paper deals with the implementation of the main harmonized test methods and parameters of importance to the UK and will be of general interest to those attending the conference. There will be comments on the practical aspects of laboratory testing for the key physical characteristics of AAC, the relationship of evaluation methods to the declared finished product properties and how these properties align with UK regulatory requirements. The UK successfully integrated European harmonized test standards to confirm that UK AAC masonry unit products continually meet all performance requirements.
Investigation of the strength development of autoclaved aerated concrete
Authors: Peter Ulrike , Nowak Pawel , Oeinck Hermann , Spicker Volker , Pust Christopher 
Published: September 2018

AbstractAlthough the chemical reactions occurring throughout the production process of autoclaved aerated concrete (AAC) are well‐known today, the physicochemical stability of the greencake during its expansion is not fully understood. The order in which reactions occur during the greencake setting, the reaction speed, their impact on the temperature, the viscosity, or the bubble formation remain unclear. The objective of this research is to better understand the contribution of different factors such as the quality of raw materials like quicklime, cement, or sulfate carrier on the expansion and strength development of the AAC greencake, with a focus on the temperature development. The impact of the raw materials is investigated on the hydration or slaking of the quicklime and on the greencake growth, while the strength development of the stabilizing mineral paste is studied using rheology. It is shown that the temperature profile in the greencake is governing the stability during the greencake growth, and is impacted by the amount and nature of the raw materials used. External temperature control and/or wise choice of raw materials may thus allow for a fundamental revision of mix compositions.
Performance of autoclaved aerated concrete from the designer, developer, and user perspective
Authors: Łaskawiec Katarzyna , Gębarowski Piotr , Misiewicz Lech 
Published: September 2018

AbstractAutoclaved aerated concrete (AAC) products are characterized by relatively favorable compressive strength at low density and high thermal insulation and thus significantly affect the saving of the energy needed for heating buildings, ensuring them a healthy microclimate. The modern technologies of manufacturing AAC, characteristic of AAC products and effects relating with them to show that above production of AAC blocs and applying them to building industry meets the requirements of sustainable development. Over the years, the standardization of AAC was developing. There is currently one “EN 771–4 10 Specification for masonry units – Part 4. Autoclaved aerated concrete masonry units.” It would be necessary to consider additional research to point explore multipurpose use AAC in different European Union countries. The article presents functional properties of AAC, which are important from the construction process and users.
Flexural strength of AAC masonry with bed joint reinforcement
Authors: Piekarczyk Adam 
Published: September 2018

AbstractThe paper presents the results of comparative investigations of flexural strength of unreinforced and reinforced autoclaved aerated concrete (AAC) masonry. The plane of masonry failure was perpendicular to the bed joints plane. Reinforcement in the form of steel wire, glass, and basalt fibers placed in masonry bed joints influenced the higher flexural strength and crack resistance of masonry specimens. Reinforced masonry showed plastic nature after cracking allowing for large horizontal displacements and transferring the substantial loads perpendicular to the surface of masonry in relation to the unreinforced masonry. For most reinforced masonry specimens, the strengthening after cracking was observed which means that the maximum value of load occurred in the cracked masonry.
Effects of thermal insulation on the airborne sound insulation of AAC masonry walls
Authors: Kümmel Julian 
Published: September 2018

AbstractInsulation systems change the acoustic properties of solid walls. A thermal insulation can have positive or negative effects on the airborne sound insulation. The behavior of heavier walls (e.g., calcium silicate bricks or clay bricks) is very well documented. The acoustic behavior of autoclaved aerated concrete (AAC) walls with thermal insulation has not yet been similarly analyzed. Therefore, some tests on the acoustic behavior of AAC walls with thermal insulation were conducted. During the test, different insulation systems were attached to an AAC wall (expanded polystyrene (EPS), elasticized expanded polystyrene (eEPS), phenolic insulation (FP)). The mass of the outer plaster was also variated. Furthermore, an AAC cavity wall was tested. The tests show that the airborne sound reduction index of a monolithic AAC masonry wall can be considerably improved if the appropriate thermal insulation is selected. The use of an elasticized polystyrene insulation leads to an improvement of the sound reduction index between 3 and 5 dB. An additional plaster layer has further positive effects with an overall improvement of up to 9 dB. The tests also proved that a polystyrene insulation with a thickness of 16 cm does not lead to a decline of the airborne sound reduction index.
Automation goes 4.0: The “SMART” AAC factory
Authors: Pottin Frank , Dietz Torsten 
Published: September 2018

AbstractContinuously improving the autoclaved aerated concrete (AAC) production process is one of the key concerns for producers. As a result, new Wehrhahn automation tools have been developed during the past years to facilitate the “SMART” process. The presentation provides information pertaining to the key issues:“SMART” FactoryAdvanced AAC plants are equipped with more than 20 individual electric control sections. Each single machine comes with its own electric control system. The individual controls allow better testing of each machine already in the workshop prior to shipment. We call it “the machine for the socket.”The programs automatically adjust the functional sequences depending on the actual process situation in the plant instead of following a fixed functional sequence. The Wehrhahn Product Control and Information system provides the relevant process data for each individual machine and allows the automatic adjustment of all necessary machine parameters because it knows exactly which AAC product is currently produced and which is coming next.Big DataThe intelligent control systems continuously collect process data in the plant. This facilitates a stable high‐quality production process as the plant can immediately react once parameters change. The key issue is the intelligent process data utilization resulting in automatic reaction of the machines.Industry 4.0The “4th Industrial Revolution” results in a fundamental change in all economic and life aspects. For advanced plants it means to combine the know‐how of all intelligent, decentralized measuring and control systems to one “complete system” making use of all the available data to enable a flexible, optimized, and highly efficient production process.The presentation will accentuate these important key issues on the basis of practical case examples in recently built AAC factories.
AAC in the USA – A second look
Authors: Fouad Fouad H. , Schoch Torsten 
Published: September 2018

AbstractAutoclaved aerated concrete (AAC) made its first debut in the USA in the late 1980s. The new material rapidly attracted the attention of engineers, developers, and the construction industry due to its inherent excellent physical and mechanical properties as well as the ability to be treated similar to wood during construction. Hebel from Germany followed by Ytong came to the USA in the 1990s to setup the first manufacturing plants there. Although both companies have been well established in Europe and had a long history of technical expertise and innovations, they were faced with the problems of verification and redevelopment of most of their technical information for the U.S. market. This paper provides a review of technical developments in the USA that were undertaken to establish AAC as a new construction material and gain the acceptance of both the engineering community and the construction industry. Technical committee activities, standards, and design documents developed specifically for AAC in the USA, based on intensive research programs at key universities in the USA, are discussed. Despite the technical advances in the USA, several market barriers have slowed the progress of AAC. Thoughts are provided with a brief overview of the current and future of AAC in the USA.