bluuebunny/crossref_metadata_2025 huggingface dataset:
Incidence of Nerve Injury After Hip Arthroscopy
Authors: Kern Michael J. , Murray Ryan S. , Sherman Thomas I. , Postma William F.
Published: September 2018

Introduction:

Hip arthroscopy is a commonly performed procedure that carries a notable risk of nerve injury secondary to port placement and the use of axial traction. Sensory neurapraxia of the pudendal nerve and the lateral femoral cutaneous nerve is most common; however, sexual dysfunction and sciatic nerve injury has also been reported. Reported incidence of nerve injury ranges between 1.4% and 5% in the literature, but much of these data are based on unsolicited patient concerns. This study aimed to determine the true rate of nerve injury among this patient population through administration of a validated survey at multiple time points.

Methods:

A prospective study of all patients undergoing hip arthroscopy requiring traction by a single surgeon at our institution was performed. These cases were the first 100 hip arthroscopies performed in practice by the surgeon. Before surgery, all patients were asked about the presence of neuropathic symptoms including sexual dysfunction through administration of a validated questionnaire. The same questionnaire was then administered at several time points postoperatively: on the day of surgery, on postoperative day 2, at the first follow-up visit, and if symptoms persisted, then at each follow-up appointment until resolution of the symptoms. Overall incidence of nerve injury was then calculated. Subgroup analyses were performed to investigate whether traction time, sex, body mass index (BMI), or technically demanding surgical skills affected the incidence.

Results:

This study included a total of 100 patients with an average age of 29 (13 to 62) years and an average BMI of 25. Nerve injury was seen in 13 patients with an incidence of 13%. Specific nerves injured included the pudendal (9), lateral femoral cutaneous (2), sciatic (1), and superficial peroneal nerves (1). Subgroup analysis did not demonstrate a notable association between the risk of nerve injury and increased traction time, sex, or increased BMI. The technically demanding surgical skills was associated with a notable decrease in the traction time, but no notable difference in the risk of nerve injury was observed. Most nerve injuries resolved within 2 weeks (8 of 13), and all cases of nerve injury resolved within 9 months.

Discussion and Conclusions:

The incidence of nerve injury after hip arthroscopy may be markedly higher than previously reported; however, resolution seems to occur as previously found in the literature. Patients should be educated regarding the risk of nerve injury during this procedure.

Level of Evidence:

Level IV
Incidence of Posteromedial Meniscocapsular Separation and the Biomechanical Implications on the Anterior Cruciate Ligament
Authors: Edgar Cory , Kumar Neil , Ware James K. , Ziegler Connor , Reed Dale N. , DiVenere Jessica , Obopilwe Elifho , Cote Mark P. , Arciero Robert A.
Published: September 2018

Purpose:

To report the incidence of posterior medial meniscocapsular junction (PMCJ) separation in patients with anterior cruciate ligament (ACL) injury and to evaluate its biomechanical effect on the ACL.

Methods:

Three hundred thirty-seven consecutive patients undergoing isolated primary ACL reconstruction were retrospectively analyzed for PMCJ lesion. Forty-four patients were identified with PMCJ lesion and studied. Eight cadaver knees underwent biomechanical testing to determine anterior tibial displacement and anteromedial bundle ACL strain in the intact, PMCJ lesion, and PMCJ repair states at 0°, 30°, 60°, and 90° of flexion. Mixed-effects linear regression with Bonferroni correction was used for statistical analysis.

Results:

PMCJ tear incidence with ACL disruption was 13.1%. Specimen with PMCJ tears had statistically increased anterior tibial translation at 30° (1.2 mm;P< 0.01) and statistically increased ACL strain at 30° (24%;P< 0.01) and 90° (50%;P< 0.01). With PMCJ repair, translation reduced (P> 0.05) by 12%, 18%, and 10% at 0°, 30°, and 90° of flexion, respectively. PMCJ repair reduced (P< 0.05) ACL strain by 40%, 39%, 43%, and 31% at 0°, 30°, 60°, and 90° of flexion, respectively.

Conclusions:

A PMCJ lesion was observed in 13% of ACL injuries. This injury contributes to increased ACL strain, and PMCJ repair markedly reduces ACL strain to preinjury levels.
Current Concepts in Orthopaedic Care Disparities
Authors: Pandya Nirav K. , Wustrack Rosanna , Metz Lionel , Ward Derek
Published: September 2018

Healthcare delivery is profoundly affected by race/ethnicity, sex, and socioeconomic status. The effect of these factors on patient health and the quality of care received is being studied in more detail. Orthopaedic surgery over the past several years has paid increasing attention to these disparities as well. Not only do these disparities exist with regard to accessing care but also with regard to the quality of care received and postoperative outcomes. Total joint arthroplasty, hip fractures, and spine surgery represent areas where the effect of these factors has been reported. Not only is it essential for the clinician to understand the extent of care disparities but also the manner in which these disparities affect patient health and outcomes within the orthopaedic surgery setting. Strategies should be devised to minimize the effect of these factors on clinical care and patient health.
Management of Midshaft Clavicle Fractures in Adults
Authors: Wiesel Brent , Nagda Sameer , Mehta Samir , Churchill Ryan
Published: September 2018

Fractures of the clavicle are common injuries that occur across all age groups but are most frequently seen in the young, active patient population. Among the different types of clavicle fractures, those occurring in the middle third of the clavicular shaft are the most common. Historically, most of these fractures were treated by closed means even when notable displacement was present. Recently, there has been a renewed interest in assessing the best treatment option for these patients. Although nonsurgical treatment is a reliable method for treating many of these fractures, more recent data suggest that fractures with notable displacement (>2 cm of shortening or >100% displacement) and/or comminution have better short-term outcomes and lower rates of nonunion with surgical management. Current surgical options include superior plating, anterior-inferior plating, dual plating, and intramedullary nail fixation.
The Translation of Mourid Barghthouti’s Autobiography as a Cultural Encounter
Authors: Nazzal Ayman
Published: September 2018

I saw Ramallah, is an autobiography of Mourid Barghouti, a Palestinian writer and poet. It is an honest and accurate account of a Palestinian who could not adapt to the changes that have taken place during his absenteeism. It can also be considered a precise manifestation of the national and political identity of the author. It is about the abandonment and loss that Palestinians feel both in Palestine and in the Diaspora. I saw Ramallah is the type of literary genre that won the admiration of Edward Said, who considered it as, “one of the finest existential accounts of Palestinian displacement that we now have.” The aim of this study is to explore translational problems and challenges of this autobiography into English by Ahdaf Soueif, the celebrated Egyptian novelist and critic. This study examines some of the translation strategies adopted by Ahdaf Soueif in handling the complexity posed by cultural-bound expressions since such expressions are bound to pose a real challenge for the translator. This study underlies the role of language in reflecting the realities of an entire community; all encompassed as facts, memories, imagination, and fiction.
Alpha-1 Antitrypsin Deficiency in a French General Hospital: Fortuitous Detection rather than Efficient Screening
Authors: Kherouf Hakim , De Faverges Geoffroy , Dumont Pierre , Bourgerette Evelyne , Nguyen Tu , Moquet Olivier
Published: September 2018

Introduction: We studied the characteristics of the screening procedure for alpha-1 antitrypsin at Nevers Hospital (France), together with the performance of serum protein gel electrophoresis for the fortuitous detection of patients with deficiency. Material and methods: We carried out a retrospective study of requests for alpha-1 antitrypsin determination referred to the laboratory during 3 years. We compared these requests with the numbers of patients seen at the hospital and requiring screening according to international recommendations. In parallel, we reviewed all the serum protein gel electrophoresis results obtained during the same period. Results: The laboratory received 102 direct requests for alpha-1 antitrypsin determination, whereas more than 1397 patients presented an indication for screening. No case of alpha-1 antitrypsin deficiency was detected among the 102 patients screened. In parallel, 5551 serum protein gel electrophoresis analyses were carried out at the laboratory. A decrease in the size of the alpha-1 globulin fraction was detected in 68 patients. Seventeen of these patients underwent alpha-1 antitrypsin determinations and 14 were found to have alpha-1 antitrypsin deficiency. Conclusion: Alpha-1 antitrypsin deficiency was more frequently detected fortuitously, by electrophoresis, than through efficient screening. The exploration of alpha-1 globulin deficiencies by serum protein gel electrophoresis thus appears to be still a particularly efficient approach to the detection of alpha-1 antitrypsin deficiency and should be carried out systematically. Furthermore, the testing of all patients with an indication for screening according to international recommendations should be encouraged.
An Investigation on the Forgotten Aspects of Cultures and Influence of Western Education among Communities in Niger State, Nigeria
Authors: K. Ali Hannatu , Al-Yasa’U Mustapha , A. Wushishi Aminu
Published: September 2018

In Niger State, there are more than fifteen different ethnic groups, each having its peculiar cultural affiliations, but the major ethnic groups in the State are; Nupe, Gbagyi, Fulani/Hausa. This paper tends to reflect on certain aspects of cultures which seem to have been forgotten among the three major ethnic groups, with focus on marriage most of whose aspects have been tempered by the influence of Western education. A qualitative method was used with the aim of extracting vital information from the participants regarding the forgotten aspects of cultures. Four aged people who are versed on culture were purposively selected. An in-depth interview, non-participatory observation and document analysis were used as means for data collection. All the participants were interviewed in English and each session of the interview lasted for about an hour to two hours. The interview was recorded, transcribed verbatim and analysed manually. Findings from the study discovered that; most of the beautiful and less expensive cultural practices in marriage have been forgotten, abandoned and changed with expensive and luxurious practices. The paper reviews the traditional marriage practices in the past among the Nupe, Gbagyi and the Fulani, and the influence of Western education on the forgotten aspects. The paper concludes by pointing out effects of the forgotten aspects on our contemporary society, particularly with the increase in population among the youths.
Senior High School English Teachers’ Perceptions on a High-stakes Test (SBMPTN): A Washback Study
Authors: Wahyu Nur Cholis Hafidz , Rizqi Faricha
Published: September 2018

The aim of this research is to explore the washback effect of a high-stakes test on teachers’ attitude and teaching methods used. High-stakes tests refer to tests results of which impact the future of the test takers. In this paper, the high-stakes test is the Entrance Exam of Universities (EEU) in the Indonesia context, namely Seleksi Bersama Masuk Perguruan Tinggi Negeri (SBMPTN). The test determines whether students are qualified to be accepted as university students or not. Therefore, SBMPTN is extremely strict and competitive because students all over Indonesia are eager to pass it. The current study explores washback effect of SBMPTN. In order to gain the data of this survey study, an adopted questionnaire was conducted to a number of 30 senior high school teachers. The data analysis using Statistical Package for the Social Sciences (SPSS) was then explained into descriptive statistic encompassing mean score and percentages. The findings revealed that SBMPTN, as a high-stakes test, has a positive washback on Senior High School English teachers’ attitudes and their teaching methods.
Analysis of Classroom Teaching Candidates’ Speaking Self-efficacy in Terms of Different Variables
Authors: Kuru Oğuzhan
Published: September 2018

Human beings are social creatures by nature and one of their most important characteristics is the multifaceted communication they establish with their environment. There are numerous ways of establishing communication. However, the most preferred manner has always been speech. For the speaking skill to be used effectively, the individual should have self-confidence. Educational institutions are the places where the foundations of self-confidence are laid. In educational institutions where self-confidence is taught, it is fundamental that the educators have self-confidence themselves. The purpose of this study is to determine whether the self-efficacy levels of classroom teacher candidates, who will be teaching in primary schools where the basic characteristics of the speaking skill are taught, display any differences in terms of different variables. The study group of the study consists of students receiving education at the Department of Primary School Teaching, Faculty of Education in a state university in the 2016-2017 academic year. The study group consists of 225 students who were selected through the typical case sampling method, which is one of the purposeful sampling types. With the purpose of collecting data, the ‘Speaking Self-Efficacy Scale (SSES)’ developed by Aydın (2013) consisting of four sub-dimensions with a Cronbach Alpha value of 0.95 was used. SPSS software program (Version 22) was used in the analysis of numeric data. The data was analyzed with the Independent Sample t-test, One Way ANOVA and Kruskal-Wallis tests. According to the results of the study, a significant difference has been determined in the speaking process and listener factor sub-dimensions of the students in favor of the male students. Regarding the grade levels, it was concluded that the upper grade levels regarded themselves as more self-sufficient in the skill of speaking in all of the sub-dimensions.
English Language Use in Malaysian Government and Private Civil Engineering Workplaces
Authors: Shahariah Saleh Noor , Murtaza Siti Fatimah
Published: September 2018

Employers in the engineering sector require certain standard of English proficiency among their employees as the language is widely used for numerous job scopes. In order to understand the current demand of the civil engineering industry on the use of the English language in the workplace, this study was conducted on 20 undergraduates of the Civil and Environmental Engineering Faculty, Universiti Tun Hussein Onn Malaysia who undertook the industrial training. Based on focus group discussions, the participants learned and shared significant use of English language through their industrial training experience. The findings of the study highlighted the activities that were conducted in English for speaking, listening, reading and writing including the language skills. In addition, the amount of time spent on each activity in English was also identified in understanding the importance of English language in the civil engineering sector. The findings of the study are vital in making informed decisions for the design and development of appropriate English language courses for present and future civil engineering students.
Education 4.0 Made Simple: Ideas For Teaching
Authors: Aziz Hussin Anealka
Published: September 2018

Almost everyone is talking about the 4th Industrial Revolution (4IR). The 4IR wave is so strong that change is inevitable, including within the education setting, making Education 4.0 the famous buzzword among educationists today. What is Education 4.0? Do educators really understand it or they simply follow what others are doing. Education 4.0 is a respond to the needs of IR4.0 where human and technology are aligned to enable new possibilities. The paper explains the nine trends of Education 4.0, preference of the 21st century learners, skills for 21st century teachers, share some ideas on how to implement Education 4.0 trends in the language classrooms and students’ feedback on their experience in learning in the Education 4.0 classroom.
Length change behavior of autoclaved aerated concrete at various relative humidity: Comparison between Japanese and Vietnamese AACs
Authors: Nguyen Trong Lam , Asamoto Shingo , Matsui Kunio
Published: September 2018

This paper presents an experimental study on the sorption isotherm and length change behavior of autoclaved aerated concrete (AAC) in both desorption and adsorption processes. Two types of Vietnamese AAC and one type of Japanese AAC with different pore size distributions were used for the tests. The experimental results show that the length change strain of AAC during the adsorption process is mostly larger than that in the first desorption process even though the water content in the adsorption process is lower. Interestingly, a clear expansion in the desorption process at relative humidity (RH) from about 90% to 65% is observed in Japanese AAC but not in Vietnamese AACs; and a significant shrinkage hysteresis at high RH (RH > 65%) is observed in all types of AAC. Both of these behaviors can be explained by capillary tension model taking into account the effect of pore size distribution of each AAC and the explanation is further supported by the reduction of shrinkage in desorption process of AACs that are immersed in solution with shrinkage reducing agent. In addition, the surface energy model is applied to explain the length change during the adsorption process and at lower RH in desorption process for all types of AAC.
Early hydration process of the cement–lime system
Authors: Zhang Hui , Su Yufeng , Yang Zhenghong , Zhang Xiong
Published: September 2018

Autoclaved aerated concrete is a widely used wall material, of which the cementitious materials are cement and lime. In this study, hydration process of the cement–lime system and the influence of initial temperature, water to lime and cement ratio (W/LC), and lime to cement ratio (L/C) on the cement–lime system heat release process were investigated during the first 2 h of hydration. The results indicate that the hydration process of the cement–lime system can be divided into three stages – initial stage, middle stage, and final stage. A prolonged hydration time can be observed with a lower initial temperature, higher W/LC, and lower L/C. The hydration time doubles for every 10°C reduction in initial temperature. A lower W/LC moves the induction and acceleration periods forward but decreases hydration rates if without the effect of the heat released. There might be a critical point of CaO dosage in the cement–CaO system that can change the hydration mechanism. The investigations uncover regulations and effect factors of the hydration process of the cement–lime system which can help to improve the quantity of autoclaved aerated concrete.
Zeolite as a raw material to the AAC production
Authors: Grabowska Ewelina
Published: September 2018

Natural zeolites have a long history as a precious raw material in various fields—in catalysis, environmental protection (as sorbents), in agriculture (in fertilizers), as well as in everyday life (as ingredients of detergents). In the last two decades, the possibility of using them in the building material technology began to be taken into account. The paper considers several ways of application of natural clinoptillolite in the autoclaved aerated concrete (AAC) production. Investigations concern the possibility of zeolite dosing as a cement substitute, part of the binder (raw material in the form of a mixture with blast furnace slag), additive to a sand slurry, and a partial substitute of gypsum (used in the AAC recipe). The testing program includes thermal analysis (TG/DTA), phase composition (X‐ray powder diffraction), microscopic observation (scanning electron microscope/energy dispersive X‐ray spectroscopy), and strength properties of samples autoclaved under existing industrial conditions. The results summary complements the benefits of using zeolite in AAC technology.
The spread of concentrated loads on AAC using digital image correlation techniques
Authors: Fudge Clifford , Edgell Geoff
Published: September 2018

Background

There has debate around the way in which the spread of concentrated loads is assumed in masonry codes in masonry. In addition, there is no data available to assess the spread of loads across the joints of storey height AAC elements.

Aims

The aim was to reconfirm the angle of spread in masonry from a concentrated load and to assess whether this could be applied to storey height elements.

Materials and Methods

A project took to study the strain development in AAC masonry walls subjected to a single concentrated load. A second project studied walls made from AAC storey height panels subjected to uniform vertical load on one element within a set of 3. Test work was carried out using Digital Image Correlation (DIC).

Results

The results clearly justified the current design assumptions in Eurocode 6. In the case of storey height elements, the load effects were transmitted across the vertical joint.

Conclusions

The tests carried out on AAC masonry showed that the spread of concentrated loads is in line of the current recommendations of Eurocode 6. The results justify the when designing with storey height elements, for vertical loading the principals of masonry design can be used.
Performance of Multipor WI as exterior insulation
Authors: Carrigan Svenja , Hartner Marco , Hofmann Markus , Kornadt Oliver , Schoch Torsten
Published: September 2018

Background

Multipor WI is a mineral‐based interior insulation system with excellent insulation properties. It is dimensionally stable, vapor permeable, and nonflammable.

Aims

In this paper the investigation of the processability and functionality of Multipor WI WLF 042 as an exterior insulation system is reported.

Materials & Methods

On 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.

Results

Temperature 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.

Discussion

The 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.

Conclusion

The 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

Autoclaved 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

Methane 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

The 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

Gypsum 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

The 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

Quicklime, 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

The 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

Autoclaved 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

Tobermorite 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

European 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

Although 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

Autoclaved 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

The 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

Insulation 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

Continuously 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” Factory

Advanced 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 Data

The 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 4.0

The “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

Autoclaved 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.