This study introduces a new approach towards systematically defining the role of different mineral components in clay-rich earthen mineral binders. It is part of the collaborative research center TRR277 “Additive Manufacturing in Construction (AMC)” and started in 2024. Therefore, even though the knowledge gained in the process could potentially be applied to other existing earth-building techniques, it will presently be used to optimize earthen binders for novel Earth Additive Manufacturing (EAM) methods. The goal is to understand the manner in which the structural and compositional variability of clay minerals, affects the plasticity of earthen binders and controls their behavior during the mixing, extruding, compacting, and drying stages. To enable a systematic investigation, a matrix of earthen material compositions will be created, with the goal of having the clay mineral component as the only variable. Additionally, model systems with varying amounts of kaolinite and illite will be achieved through mixtures of different clay-rich products. Special focus will be brought to the surface properties of the different material mixtures, and how they reflect on the flow properties and drying behavior of the binder.
Der Klimawandel lenkt den Fokus im Bauwesen zunehmend auf die Reduktion von Treibhausgasen und die Förderung nachhaltiger Materialien. Baustoffe wie Lehm gewinnen dank ihrer ökologischen und bauphysikalischen Vorteile an Bedeutung. Eine zentrale Herausforderung stellt die Definition standardisierter Prüfmethoden für Stampflehm dar.
Dieser Beitrag analysiert Forschungsergebnisse zur Geometrie von Stampflehmprobekörpern mittels Literaturrecherche und vergleicht experimentelle Untersuchungen sowie relevante Normen und Testmethoden. Die Auswertung zeigt, dass äußere Einflüsse wie Mischungszusammensetzung, Verdichtungsenergie, Gesteinskörnung und Tonminerale eine zentrale Rolle spielen. Eine Vereinheitlichung von Probengeometrie, Lagerung und Prüfverfahren ist essenziell, um reproduzierbare Ergebnisse zu erzielen und die mechanischen Kennwerte von Stampflehm vergleichbar zu machen. Ziel ist es, einheitliche Standards zu entwickeln, um die Stampflehmbauweise in der Praxis zu fördern.
Das ERiMa-Projekt der Fachhochschule Potsdam verfolgt das Ziel, ein praxistaugliches Konzept für die Planung, Bemessung und Ausführung der statisch wirksamen Risssanierung von Massivlehmbauten zu entwickeln. Im Fokus steht die Übertragung des aus dem Mauerwerksbau etablierten Verfahrens der Rissvernadelung auf den Lehmbau, wobei die spezifischen materialtechnischen und baustatischen Eigenschaften von Lehm berücksichtigt werden. Im Rahmen des Forschungsprojekts werden Auszugsversuche durchgeführt, bei denen verschiedene Kombinationen von Untergründen, Ankerstäben und Mörteltypen untersucht werden. Darüber hinaus sind unter anderem noch Materialanalysen und FEM-Simulationen im Forschungsprogramm vorgesehen. Ziel ist es, die relevanten Einflussfaktoren zu identifizieren, um langfristig einen Tragfähigkeitsnachweis für die Rissvernadelung in Massivlehm unter Berücksichtigung der Stoffvielfalt von Lehmwänden zu entwickeln. Dadurch soll eine belastbare Nachweisführung für instandgesetzte Wandkonstruktionen aus Lehm gewährleistet werden.
Im Fokus des vorliegenden Beitrags liegt die Beschreibung, Analyse und Bewertung von vier verschiedenen Produktionsstrategien für die Herstellung der formgepressten Lehmsteine: lokale Produktion, regionale Produktion, überregionale Produktion und globale Produktion. Bei den vier Varianten werden sowohl die logistischen als auch die ökologischen Aspekte der jeweiligen Strategien beschrieben und untersucht, um eine fundierte Grundlage für die Optimierung der Material- und Ressourceneffizienz zu schaffen. Ziel ist es, durch eine systematische Nachverfolgung und Dokumentation der einzelnen Produktions- und Logistikschritte eine optimierte Herstellungsstrategie der Lehmsteine zu erreichen. Darüber hinaus wird versucht, eine erste quantitative Annäherung an eine ökologische Sachbilanzstudie entlang des gesamten Produktions- und Logistikprozesses zu erstellen. Dies ermöglicht einen Vergleich der vier betrachteten Strategien hinsichtlich ihrer ökologischen Bilanz. Die Ergebnisse sollen dabei helfen, eine fundierte Entscheidung zu einer optimierten Produktionsstrategie zu treffen.
This article briefly describes the project background, timelines, structural data, actually achieved milestones and current stage of project of the bridge over Gottleubavalley in Pirna, Saxony, Germany. The bridge is being built using incremental launching method, the main challenges of the launching process are briefly described together with some learning points.
The winning design from the architectural competition in 2006 proposed very slender (1 to 35 !) hybrid steel-concrete semi-integral frame crossing the 70m deep and 1000m wide valley with nine spans (92 – 116 – 120 – 120 – 124 – 108 – 92 – 76 m) with maximum span length of 124m. The paper describes the challenges the team faced during the preparation and launching of a very slender bridge deck with deflections up to 6m when touching down at the bridge pier. By the time of the venue, the incremental launching will be already finished, and the lowering works will be in progress.
This contribution describes the architectural and structural solutions of a unique pedestrian footbridge in Hradec Králové. The new significant construction was built over the Elbe River in the pedestrian area. The bridge design was challenging for architects, planners even though contractors, especially due to accounting for the influence of shipping traffic. Completed structure has two asymmetrical spans, whereas the main span across the river is 69 m long. In the final static scheme, the structure forms a virtual Vierendeel truss of variable height. A slender UHPFRC bridge deck supported by a pair of cables through thin steel crossbars creates a delightful bridge, which has become a new symbol of the city.
The increased traffic loads of the last decades led to an overload of the existing infrastructure. Especially for orthotropic steel decks of bridges, which are prone to fatigue fractures, this have led to structural damages of different categories. With respect to category 2 damages and their retrofit, this paper presents results of fatigue tests on the nonwelded constructional details of an old, demolished orthotropic steel deck. The samples were extracted from a highway bridge with an orthotropic steel deck built in Germany in the 1970s. In comparative fatigue tests on identical constructional details made of new material with the same steel grade, the remaining fatigue strength was determined. Based on the problem of manganese sulfides in old steels the potential of the repair method by cold joining techniques was emphasized. Characteristic load-bearing capacities for a Eurocode 3-compliant design of a structural blind fastener were determined and their use in a pilot project was reported.
Relevant aspects in the design of modular expansion joints are the high fatigue stress caused by heavy load traffic and the corrosion protection. Currently, corrosion damage is often not limited to the traversable surface. Therefore, more durable expansion joints are highly desirable to extend their service life. The FOSTA research project P1574 resulted from the need for durable expansion joints and thus is aimed at hot-dip galvanized structures. In this project about 14.000 individual damages on 6.300 modular expansion joints were evaluated, relevant hot-dip-galvanizing parameters were investigated and recommendations for hot-dip galvanizing-compatible constructions were made. In addition, the fatigue strength of existing constructions has been evaluated with regard to the current and upcoming version of Eurocode 1993-1-9. This evaluation will be verified in the course of cyclic tests and numerical investigations. A monitoring concept is to be designed according to the requirements of the modular expansion joints and the corresponding neuralgic points.
Sky Bridge 721 was opened on 13 May 2022.
It is located in the area of the Kralicky Sneznik mountain massif in the area of the Dolni Morava Mountain Resort. It was built in two years and spans the valley between the two ridges Slamnik and Chlum with a length of 721 metres.
It has become a new landmark of the region, although in reality it is almost invisible when viewed from a distance. It winds like a thin thread below the horizon of the mountain ridge, suspended between the sky and the ground, so that it does not interfere with the view of the surrounding countryside.
It was a real challenge to bridge such a wide valley at a height of nearly 100 metres and to achieve a subtle line of the footbridge that would not disturb the silhouette of the mountain massif.
This is the story of the whole process, from the design to the statics, construction, design and implementation, that the TAROS NOVA a.s. team had to overcome during the implementation of the footbridge.
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