Summary Nowadays, buildings contain more and more synthetic insulation materials in order to meet the increasing energy‐performance demands. These synthetic insulation materials have a different response to fire. In this study, the mass loss and flammability limits of different sandwich panels and their cores (polyurethane (PUR), polyisocyanurate (PIR) and stone wool) are studied separately by using a specially designed furnace. Expanded polystyrene and extruded polystyrene are tested on their cores only. The research has shown that the actual mass loss of synthetic and stone wool‐based cores is comparable up to 300 °C. From 300 °C onwards, the mass loss of PUR panels is significant higher. The mass losses up to 350 °C are 7%, 29% and 83% for stone wool, PIR and PUR respectively, for the influenced area. Furthermore, delamination can be observed at exposure to temperatures above 250 °C for the synthetic and 350 °C for the mineral wool panels. Delamination occurs due to the degradation of the resin between core and metal panels and the gasification of the (PUR) core. The lower flammability limits have been established experimentally at 9.2% m/m (PUR) and 3.1% m/m (PS). For PUR, an upper limit of 74% was found. For PIR and mineral wool, no flammability limits could be established. Copyright © 2017 John Wiley & Sons, Ltd.

This article focuses on the hydration, and associated microstructure development, of β-hemihydrate to dihydrate (gypsum). The sound velocity is used to quantify the composition of the fresh slurry as well as the hardening and hardened—porous—material. Furthermore, an overview of available hydration kinetic and volumetric models for gypsum is addressed. The presented models predict the sound velocity through slurries and hardened products. These states correspond to the starting and ending times of the hydration process. The present research shows that a linear relation between the amount of hydration-product (gypsum) formed and sound velocity (Smith et al., J Eur Ceram Soc 22(12):1947, 2002) can be used to describe this process. To this end, the amount of hydration-product formed is determined using the equations of Schiller (J Appl Chem Biotechnol 24(7):379, 1974) for the hydration process and of Brouwers (A hydration model of Portland cement using the work of Powers and Brownyard, 2011) for the volume fractions of binder, water and hydration products during the hydration process.

Die Aktivierung der Mantelreibung von Bohrpfählen kann nur dann erfolgen, wenn auch eine Setzung des Bohrpfahls stattfindet. Werden Bohrpfähle im Festgestein gegründet, so kann diese Setzung grundsätzlich nicht garantiert werden und die Mantelreibung darf nach den gültigen Regeln der Technik in diesem Fall nicht angesetzt werden. Aus diesem Grund werden derartige Bohrpfähle im Festgestein in der Regel als reine Spitzendruckbohrpfähle dimensioniert, welche die Lasten nur über die Pfahlfußfläche in den Untergrund ableiten.   Mithilfe eines Einbauteils in Form einer Stauchdose, die in den Pfahl eingesetzt wird, konnte unter Laborbedingungen an kleinformatigen Bohrpfählen gezeigt werden, dass eine definierte, vorher festgelegte, reproduzierbare Setzung erreicht werden kann. Die maximal mögliche Setzung kann dabei durch die Konstruktion der Stauchdose in nahezu beliebiger Größenordnung spezifisch vorgegeben werden, sodass keine unkontrollierte, größere, gegebenenfalls für das zu gründende Bauwerk schädliche Setzung, erfolgen kann. Gleichzeitig kann durch die massive Konstruktion der Stauchdose nach erfolgter Setzung (respektive dem „Schließen“ der Dose) der Widerstand über die Pfahlfußfläche uneingeschränkt aktiviert oder angesetzt werden. Die Installation der Stauchdose ermöglicht somit den Ansatz eines größeren Gesamtwiderstandes des Bohrpfahls und somit eine deutlich wirtschaftlichere Gründung als sie derzeit praktiziert wird.

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