This study offers a detailed analysis of water sorption isotherms in raw earth materials, which are increasingly recognized as sustainable alternatives to traditional building materials. The water retention behavior of Compressed Earth Blocks (CEBs) was examined under steady-state conditions using sorption isotherms, which do not fully capture transient moisture buffering performance at the building scale. In this context, we focus on their ability to adsorb and desorb moisture as a measure of their potential to help control indoor humidity. The Dynamic Vapor Sorption (DVS) device was employed to compare the adsorption and desorption isotherms of 1 cm3 cubic samples and powder fragments (2650 mg) of CEBs. Several factors were also investigated, including temperature (15, 23, and 35 °C), repeated wet/dry cycles, and the effects of time on sorption behavior. Using appropriate isotherm modeling, the isosteric heat of water sorption was calculated for the CEB. Results indicated that cubic samples adsorbed up to 23
This article investigates the high-temperature behaviour of thirteen types of limestone used in masonry, focusing on their petrographic properties. Thermochemical and thermomechanical characteristics were evaluated through thermogravimetric analysis and linear measurements up to 1050 degrees C. Both non-destructive tests (P-wave velocity and dynamic modulus of elasticity) and destructive tests (uniaxial compression, three-point bending, and Brazilian splitting) were conducted on specimens of varying geometries. These specimens underwent four distinct heating-cooling cycles at 200, 400, 600, and 800 degrees C. The pore network was assessed using water-accessible porosity (under vacuum), capillary water absorption (up to 600 degrees C), and mercury intrusion porosimetry at 750 degrees C. Limestone undergoes a significant reduction in its physical and mechanical properties at 600 degrees C, primarily due to the differential thermal expansion of its constituent minerals. At 800 degrees C, limestone loses even more of its mechanical properties due to calcite contraction during decarbonatization. Furthermore, limestone thermal sensitivity is also influenced by grain size and by the proportion of fine pores (<10 mu m), which respectively govern the magnitude of internal thermal stresses and the ability of the bonding phase to accommodate thermal expansion.
Earthen construction offers a low-carbon, locally sourced alternative to fired masonry, yet its widespread use is limited by modest strength and brittle post-peak behavior. Bio-based fibers are a promising low-impact stabilizer, but reported strength gains vary widely because fiber morphology and clay mineralogy are seldom controlled independently. This study isolates those variables by combining pure kaolinite, illite, and montmorillonite clays with well-characterized cellulose fibers whose length-to-diameter ratios span two orders of magnitude. Model clay–sand bricks were assessed through compressive testing, static yield stress measurements, and scanning electron microscopy. Fiber morphology proved decisive. Long cellulose fibers (≈ 100 × clay particle size; ≈ 10 × sand grain size) formed an entangled, well-bonded network that increased compressive strength and post-peak ductility of montmorillonite bricks by up to 120
Towards the end of the 16th century, the first known hints emerge that the Lorraine region, and in particular the archbishopric of Metz, was a source of alabaster for sculpture in the principalities and bishoprics of the western part of the Holy Roman Empire. In 1587, a list of available alabaster deposits to be used for the epitaph of Magdalena zur Lippe commissioned by the Landgrave Georg I of Hessen-Darmstadt, mentions an alabaster quarry “in the land of Lorraine, four miles from Metz” exported as far as to Würzburg in present-day Northern Bavaria. Ten years later, Metz alabaster was ordered for the decoration of the Schnellenberg castle in Westphalia. Using geochemical fingerprinting, we found evidence that a common source of alabaster was used in the Metz region and further downstream, in the Mosel and Rhine valleys. Indeed, Alabaster was used broadly from the late 16th century onwards in the major episcopal towns Trier, Bonn and Cologne. We postulate that this “phantom quarry”, so far not identified in our isotopic database of historical European alabaster deposits, is identical with the one mentioned near Metz. Indeed, several alabaster-grade gypsum quarries, still mentioned in 19th century literature, could be found within a range of around 30 km around the town. We will present results of combined archival, geological and geochemical research, conducted in the framework of the Franco-German Materi-A-Net project (https://materi-a-net.uni-koeln.de/en/news/) co-funded by ANR and DFG within the FRAL program.
