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Alkali‐silica reaction (ASR) causes severe degradation of concrete. The mechanical property of the ASR product is fundamental to the multiscale modeling of concrete behavior over the long term. Despite years of study, there is a lack of consensus regarding the structure and elastic modulus of the ASR product. Here, ASR products from both degraded field infrastructures and laboratory synthesis were investigated using high‐pressure X‐ray diffraction. The results unveiled the multiphase and metastable nature of ASR products from the field. The dominant phase undergoes permanent phase change via collapsing of the interlayer region and in‐planar glide of the main layer, under pressure >2 GPa. The bulk moduli of the low‐ and high‐pressure polymorphs are 27±3 and 46±3 GPa, respectively. The laboratory‐synthesized sample and the minor phase in the field samples undergo no changes of phase during compression. Their bulk moduli are 35±2 and 76±4 GPa, respectively. The results provide the first atomistic‐scale measurement of the mechanical property of crystalline ASR products. [ABSTRACT FROM AUTHOR]

In this article, the specification and application of the new double‐sided YAG laser‐heating system built on beamline I15 at Diamond Light Source are presented. This system, combined with diamond anvil cell and X‐ray diffraction techniques, allows in situ and ex situ characterization of material properties at extremes of pressure and temperature. In order to demonstrate the reliability and stability of this experimental setup over a wide range of pressure and temperature, a case study was performed and the phase diagram of lead was investigated up to 80 GPa and 3300 K. The obtained results agree with previously published experimental and theoretical data, underlining the quality and reliability of the installed setup. A double‐sided, off‐axis laser‐heating system for monochromatic X‐ray diffraction experiments using a diamond anvil cell has been installed at beamline I15 at Diamond Light Source. Measurements of the pressure–temperature phase diagram of Pb demonstrate the reliability of the setup and the high quality of the data. [ABSTRACT FROM AUTHOR]

The first pressure‐induced solid‐phase synthesis of a zeolite has been found through compression of a common zeolite, ITQ‐29 (see scheme, Si yellow, O red). The new microporous structure, ITQ‐50, has a unique structure and improved performance for propene/propane separation with respect the parent material ITQ‐29. [ABSTRACT FROM AUTHOR]