We report the experimental results of CeRu 2 Al 10 by means of transport, thermal, as well as 27 Al nuclear magnetic resonance ͑NMR͒ measurements. This material has been of current interest due to indications of heavy-fermion behavior accompanied by the presence of an anomalous phase transition at T o ϳ 27 K. The phase transition has been characterized by marked features near T o in all measured physical quantities. The NMR observations clearly indicated the nonmagnetic ground state in CeRu 2 Al 10 . Furthermore, the opening of an energy gap of about 100 K over the Fermi surfaces was obtained from the analysis of low-temperature specific-heat and Knight-shift data. Above T o , the transport and thermoelectric properties can be well described by a two-band model with reliable physical parameters. Remarkably, the extracted value of quasielastic linewidth q f ϳ 55 K is found to agree well with that observed in the recent neutron-scattering measurement.

This paper provides experimental results on investigations for the validation of photogrammetric strain measurements of ultra-high-performance concrete (UHPC)-prisms subjected to static and cyclic bending-tensile stress. For this purpose, 4 static and 5 cyclic test series were performed. Damage progresses during loading are monitored by means of a digital image correlation (DIC) system and a clip gauge. The control of the DIC by trigger lists and the measurement noise as a function of the measurement rate are examined. All static tests were performed force controlled with the same testing speed and the same measuring rate of DIC and clip gauge. All cyclic tests were performed with the same upper and lower stress levels but with different loading rates. During the static tests, the DIC can be used to make accurate strain measurements before UHPC failure. In the cyclic tests, the measurement noise of the DIC decreases with an increasing measuring rate. The tests performed confirm the control of the DIC by trigger lists for cyclic tests on UHPC-prisms and show that the measurement noise is negligible in static and cyclic tests. K E Y W O R D S cyclic bending tests, DIC, fatigue, photogrammetry, UHPC

Modelling of a mineral dissolution front propagation is of interest in a wide range of scientific and engineering fields. The dissolution of minerals often involves complex physico-chemical processes at the solid–liquid interface (at nano-scale), which at the micro-to-meso-scale can be simplified to the problem of continuously moving boundaries. In this work, we studied the diffusion-controlled congruent dissolution of minerals from a meso-scale phase transition perspective. The dynamic evolution of the solid–liquid interface, during the dissolution process, is numerically simulated by employing the Finite Element Method (FEM) and using the phase–field (PF) approach, the latter implemented in the open-source Multiphysics Object Oriented Simulation Environment (MOOSE). The parameterization of the PF numerical approach is discussed in detail and validated against the experimental results for a congruent dissolution case of NaCl (taken from literature) as well as on analytical models for simple geometries. In addition, the effect of the shape of a dissolving mineral particle was analysed, thus demonstrating that the PF approach is suitable for simulating the mesoscopic morphological evolution of arbitrary geometries. Finally, the comparison of the PF method with experimental results demonstrated the importance of the dissolution rate mechanisms, which can be controlled by the interface reaction rate or by the diffusive transport mechanism.

Precise radial velocities have been measured over one cycle with a time resolution of P /10 for the broad-line (v sin i = 98 km s -1 ) 8 Scuti variable o 1 Eri. The Ca il X8662 and the Paschen X8750 lines have formal 2 K amplitudes of 4.3 km s -1 while the weak lines of Fe I, Si, and Si I show a 2 K amplitude of only 1.2 km s -1 . There are line-profile variations at a level of about 2% of the continuum in the Ca II X8662 line. These variations can be described as the movement of absorption features across the broad line profile. At least four different absorption features are seen moving through the weak Fe IX8689 line over the observed cycle. The average acceleration of the features is 0.0104 ± 0.0027 km s -2 and they are typical of nonradial pulsations seen in other stars. From their separation, and an inferred rotational period of 15.4 hours, we estimate a large value for the nonradial pulsation index \m\. Assuming i = 90°, the derived minimum radius of 1.4 R 0 I s more typical of a dwarf or subgiant.

We report the results of a 27 Al nuclear magnetic resonance ͑NMR͒ study of CeOs 2 Al 10 at temperatures between 4 and 300 K. This material has been of current interest due to indications of hybridization gap behavior below the transition temperature T o Ӎ 29 K. Five 27 Al NMR resonance lines that are associated with five nonequivalent crystallographic aluminum sites have been resolved. For each individual aluminum site, the low-temperature NMR Knight shift goes over a thermally activated response. The temperature-dependent spin-lattice-relaxation rate exhibits a rapid drop below T o , indicative of the formation of an energy gap in this material. We interpret the Knight shift and the relaxation-rate data in light of the presence of a pseudogap with residual electronic density of states at the Fermi level. Moreover, the magnitude of the pseudogap of 120 K is extracted from NMR results, in agreement with the value obtained from the inelastic neutron-scattering experiment.

Improving the durability and sustainability of concrete structures has been driving the enormous number of research papers on self-healing mechanisms that have been published in the past decades. The vast developments of computer science significantly contributed to this and enhanced the various possibilities numerical simulations can offer to predict the entire service life, with emphasis on crack development and cementitious self-healing. The aim of this paper is to review the currently available literature on numerical methods for cementitious self-healing and fracture development using Phase-Field (PF) methods. The PF method is a computational method that has been frequently used for modeling and predicting the evolution of meso- and microstructural morphology of cementitious materials. It uses a set of conservative and non-conservative field variables to describe the phase evolutions. Unlike traditional sharp interface models, these field variables are continuous in the interfacial region, which is typical for PF methods. The present study first summarizes the various principles of self-healing mechanisms for cementitious materials, followed by the application of PF methods for simulating microscopic phase transformations. Then, a review on the various PF approaches for precipitation reaction and fracture mechanisms is reported, where the final section addresses potential key issues that may be considered in future developments of self-healing models. This also includes unified, combined and coupled multi-field models, which allow a comprehensive simulation of self-healing processes in cementitious materials.

In this study, two main alkali sulfates – aphthitalite and calcium langbeinite – fabricated in a laboratory are added to an industrial clinker with low alkali and sulfate content in order to adjust the contents of alkali sulfates in the clinker. Based on measuring the dissolution rate of the alkali sulfates and ion concentration in tricalcium aluminate (C3A)–alkali sulfate–water (H2O) systems compared with gypsum, and testing the heat flow, compressive strength, setting time and linear deformation of cement with different alkali sulfate contents, the differences between the alkali sulfates and gypsum are analysed. It is shown that aphthitalite could not act as a retarder, whereas calcium langbeinite can act to achieve almost the same retardation as gypsum. In view of the volume stability and strength development of cement, aphthitalite has a negative action when the equivalent sodium (Na2Oe) content induced is above 1·42%. The X-ray diffraction analysis patterns and scanning electron microscopy images show that aphthitalite restrains ettringite formation. It is suggested that more attention should be paid to the negative action of aphthitalite when alkali and sulfate contents in clinker appear to be high.

This paper provides preliminary results of a research study on the fatigue behavior of Ultra-High-Performance Concrete (UHPC). Results of an experimental campaign, performed at the Department of Concrete Structures and Structural Engineering of the TU-Kaiserslautern, are firstly proposed. The heterogeneous meso-structure and material degradation of UHPC are studied through cyclic bending-tensile tests. A test set-up is specially developed at the TU-Kaiserslautern to perform such activities. Particularly, different upper stress cycles (namely, cycle reversals) characterized by different force/stress amplitudes are considered and analyzed. The influence of the edge zone on the stress cycles is tested on notched and normal specimens while the results are used for composing a so-called "Wöhler curve" of the materials' fatigue behavior. Damage progress during loading is monitored by means of a Digital Image Correlation system (DIC) and the results are used for improving the measurement accuracy. Based on these results, macroscopic and mesoscale simulations are performed at the TU-Darmstadt's Institute of Construction and Building Materials. A meso-mechanical approach for the numerical analysis of UHPC specimens subjected to low-and high-cycle fatigue actions will be presented. The possibilities of modeling the material fracture response induced by fatigue is taken into account by means of a systematic use of zero-thickness interface elements equipped with a fracture-based model and combined with a continuous damage constitutive law. A plastic-damage based model for concrete subjected to cyclic loading is developed combining the concept of fracture-energy theories with a stiffness degradation, representing the key phenomenon occurring in concrete under cyclic responses. The experimental and numerical activities proposed in this paper stem out from the DFG Priority Program 2020 Project "Cyclic Damage Processes in High-Performance Concretes in the Experimental Virtual Lab".