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The RILEM TC 281–CCC "Carbonation of concrete with supplementary cementitious materials" is studying the effect of supplementary cementitious materials (SCMs) on natural and accelerated carbonation of blended cements. In this context a large database with carbonation depths over time has been set-up with currently 910 concrete and mortar mixes, which have been tested at different curing conditions. The collected data includes information on chemical composition and physical properties of the raw materials, on mix-design, compressive strength, curing and carbonation testing conditions. Data for a large variety of binders (with up to 94 % SCMs) and mix designs (with w/b ratios ranging from 0.26 to 0.75) were collected from the literature and unpublished material testing projects. Natural carbonation was recorded for several years in many cases, and indoor as well as outdoor results are included. However, in this contribution only lab conditions are considered. Carbonation kinetics are investigated considering the binder composition and mix design. Furthermore, the accuracy of accelerated carbonation testing is evaluated. As described in literature, the w/CaOreactive-ratio is a decisive factor for carbonation resistance but curing and exposure conditions influence the results as well. Even with identical test conditions, the scatter is very large.
For patients under Magnetic Resonance Imaging (MRI) spontaneous respiration is constantly at risk of being impaired by anesthetic drugs or by upper airway obstruction. Therefore, continuous monitoring of the breathing activity is needed to assess adequate ventilation or to detect specific obstruction patterns. The paper describes three MRI compatible respiration sensors based on pure optical technologies developed within the EU FP6 project OFSETH. The sensors are based on fiber Bragg gratings, optical time-domain reflectometry and macrobending effects. The developed smart medical textiles can sense elongation up to 3% while maintaining the stretching properties of the textile substrates for patient's comfort. The OFSETH harness allows a continuous measurement of abdominal and thoracic respiration movement while all vitals organs are free for medical staff actions. The sensors were tested in MRI environment and on healthy adults.
We studied sintering of LTCC-type glass matrix composites (GMCs) consisting of small glass and alumina particles of equal size. Primarily, crystals act as rigid inclusions, decelerating the densification rate. In later stages, they also dissolve, partially increasing the viscosity. Release of alumina finally induces crystallization of alumosilicates, which enables post-firing stability. To study both effects, two model GMCs were prepared: an α-Al2O3 + barium alumoborosilicate glass (BABS)GMC, which shows neither significant dissolution nor crystallization, and an α-Al2O3 + calcium alumoborosilicate glass (CABS)GMC, which dissolves readily and promotes crystallization. The kinetics of shrinkage for both GMC were modeled by utilizing Frenkel theory for the early stage and MackenzieShuttleworth theory for the late stage, assuming that sintering is superimposed by the weighted contributions of triparticle glasscrystal clusters, their random occurrence (ideal mixing), and a shrinkage rate controlled by the GMC effective viscosity. In agreement with modeling, the experimental results showed that the shrinkage rate of BABSGMC decreases progressively for crystal volume fractions Φ > 0.15. The attainable shrinkage is reduced by up to 8% for Φ = 0.45. For the CABSGMC with Φ = 0.25, a reduction of Φ to 0.20 was evident due to partial α-Al2O3 dissolution. This effect was found able to increase the sintering temperature by ~5060 K.