extern

Die AKR‐Schadensevolution von Betonfahrbahndecken ist in der Anfangsphase durch eine Dunkelfärbung der Oberfläche im Fugenbereich gekennzeichnet. Es wird vermutet, dass eine erhöhte Durchfeuchtung der Betonrandzone ursächlich für diese Erscheinung ist. Vor diesem Hintergrund wurde exemplarisch eine Fahrbahnplatte eines repräsentativen Bundesautobahnabschnitts systematisch mit verschiedenartiger zerstörungsfreier Prüftechnik vor Ort untersucht. Die Ergebnisse der zunächst erfolgten großflächigen Durchmusterung …

Dunkelfärbung der Betonfahrbahndecke im AKR-Kontext Read More »

Moisture and ionic transport under non-saturated condition is an important, but poorly understood transport phenomena particularly for mature systems containing supplementary cementitious materials. This paper investigates the moisture and chloride profiles of 3-year old mortars containing Portland cement (OPC), slag and silica fume (SF) after long-term (30–48 months) wick action exposure in 1.09 M NaCl solution. Moisture profiles were measured with 1H NMR relaxometry and …

Wick action in mature mortars with binary cements containing slag or silica fume – The relation between chloride and moisture transport properties under non-saturated conditions Read More »

The maintenance of existing concrete structures gains increasing importance. New challenges within this topic are the durability modelling of conservation measures and the timing of renewing them. One necessary step for the solution of these new challenges are needs-oriented non-destructive testing methods. For the first time, ever, a mobile nuclear magnetic resonance (NMR) sensor allows …

Performance of Mobile NMR for Non-destructive Analyses of Existing Concrete Structures – Influencing Factors Read More »

A large number of infrastructural concrete buildings are protected against aggressive environments by coating systems. The functionality of these coating systems is mainly affected by the composition and thickness of the individual polymeric layers. For the first time ever, a mobile nuclear magnetic resonance (NMR) sensor allows a non-destructive determination of these important parameters on …

Measuring the layer thicknesses of concrete coatings by mobile NMR – A study on the influence of steel reinforcement Read More »

Single-sided NMR devices, like NMR MOUSE (MObile Universal Surface Explorer), are designed to allow NMR surface measurements to be conducted on arbitrarily large samples, and are therefore valuable tools to evaluate non-invasively moisture content “inside” a planar object. In this work, we aim to perform “in situ” studies of moisture transport in building materials during …

Investigation of Drying of Building Materials by Single-sided NMR Read More »

Local increased moisture content (MC) in wood constructions may result in different kinds of mechanical and, especially, biological degrading problems. Therefore, it is of great importance to control the MC of the material. However, there is at present no appropriate method for determining local MC in wood without destroying the product itself. Nondestructive measurements of …

NMR-measurements for determination of local moisture content of coated wood Read More »

The film formation of poly(vinyl alcohol) of different molecular weights from concentrated solution has been observed in real time by means of low-field nuclear magnetic resonance (NMR) methods. The drying of films was followed with a depth resolution of 50 μm up to the formation of the final film of typically 300 μm thickness, and …

Study of the Formation of Poly(vinyl alcohol) Films Read More »

We have evaluated the potential of nuclear magnetic resonance (NMR) spectroscopy based on small portable magnets for in situ assessment of moisture protective properties of wood coatings. Low field 1H NMR with a unilateral permanent magnet was used to monitor and map the local moisture content (MC) of wood specimens uncoated or coated with various types …

Assessment of moisture protective properties of wood coatings by a portable NMR sensor Read More »

The potential to use the NMR‐MOUSE® as non‐destructive analytical tool in building maintenance is demonstrated on two examples. The first one covers moisture transport through fine grained concrete matrices, whereas in the second one the NMR‐MOUSE is used to determine the layer thickness of selected coating systems for concrete protection. In using this NMR technique, …

Application of a mobile NMR sensor as a non‐destructive measurement system in the field of maintenance Read More »

Single-sided magnets give hope that Nuclear Magnetic Resonance (NMR) might in future be used for in situ characterisation of hydration and water transport in the surface layers of concrete slabs. Towards that end, a portable NMR-MOUSE (MObile Universal Surface Explorer) has been used to follow the hydration of gypsum based plaster, a Portland cement paste …

Magnetic Resonance Studies of Cement Based Materials in Inhomogeneous Magnetic Fields Read More »