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This paper presents a proof of concept for monitoring masonry structures using two different types of markers which are not easily noticeable by human eye but exhibit high reflection when subjected to NIR (near-infrared) wavelength of light. The first type is a retroreflective marker covered by a special tape that is opaque in visible light but translucent in NIR, while the second marker is a paint produced from infrared reflective pigments. The reflection of these markers is captured by a special camera-flash combination and processed using image processing algorithms. A series of experiments were conducted to verify their potential to monitor crack development. It is shown that the difference between the actual crack width and the measured was satisfactorily small. Besides that, the painted markers perform better than the tape markers both in terms of accuracy and precision, while their accuracy could be in the range of 0.05 mm which verifies its potential to be used for measuring cracks in masonry walls or plastered and painted masonry surfaces. The proposed method can be particularly useful for heritage structures, and especially for acute problems like foundation settlement. Another advantage of the method is that it has been designed to be used by non-technical people, so that citizen involvement is also possible in collecting data from the field.

This paper aims to quantify the evolution of damage in masonry walls under induced seismicity. A damage index equation, which is a function of the evolution of shear slippage and opening of the mortar joints, as well as of the drift ratio of masonry walls, was proposed herein. Initially, a dataset of experimental tests from in-plane quasi-static and cyclic tests on masonry walls was considered. The experimentally obtained crack patterns were investigated and their correlation with damage propagation was studied. Using a software based on the Distinct Element Method, a numerical model was developed and validated against full-scale experimental tests obtained from the literature. Wall panels representing common typologies of house façades of unreinforced masonry buildings in Northern Europe i.e. near the Groningen gas field in the Netherlands, were numerically investigated. The accumulated damage within the seismic response of the masonry walls was investigated by means of representative harmonic load excitations and an incremental dynamic analysis based on induced seismicity records from Groningen region. The ability of this index to capture different damage situations is demonstrated. The proposed methodology could also be applied to quantify damage and accumulation in masonry during strong earthquakes and aftershocks too. The work presented in this paper is supported by the – Seismic Monitoring, Design and Strengthening For thE GrOningen Region, Project number: RAAK.MKB09.021.

Sinds tien jaar zorgen bastscheuren voor veel problemen in de laanbomensector. Over de oorzaken wordt steeds meer bekend. PPO Boomkwekerij heeft onderzoek gedaan naar bastscheuren en presenteert de resultaten

Naar aanleiding van grote problemen in 2006 met bastschade door zonnebrand bij laanbomen is in de periode 2008 – 2011 onderzoek gedaan om hiervoor een oplossing te vinden. Door PPO is een literatuurstudie uitgevoerd en zijn uiteenlopende beschikbare beschermmaterialen in een veldproef getest. In de veldproef is zoveel mogelijk rekening gehouden met omstandigheden die de kans op zonnebrand zouden kunnen bevorderen.

Naar aanleiding van grote problemen in 2006 met bastschade door zonnebrand bij laanbomen is in de periode 2008 – 2011 onderzoek gedaan om hiervoor een oplossing te vinden. Door PPO is een literatuurstudie uitgevoerd en zijn uiteenlopende beschikbare beschermmaterialen in een veldproef getest. In de veldproef is zoveel mogelijk rekening gehouden met omstandigheden die de kans op zonnebrand zouden kunnen bevorderen.

Sinds tien jaar zorgen bastscheuren voor veel problemen in de laanbomensector. Over de oorzaken wordt steeds meer bekend. PPO Boomkwekerij heeft onderzoek gedaan naar bastscheuren en presenteert de resultaten

This report addresses the results of an experiment with field trials with potatoes and silage maize onsandy soil in 2006 in order to obtain a suitable indicator for predicting N-mineralisation after ploughing the grassland. This study is part of a larger project with more field trials and a laboratory experiment. Ploughed grassland on the locations selected provided much nitrogen, due to which it was not possible to infer an indicator from the crop response for adjusting nitrogen recommendation. N-total seems to be the most promising parameter in predicting nitrogen mineralisation

This report addresses the results of an experiment with field trials with potatoes and silage maize onsandy soil in 2006 in order to obtain a suitable indicator for predicting N-mineralisation after ploughing the grassland. This study is part of a larger project with more field trials and a laboratory experiment. Ploughed grassland on the locations selected provided much nitrogen, due to which it was not possible to infer an indicator from the crop response for adjusting nitrogen recommendation. N-total seems to be the most promising parameter in predicting nitrogen mineralisation In dit rapport wordt ingegaan op de resultaten van onderzoek met veldproeven naar een geschikte indicator om de N-mineralisatie na het scheuren van grasland te voorspellen met aardappelen en snijmaïs op zandgrond in 2006. Dit onderzoek maakt deel uit van een groter project met meer veldproeven en een labstudie. Het gescheurde grasland op de gekozen locaties leverde veel stikstof. Hierdoor was het niet mogelijk om op basis van gewasrespons een indicator voor bijstelling van het stikstofadvies af te leiden. N-totaal lijkt het meeste perspectief te bieden voor de voorspelling van de stikstofmineralisatie