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Liu Q.,Technical University of Delft | Schlangen E.,Technical University of Delft | van de Ven M.F.C.,Technical University of Delft | van Bochove G.,Heijmans | van Montfort J.,SGS Intron
RILEM Bookseries

The induction healing concept of porous asphalt was developed at Delft University of Technology and was proven very successful in the laboratory. A porous asphalt test section with this self healing concept was also paved on Dutch highway A58. This special porous asphalt contained 4% steel wool (by volume of bitumen). A number of cores were drilled from this test section to predict its performance. Beams were also prepared with the same materials as used in the test section. Experiments were done on these specimens to study the mechanical, heating and healing properties. It is found in Cantabro test that the particle loss resistance of porous asphalt concrete is improved by addition of steel wool. The improvement in particle loss resistance will delay ravelling on the pavement. It is also proven that the cores containing steel wool can be heated quickly with induction energy. Finally, it is found that the fatigue life of the beamsis extended greatly by applying induction heating during the rest period. The damage (cracking) in the porous asphalt beams ishealed by induction healing. Based on these findings, it is concluded that the life time of the test section will be extended by the reinforcement of steel wool and induction heating. © RILEM 2012. Source

Liu Q.,Technical University of Delft | Schlangen E.,Technical University of Delft | Van De Ven M.,Technical University of Delft | Van Bochove G.,Heijmans | Van Montfort J.,SGS Intron
Construction and Building Materials

The objective of this paper is to evaluate the induction healing effect of steel wool reinforced porous asphalt concrete. The four point bending fatigue resistance of the beams was first studied. It was found that the fatigue resistance of these steel wool reinforced beams was quite good compared with the references in the literature. Then, fatigue life extension ratio and flexural stiffness recovery of the beams were used to show their healing effect. The fatigue life extension ratio was measured after introducing induction heating and letting the fatigue damaged beams rest. It was found that induction heating increases the healing rate of the beams and that the healing is highly microstrain-dependent with higher healing rate under high microstrain level. It was also found that the optimal heating temperature is 85 °C to obtain the best healing effect. Heating too much can cause swelling in the specimens, which will decrease the total healing produced. The fatigue damaged beams obtained extra stiffness recovery when induction heating was applied to them. Finally, it was also found that fatigue life of porous asphalt concrete can be significantly extended by applying multiple induction heating. Based on these findings, it is concluded that the self healing effect of porous asphalt concrete can be increased by induction heating the material. Additionally, the durability of porous asphalt pavement will also be improved with induction healing. © 2011 Elsevier Ltd. All rights reserved. Source

Mans D.-G.,Meged Eng.and Consultancy | De Jonker M.,SGS Intron | Wijte S.,Adviesbureau Hageman
Engineering for Progress, Nature and People

This paper reports about the structural safety of cantilevered reinforced concrete balconies of apartment buildings in the Netherlands. The concrete floor of this type of balconies is between 80 mm and 150 mm thick. This type of balconies was mainly constructed between 1950 and 1970. After a collapse of a balcony situated at the 9th floor level of an apartment building, investigations started to the causes. Pit corrosion of the reinforcement, induced by chlorides, had reduced the cross section of reinforcement steel. Besides that, the position of the reinforcement was 10% lower as prescribed in the design and the permanent loads were 28% higher as assumed in the design. As follow up, the structural safety of another eleven buildings with similar balcony structures were assessed. In six of the eleven buildings measures related to structural safety had to be taken. It was clear that owners of this type of building in the Netherlands need to assess the risk of lack of structural safety. To promote an efficient assessment of the structural safety, a step by step method was developed. In the step by step method three specific risks are evaluated: pit corrosion, a lower position of the reinforcement as described in the design and higher permanent loads as assumed in the design. For the assessment of existing structures, lower partial safety factors are used. With drawings and calculations of the structure and the results of non-destructive tests a first check of the structural safety can be done. After that, the sensitivity of the structure to cracks and corrosion of the reinforcement are estimated. If the sensibility is low, further investigations are postponed, if not further investigation into the presence of chlorides and corrosion rate is necessary. The assessment ends with a conclusion: the structural safety meets the requirements or measures have to be taken. Source

De Block M.,SGS Horizon | Hofmann A.,SGS Horizon | Rigollet C.,SGS Horizon | Portier E.,GDF SUEZ | And 3 more authors.
6th Saint Petersburg International Conference and Exhibition on Geosciences 2014: Investing in the Future

Methods for determining properties of shales from cuttings samples are beneficial as they provide a fast and cost-efficient way for evaluating potential shale reservoirs for which often core sample data and modern wireline logs are missing. A case study is performed on 80 cuttings samples from the radioactive Silurian shales of a Palaeozoic basin in SW Algeria. In this study geochemical (Rock-Eval pyrolysis and LECO carbon analysis), mineralogical (QEMSCAN analysis), structural (CT scanning) and geomechanical (nanoindentation) analyses are performed on cuttings samples to characterize the heterogeneity of the shales and predict shale gas sweet spots. Using these innovative analysis methods reliable values for the properties of the radioactive Silurian shales are obtained. By integrating TOC content values and QEMSCAN data with wireline logs, clear vertical trends/cycles are identified and the strong vertical and lateral heterogeneity of the shales is demonstrated. Using CT scanning different fractural networks are observed and Young's modulus values obtained from nanoindentation measurements are in the range expected for shales (± 33 GPa) and are appropriate for shale gas production. The shale gas opportunity is confirmed for the radioactive Silurian shales and sweet spots are indicated by high TOC contents and favorable mineralogical compositions and geomechanical properties. Copyright © 2014 by the European Association of Geoscientists & Engineers. All rights reserved. Source

Van Dr Wegen G.,SGS Intron | Hofstra U.,SGS Intron | Speerstra J.,SGS Intron
Waste and Biomass Valorization

The objective of this research was to examine the technical feasibility of upgraded bottom ash from municipal solid waste incinerators as fine and coarse aggregate in concrete. The effect of partial replacement of natural sand and gravel by such bottom ash on all relevant properties of concrete (technological, structural as well as durability and reuse as recycled aggregate) has been determined. Based on these findings a guideline has been formulated for the use of upgraded incinerator bottom ash in ready-mixed as well as precast concrete. Although the upgraded bottom ash is of better quality then the original bottom ash, some properties still need special attention (i.e. must meet additional requirements): particle density, metallic aluminium content, loss on ignition, chloride, sulphate and alkali content and, finally, constituents which alter the setting and hardening of the cement. Upgraded incinerator bottom ash can replace up to 20 %V/V sand and/or gravel in reinforced concrete and up to 50 %V/V in plain concrete (non-structural concrete). Application in prestressed concrete is not recommended because of the possibly higher risk of stress corrosion in the prestressed steel. © Springer Science+Business Media Dordrecht 2013. Source

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