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Magalhaes Pereira, L.F. (author), Weerheijm, J. (author), Sluys, L.J. (author)
The development of realistic numerical tools to efficiently model the response of concrete structures subjected to close-in detonations and high velocity impacts has been one of the major quests in defense research. Under these loading conditions, quasi-brittle materials undergo a multitude of failure (damage) mechanisms. Dynamic tensile failure...
conference paper 2015
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Palin, D. (author), Thijssen, A. (author), Wiktor, V. (author), Jonkers, H.M. (author), Schlangen, H.E.J.G. (author)
Ordinary Portland cement (OPC) mortar specimens submerged in sea-water were analysed through environmental scanning electron microscopy (ESEM) in back scattered electron (BSE) mode and nano-scratching. Results from both sets of analysis show the presence of distinct phases associated with aragonite, brucite and cement paste. Phases associated...
conference paper 2015
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Slobbe, A.T. (author), Hendriks, M.A.N. (author), Rots, J.G. (author)
This paper presents a dedicated numerical test that enables to assess the directional mesh bias of constitutive models in a systematic way. The test makes use of periodic boundary conditions, by which strain localization can be analyzed for different mesh alignments with preservation of mesh uniformity and with exclusion of boundary disturbances...
conference paper 2013
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Wiktor, V.A.C. (author), Jonkers, H.M. (author)
This paper focuses particularly on the ageing of concrete due to micro-crack formation or freeze/thaw which results in an increased permeability of the concrete. The bacteria-based repair system presented in this paper aims at recovering the concrete permeability thanks to bacteria-induced calcium carbonate precipitation inside cracks/porosity....
conference paper 2014
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Mors, R.M. (author), Jonkers, H.M. (author)
conference paper 2015
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Mors, R.M. (author), Jonkers, H.M. (author)
A functional experimental concrete system has been developed in our lab, in which a two component bacteria-based healing agent contained in a protective reservoir is included in the concrete mixture. Incorporated bacteria have the potential to produce copious amounts of calcium carbonate based crystals from supplied mineral precursor compounds....
conference paper 2013
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Stroeven, P. (author), He, H. (author)
Loose random and dense random mono-size pacl<ing states were investigated by the discrete element modelling (DEM) for eight types of polyhedral grains, for ellipses with different aspect ratio, for cubes and for spheres. Focus was on density, sphericity of the grains and average value and frequency distribution of coordination number. The 3D...
conference paper 2013
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Sierra Beltran, M.G. (author), Jonkers, H.M. (author), Mors, R.M. (author), Mera-Ortiz, W. (author)
This paper describes the first field application of self-healing concrete with alkaliphilic spore-forming bacteria and reinforced with natural fibres. The application took place in the highlands in Ecuador in July 2014. The concrete was cast as linings for an irrigation canal that transports water from glaciers in the Andean mountains to...
conference paper 2015
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Stroeven, P. (author), Le, N.L.B. (author), Stroeven, M. (author), Sluys, L.J. (author)
The paper introduces a novel approach to porosimetry in virtual concrete, denoted as random node structuring (RNS). The fresh state of this particulate material is produced by the DEM system HADES. Hydration simulation is a hybrid approach making use of wellknown discretization and vector methods. Particle interferences (overlap) in the dynamic...
conference paper 2011
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Rots, J.G. (author), Invernizzi, S. (author), Belleti, B. (author), Hendriks, M.A.N. (author)
conference paper 2009
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Zemskov, S.V. (author), Copuroglu, O. (author), Vermolen, F.J. (author)
A mathematical model for the post-damage recovery of carbonated cement is described. The model is based on a two-dimensional initial-boundary value problem for a system of partial differential equations. The study is embedded within the framework of investigating the effect of using lightweight expanded clay aggregate, which is incorporated into...
conference paper 2013
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Nguyen, V.P. (author), Stroeven, M. (author), Sluys, L.J. (author)
In this contribution, we present the mechanical behaviour of the hardening cement paste explicitly taking into account its complex microstructure. The microstructure of the cement paste is obtained via numerical cement hydration simulation. A simple nonlocal isotropic damage model is adopted for different constituents of the cement paste. The...
conference paper 2009
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Savija, B. (author), Schlangen, E. (author)
Concrete structures are commonly cracked when in service. To overcome issues arising from cracking, self-healing concrete is being developed. Together with the development of the material, techniques to verify and quantify self-healing are being developed. A number of destructive techniques have been used in the past. It would be beneficial to...
conference paper 2015
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Wiktor, V.A.C. (author), Jonkers, H.M. (author)
conference paper 2011
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Weerheijm, J. (author), Sharma, A. (author), Ozbolt, J. (author)
The behavior of concrete structures is strongly influenced by the loading rate. Compared to quasi-static loading, on meso and macro-scale concrete loaded by impact loading acts in a different way. First, there is a strain-rate influence on strength, stiffness, ductility, and, second, there are inertia forces activated which influence the...
conference paper 2013
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Bonifazi, G. (author), Capobianco, G. (author), Serranti, S. (author), Eggimann, M. (author), Wagner, E. (author), Di Maio, F. (author), Lotfi, S. (author)
Aim of this work was to investigate the microstructure of the Interfacial Transition Zone (ITZ) between cement paste and aggregate in concrete utilizing Scanning Electron Microscope (SEM) in order to identify possible effects on the ITZ related to different recipes and production parameters. SEM is an important tool to carry out concrete, cement...
conference paper 2015
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Pradena, M. (author), Houben, L.J.M. (author)
Concrete pavements (CPs) are durable and they do not need periodic invasive maintenance interventions. Nevertheless, CPs are hardly chosen when only initial costs, instead of life-cycle costs, are considered in the evaluation. Nowadays, there are innovations in Jointed Plain Concrete Pavements (JPCPs) that reduce initial costs about 25% with...
conference paper 2014
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Wiktor, V. (author), Jonkers, H.M. (author)
Biodeposition, a method by which calcium carbonate (CaCO3) precipitation is induced by bacteria, has been proposed as an interesting approach to protect building materials. The liquid-based system presented in this paper aims at the sealing of cracks and decrease of the porosity due to the production of a calcium-based biomineral. In this system...
conference paper 2015
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Sangadji, S. (author), Wiktor, V.A.C. (author), Jonkers, H.M. (author), Schlangen, H.E.J.G. (author)
Bacteria induced calcite precipitation has been proven to be effective in making concrete structure self-healing. In Microlab TU Delft, the concept has been enhanced by developing a liquid bacteria-based concrete repair system. The solution contains calcite precipitating bacteria, nutrients and buffer compound which may demonstrate high...
conference paper 2013
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Grünewald, S. (author), Janssen, B. (author), Schipper, H.R. (author), Vollers, K.J. (author), Walraven, J.C. (author)
This paper discusses the effect of intentional deformation of a flexible formwork after casting of the concrete and the influence of the characteristics of concrete in the fresh state on the quality of a concrete element. This deformation is intended to bring the concrete element in its desired final shape; the deformation typically takes place...
conference paper 2012
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