Piet Stroeven's Books

Brittle Matrix Composites

Porosity of green concrete based on a gap-graded blend

By: Nghi L.B. Le,Piet Stroeven

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Brittle Matrix Composites

Porosity of green concrete based on a gap-graded blend

By: Nghi L.B. Le,Piet Stroeven

Portland cement (PC) production contributes by about 6% to global emissions of C02. Reduction of the PC content in the binder exerts therefore a direct positive effect on such emissions. Partial replacement of the Portland cement by pozzolanic mineral admixtures has been proven a possible option. The green character is even reinforced by making use of incinerated vegetable waste, such as rice husk ash (RHA). Moreover, as a result of the gap-grading effect on particle packing density with RHA as the fine component, high strength concrete can be achieved with RHA-blended cement. This has been published earlier, so the paper only briefly covers these aspects. Characteristics of the capillary pores developed in the hydrating binder have direct impact on the transport-based durability properties. However, assessment of such pore characteristics of the RHA-blended cement constitutes a complicated problem, especially in experimental approaches. This paper, therefore, presents a new economic approach to conduct such investigation on the realistically produced cementitious materials in virtual reality. The fresh packed state of the paste’s particles is simulated by a discrete element modeling (DEM) system, HADES. The hydration of a (blended) cement is simulated by a so-called ‘extended integrated particle kinetics model’ (XIPKM). Pore characteristics, such as topology, location distribution, degree of percolation and fraction of main channels in the pore network, are explored by a new modern approach named ‘double random multi-tree structuring’ (DraMuTS). The size distribution of throats that significantly limit the transport in the pore network system is derived from star volume measurements. Four examples of plain PC and of RHA-blended PC with two w/b ratios are presented. The expected positive effects on transport-based durability issues due to RHA-blending are discussed.

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ISBN 10

0128090391

ISBN 13

9780128090398

Brittle Matrix Composites

Durability of cellulose-cement composites assessed by accelerated testing under temperature and moisture variations - effects of blending by rice husk ash

By: Conrado de Souza Rodrigues,Mariana Arruda Pereira,Stefan Chaves Figueiredo,Khosrow Ghavami,Piet Stroeven

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Brittle Matrix Composites

Durability of cellulose-cement composites assessed by accelerated testing under temperature and moisture variations - effects of blending by rice husk ash

By: Conrado de Souza Rodrigues,Mariana Arruda Pereira,Stefan Chaves Figueiredo,Khosrow Ghavami,Piet Stroeven

More recent investigations on cellulose-cement composites predominantly deal with durability aspects, whereby use is made of accelerated weathering cycles as the main approach to establishing the deterioration mechanisms and the efficiency of treatment methods. As moisture transport is the main mechanism that leads to the deterioration of those composites, accelerated ageing tests are commonly based on wet-drying cycles with a combination of temperature and relative humidity (R.H.) variations. Both variables result in dimensional changes of the samples, leading to interfacial abrasion and the progressive decrease in the composites’ toughness and strength. To investigate the effects of each of these variables, the weathering tests were performed in an environmental chamber considering each variable separately in two ageing cycles. In the first one the composites were submitted to saturation and drying at a constant 25°C, by means of a relative humidity change in the chamber. For the second ageing cycle a temperature variation between 20°C and 60°C at a constant R.H. of 50% was applied. The effects of each ageing cycle on the cellulose-cement composites were assessed on the basis of physical and mechanical parameters, determined after 0, 5, 20 and 50 cycles. Moreover, part of the samples was provided with electrical strain gauges, which rendered possible to determine the composites’ expansion-shrinkage behaviour during the temperature and R.H. variations. As the main treatment approach, the partial replacement of cement (OPC) by rice husk ash (RHA) was investigated. It was found that RHA improved the strength and durability performance of the composites, although the increased porosity resulted from the 30% replacement rate of OPC and carbonate filler by RHA.

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Elsevier Inc. Chapters

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ISBN 10

0128090464

ISBN 13

9780128090466

Brittle Matrix Composites

Assessment of pore characteristics in virtual concrete by path planning methodology

By: Piet Stroeven,Lambertus J Sluys,Nghi L.B. Le

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Brittle Matrix Composites

Assessment of pore characteristics in virtual concrete by path planning methodology

By: Piet Stroeven,Lambertus J Sluys,Nghi L.B. Le

This paper will discuss novel techniques for pore network exploration and the assessment of topological and geometrical characteristics relevant for durability estimation. The discussed methods are applicable to DEM-produced cementitious materials in which binder particle are realistically dispersed. This cannot be achieved by the in concrete technology popular random generator-based systems. Development of the discussed techniques was inspired by the path finding algorithms developed in robotics. The presented techniques are called double random multiple tree structuring (DraMuTS) and random node structuring (RaNoS). The path finding algorithms are adapted to the porosimetry problem and as a consequence modified to exclude time-consuming iterations. Moreover, path finding will take place starting from a large number of positions to enhance the economy of the approach.

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ISBN 10

0128090286

ISBN 13

9780128090282

Brittle Matrix Composites

Shape simulation of granular particles in concrete and applications in DEM

By: Huan He,Piet Stroeven,Eric Pirard,Luc Courard

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Brittle Matrix Composites

Shape simulation of granular particles in concrete and applications in DEM

By: Huan He,Piet Stroeven,Eric Pirard,Luc Courard

Aggregate occupies at least three-quarters of the volume of concrete, so its impact on concrete’s properties is large. The sieve curve traditionally defines the aggregate size range. Another essential property is grain shape. Both, size and shape influence workability and the mechanical and durability properties of concrete. On the other hand, the shape of cement particles plays also an important role in the hydration process due to surface dissolution in the hardening process. Additionally, grain dispersion, shape and size govern the pore percolation process that is of crucial importance for concrete durability Discrete element modeling (DEM) is commonly employed for simulation of concrete structure. To be able doing so, the assessed grain shape should be implemented. The approaches for aggregate and cement structure simulation by a concurrent algorithm-based DEM system are discussed in this paper. Both aggregate and cement were experimentally analyzed by X-ray tomography method recently. The results provide a real experimental database, e.g. surface area versus volume distribution, for simulation of particles in concrete technology. Optimum solutions are obtained by different simplified shapes proposed for aggregate and cement, respectively. In this way, reliable concepts for aggregate structure and fresh cement paste can be simulated by a DEM system.

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ISBN 10

0128090359

ISBN 13

9780128090350

Book's by Piet Stroeven

Brittle Matrix Composites

Brittle Matrix Composites

Brittle Matrix Composites

Brittle Matrix Composites

Brittle Matrix Composites

Brittle Matrix Composites

Brittle Matrix Composites

Brittle Matrix Composites

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