Computers and Concrete

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

Spatial dispersion of aggregate in concrete a computer simulation study

  • Hu, Jing (Faculty of Civil Engineering and Geosciences, Delft University of Technology) ;
  • Chen, Huisu (Faculty of Civil Engineering and Geosciences, Delft University of Technology) ;
  • Stroeven, Piet (Faculty of Civil Engineering and Geosciences, Delft University of Technology)
  • Received : 2004.01.01
  • Accepted : 2006.05.01
  • Published : 2006.10.25
⟨ Previous Next ⟩

Abstract

Experimental research revealed that the spatial dispersion of aggregate grains exerts pronounced influences on the mechanical and durability properties of concrete. Therefore, insight into this phenomenon is of paramount importance. Experimental approaches do not provide direct access to three-dimensional spacing information in concrete, however. Contrarily, simulation approaches are mostly deficient in generating packing systems of aggregate grains with sufficient density. This paper therefore employs a dynamic simulation system (with the acronym SPACE), allowing the generation of dense random packing of grains, representative for concrete aggregates. This paper studies by means of SPACE packing structures of aggregates with a Fuller type of size distribution, generally accepted as a suitable approximation for actual aggregate systems. Mean free spacing $\bar{\lambda}$, mean nearest neighbour distance (NND) between grain centres $\bar{\Delta}_3$, and the probability density function of ${\Delta}_3$ are used to characterize the spatial dispersion of aggregate grains in model concretes. Influences on these spacing parameters are studied of volume fraction and the size range of aggregate grains. The values of these descriptors are estimated by means of stereological tools, whereupon the calculation results are compared with measurements. The simulation results indicate that the size range of aggregate grains has a more pronounced influence on the spacing parameters than exerted by the volume fraction of aggregate. At relatively high volume density of aggregates, as met in the present cases, theoretical and experimental values are found quite similar. The mean free spacing is known to be independent of the actual dispersion characteristics (Underwood 1968); it is a structural parameter governed by material composition. Moreover, scatter of the mean free spacing among the serial sections of the model concrete in the simulation study is relatively small, demonstrating the sample size to be representative for composition homogeneity of aggregate grains. The distribution of ${\Delta}_3$ observed in this study is markedly skew, indicating a concentration of relatively small values of ${\Delta}_3$. The estimate of the size of the representative volume element (RVE) for configuration homogeneity based on NND exceeds by one order of magnitude the estimate for structure-insensitive properties. This is in accordance with predictions of Brown (1965) for composition and configuration homogeneity (corresponding to structure-insensitive and structure-sensitive properties) of conglomerates.

Keywords

References

  1. Brown, C.B. (1965), 'Minimum volumes to ensure homogeneity in certain conglomerates', J. Franklin. Inst., 279, 189-199 https://doi.org/10.1016/0016-0032(65)90075-X
  2. Chen, H. (2002), Computer Simulation by SPACE of the Microstructure of the ITZ between Aggregate and Cement Paste, Report CM 2002-001, Delft University of Technology, Delft, The Netherlands
  3. Chen, H. (2003), 'Computer simulation of the microstructure of the Interfacial Transition Zone in Cement-Based Composites', Ph.D. thesis, Southeast University, Nanjing, China (in Chinese)
  4. Cooke, R.W. and Seddon A.E. (1956), 'The laboratory use of bonded-wire electrical resistance strain gauges on concrete at the building research station', Mag. Concrete Res., 8(22)
  5. Diamond, S., Mindess, S. and Lovell, J. (1982), 'On the spacing between aggregate grains in concrete and the dimension of the aureole de transition', Proceedings of Liaisons Pates de Ciment/Materiaux Associes (RILEM publication), Toulouse, 42-46
  6. Freudenthal, A.M. (1950), The Inelastic Behaviour of Engineering Materials and Structures, Wiley, New York
  7. Hu, J. and Stroeven, P. (2003), 'The influence of particle size distribution on the microstructure of model cement', Proceedings of Brittle Matrix Composites 7, Brandt, A.M., Li, V.C. and Marshall, I.H., editors, Poland, 143-152
  8. Jaiswal, S.S., Igusa, T., Styer, T., Karr, A. and Shah, S.P. (1997), 'Influence of microstructure and fracture on the transport properties in cement-based materials', Proceedings of Brittle Matrix Composites 5 (Woodhead publishing, Cambridge), Brandt, A.M., Li, V.C. and Marshall, I.H., editors, Poland, 199-220
  9. Kendall, M.G., Moran, P.A.P. (1963). Geometrical probability, C. Griffin & Co., London
  10. Koenders, E.A.B. (1997), 'Simulation of Volume Changes in Hardening Cement-Based Materials', Ph.D. Thesis, Delft University Press, Delft, The Netherlands
  11. Marchand, J. and Delagrave, A. (1999), 'Influence of ITZ on ionic diffusion and leaching', Engineering and Transport Properties of the Interfacial Transition Zone in Cementitious Composites (RILEM publications), Alexander, M.G., Arliguie, G., Ballivy, G., Bentur, A. and Marchand, J., editors, ENS-Cachan, 157-172
  12. Roeflstra, P. (1989), 'A Numerical Approach to Investigate the Properties of Numerical Concrete', Ph.D. Thesis, EPFL, Lausanne, Switzerland
  13. Scrivener, K.L. and Nemati, K.M. (1995), 'The percolation of pore space in the cement paste/aggregate interfacial zone of concrete', Cement Concrete Res., 26, 35-40 https://doi.org/10.1016/0008-8846(95)00185-9
  14. Stroeven, M. (1999), 'Discrete numerical model for the structural assessment of composite materials', Ph.D. thesis, Delft University of Technology, Delft, The Netherlands
  15. Stroeven, P. (1973), 'Some aspects of the micromechanics of concrete', Ph.D. thesis, Delft University of Technology, Delft, The Netherlands
  16. Stroeven, P. (1974), 'Stereological analysis of structural inhomogeneity and anisotropy of concrete', Proceedings of Quantitative Analysis of Microstructures in Medicine, Biology and Materials Development, Exner, H.E., editor, Special Issues of Practical Metallography, Leoben, Austria, 291-307
  17. Stroeven, P. (2000a), 'Analytical and computer-simulation approaches to the extent of the interfacial transition zone in concrete', Proceedings of Brittle Matrix Composites 6 (Woodhead Publishing ltd., Cambridge), Brandt, A.M., Li, V.C. and Marshall, I.H., editors, Poland, 465-484
  18. Stroeven, P. (2000b), 'A stereological approach to roughness of fracture surfaces and tortuosity of transport paths in concrete', Cement Concrete Comp., 22, 331-341 https://doi.org/10.1016/S0958-9465(00)00018-4
  19. Stroeven, P. and Stroeven, M. (1997), 'Study of crack development as the basis for rheology of cementitious materials', Rheology of Bodies with Defects, IUTAM symposium (Kluwer Academic Publishers, Dordrecht), Wang, R., editor, Beijing, 205-222
  20. Stroeven, P. and Stroeven, M. (1999), 'Assessment of packing characteristics by computer simulation', Cement Concrete Res., 29, 1201-1206 https://doi.org/10.1016/S0008-8846(99)00020-4
  21. Stroeven, P. and Stroeven, M. (2001), 'Size of representative volume element of concrete assessed by quantitative image analysis and computer simulation', Image Analysis & Stereology, 20(suppl. 1), 216-220
  22. Underwood, E.E. (1968), Quantitative Stereology, Addison-Wesley Publishing Company, New Jersey

Cited by

  1. Stochastic heterogeneity as fundamental basis for the design and evaluation of experiments vol.30, pp.6, 2008, https://doi.org/10.1016/j.cemconcomp.2007.12.001
  2. Effects of technological parameters on permeability estimation of partially saturated cement paste by a DEM approach vol.84, 2017, https://doi.org/10.1016/j.cemconcomp.2017.09.013
  3. Theoretical prediction on thickness distribution of cement paste among neighboring aggregates in concrete vol.8, pp.2, 2011, https://doi.org/10.12989/cac.2011.8.2.163
  4. Stochastic Development Model for Compressive Strength of Fly Ash High-Strength Concrete vol.33, pp.12, 2021, https://doi.org/10.1061/(asce)mt.1943-5533.0003998