Characterization and modelling of previous concrete
Pervious concrete is a special material with high permeability usually obtained by reducing the amount of fine aggregates in the composition of concrete. The properties of pervious concrete not only depend on its composition but also on the construction methods. The compaction process has a direct i...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/393943 |
| Acceso en línea: | http://hdl.handle.net/10803/393943 https://dx.doi.org/10.5821/dissertation-2117-96338 |
| Access Level: | acceso abierto |
| Palabra clave: | Àrees temàtiques de la UPC::Edificació 004 620 69 |
| Sumario: | Pervious concrete is a special material with high permeability usually obtained by reducing the amount of fine aggregates in the composition of concrete. The properties of pervious concrete not only depend on its composition but also on the construction methods. The compaction process has a direct influence on the values of permeability and mechanical properties achieved. In fact, depending on the level of compaction applied, the same composition might give a highly pervious or even an almost impervious concrete. The interest of the scientific and technical community about pervious concrete has increased significantly since the 90's. Despite the technological advances on this field, the definition of the most adequate composition and compaction process to comply with the requirements of each application is normally based on trial and error or previous experiences. The lack of composition design methods in the literature may be attributed to the high complexity of the factors that intervene in the final performance of pervious concrete, which may hardly be generalized for all practical situations. In this context, the objective of this PhD thesis is to achieve a deeper understanding about pervious concrete and promote a new composition design philosophy based on advanced numerical simulations to minimize the need of experimental tests. This work covers the main aspects of production and performance of pervious concrete, from the fresh to the hardened state. The first subject refers to the compaction process in the fresh state. An Evolutionary Lattice Model is developed for simplified 2D simulations. As a more realistic alternative, new constitutive laws are developed and implemented in Discrete Element Models for 3D simulations. To validate these models, experimental programs that emulate a controlled compaction were performed. The results confirm the representativeness of the models developed. The second subject focuses on the permeability of concrete in the hardened state. The meso-structure derived from 3D simulations of the compaction process in the previous subject are evaluated in terms of their permeability. Computational Fluid Dynamics models are used to simulate the water flow through the material. An experimental program is conducted with a constant head permeameter and different types of pervious concrete. The results obtained are used to validate the numerical models, confirming that it is possible to reproduce the real permeability results based on combined numerical simulations of the compaction process and of the water flow within the material. The third subject is centred on the mechanical properties of pervious concrete in the hardened state. A new constitutive law is developed and implemented in DEM to simulate the interaction between the connected particles that form the material. The meso-structure obtained as a result of the compaction simulations are used to assess numerically the expected mechanical properties of the pervious concrete. An experimental program is conducted to evaluate the compressive and indirect tensile strength of pervious concrete with different compositions and subjected to several degrees of compaction. The numerical results estimated with this constitutive law together with the meso-structure show good agreement with the experimental results. The studies conducted in this work confirm that it is also possible to predict the performance expected in reality. Consequently, the numerical tools might be used to accelerate the process of defining the concrete composition and the production process for each application. |
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