Engineering Mechanics Institute Conference 2013

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Permeability properties of in site concrete supply

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Francesca Giussani
Politecnico di Milano
Italy

S. Cattaneo
Politecnico di Milano
Italy

Abstract:
The relevant expenses caused by problems related to durability of reinforced concrete structures have increased the researches covering the production of better and more durable concretes over the last few decades. Since damages in concrete structures are often connected to corrosion of reinforcement, the life time is often evaluated by checking the penetration of fluids into concrete. Durability is hence strictly related to permeability, since the water that penetrates into concrete generally contains soluble salts including chloride ions which cause corrosion of rebars. Nevertheless, permeability characteristics of concrete appear to be rather difficult to predict, even knowing the mix design.
Furthermore, some literature can be found on permeability laboratory tests on ad hoc specimens, but very few researchers considered specimens casted on site. For this reason, the authors have collected results of more than 1300 permeability tests on in site casted concretes performed from 2010 till now at Politecnico di Milano and have analysed the results obtained.
Concrete specimens from more than 100 construction sites were collected and their permeability properties were determined by measuring the depth of penetration of water under pressure, according to the European Standard EN 12390-8 (2009) .
The results have shown that
- Permeability is slightly connected to tensile strength (Figure 1), while no relation exists with density.
- Permeability slightly increase by increasing the water/cement ratio.
- Permeability is significantly related to the aggregate distribution: limiting the maximum size of aggregates leads to reduced water permeation (FigureĀ°2).

 

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