Summary of the technology
The main system innovation is the use of ion conductive gels as reservoirs of chlorides in migration assays. Until now the techniques had to start with the full saturation of the specimen and keeping it in contact with a chloride ions solution during diffusion or migration tests. This guaranteed the absence of other transport mechanisms (such as capillary absorption) and avoided surface moisture changes. This new method is simple to implement and allows the elimination of these requirements.
Another innovative feature is that the system allows greater measuring accuracy of the advancing chloride front, because this advance occurs more homogeneously than in conventional tests in contact with liquid solutions.
Description of the technology
Researchers of the University of Alicante have developed a new method to assess the durability of reinforced concrete. The parameter used is the diffusion coefficient of chloride ions, which is related to the transport speed of chloride ions through the concrete, and therefore the time it takes triggered embedded steel corrosion. This test requires saturated samples of concrete. University researchers have developed a method to perform this test in a non-saturated medium, using conductive gels as chloride reservoirs. The main advantage of this technology is the elimination of the liquid environments for testing, thus eliminating the medium saturation restriction. This allows determining the diffusion coefficient in partial water saturation states of the concrete.
Researchers of the Civil Engineering Department at the University of Alicante have developed a new method to overcome the restrictions of these techniques in terms of the requirements for concrete moisture. The proposed method provides the use of two conductive gels in each side of the concrete specimen. The first conductive gel is a gel consisting of a matrix with Cl- ions (NaCl for example) and a binder compound. This gel is in contact with one face of the concrete test specimen, and is connected through an electrode to the negative pole of a power source. The second conductive gel is a gel similar to the above mentioned and with the same ionic conductivity, but formed by a free Cl- matrix ions (NaNO3 for example). This gel is placed on the opposite side of the specimen and is connected through a second electrode to the positive pole of the power source. By connecting the power source, anions contained in the gel NaCl are forced to pass through the concrete being tested, obtaining an appropriate chloride profile to set the migration coefficient of concrete.
Main advantages of its use
- One of the electrodes can be replaced by one of the steel bars embedded in the concrete for the implementation of the method in real structures or samples.
- Prevention of sealing problems deriving from the use of liquid solutions.
- The main advantage of this technology is that it avoids the concrete saturation requirement for the concrete durability tests.
- The use of conductive gels is not a significant additional cost.
- This method can work in a less restrictive and closer to reality medium.Ensures a better definition on the advancing front edge, ensuring good measurement accuracy.
- This technology is of interest to various companies in the building industry as concrete manufacturers, material testing laboratories, construction, architecture, etc.