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A platform for research: civil engineering, architecture and urbanism
Concrete protection via internal hydrophobization
Due to a wide variety of environmental impacts like water and chloride ingress, concrete structures show a limited lifetime. The main origin for deterioration of porous mineral substrates is the transport of water dissolved pollutants via capillary force. Depending on the load with pollutants, e.g. chlorides from deicing salts, it is sometimes necessary to carry out expensive repair work severalfold within the lifetime of a concrete structure. It is well known that a treatment with monomeric alkyl alkoxy silanes leads to a prolonged service life if the work (hydrophobic treatment) is accomplished professional. Unfortunately hydrophobic treatment is an additional step in the sequence of work steps within a restoration or erecting of a new building, which is connected with sometimes intolerable effort. On the one hand 28 days curing time of the cement based building material is recommended prior to a hydrophobic treatment, on the other hand an area-wide quality control, e.g. via detection of penetration depth, is very expensive and practically unfeasible. These disadvantages are avoidable, if alkyl alkoxy silanes could be used as an additive in the concrete mix. It is known that water based alkyl trialkoxy silane emulsions, which are stable under alkaline conditions, are suitable additives in the concrete mix, leading to an excellent reduction of water and chloride uptake. This process, called integral hydrophobization, is actually seldom used in practice. Only limited experience with this attractive new concept does exist. It is mentioned in the literature, that silane emulsions affect the rheolocical behaviour of the concrete mix and lower the strength of the cured concrete. The present article shows, that in practice integral hydrophobic treatment is easily controllable with an appropriate concrete mix design. A case study - the restoration of a parking garage in Switzerland, which was heavily affected by chloride corrosion - shows the successful application of a silane emulsion as an additive in the concrete mix, which leads to perfect reduction of water uptake, perfect adhesion of the covercrete to the old concrete, and excellent compressive strength.
Concrete protection via internal hydrophobization
Due to a wide variety of environmental impacts like water and chloride ingress, concrete structures show a limited lifetime. The main origin for deterioration of porous mineral substrates is the transport of water dissolved pollutants via capillary force. Depending on the load with pollutants, e.g. chlorides from deicing salts, it is sometimes necessary to carry out expensive repair work severalfold within the lifetime of a concrete structure. It is well known that a treatment with monomeric alkyl alkoxy silanes leads to a prolonged service life if the work (hydrophobic treatment) is accomplished professional. Unfortunately hydrophobic treatment is an additional step in the sequence of work steps within a restoration or erecting of a new building, which is connected with sometimes intolerable effort. On the one hand 28 days curing time of the cement based building material is recommended prior to a hydrophobic treatment, on the other hand an area-wide quality control, e.g. via detection of penetration depth, is very expensive and practically unfeasible. These disadvantages are avoidable, if alkyl alkoxy silanes could be used as an additive in the concrete mix. It is known that water based alkyl trialkoxy silane emulsions, which are stable under alkaline conditions, are suitable additives in the concrete mix, leading to an excellent reduction of water and chloride uptake. This process, called integral hydrophobization, is actually seldom used in practice. Only limited experience with this attractive new concept does exist. It is mentioned in the literature, that silane emulsions affect the rheolocical behaviour of the concrete mix and lower the strength of the cured concrete. The present article shows, that in practice integral hydrophobic treatment is easily controllable with an appropriate concrete mix design. A case study - the restoration of a parking garage in Switzerland, which was heavily affected by chloride corrosion - shows the successful application of a silane emulsion as an additive in the concrete mix, which leads to perfect reduction of water uptake, perfect adhesion of the covercrete to the old concrete, and excellent compressive strength.
Concrete protection via internal hydrophobization
Standke, B. (author) / Schafroth, Rene (author) / Germann, A. (author)
2003
8 Seiten, 6 Bilder, 11 Quellen
Conference paper
English
Concrete Protection via Internal Hydrophobization
| British Library Conference Proceedings | 2003