ANTICORROSION SYSTEMS AND DUCTILE MATERIALS FOR REINFORCED CONCRETE STRUCTURES Dario Rosignoli Tecnochem Italiana S.p.A. Via Sorte 2/4 – 24030 Barzana (Bergamo) - Italy Key words: durability, ductile mortar, chloride barrier, corrosion inhibitors, corrosion current, repair systems Abstract: The main problem concerning the premature failure and the degradation of reinforced concrete (RC) structures is the corrosion of the reinforcement due to chloride contamination of the covercrete. In this contribution recently developed systems for prevention and repair of damaged concrete structures are presented. These systems contain two different technologies: MuCIS which stands for Multiple Corrosion Inhibiting Synergies and HFE-tec which stands for High Fracture Energy Technologies. While corrosion inhibitors which are applied on the surface of corroding reinforced concrete elements have shown little effect the MuCIS system takes advantage of synergies and in this way corrosion can be prevented effectively. Experimental results obtained according to an ASTM test will be presented and they clearly show the effectiveness of the MuCIS system. The efficiency has been verified on more than 8 years period through measurements obtained by the monitoring of a viaduct. HFE-tec involves ductile cement based materials such as SHCC – Strain Hardening Cementitious Composites - and ultra high performance concretes (UHPC). In many seismic areas worldwide there is a strong need of durable and at the same time highly safe reinforced concrete construction and repairs. These materials are suitable for the construction or retrofitting of seismic resistant structures or elements. The 15ο Συνέδριο Σκυροδέματος, ΤΕΕ, ΕΤΕΚ, Αλεξανδρούπολη, 25-27 Οκτωβρίου, 2006 1
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ANTICORROSION SYSTEMS AND DUCTILE MATERIALS FOR REINFORCED CONCRETE STRUCTURES Dario Rosignoli Tecnochem Italiana S.p.A. Via Sorte 2/4 – 24030 Barzana (Bergamo) - Italy
reduced creep and shrinkage high frost resistance aggregates not subjected to alkali-silica reaction
high thermal volumetric stability
chloride barrier carbonation resistance high sulphate resistance reduced water absorption
Table 1: Comparison of the most important properties of the structural concrete and the protective layer
2.2 Realisation of a multifunctional covercrete
For practical realizations, there are at least two different possibilities to
achieve a multifunctional covercrete:
- Impregnation of part of the concrete cover a posterior
- Application of a cement-based coatings
Fig. 3 shows these two different variants for the effective protection of a reinforced
concrete structure.
Figure 1: Possible variants for the practical realisation of a multifunctional covercrete a) impregnation of the covercrete b) application of a cement based coating
with respect to ductility, resistance ion-penetration and anticorrosion function. It is
shown that impregnated concrete cover with MuCIS products and very ductile
mortars (HFE-tec- SHCC) exhibit significantly reduced chloride penetration and
protect the reinforcement from corrosion efficiently. The combined use of these
technologies Multiple Corrosion Inhibiting Synergies and High Fracture Energy
Technologies leads to the realisation of highly durable structures and repairs.
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Durable Reinforced Concrete Structures, In Fifth Workshop on Material Properties and Design, Durable Reinforced Concrete Structures, P. Schwesinger and F. H. Wittmann, (eds).151-160. Freiburg: Aedificatio Publishers.
[3] Gerdes A., Meier S. and Wittmann F. H. 1998. A new application technology for water repellent treatment. In Hydrophobe II. F. H. Wittmann (ed), Water-Repellent Treatment of Building Materials: 217-230. Freiburg: Aedificatio Publishers.
[4] Meier S. und Wittmann F. H. 1999. Notwendige Kriterien für eine Tiefenhydrophobierung, Werkstoffwissenschaften und Bauinstandsetzen. In MSR 99, F. H. Wittmann (ed), 751-762. Freiburg: Aedificatio Publishers.
[5] Sadouki H. and Wittmann F. H. 1998. Influence of water repellent treatment on drying of concrete, In Hydrophobe II. F. H. Wittmann (ed), Water-Repellent Treatment of Building Materials: 177-188 . Freiburg: Aedificatio Publishers.
[6] Martinola G., Sadouki H. and Wittmann F.H. 2001. Numerical model for minimizing the risk of damage in a repair system, Journal of Materials in Civil Engineering, ASCE, Vol. 13 No. 2, 121-129.