REPAIRING CONCRETE OUR COMPLETE RANGE OF SOLUTIONS

Transcription

1 REPAIRING CONCRETE OUR COMPLETE RANGE OF SOLUTIONS

2 WHY IS IT IMPORTANT TO CONSOLIDATE REINFORCED CONCRETE STRUCTURES? 5 KEY REASONS To restore load bearing capacity, in the event of accidental impacts, reinforcement corrosion or after a fire. To locally reinforce construction elements, e.g. drilling of concrete slabs or shells (shaft openings, crossheads,...). To increase the load bearing capacity of construction elements whose initial purpose may have been modified. The proportioning of reinforcement elements, and in particular the crosssection, the length and the position of reinforcement or carbon composite must be performed by a Design and Engineering specialist with experience of performing structural reinforcement calculations. Application must solely be performed by specialized, qualified firms whose employees have received training in the appropriate application techniques and who are backed up by technical assistance from the manufacturer. Such firms must be able to provide a list of previous references for the relevant procedures. For positioning and control purposes, the specialist firm must refer to information provided in ATEX No To repair construction errors. To provide added protection in aggressive environments not foreseen at the design stage.

3 WHY DO STEEL REBARS BECOME CORRODED? Concrete is a non-homogenous material, a subtle blend of cement, aggregates, water and admixtures. It is a living material, subject to attack from severe weather and the day-today aggressions of modern life. Damage caused by rebar corrosion accounts for 80% of all concrete problems encountered. ATMOSPHERE Oxygen Cl - H 2 O Steel rebar corrosion is the result of a combination of three factors (see diagram below). To slow down or to stop corrosion, one of these factors must be eliminated. OH - OH - Oxygen Electrolyte (humidity) Fe ++ Corrosion e - Rust e - Carbonation Chlorides Steel depassivation Passivation layer Damp concrete acting as the electrolyte Steel reinforcement STEEL DEPASSIVATION Exposure of reinforced concrete to chloride ions is the primary cause of premature corrosion of steel reinforcement. The intrusion of chloride ions, present in de-icing salts and seawater, into reinforced concrete can cause steel corrosion if oxygen and moisture are also available to sustain the reaction. Chlorides dissolved in water can permeate through sound concrete or reach the steel through cracks. Chloride-containing admixtures can also cause corrosion. CHEMISTRY FOCUS Corrosion of steel rebar occurs when concrete ph falls below 9. Two specific phenomena are the cause of this ph reduction: Carbonation: The water reacts with the carbon dioxide (CO 2 ) to form carbonic acid lowering the ph H 2 O + CO 2 = H 2 CO 3 Then, the carbonic acid reacts with the lime: H 2 CO 3 + Ca(OH) 2 = CaCO 3 + 2H 2 O Once the carbonation reaches the reinforcement, the corrosion of the steel begins. Chlorides: Chlorides from de-icing salts, sea water, or chloride-based accelerators containing calcium chloride react with the iron: Fe Cl - + 2H 2 O = Fe(OH 2 ) + 2H + + 2Cl -- The reinforcement starts to corrode when the [Cl-]/[OH-] ratio is greater than 1. Once this ratio has been achieved, acids form, which then triggers the corrosion process. The OH- ions come primarily from the concrete. A [Cl-]/[OH-] ratio of 1 is equal to a chloride content of 0.4% in relation to cement content. chlorides etc), new anodic zones form in the immediate vicinity of the repaired areas, which have now become cathodic zones. In the medium-term, the consequence of this polarity change is an acceleration of corrosion in the areas adjacent to where the repairs were carried out. To prevent this problem, it is necessary to treat the entire structure. THE BATTERY EFFECT During repairs to a reinforced concrete structure showing the first signs of corrosion the delaminating concrete is removed from around the rebar (see French standard NF P95-101). The layer of rust covering the rebar is removed and then repairs are completed using a new mortar to re-create the profile. This naturally alkaline mortar restores the original level of protection to the rebar. Since the concrete adjacent to the repair zone remains contaminated by the corrosion agents (carbonates,

4 CORROSION TREATMENT TREATMENT OF CARBONATED CONCRETE: 761 LANKOSTEEL, AN IMPREGNATING CORROSION INHIBITOR Impregnating corrosion inhibitors can be classified into three groups: Group 1 Absorption inhibitors: the product adheres to the surface of steel and forms a protective layer that acts as a barrier against polluting agents. Group 2 Oxidizing inhibitors: the product protects steel by forming a compact layer of iron oxide. These products require oxygen in order to be effective and also must be precisely measured. Group 3 Non-oxidizing inhibitors: the product forms an electrochemical barrier on the surface of the rebar. 761 LANKOSTEEL! Rapid penetration into concrete! Solvent-free! No film formation! No alteration of concrete appearance! Compliant with principle 11, method 11.3 of standard EN ! Minimal 761 LANKOSTEEL concentration of 0.001% of concrete weight at level of rebar 760 LANKOPASSIV! Corrosion-resistant coating! Protection of concrete rebars! Single component! Can be covered after 2 hours! Compliant with EN label GALVANIC PROTECTION OF CHLORIDE-AFFECTED CONCRETE: GALVASHIELD SACRIFICIAL ANODES GALVASHIELD These anodes are composed of a sacrificial core of activated zinc in a specially-formulated cement mortar. This procedure requires no external electric power supply. Whether for cathodic prevention, corrosion control or cathodic protection, the GALVASHIELD range of products is designed to provide suitable solutions for all required levels of protection: GALVASHIELD XP, GALVASHIELD CC or GALVASHIELD DAS. Level of protection Description Current density GALVASHIELD Cathodic prevention Prevents new areas of corrosion occurring ma/m2 XP, XP2, XP4, XPT CC65, CC100, CC135 Corrosion control Significant reduction of active corrosion 1-7 ma/m2 XP2, XP4 CC65, CC100, CC135 Cathodic protection High level of protection Stops active corrosion 5-15 ma/m2 DAS

5 PROTECTING AND REPAIRING CONCRETE REPAIRS TO CONCRETE STRUCTURES AND BUILDINGS STRUCTURAL REPAIRS RAPID REPAIRS 731 LANKOREP STRUCTURE! Thickness: 5 to 70 mm per layer! Compliant with EN class R4 735 LANKOREP RAPIDE 770 LANKOREP FIN RAPIDE! Thickness: 5 to 70 mm per layer! Compliant with EN class R4! Thickness: 2 to 70 mm per layer! Compliant with EN class R3 735 LANKOREP RAPIDE! Thickness: 5 to 70 mm per layer! Compliant with EN class R4 770 LANKOREP FIN RAPIDE! Thickness: 2 to 70 mm per layer! Compliant with EN class R3 NON-STRUCTURAL REPAIRS 730 LANKOREP FIN! Thickness: 2 to 70 mm per layer! Compliant with EN class R2 HERITAGE REPAIRS 732 LANKOREP FAÇADE! Thickness: 1 to 40 mm per layer! Compliant with EN class R2 CASTABLE REPAIRS 777 LANKOIMPER SURFAÇAGE! Thickness: < 3 mm! Compliant with EN class R4! Surfacing/waterproofing/bonding 733 LANKOREP BLANC! Thickness: 2 to 50 mm per layer! Compliant with EN class R3! White 734 LANKOREP PATRIMOINE! Thickness: 3 to 50 mm per layer! Base = CL90 hydrated lime ANTI-ABRASION AND ANTI-CORROSION REPAIRS 720 LANKOREP EPOXY! Anti-abrasion and anti-corrosion mortar! Thickness: 2 to 50 mm! Solvent-free! Non-shrinking PROTECTION 780 LANKOREP FLUIDE! Thickness: 15 to 250 mm per layer! Compliant with EN class R3! Formwork removal may be achieved after 4 hours 745 LANKOCOTE CM 660! Compliant with standard EN (principles 1, 2, 5 and 8)! Replicates the colouring of concrete structures (choice of shades)! Easy application: by roller, brush or spraying machine

6 SEWAGE AND WATER NETWORKS REPAIRS TO VAULTS AND ARCHES IN SEWAGE AND WATER NETWORKS REPAIRS TO CHIMNEYS, VENTILATION SHAFTS IN SEWAGE AND WATER NETWORKS 736 LANKOCRETE RESEAUX Compliant with EN class R2 Can be pumped over large distances Application up to 80 mm Safety compliance certificate (CLP) granted by French health and safety committee CNR abrasion index (after 28 days): < BREPOXY Resistant to acids, dilute acids and dilute bases Water resistant Application to dry or slightly damp substrates REPAIRS TO APRONS AND ABUTMENTS IN SEWAGE AND WATER NETWORKS 738 LANKOCRETE ABRASION 739 LANKOCRETE SPECIAL High abrasion resistance Large thicknesses up to 80 mm Compliant with EN class R3 CNR abrasion index (after 28 days): < 1 High abrasion resistance Large thicknesses up to 80 mm Compliant with EN class R3 CNR abrasion index (after 28 days): < 1 INJECTION INJECTION GROUT 737 LANKOREP FISSURE Very fluid grout Very high mechanical strength

7 STRUCTURAL REINFORCEMENTS LANKOSTRUCTURE CARBOLAM LANKOSTRUCTURE CARBOLAM KEY CHARACTERISTICS A range of carbon fibre-infused strips for enhancing the bending strength of concrete beams and floors. These strips are bonded directly to the structure requiring reinforcement using epoxy adhesive 50 CARBOLAM COLLE. ADVANTAGES Structural reinforcement with no risk of overloading the structure nor of bulking that occurs when reinforcing with shotcrete. Shorter return to service lead times than with solutions involving encasing with concrete that is either spray projected or cast on site. Strips: LANKOSTRUCTURE CARBOLAM Tensile strength: > MPa Elasticity modulus in tension: > 160 GPa Elongation at failure: > 1.33% Infused strip widths: 50 mm (40 Carbolam 50), 80 mm (41 Carbolam 80), 100 mm (42 Carbolam 100), 120 mm (43 Carbolam 120) Available lengths: 25 metre, 50 metre and 100 metre Thickness: 1.2 mm ATEX CSTB No 1982 Adhesive: 50 CARBOLAM COLLE Advantages: vitreous transition temperature Tg (EN 12614): C (this allows a higher service temperature than most other commercially available systems) Packaging: 7.5kg and 2kg kits LANKOSTRUCTURE CARBOTEX LANKOSTRUCTURE CARBOTEX KEY CHARACTERISTICS Uni-directional carbon thread enriched fabric for enhanced bending strength and shearing force resistance of concrete beams, columns and concrete walls. Applied by bonding to the component requiring reinforcement using epoxy adhesive 51 CARBOTEX COLLE. This technique requires that the angles be canted or splayed. ADVANTAGES Moulds easily to the shape of the structure, even cylindrical forms and cuboidal sections. Unaffected by corrosion. Small, easy-totransport rolls. Fabric: LANKOSTRUCTURE CARBOTEX Tensile strength: > MPa Elasticity modulus in tension: > 221 GPa Unaffected by corrosion Widths available: 300 mm (30 Carbotex 300) and 580 mm (31 Carbotex 580), for a standard length of 50 metre ATEX CSTB No 1982 Adhesive: 51 CARBOTEX COLLE Initial mixture viscosity: MPa at 20 C and MPa at 30 C Tensile strength (EN ISO0527): 34 MPa Compressive strength (EN 12190): 60 MPa Bending strength (EN ): 49 MPa Elasticity modulus (EN 13412): MPa Bonding performance: > 3 N/mm² (on concrete) Packaging: 3.2kg kit Advantages: The thixotropic compound offers excellent fabric impregnation qualities, enables work to be carried out in ambient conditions up to 35 C and is suitable for both vertical and horizontal applications

8 PAREXLANKO ALSO PROVIDES ON-SITE TECHNICAL EXPERTISE AND SUPPORT For over 30 years, our regional network of specialized technicians has been providing the very best back-up service and technical advice to customers throughout France. Technical Info service Technical recommendations: Studying the specific technical characteristics of your worksites Drafting written recommendations & guidance Getting started: Our technicians will be delighted to come to your site and provide key advice on using our products Phone 0.15 per min + connection charge 0.15 per call + connection charge PARTNER FOR YOUR FINEST WORK Parexlanko is the trademark of ParexGroup S.A. ParexGroup S.A. Technical Mortars Department 19 Place de la Résistance CS Issy-les-Moulineaux cedex France - Tel. : +33 (0) parexlanko.com Acting for paper recycling with ParexGroup and Ecofolio Photo credit : Fotolia - ParexGroup / June 2016 / Design : blend.fr