DE3638646A1 - Process and products for refurbishing and finishing concrete - Google Patents

Abstract

The process for refurbishing old concrete and/or finishing new concrete is carried out by 1. Removing all loose and slack concrete parts, 2. Preliminary cleaning by sand blasting, 3. If necessary exposing the reinforcement in the region of carbonized and/or chloride-containing zones, 4. Application of a filler material in the region of the exposed reinforcement and/or depressions formed, 5. Application of a carbonization and/or chloride brake and, if appropriate, a protective coating, wherein 6. If appropriate, exposure of the reinforcement is omitted, 7. As the filler material, carbonization brake and/or chloride brake, a mortar or concrete is used which, in addition to the conventional aggregates of usual composition, contains: a) 300 to 600 and preferably 400 to 500 kg/m<3> of cement in the mortar or concrete, b) products forming fine air pores, c) additives which reduce the microporosity, and d) preferably no setting accelerators, and this mortar or concrete is applied by the dry or wet spraying process to the entire old or new concrete surface in a layer thickness from 4 to 60 and preferably 8 to 30 mm and, if desired, further smoothed.

Description

The present invention relates to methods and means for the rehabilitation of old concrete and / or after improvement of new concrete.

The renovation of old concrete is always necessary when the outer layers of the concrete scream through carbonation have lost their alkalinity and thereby are no longer able to get into it to protect embedded reinforcement against corrosion. Next There is a need to renovate old concrete if by penetration of chloride into the area of Reinforcement the corrosion of the reinforcement is triggered. Finally, renovation is necessary if the waiter surface of the concrete has become defective for other reasons is. The reworking of new concrete is always then necessary if the reinforcement cover is not sufficient is sufficiently thick and / or due to mixing errors or subsequent contamination of the concrete not the ge required strength.

Up to now, old concrete has been renovated by that first the loose and loose concrete parts are removed and was then pre-cleaned by sandblasting. Then the reinforcement in the area of carbonization or the penetration of chloride mechanically exposed. The exposed reinforcement as well as all other given if any depressions were created with a fill material grouted. After that, they mostly became thin Carbonization and / or chloride brake and given if necessary, a protective coating is applied. As a carboni Braking and / or chloride brakes were mostly art resins, for example based on epoxy, or cement art Tempered materials are used that are re-entering penetrate carbon dioxide and chloride at least have velvet.  

The main disadvantage of these materials was that rin that they usually do not have enough water vapor were permeable so that these layers were relative often from the concrete surface due to bubbles loosened and sooner or later cracked or peeled off. The same effect was often unintentionally caused by it aims that an insufficiently water vapor permeable protective coating was applied. Another after part of these layers of protection is that they re relatively unstable against strong light as well were the attack of chemicals.

As filling material in the area of the exposed reinforcement and / or resulting depressions were either kor anti-corrosion plastic compounds or common fu Use gene mortar based on cement and aggregates det, which is also a new passivation of the reinforcement caused.

These methods of rehabilitation of old concrete show a number of disadvantages: first of all it is very labor and costly after removing the loose and loose components and sandblasting to expose the reinforcement in the area of carbonized and / or zones containing chloride. It is still on agile, in the area of exposed reinforcement and the resulting fillings It has also been shown that at the borders areas between the old concrete and the new filler material relatively frequently pitting corrosion on the blast tion was observed. Finally, the application the carbonization and / or chloride brake and ge if necessary, one protective coat of paint, not just another Operations and material costs required, but a lot only the desired effect for a relatively short time shown.

The invention has therefore set itself the task as simple and inexpensive as possible, however also to develop a reliable method with which it is possible to renovate both old concrete as well to repair new concrete. This should be done if possible both labor and material costs be reduced and yet reliable and if possible long-term the desired effect can be guaranteed.

This task can be surprisingly simple and reliable be solved by a process for the rehabilitation of old concrete and / or repair of new concrete by

• 1. Remove all loose and loose concrete parts,
• 2. pre-cleaning by sandblasting,
• 3. If necessary, expose the reinforcement in the area carbonized and / or chloride-containing zones,
• 4. Apply a filler in the area of the free reinforcement and / or deepening gene,
• 5. Applying a carbonization and / or chloride brake and, if necessary, a protective coating,

characterized in that

• 6. Ver, if necessary, on the exposure of the reinforcement is canceled
• 7. a mortar or concrete is used as the filler, carbonization and / or chloride brake, which contains, apart from the usual additives, the usual composition:
  • a) 300 to 600, preferably 400 to 500 kg / cm ³ cement in mortar or concrete,
  • b) air-entraining agents,
  • (c) additives which reduce microporosity, and
  • d) preferably no setting accelerators;
• and this mortar or concrete in dry or wet spraying on the whole old or new Concrete surface in a layer thickness of 4 to 60, in front preferably applied 8 to 30 mm and desired if smoothing is carried out.

According to the new procedure, it is only necessary dig to perform steps 1 and 2, that is, to remove all loose and loose concrete parts and pre-cleaned by sandblasting. Exposing the Reinforcement in the area of carbonized and / or chloride containing zones can already be omitted, since after the new a mortar or concrete is applied, which due to its special composition in the Is able, also through the carbonized and / or chlo zones containing the reinforcement again Passivate corrosion. Of course it is possible, even in the inventive method Reinforcement in the area of carbonized and / or chloride exposed zones beforehand. However, it has shown that on this complex process step can be dispensed with.

The mortar or concrete used as a filler, carbonization and / or chloride brake is a relatively fat mortar or concrete, which has a considerable excess of free, water-soluble calcium hydroxide and therefore when applied to the old carbonized and / or chloride-containing concrete Layers repassivated and the passivation re-passivated. The relatively high content of Ze ment of 300 to 600, preferably 400 to 500 kg / cm ³ is on the other hand not yet so fat that it shrinks or cracks when setting.

Due to the content of fine air-entraining agents such as for example Vinsol resins, the shrinkage will continue pushed back and the elasticity of the tied Mortar or concrete increased. Ensure the fine air pores also afford that the set mortar or Concrete is frost resistant, which is very long ongoing renovation of the old concrete contributes. By the additives that reduce the microporosity, in particular special means that bind pozzolana will Penetration of carbon dioxide and chloride considerably brakes, so that also in this regard a long lasting effect is guaranteed. The invention Mixtures used for mortar and concrete are, however still permeable to water vapor, so it doesn't it can happen that the applied layer through Water vapor from inside the old or new concrete is lifted off like a bubble.

It has also been shown that the invention mixtures used for mortar and concrete preferably no setting accelerators should be added because this the stability, flexibility and microporosity of the set mortar or concrete sen. So far, setting accelerators are always ver has been applied when mortar or concrete in the dry and Wet spray processes should be applied. Because it according to the invention is entirely sufficient, the entire old or new concrete surface with a layer thickness of 4 to 60 mm, preferably cover 8 to 30 mm, can on the Ab binding accelerators are dispensed with. This relative thin layers adhere and bind even then free if no setting accelerator is added the.  

By applying the special mixtures for mortar tel or concrete in the dry or wet spray process the entire old or new concrete surface is possible Lich, in a single operation and with one material, the exposed reinforcement and / or to fill in any other wells that may have arisen and all carbonized and / or chloride-containing Renovate surface. So it doesn't come anymore to the dreaded pitting corrosion in the border area between old carbonized and / or chloride-containing Concrete and new filling material.

If desired, the freshly applied can of course Material to be smoothed. In principle, it is too possible to restore or improve the areas in To provide a protective coat in the usual way. However, care should also be taken that these protective coatings are at least permeable to water vapor are. It is thus according to the method according to the invention possible to renovate and / or repair concrete to be carried out in such a way that visually appealing surfaces Chen arise, which if desired also colored can be tet.

The costs of the method according to the invention are high Lich lower than with the previously known methods, because initially during the preparatory work on the exposure of the Reinforcement can be omitted. So it just becomes a Fraction of the renovation needs to be removed removed from concrete. The working steps of Aufbrin filling material in the area of the exposed Reinforcement and / or indentations as well as there after applying a carbonization and / or Chloride brakes are combined into one work paced with a relatively inexpensive material that can be easily processed.  

The material costs are also reduced by that gear with relatively small amounts of this material can be processed, as with layer thicknesses of 4 to 60, preferably 8 to 30 mm. Decide one there is the advantage of the method according to the invention but above all in that one carried out with it Restoration and / or rework for many years dig is.

Another advantage of the method according to the invention is that more common with the usual supplements Composition can be worked. It can therefore as a surcharge on the customary local materials can be used. It can in particular other quartz sands, but also limestone in the for mortar or concrete prescribed grain sizes and grain sizes distributions are used. By the rest of him Components of the mortar used in accordance with the invention or concrete you get an externally uniform, durable stable layer, which leads to a renewed Passivation of the reinforcement against corrosion contributes and renewed damage from carbonization and / or Chloride slowed down at least considerably.

They can be used as fine air pore forming agents for a long time proven Vinsol resins (approx. 85% resin acids and approx. 15% phenolic products, manufacturers for example Hercules) be used. In principle, others could and new air-pore-forming agents to be developed tel are used because of the Po formed Resistance to frost of the mortar or concrete guarantee.

As additives that reduce the microporosity come especially additives that are pozzolanic the.  

This includes in particular fly ash, microsilica (Si licafume), ground trass and hollow microspheres.

The subject of the present invention is not only that Process for the remediation and / or improvement of Be ton, but also the means to carry out this Procedure and the use of these agents for Sa old concrete and / or rework of new em concrete.

The invention is illustrated in the examples below explains:

example 1

Grained limestone of the following grain sizes was used:

0-0.3 mm 128.00 kg 0.3-0.6 mm 112.00 kg 0.6-1.0 mm 80.00 kg 1.0-1.5 mm 112.00 kg 1.5- 2.5 mm 144.00 kg 2.5-3.5 mm 224.00 kg limestone total 800.00 kg

It was mixed with:

Portland cement 35 F 189.00 kg microsilica (silica fume) 11.00 kg 200.00 kg

Methyl cellulose 0.19 kg Air entraining agent (Vinsol® resin) 0.28 kg Pump aid 904 (Sika) 2.00 kg

Dry mixture total 1002.47 kg

This mixture was mixed with approx. 76 l water / ton concrete Dry spray process processed and in thicknesses between 8 and 30 mm on a renovation and therefore pre-cleaned and sandblasted concrete applied, but without the reinforcement in the car parts that have been bonized and / or interspersed with chlorides was exposed. The material also holds and binds in the parts on which it is opened laterally or from below was injected. The follow-up examination of the renovated areas Chen for a long period of time showed that it was too a re-passivation of the reinforcement that Layers of frost resistance and a new one Penetration of carbon dioxide and / or chloride not solid was adjustable.

Example 2

Results similar to those in Example 1 were obtained with a mixture that instead of 2 kg of pumping aid 904 only 1.5 kg of pumping aid 904 and 1.0 kg of condenser for spraying clay based on melanin resin (manufacturer Süddeutsche Kalk nitrogen plants) contained.

Example 3

Results similar to those in Example 1 were obtained with a mixture containing 1.5 kg of pumping aid 904 and a retar which contained based on sodium phosphate (0.18 kg).

Claims (7)

1. Procedure for the rehabilitation of old concrete and / or after improvement of new concrete

• 1. Remove all loose and loose concrete parts,
• 2. pre-cleaning by sandblasting,
• 3. if necessary, exposing the reinforcement in the area of carbonized and / or chloride-containing zones,
• 4. Application of a filler material in the area of the exposed reinforcement and / or resulting depressions,
• 5. Applying a carbonization and / or chloride brake and, if necessary, a protective coating,

characterized in that

• 6. if necessary, the reinforcement is not exposed,
• 7. a mortar or concrete is used as the filler, carbonization and / or chloride brake, which contains, apart from the usual additives, the usual composition:
  • a) 300 to 600, preferably 400 to 500 kg / cm ³ cement in mortar or concrete,
  • b) fine air pore forming agents,
  • (c) additives which reduce microporosity, and
  • d) preferably a setting accelerator;
• and this mortar or concrete in the dry or wet spray process on the entire old or new concrete surface in a layer thickness of 4 to 60, preferably 8 to 30 mm before applied and if necessary smoothed.

2. The method according to claim 1, characterized in that Use Vinsol resins as a fine air pore-forming agent be det.   3. The method according to claims 1 or 2, characterized records that as an additive to reduce the micropo pozzolanic setting agents are used the. 4. Means for carrying out the method according to claims 1 to 3, consisting of a dry premix ent except usual supplements usual composition

• a) 300 to 600, preferably 400 to 500 kg / cm ^{3 of} cement in mortar or concrete,
• b) air-entraining agents,
• (c) additives which reduce microporosity, and
• d) preferably no setting accelerators.

5. Use of dry or wet spray on portable dry premixes consisting of usual supplements of usual composition and

• a) 300 to 600, preferably 400 to 500 kg / cm ^{3 of} cement in mortar or concrete,
• b) air-entraining agents,
• (c) additives which reduce microporosity, and
• d) preferably no setting accelerators,

for the renovation of old concrete and / or reworking of new concrete.