DE102017120798A1 - Mortar and concrete based on one-component geopolymers for sewer construction and sewer rehabilitation - Google Patents

Abstract

A mortar or concrete based on one-component geopolymers for sewer construction and sewage sewer rehabilitation is proposed, the mortar and concrete comprising a geopolymer of a silica and a sodium aluminate and an additive comprising CaO.

Description

The invention is in the field of construction and the building materials industry, and relates in particular Kanalinstandsetzer / -sanierer, z. B. in the sewage sector, and manufacturers of mortar and concrete.

Concrete components or masonry components (in particular pipes, inlets, mating or joint pieces, shafts, collectors) in wastewater treatment plants are exposed to extreme chemical stresses, in particular due to biogenic sulfuric acid corrosion or other acid attacks (eg organic acids). Therefore, the repair products such as mortar and concrete for these components must have a very high resistance to biogenic sulfuric acid corrosion, so as not to prematurely require a renewed repair. The mineral mortars or concretes previously used for this purpose meet this requirement only conditionally, are very expensive or subject to problems in the application. For example, the use of powdered waterglass as an activator involves considerable practical problems.

Against this background, a repair mortar and / or a repair concrete according to claim 1 is proposed. Under mortar and concrete, building materials are understood to differ essentially only by the maximum size of the aggregate grain (aggregate) used in each case. The limit is generally 4 mm, depending on the standard or literature. If the grain size is below this limit, it is called mortar; if it is above it is called concrete. Furthermore, mortar and concrete here, as customary and depending on the context, both a dry mortar or a dry concrete and the hardened mortar or concrete understood.

Other embodiments, modifications and improvements will become apparent from the following description and the appended claims.

According to one embodiment, a mineral acid-resistant mortar or concrete for the construction and renovation of wastewater, z. B. for sewer pipes, proposed. A dry mortar or concrete underlying the mortar or concrete contains a starting geopolymer mixture comprising a silica, a sodium aluminate and an additive, the additive containing CaO. Under a geopolymer here is an aluminosilicate with network structure, which has arisen by the alkaline activation of solid silicate starting materials via solution and precipitation processes understood. Examples of geopolymers are metakaolin activated with sodium silicate solutions (water glass) and fly ash or fly ash blastfurnace-sand mixtures activated with sodium silicate solutions or sodium hydroxide solutions.

The proposed repair mortar and the proposed repair concrete after setting on the high acid resistance of geopolymer mortars or so-called silicate mortars, but it can be mixed with water and made to harden, so be prepared without using a highly alkaline activator. This represents a significant advantage over other (activator solution based) systems in processing.

According to another embodiment, the additive of the proposed mortar or of the proposed concrete is selected from: a ground blastfurnace slag, a coal fly ash with at least 6% CaO, a lignite fly ash and a cement.

The named additives provide soluble CaO. The advantage of adding soluble CaO to the reaction system is the faster solidification and faster hardening as opposed to the lack of soluble CaO addition.

According to another embodiment, the additive comprises a ground blastfurnace slag. The proportion of ground blastfurnace slag to the binder of the mortar or concrete is between 2.5 to 50% by mass, in particular between 2.5 and 30% by mass, for example between 5 and 25% by mass.

Advantageously, such water-mixed dry mortar or dry concrete has improved rheological properties over a mortar or concrete based on a geopolymer containing only silica and sodium aluminate.

According to a further embodiment, the granulated blast furnace slag used in the mortar or concrete has a d (90) value of ≦ 0.08 mm, in particular of ≦ 0.07 mm, preferably of ≦ 0.063 mm.

The advantage of these particle sizes is that the granulated blastfurning material dissolves sufficiently quickly to cause solidification and hardening of the mortar or concrete within 24 hours.

According to a further embodiment, the additive of the proposed mortar or concrete is selected from: a Portland cement, a cement from Portland clinker, a cement which may be either pure or blended, the additive for blending either a latent hydraulic material, a pozzolan or even a Mixture of latent hydraulic material and pozzolans may be.

The advantage of these cements is that they dissolve sufficiently quickly to cause solidification and hardening of the mortar or concrete within 24 hours. The resulting materials correspond to those in DIN EN 197-1 mentioned.

According to a further embodiment, the silica comprises a microsilica, a siliceous residue from the chemical industry or a biogenic ash, in particular rice husk ash.

In this context, microsilica is understood to mean the same as silica fume. Advantages of a microsilica are a high specific surface area of at least 5 m ² / g, a high reactivity due to the amorphous structure and a high SiO ₂ content of at least 80 mass%.

According to a further embodiment, the content of CaO, based on the total solids mass of the binder of the mortar or concrete, is between 1 mass% and 20 mass%, in particular between 1 mass% and 12 mass%, for example between 2 mass -% and 10% by mass.

Advantages of such levels of CaO are faster solidification and hardening than without CaO addition (as described above), while at the same time the major reaction product remains a geopolymer. From about 20% by mass of CaO, a transition from geopolymer to calcium silicate hydrate (C-S-H) takes place as the main reaction product. C-S-H is the bonding phase that results from the hydration of conventional concrete and is undesirable for the applications described herein.

According to a further embodiment, a CaO content is based on a mass of a binder, comprising the geopolymer and the additive between 1 to 20% by mass, preferably between 5 to 17% by mass, in particular 10 ± 2% by mass.

Advantageously, such a content leads to faster solidification and hardening, compared with the behavior without CaO addition. At the same time, the CaO content is not so high as to quantify the acid resistance of the mortar or concrete (quantified eg by residual compressive strength after storage for seventy days in sulfuric acid at pH = 1) below the required limit of (eg 75%) above storage) lowers.

• - 6 bis 18 Masse-% Microsilica, insbesondere 10 bis 15 Masse-% Microsilica und/oder eines anderen kieselsäurereichen Reststoffs;
• - 2,5 bis 7,5 Masse-% Natriumaluminat, insbesondere 3-8 % Masse-% Natriumaluminat;
• - 2,5 bis 7,5 Masse-% Hüttensandmehl, insbesondere 3-7 Masse-% Hüttensandmehl;
• - 50 bis 75 Masse-%, insbesondere 55 -75 Masse-% Quarzsand mit Korngrößen unterhalb von 2 mm, wobei der resultierende Mörtel, also die Trockenmischung, mit 7-14 Masse-% Wasser, bezogen auf die Masse der Gesamtmenge verarbeitet wird.

According to further embodiments, the mortar proposed above comprises:

• - 6 to 18% by mass of microsilica, in particular 10 to 15% by mass of microsilica and / or another siliceous residue;
• 2.5 to 7.5% by weight of sodium aluminate, in particular 3-8% by weight of sodium aluminate;
• - 2.5 to 7.5% by mass of blastfurnace slag flour, in particular 3-7% by weight of blastfurnace slag flour;
• - 50 to 75% by mass, in particular 55-75% by mass of quartz sand with particle sizes of less than 2 mm, the resulting mortar, ie the dry mixture, being processed with 7-14% by mass of water, based on the mass of the total amount.

For example, the proposed mortar comprises: 6-18% by mass of microsilica and / or a siliceous residue; 2.5-7.5% mass% sodium aluminate; 2.5-7.5% by mass of blastfurnace slag flour; 55-75% by mass of quartz sand with grain sizes below 2 mm (for mortar), the mortar being used with 5-18% by mass of water, based on the total amount.

• - 6 bis 18 Masse-% Microsilica, insbesondere 10 bis 15 Masse-% Microsilica und/oder eines anderen kieselsäurereichen Reststoffs;
• - 2,5 bis 7,5 Masse-% Natriumaluminat, insbesondere 3-8 % Masse-% Natriumaluminat;
• - 2,5 bis 7,5 Masse-% Hüttensandmehl, insbesondere 3-7 Masse-% Hüttensandmehl;
• - 50 bis 75 Masse-%, insbesondere 65 -75 Masse-% Gesteinskörnung mit Korngrößen bis 16 oder 32 mm, wobei der resultierende Beton mit 7-14 Masse-% Wasser, bezogen auf die Gesamtmenge verarbeitet wird.

According to further embodiments, the proposed concrete comprises:

• - 6 to 18% by mass of microsilica, in particular 10 to 15% by mass of microsilica and / or another siliceous residue;
• 2.5 to 7.5% by weight of sodium aluminate, in particular 3-8% by weight of sodium aluminate;
• - 2.5 to 7.5% by mass of blastfurnace slag flour, in particular 3-7% by weight of blastfurnace slag flour;
• - 50 to 75 mass%, in particular 65-75 mass% aggregate with particle sizes up to 16 or 32 mm, the resulting concrete with 7-14% by mass of water, based on the total amount is processed.

Advantages of the composition described are, as described above, the possibilities of rendering the mortar or the concrete watery, of ensuring a high acid resistance and of setting and hardening of the mortar or of the concrete, preferably within 24 hours.

According to a further embodiment, a method is proposed for the rehabilitation of a sewer, in particular for the rehabilitation of a concrete component in the sewer area, comprising the following steps: providing a mortar or concrete according to one of the previously described embodiments; Apply the mixed mortar and / or concrete to a wall of the sewer to be renovated and harden the applied mortar or concrete.

According to another embodiment, hardening of the water-applied mortar or concrete within 24 hours by introducing a heated and optionally humidified air into the sewer, wherein the heated and optionally humidified air has a temperature of 50-90 ° C and the introduction via a period of at least 6 hours.

The short setting time offers particular advantages for the sewer rehabilitation, as this can minimize the costs of introducing heated and optionally humidified air and the further steps can be started earlier. In the renovation of large walk-in channels, the drainage and drainage is an economically significant factor. There are regularly high pumping costs. The projects are at high risk due to unforeseeable rain events. An early water exposure time of a coating mortar or concrete thus leads to a cost savings. The repair mortar or concrete proposed here advantageously has an early water load time.

According to another embodiment, the hardening of the water-applied mortar or concrete takes place at room temperature.

Advantageously, under certain circumstances, a relatively long hardening time can be tolerated, so that one would do without the introduction of hot air in these cases. Also, under favorable conditions, for example, a surface / volume ratio of at least 13 dm ² / dm ³ , a hardening within 24 h takes place without additional heat.

According to a further embodiment, the use of a mortar and / or concrete according to the above embodiments for the rehabilitation of a concrete component in the sewage area is proposed.

This is where the pronounced network structure of the silicates of the geopolymer formed during solidification causes a high acid resistance of the rehabilitated concrete components.

According to a further embodiment, the renovation comprises a spray application of the mortar or concrete.

The advantages of the spray application are obvious and are reflected in shorter construction and refurbishment times, reduced costs and improved material properties.

The above-described embodiments may be arbitrarily combined with each other.

Normally, mortar or concrete systems based on Portland cement are used for sewer rehabilitation. These contain Portland cement as a binder, aggregate (generally with largest grain 1-8 mm), optionally additives (inert, pozzolanic and / or latent hydraulic), fibers and organic additives (eg., To improve the processability of the adhesive bond or the shrinkage behavior). The hardened binder - the cement paste - is, however, due to the system (Kapilllarporöses system of acid-resistant phase components, eg Portlandit) inconsistent to the attack of acids. The result of this is that sufficient resistance and an acceptable service life of the mortar and concrete systems in case of acid attack can only be achieved by the densest possible structure. Dense structures, on the other hand, require low water / cement values and often also the addition of pozzolans in the form of fine powders. Both significantly deteriorate the workability of the mortar or concrete. In order to improve the processability, additives, in particular for improving the rheological properties, are used. The commercially available mortars and concretes therefore generally consist of a large number of interacting components. They are thus much more complex and also more expensive than conventional, eg. B. in building construction, mineral mortar systems or concretes.

In addition to the Portland cement-based systems, mortar systems based on alumina cement, EPC systems (epoxy resin-modified cement mortar), PCC systems (plastic-modified cement mortar), PC mortar (reaction resin mortar) and linings made of various materials (eg PVC , PE or glass) are used. The latter naturally require a much higher workload than mortar systems for the application; they are beyond i. A. also significantly more expensive than conventional mortar. The polymer-bound systems stand in the way of difficulties of the substrate requirements in the application. These systems require an underground moisture content of less than 5%, which can hardly be guaranteed in the sewer. Furthermore, the problem of vapor diffusion and osmosis is not solved.

More recently, so-called silicate or geopolymer mortars have also been used for sewer rehabilitation. These, like the conventional mortar systems, essentially contain aggregate and a binder. However, the binder system differs chemically fundamentally from Portland and alumina cement based binders. Because of the different kind The hardened binder matrix - the geopolymer - has a much higher resistance to acids in terms of composition and structure. Silicates of the geopolymer, unlike phyllosilicates and chain silicates, have a pronounced network structure. The disadvantage, however, is that the geopolymers must be activated to harden with a highly alkaline solution (ia sodium hydroxide solution or sodium silicate solution). The handling of these highly alkaline solutions at the site, however, is associated with significant problems in terms of environmental protection, aging and safety.

An alternative approach is the so-called one-component geopolymers. In these, the activator is in solid form in the binder, so that only water must be added to initiate the hardening reactions. When using powdered waterglass or sodium hydroxide as a solid activator, variations in dissolution rate may occur and the materials are highly hygroscopic, which limits the shelf life of the dry binders or dry mortars. The use of sodium aluminate as an activator for geopolymers is i. A. excluded, since for the desired properties of the hardened binder SiO ₂ / Al ₂ O ₃ ratios are necessary (i.A. SiO ₂ / Al ₂ O ₃ ≥ 3 mol / mol), the above the SiO ₂ / Al ₂ O ₃ ratio of customary solid starting materials (fly ash, granulated blastfurnace slag). Therefore, a use of sodium aluminate only makes sense if as a (further) solid starting material, a SiO ₂ -rich material is used. However, such one-component geopolymers with sodium aluminate as a solid activator have i. A. numerous technical shortcomings such. As the need for high hardening temperatures and a high sensitivity to variations in the setting temperature, low strength, high liquid content and thus high porosity, which previously excludes the use of these binders in the field of sewer rehabilitation.

The highly acid-resistant silicate mortars are sensitive to early water stress with increasing acid resistance. This leads to damage in practice shortly after the application. Another phenomenon that can be observed is the replacement of silicate mortars after several years. Which processes are responsible for this is not clear.

It is therefore an object of the present invention to accelerate the hardening at moderate temperatures, to reduce the liquid content and thus the porosity and increase the acid resistance and strength while ensuring the suitability for spray application of repair systems based on one-component geopolymers of silica and sodium aluminate provide.

Inventive solution

It was found that when adding CaO carriers, preferably from granulated blastfurnace slag, to systems made from silica and sodium aluminate, the above-described disadvantages of previous one-component geopolymers can be overcome. Here are referred to as slag granules materials that are produced by granulation and subsequent grinding of blast furnace slag. Slag granules generally contain between 30% and 50% CaO; typically the value is about 40%. The amount of the granulated blastfurnaceous meal added to the mortar or the concrete depends on the content of the granulated blastfurnaceous meal in CaO and is adjusted accordingly at CaO contents deviating from 40%, for example by B. at higher CaO levels, a smaller amount of blastfurnace sludge is added.

According to the invention, a particle size d (90) ≦ 0.063 mm is desired for the granulated blastfurnace. In this case, d (90) denotes a mean grain diameter at a sieve passage of 90%.

Due to the particle size distribution of the granulated blastfurnace, the i. A. is less fine than the particle size distribution of microsilica and other SiO ₂ -rich starting materials, and by providing slightly soluble CaO improve the rheological properties of the mortar or concrete and the technical properties of the hardened binder and based thereon mortar or concrete systems accordingly the above tasks.

Essential to the invention is the targeted use of CaO carriers, in particular granulated blastfurnace, for improving the properties of systems based on one-component geopolymers of silica and sodium aluminate.

The materials referred to here as Microsilica come for example from the Ferrosiliciumherstellung or the like. Likewise, siliceous residues from the chemical industry, eg. B. from chlorosilane production, as well as biogenic ashes, especially rice husk ash be used as microsilica. In principle, all SiO ₂ -rich substances with an SiO ₂ content> 80%, a specific surface area of at least 5 m ² / g and a predominantly amorphous or semicrystalline structure are used for the described use in a dry mix for the channel repair (mortar or concrete) or a corresponding reactivity as microsilica in question.

Sodium aluminate (NaAlO ₂ ) is on the one hand commercially available (eg for drinking water treatment); but also from waste streams, eg. As in the aluminum anodization can be obtained. The sodium aluminate used does not have to have the exact "stoichiometric" composition of NaAlO ₂ ; Deviations of the Na / Al value of 1 are possible. The use of sodium aluminate as an activator for geopolymers is i. A. excluded, since for the desired properties of the hardened binder SiO ₂ / Al ₂ O ₃ ratios are necessary, which are above the SiO ₂ / Al ₂ O ₃ ratio of conventional solid starting materials (fly ash, granulated blastfurnace). Therefore, a use of sodium aluminate only makes sense if as a (further) solid starting material a very SiO ₂ -rich material - such. B. Microsilica - is used. Typical ranges for the SiO ₂ / Al ₂ O ₃ ratio (molar) are 1.9-5.8 for hard coal fly ash, 3.4-6.2 for granulated blastfurnace flour and 35-1000 for microsilica; the typically desired range for geopolymers (solid starting material and activator together) is about 3-6.

• - hoher Säurewiderstand, dadurch erhöhte Marktchancen und Anwendungsbereiche;
• - keine Lagerhaltung und keine Verwendung hochalkalischer Lösungen notwendig, dadurch Kostenersparnis und höhere Marktakzeptanz;
• - Einsatz verschiedener kieselsäurereicher Reststoffe möglich, dadurch Kostenersparnis.

Economic advantages of the described embodiments are:

• - high acid resistance, thus increased market opportunities and applications;
• - no storage and no use of highly alkaline solutions necessary, thereby cost savings and greater market acceptance;
• - Use of various siliceous residues possible, thereby cost savings.

embodiment

• 12 Masse-% Microsilica (oder ein ähnliches SiO₂-reiches Material (vgl. Folgeabsatz);
• 5 Masse-% Natriumaluminat;
• 5 Masse-% Hüttensandmehl; bezogen auf die Trockenmasse des Mörtels sind dies 5,5 %.
• 69 Masse-% Quarzsand mit Korngrößen 0 bis 2 mm;
• 9 Masse-% Wasser.

Erfindungsgemäß werden typischerweise Microsilica, Natriumaluminat und Hüttensandmehl zusammen als Bindemittel eingesetzt, sodass ein Wasser/Bindemittel-Wert von 0,38 angestrebt ist.According to a practical embodiment, a recipe which can be used according to the invention for a repair mortar described here is as follows (details based on the total mass including water):

• 12% by mass of microsilica (or a similar SiO ₂ -rich material (see following paragraph);
• 5% by mass of sodium aluminate;
• 5% by mass of blastfurnace slag flour; this is 5.5% based on the dry mass of the mortar.
• 69% by mass of quartz sand with grain sizes 0 to 2 mm;
• 9% by mass of water.

According to the invention, microsilica, sodium aluminate and blast furnace slag are typically used together as binders, so that a water / binder value of 0.38 is desired.

The composition given refers to a formulation with quartz sand with a standard sieving line (passage at 2 mm: 100-98%, at 1.60 mm: 93 ± 5%, at 1.00 mm: 67 ± 7%, at 0, 50 mm: 33 ± 7%, at 0.16 mm: 13 ± 5%, at 0.08 mm: 0-3%) and microsilica as SiO ₂ -rich material. For finer sands and / or finer SiO ₂ -rich materials higher water contents of up to 18% are possible, for coarser sands and / or coarser SiO ₂ -rich materials lower water contents of not less than 6% are possible.

Hardening takes place at temperatures of 50 ° C to 90 ° C within a maximum of 24 h. In the rehabilitation of sewage collectors u. Ä., These temperatures can be achieved by introducing hot (possibly humidified) air. In principle, however, a hardening at room temperature is possible; Here are but, depending on layer thickness, boundary conditions, etc., z. T. significantly longer hardening times of up to several days required. For example, the mortars with binder contents hold between 20% by mass and 50% by mass at water contents of up to 19% by mass and surface / volume ratios of approximately 2.5 dm ² / dm ³ at a temperature of 23 ° C and one relative humidity of 50% within about 2.5 days. At surface / volume ratios of at least 13 dm ² / dm ³ , the hardening of the same mortar takes place under the same climatic conditions within 24 hours.

• 6-18 % Microsilica;
• 2,5-7,5 % Natriumaluminat;
• 2,5-7,5 % Hüttensandmehl; bezogen auf den Mörtel sind dies im Mittel 5,5 %.
• 55-75 % Quarzsand mit Korngrößen 0-2 mm oder 0-1 mm oder 0-0,5 mm;
• 5-18 % Wasser.

Preferred ranges for a mortar formulation are in% by mass (data based on the total mass incl. Water):

• 6-18% microsilica;
• 2.5-7.5% sodium aluminate;
• 2.5-7.5% granulated blastfurnace flour; based on the mortar, this is on average 5.5%.
• 55-75% quartz sand with grain sizes 0-2 mm or 0-1 mm or 0-0.5 mm;
• 5-18% water.

• 6-18 % Microsilica;
• 2,5-7,5 % Natriumaluminat;
• 2,5-7,5 % Hüttensandmehl; bezogen auf den Beton sind dies im Mittel 5,5 %.
• 55-75 % Gesteinskörnung mit Korngrößen 0-8 mm oder 0-16 mm oder 0-32 mm;
• 5-18 % Wasser.

An inventive recipe for a repair concrete is as follows (information based on the total mass including water):

• 6-18% microsilica;
• 2.5-7.5% sodium aluminate;
• 2.5-7.5% granulated blastfurnace flour; in terms of concrete, this is on average 5.5%.
• 55-75% aggregate with grain sizes 0-8 mm or 0-16 mm or 0-32 mm;
• 5-18% water.

While specific embodiments have been illustrated and described herein, it is within the scope of the present invention to properly modify the illustrated embodiments without departing from the scope of the present invention. The following claims are a first, non-binding attempt to broadly define the invention.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• DIN EN 197-1 [0014]

Claims (15)

Mortar or concrete for new construction and renovation in the wastewater sector, comprising: a geopolymer comprising a silica and a sodium aluminate and an additive comprising CaO. Mortar or concrete after Claim 1 wherein the additive is selected from: a ground blastfurnace slag, a coal fly ash, a lignite fly ash and a cement, the coal fly ash comprising at least 6% CaO. Mortar or concrete after Claim 2 wherein the additive comprises a ground blastfurnace slag and a proportion of the ground blastfurnace slag to the binder of the mortar or the concrete is between 2.5 to 50 mass%. Mortar or concrete after Claim 2 or 3 wherein the blastfurnace sludge has a d (90) value of ≤ 0.08 mm, in particular of ≤ 0.07 mm, preferably of ≤ 0.063 mm. Mortar or concrete after Claim 2 to 4 wherein the additive is selected from: a Portland cement, a cement from Portland clinker and a proportion of at least one latent hydraulic binder and / or a pozzolan. Mortar or concrete after Claim 1 to 5 wherein the silica comprises a microsilica, a siliceous residue from the chemical industry or a biogenic ash, in particular rice husk ash. Mortar or concrete according to one of the preceding claims, wherein a content of CaO based on a total solids mass of the binder of the mortar is between 1 mass% and 20 mass%. Mortar or concrete after one of the Claims 1 to 7 in which a CaO content based on a mass of a binder comprising the geopolymer and the additive is between 1 and 20% by mass, preferably between 5 and 17% by mass, in particular 10 ± 2% by mass. Mortar after Claim 1 comprising: 6-18% by mass of microsilica and / or a siliceous residue; 2.5-7.5 mass% sodium aluminate; 2.5-7.5% by mass of blastfurnace slag flour; 55-75 mass% quartz sand with grain sizes below 2 mm, the mortar with 5-18 mass% of water, in particular 7-14% by mass of water, based on the total amount, is set. Concrete after Claim 1 comprising 6-18% by mass of microsilica and / or a siliceous residue; 2.5-7.5 mass% sodium aluminate; 2.5-7.5% by mass of blastfurnace slag flour; 65-75% by mass of aggregate below 32 mm, the concrete being treated with 7-14% by mass of water, based on the total amount. A method of renovating a sewer, comprising - providing a mortar according to any one of Claims 1 to 9 or a concrete after one of the Claims 1 to 8th or 10 ; - applying the mixed mortar or concrete to a wall of the sewer to be rehabilitated; - hardening of the applied mortar or concrete. Method according to Claim 11 wherein hardening of the water-applied mortar or concrete takes place within 24 hours by introducing a heated and optionally humidified air into the sewer, the heated and optionally humidified air having a temperature of 50-90 ° C and the introduction over a period of time of at least 6 hours. Method according to Claim 11 wherein the hardening of the water-applied mortar or concrete takes place at room temperature. Use of a mortar or concrete in accordance with Claims 1 to 10 for the rehabilitation of a concrete component in the wastewater sector. Use after Claim 14 wherein the remediation comprises a spray application of the mortar or the concrete.