JP2002249367A - Calcium aluminate mortar used in spraying concrete wet process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mortar composition containing a binder and aggregate based on calcium aluminate, a concrete composition prepared from the mortar composition and a method for using the mortar composition. SOLUTION: This mortar contains a mixture comprising a calcium aluminate binder having around 40 wt.% or more alumina and aggregate of appropriate particle size, where the aggregate is calcium aluminate aggregate of 1.4 mm or smaller grain size, and at least around 35 wt.% of the mixture has around 100 μm or smaller grain size. The concrete composition prepared using the mortar, and the use in a spray concrete wet process for restoration by lining/ relining of sewage, draining system, pipe, manhole and related structure are also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mortar composition comprising a binder based on calcium aluminate and an aggregate, a concrete composition prepared therefrom, and
For example, its use in lining / relining of sewer and drainage systems, pipes, manholes and related structures, especially in sprayed concrete wet methods, in particular.

[0002]

2. Description of the Prior Art Pipes, manholes and related structures in sewer and drainage systems require regular rehabilitation. Water containing organic matter circulating in these pipes produces highly erodible acids by biological action. Generally, facilities such as pipes are made of cast or concrete, and are accompanied by PVC (polyvinyl chloride), HDPE
(High-density polyethylene), it may be covered with a protective material such as epoxy resin, but such pipe equipment is sometimes made of polyvinyl chloride, so there is a problem with their replacement. As it remains unresolved. Generally, these pipes are small in diameter, in contrast to sewer systems, which are made of cast or concrete and have a large diameter of 500 mm or more. Most reservoirs, reservoirs and manholes are made of concrete and need to be rehabilitated frequently due to corrosion from urban and industrial wastewater.

[0003] The use of mortars allows for a successful repair of the sewer system and has a number of known advantages. It is generally inexpensive, easy to handle and recoverable to the initial geometry of the pipe, further improving the durability of the structure. In addition, if necessary, a new restoration can be made with a new mortar upon resumption several years later. Mortars which allow rapid resumption, such as Portland cement or especially calcium aluminate cement mortar, are clearly preferred.

[0004] A so-called shotcrete method is generally selected as a main method for repairing, for example, when the frame condition is difficult due to the geometrical shape of the structure, which is more suitable than casting. However, there remains a problem to be solved when handling hardened mortar preparations.

[0005] The shotcrete method of construction involves the need to avoid dusting in enclosed environments, whether wet or dry, long transport times related to transport distance, types of work tools available on site, and emissions. The selection must take into account various factors such as the mechanical performance of the material to be used, productivity related to economic reasons, and the like. The type of construction method is ultimately determined by general work site constraints.

[0006] Another important problem encountered in preparing mortar for shotcrete applications is the lack of sufficient cohesion of the released mortar. Good binder / aggregate bond strength is also one of the requirements for good resistance to corrosion.

[0007] In the spray concrete wet method, generally, a mixture firstly comprises a binder (cement), an aggregate (fine, generally crystalline silica (siliceous) sand), a kneaded water mixture and additives. Made by mixing. This mixture is then generally pumped through the pipe through a pipe to a spray nozzle, where additives such as a coagulant are generally added. The mixture thus obtained is sprayed from the nozzle onto the concrete application surface by compressed air.

[0008]

The following are some of the known problems encountered with such shotcrete wet construction methods.・ The mortar mixture can be pumped (flowable) and can be sprayed. However, it is necessary to ensure effective adhesion to the concrete application surface, and the mixture is transferred to the spray nozzle by early curing. The mortar may block the pipe. The excess water present in the initial mortar mixture, which separates the mortar mixture, does not provide a sufficient compactness of the mixture, and is a single operation with water not consumed during hydration The thickness of the layer that can be sprayed by the amount is reduced.

[0009] The bonded aggregate composition used in the shotcrete wet process generally comprises a suitable, generally calcium silicate based aggregate, bonded by a binder (cement). Conventional rapid hardening cements that bind aggregate include alumina binders that generally contain at least 30% to 35% alumina, or Portland cements that typically contain less than 5% alumina.

In the present invention, it has been found that none of the mortars obtained by mixing conventional binders and aggregates is sufficient to prepare the concrete composition used in the shotcrete wet method. Accordingly, the Applicant has found a need for an improved mortar over conventional mortars, a new concrete composition prepared therefrom, and a shotcrete wet process using the same.

Accordingly, it is a primary object of the present invention to provide an improved mortar over conventional mortars, a composition of concrete prepared therefrom, and its use, especially in shotcreted wet processes.

[0012]

The first aspect of the present invention relates to a mortar containing a mixture of a calcium aluminate binder containing at least 40% by weight of alumina and an aggregate having an appropriate grain size. , Aggregate is 1.4mm
A calcium aluminate aggregate having the following grain size, wherein at least about 35% by weight of the mixture comprises about 100%
The grain size is smaller than μm.

[0013] European Patent No. 0,690,25
No. 8 discloses a mortar based on calcium aluminate. This mortar is applied to the inside of the pipe,
The pipe is then spun at 400 to 700 rpm for about 8 to 40 seconds. After the application of centrifugal force, the mortar is dried at about 60 ° C. Centrifugal force, coupled with drying, results in mortar cast or adhesion to the iron pipe.

[0014] However, this mortar is not at all suitable as a mixture of concrete compositions used in the shotcrete wet method, and is not suitable for use in sewage systems or the repair of related structures already installed on site. Is clearly inappropriate.

The mortar taught in EP 0,690,258, contrary to the mortar of the present invention,
Regardless of the wet method or the dry method, it cannot be used for a concrete composition that is actually used in a shotcrete method. The reason is simple: in the latter case, the mortar mixture is in a sufficiently pumpable (flowable) state and can be rapidly hardened so that it can be sprayed more easily, while effective for concrete application surfaces This is because it is necessary to adhere to the surface.

For example, the advantages of the formulation of the present invention when used in the spray concrete wet method are particularly as follows. A point that adheres to all smooth support surfaces.・ Thickness can be obtained by two or three operations. -The point where the denseness of the finishing layer and the tackiness for optimizing the density can be obtained.

The chemically identical nature of the mortar binder and the aggregate according to the invention improves the aggregate-binder bond and therefore the overall corrosion resistance of the material. Further, the calcium aluminate binding material of the present invention,
It contains a _C 12 _{A 7} small amounts. The amount is 0.6
%, Which prevents mortar from hardening and keeps the mortar pumpable, but is sufficient to hold the mortar in place and to trowel in place where necessary to allow for surface finish.

Further or alternative preferred features of the mortar according to the invention are as follows. The mortar binder is from about 2950 cm ² / g to about 46
It has a Blaine value (specific surface area) of 00 cm ² / g, preferably about 4500 cm ² / g. The mortar binder has about 53% alumina by weight; -The mortar binder is a so-called FOND known in the art.
It can be obtained by melting in a reverberatory furnace such as U (registered trademark). The mortar aggregate passes through a sieve of about 1.4 mm; The mortar contains about 97.7% calcium aluminate; The mortar further comprises one or more additives selected from the group consisting of leak resistance promoters, shrinkage inhibitors, internal strength promoters / separation inhibitors, and flow promoters.

In another embodiment, the invention is directed to a concrete
For the composition, the binder and aggregate as defined above are:
The binder: aggregate ratio is about 1: 1.9, the water: binder ratio is about
Present at 0.37. In yet another aspect, the present invention
Consists of mixing the mortar defined above with water.
The concrete composition obtained by the
About 14% water by weight of the dry ingredients of the cleat composition
And thereby a sufficiently low C₁₂A ₇Obtain phase components
be able to. (In formal notation in high aluminum cement technology
Is C = CaO, A = Al₂O₃)

In yet another aspect, the present invention is directed to a wet shotcrete using a concrete composition as defined above, suitable for lining / relining repair of sewer and drainage systems, pipes, manholes and related structures. Concerning the construction method. Other features and complementary advantages of the present invention are explained in further detail by the following illustrative but non-limiting examples.

[0021]

EXAMPLES Example 1: Preparation of a mortar according to the invention Secar 51 containing about 53% by weight of alumina, that is to say sold by the company Laphage Aluminate.
A calcium aluminate binder, which is a registered trademark, is mixed with a powder based on the calcium aluminate clinker manufactured by Laphage Aluminate, a so-called Alag®, an aggregate of the same mineral.

As a binder contained in the mortar according to the invention, it is possible to replace Secar51® with Calcoat®, the latter being Lapphage®.
Another type of calcium aluminate marketed by Aluminate, whose composition is also similar to Secar5
1 (registered trademark). S
ecar51® gives the mortar high resistance to corrosion due to sulfuric acid contained in the water circulating in the sewer system. The life of the lining thus obtained is long and the repair cycle can be minimized.

The Alag® aggregate has a particle size such that it can be mixed with the high levels of particulates of the formulation, and as a result, the formulation can be easily pumped. The adhesion between them is best because their mineral composition is perfectly matched to the mineral composition of the binder. Polypropylene fibers are a means of limiting the phenomenon of separation and shrinkage.

The fly ash promotes the stickiness of the shotcrete and makes it possible to spray a layer with a more remarkable thickness without the risk of collapse of the layer released in place. Sodium citrate is a water reducing additive known in the alumina cement industry. This allows the ratio of water: binder to be controlled to a pumpable mortar, which allows indirect reduction of separation. Methylcellulose J5MS is also a separation inhibitor that promotes pumpability. Click Pack 2 facilitates pumping the formulation.

Table 1 shows other component ratios (% by weight) of the mortar according to the present invention, including other additives, and sieve sizes (particle diameter φ, mm) of the aggregate (fine grains).

Table 1

Example 2 The spray concrete wet method according to the invention. The composition obtained in Example 1 in which the components are mixed in powder form, is from about 12% to about 16% by weight of the dry ingredients measured in the mixer. Preferably about 14% by weight of dilution water is added. The mixer is a concrete mixer having an open container or a concrete mixer having a blade of a suitable size and a water tank for measuring (accuracy ± 1%) mounted on the upper side.

The spray concrete wet method, or "wet spray", requires special equipment with a mixer, concrete pump and additional pump. Usually, this type of equipment can be used in the field, and the operating costs of this method can be reduced. The concrete pump is a pump usually used in the spray concrete wet construction technique, and may be any of so-called P11, P13 or P38 pumps of Putzmeister.

The spray concrete wet method includes the following steps. (I) Mix the flowable mortar obtained in Example 1 with a weighed amount of water in a mixer. (Ii) delivering the mixture to the loading hopper of the concrete pump; (Iii) Pump the mixture via a pipe to a spray nozzle. (Iv) Compressed air and additives are injected into the nozzle for spraying. (V) Spray until a layer of desired thickness is obtained.

Example 3 Performance comparison of mortar according to the invention with conventional mortar Other alumina mortars containing alumina binder mixed with conventional aggregates such as calcium silica and quartz sand available on the market (controls shown in Table 2) Mortar) does not perform as well as the mortar of the present invention, and can therefore cause damage in the field. Further, the formulations of the present invention are of reasonable cost.

Table 2

From each of these mortars, 24 cubes are made and placed in a simulation room to keep the atmosphere supplied with hydrogen sulfide gas. Volume of the simulation chamber is about 1 m ^3, the temperature is adjusted to 30 ° C., relative humidity is maintained at between about 95% to 97%. The gas is injected into a 10 liter vessel to have a H ₂ S concentration of 15 to 20 ppm. Spray a mixture of bacteria every 30 minutes to accelerate the corrosion phenomenon. The cubes are weighed periodically every 8 weeks up to 48 weeks to compare the resulting weight loss. Table 3 shows the results.

Table 3

As can be seen from Table 3, these results demonstrate the excellent and surprising performance of the mortar of the present invention and the remarkable effect of the alumina binder-alumina aggregate combination in particular according to the present invention. That is, at the end of the test period, the weight loss due to corrosion of the mortar of the present invention is reduced by 30% over that of the control mortar.

[0035]

Particularly advantageous mortars according to the invention are:
It is pumpable and sprayable, while at the same time ensuring efficient adhesion to the support to be repaired. In addition, the use of a minimum amount of water allows, on the one hand, the formulation not to separate and, on the other hand, to provide the mixture with sufficient compactness. This improved mortar has excellent mechanical resistance and
In particular, it guarantees corrosion resistance in sulfuric acid-containing water circulating in sewer systems. In addition, it is well adapted and robust to field conditions with diverse environments (temperature, humidity ...). Finally, the mixtures prepared according to the invention have a constant flowability and the mortar has a certain coagulation and setting.

In summary, these capabilities allow for the rapid curing of the mortar of the invention and the very rapid resumption of the sewage system to be repaired thereby, while guaranteeing a high level of resistance to corrosion by wastewater. Therefore, the life of the restored system is extended.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 111: 72 C04B 111: 72 France (72) Inventor Gordley Lauren France 38080 Rière du Vieux Ares de Laurie du Golf 32 (72) Inventor Leteauno Roger France 69740 Jena Impers Louis Renault 15 F-term (reference) 2D063 EA06 4G012 PA11 PD01 PE04

Claims (11)

[Claims] 1. A repair mortar for use in a shotcrete wet method comprising a mixture of a calcium aluminate binder containing at least about 40% by weight alumina and an aggregate of suitable grain size, Aggregate is 1.4m
m or less, wherein at least about 35% by weight of the mixture comprises about 100 μm.
Mortar characterized by having a grain size smaller than m. Wherein said binding material is about 2950 cm ² / g to about 4600cm ² / g, preferably about 4500Cm ²
The mortar according to claim 1, having a Blaine value of / g. 3. The mortar according to claim 2, wherein said binder contains about 53% by weight of alumina. 4. The method according to claim 1, wherein the binder has a C content of less than 0.6%.
Mortar according to claim 3, characterized in that it contains ₁₂ A _7. 5. The method according to claim 1, wherein the binder is obtained by melting in a reverberatory furnace.
The mortar according to any one of the above. 6. The mortar according to claim 1, which contains about 97.7% by weight of calcium aluminate. 7. The method of claim 1, further comprising one or more additives selected from the group consisting of a leakage resistance enhancer, a shrinkage inhibitor, an internal strength enhancer / separation inhibitor and a flowability enhancer. The mortar according to any one of 1 to 5. 8. A mortar-containing concrete composition as defined in any one of the preceding claims wherein the ratio of binder: aggregate is about 1: 1.9, wherein the water / binder is about 0: 1. .
37. A concrete composition characterized by being 37. 9. The method of claim 3, wherein said powder contains about 53% by weight of alumina.
7. Mixing mortar containing 3.7% by weight of binder, about 64% by weight of aggregate and about 2.3% by weight of one or more additives as defined in claim 6 with water. A concrete composition obtained by the process, comprising about 14% by weight of water by dry weight of the concrete composition. 10. A sprayed concrete wet method using the concrete composition according to claim 7. 11. A sewer and drainage system, pipe,
10. The shotcrete wet method according to claim 9, for repairing lining / relining of manholes and related structures.