JPS6221510A - Manufacture of mortar or concrete - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

TECHNICAL FIELD The present invention relates to a method for producing mortar or concrete, particularly mortar or concrete suitable for spraying.

(Prior art) Conventionally, in order to obtain concrete for use in blowing, a viscous liquid consisting of an aqueous solution of a polymeric substance was added to the aggregate, and after stirring and mixing them, cement powder was further added. A method has been proposed in which the cement powder is attached to the aggregate via the viscous liquid by stirring and mixing, and the water is removed (Japanese Patent Laid-Open No. 143098/1983).

According to this method, due to the action of the viscous liquid adhering to the aggregate, the separation of cement powder from the aggregate can be reduced compared to the case where the viscous liquid is not added. The amount of dust generated at the time is reduced.

However, in this method, since an aqueous solution is further added to the aggregates having surface water, the concentration of the aqueous solution that adheres to the aggregates, that is, the sticky liquid, is lower than that before addition, and the concentration of the sticky liquid is lower than that before addition. The set may exceed the total amount of aggregate that can be held on its surface. Further, in order to cover the surface of the aggregate with the viscous aqueous solution, it is necessary to add the aqueous solution in the form of a mist, but the concentration that can be made into the atomized form is relatively low.

For this reason, the adhesion strength of the cement powder to the aggregate via the viscous liquid must be relatively low.

For this reason, in wet concrete spraying, after concrete I is supplied to the spraying device, the flow resistance of the concrete in the concrete material hose due to compressed air becomes extremely high, making it difficult to pump and spray the concrete. It may be impossible.

In addition, in dry concrete spraying, when the aggregate to which cement powder is attached is conveyed through the material hose using compressed air, the adhesion strength is relatively small, so that the cement powder is transferred to the aggregate during conveyance. It is easy to peel off from the concrete, which reduces the quality of the concrete and increases the amount of dust.

Furthermore, according to this method, due to the influence of the polymeric substance,
Despite the required amount of water being added to the concrete, concrete is produced that has poor fluidity.

(Objective of the Invention) An object of the present invention is to provide a method for producing mortar or concrete that can suppress separation of cement particles and fine aggregate particles by increasing the adhesion of an adhesive film covering aggregate. be.

(Structure 1 of the invention) The present invention provides an adhesive coating that covers a large number of aggregates by dissolving a powdery polymeric material having hydrophilic properties in the surface water of a large number of aggregates covered with surface water. The basic concept is to form a cement layer that covers the adhesive film by attaching cement particles to the adhesive film, and to mix the aggregate covered with the cement layer with water. do.

According to the present invention, since the adhesive film covering the aggregate is formed by dissolving a powdery polymeric material in the surface water covering the aggregate as a solvent, the adhesive film is made to have a high concentration. be able to. As a result, mortar or concrete is obtained in which cement particles are firmly attached to the surface of the aggregate.

When the resulting mortar or concrete is used for wet spraying, there is less pulsation within the material port and the amount of dust generated is reduced. Furthermore, the concrete thus obtained maintains a strong bond between the aggregate and cement particles even when placed in water.

The present invention also provides for supplying the aggregate covered with the cement layer to a spraying device and transporting the aggregate covered with the cement layer in the material hose of the spraying device while conveying the aggregate covered with the cement layer by means of compressed air in the material hose of the spraying device. and water.

According to the present invention, since the cement particles are firmly bonded to the aggregate through the highly concentrated adhesive film,
During the conveyance of aggregate with a cement layer in the material hose by means of compressed air, separation of the cement particles from the aggregate by the compressed air can be minimized. For this reason, dry spraying can significantly reduce the amount of dust generated.

(Example) In the method for producing mortar or concrete according to the present invention, first, a powdery polymeric material having hydrophilic properties is dissolved in the surface water 12 of a large number of aggregates 10 covered with surface water. to form an adhesive film 14 covering the aggregate io (first
(see Figures and Figure 2).

The aggregate 10 is fine aggregate when manufacturing mortar, and
Fine and coarse aggregates are used in making concrete. Examples of the fine aggregate and coarse aggregate include sand and gravel, respectively.

The amount of surface water of the sand in the case of mortar production is determined by the surface water ratio [=(weight of water attached to the surface of aggregate)/(weight of aggregate in surface dry saturated state) x Zoo] from 2 to 8 It's surprising.

In addition, in the case of concrete production, the ratio of the surface water of the sand is 2 at the above-mentioned surface water rate, as in the case of mortar production.
~8z, and it is desirable that the surface of the gravel is not dry but in a wet state (for example, the gravel has a maximum particle size of 13+am and the surface moisture content is about 2χ).

In addition, in the production of both mortar and concrete, the lower limit of the surface water content of the sand is the solubility limit of the polymer material, and also the ease of dissolution of the polymer material and the resulting tackiness. Considering the viscosity of the material III 14, it is most preferable that the surface water content is in the range of 4 to 7z.

In order to dissolve the powdered polymeric material in the surface water 12 of the aggregate 10, for example, the aggregate 10 is placed in a mixer (not shown), and while stirring, the polymeric material is sprinkled. The mixture is then placed in the mixer. Due to the stirring action of the mixer, the polymeric material is dissolved in the surface water 12 of the aggregate 10 as a solvent, and the surface of each aggregate 1O is covered with an adhesive film 14. At this time, the polymer material rubs against the aggregate 10, so the solute (water) is simply added to the solvent (water).
Compared to the case where a polymeric material (polymer material) is added and stirred, a solution, that is, an adhesive film 14 can be formed by using short poem nR.

Note that when a polymer material is added to water and stirred to obtain a solution, it takes several minutes to several hours for the polymer material to dissolve, depending on the components and molecular weight of the polymer material. When the dissolution time is shortened, flocs are formed that are condensed into a jelly-like powder or jelly that does not have adhesive properties.

However, in the present invention, the polymer material can be dissolved in the surface water 12 in a short time without generating the powder or flocs.

Examples of the powdery polymeric material include those that exhibit adhesive properties when dissolved in water, such as water-soluble cellulose ether, whose added weight is 12% of the surface water.
The amount may be about 1.0 to 6.5z. Also,
The stirring time is 3 when using a double-screw horizontal forced mixer.
It may be 0 to 80 seconds.

The concentration of the adhesive film 14 thus formed is 1%.
It has a high concentration of more than

Next, cement particles 1 are applied to the adhesive film 14 covering the aggregate 10.
6 is deposited to form a cement layer 18 covering the adhesive coating 14.

The cement layer 18 can be formed using the biaxial horizontal forced mixing mixer. That is, when a predetermined amount of cement is put into the mixer while the aggregate lO covered with the adhesive film 14 is stirred in a biaxial horizontal forced mixer, the cement particles 16 become sticky due to the stirring action of the mixer. It strongly adheres to the surface of the sticky film 14 without any gaps, and absorbs moisture from the adhesive film 14 (see FIG. 2).

The stirring time at this time may be 30 to 90 seconds. In this way, a cement layer 18 that is difficult to separate from the aggregate 10 is formed. Incidentally, fine particles of aggregate lO are also adhered to the adhesive film 14 together with the cement particles.

Thereafter, water is supplied in the required amount per unit to the aggregate 10 on which the cement layer 18 has been formed, and the aggregates 10 are mixed. As a result, the cement particles 16 absorb some of the water, and the aggregate lO covered with the cement layer 8 passes through the water.
touch each other. Mortar or concrete is thus produced.

When the aggregate lO is mixed with water, the cement layer 18 is firmly attached to the surface of the highly viscous adhesive film 14 covering the aggregate 10, so very few cement particles 16 are separated from the aggregate lO. .

The mortar or concrete of the present invention is particularly useful when used for spraying or underwater pouring.

When wet spraying is used for concrete applications, the quick-setting agent is added prior to feeding into a concrete spraying device (not shown) or during pumping of the material through the material hose of said spraying device. Even though concrete contains a highly viscous sticky substance, there is little pulsation or increased flow resistance within the material hose. In addition, even after being formed into concrete, the cement particles 16 remain firmly bonded to the adhesive coating 14, so that there is less separation of the cement particles 16 during the pressure feeding and spraying, resulting in less dust generation. Quantity is small.

Further, when used as underwater concrete, the amount of cement particles 16 separated even in water is small due to the strong bonding of cement particles 16 to adhesive coating 14.

As shown in FIG.
It can be done inside.

The aggregate on which the cement layer 18 has been formed is sprayed by a spraying device 20.
After being supplied to the material hose 22 , the material is conveyed to the side of the spray nozzle 24 using compressed air as a conveyance medium through the material hose 22 having a spray nozzle 24 at its tip. Water W can be injected into the material hose 22 at any position in its longitudinal direction. In the material hose 22, the aggregate lO and water W are mixed by the action of the compressed air to produce mortar or concrete.

The dry spray mortar or concrete thus produced is then ejected from the spray nozzle 24 onto the spray surface 26 . The quick-setting material can be added in a powder state to the aggregate 10 before being supplied to the spraying device 11t20, or in a liquid state to the aggregate 10 being pumped. Even when this dry spraying is used as mortar or concrete, the separation of the cement particles 16 is significantly suppressed when the aggregate 10 on which the cement layer 18 has been formed is conveyed in the material hose 22 and when it is sprayed, so that the cement particles 16 are not dispersed. is also suppressed, and the amount of dust generated is significantly reduced.

In order to investigate the characteristics of the concrete according to the present invention, (I) cement separation test and (II) dry spraying concrete test were conducted and compared between two types of conventional concrete and the concrete of the present invention.

The conventional concretes used in the test were ordinary concrete, concrete with an aqueous polymer compound added (an aqueous solution in which a polymer material was dissolved was added to the aggregate to cover its surface, cement was attached to this, and concrete was added with an aqueous solution of a polymer compound. (concrete formed by adding) was used.

(1) Cement separation test 11 units: unit amount of cement: 380Kg, water/cement: 5
B, 5 weight 2, sand/(sand gravel) = 65 weight 2, maximum diameter of gravel: 13 mm -min H' Cement amount per unit of added concrete: 380 Kg, water/cement: 58.5 weight %
, sand/(sand gravel) = 65 weight 2, maximum diameter of gravel: 13
■, Polymer material: 1.08Kg (a polymer compound whose main component is methylcellulose) Tom Clean No.
, 3B, manufactured by Shin-Etsu Chemical Co., Ltd.), Amount of water in which the polymer material is dissolved: 501 shots of the weight of water Amount of cement per unit of concrete: 380Kg, Water/cement: 5
9.5 weight 2, sand/(sand gravel) 265 weight 2, maximum diameter of gravel: 13mm, polymer material: 1.08Kg (
The same Natom Clean No. 3B) Test method A 5001 capacity measuring cylinder containing 200 ml of water and 400 g of concrete was inverted M times under -L, and then left to stand for 10 minutes.

As a result of the test, water, cement, and aggregate were separated into layers in the graduated cylinder. The volume of the cement layer at this time was as follows.

Ordinary concrete): ? 3+*I (-th) 701
(Second time) Concrete with addition of polymer compound aqueous solution: 611 (-th time) 571 (Second time) Concrete of the present invention: 351 (-th time) 401 (Second time) From these results, it can be seen that the concrete according to the present invention has the ability to absorb cement in water. It can be seen that there is little separation of the concrete, making it useful as concrete for underwater pouring.

(TI) Concrete test test method for dry spraying Concrete was sprayed in a simulated tunnel with a length of 22 m and a volume of 14 m2 that was closed at both ends. Measurements were made using a digital dust meter (Model P-5L2, manufactured by Shibata Kagaku Kikai Kogyo Co., Ltd.) at a distance of 5 m from the nozzle of the spraying device (Aliper 280). Concrete is sprayed by adding a powdered quick-setting agent to the concrete material in the form of a dry mix mixed using a twin-shaft forced line mixer and feeding it to the spraying device using a belt conveyor. This was done by adding water to the concrete material while conveying it with compressed air.

The mix of concrete used is as follows: Concrete cement amount: 3EiOKg, sand/(sand/gravel): 6
5% by weight, maximum diameter of gravel: ] 3 layers, quick-setting agent amount: Cement amount Noah% (25,2Kg) Separation ° Addition ■Concrete Cement amount: 380Kg, Sand/(Sand + Gravel): 65
Weight 2, maximum diameter of gravel = 131 layers, amount of quick setting agent: amount of cement (25.2Kg), amount of polymer material added:
Concrete of 1-08Kg (Natom Clean No. 3B, a polymer compound containing methylcellulose as a main component, manufactured by Shin-Etsu Chemical Co., Ltd.) The formulation is the same as the above-mentioned concrete containing an aqueous solution of a polymer compound.

Test results Dust concentration of ordinary concrete: 878 cp layer (average of 5 times) Dust concentration of concrete added with aqueous polymer compound solution: 2
88 cpm (same, h) Dust concentration of concrete of the present invention: 15? cp■ (same) This result is believed to indicate that the concrete of the present invention exhibits less segregation of cement particles within the material hose than conventional concrete.

In addition, a polymer compound whose main component is methylcellulose
When the amount of Natom Clean No. 3B added is 1.8 Kg, and when another polymer material (Silybon 5PR-8 Fuji Bussan ■, a polymer compound whose main component is methyl cellulose) is used, and its weight is 1.8 Kg, the weight is 1.8 Kg. Dry spraying of the concrete of the present invention at 8 Kg was related to the concrete test and the test results were as follows.

Dust concentration/fist/83 cpm for Natom Clean 3B
(Average of 3 times) Dust concentration for Siripon 5PR-8 ---Vllc
P layer (same as above) These results show that by increasing the amount of polymer material added to increase the concentration of the adhesive film, the separation and dispersion of cement particles can be further suppressed.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of one aggregate covered with surface water, Figure 2 is a cross-sectional view of one aggregate covered with a cement layer, and Figure 3 is a cross-sectional view of one aggregate covered with a cement layer.
The figure is a schematic overall view of the spraying device. lO: aggregate, 12: surface water, 14: adhesive film, 16: cement particles, 18: cement layer,
20: Spraying device, 22: Material hose. Agent Patent Attorney Nobuyuki Matsunaga Figure 1 Figure 2

Claims (7)

[Claims] (1) Dissolving a hydrophilic powdered polymeric material in the surface water of a large number of aggregates covered with surface water to form an adhesive film covering the aggregates; A method of making mortar or concrete comprising depositing cement particles to form a cement layer covering the adhesive coating, and then mixing aggregate covered with the cement layer with water. (2) The method according to claim (1), wherein the aggregate is made of fine aggregate, and the surface water content of the fine aggregate is 2 to 8%. (3) The method according to claim (1), wherein the aggregate consists of coarse aggregate and fine aggregate. (4) Claim No. 1, wherein the weight ratio of the polymer material to the surface water of the aggregate is 1.0 to 6.5%.
The method described in section. (5) The method according to claim (1), wherein the polymer material is dissolved in the surface water by stirring the aggregate and the polymer material. (6) The method according to claim (1), wherein the cement layer is formed by stirring the aggregate covered with the adhesive film and cement. (7) dissolving a hydrophilic powdered polymeric material in the surface water of a large number of aggregates covered with surface water to form an adhesive film covering the aggregate; depositing cement particles to form a cement layer covering the adhesive coating; supplying the aggregate covered with the cement layer to a spraying device and transporting it through a material hose of the spraying device via compressed air; A method for producing mortar or concrete, comprising, in between, mixing aggregate covered with said cement layer with water in said material hose.