JPS6013987B2 - Auxiliary agent for dry spraying method - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an auxiliary agent for dry spraying, and in particular, its purpose is to significantly reduce "splashing of sprayed material" and ``generation of dust'' in dry spraying. It is something.

Concrete or mortar spraying methods have been widely used in the architectural and civil engineering fields, and there are three types: dry spraying, semi-dry spraying, and wet spraying.

Among these methods, the green spraying method has disadvantages such as the large size of the spraying equipment and the need for power from a large rotary drum, making it difficult to maintain and manage on-site, and it is also difficult to transport the sprayed material over long distances. There is. The semi-dry spraying method also has the same problems as the above-mentioned overflow spraying method, although there are varying degrees of severity. On the other hand, the dry spraying method does not have the disadvantages found in the wet spraying method or the semi-dry spraying method, but on the other hand, it has the following disadvantages: ■ A large rebound rate of the sprayed material during spraying; The problem is that the occurrence is large.

In order to improve these shortcomings of the dry spraying method, studies have been made on the grain size and its distribution, methods for adding water, etc. However, there is no sufficient method to improve the problems of (1) and (2) above. However, this solution was strongly desired.

The present inventor completed the present invention as a result of intensive research in consideration of such technical issues, and this invention consists of 50 to 9 parts by weight of water-soluble cellulose ether, 1 part by weight of water-soluble cellulose ether, and 1 part by weight of water-soluble cellulose ether
Polyethylene oxide 2 to 5 parts by weight Auxiliary agent
1 ~ Male base piece Antifoaming agent
The present invention relates to an auxiliary agent for dry spraying method consisting of 0 to 1 part by weight.

According to the present invention, by adding only a small amount of the above-mentioned auxiliary agent to the material to be sprayed in the dry spraying method, the amount of rebound of the material to be sprayed during spraying can be reduced by three times compared to when the auxiliary agent is not added. This brings about the remarkable effect that the amount of dust is drastically reduced to less than 1, and the generation of dust is also reduced.

The present invention will be explained in more detail below.

The auxiliary agent for the dry spraying method of the present invention is the above-mentioned 'i', 'o'
), each ingredient of shiso and 8 more ingredients as needed,
The main ingredient is [i'
As the water-soluble cellulose ether, water-soluble alkyl cellulose, hydroxyalkyl cellulose, and hydroxyalkyl alkyl cellulose are used.

Among these, especially Hido. xyalkyl・alkyl・
Cellulose is preferable, and its hydroxyalkyl group has 2 to 4 carbon atoms and the degree of molar substitution per trout water glucose unit (
M. S. )0.01-0.5 (preferably 0.03-0
．． 12), and the alkyl group has 1 to 2 carbon atoms and the degree of substitution (D.S.) per anhydroglucose unit is 1.0 to 2.
．． 2 (preferably 1.5 to 2.1). Examples of such hydroxyalkyl alkyl cellulose include hydroxyethyl ethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, and hydroxybutyl methyl cellulose.
Examples include methyl cellulose and hydroxybutyl ethyl cellulose. The reason why the above hydroxyalkyl alkyl cellulose is preferred is as follows.

In other words, alkylcellulose has a low thermal gelation point and does not completely dissolve when applied under high temperature conditions, resulting in a significant reduction in the effect of addition (see Table 3 of Example 3 below).On the other hand, hydroxyalkylcellulose A lot of dust is generated during construction (see Table 2 of Example 2 below). This is probably because hydroxyalkylcellulose has weaker surface activity than hydroxyalkyl-alkylcellulose, or because it lacks the strong gel strength characteristic of alkoxy group-containing cellulose. In contrast, hydroxyalkyl alkyl cellulose shows excellent effects in all respects. Examples of water-droppable alkylcellulose include methylcellulose and ethylcellulose with a special degree of substitution, and examples of hydroxyalkylcellulose include hydroxyethylcellulose, hydroxypropylcellulose, and hydroxybutylcellulose.

The water-soluble cellulose ether used as the component used in the present invention preferably has a viscosity of 15 to 10 centipoise (particularly 500 centipoise or more) at 2 psi of a 2% aqueous solution; Shotcrete (or mortar) if it is of viscosity
It is undesirable because the adhesion to the arm surface is weak, the rebound rate is high, and more dust is generated.

Next, [o] polyethylene oxide, which is used together with the {i' component, has a unique viscosity and leakage property, and is used to improve the flow of the sprayed material in piping or nozzles. , and its characteristics can be utilized by combining it with the 'i component.

The desirable molecular weight of this component [〇] is from 500,000 to 500,000. As mentioned above, this raw component is used in an amount of 2 to 5 parts by weight compared to 50 to 9 parts by weight of the raw component. , no effect of reducing the rebound rate was observed, and if the component {〇} exceeds 50 parts by weight, not only would it be difficult to spray from a nozzle due to its high viscosity, but the rebound rate would also be insufficiently sticky. Good results are not bound.

Examples of water reducing agents include those whose main component is lignin sulfonate, those whose main component is polyoxyethylene alkylaryl ether, those whose main component is polyol complexes, and aromatic polycyclic condensates. Examples include those whose main component is a sulfonate of water-soluble melamine-formalin resin (methylol melamine), and these are used for the purpose of improving the wetting of cement particles. The above-mentioned 'i' and [o- components are used in an amount of 1 to 2 parts by weight based on the amount used.

If this amount is too small, the above purpose (effect) will not be achieved, and if it is more than the cloud amount part 2, it will cause a retarding effect on cement setting, reduce the initial strength of shotcrete, weaken the adhesion force, and increase the bounce rate. This gives rise to the problem of becoming. The auxiliary agent of the present invention is composed of the above-mentioned components, but if necessary, an antifoaming agent may be added in an amount of 1 part by weight or less, and as this antifoaming agent, Examples include polyoxyethylene-bolyoxypropylene block copolymers resistant to alkalinity, nonionic special compounds, higher alcohols, tributyl phosphate, and silicones.

In the dry spraying process of concrete or mortar, the auxiliary agent of the present invention can be used either by dry blending it with cement, aggregate, etc. or by dissolving it in added water in advance, but the latter method is more uniform. Preferable in terms of mixing.

Further, it may be mixed in advance and added to a steepening agent used for shotcrete, and the steepening agent in this case may be either a powdered one or a liquid one. Not only when dissolved and added to a liquid quick-setting agent, but also when premixed and added to a powdery quick-setting agent, relatively uniform mixing can be expected. The amount of auxiliary agent used is 0.02 to 1.0% of cement for concrete or mortar. (particularly 0.1% by weight)
~0.5% by weight). If the amount used is too large, the viscosity of the concrete or mortar will increase, making it difficult to spray, delaying the setting of the cement, weakening the adhesive force, and increasing the bounce rate, so care must be taken. Next, specific examples will be given.

However, the following cellulose edel was used. HE-1: hydroxyethyl methylcellulose,
Degree of substitution of hydroxyethyl group (M.S.)=0. Female, degree of methyl substitution (D.S.) = 1.8, viscosity of 2% aqueous solution at 20 qo, 4000 centipoise.

HE-2: The degree of methyl group substitution (D
．． S. )=1.5.

HE-3: Same as HE-1 except that the degree of hydroxyethyl group substitution (D.S.) was 1.2.

HE-4: The same as HE-1 except that the degree of hydroxyethyl group substitution (D.S.) was 0.02.

HE-5: Same as HE-1 except that the degree of hydroxyethyl group substitution (D.S.) was 0.05.
HE-6: The same as HE-1 except that the degree of hydroxyethyl group substitution (D.S.) was 0.15.
HP-1: Hydroxypropylene methylcellulose,
Degree of substitution of hydroxypropyl group (D.S.) = 0.08
Methyl group substitution degree (D.S.): 1. &2 of 2% aqueous solution
Viscosity 4000 centipoise at 0°C.

HP-2: The degree of methyl group substitution (D
．． S. )=1.5.

HP-3: Same as HP-1 except that the degree of hydroxypropyl substitution (D.S.) was 1.2.

HEC: Hydroxyethyl cellulose, degree of hydroxyethyl group substitution (M.S.) = 2.0, 2% aqueous solution
Viscosity 4000 centipoise at 0°C.

MC: Methyl cellulose, degree of methyl group substitution (D.
S. ): 2.0, viscosity of 2% aqueous solution at 20°C 40
00 centipoise.

Example 1 Cellulose ether, polyethylene oxide (5% aqueous solution with viscosity of 100 centipoise at 25°C)
, a lignin sulfonate-based water reducing agent, and an alcohol-based antifoaming agent were blended as shown in Table 1.

This mixture (spraying aid) is applied to the shotcrete first.
Concrete was sprayed using the dry spraying method by adding the ingredients in the proportions shown in the table.

At this time, the spraying aid was dissolved in water and added through the water ring at the same time as the water. [Concrete mix] The maximum size of coarse aggregate is 2 broadsides, the water/cement ratio is 40%, the pongee aggregate ratio (S/A) is 60%, and the unit amounts are as follows.

[Spraying test]

Using Ariba 260 type as a spraying machine, the construction temperature was 2 pm.
The dust generation was visually observed, and the repulsion rate was measured.

In addition, the compressive strength of concrete at 28 days old was determined. The results are shown in Table 1.

Table 1 (Note 1) Percentage of cement. (Note 2) A (less) < B < C < ○ (more) (Sound B) Indicates parts by weight.

*Comparative Experiment Example 2 Various cellulose ethers were used (second
Table) The same polyethylene oxide, lignin sulfonic acid-based water reducing agent, and alcohol-based antifoaming agent as in Example 1 were used in the previous experiment &. It was blended in the same proportion as 1.

A spraying experiment was conducted in the same manner as in Example 1 using the method of adding the spraying aid, concrete formulation, spraying machine, etc., and the dust generation, rebound rate, and compressive strength of the concrete were measured.

The results are shown in Table 2. However, the amount of spraying aid used in the same table is expressed in percent by weight relative to cement. Table 2 (Note) HRI/R2=hydro.

Kinarchyl based M. S. )/alkyl group D. S. )
Example 3 The same polyethylene oxide, lignin sulfonic acid water reducing agent, and alcohol antifoaming agent as in Example 1 were used in Experiment M, except that various cellulose ethers were used (Table 3). ．． It was blended in the same proportion as 1.

The method of adding the spraying agent, concrete mix, spraying machine, etc. were the same as in Example 1, and the construction temperature was 0 or 20℃, and a spraying experiment was conducted to determine the dust generation status, rebound rate, and concrete compressive strength. was measured.

The results are shown in Table 3. However, the amount of spraying aid used in the same table is expressed in percent by weight relative to cement.

Table 3 Example 4 Comparison of the methods of adding the spraying aid: directly adding the powder to the cement or bone mound, adding the powder by mixing it with the powdered quickener, and adding it by dissolving it in the liquid quickener. I did it.

The spraying aid was the experimental site of Example 2. Use the same thing as 10,
Ta.

A spraying test was conducted using the same concrete mix, spraying machine, etc. as in Example 1, and the dust generation, rebound rate, and concrete compressive strength were measured. The results are shown in Table 4.
The amount of spraying aid used in the same table is expressed in percent by weight relative to cement.

Table 4

Claims (1)

[Claims] 1 (a) 50 to 90 parts by weight of water-soluble cellulose ether, (b) 2 to 50 parts by weight of polyethylene oxide (c)
An auxiliary agent for a dry spraying method consisting of 1 to 20 parts by weight of a water reducing agent (d) and 0 to 10 parts by weight of an antifoaming agent. 2. The water-soluble cellulose ether has a hydroxyalkyl group substitution degree of 0.01 to 0.5 and an alkyl group substitution degree of 1.
The auxiliary agent for dry spraying method according to claim 1, which is a hydroxyalkyl alkyl cellulose ether having a molecular weight of 0 to 2.2.