JPH0688816B2 - Cement quick setting agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Purpose of the invention [Industrial field of application] The present invention relates to a cement quick-setting agent for rapidly setting cement mortar, concrete, etc. The placed mortar and concrete are used as a spraying agent, etc. for the lining of the excavated wall surface in tunnel construction work for roads, railways, sewer pipes, etc. Etc. are widely used.

[Conventional technology]

Conventionally, as a construction method for providing a lining wall on an excavated wall surface of a tunnel or the like, a construction method in which cement, aggregate, a quick-setting agent and water are mixed and rapidly sprayed (spraying construction method) is generally used. As the spraying method, a wet method of mixing a slurry consisting of cement, aggregate and water and a quick-setting admixture solution at the tip of a spray nozzle, a powdery mixture of cement, aggregate and a quick-setting agent and water, or There is a dry method in which a powdery mixture of cement and aggregate and an aqueous solution of a quick-setting admixture are mixed and sprayed at the tip of a spray nozzle.

As the quick-setting agent used in these construction methods, those containing lime aluminate, alkali aluminate, and alkali carbonate as main components are generally used, but the action of quick-setting cement is insufficient, and it was sprayed. It has a problem that a part of the composition falls without curing.

This phenomenon is due to the fact that when the cement and the quick-setting admixture are mixed at the tip of the spray nozzle, the ratio of the cement and the quick-setting admixture varies considerably widely, but the cement quick-setting action of these quick-setting admixtures is And, it is effective only in a narrow range of the ratio of the quick-setting agent, and the quick-setting effect decreases outside the range.

[Problems to be solved by the invention]

As mentioned above, the cement quick setting action of the quick setting agents currently used has a certain range for the cement, for example, 4 to 6
% Is effective in the range of addition, but outside this range, the quick-setting effect is remarkably reduced. Therefore, depending on the skill of the builder, there is a problem that the drop loss of the spray composition reaches 25 to 50% of the whole.

The present inventors have conducted intensive studies to solve the above problems and completed the present invention.

(B) Structure of the Invention [Means for Solving the Problem] The present invention relates to a composition comprising an alkali aluminate, an alkali carbonate, and an organic compound which is hydrolyzed in an alkaline condition to generate an acid. The present invention relates to a cement quick-setting agent, characterized in that the content of alkali carbonate is 0.3 to 5 parts by weight with respect to 1 part by weight of alkali aluminate after deducting the reaction amount of Since the quick-setting admixture is composed of three specific components, it exhibits a fairly constant and good quick-setting action in a wide range of the ratio of cement and the quick-setting admixture, and has the problems that conventional cement quick-setting admixtures have. It was solved all at once.

Constituents Alkali aluminates and alkali carbonates (all of the alkalis are sodium, potassium, lithium, etc., and sodium and potassium are preferred for the present invention) constituting the quick-setting admixture of the present invention are both components of the quick-setting admixture. Although they are known and can be used in the present invention without any trouble, M ₂ O / Al ₂ O is used as an alkali aluminate.
The molar ratio of ₃ (where M = K, Na or Li, etc.) is 1.5 to 3.0.
It is preferable to select one of 1.8 to 2.5
belongs to. The organic compound that hydrolyzes in the third component, alkaline, to generate an acid is methyl acetate,
Monocarboxylic acid esters such as ethyl acetate, polyhydric alcohol fatty acid esters such as ethylene glycol (mono, di) acetic acid ester and glycerin (mono, di, tri) acetic acid ester, methyl glycolate, trimethyl citrate, dimethyl tartrate, malic acid Examples include oxycarboxylic acid esters such as dimethyl, esters such as alkylene carbonates such as ethylene carbonate and propylene carbonate, dialdehydes such as glyoxal and glutardialdehyde, and lactones represented by γ-butyrolactone.

Preparation As the mixing ratio of the three components constituting the quick-setting admixture of the present invention,
First, the amount of alkali carbonate with respect to 1 part by weight of alkali aluminate is 0.3 to 5 parts by weight, preferably 0.5 to 2 parts by weight, and more preferably, from the result shown in Table 6 of Example 4 described later. It is 0.7 to 1.5 parts by weight. It should be noted that the above-mentioned “amount of alkali carbonate with respect to 1 part by weight of alkali aluminate” means, as described in the margin of Table 6, an organic compound which is hydrolyzed in alkaline to generate an acid, for example, ethylene carbonate. It means the amount relative to the value after the reaction, that is, the amount of alkali carbonate with respect to 1 part by weight of alkali aluminate after subtracting the reaction amount with the organic compound from the amount of alkali aluminate in the composition. The blending amount of the organic compound that hydrolyzes to form an acid in the alkalinity of the third component is M ₂ O / Al ₂ O in alkali aluminate after the acid formed by hydrolysis and the alkali metal of alkali aluminate react. Molar ratio of ₃
It is preferable to mix it so as to be 1.2 to 2.0, and more preferable to mix it so as to be 1.3 to 1.7.

In other words, the molecular weight MW of alkali oxide (M ₂ O) not bound to alkali carbonate, its amount W (g), the molar ratio MR of M ₂ O / Al ₂ O ₃ , the equivalent E of the compound, the reaction with the compound When the M ₂ O / Al ₂ O ₃ molar ratio m excluding the alkali oxide Is. In this formula, MR is 1.5 to 3.0, preferably 1.8 to 2.
5, m is 1.2 to 2.0, preferably 1.3 to 1.7.

The alkali aluminate can be obtained, for example, by heating bauxite, aluminum hydroxide or the like and an aqueous alkali hydroxide solution at 60 to 70 ° C or higher. In order to obtain the quick-setting agent of the present invention, first, such an alkali aluminate solution and an alkali carbonate aqueous solution are mixed at a predetermined ratio. Even if the alkali carbonate aqueous solution contains alkali hydrogen carbonate, It does not matter if it contains a small amount of alkali hydroxide.
This step can be performed at room temperature. Although the alkali aluminate and the alkali metal carbonate may be different, it is preferable that they are the same because the solution stability is good. Further, in general, an alkali metal is accompanied with some other alkali metal, but there is no problem in stability at that level.

While stirring the thus obtained mixed solution of alkali aluminate and alkali carbonate, a predetermined amount of the above-mentioned organic compound is added and stirred until a uniform solution is obtained. The temperature in this case may be room temperature, but if dissolution is slow, it is effective to heat to 100 ° C or lower.

The concentration of the product thus obtained is between 30 and 60%,
Select a concentration with good solution stability. For example, in the case of potassium aluminate potassium carbonate, it is 40 to 50%.

In general, the amount of alkali aluminate-based cement quick-setting admixture is 40% to 50% liquid, which is about several percent of the cement, but the case of the present invention's quick-setting admixture is about 2 to 15%. Is preferred,
It is more preferably 3 to 8%, still more preferably 4 to
6%.

For example, as an example of the composition of a dry spraying place, a mixture of 360 kg of Portland cement, 1180 kg of fine aggregate (river sand), 590 kg of crushed stone of 15 mm or less, and the quick-setting agent of the present invention 4
20 kg of 5% solution and 120 of water.

This composition changes intricately depending on the construction purpose, the moisture content of the aggregate, the wet state of the target wall surface, the temperature, the skill of the builder, etc.
It is not fixed at all.

It is also effective to use it in combination with a calcium aluminate type quick-setting agent.

The setting time of cement using a quick-setting agent is JIS R 5201.
It is preferable that the initial time is 1.5 minutes or less and the final time is 5 minutes or less as measured by the method of setting test of Section 7 of "Physical test method for cement". It is preferable to consider the composition.

[Action]

Cement quick-setting agents containing alkali aluminates and alkali carbonates have been known and used for a long time, but as described above, by combining these with an organic compound that produces an acid by hydrolysis, excellent quick-setting performance is achieved. The reason why is expressed is that the acid generated by the hydrolysis of the organic compound reacts with the alkali metal in the alkali aluminate, and as a result, the M ₂ O / Al ₂ O ₃ molar ratio of the alkali aluminate is reduced, and the alkali aluminate is reduced. It is presumed that the molecular weight of is increased and a stable quick setting effect is given to cement.

Moreover, the above-mentioned performance is 2
It can be expressed even in a wide range of up to 15%, and has the effect of reducing loss at the time of spraying.

〔Example〕

Example _{1. K 2 O29.2%, Al 2} O 3 15.8%, the K ₂ O / Al ₂ O ₃ molar ratio of 2.0 aluminate potassium solution 100g, mixture was added 45% K ₂ CO ₃ aqueous solution 100g To the above, 7.0 g of ethylene carbonate was added, and the mixture was heated to about 50 ° C. with stirring and dissolved to obtain a quick-setting agent. 400 g of Portland cement and the amount of cement, 2,5,10,15% of the above-mentioned quick-setting admixture was added to water (110-x) g, and the mixture was quickly mixed and kneaded JIS R5201,7, Physical test of cement Table 1 shows the results of measuring the starting time and the ending time according to the method 7 coagulation test.

Further, in this example, assuming that ethylene carbonate is completely hydrolyzed and reacted with K ₂ O of potassium aluminate, the K ₂ O / Al ₂ O ₃ molar ratio is 1.49.

Comparative Example 1. K ₂ O 26.1%, Al ₂ O ₃ 18.9%, K ₂ O / Al ₂ O ₃ molar ratio 1.49 about a mixed solution of 100 g of potassium aluminate aqueous solution added with 100 g of 45% K ₂ CO ₃ aqueous solution The results of the tests according to Example 1 are shown in Table 2.

Comparative Example 2. According to JP-A-59-156946, a quick-setting agent comprising 25% potassium aluminate, 25% potassium carbonate, and 4% ethylene glycol having a K ₂ O / Al ₂ O ₃ molar ratio of 1.49 was prepared. The results of the tests conducted according to Example 1 are shown in Table 3.

Example 2 Table 4 shows the results of the same test as in Example 1 except that the quick-setting admixture using an organic compound which hydrolyzes with an alkali to generate an acid instead of ethylene carbonate.

Example 3 To a mixed solution of Na ₂ O 19%, Al ₂ O ₃ 16%, Na ₂ O / Al ₂ O ₃ molar ratio 1.95 50 g sodium aluminate aqueous solution 50 g and 7% Na ₂ CO ₃ aqueous solution 150 g, ₃ g ethylene carbonate was added. In addition, it was heated to about 50 ° C to obtain a quick-setting admixture.

Table 5 shows the results of testing the quick-setting admixture in the same manner as in Example 1.

In the present embodiment, when ethylene carbonate was completely hydrolyzed to react with _{Na 2 O Na 2 O / Al} 2 O 3 molar ratio is 1.
52.

Example 4 Table 6 shows the coagulation test results for the quick-setting admixture obtained in Example 1 by changing the amount of the 45% K ₂ CO ₃ aqueous solution to 15 to 700 g. Experiment numbers 1 and 6 correspond to comparative examples.

Example 5 Table 7 shows the test results when the molar ratio of potassium aluminate was changed in Example 1.

Example 6 A mixture of 360 kg of Portland cement, 1180 kg of river sand, 590 kg of crushed stone of 15 mm or less, and the quick-setting agent 2 used in Example 1
As a result of spraying a mixture of 0 kg and 118 kg of water onto the top of the tunnel by the dry method, the loss due to rebound was 10 to 15%, but there was no collapse due to slow curing, and 10 to 10 after spraying. 15
Fully cured in minutes.

Comparative Example _{3 K 2 O26.1%, Al 2} O 3 18.9%, the mixture was added 45% K ₂ CO ₃ aq 100g to K ₂ O / Al ₂ O ₃ molar ratio 1.49 alkali aluminate solution 100g, the A test was conducted according to Example 1 on a liquid prepared by mixing the organic acids shown in Table 8 or salts thereof so that the molar ratio of K ₂ O / Al ₂ O ₃ after the addition of the alkaline aluminate aqueous solution was 1.35. The results are shown in Table 8.

Comparative Example 4 In Example 1, Table 9 shows the result of the coagulation test with respect to the quick-setting agent not using only the 45% K ₂ CO ₃ aqueous solution.

(C) Effect of the invention The quick-setting admixture according to the present invention does not reduce the quick-setting effect even when the mixing ratio to concrete changes drastically. Therefore, it is easy to control the supply rate during construction and sprayed. The concrete is uncured and does not easily collapse. Therefore, the construction speed is high, and the material yield is improved, so that the cost can be significantly reduced.

Claims (1)

[Claims] 1. A composition comprising an alkali aluminate, an alkali carbonate, and an organic compound which is hydrolyzed to form an acid in alkaline conditions, and 1 part by weight of the alkali aluminate after deducting the reaction amount with the organic compound. On the other hand, a cement quick-setting admixture characterized in that the content of alkali carbonate is 0.3-5 parts by weight.