JPS6192262A - Method for spraying cement mortar or concrete - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention sprays cement mortar or concrete on the ceiling or wall of a tunnel, hardens it instantly without giving any room for flaking off due to its own weight, and This invention relates to a cement mortar or concrete spraying method that does not reduce long-term strength.

[Prior art]

Conventionally, as a spraying method, a dry spraying method in which a dry-mixed spraying material to which a quick-setting agent has been added is sprayed together with water has been put into practical use. On the other hand, the wet spraying method, which uses mortar and concrete materials without the addition of quick-setting agents, is also used mainly on slopes. The wet spraying method uses fluid mortar or concrete that has been pre-added with water, so it has the advantage of generating less dust (and less rebound), but if a quick-setting agent is added, the rapid setting makes it impossible to work. In addition, even if it could be added to a workable level, fluidity was particularly required for the mortar or concrete to be pumped.
It was necessary to increase the cement/water ratio by about 5 to 20% higher than in the dry method.

[Problem that the invention seeks to solve]

With quick setting agents that have low quick setting power, or with conventional quick setting agents that can hardly be expected to have quick setting power immediately after addition depending on the amount added, it is difficult to use quick setting agents that can be used on tunnel ceilings or even on slopes where spring water is sprayed. In areas where even a small amount of water is present, the spraying material flows out, making spraying impossible.

Therefore, it can be applied to ceiling areas and spring water areas,
Moreover, there was a need for a spraying method that did not generate much dust.

[Means of problem solving]

The present invention provides an alkali carbonate of 95 to 50% for cement.
It is characterized in that an quick-setting agent consisting of 5% to 50% by weight of calcium aluminate is added to the fluid mortar or concrete immediately before spraying.

Examples of the alkali carbonate used in the present invention include sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, etc. Among them, anhydrous sodium carbonate can conveniently achieve the intended purpose. In addition, as calcium aluminate, Ca 0 ・2 Altos, Ca
0-Altos, 12Ca 0 ・7 Alx
03.3 CaO・A4′ZO3 and 3′Ca0・3AlzOs・CaFt in which halogen elements are dissolved in solid solution
.

11CaO・7A6Ch-caFt etc. are used, but
Among them, 12Ca 0 ・7 AlzOx, IICa 0
・7 Alz(h・Ca F t has excellent rapid setting properties.Furthermore, when producing these calcium aluminates, an amorphous product can be obtained by rapidly cooling the melt, but this product is a crystalline product. An amorphous one is preferable because its rapid setting property is three times greater than that of calcium aluminate.The finer the powder size of calcium aluminate, the greater its rapid setting property, but a plain value of 1000 aJ/g is sufficient.

The ratio of alkali carbonate and calcium aluminate is about 95 to 50% by weight of alkali carbonate and 5 to 50% by weight of calcium aluminate, especially 90 to 70% by weight of alkali carbonate, from the viewpoint of imparting rapid setting properties. and calcium alumina) from 10 to 30% by weight.

The amount of this quick-setting agent is 3 to 20% by weight based on cement.
The amount is about 5 to 12% by weight, preferably 5 to 12% by weight. If it is less than 31% by weight, it will be difficult to set quickly, and if it is more than 20% by weight, the long-term strength of plain concrete will be less than 50%, which is not preferable.

It is preferable that the fluid mortar and concrete used have a large slump in consideration of the pumping capacity, but if the slump is increased by increasing the amount of water, the amount of quick setting agent used will increase, so a water reducer, especially a high performance water reducer, is recommended. It is preferable to use a formulation that uses less water to improve fluidity, with a slump of about 5 to 15 ca+, and a water/7 ment ratio of 65 to 5.
About 5% is preferable.

The quick-setting agent is added immediately before spraying, and for example, an air-pressure-feeding quick-setting agent blower may be used.

The blowing location is preferably several meters to several tens of meters in front of the nozzle for a good balance of mixing properties, adhesion properties, clogging properties, etc.

[Example 1] Plain 3800cd/g 12Ca 0 7 A
lzCh and anhydrous sodium carbonate were mixed at a weight ratio of 20/80 to prepare an quick setting agent.

Ordinary Portland cement (electrochemical industry side) 360
Parts by weight, 1300 parts by weight of sand, 550 parts by weight of gravel, 21 parts by weight of water
Add 6 parts by weight and 3.6 parts by weight of a β-naphthalene sulfonate-based high performance water reducer, and in? Knead 5 times in a batcher plant and mix 5N of ready-mixed concrete with a slump of 12cm.
? I got it. This concrete was transported to the tunnel face using a mixer truck and sprayed using an Aliper 280 type spraying machine (manufactured by Aliper ■). At this time, the above-mentioned quick-setting agent was blown into the cement using a pneumatic method so that the concentration was 5.7.9% based on the cement.
Each was added by blowing into a concrete pressure hose using ffl (trade name: Natomcrete, manufactured by Sugijodatsuki ■).

As a result, it was possible to perform construction with less rebound and an extremely small amount of dust. In addition, construction was possible in areas with spring water by increasing the amount of quick-setting agent added.

For comparison, a commercially available quick-setting agent consisting of sodium aluminate and soda carbonate was added to the cement at a rate of 3.5.8.10%.
Construction was carried out by adding each of them so that the following amounts were added, but peeling of the concrete occurred regardless of the amount added, and especially in the ceiling part, peeling started when the thickness reached several CN+ or more, making construction impossible. Moreover, when the amount added was increased, the rapid setting power tended to decrease, contrary to the present invention.

[Example 2] Using the quick setting agent of Example 1, Himeyo natural sand (FM2.
47) Ordinary Portland cement 70 to 2000 g
0 g was added and kneaded for 3 minutes using a mortar mixer to obtain a fluid mortar. A quick setting agent was added to this mortar at a ratio of 5.7.9% to the cement.
The mixture was mixed for 20 seconds, packed in a mold, and the resistance to blocker penetration was measured. The results are shown in Table 1. Further, for comparison, similar tests were conducted using the commercially available quick-setting agent described in Example 1, and the results are also listed in Table 1.

[Effects] - The present invention has made possible a spraying method that can be applied to ceiling areas and spring water areas, and is less likely to generate dust.

Table 1

Claims (1)

[Claims] Shotting of cement mortar or concrete, characterized in that a rapid setting agent consisting of 95 to 50% by weight of alkali carbonate and 5 to 50% by weight of calcium aluminate is added to fluid mortar or concrete immediately before spraying. Law.