JPS6328864B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention mainly relates to an quick-setting agent used in shotcrete construction methods. Most of the materials conventionally used as this type of quick-setting agent are alkali metal carbonate salts, alkali metal aluminate salts, or mixtures thereof, or quick-setting cement minerals such as C ₁₂ A ₇ and CA. The supply form is roughly divided into powdered products and liquid products, and most of the commercially available products are powdered products. However, these powdered quick-setting agents are mixed with cement and aggregate before being sprayed with a spraying device, so if the aggregate contains a lot of surface water, it may react with this water. The kneaded material often condenses in the hoses and nozzles of spray equipment, causing blockages. Furthermore, if a large amount of water is present, such as by spraying on a wall with a lot of spring water or by adding too much water, there is a drawback that the quick-setting power is greatly reduced. If the quick-setting force is not sufficiently exerted, the concrete obtained by spraying may fall off, which is dangerous and will significantly delay the construction work. Further, the quick-setting ability of the above-mentioned conventional quick-setting agents is greatly affected by temperature, and they often show almost no quick-setting effect, especially in cold regions in winter.
Although quick-setting agents made from fired cement generally have excellent quick-setting properties, they are easily affected by the surface water of the sand mixed as aggregate, and in reality, they are not suitable for achieving excellent quick-setting effects. There are few cases where suitable on-site construction conditions can be obtained. The present invention aims to improve these conventional drawbacks, and its main feature is to further add a polyhydric alcohol to a mixture of aqueous alkali metal aluminates and alkali metal carbonates. As mentioned above, it is a well-known fact that alkali metal aluminates and alkali metal carbonates are used together as a cement quick-setting agent. When the present inventors further added a polyhydric alcohol to a mixture of alkali metal aluminates and alkali metal carbonates, surprisingly, the effect of temperature on the rapid setting effect was almost eliminated, and the resulting concrete The present invention was completed by discovering that the strength is also improved compared to the conventional one. The present invention will be explained in detail below. The quick setting agent for shotcrete of the present invention includes 20 to 60% by weight of alkali metal aluminates, 10 to 50% by weight of alkali metal carbonates, and 0.1% of polyhydric alcohols.
~10% by weight of the mixture. The alkali metal salts of aluminate used in the present invention are alkali metal salts of aluminate, that is, alkali metal salts such as potassium, sodium, and lithium;
More preferred is potassium salt. The above-mentioned alkali metal aluminate salts are usually provided as a 10 to 70% by weight aqueous solution. The alkali metal carbonate salts used in the present invention are alkali metal salts of carbonic acid, ie, alkali metal salts such as potassium, sodium, and lithium, and more preferably potassium salts. The polyhydric alcohols used in the present invention are ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, ethanediol, propanediol, butanediol, glycerin, propanetriol, butanetriol, pentaerythritol, diethanolamine , triethanolamine, dipropanolamine, tripropanolamine, and other alcohols containing two or more hydroxyl groups per molecule, including substituents such as alkanolamines. The above components are mixed within the above composition range. When all the components are mixed into one solution, a product with very good stability can be obtained if both the alkali metal aluminate salt and the alkali metal carbonate salt are potassium salts. If the above composition contains alkali metal aluminate salts at 20% by weight or less, the rapid setting required in the shotcrete method will not be satisfied, and if the content exceeds 60% by weight, it will not dissolve uniformly in water. This produces insoluble matter. Furthermore, when the alkali metal carbonate salts are contained in an amount of 10% by weight or less, the rapid setting promotion effect is not significant within the composition range of the alkali metal aluminate salts mentioned above, and if the alkali metal salts are contained in an amount of 50% by weight or more, they dissolve uniformly in water. It does not produce insoluble matter. Furthermore, if the polyhydric alcohol is contained in an amount of 0.1% by weight or less, the effect of the addition is not significant, and if it is contained in an amount of 10% by weight or more, it inhibits the development of the initial strength of the concrete. Furthermore, the preferred composition range of the cement quickening agent of the present invention is 30 to 50% by weight of alkali metal aluminate salts;
The content is 20 to 40% by weight of alkali metal carbonate and 1 to 7% by weight of polyhydric alcohol. The cement quickening agent of the present invention is usually provided in the form of an aqueous solution, and is added in an amount of about 1 to 20% by weight, preferably about 4 to 8% by weight, based on the cement. Example 1 Mortar was cured using the cement quick-setting agent of the present invention having the composition shown in Table 1, and the setting and hardening time was measured by the Proctor penetration resistance method (ASTM C403-63T). The blocks used in the test were created as follows. (1) Mortar composition Cement: Ordinary Portland cement Sand: FM2.8 surface water 7% Cement-sand ratio: 1:4 Water-cement ratio: 50% Accelerating agent addition amount: 6% by weight/cement (2) Test block Creation method: After dry-mixing cement and sand with a mortar mixer, a pre-mixed mixture of water and cement quick-setting agent was added, followed by low-speed kneading for 5 seconds and then high-speed kneading for 5 seconds. Create a test block by quickly tamping the material in a mixer ball. Test The penetration resistance of the above test block was measured using a Proctor penetration tester at 20°C. The measurement results of penetration resistance are shown in Table 2. Second
In the table, the compositions of the quick setting agents used in Comparative Examples 1, 2, and 3 are shown in Table 3.

【table】

[Table] Here, EG stands for ethylene glycol.
TEA is triethanolamine, PG is propylene glycol, Gn is glycerin, DIPA is diisopropanolamine, and TIPA is triisopropanolamine.

【table】

[Table] According to Table 2, the mortars to which cement quick-setting agents were added in test Nos. 1 to 11 according to the present invention exhibited greater penetration resistance from the beginning compared to the comparative examples, and the quick-setting agents were significantly more effective. It is understood that it is excellent in especially exam
Comparing No. 2 and Comparative Example 1, it is clear that the effect of adding TEA is greater. In this test, as mentioned above, the surface water of the sand used in the test block was large (7%), so during dry kneading, the surface of the cement particles caused a hydration reaction with the surface water, resulting in a so-called cold catching condition. Although the quick-setting properties are considerably impaired due to the above-mentioned conditions, excellent quick-setting properties were nevertheless observed in Test Nos. 1 to 11 as described above. Example 2 Proctor penetration resistance is measured in the same manner as in Example 1 at various temperatures using the test blocks of Test No. 2 and Test No. 4 of Example 1. The results are shown in Figures 1 and 2, respectively. The comparative example shown in FIG. 3 is related to Comparative Example 1 in Table 3. Looking at FIGS. 1, 2 and 3, the test according to the present invention
Test No. 2 has almost no change in rapid setting between 0°C and 30°C, but in the comparative example, rapid setting changes significantly between 0°C and 30°C. For .14, the effect of temperature is quite small, although not as much as No. 2, and the proctor penetration resistance value is large overall, confirming the effect of DIPA addition.

[Brief explanation of the drawing]

Figures 1 and 2 show the temperature dependence of rapid setting when polyhydric alcohols are added. The figure shows the results when using the test block of Test No. 14, and Figure 3 shows the temperature dependence of rapid setting when no polyhydric alcohol is added, and the vertical axis shows the proctor penetration resistance ( PSI),
The elapsed time (min) after test block creation is plotted on the horizontal axis. In the figure, 〇...0℃, △...10℃, □...20℃,
◇……30℃.

Claims (1)

[Claims] 1 20-60% by weight of alkali metal aluminate salts,
A quick-setting agent for shotcrete consisting mainly of a mixture of 10-50% by weight of alkali metal carbonate salts and 0.1-10% by weight of polyhydric alcohols.