JPS63236741A - Accelerator for spraying - 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 Field of Application] The present invention relates to a rapid setting agent for spraying mortar or concrete.

[Prior Art] Generally, a spraying method is employed in which a small amount of quick-setting agent is added to cement or concrete material, and this is sprayed onto the walls of tunnels, buildings, etc. to solidify it.

Conventionally, aluminates, alkali carbonates, and calcium aluminates have been used singly or in combination as quick setting agents for spraying.

However, the use of aluminates and alkali carbonates, either alone or in nine combinations, does not have sharp rapid setting properties, which has caused many problems in construction at spring water locations, etc. or,
There was a problem that the range of the optimum amount of quick-setting agent to be added to cement was narrow, making it difficult to manage it at the actual construction site. Furthermore, spraying has the disadvantage that the strength of the mortar and concrete that follows is poor, the strength is particularly low at a young age, and the growth in long-term strength is low. A typical aluminate material is sodium aluminate, but the commonly used materials also have the disadvantage of being highly hygroscopic and having very poor long-term stability.

On the other hand, those containing calcium aluminate as a main component have sharper rapid setting and sufficient strength than the former, but have the disadvantage of requiring a large amount to be added to cement or concrete.

(Problems to be Solved by the Invention) It is an object of the present invention to eliminate the drawbacks of conventional spraying quick-setting agents and to provide an quick-setting agent that satisfies the following conditions.

■ Rapid setting is sharp.

■ Short curing time due to low additive amount.

■ Curing time is shortened in proportion to the amount added.

■High initial strength and long-term strength.

■ Desirably, it is easy to handle and does not change in quality.

[Means for Solving the Problems] The present inventor has made extensive studies to develop a quick-setting agent that satisfies the above conditions, and has developed a method using specific combinations of ultra-fast hardening cement, alumina cement, slaked lime, sodium aluminate, and sodium carbonate. The present invention was completed based on the discovery that a combination of these materials in a specific composition ratio is extremely effective as an quick-setting agent.

The quick-setting agent for spraying according to the present invention is ultra-fast hardening cement 20 to 6
0% by weight, alumina cement 10-40% by weight, alkali carbonate 5-35% by weight, sodium aluminate 5-3%
A spray containing 0% by weight and 1 to 20% by weight of slaked lime is a quick setting agent.

Here, the ultra-fast hardening cements include 3 Ca OS i O2 and Ca
5O and iic a 0 ・7 AD 20 s −
Those containing CaFz as a main compound can be used. This cement is 11Ca0.7 A 1 0 -Ca
Because it develops sufficient strength within a few hours due to the hydration reaction of F 2 and Ca SO 4, it is mainly used for emergency construction.

Alumina cement is also commercially available under this name.
It contains O-A II 20 s as the main compound and has a high curing speed, so it is used for emergency construction.

Common alkali carbonates include sodium carbonate and potassium carbonate.

The slaked lime and alkali carbonate used in the present invention may be those commonly used in industrial applications.

The chemical components of typical commercially available jet cements are shown in Table 1.

Table 1 The chemical components of typical commercially available alumina cements are shown in Table 2.

(The following is a blank space) Table 2 Chemical composition (% by weight) Sodium aluminate is composed of Na 2 O and Al203 as main components, and there are two types: an aqueous solution and a powder. Usually, an Al 2 O/Na 2 O molar ratio of less than 1 is used. However, in the case of a powder, Na2O-rich sodium aluminate has high deliquescent properties, easily absorbs moisture, and lacks long-term stability. Therefore, the sodium aluminate used in the present invention is An 2 o 3 /Na
It is desirable that the molar ratio of 20 to 20 is 1 or more, preferably 1 to 5.

When the molar ratio is 1 or more, the product has very little deliquescence compared to ordinary products, is easy to handle, and has excellent long-term storage stability.

The method for producing sodium aluminate with a molar ratio (AN O/Na 20) of 1 to 5 is described in Japanese Patent Publication No. 58-46450.
JP-A-58-145619, and JP-A-58-140317.

Ultra-fast hardening cement is mainly effective in increasing strength.
Alumina cement is mainly effective in increasing strength and accelerating setting. Sodium carbonate, sodium aluminate,
All slaked lime has the effect of accelerating setting. By mixing these five components at a specific composition ratio, the above conditions ■
An rapid setting agent that achieves all of ~■ in a well-balanced manner can be obtained. For ultra-fast hardening cement and alumina cement, fineness (Blane value) is usually 4000 to 6000 crI/
Although it is commercially available in gram size, it is an ultra-fine powder (powder size 65).
00 cm2/g or more) is preferred in terms of increasing the reactivity of the quick setting agent and further shortening the setting time. In order to produce ultrafine powder from commercially available products, dry pulverization may be performed using a commonly used pulverizer such as a vibration mill, a ball mill, or a jet mill type pulverizer. Regarding the degree of pulverization, it is preferable to make the particle size finer because the rapid setting performance improves, but in order to achieve the object of the present invention, it is sufficient that the degree of pulverization is 6500 cm2/g or more.

[Examples and Comparative Examples] In order to clarify the effects of the present invention, Examples and Comparative Examples will be described below, but the technical scope of the present invention is not limited to these Examples.

The tests included (1) a setting test and (2) a strength test.

(1) Setting test and (2) Strength test using a mortar mixer, using 1500 g of fine aggregate (FM2.7 from Kashima).
90 g of primary water was added to the mixture and dry kneaded for 1 minute to bring the water content to 6%.

Next, 500 g of cement and a predetermined amount of quick-setting agent were put into a mixer and mixed for 30 seconds, then 160 g of secondary water was added and kneaded for 15 seconds, and this was immediately packed into a form and subjected to a broctor penetration resistance test. (ASTM-C-403) and strength test (JIS R5201) were conducted.

The test was conducted in a room with a temperature of 20±3° C. and a humidity of 80% or higher, and the specimens were cured in water at a temperature of 20±3° C. after the first day of age. Broctor penetration resistance test (condensation test)
The end time was set at Broctor Penetration Value (PSI) of 4000 PSI.

(1) Setting test The amount of quick setting agent added and the completion time of the product of the present invention (Example), a comparative product with a different composition of five components, and a commercially available product (commercially available as a spraying agent) (Comparative Example). I investigated the relationship. The materials used were ultra-fast hardening cement and alumina cement, which were ordinary commercially available products, and these commercially available products were crushed to a powder degree of 8,500 cm2.
/ g or more ultrafine powder and both were used.

Slaked lime, potassium carbonate, and sodium carbonate were commercially available materials with a purity of 99.5% by weight or higher. Regarding sodium aluminate, the particle size is 1 mm or less, and the molar ratio is 1 or more (chemical composition AR20373, 7% by weight, Na
A (molar ratio of !20s/Na20 of 1.8) was used at 5.0% by weight of O2.

Also, commercially available products are quick-setting materials containing sodium aluminate as a main component.

Table 1 shows the completion time for each composition of quick setting agent.

Samples A to G used commercially available ultra-fast hardening cement and alumina cement as raw materials, and A1°B, C, and C used commercially available cement pulverized to a fineness of 8,500 ctl/g or more.

From Table 3, it can be seen that the products using the quick-setting agent of the present invention had a shorter setting completion time than those of the comparative example.

(Left below) Next, the relationship between the amount (wt%) of the quick setting agent added to the cement and the completion time of setting was measured. Table 4 shows the measurement results for At (Example) and commercial products (Comparative Example). In the Examples, the completion time decreases as the amount added increases, but in the Comparative Examples, the completion time does not shorten even if the amount added increases.

Table 4: Regarding sodium aluminate, Al2O3/N
A commercial product with a molar ratio of a2O of 1 or less (molar ratio of 0.85) was also tested, but the completion time was different from that in Examples A and A.
,B,B,C.

There was no significant difference between C and C.

(2) Strength test It goes without saying that the higher the strength, the better the quick setting agent. However, mortar or concrete to which an accelerating agent is added generally has better initial strength than mortar or concrete without an accelerating agent, but long-term strength is significantly lower.

Using Example (A1) and Comparative Example (commercial product), the compressive strength was measured by increasing or decreasing the amount of quick-setting agent added at 3 hours and 1 hour.
It was carried out on 280 days on the 7th and 7th.

The results are shown in Table 5.

(Leaving space below) Table 5 Comparing the Examples and Comparative Examples, the Examples are superior in strength at young age (3 hours) and at long age (28 days).

Further, as the amount of the quick-setting agent added increases, the strength of the commercially available product decreases, but the strength of the examples does not decrease.

Regarding sodium aluminate, samples with a molar ratio of Al2O3/Na2O of 1 or less were also measured, but there was no significant difference in strength from those with a molar ratio of 1 or more.

Comparisons were made regarding ease of handling and long-term stability of sodium aluminate with a molar ratio of Al2O3/Na2O of 1 or more (improved product) and a normal commercially available product. The chemical composition is AN 203 as a molar ratio of 1 or more.
73.7% by weight, Na 025.0% by weight, and A
X) A product with a molar ratio of 203 /Na2O of 168 was used, and the chemical composition was AI 20353.0 as a commercial product.
wt%, Na038.0 wt%, Al2O3/N
The one with a molar ratio of a2O of 0.85 was used.

Commercially available products have very high deliquescent properties, and if left indoors for one day, they absorb moisture from the air and become sticky, making them difficult to handle. However, those having a molar ratio of 1 or more had almost no deliquescent property and had no problem in handling. In addition, when pulverizing with a mortar or various types of pulverizers, there was a clear difference. Those with a molar ratio of 1 or more had good pulverization properties, but the commercially available products became sticky after being pulverized.

From these results, it can be said that those with a molar ratio of 1 or more are easier to handle than those with a molar ratio of less than 1, and the quality is stable over a long period of time.

[Effects of the Invention] The quick-setting agent for spraying according to the present invention has sharp quick-setting properties, has a short curing time when added in a low amount, and has a short curing time in proportion to the added amount, so it is suitable for on-site construction. Easy to manage.

It also exhibits strength that poses no problem in practical use. Furthermore, as sodium aluminate, Al2O3/Na20 is 1~
If No. 5 is used, it is easy to handle and the material is hard to change in quality, so it has excellent long-term stability.

Claims (1)

[Claims] 1. 20-60% by weight of ultra-fast hardening cement, 10-40% by weight of alumina cement, 5-35% by weight of alkali carbonate,
Sodium aluminate 5-30% by weight, slaked lime 1-20%
Quick setting agent for spraying consisting of % by weight. 2. Sodium aluminate Al_2O_3/Na_2
The rapid setting agent for spraying according to claim 1, characterized in that the molar ratio of O is 1 to 5. 3. Ultra-fast hardening cement has a fineness (Blaine value) of 6500c
The quick-setting agent for spraying according to claim 1, which is an ultrafine powder of m^2/g or more. 4. Fineness of alumina cement (Blaine value) 6500
The rapid setting agent for spraying according to claim 1, which is an ultrafine powder of cm^2/g or more.