JPS59174555A - Manufacture of ae fly ash 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 The present invention relates to a method for producing concrete containing fly ash with a stable entrained air ratio.

AE fly ash concrete reduces the unit water volume of concrete due to the so-called sol bearing effect of fly assemblies, the combination of the silicic acid content of fly ash and cement, and the effect of fine entrained air due to the addition of AE agents. It is already known that it has many advantages, such as improved workability, increased long-term strength, improved watertightness, improved durability, especially freeze-thaw resistance, and reduced hydration calorific value.

However, fly ash contains ash from coal-burning boilers such as power plants, and unburned carden remains. The water absorbs the AE agent, reducing the effectiveness of the AE agent. The amount of unburned cargin remaining varies depending on the type of coal used and the collection conditions. Therefore, the amount of air entrained in AI concrete containing fly ash varies greatly, and the amount of air cannot be controlled within a specific preferred range. It is extremely difficult to manage this within the limits.

Normally, when fly ash is blended to produce AE concrete, it is difficult to obtain the desired amount of air in the concrete even if a standard amount of a commercially available AE agent is used. Therefore, in order to obtain the desired amount of air, a certain amount must be used,
The amount of unburned carbon remaining in fly ash varies depending on the operating conditions under which the fly ash is produced.
If the amount of carbon is large, there will be less entrained air, resulting in concrete that cannot be expected to have durability such as freeze-thaw resistance1.
Also, if the amount of carbon is small, there will be a lot of air entrained, which will reduce the strength of the concrete, which will not be satisfactory in terms of strength. be.

Therefore, as a method to keep the air amount within a certain range, it is necessary to understand the quality fluctuations of fly ash, that is, the amount of unburned carbon, in advance by conducting a methylene blue adsorption amount test, etc.
A method of determining the amount of air added is considered, but the work is very complicated and there is a time lag, so as a practical matter, it is difficult to continuously and stably manufacture comfried troughs containing the desired amount of air. It is possible.

In addition, although concrete mixed with ordinary AE agents contains the desired amount of air immediately after manufacture or when unloading at the site of use, it is not only the end-wrapped air that is introduced during the transportation, pouring, and compaction processes. A significant portion of the fine entrained air introduced by the AE agent is dissipated, reducing the amount of air and resulting in a concrete structure with less air than is required for freeze-thaw resistance in terms of concrete engineering. In AE concrete containing fly ash, the tendency for entrained air to be lost in the post-manufacturing process is more pronounced.

Therefore, from the point of view of effective utilization of resources, production of concrete of stable quality, and obtaining of concrete structures with desired performance, the amount of entrained air is not influenced by the amount of unburned and carbon residue in fly ash. Stable bubble A
The emergence of agent E is strongly desired.

In order to solve these problems, the present inventors have conducted intensive research on a method for manufacturing AE fly ash concrete that can maintain a stable amount of entrained air regardless of the amount of unburned carbon, and have found, for example, It was discovered that a reaction product obtained by reacting a specific number of moles of ethylene oxide with a seed sorbitol, or a product obtained by esterifying the terminal of the 4-lyoxyethylene group of the reaction product with a certain fatty acid, exhibits excellent effects. , completed the invention.

The present invention provides a method for producing concrete using cement as a binder, in which the general formula CHO(CH2CH20)&Z (where X, Y
means repeating the chain in the direction of the hydrogen source, 13a+
b+c≦85°2 is a method for producing AE fly-assembly concrete characterized by using an AE agent containing as an active ingredient a compound represented by a hydrogen atom or a fatty acid residue having 16 to 22 carbon atoms.

The AE agent used in this Akanemei is, for example, one obtained by adding 12 to 85 moles of ethylene oxide to sorbyl, or one obtained by reacting it with 1 to 3 moles of a fatty acid having a carbon content of 16 to 22. It is. To explain the AE agent in more detail, for example, 1 mol of nrubitol was charged into an autoclave, the temperature was heated to 120°C after replacing with N2, and then
12-85 moles of ethylene oxide at 120-18o'C,1
It is added at ~5ky/1yn2. One mole of this product contains a fatty acid having 16 to 22 carbon atoms, such as iso-lumitic acid.

1 to 3 moles of isostearic acid, oleic acid, etc. are charged to double the ester ratio, and after adding 0.5% by weight of potassium carbonate to the fatty acid, an esterification reaction is carried out at 210 to 230°C to obtain a compound according to the present invention. get. This compound is
It has a nonionic surfactant effect and is the main component of the AE agent of the present invention.

The fatty acid ester of polyoxyethylene sorbitol, which is the main component of the AE agent of the present invention, has 12 to 85 oxyethylene groups in one molecule because sorbitol contains a polyhydric alcohol residue with 60 carbon atoms and an adjacent hydroxyl group. Water-soluble ones with molar addition are used. If the oxyethylene group in the molecule is less than 12 moles, the water solubility is low and the AE effect, that is, the introduction of air bubbles into the concrete during concrete production is poor, so it is not preferable. On the other hand, if the amount exceeds 85 moles, although it is water-soluble, the surfactant ability decreases, so it is not preferable as an AE agent.

In the present invention, the AE agent may be blended by adding and mixing the nucleating agent to fly ash or fly ash cement mixed with fly ash in advance, or by a method similar to the method of using known AE agents. However, the order in which each material is added to the concrete manufacturing process does not matter.

The required amount of the AE agent according to the present invention is almost not affected by the blending ratio of fly ash or the amount of unburned carden in the fly ash, but preferably the amount of air introduced is 3 for the content of fly ash and cement. Depending on the amount of air, such as 0.03 to 0.09%, it is preferably determined by trial kneading, which is a common method.

In the method of the present invention, fly ash refers to ash remaining after coal combustion, such as fly ash, green ash, or pulverized ash collected in a dust collector of a pulverized coal-fired boiler in a power plant. In addition, any known so-called cement may be used as the cement.
For example, normal, early strength, super early strength, moderate heat, and Portland cement.

These include jet cement, blast furnace cement, silica cement, and alumina cement.

In carrying out the method of the present invention, various admixtures conventionally used to improve the properties and performance of concrete, such as cement dispersants, concrete water reducers, hardening accelerators, etc., may be used as long as they do not impair the purpose of the present invention. Can be used in combination with curing retarders, waterproofing agents, rust preventives, shrinkage reducing agents, expansion agents, etc.

According to the present invention, since the amount of air entrained is not affected by the amount of unburned carbon remaining in the fly assembly, concrete containing the desired amount of air can be obtained.
i = It has become possible to produce continuously and stably. In addition, during the process of transporting the manufactured ready-mixed concrete to the site of use, is there a phenomenon in which the entrained air decreases or the ready-mixed concrete hardens (commonly known as air-drog or slang-drog), which is noticeable in conventional AE concrete? Moreover, it is much less compared to conventional commercially available AE agents.

Furthermore, the amount of air decreases little during the concrete pouring and compaction steps after unloading, and the concrete water reducing agent also has a significantly large number of fine air pores remaining. It is generally said that if the amount of air increases by 1%, the compressive strength decreases by 5 inches, but even though a large amount of air remains in the cured product, the manner in which the strength is developed is different from that of conventional commercially available AE.
It is at least the same level as the one containing the agent.

In addition, the method of the present invention is less affected by the amount of residual unburned carbon in the fly ash blended than the method previously filed by the applicant (Japanese Patent Application No. 148713/1982). Furthermore, the air bubbles introduced during the concrete manufacturing process are smaller, more stable, a larger proportion of the air bubbles are finally fixed in the hardened concrete, and the effect is that the strength is greater.

In addition, according to the present invention, it is difficult to produce concrete with a stable amount of entrained air because conventional concrete using fly ash is affected by unburned carbon contained in fly ash and fluctuations in its amount. Although it was thought to be impossible, it has now become possible to produce concrete with a stable amount of air at all times without being affected by the presence of unburned carbine. Therefore, it can be said that the present invention opens the door to even more effective utilization of fly ash, an underutilized resource.

Furthermore, according to the present invention, the ratio of the amount of air bubbles contained in the concrete at the time of manufacture or unloading is stable, and the rate of disappearance of the air bubbles in the subsequent process is extremely small compared to conventional ones. Therefore, it has finally become possible to create concrete structures with excellent durability, especially structures with excellent freeze-thaw resistance and a longer service life.

Next, the structure and effects of the present invention will be explained in more detail with reference to Examples and Comparative Examples.

As shown in Table 1, the fly ash used was of three types with different adsorption amounts of methylene blue and different amounts of unburned carzene remaining.

Table 1 Synthesis examples of the AE agents used are shown below.
mol is added at 120-180°C with a value of 1-5 and 27,
Ta. Next, 1 mole of this sorbitol 40EO adduct was charged into an ester can, and 2 moles of oleic acid was charged therein.
Then, after adding 0.5% potassium carbonate to oleic acid, an esterification reaction was carried out at 210 to 230°C to obtain a compound (2).

AE-■: In the above AE-■, 25% of ethylene oxide
Synthesis was carried out in the same manner except that 1 mole of oleic acid was added and 1 mole of oleic acid was reacted to obtain a compound (2).

AE-■; In the above AE-■, 60% of ethylene oxide
Synthesis was carried out in the same manner except that molar addition was carried out and 3 moles of oleic acid was reacted to obtain a compound (2).

AE-■, AE-■, AE-■; Each of the above AE-■
Synthesis was carried out in the same manner as AE-■ and AE-■ except that isostearic acid was used instead of oleic acid as the fatty acid to obtain Compound 1, Compound 2, and Compound 2, respectively.

The admixture materials used are shown in Table 2.

Table 2 As a reference example, the AE agent according to the invention previously filed by the applicant (Japanese Patent Application No. 148713/1982) was used in place of the AE agent of the present invention. This product was obtained by reacting 1 mole of oleic acid with 1 mole of sorbitol and adding 28 moles of ethylene oxide to the product.
In polyoxyethylene sorbitan monooleate having the following structural formula, the molar ratio of ethylene oxide groups and oleic acid residues within the same quadruplets is kept within a certain range. The cement used was ordinary Portland cement or fly ashy cement obtained by mixing this cement with fly ash FA-■, ■, or ■.

The fine aggregate and coarse aggregate used are shown in Table 3.

Table 3: The mix of concrete is shown in terms of the amount of material used for p 1 m3 of concrete. The abbreviations used at that time indicate the following materials. That is, W: water, C: cement, FA: fly ash, S: fine aggregate (sand),
G: coarse aggregate, W/C: water-cement ratio.

s/a: fine aggregate ratio (S/a+G, absolute volume ratio) To manufacture concrete, a predetermined amount of each material is put into a 40-ton capacity forced stirring mixer, and after all materials are added, the concrete is heated for 3 minutes. I used the mixing method.

The concrete test is performed on concrete that has not hardened yet)K
Accordingly, the slump measurement was carried out in accordance with JISA IIOI, and the air amount measurement was carried out in accordance with JIS A1128. In addition, the compressive strength test for hardened concrete is conducted by JIS A.
1108, and the cell spacing coefficient was determined using the modified point counting method of ASTM C457.

Examples 1-3. Comparative Examples 1-3. Reference Examples 1 to 3 Fly ash FA-■, FA-■ or FA-■60ki9° Cement C240kg, fine aggregate S, coarse aggregate G-■.

Using the AE agent AE■ and water, mix at a water-cement ratio of 55%, set the target air volume of the concrete to 4.5 inches, the target slump to 18α, and determine the composition shown in Table 9-4 by trial mixing. Ta.

Table 4 AE fly ash concrete was manufactured using this formulation, and the resulting concrete was tested for air content, slump, and compressive strength at 7 days and 28 days.

For comparison, concrete was manufactured and tested in the same manner as in the example using Vinsol as an AE agent and the one of the previous application as an AE agent for reference. The results of those tests are summarized. It is shown in Table-5.

Fruit/male side 4-9. Comparative Examples 4 to 5 Commercially available Class B fly ash, cement, and AE agent were mixed with 1 mole of sorbitol and 12,1 mol of ethylene oxide (E.0.).
adding 8, 25, 45, 65 and 85 moles;
Concrete was produced and tested under the same conditions as in Example 1, using 180 Il of each material obtained by esterification with 1 mole of oleic acid.

As comparative examples, 8 moles and 95 moles of ethylene oxide were also produced and tested in the same manner.

The results of those tests are summarized in Table 6.

Examples 10-15. Comparative Example 6 Water cement ratio 50%, target air amount 5% and slump 20
In order to produce CRN's lightweight AE fly ash concrete, 380 kg of fly ash cement prepared to contain 20 g of fly ash F'A-■, fine aggregate S, G-■ as coarse aggregate, water and AE agent. Using AE-■ to ■ as synthesis examples, the table-
The formulation shown in 7 was determined. According to this formulation, the AE agent was added to the mixing water in advance to produce concrete.
The air content and slump were measured after minutes and 60 minutes, and the compressive strength was tested at 7 days, 28 days, and 91 days.

For comparison, Gainsol was used as an AE agent in an amount equivalent to 2.6 times that of AEs (1) to (2) in Examples. 6
4:l and similar tests were conducted.

The results of those tests are summarized in Table 8.

Implementation example 16. Comparative example 7. Reference example 4 Fly ash FA-■ 27YU and ordinary cement 273kIi1 as cement, S-■ as fine aggregate, 1:1 mixture of G-■ and G-■ as coarse aggregate, water reducer Hozolith A 5 LN as admixture A Using E agent AE-■, water-cement ratio 52%, target air amount 4.5 inches, slan f16
The formulation shown in Table 9 was determined by trial kneading to obtain 1 m3 of fresh concrete of ctn.

Example 10 Regarding concrete manufactured with this mixture
The same air volume, slump, and compressive strength tests were conducted, and the cell spacing coefficient was also measured.

In addition, using the AE agent Pozolith 303A as a comparative example,
As a reference example, the AE agent used in the applicant's prior invention was similarly produced and tested.

The results of those tests are summarized in Table 10.

Claims (1)

[Claims] (1) In a method for producing concrete using fly ash and cement as binders, general elementary atoms or (CHO.(CH2CH20)b-2)4. Tatashi,
()CH20 (CH2CH20).・z means repeating the chain in the vertical direction, 12≦a +
b + c≦85. z is a hydrogen atom or carbon number 16-2
A method for producing AE fly ash concrete, characterized by using an AE agent containing a compound represented by (fatty acid residue (2)) as an active ingredient.
09. The manufacturing method according to claim (1), wherein