JPS5815054A - Manufacture of high strength 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 provides a method for producing high-strength concrete, and more specifically, a method for producing high-strength concrete, and more specifically, a method for reducing the slump of fresh concrete that has not yet hardened, while reducing the delay in setting and the decrease in initial strength to a level that does not cause any practical problems. This invention relates to a method for producing high-strength concrete that reduces deterioration over time.

Today, when manufacturing high-strength concrete products such as high-strength piles, balls, bridge girders, and humid pipes, water reducers are used to reduce the unit water volume of richly mixed concrete containing a large amount of cement to obtain high strength. In particular, β-naphthalene sulfonic acid formalin high condensate salt (hereinafter abbreviated as NSF) is frequently used as a water reducing agent.

By the way, in general, in the case of ordinary concrete with a cement amount of less than 400 kp/m', for example, a cement amount of 250 to 400 kp/nl, a decrease in the slump of the concrete due to changes over time is not considered to be such a big problem in practice. However, the disadvantage of concrete with a rich mixture containing a large amount of cement and a highly water-reduced state (hereinafter referred to as high-strength ready-mixed concrete) is that its slump decreases significantly over time. It has been pointed out that work will be hindered if the reeds are not poured in a short time, and improvements in this respect are strongly desired.

However, when used alone, NSF, which is widely used today, exhibits an excellent water-reducing effect and is recognized as an extremely effective water-reducing agent for developing the strength of concrete products, but its biggest drawback is is that the slump of high-strength ready-mixed concrete decreases significantly over time.

Therefore, attempts have been made to investigate various additives and additives to be used in combination with NSF in order to improve such drawbacks of NSF, but at present none of them is satisfactory in preventing the above-mentioned slump from changing over time.

For example, when salts of oxycarboxylic acids such as gluconic acid and glucoheptonic acid (hereinafter referred to as GS salts) are used together, the effect of preventing the slump of high-strength fresh concrete from changing over time is weak, and the setting retardation is large, so When steam curing is performed to shorten production time, as in the case of high-strength concrete products, strength development is significantly inhibited. Also,
When cement admixtures such as lignin sulfonate or nonionic surfactants are used in conjunction with NSF, they have little effect on preventing slump from changing over time, resulting in a reduction in compressive strength and making it impossible to obtain the desired concrete strength. .

In view of this situation, the present inventors have developed a water reduction method that can significantly reduce the change in slump over time in the production of high-strength concrete products, and also prevent the delay in setting and the decrease in initial strength to an extent that does not cause any practical problems. As a result of intensive research on the agent, we found that it contains 97 to 80 parts by weight of N5F and an ethylene oxide adduct of gluconate (hereinafter abbreviated as GS EOn, where n is the number of moles added), with a content of 1 to 1 ethylene oxide per mole of gluconic acid. It was discovered that a mixture containing 3 to 20 parts by weight of the product obtained by adding 5 moles of water is an extremely excellent water reducing agent, and the present invention was completed. That is, in order to improve the above-mentioned conventional drawbacks, the present invention aims to improve the production of high-strength concrete products while reducing the setting delay and the decrease in initial strength to an extent that does not cause any practical problems. This provides a manufacturing method with less slump change over time, and this is N5F
97 to 80 parts by weight and GS-EOn (where n is 1 to 5)3
This can be achieved by adding a mixture containing up to 20 parts by weight as a water reducing agent to high-strength fresh concrete IJ-2.

Additionally, when GS-EOn is used alone as a water reducing agent for high-strength ready-mixed concrete, setting is substantially delayed at the level of addition that provides the desired water-reducing effect (final strength). , there is a problem in the initial strength development, but the present invention does not solve the problem of GS
The surprising fact that the above-mentioned present invention was achieved through detailed research on the mixing ratio of EOF2 and NSF having the drawbacks described above, the number of moles of ethylene oxide added to GS EOF+, the amount added to cement, etc. It is based on the discovery of

The NSF used in the present invention is Patent Publication No. 117 of 1962.
The compound described in No. 37 is a reaction product obtained by subjecting β-naphthalene sulfonic acid to a highly formalin condensation reaction until the remaining amount of unreacted sulfonic acid becomes 8% or less.
GS-EOn, which is also used in the present invention, is a compound described in Patent Publication No. 18672 of 1982, and is a product obtained by adding a predetermined number of moles of ethylene oxide to an aqueous gluconate solution using an alkali catalyst.

In the water reducing agent containing NSF and GS EOn used in the present invention, the content ratio of NSF and GS EOn is in the range of 97 to 80/3 to 20 (weight ratio). G
If the ratio of S EOn is less than 3, there is no effect in reducing the aging change in slump of high-strength ready-mixed concrete, and conversely, if the ratio is more than 20, setting retardation becomes large and steam curing is not effective. inhibits initial strength development in Even more preferably, the content ratio is 90-85/10-1
5 (weight ratio). In addition, the number of moles of ethylene oxide (hereinafter abbreviated as EO) added to GS and EOn is 1 to 5.
In general, the larger the number of moles of EO added, the greater the effect of preventing slump reduction and the smaller the setting retardation, so the development of initial strength tends to be relatively quick.
If the number of moles added exceeds 5 moles, the water-reducing effect decreases, which is not preferable. Furthermore, in the present invention, the amount of water reducing agent used relative to cement is 0.3 to 0.8 parts by weight, but
．． If it is less than 3 parts by weight, the water reduction effect will be poor, and if it is more than 0.8 parts by weight, it will delay the setting of high-strength ready-mixed concrete and inhibit the development of initial strength during steam curing.
A cement water reducer having a content ratio of NSF and GSEOF+ (where n is 1 to 5) in the range of 97 to 80/3 to 20 (weight ratio) is added to high-strength ready-mixed concrete by 0.3.
By adding in the range of ~0.8% (weight ratio to cement), the above-mentioned high-strength ready-mixed concrete has (1) high water-reducing properties, (2) prevention of slump deterioration over time, and (3) practical use. It reduces setting retardation to a level that does not cause any problems and develops early strength. It can simultaneously provide the above three properties that were not found in conventional high-strength ready-mixed concrete. In particular, the amount of cement is 400 kg/
- It is more effective when the mixture is richer than above.

Hereinafter, the structure of the present invention will be explained in more detail with reference to Examples and Comparative Examples. However, the present invention is limited to these Examples and Comparative Examples. The water reducing agent in the Example and the water reducing agent in the Comparative Example were adjusted, and a concrete test was conducted using the formulations of Experiment 1 and Experiment 2. Tables 1 and 2 are the measurement results of Experiment 1, and Tables 3 and 4 are the measurement results of Experiment 2. In the table, the number appended to GS indicates the number of moles of EO added. Graphs in which these measurement results are organized and plotted are shown in FIGS. 1 to 6. In the figure, the numbers appended to each plot point indicate Nα in the table above.The materials used are listed in the following 1).
The test method is the same as described in section 2) below.

1) Material used: Cement: Ordinary Portland cement manufactured by Sumitomo Corporation
Specific gravity = 8.16 Fine aggregate: Oi river sand Specific gravity = 2.63 Coarse particle ratio -2,
80 Coarse aggregate: Crushed stone from Hachiyama Specific gravity = 2.66 Coarse particle ratio = 6.
66 Water: Gamagori City Water 2) Test method Concrete mixing: JIS-A1138 slump
:JIS-AIIOI air volume :JI
S-A1128 compressive strength: JIS-A113
2 and 1108 Condensation Test: ASTM-C403 Steam Curing Conditions.

Pre-curing: 20℃, 3 hours temperature curing 20℃/hour Isothermal curing: 65℃, 3 hours Change in slump: Concrete after mixing) 2()1
0 Experiment 1 Amount of water reducing agent used (relative to cement): 0.5% (weight) Unit amount of cement: 4 s o kg/m' Fine aggregate ratio = 40% Table 1 Experiment 2 Unit cement amount: 450 kg/m' Fine aggregate ratio: 40% Table 3 Summarizing these measurement results, the following is clearly known. .

From Figure 1, when the content of NSF in a water reducing agent consisting of NSF and GS EOF+ is in the range of 97 to 80% (by weight), the slump retention rate of the concrete after 30 minutes (hereinafter abbreviated as slump retention rate) ) is clearly superior to NSF alone. Good results were also shown when the NSF content was 70%, but in this case, the second
As is clear from the figure, the initial strength decreases.

From FIG. 2, under the same conditions as in FIG. 1, the water reducing agent of the present invention has no practical difference compared to NSF alone.
It has an initial compressive strength (hereinafter referred to as initial strength) after one day of steam curing, but if the NSF content is less than 80%, the initial strength decreases. Also, GS EO
When the n content is less than 3% or when 3% GS salt is used instead of GS EOn, the initial strength is good but the first
As is clear from the figure, the slump retention rate decreases.

From FIG. 3, it is clear that when the number of moles of GS EOn added is varied, a range of 1 to 5 moles exhibits a good slump retention rate. On the other hand, in the case of GS salt, the slump retention rate decreases.From Figure 4, GS EOn
It is clear that good initial strength is exhibited when the number of moles added is 1 to 5.
It is clear that when added, the slump retention rate is good. When the content of GS-E'On is small, the slump retention rate is good even when the amount added is 0.2%, but as is clear from FIG. 6, the initial strength is lowered.

As explained above, in the present invention, the content ratio of NSF and GS EO* (where n is 1 to 5) is 97 to 80/3 to 20 (weight ratio) in high strength fresh concrete. A cement water reducer with a composition ranging from 0.3 to 0,
By adding 8% (based on the weight of cement), it imparts a high level of water-reducing properties to the high-strength ready-mixed concrete, prevents the decline in slump due to changes over time, and retards setting to a level that does not cause any practical problems. It has the effect of reducing the initial strength and allowing the initial strength to develop.

[Brief explanation of drawings]

Each figure is a graph showing the properties of high-strength ready-mixed concrete in the present invention on the vertical axis, and Figure 1 shows the NSF content (%) in the water reducing agent used in the present invention after 30 minutes. Figure 2 is a graph displaying the slump retention rate (%, with the immediately after being taken as 100%), and Figure 2 shows the same NSF content (%) as Figure 1.
%) versus the compressive strength after one day of steam curing (Iw/
d), Figure 3 is a graph showing the same slump retention rate as Figure 1 against the n number of GS EOn in the water reducing agent used in the present invention, and Figure 4 is a graph showing the same slump retention rate as in Figure 1. A graph showing the same compressive strength as in Fig. 2 for the n number similar to Fig. 3, and Fig. 5 is a graph showing the compressive strength similar to Fig. 1 for the amount (%) added to cement of the water reducing agent used in the present invention. FIG. 6 is a graph showing the same slump retention rate, and FIG. 6 is a graph showing the same compressive strength as in FIG. 2 for the same addition amount as in FIG. 5. Patent Applicant: Takemoto Oil & Fat Co., Ltd. Agent, Patent Attorney: Hiroshi Iriyama

Claims (1)

[Claims] 1. 97 to 80 parts by weight of a salt of formalin high condensate of β-naphthalene sulfonic acid and an ethylene oxide adduct of gluconate, in which 1 to 5 moles of ethylene oxide are added to 1 mole of gluconic acid. Add a water reducing agent for concrete containing 3 to 20 parts by weight of 0.3 to 20 parts by weight to cement.
A method for producing high-strength concrete using 0.8 parts by weight added. 2. The method for producing high-strength concrete according to claim 1, wherein the amount of cement is a rich mix of 400 kf/- or more.