JPS5997563A - Chemical admixing agent for concrete and manufacture - 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 is a chemical admixture for concrete and a method for producing the same, and its purpose is to improve entrained air performance (AE performance).
Another object of the present invention is to provide a chemical admixture for concrete that has excellent water-reducing performance and is a delayed type water-reducing agent that can retard the setting of concrete.

As is well known, chemical admixtures for I7crete improve the solubility of concrete mainly due to its surfactant action.
-4-1 It is used to completely improve resistance to freeze-thaw effects, etc., and the chemical admixtures for concrete include AE agents, water reducers, and AE water reducers,
In addition, the water reducing agents and AE water reducing agents are classified into standard types, delayed types, and accelerated types, respectively.

The present invention relates to a chemical admixture for concrete as a delayed type AE water reducing agent among the above categories, and a method for producing the same. Conventional AE water reducing agents include astringent sulfonate, creonate oil sulfonic acid formalin condensate, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl allyl ether, and the like.

As a result of many years of research into chemical admixtures for concrete using humic acid as a raw material, the present inventors have developed a chemical admixture for concrete as a delayed-type AE water reducing agent by adopting the structure described in the claims. I was able to get it.

That is, the invention described in claim 1 (hereinafter referred to as the first invention) is a chemical admixture for concrete characterized by comprising a sodium or potassium salt of sulfomethylated nitrofumic acid, The invention still recited in claim 2 (hereinafter referred to as the second invention) is a method for producing nitrofumic acid with a molar ratio of sodium or potassium sulfite to formaldehyde, f:l: 1 to 1:0.3. added with sodium or potassium salt, and
Ratio tl of the total weight of the sulfite and formaldehyde to the nitrofumate: 0.5 to 1:0.
This is a method for producing a chemical admixture for concrete, which is characterized by reacting step 1 to produce a sodium or potassium salt of a sulfomethylated di-I-ro7mic acid.

First, the manufacturing method of the present invention will be described. Nitrohumic acid JML, sulfite, formaldehyde, and water as a medium are collected in a container. Nitrofumate is a water-soluble salt such as sodium or potassium, which has a relatively low molecular weight and is obtained by converting young coal such as lignite, lignite, or peat to nitric acid.

The sulfite is sodium sulfite, potassium sulfite, sodium bisulfite, potassium bisulfite, etc., and each of these may be used alone, or a mixture of two or more of d and a may be used.

A mixture of the nitrofumate and sulfite as described above and formaldehyde is heated to 40 to 100°C to react.

In the above, the molar ratio of sulfite and formaldehyde to be mixed with nitrofumate is 1:1 to 1:0.
．． Mix as 3. The reason for setting the molar ratio of sulfite and formaldehyde to 1=1 to 1:0.3 is that it is 1:1.
This is because formaldehyde forms a co-condensate between molecules of nitrofumic acid or sulfite and becomes insolubilized, making it unsuitable as a chemical admixture for concrete. Furthermore, if the molar ratio is less than 0.3, the amount of hydroxymethanesulfonic acid ions produced is small, and therefore the number of sulfomethyl groups introduced into the nido-07 mate salt is also reduced, which is not preferable.

Further, the ratio of the sulfite and formaldehyde to the weight of the nitrofumate is 1:0.5 to 1:0.1 in terms of the total weight of the sulfite and formaldehyde. In this case, the reason why the weight ratio was limited to the above-mentioned range is that f41- of the sulfomethyl group introduced into dil-roofmic acid is limited.5.
If it is more than 1:0.5, the free sulfomethylated product (hydroxymethanesulfonate ion) will be excessive and will not contribute in any way to the dispersibility or AE performance as a chemical admixture for concrete. This is because less sulfomethyl groups are introduced into the nitrofumate below.

In addition, in the above reaction, the nitrofumate and sulfite to which P was added were heated to 40 to 1000C.)
＼, A predetermined amount of formaldehyde may be gradually added to this to cause a reaction, and this method has the advantage of suppressing condensates formed by methylol between nitrofumates or between nitrofumates and sulfites. .

1. In the above reaction, if the temperature is too high or the reaction time is too long, the condensation reaction with methylol will be accelerated, which is unfavorable. On the other hand, if the temperature is too high or the reaction time is too short, the pressure will be lower than the nitrofuminic acid. Since the sulfomethyl group cannot be sufficiently introduced into the salt, the reaction temperature is preferably 40 to 100°C and the reaction time is preferably 30 minutes to 5 hours.

The product obtained by the method described in detail above consists of salts of sulfomethylated nitrofumic acid such as sulfur, lithium, or potassium, and is water-soluble, and if used as a chemical admixture for concrete, it can be used as a chemical admixture for concrete. It can be completely dissolved in the water mixed in -1 and mixed uniformly into concrete, and due to the synergistic effect of the carboxyl group and sulfomethyl group in nitrofumic acid, as shown in the examples below, ('
AE It can be very effective as a chemical admixture for concrete as a delayed form of water reducing agent.

However, the chemical admixture for concrete of the first invention is
As mentioned above, in principle, by adding a concrete setting accelerator such as sodium chloride, which is a water reducer, the curing time of concrete can be adjusted as desired, and therefore it is used as a standard type or accelerated type of AE water reducer. The advantage is that it can be done.

As described above, the first invention is a chemical admixture for concrete that is made entirely of sulfomethylated nitrofumic acid,
AE It is of course effective as a delayed form of water reducing agent,
By appropriately blending a concrete flocculation accelerator with this, it has the advantage that it can also be used as a chemical admixture for concrete as a standard type or accelerated type of AE water reducing agent.

Moreover, the chemical admixture for concrete according to the present invention has a second
The invention of sulfomethylated nitrofumic acid can be obtained in high yield by simple means, and it will not only promote the development of the use of young coal, but also be of great benefit to the construction industry such as dam construction and building construction. There is something.

Examples Sodium nitrofuminate, 1.1% sodium sulfite, formaldehyde and water were collected and mixed in a reflux-cooled flask under the mixing ratios and reaction conditions shown in Table 1 and reacted. Table 2 shows the results when a concrete test is carried out using 1) and the slump value 'l: 18.
Table 3 shows the results in cm.

First notation ratio and reaction conditions (Note) (1) *I N, F, -Na are sodium nitrofuminate.

(2) *2 Parts by weight are formalin equivalent parts.

Claims (2)

[Claims] (1) A chemical admixture for concrete characterized by comprising a salt of sulfomethylated nitrofumic acid or potassium. (2) Adding the molar ratio of sodium sulfite or potassium salt to formaldehyde to 1:1 to 1:0.3 to the sodium or potassium salt of nitrofuminic acid, and adding the The ratio of sulfite and formaldehyde to the total weight is 1:0.5 to 1:0.
．． 1. A method for producing a chemical admixture for concrete, which comprises reacting step 1 to produce a sodium or potassium salt of sulfomethylated nitrofumic acid.