JPS5855357A - Concrete retarder - 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 object of the present invention is to provide a concrete setting retarder which is excellent in the effect of retarding the setting of concrete, has no pseudo-setting properties, and does not cause a decrease in compressive 9 bending strength. .

Concrete setting retarder (hereinafter referred to as setting retarder) is
It is used to prevent workability from decreasing during hot concrete construction, prolonging the transportation time of Ready Mist concrete, and preventing coal P joints from occurring in large structures.

With conventional setting retarders, if the amount added is increased, setting will be delayed accordingly, but because the amount of entrained air becomes excessive, the compressive bending strength may be weakened, and pseudo-setting (i.e. It has the disadvantage of causing rapid viscosity), which adversely affects workability.

Furthermore, as such a setting retarder, natural humic acid has been known for a long time to have a setting retarding effect, and is actually used as a setting retarder. However, when humic acid is used as a setting retarder, there is a drawback that the setting delay time does not increase in proportion to the amount added, and pseudo-setting occurs, which is common when organic substances are added.

By using humic acid as a setting retarder, the present invention exhibits a setting retarding effect proportional to the amount added, and also has no pseudo-setting property. I was able to obtain the drug.

Humic acid has a molecular weight of 10 to 2×10
5 or 3 x 105, and the setting retarding effect of humic acid is due to the fact that active groups such as carboxyl groups, phenolic hydroxyl groups, and alcoholic hydroxyl groups in humic acid are mainly hydroxylated in cement. It is thought that it reacts with lime to produce poorly soluble calcium humate, which is deposited on cement particles and suppresses the hydration of cement.

In the present invention, amino acids having a molecular weight of 10 to 105 are extracted from the above-mentioned amino acids and made into water-soluble salts. Here, water-soluble salts include sodium, potassium, ammonium, etc.
species or two or more species.

Those having a molecular weight of 103 to 105 can be easily fractionated and extracted by ultrafiltration.

Next, the present invention will be explained in detail using the following various experimental examples.

Experimental Example 1 Regenerated humic acid having a molecular weight of 10 to 3 x 105 obtained by nitrating lignite was dispersed in an IJium solution.

After stirring to dissolve soluble components, insoluble components were removed by filtration.

Next, low molecular weight parts were removed using an ultrap filter membrane with a molecular weight cut off of 10 to obtain product A of the present invention.Separately, the regenerated humic acid was dispersed in a sodium hydroxide solution, and the soluble content was stirred.・After dissolution, undissolved matter was separated by sedimentation.

Next, the clarified liquid was passed through an ultrap filter membrane with a molecular weight cutoff of 105 to remove high molecular weight portions, and further the low molecular weight portions were removed using an ultrafiltration membrane with a molecular weight cutoff of 103 to obtain product B of the present invention. The fractionation results are shown in Table 1. In Table 1, "Regenerated sodium 7 mate ω)" indicates that the molecular weight fractionation is not performed (
same as below).

Experimental Example 2 A cement paste test was conducted using Experimental Example 10A.

That is, ordinary Portland cement manufactured by Sumitomo Corporation is made into a cement paste according to JISR-5201, and the amount of setting retarder added is 0.25% of the weight of the cement.

The results are shown in Table 2.

As is clear from the results in Table 2, it is recognized that the setting retardation effect is particularly excellent with molecular weights in the range of 5 x 10' to 103, but with molecular weights in the range of 105 to 5 x 10
'' also has a better setting retardation effect than plain and those with a molecular weight of 105 or more, and therefore those with a molecular weight in the range of 10 to 10 can be used practically. Note that unfractionated regenerated sodium humate is comparable in coagulation time to that with a molecular weight of 105 to 5 x 10', but it is unfavorable as it produces heavy viscosity.

Experimental Example 5 Regenerated sodium humate ('I') of Experimental Example 1 and products A and B of the present invention were added at 0.25% to cement mortar (these are respectively referred to as T1 * Ale B1) and 0.50%. % added (each of these is T
2. A2. B2) was tested. The results are shown in Tables 3 and 4.

As is clear from the results in Table 3, the invention products A and -A2
w Bj ' It is recognized that the initial time of coagulation of B2 can be significantly delayed compared to plain, and unlike T1 m T2 of regenerated sodium humate that is not fractionated, the amount of the product of the present invention added is doubled. By doing so, the initial setting time can be further delayed by about 3 hours.

Furthermore, according to the strength test in Table 4, by adding the product of the present invention,
There is almost no effect on the strength, especially for products A2 and B of the present invention.
It is recognized that even when 0.5% of each is added as in No. 2, there is almost no effect on the strength.

Experimental Example 4 Inventive product similar to Experimental Example 2 A1 m A2 s B1
*B2. T4. Regarding T2, tests were conducted on concrete using the mixing ratios shown in Table 5. The results are shown in Tables 6 and 7.

Table 7 Concrete strength test results (kg/crd)
Type of retarder After 3 days After 7 days 2g
Note: Concrete strength is tested according to JI8A-1108.

As is clear from Table 6, the products of the present invention include not only plain but also recycled sodium amate T.

A clear setting time delay effect was observed compared to T2,
It is also observed that the setting time of the products A2 and B2 of the present invention can be significantly increased as the amount added increases.

Furthermore, from Table 7, it is recognized that even when the amount of the product of the present invention added is increased, there is almost no effect on concrete strength.

In addition, in each of the above experimental examples, recycled humic acid was used as the raw material and sodium salt was used as the water-soluble salt.
Such experimental results were obtained even when natural humic acids were used as raw materials, when potassium salts or ammonium salts of the various humic acids mentioned above were used, or when two or more of humic acids such as sodium salts, potassium salts, ammonium salts, etc. were mixed. It's exactly the same.

As described above, in the present invention, by adding a water-soluble salt of natural humic acid or regenerated humic acid with a molecular weight of 10 to 10 as a setting retarder, there is almost no pseudo-setting, and according to the increase in the amount added, It is possible to provide a setting retarder that can extend the setting delay time, and by adding such a setting retarder, it is possible to provide a setting retarder that has almost no effect on concrete strength and cement mortar strength.

Patent Applicant Japan Heavy and Chemical Industry Co., Ltd. Agent Rikichi Kawa Procedural Amendment (Spontaneous) September 30, 1980 Kazuo Wakasugi, Commissioner of the Patent Office (Examiner of the Patent Office) 1. Indication of the case 1988 Patent Application No. 1531 + 46 No. 2 / Name of the invention Concrete setting retarder 5 Date of amendment order = Kazusho = Japan - November 2010 - 1 day 1 = Hereafter
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Claims (1)

[Claims] A concrete setting retarder consisting of a water-soluble salt such as natural humin or recycled humic acid with a molecular weight of 103 to 105.