JPS6117457A - Concrete composition - 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 (Field of Industrial Application) The present invention relates to a concrete composition (characterized in that it contains a high-performance water reducing agent and an enzymatic dextrin of specific quality).
This is related to two things.

(Conventional technology J) It is said that it is preferable to mix and design concrete so that the unit water volume is as small as possible as long as the workability required for construction is ensured.For this purpose, concrete water reducers (hereinafter referred to as Water reducing agents are widely used, but many of them have air-entraining and/or setting retarding properties, which limits the amount of water they can be added. There is an upper limit.In other words, the water-reducing effect of a water-reducing agent increases as the amount added increases, but in conjunction with this, air-entrainment and/or retardation of setting also increases, creating a limit to the amount of water-reducing agent that can be added. .

By the way, some water reducing agents have substantial water reducing effects that substantially do not have air entrainment properties or set retardation properties, and can achieve a large practical upper limit of the amount of sprinkling.

Such a water reducing agent is called a high performance water reducing agent, and examples thereof include naphthalene sulfonic acid formaldehyde condensate salt, melamine sulfonic acid formaldehyde condensate salt, and the like.

By the way, when constructing high-strength concrete at high temperatures in the summer or continuously constructing for a long period of time, it is convenient to delay the setting of the concrete. In such cases, concrete using a high-performance water reducing agent (in other cases, a setting retarder (hereinafter referred to as a retarder) is used in combination. Phosphates, sugars, oxycarboxylate, etc. are used as retarders). However, their combined use has the following problems.

fa) There is a non-linear relationship between the amount of retarder added 7J+1 and the retardation effect. (The retardation effect increases rapidly when the amount added is large, and the dispersion becomes large, causing the inability to demold at the desired time.)

tb + cement brand (= the variation in the delay effect is wide.

(C) Since the retarder is added outside the high performance water reducing agent, the cost of the admixture used as a whole increases accordingly.

Furthermore, the water reduction effect is not significantly improved by using these retardants in combination.

(Problems to be Solved by the Invention) The invention solves the problems of the above (aJ, (bJ, (CI) The above purpose is achieved by selecting a specific quality enzymatic dextrin described below as a retardant to be used in conjunction with a high performance water reducer. In addition to this, this combination also provided the advantage of synergistic improvement in water reduction effect.

(Means for Solving the Problem) The present invention provides a high performance water reducing agent and (i) Cold water soluble content: 92% by weight or more (ii) Reducing sugar content in terms of glucose: 5 to 30 mJi
Concrete characterized by containing enzymatic dextrin (a specific quality of enzymatic dextrin) with a water bath viscosity (preferably 50 to 100 cps). It is a composition.

In the present invention, the high performance water reducing agent is as described above. In addition, the quality of enzymatic method textrin of specific quality (=terms used are as follows).

In the present invention, enzymatically produced dextrin is one of the dextrins produced by moderately decomposing starch, which is widely used in thickeners, binders, food additives, etc.
Textrin is obtained by hydrolyzing starch using a high-temperature liquefaction method using enzymes. Enzymatic dextrin is
Compared to dextrins produced by other manufacturing methods, such as acid-free roasting and acid roasting, the manufacturing conditions are mild (secondarily, there are low molecular weight components that are undesirable as cement mixtures, and high The content of molecular weight components is extremely low,
It has the characteristics of being homogeneous and its molecules arranged to have uniform lengths.

In the present invention, cold water soluble content refers to sample dextrin 1 (
Bi' was dispersed in 150 ml of distilled water at 21°C,
After maintaining the temperature at B"0 for 7 hours with stirring, the insoluble matter was separated, and the dry solid content obtained by evaporating liquid F was expressed as 8% by weight based on the sample dextrin (2). Furthermore, P
The liquid is evaporated to dryness (in the event of drying, a double film is formed on the entrance surface of the dried solid material, which hinders the further drying process and prevents measurement errors). The so-called filter paper method is used, in which the formed pleated filter paper is immersed in the sample v solution and evaporated to dryness.The reducing sugar content is determined by the Lane-Bynon method (quantitate the reducing sugar from the second method). The obtained value is the table value as the reducing sugar content converted into glucose.

The total content of the high-performance water reducer and the enzyme-produced dextrin of specific quality in the concrete composition of the present invention varies depending on the desired water reduction rate and delay time (delay time relative to setting time of concrete in Blend mixture). % of adhesion to the cement (the dose is generally 11 to 1.0%, preferably 0.8 to 1.0%)
0. t5%. If the amount of stool is less than 0.1%, the water reduction effect will be small, and if it exceeds 1.0%, the retarding effect will be too large or the concrete will tend to separate, which is not preferable.

In the present invention, the high performance water reducer and the enzyme-produced dextrin of a specific quality are mixed into the concrete (in order to incorporate the two into the concrete, it is carried out by means of adding the two together when the concrete is mixed.The adding means is the concrete). Various conventionally known fA addition methods (for example, simultaneous addition, staggered addition, post-addition, etc.) can be applied.
Both may be added at the same time or may be added at different times.

In addition, the effects brought about by the combination of the high performance water reducing agent and the enzyme-produced dextrin of specific quality in the present invention can be brought about not only for concrete but also for cement compositions (cement paste, grout, mortar, concrete, etc.) in general. (Effects of the Invention J) The selection of a specific quality of enzymatic dextrin as a retardant in combination with a superplasticizer provides the following advantages.

(1) Enzyme-produced dextrin of a specific quality has a water-reducing property equivalent to that of a high-performance water-reducing agent, so the addition of a high-performance water-reducing agent and VOW can be reduced by the amount that is added. In other words, the same dextrin can be purchased on a daily basis. Moreover, since the price of the same dextrin is lower than that of a high performance water reducing agent, the cost of the admixture as a whole can be reduced.

1+)! There is a nearly linear relationship between the pre-addition and delayed effects of a constant quality enzymatic dextrin.

(There is little variation in the delay effect depending on the cement brand.

fiiiil water reduction effect is synergistically improved.

This makes it possible to easily and stably achieve the desired setting delay without losing the advantages of high water reduction rate formulations using high-performance water reducing agents. achievable concrete compositions can be obtained.

Furthermore, by using fermentation-accumulated dextrin of a specific quality in combination with a high-performance water reducer, the large drop in slump, which is a drawback of concrete using high-performance water reducers, tends to be improved due to the setting retardation effect.

Generally known as dextrin, it is known that when added to concrete, it exhibits a weak retardation effect. In addition, there is no water-reducing property (2 is equal, so it is not possible to use an internal splitting knife OT as in the present invention (2). The advantages of each of the above-mentioned structures are exhibited for the first time, and those that deviate from these limiting conditions are ineffective in exerting these advantages.In other words, enzymatic dextrin does not have water-reducing properties and retardation properties. small,
Even with enzymatic method dextrin, the cold water oTm content is less than 92% by weight, the reducing sugar content (in terms of glucose, the same below) is less than 5% by weight, and the water bath liquid viscosity (the viscosity of a 50% aqueous solution at 50°0, the same below) Those with j exceeding 500 CpS have both water-reducing and retarding properties (2), and those with a reducing sugar content of more than 30 doublets and an aqueous solution viscosity of 2 Q cps have a small water-reducing effect and are not suitable for retarding additives. The linearity of anger is lost.

In addition, the synergistic improvement in the water reduction effect due to the combination of the above-mentioned high-performance water-reducing agent and a specific quality of enzymatic dextrin is due to the synergistic improvement of the water-reducing effect when the high-performance water-reducing agent is used in combination with 20 to 6 ON teeth and the specific quality of enzymatic dextrin is 30 to 4 (1 piece %). He is a senior author in the range of joint use.

The results of concrete tests conducted to demonstrate the effects of the present invention are shown in Examples 1 and 2 below.

The materials used in this test were the following cuttings.

(B) Cement: Ordinary Portland cement mixed with 8 types (B) Fine aggregate: Oi water-based land sand 11 Coarse aggregate: Crushed stone from Ome (MS=2Qmm) Specified quality enzymatic dextrin (labeled as EDX λ cold water soluble) Minute =
95chi Reducing sugar content - 14% aqueous solution viscosity s o
cps (E) High performance water reducing agent (() Naphthalene sulfonic acid formaldehyde high condensate sodium salt (ligated with N8F) (Il + Melamine sulfonic acid formaldehyde condensate sodium field (written as M8F) This was done using a kneading mixer.

Example 1 An example of the combined use of NSF and EDX is shown below. The concrete formulation is shown in Table 1, and the test results are shown in Table 2.

Table 1 Annotation The figures in the NSF and EDX columns indicate the usage amount, and the total usage amount for both is constant at 5%.

The ZJ EDX rate is the total number of children in two tables (in this case, N
Contains EDX in the total amount of SF and gDX.

Note: hm in the setting time column means hours-minutes.

2) The numerical value in parentheses in the compressive strength column is an index.

Figure 1 shows the relationship between the EDX rate and the setting time in Table 1.2 in a semi-logarithmic graph.As is clear from the figure, there is a linear relationship between the two. , the relationship between the two forms a downwardly convex curve.

The following can be seen from Table 2.

■EDX Significant increase in water reduction effect due to the combination of NSF and EDX within the range of 30 inches (in this case, since the stool volume is the same, j, which appears as an increase in slump, is observed. (Test buttons i and 5) ■EDX rate is outside the above range In this case, the water reduction effect does not change even if the EDX rate changes, indicating that EDX can be replaced with a high performance water reducer on a daily basis.

■EJ) By changing the X ratio, the setting time can be changed linearly.

■As for compressive strength, it increases synergistically compared to the combination of NSF and EDX (2). (However, in Tests A4 and 5, the 8-day strength was lower, but this was because the delay time was large. Example 2 An example of combined use of MSF and EDX is shown below.

The concrete mixture is shown in Table 8, and the test results are shown in Table 4.
FIG. 2 shows the relationship between EDX rate and coagulation time.

2] The total stool dose of MSF and EDX is constant at 0.6%.

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams showing the relationship between EDX rate and coagulation time in semilogarithmic graphs. Figure 1 shows NSF and EDX
In the case of the combined use of SMF and EDX, FIG. 2 shows the case of the combined use of SMF and EDX. Kutsu-iT'AJ Friends Nichiei Star Build Dayus' Ome Shikikai Ne Sat 1st District EDx* (%) Figure 2 EDX car (%)

Claims (1)

[Scope of Claims] High performance water reducing agent and (a) Cold water soluble content of 92% by weight or more (b) Reducing sugar content in terms of glucose 5 to 30% by weight (c) Viscosity of 50% by weight aqueous solution at 50°C 20 to 500c
A concrete composition characterized by containing ps enzymatic dextrin.