JP2001064058A - Ultra high-early strength cement admixture and cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the workability of concrete and to attain ultra high-early strength and high strength by incorporating a high range AE water reducing agent, bentonite, formic acid, lactic acid, acetic acid and their salts in an admixture. SOLUTION: The high range AE water reducing agent, bentonite and one or more kinds selected from formic acid, lactic acid, acetic acid and their salts are incorporated in the ultra high-early strength cement admixture. As the high range AE agent, a liquid type or a powdery type polycarboxylic acid base can be used and the blending ratio is preferably <=35 pts.wt expressed in terms of solid matter per 100 pts.wt. ultra high-early strength cement admixture. The bentonite preferably has an Si/Al molar ratio of 1.0-3.0 and the blending ratio thereof is 15-80 pts.wt. per 100 pts.wt. ultra high-early strength cement admixture. The blending ratio of formic acid is preferably 5-80 pts.wt. per 100 pts.wt. ultra high-early strength cement admixture. The blending quantity of the ultra high-early strength cement admixture is preferably 1-5 pts.wt. per 100 pts.wt. cement composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-high strength cement admixture and a cement composition mainly used in the civil engineering and construction industries.

[0002]

2. Description of the Related Art In recent years, the performance required of cement and concrete has been increasing more and more, and particularly, research on ultra-high strength and high strength of cement and concrete has been actively conducted. Originally, the strength of cement / concrete largely depends on the water / cement ratio. To reduce the water / cement ratio as much as possible, as specified in JIS A 6204 “Chemical admixture for concrete”, water reducing agent And the use of high-performance water reducing agents is common. However, there is a limit to the reduction of the water / cement ratio, and there is a problem that workability must be sacrificed.

[0003] On the other hand, many methods have been proposed for realizing ultra-rapid strengthening and high strength by promoting the hydration of cement, regardless of the reduction of the water / cement ratio. For example, calcium nitrate, calcium nitrite, calcium chloride, formic acids,
Various methods have been proposed to enhance the strength of cement concrete using accelerators such as sodium nitrate and calcium formate, and lactic acid and its salts (US Pat. No. 34).
No. 27175, JP-A-50-80315, JP-A-50-10998, JP-A-55-71653, U.S. Pat.No. 3,801,338, or British Patent No. 1,252,501 and British Patent No. 1,252,502 etc. ).

[0004]

Further, a concrete in which these accelerators are mixed is used in combination with a high-performance AE water reducing agent to achieve super-rapid strengthening and high strength. However,
Mixing a large amount of high-performance AE water reducer increases the delay,
There is a limit because concrete material separation easily occurs and adversely affects the strength. Thus, the present inventors have made various efforts to solve the above-mentioned problems, and as a result, obtained the knowledge that the above-mentioned problems can be solved by using a specific ultra-high-strength cement admixture, and completed the present invention. I came to.

[0005]

That is, the present invention provides an ultra-fast AE water reducing agent, bentonite, and one or more selected from the group consisting of formic acid, lactic acid and acetic acid. It is a cement cement admixture, and is a cement composition containing cement and the ultra-high strength cement admixture.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

Although the high-performance AE water reducing agent of the present invention is not particularly limited, for example, polycarboxylic acid-based liquid type and powder type can be used. Chemicals' product name "Darlex Super 200", NMB's product name "Leo Build SP-8HS" and Takemoto Yushi's product name "Tupole HP-1"
1 "and the like. In addition, various high-performance AEs
Water reducing agents are commercially available, and both are used.

[0008] The mixing ratio of the high-performance AE water reducing agent is preferably 35 parts by weight or less, more preferably 2.5 to 20 parts by weight, in terms of solid content, in 100 parts by weight of the ultra-high strength cement admixture.
If it exceeds 35 parts by weight, material separation may occur or sufficient early strength may not be obtained.

Although the bentonite of the present invention is not particularly limited, the molar ratio of Si / Al is preferably 1.0 to 3.0, more preferably 1.0 to 2.0. Outside of this range, material separation of concrete may easily occur. As for the particle size of bentonite, a commercially available product can be used as it is.
A sufficient effect can be expected even with a coarse material having a size of about 100 to 350 mesh or less.

The blending ratio of bentonite is preferably 15 to 80 parts by weight, more preferably 25 to 60 parts by weight, per 100 parts by weight of the ultra-high strength cement admixture. Since the proper mixing amount varies depending on the concrete temperature, the mixing amount of the water reducing agent, the unit cement amount in the concrete, and the like, it is difficult to uniformly specify the mixing amount.
If the amount is less than 5 parts by weight, the compounding effect cannot be expected so much.
Exceeding the weight part is not preferred because the water reduction rate of the water reducing agent may be extremely reduced. As the concrete temperature is higher, the unit cement amount is smaller, and the amount of the water reducing agent is smaller, the amount of bentonite tends to be smaller.

The formic acid, lactic acid, acetic acid and salts thereof (hereinafter referred to as formic acids) of the present invention include formic acid, lactic acid and acetic acid,
And salts thereof such as sodium salt, potassium salt, lithium salt, calcium salt, magnesium salt, barium salt, aluminum salt, zinc salt and ammonium salt.

The mixing ratio of formic acids is preferably from 5 to 80 parts by weight, preferably from 10 to 10 parts by weight, per 100 parts by weight of the ultra-high strength cement admixture.
60 parts by weight is more preferred. If the amount is less than 5 parts by weight, sufficient early strength may not be obtained, and if it exceeds 80 parts by weight, sufficient slump holding properties may not be obtained, which is not preferable.

The amount of the ultra-high strength cement admixture of the present invention is not particularly limited, but is usually a cement composition 100 composed of cement and the ultra-high strength cement admixture.
Of the parts by weight, 1 to 5 parts by weight is preferable, and 2 to 3 parts by weight is more preferable. If the amount is less than 1 part by weight, the effects of the present invention, such as early strength and high strength, may not be sufficiently obtained, and even if the amount exceeds 5 parts by weight, further improvement of the effect cannot be expected.

In the present invention, in addition to the high-performance AE water reducing agent, bentonite and formic acids, it is possible to further use a coagulation accelerator if necessary. Examples of the setting accelerator include alkali metal aluminates such as sodium aluminate, potassium aluminate and lithium aluminate, alkali carbonates such as sodium carbonate, potassium carbonate, lithium carbonate, sodium bicarbonate, potassium bicarbonate and lithium bicarbonate. Nitrate and nitrite such as metal carbonate and bicarbonate, sodium nitrate, potassium nitrate, lithium nitrate, calcium nitrate, sodium nitrite, potassium nitrite, lithium nitrite, calcium nitrite, sodium sulfate, potassium sulfate, lithium sulfate Gypsum, dihydrate gypsum, hemihydrate gypsum, anhydrous gypsum, inorganic sulfates such as aluminum sulfate, and aminoalcohols such as calcium hydroxide, calcium oxide, alum, thiocyanate, thiosulfate and triethanolamine. One or two of these It is possible to use a higher, is to further promote super early strengthening and high strength.

As the cement according to the present invention, there are various kinds of Portland cements such as ordinary, fast, super fast, low heat and moderate heat, various mixed cements obtained by mixing blast furnace slag, fly ash and silica with these cements, limestone powder and the like. And alumina cement and the like.

Further, in the present invention, in addition to aggregates such as sand and gravel, an AE agent, a thickener, a rust inhibitor, a frost inhibitor, and a polymer are added to the cement admixture and cement composition of the present invention. One or more of an emulsion, a cement expander, an inorganic phosphate, boric acid and the like can be used in combination within a range that does not substantially inhibit the object of the present invention.

As the mixing device used for producing the ultra-high strength cement admixture and the cement composition of the present invention, any existing stirring device can be used. For example, a tilting mixer, an omni mixer, a V-type mixer can be used. Mixers, Henschel mixers, Nauta mixers and the like can be used. or,
Mixing, each material may be mixed at the time of construction,
Some or all of them may be mixed in advance.

[0018]

The present invention will be described below in detail with reference to examples.

The concrete composition, measuring method and materials used in the examples are shown below. <Concrete Mixing> Based on the concrete mixing shown in Table 1, the concrete mixing is carried out in a room at 20 ° C. by a forced mixing mixer (capacity 100 liters).
60 liters of concrete were kneaded and mixed for 3 minutes, and the slump and the compressive strength of the concrete (φ10 × 20 cm test piece) were measured. <Measurement method> Compressive strength: Measured according to JIS A 1108. Slump test: Measured according to JIS A1101. <Materials> High performance AE water reducing agent a: Commercially available polycarboxylic acid type High performance AE water reducing agent b: Commercially available polycarboxylic acid type High performance AE water reducing agent c: Commercially available polycarboxylic acid type bentonite: Commercial product (A.C.C.) Swelling degree 2 by method
5) Formic acids A: Reagent primary calcium formate Formic acids B: Reagent primary formic acid Formic acids C: Reagent primary sodium formate Formic acids D: Reagent primary potassium formate Formic acids E: Reagent primary lactic acid Formic acids F: Reagents Primary calcium lactate Formic acid G: Reagent primary sodium lactate Formic acid H: Reagent primary potassium lactate Formic acid I: Reagent primary calcium acetate Formic acid J: Equiweight mixture of formic acid A and formic acid F Formic acid K: Equal weight mixture of formic acid A, formic acid F, and formic acid I Cement: Commercially available early-strength Portland cement Sand: Himekawa, Niigata Gravel: Himekawa, Niigata Water: Tap water

[0020]

[Table 1]

Example 1 An ultra-high-strength cement admixture was prepared by changing the blending ratio of bentonite and formic acid A shown in Table 2 to 1: 1 and changing the type and blending amount of a high-performance AE water reducing agent. 2 parts by weight of the ultra-high strength cement admixture was mixed with the concrete, and the slump and the compressive strength of 24 hours and 28 days old were measured. Table 2 shows the results. When a water reducing agent was added to the concrete composition shown in Table 1, a small amount of water was required to obtain the same slump. Therefore, the amount of water was reduced and the slump was adjusted.

[0022]

[Table 2]

The use of the ultra-high-strength cement admixture of the present invention enables good workability (large slump) even with concrete having a low water-cement ratio, and enables the concrete to be prematurely strengthened and to have high strength. It is shown.

Example 2 In the same manner as in Example 1, the compounding ratio of the high-performance AE water reducing agent a and formic acid A shown in Table 3 was set to about 1: 3, and the amount of bentonite was changed to change the ultra-high strength cement admixture. And cement 10
0 parts by weight, 2 parts by weight of ultra-high strength cement admixture was mixed and mixed with concrete, and slump and material age 24 hours,
The compression strength was measured on 28 days. Table 3 shows the results. In addition, in order to obtain the same slump as in Example 1, the unit water amount was adjusted.

[0025]

[Table 3]

It has been shown that the ultra-high-strength cement admixture of the present invention has good workability of concrete, and is capable of ultra-rapid strengthening and high strength even if the amount of bentonite is changed.

Example 3 In the same manner as in Example 1, the mixing ratio of the high-performance water reducing agent a and bentonite shown in Table 4 was set to about 1: 3, and the type and amount of formic acids were changed to obtain an ultra-high strength cement admixture. Was prepared. Cement 1
2 parts by weight of the ultra-high strength cement admixture was mixed with 00 parts by weight and mixed with concrete, and the slump and the compressive strength of 24 hours and 28 days of age were measured. Table 4 shows the results.
Shown in

[0028]

[Table 4]

It has been shown that the use of the ultra-high-strength cement admixture of the present invention makes it possible to improve the workability of concrete and to achieve ultra-rapid reinforcement and high strength.

Example 4 The same procedure as in Example 1 was carried out except that the amount of the ultra-high strength cement admixture of Experiment No. 1-5 was changed as shown in Table 5 with respect to 100 parts by weight of cement. Was. Table 5 shows the results.
Shown in

[0031]

[Table 5]

It is shown that the concrete using the ultra-high strength cement admixture of the present invention has remarkably higher strength for 24 hours and 28 days than the concrete of the comparative example.

[0033]

EFFECT OF THE INVENTION By using the ultra-high strength cement admixture of the present invention, the workability is good (even with a large slump) even with concrete having a low water-cement ratio, and it is possible to make the concrete ultra-high-strength and high-strength. Become.

Claims (2)

[Claims] 1. A high-performance AE water reducing agent, bentonite,
An ultra-high strength cement admixture comprising one or more selected from the group consisting of formic acid, lactic acid, acetic acid and salts thereof. 2. A cement composition comprising a cement and the cement admixture of claim 1.