JPH0340946A - Cement admixture - Google Patents

Abstract

PURPOSE:To obtain cement admixture imparting high strength and high durability by utilizing aluminum hydroxide, gypsums or pozzolanic material as a main component. CONSTITUTION:A concrete product having high strength and high durability can be obtained by utilizing cement admixture constituted of aluminum hydroxide, gypsums and/or pozzolanic material as a main material and enhancing strength, resistance to salt and resistance to sulfate and inhibiting alkali- aggregate reaction. Both amorphous and crystalline aluminum hydroxide can be utilized. The grain size thereof is preferably regulated to about 2500cm<2> or more Blaine specific surface area. Further anhydrous gypsum II is suitable as gypsums and Blaine specific surface area is preferably regulated to about 3000cm<2> or more. On the other hand, silica hume and blastfurnace slag, etc., are utilized as pozzolanic material and the Blaine specific surface area is preferably regulated to about 4000cm<2> or more. The blending amount thereof is properly regulated to about 0.5-15 pts.wt. aluminum hydroxide, about 1-25 pts.wt. gypsums (expressed in terms of CaSO4) and about 1-20 pts.wt. pozzolanic material for 100 pts.wt. cement.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a cement admixture, and more specifically, it is a cement admixture that provides high strength and high durability, and is used for general civil engineering building structures, concrete products, etc. at room temperature. Or, it relates to cement admixtures used in mortar or concrete manufactured under normal pressure steam curing conditions.

<Conventional technology and its challenges> In recent years, the four components of high-quality cement have been depleted, the firing method has become dry,
While R and O in cement are increasing due to pulverized carbonization of fired fuel, cracking due to alkaline aggregate reaction due to depletion of aggregate and deterioration of quality has become an issue.

In addition, with the progress of ocean development, the development of salt-resistant and sulfate-resistant mortar or concrete is becoming more important, but chemical methods, physical methods, and a combination of these methods can be used to solve these problems. A method is proposed.

The chemical method is a method that uses blast furnace slag, which suppresses the alkaline aggregate reaction and fixes penetrating chloride and sulfate ions in the form of ettringite and Friedel salt, preventing further penetration. It is well known that the prevention of such damage is well known, and it is recommended that 40 parts by weight or more of blast furnace slag be added to the total of 100 parts by weight of cement and blast furnace slag.

In addition, the physical method is a method that uses silica hume, finely powdered fly ash, gypsum, etc. to seal the movement of R20 and slow down the penetration of chlorine ions and sulfate ions by increasing the strength and density. is proposed. For example, using ultrafine powder such as silica hume and a high-performance water reducing agent (Japanese Patent Laid-Open No. 61-21950), or using ■-type anhydrite and a siliceous substance (Japanese Patent Laid-Open No. 53-252).
9) have been proposed.

In addition, as a method of using both of them together, a method has been proposed in which high strength and high durability are achieved by pulverizing blast furnace slag and using a large amount of 15μ or less (Japanese Patent Application Laid-Open No. 61-281057 Publication No.).

However, methods that use large amounts of blast furnace slag are thought to lack oxygen because blast furnace slag is generated in a reducing atmosphere, and it is assumed that it is subject to not only carbonation by CO2 gas but also oxidation. For example, 1,000
Even high-strength concrete of about kgf/cTA has been observed to turn white from the outside to the inside, leading to concerns about rusting of reinforcing bars.

Furthermore, in the case of high strength mainly using gypsum, calcium aluminum oxide 1 in cement is replaced with stable ettringite (3CaO-A1203, 3CaSO4, 32H).
In particular, Friedel salt (3CaO・AlzOi・CaC) is fixed as chlorine ion penetration.
Since the chemical adsorption ability is lost as Iz.101hO), significant improvement in salt tolerance cannot be expected.

With silica substances such as silica fume, there is a problem in that the silica substance itself reacts with R20 and expands, particularly with regard to suppressing the alkali aggregate reaction, and depending on the amount blended, the expansion may increase.

As a result of various studies, the present inventors have obtained the knowledge that by using a specific composition, the conventional problems as described above can be solved and a cement admixture with high strength and high durability can be obtained. The present invention has now been completed.

<Means for Solving the Problems> That is, the present invention provides a cement whose main components are aluminum hydroxide, gypsum and/or pozzolanic substances. It is made of Konwa wood.

The present invention will be explained in detail below.

As for the aluminum hydroxide used in the present invention, either amorphous or crystalline aluminum hydroxide≧ can be used.

Amorphous aluminum hydroxide is produced as a by-product during aluminum processing, or as an intermediate in the production of alumina gel, etc., and is often in the form of a wet cake or sol containing a large amount of water. Rather than using them dry, it is preferable to use them in the form of a slurry by adding an appropriate amount of water, or after wet-pulverizing the slurry.

Crystalline aluminum hydroxide is preferably commercially available for industrial use.

The particle size of aluminum hydroxide appears to be smooth and fine, but when the Blaine specific surface area is measured, it is 1,000c.
+a/g, and as it is, it is difficult to react at least below the temperature of normal pressure steam curing conditions. From the viewpoint of improving various durability, it is preferably 2,500 cffl/g or more.

The gypsums used in the present invention include trihydrate, hemihydrate, ■type anhydrous, and ■type anhydrous gypsum, and include naturally produced gypsum, chemical gypsum such as phosphoric acid, excretion, hydrofluoric acid gypsum, or heat-treated gypsum. The product obtained can be used, and is not affected by the types of impurities or stars that are normally included. And, from the standpoint of density and high strength, ■ type anhydrous granola
Particularly, it is preferable to use rice that has been crushed to a Blaine specific surface area of 3,0 OOc+fl/g or more because it is best under normal temperature or normal pressure steam curing conditions and usually leaves no unreacted substances.

Furthermore, type anhydrous gypsum is produced in large quantities as a by-product from the hydrofluoric acid generation process, so it can be used as is or with CaC0, Ca (
OH)! It is most convenient to use free-H2SO, which has been neutralized with CaO or the like.

The pozzolanic materials used in the present invention are those that easily cause a pozzolanic reaction, such as silica fume, diatomaceous material, Aerosil, burned ash of silicified wood such as straw ash, blast furnace slag, and flyash.

Commercially available products can be used as they are, but the finer the blast furnace slag or fly ash, the better.
A fine powder of about 000 to 10,000 cbo/g is more preferable.

When blending the cement admixture of the present invention using each of the above-mentioned components, in the system of aluminum hydroxide and gypsum, aluminum hydroxide should be added to 0.1-100 parts by weight of aluminum hydroxide.
5 to 15 parts by weight, gypsum is 1 to 2 parts by weight in terms of CaSO4
A range of 5 parts by weight is preferred.

Sencolas increase the reactivity of aluminum hydroxide and improve its salt tolerance. On the other hand, aluminum hydroxide, in an appropriate amount, exhibits an interaction that promotes the increase in strength of sencolas.

When the ratio of aluminum hydroxide used increases, salt resistance improves, and when the ratio of gypsum used increases, higher strength can be obtained than when gypsum is used alone.

If aluminum hydroxide and Sencora are less than 0.5 and 1 part by weight, the effect of use will be small, and if they exceed 15 and 25 parts by weight, respectively, the effect of improving salt resistance will be reduced, etc. Economically unfavorable. Preferred ranges are 1 to 10 parts by weight of aluminum hydroxide and 2 to 20 parts by weight of Gypsum 'R to 100 parts by weight of cement.

Furthermore, among the gypsums, half-water gypsum and type 2 water gypsum may cause false setting depending on the amount used. In that case, pseudo-coagulation can be achieved by blending an organic acid such as citric acid, malic acid, tartaric acid, gluconic acid, heptonic acid, or their salts in an amount of at most 0.3 parts by weight per 100 parts by weight of cement. can be suppressed without affecting salt resistance or strength.

In addition, in the system of aluminum hydroxide and pozzolanic materials, aluminum hydroxide not only improves salt resistance, but also silica hume and other pozzolanic materials can be used in low amounts of around 5 parts by weight per 100 parts by weight of cement. When combined with blast furnace slag, the amount of blast furnace slag used is required to suppress the alkali aggregate reaction that tends to occur in This reduces the problems such as oxidation mentioned above.

The ratio of aluminum hydroxide and pozzolan used is 100% cement.
0.5 to 15 parts by weight and 1 to 20 parts by weight, respectively, are preferable, and if they are less than 0.5 parts by weight and 1 part by weight, the effect of use will be small, and if they exceed 15 parts by weight and 20 parts by weight, respectively. When used, it is not preferable because it has little elongation with respect to effects such as salt tolerance and lacks symmetry.

Preferred ranges are 1 to 10 parts by weight of aluminum hydroxide and 2 to 15 parts by weight of pozzolan to 100 parts by weight of cement.

Furthermore, higher strength and higher durability can be achieved with a cement admixture system containing aluminum hydroxide, gypsum, and pozzolanic materials.

The usage ratio of each component is 0.5 to 15 parts by weight for aluminum hydroxide and CaS for gypsum to 100 parts by weight of cement.
It is preferable to use 1 to 25 parts by weight of O4 and 1 to 20 parts of pozzolan by weight. If the amount is less than the lower limit, the effect of use will be small, and if the amount exceeds the upper limit, it will improve strength and various durability. The increase in effectiveness is small, making it economically unfavorable. Preferred ranges are 1 to 12 parts by weight for aluminum hydroxide, 2 to 20 parts by weight for gypsum, and 2 to 15 parts by weight for pozzolanic materials.

The method for producing the cement admixture of the present invention is to use commercially available products such as silica hume, diatomaceous earth, Aerosil, and incineration ash of petrified wood, which are finely divided, with each component adjusted to an appropriate Blaine specific surface area. Those with high activity may be mixed as is, or may be mixed and then ground.

Furthermore, regarding the method of adding cement admixtures to mortar or concrete, each component may be added separately and at the same time during kneading, mixed in advance with cement, or added as a mixture. Alternatively, each component may be dispersed in kneading water and added in the form of a slurry. When amorphous aluminum hydroxide is used, it is preferable from the viewpoint of performance and economy to mix each component to form a slurry and use it as a cement admixture.

Cement of the present invention l-? When producing mortar or concrete using the H additive material, admixtures or admixtures such as various water reducing agents and expansion agents can be used in combination, and in particular, the combined use of high performance water reducing agents is preferred in order to obtain high strength.

A high-performance water reducing agent is a surfactant with a large dispersion ability that does not cause excessive delay in condensation or excessive air entrainment even when added in large amounts, and is a surfactant that does not cause excessive condensation delay or excessive air entrainment even when added in large amounts. These include salts of condensates, and those whose main ingredients are high-molecular-weight trigenine sulfonates, polycarboxylate salts, and the like.

Specifically, for example, the product name “Mighty 150” manufactured by Kao ■
1, Denki Kagaku Kogyo q-gradation product name rFT-500J, Hozolith Bussan Co., Ltd. product name IN L-4000J, and the like.

The amount of high-performance water reducing agent used is not particularly limited, but it is 0.2 parts by weight of cement in terms of solid content.
About 2 parts by weight is preferred.

Further, the combined use of an expansive material is preferable from the viewpoint of producing a concrete member with high durability and high bending strength.

Expansive materials are currently CaO-based and CaO-Al2O, -5o.
, systems are commercially available, and the former is, for example, "Onoda Expan" manufactured by Onoda Cement QtJ, and the latter is, for example, "Denka C3A #20J" manufactured by Denki Kagaku Kogyo ■, but is limited to these. It's not a thing.

In addition, as the cement used in the present invention, various Portland cements such as normal, early strength, super early strength, medium heat, white, etc., and mixed Portland cement mixed with silica and fly ash can be used.

<Example> The present invention will be explained below with reference to Examples.

Example 1 Using the concrete composition shown in Table 1, the powder degree of amorphous aluminum hydroxide sludge from an aluminum processing factory and crystalline aluminum hydroxide sludge commercially available for industrial use was changed, and gypsum and The compressive strength of the concrete and the permeability of chloride ions were tested after curing with atmospheric pressure steam.

For normal pressure steam curing, φ10 x 20c was cured for 5 hours beforehand.
Ra specimen was heated to 65°C at 15°C/h,
After holding for 4 hours, it was allowed to cool naturally.

The compressive strength is the one-day strength after demolding the next day, and the permeability of chloride ions is determined by immersing the specimen in a 3% NaCl aqueous solution immediately after demolding.
The amount of chlorine ions immersed in the material after 6 months of age was measured. To measure the amount of chlorine ions, measure the center of the concrete using a φ1010X
After drying at 200''C, the entire amount was pulverized and quantified by fluorescent X-ray analysis.

The results are shown in Table-2.

In addition, the cement admixture was replaced by sand and volume in parts by weight relative to 100 parts by weight of cement. Further, gypsum was added in terms of Ca5O, and when adding gypsum (C) and m (Gypsum), 0.05 parts by weight of citric acid as a reagent was used in combination with 100 parts by weight of cement.

In addition, amorphous aluminum hydroxide was prepared by adding the same weight of water and wet-pulverizing the slurry using a porcelain pot grinder to obtain a slurry of 7.25% by weight as aluminum hydroxide.

<Materials used> Cement = Portland cement, Denki Kagaku Kogyo■
Sand production: Niigata prefecture Himeyo Ubukawa sand crushed stone: Crushed stone Water reducing agent: High performance water reducing agent, Denki Kagaku Kogyo ■Product name: Denka F T-50OJ Main bokun naphthalene sulfonic acid formaldehyde condensate aluminum hydroxide-A: Amorphous Quality aluminum hydroxide, manufactured by YKK Corporation, Alx Sludge crystal water 5%, solid content 9.5%, free water 85.5% weft cake shape - B: Crystalline aluminum hydroxide, before pulverization, Blaine specific surface area 2,000 cnl/g〃-C
: 〃2,500〃 D: 〃3. OOO〃 〃 -E: 〃 4. OOO
ll〃 -F: 〃 6,0
00 〃〃-G: 〃11,000〃 Gypsum - A: ■ Type anhydrous gypsum (fluoric acid gypsum) Blaine specific surface area 6,0OOc/g-B: Dihydrate gypsum (excavated gypsum) Blaine specific surface area 6, 500 cffl/g - C: Hemihydrous gypsum, treated at 150°C before draining, Blaine specific surface area 10,000 or more - 2: ■ Type anhydrous gypsum, heat treated at 200°C before draining, Blaine specific surface area 10. 000 or higher aluminum hydroxide has a Blaine specific surface area of 2,500 cTA/g or more when used in combination with gypsum. A higher value is shown in the compressive strength than in the case of adding the same type alone. Aluminum hydroxide has effects on compressive strength and salt resistance starting from 0.5 parts by weight, but even if it is added in excess of 15 parts by weight, no increase in salt resistance can be expected, and the compressive strength will actually decrease significantly. is expected.

When gypsum and aluminum hydroxide are used in combination, if the aluminum hydroxide is about 5 parts by weight, the compressive strength and salt resistance will improve from 1 part by weight or more, but if it is added in excess of 25 parts by weight, However, the compressive strength and salt resistance tend to decrease slightly, and even if the aluminum hydroxide is increased to 15 parts by weight, the salt resistance is improved, but the compressive strength is greatly reduced.

Example 2 The central part of the 1-day-old specimens of Experiment Nos. 1-1 to 1-7 was cut into φ1010×2, and the clearance of the brown crusher was adjusted so that the maximum particle size was around 0.25[11[11]. The whole amount was put into a 3% Na5O aqueous solution 11, and the mixture was cured at 20'C for 3 days, filtered, washed with water, dried at 200'C, finely pulverized, and fluorescent. Chemisorbed sulfate ions were quantified by xvA analysis.

In addition, the amount of adsorbed sulfate ions was subtracted by using Experiment No. 1-1 before immersion as a blank. The results are shown in Table-3.

Blaine specific surface area of surface aluminum hydroxide is 2,500 cnl/
It is shown that the finer the particle size is, the larger the amount of sulfate ions adsorbed, and the greater the effect of blocking infiltrating sulfate ions.

Example 3 Compressive strength when the specimens of Experiment No. 1-1 to 1-7 were subjected to standard curing for 28 days without steam curing, and after that, 3% N
It was immersed in the aC1 aqueous solution in the same manner as in Example 1, and the amount of chlorine ions permeated was measured. The results are shown in Table 4.

As is clear from Table 4, even at room temperature, aluminum hydroxide with a Blaine specific surface area of 2,500c+fl/g or more reacts and improves the compressive strength and salt resistance when gypsum is added alone. , becomes more pronounced as the Blaine specific surface area becomes larger.

Example 4 The types and amounts of aluminum hydroxide and pozzolan used in Example 1 were changed as shown in Table 6, and 71,800 g of cement was prepared.
800 g of sand 1 having the particle size shown in Table 5 and 400 g of a 1N NaOH solution were mixed, and the amount of permeated chlorine ions, the amount of expansion due to the alkali aggregate reaction, and the compressive strength were measured.

Table-5 (%) Specimens for chloride ion content and compressive strength are 4X4X16cm
, the specimen for alkali aggregate reaction test is 4X4X16Cm
A specimen with gauge plugs for expansion measurement embedded in both ends was used.

The curing method is to mold the mortar indoors at 20 ± 3°C and RH 80% or more, camp for about 6 hours, and then dry it for 15 hours.
The temperature was raised to 65°C at a rate of °C/h, maintained at that temperature for 4 hours, and then allowed to cool naturally and demolded the next day.

The amount of chloride ions was determined in the same manner as in Example 1 by immersing the sample in a 3% NaCl aqueous solution immediately after demolding, and after 3 months cutting out the central part of the sample into a 4 x 4 x 2 cm piece.

In the alkaline aggregate reaction test, the demolded specimen was held at 20±3°.
After curing for another 24 hours in C water, the substrate was cured for 6 months at 40±2°C and RH 95% or higher, and the amount of expansion was measured. Moreover, the compressive strength was measured when the material was 1 day old. The results are shown in Table-6.

In addition, each component of the cement admixture is replaced by the weight of the sand part, and the weight part is based on 100 weight parts of cement.Even if the softness of the mortar changes, when actually mixing mortar or concrete, adjust it with a water reducing agent. I ignored it in this case because it can be done.

<Materials used> Sand: Pozzolanic mixture of 90 parts by weight of natural sand with the particle size shown in Table 5 and 10 parts by weight of opalescent silica from Iwo Jima -a Nijirikahium, manufactured by Nippon Heavy and Chemical Industry ■ -b: Aerosil, Japan Product name made by Aerosil■
Aerosil 50J 〃 -c: Diatomaceous earth, manufactured by Showa Kagaku Part name FS P
FJ pulverized product, 63 μ or less〃 -d: Straw ash, rice straw incineration ash, -〇2 blast furnace slag, Blaine specific surface area 6.500 cffl/g manufactured by Yoshibament Co., Ltd.〃 -f: Fly ash, Tokiwa Keiryu Sangyo Co., Ltd. made, Blaine specific surface area 6,50
0 c self/g Other than the above, the same as Example 1.

As is clear from Table 6, when the plain specific surface area of aluminum hydroxide is 2,500c+f/g or more, the finer the aluminum hydroxide, the more effective it is to suppress penetration of chlorine ions and alkali aggregate reactions, etc.
Each effect, such as the strength development effect, is clearly shown.

Aluminum hydroxide exhibits an effect when added at 0.5 parts by weight or more, and pozzolanic substances exhibit effects when added in combination with alkaline hydroxide at 1 part by weight or more.

Example 5 As shown in Table 7, a test similar to Example 1 was conducted using various combinations of the amounts of each component of the cement admixture. The results are also listed in Table-7.

In addition, the volume of each component of the cement admixture was replaced with that of sand by parts by weight based on 100 parts by weight of cement.

In addition, when the slump did not fall within the design value, a water reducing agent was added to adjust the slump without changing the water-cement ratio.

As is clear from Table 7, high-strength and highly durable concrete can be easily obtained by using appropriate amounts of aluminum hydroxide, gypsum, and pozzolanic materials in combination.

Example 6 Using the concrete of Experiment Nos. 1-1 to 1-7 and 5-5, PC resistors with an outer diameter of 300 aun, a thickness of 60 mm, a length of 4 m for bending moment and a length of 1 m for compression were regularly installed. The bottom was shaped by the method and cured under the same steam curing conditions as in Example 1. Thereafter, a bending test and a compression test were conducted after the air-drying material was aged for 7 days. The results are shown in Table-8.

In addition, for the reinforcement of PC resistance, the straight reinforcement is high-frequency heat wire■
The manufactured PC steel rods are φ13MXd pieces and φ11mmXd pieces, the spiral reinforcement is made by inserting φ3fflfll steel wires at 10cm intervals, and the initial tension stress of the PC steel bars is 10.150kgf/c.
+l.

Example 7 The concrete used in Example 6 was further treated with 13 parts by weight of the commercially available expansive material Onoda Expan J manufactured by Onoda Cement ■, based on the cement, and the same steam curing conditions as in Example 1 were used. A humid tube was prepared by centrifugal forming according to a conventional method, and an external pressure strength test was conducted after 7 days of air-drying.The results are shown in Table 9.

The Huyum tube has an inner diameter of 100 mm, a thickness of 82 mm, and a length of 2,430 mm, and the reinforcement is straight bars with a reinforcing bar ratio of 0.
．． 26%, double spiral muscle and 1.49% A-type tube.

Table 9 Example 8 The concrete of Example 6 was centrifugally formed using a conventional method, and poles were made under the same steam curing conditions as Example 1. After 7 days of air drying, a bending test was performed. I did it. The results are shown in Table-10.

The pole has a crack design load of 350 kgf and a failure design load of 700 kgf or more, is 13 m long, and has an uncalibrated diameter of 1.
90an A type, PCjlA rod φ7.4 x 8 pieces, RC
Reinforcing bars φ7.4×4 straight bars and spiral bars were φ3mm iron wires installed at a pitch of 100mm.

In addition, the initial tension stress of the p, cm bar is 10,150
It was carried out at kgf/C crawl.

Table 10 <Effects of the invention> As shown in the examples above, the combined use of aluminum hydroxide and gypsum and/or borazone improves strength, salt resistance, sulfate resistance, etc. It has been shown to inhibit the reaction. For example, high strength and high durability of concrete products such as concrete piles, humid pipes, and poles can be easily obtained, and effects such as salt resistance are recognized even when cured at room temperature, and can be applied to general civil engineering and building structures. Show what you can do.

Claims (1)

[Claims] A cement admixture whose main components are aluminum hydroxide, gypsum and/or pozzolanic substances.