JP2002356362A - Hydraulic powder composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic powder composition capable of constructing a structure without alkali elution, and displaying an excellent effect of stabilizing process on weak dirt. SOLUTION: The hydraulic powder composition is manufactured as follows that the powder composition containing magnesium oxide powder and magnesium hydrogen phosphate powder as main ingredients, and the weight ratio of MgO/P2 O5 of which is 10.0-23.0 is added with hemihydrate gypsum powder of 0.5-15.0 pts.wt. The powder composition is hardened by reacting with water, and formed into a low alkali hardened body. The ingredient of this hydraulic compact is so water insoluble that its alkali is hardly eluted into the water. Therefore, it is possible to construct an environmentally friendly structure. Furthermore, the stably processing effect of the powder composition on the weak dirt is beter than conventional cement-based composition or lime-based composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The hydraulic powder composition of the present invention contains a magnesium oxide powder and a magnesium monohydrogen phosphate powder as main components, and has a MgO / P ₂ O ₅ weight ratio of 1 to 1.
A hydraulic powder composition obtained by adding 0.5 to 15.0 parts by weight of a gypsum hemihydrate powder to 100 parts by weight of a powder composition of 0.0 to 23.0, without alkali elution. A cured product can be obtained, and it can be used as a structural material for building interior materials, exterior materials, concrete mixed with aggregate, mortar, and the like. Further, it can be used as a soil stabilizing material that exhibits an excellent stabilizing effect on soft soil such as Kanto loam, silt, sludge, and organic soil.

[0002]

2. Description of the Related Art Cement-based compositions, which are common hydraulic compositions, are widely used in buildings and structures as concrete or mortar in which gravel, sand, and reinforcing bars are combined. Portland cement is a representative example of the cement-based composition. When Portland cement is used for a structure, calcium hydroxide released along with the hardening due to the hydration reaction elutes from the hardened material and becomes highly alkaline. The eluted calcium hydroxide reacts with carbon dioxide in the air to generate calcium carbonate, and precipitates on the surface of the cured product, causing problems such as efflorescence. Means for solving these problems include a method of adding a synthetic resin emulsion to reduce the elution of alkali and a method of coating the surface of a cured body with a thermosetting resin to modify the surface. Up is inevitable, has not solved the problem.

[0003] Low-alkali cements include oxychloride cement, oxysulfite cement and phosphate cement. The oxychloride cement utilizes the fact that when a weak alkali metal oxide and an aqueous chloride solution of the metal are mixed, a hydrate of the metal hydroxychloride is generated and hardened (chemical formula (1)). mMO + MCl ₂ → mMO ・ MCl ₂・ nH ₂ O (M: Mg, Zn, etc.) (1) On the other hand, oxysulfite cement uses sulfate instead of chloride. However, both oxychloride cement and oxysulfite cement have poor water resistance and are weak in heat.

[0004] Phosphate cement is used for various oxide powders and
When the acid solution is kneaded, they react to form acidic phosphate.
Utilizes the properties of forming and hardening. High strength hardening
Amorphous structure hydrate must be produced to obtain body
Therefore, weak alkaline or amphoteric and small ionic radius positive
An oxide composed of ions is used. Good room temperature curability
The cation is Al, Zn, Mg, Ca, etc.
Primary phosphate (Mx (H ₂PO₄) y, for example, Al (H₂P
O₄)₃Etc.) or a second phosphate (Mx (HPO₄) y, example
For example, ZnHPO₄, MgHPO₄, CaHPO₄Etc.)
Generate. However, this cement has the disadvantage of using liquid phosphoric acid.
For general use due to poor penetration, poor water resistance, and high price
Is not suitable.

As another phosphate cement, there is a magnesium phosphate cement (phosphomagnesia cement), which is used as an emergency repair material for civil engineering and construction as a fast-setting cement. The main components of magnesium phosphate cement are magnesium oxide (MgO) and ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ), and the reaction is a kind of acid-
It is considered to be a base reaction and can be represented by the following chemical formulas (2) and (3). _{MgO + NH 4 H 2 PO 4} → NH 4 MgPO 4 · H 2 O (2) MgO + NH 4 H 2 PO 4 + 5H 2 O → NH 4 MgPO 4 · 6H 2 O (3) (2) and (3 Finally, as shown in the reaction of the formula, a magnesium ammonium phosphate hydrate is formed and hardened. The reaction is so fast that a retarder is pre-mixed to provide a suitable working time. In addition, since the compound constituting the cured product is an acidic phosphate having poor water resistance, the water resistance is improved by adding silicone or the like. For example, there is a composition disclosed in Japanese Patent No. 2866017, which includes phosphoric acid, a phosphoric acid derivative, a phosphate, and a hydrogen phosphate.
(Potassium salt, magnesium salt, ammonium salt, etc.) or a mixture thereof and MgO, binder phase: 1
0 to 40 parts by weight (MgO / P ₂ O ₅ weight ratio = 1 to 3), aggregate (aggregate or fine aggregate such as silica or alumina): 60 to 9
0 parts by weight, a water repellent (silicone), a setting retarder, and other additives.

Another hydraulic composition is magnesium oxide. The hydraulic property of magnesium oxide is due to its change to magnesium hydroxide by a hydration reaction. Since magnesium hydroxide has a low solubility in water, magnesium hydroxide firstly undergoes a hydration reaction, and once dissolved in water, immediately becomes supersaturated and precipitates as low-crystalline colloidal particles of magnesium hydroxide. The colloidal particles aggregate and form a dense cured product by filling the gaps between the coarse particles.
However, magnesium oxide has problems such as deterioration of workability due to pseudo-coagulation, and destruction due to expansion of the cured product due to delayed hydration of unreacted magnesium oxide remaining in the cured product. It is difficult to use for materials.

[0007] The soil stabilization treatment is a method for improving the mechanical and hydraulic properties of the soil by an ion exchange reaction or a pozzolan reaction between the treated material and the soil particles. Lime compositions are mainly used for Kanto loam and clay soils, and cement compositions are used for silt and sandy soils. Since these compositions are basically highly alkaline, there is a problem of alkaline pollution due to an increase in pH of the improved soil.

[0008] Pozzolan materials are used for organic soils and highly hydrous soils.
(Blast-furnace granulated slag, fly ash, etc.) and a hydration stimulating material (gypsum, sodium sulfate, etc.) are mixed, or a special cement, such as an alumina cement-based composition or an Auyne-based composition, is used. However, the calcium aluminate-based composition and the auyne-based composition have a drawback that they must be expensive because they are manufactured by firing at a high temperature. In addition, since the awine-based composition exhibits quick-setting hardening property in the presence of water, gelation occurs during mixing with soil, resulting in poor workability. In order to compensate for this disadvantage, a method of adding a setting retarder has been adopted, but this causes an increase in cost.
Cement-based compositions and lime-based compositions need to be used in large amounts for organic soils and highly hydrous soils, and are not suitable for practical use.

[0009]

Accordingly, there is provided a hydraulic composition which does not cause alkali elution such as Portland cement, can construct a structure friendly to the natural environment, and exhibits an excellent stabilizing effect on soft soil. Development was required.

[0010]

Means for Solving the Problems As a result of intensive studies in view of the present situation, magnesium oxide powder, magnesium monohydrogen phosphate powder and hemihydrate gypsum powder are mixed at a predetermined mixing ratio and kneaded with water. When the strength of the cured product and the effect of the soil stabilization treatment were examined, the powder obtained by mixing the magnesium oxide powder and the magnesium monohydrogen phosphate powder such that the MgO / P ₂ O ₅ weight ratio was 10.0 to 23.0 Gypsum hemihydrate was added in an amount of 0.5 to 1 based on 100 parts by weight of the composition.
It has been found that a hydraulic powder composition to which 5.0 parts by weight is added exhibits high cured product strength and soil stabilizing effect. In addition, they have found that these powder compositions can solve the above-mentioned problems, and have completed the present invention. Less than,
The present invention will be described in detail.

Magnesium monohydrogen phosphate (MgHPO ₄ )
Is a compound that is hardly soluble in water and has a moderate reactivity, but by adding and kneading appropriate water in the presence of magnesium oxide (MgO), the two react to form a water-insoluble magnesium phosphate aqueous solution. Japanese (Mg ₃ (PO ₄ ) ₂ xH
₂ O, x = 8 or 22). For example, magnesium monohydrogen phosphate is trihydrate (MgHPO ₄ .3H ₂ O)
In the case of, the reaction proceeds according to the following formula. _{MgO + H 2 O → Mg (} OH) 2 (4) Mg (OH) 2 + 2MgHPO 4 · 3H 2 O → Mg 3 (PO 4) 2 · 8H 2 O (5) Mg (OH) 2 + 2MgHPO 4 · _{3H 2 O + 14H 2 O →} Mg 3 (PO 4) 2 · 22H 2 O (6) (5) and _{(6) MgHPO 4 · 3H 2} O 2 molecules relative to the magnesium oxide per molecule as can be seen from equation React, at which time water is incorporated into the crystals. Generated Mg ₃ (PO ₄ ) ₂
When observing the shape of xH ₂ O with a scanning electron microscope,
Basically diameter 0.5 to 1 [mu] m, the columnar crystals of length 10~50μm and (primarily _{Mg 3 (PO 4) 2 ·} 8H 2 O), dense block-like crystals of size of several tens of [mu] m (mainly Mg ₃ (PO ₄ )
₂ · 22H ₂ O) it can be confirmed that are mixed.

Unlike the existing phosphate cement or magnesium phosphate cement, the hydraulic property of the powder composition of the present invention is determined by the hydration reaction of magnesium oxide to form magnesium hydroxide (chemical formula (4)). , And the formation of water-insoluble magnesium phosphate hydrate by the reaction of magnesium oxide and magnesium monohydrogen phosphate (chemical formula (5) and
(6)) Furthermore, it is caused by the formation of gypsum by the reaction of hemihydrate gypsum and water. The hydraulic powder composition utilizing this reaction is a novel one.

As described above, magnesium oxide powder and
Magnesium monohydrogen phosphate powder reacts with water to form Mg₃(P
O₄)₂・ XH₂O columnar crystal block-shaped crystal is generated
I do. Hydration of the excess magnesium oxide from the above reaction
Of magnesium hydroxide fine crystals produced by
The needle-like crystals of gypsum formed by hydration are Mg
₃(PO₄)₂・ XH₂ Invading the voids created between O crystals
Growing or entangled in a net-like manner restricting the movement of other particles
To increase the strength of the cured product in conjunction with a decrease in the water content
Let it. Mg dissolved in water²⁺Ions and OH⁻ Io
Is Mg₃(PO₄)₂・ XH₂Disappears as a component of O
Spent and lowered the pH, the hydration rate of magnesium oxide
The degree of control is reduced and the setting ends slowly without causing false setting
You. After this, water, which is a hydration product of magnesium oxide,
Colloidal particles of magnesium oxide
Needle-shaped crystals of water gypsum gradually remove the voids where water was initially present.
As the densification progresses by filling various parts,
Curing without causing expansion and destruction of the cured body. The present invention
The characteristic of the hydraulic powder composition of₃(PO₄)₂・ XH
₂O crystal, magnesium hydroxide colloidal crystal, dihydrate
The entanglement of the needle-shaped crystals of the plaster is a key factor in
That is the cause.

The cured product has high water resistance, and the pH is lowered because magnesium phosphate and gypsum are acidic.
Therefore, there is no alkali elution from a hardened material such as a cement-based composition, and a structure friendly to the natural environment can be constructed.

The hydraulic powder composition of the present invention contains Mg ₃ (P
O ₄ ) ₂ · xH ₂ O, magnesium hydroxide, gypsum dihydrate to form self-hardening, and soil stabilizing effect by the action of magnesium oxide and the soil component (SiO ₂ , Al ₂ O _3, etc.) pozzolanic reaction Demonstrate. Further, Mg ₃ (P
A large amount of water can be fixed by the generation of O ₄ ) ₂ xH ₂ O and the hydration reaction of magnesium oxide and hemihydrate gypsum.

The magnesium oxide powder and the magnesium monohydrogen phosphate powder, which are the main components of the hydraulic powder composition, are made of Mg
The O / P ₂ O ₅ weight ratio is adjusted to be in the range of 10.0 to 23.0. If the MgO / P ₂ O ₅ weight ratio is greater than 23.0, the amount of generated Mg ₃ (PO ₄ ) ₂ .xH ₂ O is too small, so that Mg ₃ (PO ₄ ) _2.
xH 2 _O, magnesium hydroxide, strength development can not be expected due to the interaction of the crystal between the gypsum. MgO / P ₂
If the O ₅ weight ratio is less than 10.0, the balance between the amounts of Mg ₃ (PO ₄ ) ₂ .xH ₂ O, magnesium hydroxide, and gypsum dihydrate, which are the factors of manifesting the strength of the cured body, is poor, and the strength of the cured body is high. Can not be obtained.

The magnesium oxide powder preferably has a high hydration activity, and is preferably obtained by calcining magnesium carbonate and / or magnesium hydroxide at 1000 ° C. or lower. In consideration of reactivity and workability, the maximum particle diameter is 0.3
mm or less.

The magnesium monohydrogen phosphate powder is anhydrous.
(MgHPO ₄ ), trihydrate (MgHPO ₄ .3H ₂ O),
Four. Pentahydrate (MgHPO ₄・ 4.5H ₂ O), heptahydrate
(MgHPO ₄ · 7H ₂ O) of, preferably one containing any one or more. Magnesium monohydrogen phosphate is a stable substance having low solubility in water and no deliquescence. When mixed with magnesium oxide powder, the reaction does not start unless water is injected, and the reaction between the two proceeds slowly, so that a powder composition excellent in storage stability and workability can be obtained. As another source of phosphoric acid, orthophosphoric acid used in phosphate cement or magnesium phosphate cement
(H ₃ PO ₄ ), water-soluble phosphates, etc. are present, but when these are mixed with magnesium oxide, the reaction proceeds violently, and even if water is not injected, it reacts with magnesium oxide due to moisture in the atmosphere. Is not preferred. In consideration of reactivity and workability, the magnesium monohydrogen phosphate powder preferably has a maximum particle size of 0.3 mm or less.

The gypsum hemihydrate powder has a predetermined MgO / P ₂ O ₅
By adding the magnesium oxide powder and magnesium monohydrogen phosphate powder to the powder composition in a weight ratio to give a proper setting behavior to the composition,
Further, it acts to increase the strength of the cured product due to the dehydration effect due to the hydration reaction of hemihydrate gypsum itself and the hydraulic property. The effect of the addition tends to be more remarkable as the amount of magnesium hydroxide generated at the time of forming the cured product increases, so that the mixing amount of the magnesium monohydrogen phosphate powder can be reduced. Other gypsum sources include gypsum gypsum, but gypsum dihydrate is not suitable for use because it does not exhibit the dehydration effect of the hydration reaction and the effect of increasing the strength of the cured product due to hydraulic properties.

The gypsum hemihydrate powder has a predetermined MgO / P ₂ O ₅
By adding 0.5 to 15.0 parts by weight to 100 parts by weight of the powder composition in which the magnesium oxide powder and the magnesium monohydrogen phosphate powder are mixed so as to have a weight ratio, the effect as a setting accelerator and It has the effect of increasing the strength of the cured body. When the amount is less than 0.5 part by weight, these effects cannot be expected. When the amount is more than 15 parts by weight,
The balance of the substances constituting the cured product is deteriorated, and the strength is reduced. In consideration of reactivity and workability, the hemihydrate gypsum powder preferably has a maximum particle diameter of 0.3 mm or less.

The hydraulic powder composition of the present invention may contain an inorganic compound powder having a low reactivity which does not affect the hydration reaction of the component, that is, a filler.
In this case, 100 parts by weight of the hydraulic powder composition
It is advisable to add up to parts by weight. The mixed composition does not impair the performance as a hydraulic powder composition, and can improve powder properties (fluidity, adhesion, and cohesion) and reduce production costs. When the content of the filler is more than the above-mentioned ratio, the curing performance is not sufficiently exhibited, and thus it is not preferable. The filler is preferably a low-reactivity material that does not undergo a chemical change at room temperature and in wet air, and contains at least one of carbonate, hydroxide, natural mineral products, fly ash, and granulated blast furnace slag as a main component. In the same manner as described above, pulverized to a maximum particle diameter of 0.3 mm or less for use.

As the carbonate, any one or more of calcium carbonate, magnesium carbonate, magnesium hydrogen carbonate and dolomite can be used.

As the oxide, any one or more of iron oxide and aluminum oxide can be used.

As the hydroxide, it is preferable to use any one or more of magnesium hydroxide, iron hydroxide and aluminum hydroxide.

Natural mineral products include any of quartzite, quartz sand, alunite, spinel, feldspar, vermiculite, perlite, pumice, granite, clay, kaolin, talc, bentonite, acid clay, sepiolite, cristobalite, diatomaceous earth, and zeolite. Or more than one can be used.

The hydraulic powder composition of the present invention can be obtained by uniformly mixing magnesium oxide powder, magnesium monohydrogen phosphate powder, hemihydrate gypsum powder and filler powder. Therefore, it is preferable that these materials have a uniform particle diameter in advance. For mixing, equipment that can uniformly mix the powder (V-type mixer, horizontal cylindrical mixer, ribbon-type mixer, conical screw mixer, high-speed flow mixer, etc.) can be selected and used. it can.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific examples of the hydraulic powder composition of the present invention and effects thereof will be described with reference to examples, but the present invention is not limited to the following examples.

Magnesium carbonate (magnesite: MgC
O ₃ ) was sufficiently calcined at 1000 ° C. or lower to obtain magnesium oxide (MgO). The magnesium oxide was pulverized to recover a 0.3 mm sieve. Similarly, magnesium hydrogen phosphate anhydride (MgHPO4), hydrogen phosphate magnesium trihydrate _{(MgHPO 4 · 3H 2 O)} , hemihydrate gypsum _{(CaSO 4 · 0.5H 2 O)} , gypsum (CaS
O ₄ · _2H 2 O), calcium carbonate (calcite: Ca
CO ₃ ), aluminum hydroxide (Al (OH) ₃ ), talc
(As main components, SiO ₂ : 63%, MgO: 30%),
Granite (main component: SiO2: 72%, Al
_{2 O 3: 13%, K} 2 O: 5%, Na 2 O: 5%) recovered 0.3mm sieve passing fraction was ground and used in the following test.

[0029]

COMPARATIVE EXAMPLE 1 8.0 kg of magnesium oxide powder and 2.0 kg of magnesium monohydrogen phosphate trihydrate powder were mixed and stirred with a V-type mixer for 1 hour to obtain 10.0 kg of a powder composition. MgO component and P ₂ O ₅ contained in this powder composition
As a result of analyzing the components, the MgO / P ₂ O ₅ weight ratio was 10.
37. The proportions are shown in Table 1. With respect to this powder composition, the water / powder ratio (%) and the setting time (h) were measured in accordance with JIS R 5201 “Physical Testing Method for Cement”. Table 2 shows the measurement results. In the table, (wt) represents parts by weight. A mortar was prepared by mixing 2 parts by weight of sand (silica sand No. 4) with respect to 1 part by weight of the powder composition, and was subjected to JIS R5201.
According to the “Compression strength test method” described in
m), water / powder ratio (%), specific gravity of compact, material age 7 days and 28
The daily compressive strength (N / mm ² ) was measured. Table 3 shows the measurement results.
Shown in

[0030]

Comparative Example 2 9.0 kg of a magnesium oxide powder and 1.0 kg of a magnesium monohydrogen phosphate trihydrate powder were mixed and stirred by a V-type mixer to obtain 10.0 kg of a powder composition. MgO _/ P 2 _{O 5} weight ratio of the powder composition was 22.62. This powder composition was subjected to a physical test in the same manner as in Comparative Example 1. Table 1 shows the mixing ratio, and Tables 2 and 3 show the measurement results.

[0031]

Comparative Example 3 5.5 kg of magnesium oxide powder, 4.5 kg of anhydrous magnesium monohydrogen phosphate powder, and 0.5 kg of gypsum hemihydrate were mixed and stirred for 1 hour with a V-type mixer to obtain 10.5 kg of a powder composition. Obtained. MgO / P ₂ of this powder composition
The O ₅ weight ratio was 2.63. This powder composition was subjected to a physical test in the same manner as in Comparative Example 1. Table 1 shows the mixing ratio, and Tables 2 and 3 show the measurement results.

[0032]

Comparative Example 4 7.5 kg of magnesium oxide powder, 2.5 kg of anhydrous magnesium monohydrogen phosphate powder and 0.5 kg of gypsum hemihydrate were mixed and stirred for 1 hour with a V-type mixer to obtain 10.5 kg of a powder composition. Obtained. MgO / P ₂ of this powder composition
O ₅ weight ratio was 5.63. This powder composition was subjected to a physical test in the same manner as in Comparative Example 1. Table 1 shows the mixing ratio, and Tables 2 and 3 show the measurement results.

[0033]

Example 1 8.0 kg of magnesium oxide powder, 2.0 kg of magnesium monohydrogen phosphate trihydrate powder, and 0.5 kg of hemihydrate gypsum powder were mixed and stirred for 1 hour with a V-type mixer to form a hydraulic powder composition. 10.5 kg of the product were obtained. M of this powder composition
gO _/ P 2 _{O 5} weight ratio was 10.37. This powder composition was subjected to a physical test in the same manner as in Comparative Example 1.
Table 1 shows the mixing ratio, and Tables 2 and 3 show the measurement results.

[0034]

Example 2 9.0 kg of magnesium oxide powder, 1.0 kg of anhydrous magnesium hydrogen phosphate and 0.5 kg of hemihydrate gypsum powder were mixed and stirred for 1 hour with a V-type mixer to obtain a hydraulic powder composition 10 0.5 kg was obtained. Mg of this powder composition
The O / P ₂ O ₅ weight ratio was 15.77. This powder composition was subjected to a physical test in the same manner as in Comparative Example 1. The mixing ratio is shown in Table 1, and the measurement results are shown in Tables 2 and 3.

[0035]

Example 3 9.0 kg of magnesium oxide powder, 1.0 kg of anhydrous magnesium monohydrogen phosphate powder and 1.5 kg of gypsum hemihydrate gypsum were mixed and stirred for 1 hour with a V-type mixer to obtain a hydraulic powder composition 11. 0.5 kg was obtained. Mg of this powder composition
The O / P ₂ O ₅ weight ratio was 15.77. This powder composition was subjected to a physical test in the same manner as in Comparative Example 1. Table 1 shows the mixing ratio, and Tables 2 and 3 show the measurement results.

[0036]

Example 4 9.0 kg of magnesium oxide powder, 1.0 kg of magnesium monohydrogen phosphate trihydrate powder and 0.5 kg of hemihydrate gypsum powder were mixed and stirred for 1 hour with a V-type mixer to form a hydraulic powder composition. 10.5 kg of the product were obtained. M of this powder composition
gO _/ P 2 _{O 5} weight ratio was 22.62. This powder composition was subjected to a physical test in the same manner as in Comparative Example 1.
Table 1 shows the mixing ratio, and Tables 2 and 3 show the measurement results.

[0037]

Example 5 9.0 kg of magnesium oxide powder, 1.0 kg of magnesium monohydrogen phosphate trihydrate powder and 1.5 kg of hemihydrate gypsum powder were mixed and stirred for 1 hour with a V-type mixer to form a hydraulic powder composition. 11.5 kg of the product were obtained. M of this powder composition
gO _/ P 2 _{O 5} weight ratio was 22.62. This powder composition was subjected to a physical test in the same manner as in Comparative Example 1.
Table 1 shows the mixing ratio, and Tables 2 and 3 show the measurement results.

[0038]

Comparative Example 5 9.0 kg of magnesium oxide powder, 1.0 kg of magnesium monohydrogen phosphate trihydrate powder and 2.0 kg of hemihydrate gypsum powder were mixed and stirred for 1 hour with a V-type mixer to obtain powder composition 12 0.0 kg was obtained. The MgO /
The P ₂ O ₅ weight ratio was 22.62. This powder composition was subjected to a physical test in the same manner as in Comparative Example 1. Table 1 shows the mixing ratio, and Tables 2 and 3 show the measurement results.

[0039]

Comparative Example 6 9.0 kg of magnesium oxide powder, 1.0 kg of anhydrous magnesium monohydrogen phosphate powder and 0.5 kg of gypsum dihydrate were mixed and stirred for 1 hour with a V-type mixer to obtain 10.5 kg of a powder composition. Obtained. MgO / P ₂ of this powder composition
The O ₅ weight ratio was 15.77. This powder composition was subjected to a physical test in the same manner as in Comparative Example 1. Table 1 shows the mixing ratio, and Tables 2 and 3 show the measurement results.

[0040]

COMPARATIVE EXAMPLE 7 9.0 kg of magnesium oxide powder, 1.0 kg of anhydrous magnesium monohydrogen phosphate powder, and 2.0 kg of gypsum dihydrate were mixed and stirred with a V-type mixer for 1 hour to obtain 10.5 kg of a powder composition. Obtained. MgO / P ₂ of this powder composition
The O ₅ weight ratio was 15.77. This powder composition was subjected to a physical test in the same manner as in Comparative Example 1. Table 1 shows the mixing ratio, and Tables 2 and 3 show the measurement results.

[0041]

Comparative Example 8 Comparative Example 1 for magnesium oxide powder
A physical test was performed in the same manner as described above. Table 1 shows the mixing ratio, and Tables 2 and 3 show the measurement results.

[0042]

Comparative Example 9 10.0 kg of magnesium oxide powder and 0.5 kg of hemihydrate gypsum were mixed and stirred for 1 hour by a V-type mixer to obtain 10.5 kg of a powder composition. About this powder composition,
A physical test was performed as in Comparative Example 1. Table 1 shows the mixing ratio
Tables 2 and 3 show the measurement results.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046] In hemihydrate gypsum without addition composition (Comparative Examples 1 and 2), the MgO / P ₂ O ₅ weight ratio increases, cracks had caused by influence of expansion due to magnesium oxide hydration. The powder composition obtained by mixing the magnesium oxide powder, the magnesium monohydrogen phosphate powder, and the gypsum hemihydrate powder had a large compressive strength when the MgO / P ₂ O ₅ weight ratio exceeded 10 (Comparative Examples 3, 4, and 5). Examples 1, 2,
3, 4, 5). The powder composition to which hemihydrate gypsum was added in an external ratio of 20 parts by weight had a poor compressive strength as compared with the examples (Comparative Example 5) because the balance of the substances generated during curing was poor.
The powder composition to which gypsum dihydrate powder is added, generation of cracks due to expansion due to hydration of magnesium oxide is suppressed, but hydraulicity due to hydration reaction of gypsum cannot be expected, due to addition of gypsum gypsum powder No strength developing effect was obtained (Comparative Examples 6 and 7). In the case of magnesium oxide powder, a mixture of magnesium oxide powder and hemihydrate gypsum powder, pseudo-coagulation was caused and the initial setting time could not be measured, and the molded product expanded and cracked after 4 weeks of material age (Comparative Example 8). And 9).

Kuzuu Town, Tochigi Prefecture, Murakashi Lime Industry Co., Ltd. Miyamoto Mine
The topsoil collected in the above is Kanto loam with a density of 1.47 g / c.
m³The water content was 91.8% (external ratio). Against this soil
And hydraulic powders prepared in Examples 1 to 5 and Comparative Examples 1 to 8
Soil stabilization treatment was performed using the body composition. Hydraulic powder set
1m soil³Per 100kg per day
After mixing, collect the treated soil and provide it for uniaxial compressive strength testing.
I made a sample. The dimensions of the specimen are 50 mm in diameter and 1 height.
00mm, compacting by 1.5kg rammer
Performed 25 times / 3 layers. Curing period: 7 days in 20 ° C humid air
The unconfined compressive strength of the specimen is JIS A 1216 "Soil
And the uniaxial compression test method. The created test
Uniaxial compressive strength of body (N / mm²), Water content (%), wet density
(g / cm ²), Dry density (g / cm²Table 5 shows the measurement results
Shown in

[0048]

EXAMPLE 6 7.0 kg of magnesium oxide powder, 1.0 kg of magnesium monohydrogen phosphate trihydrate powder, 2.0 kg of calcium carbonate powder and 0.5 kg of gypsum hemihydrate powder were mixed and stirred for 1 hour with a V-type mixer. To obtain a hydraulic powder composition 10.5
kg. MgO _/ P 2 _{O 5} weight ratio of the powder composition was 17.72. About this powder composition, the soil stabilization process with respect to Kanto loam was performed similarly to Examples 1-5 and Comparative Examples 1-9. Table 4 shows the mixing ratio, and Table 5 shows the test results.

[0049]

Example 7 6.0 kg of magnesium oxide powder, 1.0 kg of magnesium monohydrogen phosphate trihydrate powder, 3.0 kg of aluminum hydroxide powder and 0.5 kg of gypsum hemihydrate powder were mixed with a V-type mixer for 1 hour. Stir to obtain hydraulic powder composition 1
0.5 kg was obtained. MgO / P ₂ O _{5 of} this powder composition
The weight ratio was 15.27. About this powder composition, the soil stabilization process with respect to Kanto loam was performed similarly to Examples 1-5 and Comparative Examples 1-8. Table 4 shows the mixing ratio, and Table 5 shows the test results.

[0050]

Example 8 5.0 kg of magnesium oxide powder, 1.0 kg of magnesium monohydrogen phosphate trihydrate powder, 4.0 kg of talc powder, and 0.5 kg of gypsum hemihydrate powder were mixed and stirred for 1 hour by a V-type mixer. Thus, 10.5 kg of a hydraulic powder composition was obtained. MgO _/ P 2 _{O 5} weight ratio was 15.76. By mixing the talc powder, the fluidity was improved and the adhesion was reduced as compared with other powder compositions. About this powder composition, the soil stabilization process with respect to Kanto loam was performed similarly to Examples 1-6 and Comparative Examples 1-8. Table 4 shows the mixing ratio
Table 5 shows the test results.

[0051]

EXAMPLE 9 4.0 kg of magnesium oxide powder, 1.0 kg of magnesium monohydrogen phosphate trihydrate powder, 5.0 kg of granite powder, and 0.5 kg of gypsum hemihydrate powder were mixed and stirred with a V-type mixer for 1 hour. Thus, 10.5 kg of a hydraulic powder composition was obtained. MgO _/ P 2 _{O 5} weight ratio of the powder composition 10.
37. About this powder composition, Examples 1-6
And the soil stabilization process with respect to Kanto loam was performed like Comparative Examples 1-8. Table 4 shows the mixing ratio, and Table 5 shows the test results.

[0052]

Comparative Example 10 Soil stabilization treatment was performed on Kanto loam using quicklime powder (CaO purity 95%) in the same manner as in Examples 1 to 6 and Comparative Examples 1 to 8. Table 4 shows the mixing ratio, and Table 5 shows the test results.

[0053]

Comparative Example 11 Cement-based solidifying material (CaO: 60%, S
iO ₂ : 19%, Al ₂ O ₃ : 4.7%, Fe ₂ O ₃ :
_{2.5%, MgO: 1.3%,} SO 3: 7.5%) was performed using soil stabilization process for similarly Kanto loam with Examples 1-6 and Comparative Examples 1-8. Table 4 shows the mixing ratio.
Table 5 shows the test results.

[0054]

[Table 4]

[0055]

[Table 5]

In the quicklime and cement-based solidified material, the value of the uniaxial compressive strength with respect to the Kanto loam was small, and in comparison, the hydraulic powder composition of the present invention obtained a strength exceeding both. Strength is improved by the addition of hemihydrate gypsum powder, when MgO / P ₂ O ₅ weight ratio is large, especially the effect becomes remarkable (Comparative Examples 1-4 and Example 1
5). Similar to the result of the mortar test, no strength developing effect was observed by adding gypsum dihydrate powder (Comparative Examples 6 and 7). With respect to the powder composition to which the filler was added, the uniaxial compressive strength decreased as the added amount increased, but higher strength than that of magnesium oxide, quick lime, and cement-based solidified material was obtained (Examples 6 to 9). Magnesium oxide powder, or a mixture of magnesium oxide powder and hemihydrate gypsum powder, higher strength than quick lime and cement-based solidified material was obtained,
It was inferior to the hydraulic powder composition of the present invention (Comparative Examples 8 and 9).

[0057]

The hydraulic powder composition of the present invention is mainly composed of magnesium oxide powder and magnesium monohydrogen phosphate powder, and has a MgO / P ₂ O ₅ weight ratio of 10.0 to ₂ %.
Gypsum hemihydrate gypsum powder was added in an amount of 0.5 to 15.0 parts by weight to 100 parts by weight of a 3.0 powder composition. The cured product obtained from the powder composition has low alkalinity, and a structure that is friendly to the natural environment can be constructed. Further, compared to the cement-based composition, it is expected to be economical in that it can be manufactured at a low cost, and that it exhibits an excellent soil stabilizing effect, and that the amount of the powder composition used in construction can be reduced.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 111: 20

Claims (2)

[Claims] Claims 1. A magnesium oxide powder and a magnesium monohydrogen phosphate powder as main components, and MgO / P
Powder composition 1 in which ₂ O ₅ weight ratio is 10.0 to 23.0
Gypsum hemihydrate gypsum powder was added in an amount of 0.5 to 15.0 based on 00 parts by weight.
A hydraulic powder composition comprising parts by weight. 2. Magnesium monohydrogen phosphate is an anhydride,
Trihydrate, 4. The hydraulic powder composition according to claim 1, which is at least one of pentahydrate and heptahydrate.