JPH0412043A - Hydraulic binder - Google Patents

Abstract

PURPOSE:To obtain a hydraulic binder having a high initial strength without deteriorating a long-period strength by adding an alkali metallic compound to fine granulated blast furnace slag powder, activating the aforementioned blast furnace slag powder and blending the resultant alkali-activated slag with hydrous Mg inosilicate. CONSTITUTION:A hydraulic binder is obtained by adding an alkali metal hydroxide, carbonate or silicate in an amount of 1-10 pts.wt. expressed in terms of NaO2O to 100 pts.wt. fine granulated blast furnace slag powder having >=3000cm<2>/g Blaine specific surface area and acitvating the above-mentioned blast furnace slag powder. The hydraulic binder contains 0.1-10wt.% hydrous Mg inosilicate (a compound expressed by the formula and sepiolite which is a natural mineral is normally used) in the resultant alkali-activated slag. Although mortar using the alkali-activated slag as a binder has conventional disadvantages in deteriorating a long-period strength, mortar or hardened products of concrete with a high initial strength and hardly any deterioration in the long-period strength can be obtained by adding the hydrous Mg inosilicate Thereto. the mortar of concrete using the aforementioned binder has hardly any shrinkage in hardening.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hydraulic binder, and more specifically, the present invention relates to a hydraulic binder, and more specifically, it is made by activating granulated blast furnace slag powder with an alkali metal hydroxide, carbonate, or silicate. This invention relates to a hydraulic binder that prevents long-term strength loss and reduces shrinkage in alkali-activated slag.

[Conventional technology]

Granulated blast furnace slag powder has latent hydraulic properties, so when an alkaline stimulant is added, it is activated and develops hydraulic properties. Therefore, it is expected to be used as a raw material for binding materials for mortar and concrete, but in reality, blast furnace cement is only widely used. However, although blast furnace cement has various advantages over Portland cement, it has the disadvantage of low initial strength, which limits its uses.

On the other hand, mortar made by kneading granulated blast furnace slag powder with water and using alkali-activated slag as a binder, which is made by activating fine powder of granulated blast furnace slag with alkali metal hydroxide, carbonate, or silicate, has excellent early strength and high strength. Although it depends on the curing conditions, the compressive strength is usually about 750 kgf/cn for 3 hours after kneading.
Approximately 300 kg f / cffl in 1 day, wood age 2
It was about 1.000 kgf/afl in 8 days, and expressed in terms of bending strength, it was 15 kgf/ctA in 3 hours after kneading.
The yield is about 45 kgr/cf+ at 1 day old and about 110 kgf/d at 28 days old.

This has long been known as a hydraulic binder with excellent early-strengthening properties, and mortar that is commercially available as super-fast hardening cement and uses Irushet cement as a binder has a compressive strength of 500 kgf/ct1 at 28 days of age. degree, bending strength is 8
It is inferior in terms of high intensity expression at around 0 kg f /crA,
The price is high, and the mortar that uses ordinary Portland cement and keeps the water-cement ratio to about 26-28% to achieve high strength has a setting time of 2 hours at the beginning and 3 hours at the end.
Considering that it takes a long time and does not develop strength within 3 hours after kneading and is inferior in terms of early strength, alkali-activated slag is
It can be seen that the strength development up to 8 days is extremely excellent.

However, mortar using alkali-activated slag as a binder has the disadvantage that its long-term strength, especially its bending strength, decreases significantly. It was found that the bending strength decreased to about 60 to 70% of the bending strength after 28 days.

As a solution to this drawback, methods of adding inorganic additives such as clinker powder and alkali metal sulfates, and methods of adding cement water reducing agents have been proposed, but none of them are sufficiently effective (Japanese Patent Publication No. 6310109 Publication, JP-A-55
-162456).

(Problems to be Solved by the Invention) An object of the present invention is to provide a hydraulic binder having high initial strength and no decrease in long-term strength.

(Means for solving ila) The present inventor conducted research to solve the above problems and discovered that the cause of the long-term strength reduction of mortar using alkali-activated slag is the capillary tubes formed in the hardened mortar. They presumed that this was due to shrinkage due to dehydration, and found that this could be solved by adding a substance that has water retention properties and undergoes a hydration reaction under strongly alkaline conditions, and completed the present invention.

That is, the present invention has a Blaine specific surface area of 3000 cd/
For alkali-activated slag activated by adding 1 to 10 parts of alkali metal hydroxide, carbonate, or silicate in terms of Na and Q to 100 parts by weight of pulverized blast furnace slag of 100 parts by weight or more. , hydrated inosilicate of magnesium from 0.1 to
This is a hydraulic binder characterized by containing 10% by weight.

The present invention will be explained in more detail below.

The pulverized blast furnace slag powder referred to in the present invention is obtained by pulverizing granulated slag obtained by rapidly cooling and crushing blast furnace slag, which is a by-product when producing pig iron in a blast furnace, and has a Blaine specific surface area of 3000 cd/g. That's all. 3000cff
If it is less than l/g, the strength development is very weak. On the other hand, although there is no particular upper limit, the higher the content of over-pulverized components, the greater the drying shrinkage, so depending on the pulverization method, -
For boat fishing, 8000 cd/g or less is preferable.

The alkali-activated slag referred to in the present invention is activated by adding an alkali metal hydroxide, carbonate, or silicate to pulverized blast furnace slag powder. The amount added is 1 to 10 parts by weight in terms of Na2O per 100 parts by weight of pulverized blast furnace slag powder. Even if it is less than 1 part by weight or more than 10 parts by weight, strength development is poor.

The hydraulic binder of the present invention is made by adding hydrated inosilicate of magnesium to alkali-activated slag as a long-term strength deterioration preventive agent. A specific example of a substance containing hydrated magnesium inosilicate is the natural mineral Seviolite. Seviolite is produced in Turkey, China, the United States, and other countries, and is mainly used in the building materials field as a thickening agent for wall materials and insulation materials, and as a material for early demolding.

Seviolite is S i +zMge O3o (OHz
)a, hydrated inosilicate mag Z, which is shown by the chemical formula of 8H2O, is mainly composed of silium, and an example of the chemical composition is 5iO752-58%, Mg015-25%, and a part of MgO is A1 .0, 0.5-2%, Fez
O: substituted with IO, 5-3%, with Ca as an impurity
b, Na2O, contains a small amount of O, etc. Seviolite is 0.2 to 5 mm long, 100 to 300 mm long, and 50 mm thick.
It has a single crystal structure that is fibrous and has voids, and because of this structure, it has special adsorption, water absorption, and adhesive properties, making it particularly effective as a material for preventing long-term strength loss.

The true specific gravity of Seviolite is said to be 2.0 to 2.3, but the dry product used for practical purposes contains about 10% water, and the bulk specific gravity is about 0.6, which is higher than the water content of magnesium. The amount of inosilicate added as a long-term strength reduction prevention material is 0.1 to 10% by weight, preferably 0.5 to 3% by weight of the alkali-activated slag. If it is less than 0.1 parts by weight, the effect of preventing long-term strength reduction is small, and if it exceeds 10 parts by weight, the viscosity of the mortar will increase and workability will be adversely affected, which is not preferable.

In addition, various additives may be added to the hydraulic binder of the present invention, for example, in an amount of about 20 parts by weight or less per 100 parts by weight of pulverized blast furnace slag powder. Specifically, materials with latent hydraulic properties such as fly ash and steelmaking slag powder, cement additives such as talin powder, cement m water agents and antifoaming agents, and water-soluble polymers such as methylcellulose and polyvinyl alcohol are used. May be added. In particular, various performances can be improved by using appropriate amounts of cement additives.

The hydraulic binder of the present invention has the same or better performance as a binder for mortar and concrete than ordinary Portland cement, which is currently widely used, and has particularly excellent acid resistance and heat resistance. It can be expected to be used in a wide range of fields. Especially when used as a structural material,
The effect of magnesium hydrated inosilicate as a material that prevents long-term strength loss becomes significant from around 2 months of age, which overcomes the fatal flaws of conventional alkali-activated slag, such as long-term strength loss and large shrinkage. As a result, the quality and stability of the cured product are high.

〔Example〕

The present invention will be explained in detail below.

Example 1 100 parts by weight of pulverized blast furnace slag powder with a Blaine specific surface area of 5120 cd/g, 23 parts by weight of sodium metasilicate, 1 or 2 parts by weight of sepiolite, 1.2 parts by weight of a cement water reducer, and 2.5 parts by weight of an antifoaming agent. 200 parts by weight of charcoal sand as a fine aggregate and mortar mixed with 42 parts by weight or 45 parts by weight of water, respectively, were poured into a double formwork of 4 x 4 x 16 cm. A test specimen was created using the following equipment.

Each specimen was cured under humid conditions at a temperature of 20°C and a humidity of 95%, and was removed from the mold after 1 day of age. After that, the specimen was sealed in a plastic bag and cured to the specified age. .

For specimens that have reached each material age, J I 5-R520
1, the bending strength and compressive strength were measured.

The chemical compositions of the used granulated blast furnace slag powder and sodium metasilicate are shown in Tables 1 and 2. Shown in the table.

Comparative Example 1 The same procedure as in Example was carried out except that sepiolite was not used and the amount of water used was 30 parts by weight.

The results are shown in Table 3.

Table 2 Table 3 Chemical composition of sodium metasilicate (%) Example 2 100 parts by weight of granulated blast furnace slag powder used in Example 1, 27.5 parts by weight of sodium metasilicate, and Seviolite 2
Regarding the binder made by mixing parts by weight, mortar mixed with 200 parts by weight of coal sand as a fine aggregate and 30 parts by weight of water was poured into a double formwork of 4 x 4 x] 6 cm to form a specimen. Created. The specimen is cured at a temperature of 2 until the third day of age.
Humid curing was carried out under conditions of 0°C and humidity of 95%, and then air-dry curing was carried out under conditions of temperature of 20°C and humidity of 60%. The specimen was demolded after one day of age, and then the specimen was sealed in a plastic bag and cured to a predetermined age.

The bending strength of the specimens that reached each material age was measured in accordance with JJS, R-5201. Table 4 shows the bending strength of the specimens of each material age.

Further, the length change was measured using the mortar. To measure the length change, place the mortar in a formwork for length change measurement (mortar bar method) and set the mortar at a temperature of 20°CyW and 95%.
The specimens obtained by moist curing under the following conditions and demolding at one day of age were air-dryed at a temperature of 20°C and humidity of 60%, and the length of the specimen at each age was measured. I went. Table 5 shows the shrinkage rate for each material based on the length at the time of demolding.

Comparative Example 2 The same procedure as Example 2 was carried out except that Seviolite was not used.

The results are shown in Tables 4 and 5.

Example 3 Curing after 3 days of age at a temperature of 20'C? The same procedure as in Example 2 was carried out except that sealing and curing were carried out under conditions of 95% W degree.

The results are shown in Table 4.

Comparative Example 3 The same procedure as Example 3 was carried out except that Seviolite was not used.

The results are shown in Table 4.

[Effects of the Invention] When the hydraulic binder of the present invention is used, unlike conventional alkali-activated slag cement, it is possible to obtain a mortar or concrete hardened product that has high initial strength and little decrease in long-term strength. Furthermore, mortar and concrete using the hydraulic binder of the present invention have little shrinkage during hardening.

Claims (1)

[Claims] (1) Add an alkali metal hydroxide, carbonate, or silicate to 100 parts by weight of pulverized blast furnace slag powder with a Blaine specific surface area of 3000 cm^2/g or more in an amount of 1 to 1 in terms of Na_2O.
A hydraulic binder characterized by containing 0.1 to 10% by weight of hydrated inosilicate of magnesium based on 0 parts by weight of activated alkali-activated slag.