JPH0365548A - Production of salt-resistant pole - Google Patents

Abstract

PURPOSE:To obtain poles suitable for laying at the coast, having excellent salt resistance by preparing concrete comprising each specific amount of a cement admixture having a specific composition consisting essentially of ultrafine powder of blast furnace slag and anhydrous gypsum of II type and water and subjecting to centrifugal molding. CONSTITUTION:A cement admixture consisting essentially of 100 pts.wt. ultrafine powder of blast furnace slag comprising >=60 % particles having <=12mu diameter and 10-750 pts.wt. anhydrous gypsum of II type is produced. Then concrete containing 4-35 pst.wt. of the cement admixture based on 100 pst.wt. cement in concrete and having 30-50% ratio of water and cement is produced. Then the concrete is subjected to centrifugal molding to give salt-resistant poles. Consequently, synergistic effects of ultrafine powder of blast furnace slag and anhydrous gypsum of II type and water are developed and salt resistance can be improved.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a method for manufacturing salt-resistant poles.

<Prior art and its problems> Conventionally, the concrete used when manufacturing balls is usually 600 to 650 kgf/crA in order to obtain the design strength of 500 kgf/cn+"
It is formulated to provide the strength of
Concrete with a unit cement mass of 400 kg/m3 or more and a water-cement ratio of about 35% is used.

However, if a ball made using such concrete is installed along the coast, it will erode and crumble in a few years due to wave spray, and the reinforcing bars will rust due to penetration of chlorine ions in seawater. However, there were problems with durability, such as cracks and red rust appearing.

On the other hand, conventionally, blast furnace slag has been widely used in cement as blast furnace slag cement, and is classified into type A, type B, and type 0 depending on the amount of blast furnace slag blended. That is, Type A has a mixed amount of blast furnace slag of 30% or less, Type B has a mixed amount of more than 30% and less than 60%, and Type 0 has a mixed amount of blast furnace slag of more than 60% and not more than 70%. In order to prevent alkali aggregate reaction, it is recommended that the amount of blast furnace slag mixed is 40% or more.

However, the particle size of blast furnace slag normally used for blast furnace cement is around 4.000cm2/g in Blaine value, and the amount of particles of 12μ or less is less than 50%, and such coarse blast furnace slag Even when used in combination with type II anhydrous gypsum, the ability to develop high strength of type II anhydrous gypsum was rather impaired, and no significant improvement effect was observed in salt tolerance.

As a result of intensive studies to solve the above-mentioned problems, the present inventors found that by using a specific blast furnace slag powder and type anhydrous gypsum in combination with concrete with a specific unit amount of cement,
The present invention was completed based on the knowledge that the salt tolerance was improved and the above-mentioned problems could be solved.

Means for Solving the Problems> That is, the present invention consists of 100 parts by weight of blast furnace slag powder containing 60% or more of particles of 12μ or less and
The method is characterized by centrifugally forming concrete containing 4 to 35 parts by weight of a cement admixture whose main component is 100 parts by weight of cement in the concrete, and a water-cement ratio of 30 to 50%. This is a method for manufacturing salt-resistant poles.

The present invention will be explained in detail below.

The blast furnace slag powder in the present invention is blast furnace slag containing 60% or more of particles with a size of 12 μ or less.

Blast furnace slag powder is a fine powder obtained by pulverizing or crushing and classifying molten slag, which is a by-product of a blast furnace, which is rapidly cooled and vitrified.Other powders that are normally used for blast furnace cement can also be used.

Basicity (CaO+A1zOt+l+gO)/5i, which is shown as expressing the degree of latent hydraulicity of blast furnace slag
In the present invention, Oz is preferably 1.4 or more, more preferably 1.7 or more.

Moreover, the vitrification rate of blast furnace slag powder is preferably 50% or more, more preferably 90% or more.

The particle size of the blast furnace slag powder is such that particles of 12 μm or less account for 60% or more, and preferably 80% or more. 6 particles less than 12μ
If it is less than 0%, even if it is used in combination with Type 2 anhydrous gypsum, a sufficient strength development effect cannot be obtained, and the effect of improving salt tolerance cannot be obtained.

The finer the particle size of blast furnace slag powder, the better.The smallest blast furnace slag powder obtained by industrially and economically pulverizing or pulverizing/classifying the particle size of the Song Dynasty is usually 10μ or less and has a D50. The value is about 3μ, and it is more preferable to use such ultrafine slag.

When such ultra-fine blast furnace slag powder is used in combination with type 1 anhydrous gypsum, the salt resistance is improved compared to when blast furnace slag powder alone or type 2 anhydrous gypsum is used alone.

The reason for such a synergistic effect is unknown, but
By pulverizing the blast furnace slag, the dissolution rate of the AI component present in large amounts in the blast furnace slag becomes faster, which balances the dissolution rate of the ■-type anhydrous gypsum and the aluminate phase of the ■-type anhydrous gypsum and cement. Through the reaction, ettringite (3CaO・AlzO: +
- Generate 3CaSO4-32LO) to fill the voids in concrete and make it dense. At the same time, type anhydrous gypsum increases the volume of AI components in blast furnace slag, makes blast furnace slag particles porous, increases the amount of hydration reaction in the entire blast furnace slag, and gradually penetrates deep into the blast furnace slag. The resulting chlorine ions are extracted from Friedel salt (3CaO-AlzO:+・CaC1z4011) from the AI component in blast furnace slag.
It is thought that by fixing the salt in the form of zO), the permeation of chlorine ions remains low and salt tolerance is improved.

The ■-type anhydrous gypsum in the present invention is one whose X-ray diffraction pattern shows the form of Tl-CaSO4, and in addition to those obtained by firing trihydric, hemihydrous, and ■-type anhydrous gypsum, it can also be obtained from the hydrofluoric acid manufacturing process. By-products and natural anhydrous ceracola can also be used. In addition, type 2 anhydrous gypsum is not limited to impurities that are naturally or industrially contained.

■The powder level of type anhydrous scorch is 2,500 in Blaine value.
cm2/g or more is preferable, 4,000 to 7.500c
m2/g is more preferred. Blaine value is 2.500cm
If it is less than 2/g, it is not preferable because it tends to remain unreacted even after steam curing, and this tends to react over a long period of time, resulting in a lack of stability of the cement body.

The amount of type (1) anhydrous granola to be used is 10 to 750 parts by weight per part of blast furnace slag (200 parts by weight).

The amount of the cement admixture of the present invention, which is mainly composed of blast furnace slag powder and type anhydrous gypsum, is 4 to 35 parts by weight per 100 parts by weight of cement in concrete. In particular, 2 parts of blast furnace slag powder is added to 100 parts by weight of cement.
It is more preferable to use an amount of ~20 parts by weight, and 2 to 15 parts by weight of type (1) anhydrous cypress.

If the blast furnace slag powder or Type II anhydrous gypsum is less than 2 parts by weight, the effect of improving strength development and durability will be small, and if the blast furnace slag powder exceeds 20 parts by weight or type II anhydrous gypsum is 15 parts by weight. If it exceeds this, there is a tendency that no improvement in salt tolerance can be expected. In particular, when blast furnace slag powder exceeds 20 parts by weight, portlandite (C
a (OH) 2) disappears and the alkalinity decreases, which is not preferable because there is a concern not only about neutralization but also about rusting of the PC@ rod in the ball.

A more preferable usage amount of blast furnace slag powder and Type 1 water gypsum is 5 to 5 parts of blast furnace slag powder per 100 parts by weight of cement.
The cement admixture is blended in an amount of 16 parts by weight, 3 to 10 parts by weight of Type 1 water gypsum, and 8 to 26 parts by weight per 100 parts by weight of cement.

The ratio of blast furnace slag powder to type 1 water gypsum used at this time is equivalent to 19 to 200 parts by weight of type 2 water gypsum to 100 parts by weight of blast furnace slag powder.

The cement used in the present invention is normal, early strength, super early strength,
These include various types of Portland cement such as moderate heat and white color. Further, blast furnace cement cannot be used because it has problems such as neutralization, oxidation, and discoloration, but silica cement and fly ash cement can be used. The greater the hydraulic coefficient of cement and the greater the powderiness, the better the salt resistance.

In the present invention, the water-cement ratio is 30-50%.

If it is less than 30%, the weather resistance will deteriorate and cracks will occur, and if it exceeds 50%, the designed strength and other performance of the ball will not be achieved and the salt resistance will tend to deteriorate significantly.

In addition, when manufacturing a cement molded body using the cement admixture described above, chemical admixtures such as water reducing agents, limes, alkali metal sulfates, accelerators, and retarders can be used in combination, if necessary. .

In particular, it is preferable to use a water reducing agent in combination, and among these water reducing agents, it is more preferable to use a high performance water reducing agent in combination.

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 reduced metals, high-molecular weight trigeninsulfonates, and polycarboxylate salts as their main ingredients. Examples include product name rFT-500J and Hozoris Bussan product name rNL-4000J.

The amount of high-performance water reducing agent used is not particularly limited, but it is 0.2 to 2 parts by weight per 100 parts by weight of cement in terms of solid content.
Parts by weight are preferred.

When manufacturing balls using blast furnace slag powder, type water gypsum, and a high-performance water reducing agent, the compaction of the concrete may become poor and a mushy sludge with a high solid content may be discharged. be. In this case, lime and/or
Alternatively, by using an alkali metal sulfate, it is possible to improve compactness, reduce solid content separation, increase the amount of water removed, and produce a ball that is denser and has higher salt resistance.

Here, limes include quicklime or slaked lime, and alkali metal sulfates include sodium, potassium, and lithium sulfates and bisulfates.

The amount of lime and alkali metal sulfate used is 10
The range is 0.01 to 1.0 parts by weight relative to 0 parts by weight.

It is preferable to use lime and alkali metal sulfate in combination, each in an amount of 0.05 to 0.00 parts per 100 parts by weight of cement.
It is more preferable to use 5 parts by weight. If the amount of lime and/or alkali metal sulfate is less than 0.01 part by weight, there is almost no effect when using it, and if it is used in excess of 1.0 part by weight, salt resistance tends to be impaired.

The cement admixture of the present invention is mixed with cement, sand, gravel, and an appropriate amount of water, and if necessary, a water reducing agent, etc., and mixed with mortar or concrete to produce balls. They may be mixed in advance with cement to form a cement composition, or a certain amount of each may be mixed separately into a mixer directly during kneading, or they may be dispersed in water and mixed in the form of a slurry.

There are no particular restrictions on the kneading method or the molding method, and methods that are normally used when manufacturing balls can be used.

In addition, atmospheric pressure steam curing of poles using the cement admixture of the present invention is carried out in the range of 40 to 100 °C, and 50 to 8 °C.
A range of 0°C is more preferred.

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

Example 1 Using the concrete mixture shown in Table 1, the amount of blast furnace slag powder used was varied as shown in Table 2, and the mixing ratio with type water Ceracola and the amount of cement admixture added to cement were determined. Concrete was made by changing the

The water-cement ratio is simply the ratio (wt%) of the amount of water used and the amount of cement, and blast furnace slag (W) and ■ type water Ceracola were replaced by sand and volume. In addition, if the slump was outside the target slump depending on the amount of cement admixture, the slump was adjusted to some extent by adjusting the amount of water.

The amounts of cement admixtures, water reducing agents, etc. of the present invention are all parts by weight relative to 100 parts by weight of cement.
After pre-curing for 4 hours, the temperature was raised to 65°C at a rate of 15°C/h, maintained at that temperature for 4 hours, and then subjected to normal pressure steam curing. Thereafter, it was allowed to cool naturally, and the next morning it was taken out from the steam curing tank and various tests were conducted. In addition, the compressive strength at 28 days of age was determined after curing at 20±3°C and R1!60±5%. The results are also listed in Table-2.

Materials used: Cement: Denki Kagaku Kogyo ■, ordinary Portland cement (specific gravity 3.16) Water: Groundwater Sand: Niigata Prefecture Himeyoto River sand (specific gravity 2.65) gravel
: Crushed stone (specific gravity 2.68) Blast furnace slag powder: Blast furnace slag cement slag (no Sansui Ceracola, 48% particles of 12μ or less) made by Steel Barment Co., Ltd. was processed using a vibration mill or a combination of a vibration mill and a classifier as follows. Specific gravity 2.95 α: 12μ or less 53%, D50 approximately 12μ or less β:
〃 60 〃 9μr:
// 80 6μδ:
〃 100 3μ■ type anhydrous sesoko:
Manufactured by Shin-Akita Kakai■, hydrofluoric acid generation by-product Cenkora, Blaine value 6
,000 cm2/g (l.

City 0.5), specific gravity 2.93 Water reducing agent: High performance water reducing agent, Denki Kagaku Kogyo ■Art product name rp
r-500J (Specific gravity 1.20) Main component naphthalene sulfonic acid formalin condensate Test method> (1) Measurement of slag particle size Laser diffraction powder particle size analyzer Granulometer Model 715 manufactured by Cirrus Co., Ltd. (Measurement range 0 to 192
u) was used and dispersed in ethanol.

(2) Measurement of Strength Test Compressive strength was determined using a vibrating cylindrical specimen measuring φ1010×20, and tensile strength was determined by splitting the cylindrical specimen measuring φ15×15 cm.

(3) Measurement of the amount of chlorine ion penetration A φ1010×20 cylindrical specimen was demolded after 1 day of age, and then 20'C±3, l? After curing for 28 days in a curing box controlled at H60% ± 5, the specimen was immersed in a 3% NaCl aqueous solution, and after 91 days, the central part of the specimen was
The pieces were cut into pieces with dimensions of m, dried at 300°C for 24 hours, and then ground, and the amount of chlorine permeation was measured by fluorescent X-ray analysis.

(4) Measurement of carbonation depth A cylindrical specimen of φ1010×20 was cured for 28 days in the same manner as in the measurement of the amount of chlorine ion penetration, and then R11100%.
After curing for one year in a curing box with a CO2 gas concentration of 18% by volume, phenolphthalene was applied to the circular cut surface at the center and the average carbonation depth was measured.

As is clear from Table 2, in the examples in which appropriate amounts of blast furnace slag powder and H-type water gypsum were used, the immersion of chlorine ions was significantly reduced, and the effect of improving salt resistance was recognized.

In addition, regarding the particle size of blast furnace slag, the effect of improving strength and durability becomes remarkable when the particle size of blast furnace slag is 60% or more of particles of 12 μ or less and the combination of type water slag, and the finer the particle size of blast furnace slag, the more I know it's good too.

On the other hand, outside the scope of the present invention, the effect of improving salt resistance is small, or even if there is an effect of salt resistance, there is a problem of neutralization.

Example 2 Using concrete mixes with varying water-cement ratios as shown in mix codes A to G in Table-1, experiment No. 2 in Table-2 was used.
Using concrete mixed with cement admixture No. 1-12, a specimen measuring φ10 x 20 cm was formed in the same manner as in Example 1, and the compressive strength and the amount of chlorine ion penetration were measured.

The results are shown in Table-3.

The specimens that were removed from the mold the next morning were cured outdoors, and cracks were observed after the material was 1 year old.

Table 3 As is clear from Table 3, when the water-cement ratio exceeds 50%, the strength development effect decreases, and the actual pole strength, taking into account the coefficient of variation and safety factor, is 600 to 650.
If the water-to-cement ratio is lower than 30%, the weather resistance will be poor and cracking will occur.

In addition, the salt resistance is best when the water-cement ratio is around 37%, and as the water-cement ratio becomes smaller than that, the strength increases, but the amount of chlorine ion penetration gradually increases. This is presumed to be because the reaction rate of blast furnace slag decreases as the water-cement ratio decreases.

It is easily inferred that the occurrence of cracks deteriorates the salt resistance.

Example 3 Using concrete with mix codes A-D in Table-1, Table-2
Experiment No. 1-12 cement l-admixture, and as an additive, quicklime (a) burned in a gas-fired lime furnace and crushed to 88μ or less, and the quicklime that was digested by adding water. Dried slaked lime (b), sodium sulfate (c), potassium sulfate (d), lithium sulfate (each a primary reagent)
e) and sodium bisulfate (f) to 00 parts by weight of Semesolo as shown in Table 4.
A centrifugal force molding specimen of X 30 cm was molded, and the amount of sludge generated, the amount of solid content after drying it, the slag thickness which is the thickness of the part of the inner surface of the centrifugal force molding specimen that did not tighten, and Example 1
The compressive strength was measured for one day after steam curing in the same manner as above.

Furthermore, the material was demolded after 1 day of age, and kept at 20±3°C and R for 28 days.
1 (60±5% of the specimen cured in a curing box, 3% Na
After 91 days, the central part of the specimen was immersed in C1 aqueous solution.
The material was cut into 0x5xQ, 5cm slices, dried at 300°C for 24 hours, and ground, and chloride ions were measured using fluorescent X-rays, and cracks at one year old due to outdoor exposure and curing were observed. The results are also listed in Table-4.

In addition, centrifugal force forming was performed for 2 minutes at 3G, 4 minutes at 9G, and 3 minutes at 30G, a fixed amount of 18 kg of concrete was poured, and the hollow part was covered to prevent the separated sludge from getting wet.

As can be seen from Table 4, when manufacturing salt-resistant poles using the cement admixture of the present invention, the use of lime and/or alkali metal sulfates improves the formability and improves salt-resistant poles. It has the effect of improving sex.

Example 4 Using the concrete mixture with the mixing number of Example 1, concrete with and without the cement admixture of experiment Nα1-12 in Table 2 was used, and the length was 13o+, the diameter was 1
An OA type ball with a diameter of 90 mm and a design crack load of 350 kJf was centrifugally formed. In the same manner as in Example 1, after steam curing, a bending strength test was conducted on the 28th day of age for the poles with A composition and on the 7th day of age for the poles with B composition, and the load up to the first crack and the breaking load ( The design value of 700 kgf) was measured.

Furthermore, the pole was cut approximately in the center to a width of 10 cm, and the end surface and inner surface were coated with epoxy resin.
After immersed in NaCl aqueous solution for 91 days, the center part was
．． The sample was sliced into 0 cm pieces, the entire amount was crushed, and the amount of chlorine ion permeation was measured by fluorescent X-ray analysis. Furthermore, the rusting status of the reinforcing bars was also confirmed.

The reinforcing bars are made of high-frequency hot wire, and the reinforcing bars are made of tension PC.
Steel rods φ7.4numXB and reinforcing steel rods φ7.4mmX4
For the main (straight bar) and spiral bar, iron wires with a diameter of 3 mm were arranged at 10 cm intervals, and the initial jtJJ tension stress of the PC steel bar was 10.150 kgf/c-. The results are shown in Table-5.

Table 5 <Effects of the Invention> As shown in the examples, by using the method for manufacturing a salt-resistant ball of the present invention, a pole with high salt resistance can be manufactured.

Claims (1)

[Claims] (1) Blast furnace slag powder 1 with 60% or more particles of 12μ or less
Contains 4 to 35 parts by weight of a cement admixture containing 10 to 750 parts by weight of Type II anhydrous gypsum and 10 to 750 parts by weight of Type II anhydrous gypsum, with a water-cement ratio of 30 to 50%. A method for manufacturing a salt-resistant pole, characterized by centrifugally forming concrete.