JP4220930B2 - Concrete for manufacturing centrifugal force molded body, centrifugal force molded body using the same, and method for manufacturing the same - Google Patents

Description

The present invention relates to a concrete for producing a centrifugal force molded body, a centrifugal force molded body using the same, and a method for producing the same, and more specifically, a concrete pile, a pole, a steel pipe composite pile produced by centrifugally molding mortar or concrete, The present invention relates to a steel tube lining and a concrete for producing a centrifugal force formed body that reduces the occurrence of noro during the production of concrete products such as a fume tube, a centrifugal force formed body using the same, and a method for producing the same.

Conventionally, at the time of manufacture of concrete products manufactured by centrifugal force forming such pile or pole, slag is squeezed out by centrifugal force, it comes to occur.
This NORO is a strong alkaline sludge containing 20 to 40% by weight of fine particles such as cement and sand, so it cannot be disposed of outside the factory as it is to prevent pollution. , supernatant is drained and neutralized, precipitate, you are dumped as industrial waste. It is that are over a lot of time and money status quo for the sake of it.
The slag in order to reduce the occurrence of, the present inventor has proposed a method for producing a slag-reducing agent as a main component of bentonite and centrifugal force molded article using it (see Patent Document 1).

However, this known Noro reducing material, Ru der only mentions the degree of swelling and Noro reduction effect of bentonite. Rise Jund only the magnitude and amount of the unit cement content in the concrete is extremely small, and, if and, turned methods pump beating to mold using water retention small aggregate such as crushed sand For example, when the concrete slump is large, there is a problem that the practical use range is narrow due to variations in the reduction effect.

Japanese Patent Laid-Open No. 03-247543

  As a result of diligent research for the purpose of solving the above-described problems and further improving the reduction effect, the inventors have found that the reduction effect can be effectively enhanced by using bentonite having a specific swelling degree and a specific particle size. As a result, the present invention has been completed.

That is, the present invention contains cement, a bentonite having a degree of swelling by ACC method of more than 22 to 80, and a maximum secondary particle size of 63 μm or less, and a high-performance water reducing agent. Is 0.2 to 15 kg / m ³ , and the high-performance water reducing agent is 0.05 to 1.5 parts by weight in terms of solid content with respect to 100 parts by weight of cement. a centrifugal force molded article made Te, the concrete molded centrifugal force, a method of manufacturing the steam curing and / or autoclave curing to name Ru centrifugal molding.

  Hereinafter, the present invention will be described in detail.

The bentonite used in the present invention is a kind of clay mineral mainly composed of montmorillonite and has swelling properties.
Swellable bentonite depends origin and deposits, and artificial purification and synthesis, by chemical treatment or the like, it is possible to increase the degree of swelling, viewpoint et Noro reducing effect, large Rise Jund it is not preferable. In the present invention, those having a degree of swelling by ACC method (American Colloid Campany standard) of more than 22 to 80 are used , preferably 25 or more , more preferably 30 to 50. If the degree of swelling exceeds 80 , the unit water amount becomes too large and the strength decreases, which is not preferable.
The degree of swelling by the ACC method in the present invention was determined by the following method.
That is, 2.0 g of a sample is added to a 100 ml graduated cylinder containing 100 ml of purified water in about 10 times, and then stoppered.
However, the amount added once is adjusted so that the sample added earlier does not adhere to the inner wall and deposits smoothly on the bottom of the cylinder, and the next sample is added after the sample added earlier has almost deposited. . The sample is allowed to stand for 24 hours after the addition, and the apparent volume (ml) of the sample deposited in the container is read, and this value is taken as the degree of swelling (ml / 2g) by the ACC method in the present invention.

Furthermore, the bentonite used in the present invention is a particle having a maximum secondary particle size of 63 μm or less. As a method of maximum secondary particle diameter is prepared following bentonite 63 .mu.m, but are not limited to, For example, there is a method of classifying after the grinding or milling the base bentonite.
From the viewpoint of enhancing the reduction effect, the present inventor screened by the dry sieving method and examined the particle size of each secondary particle. As a result, depending on the particle size, the swelling property, the unit water volume of concrete, slump, etc. Despite the fact that there is no difference at all, it has been observed that the effect of reducing lozenge changes drastically at the maximum secondary particle diameter of 63 μm, and that the effect of reducing drastically is enhanced below 63 μm.

To clarify the reason, 2% bentonite was added to the cement, and the cement paste was kneaded. Immediately thereafter, the fracture surface was observed with a scanning electron microscope while being frozen with liquid nitrogen . As a result, it is inferred that the card house structure by bentonite sheet-like crystals is formed on the cement particles or between the particles, and the small honeycomb-like blocks are in a dense state. It is thought that the water in the concrete is confined in this block and is prevented from moving by centrifugal force, and as a result, the effect of reducing the particle size can be obtained, but the maximum secondary particle diameter is 63 μm or less. In some cases, when kneaded with concrete, it is assumed that the card house structure as described above is formed at a high speed in the concrete.

The amount of bentonite in the invention, and a small amount the greater the degree of swelling of the bentonite exert slag reduction effect, furthermore, than added in powder form, the water, or water and superplasticizer like better to use together in the slurry is, it exert a more Noro reduction effect. Normally, in the concrete 1 m ^3, a bentonite 0.2 to 15 kg, the 0.5~10kg is considering the securing and economics of good preferred, Noro reduction effect and strength, 1.0～8Kg is more preferable. In concrete 1 m ^3, by using the bentonite beyond 15 kg, a tendency that strength reduction in the unit amount of water even with a small degree of swelling is too large increases. Also, if the amount of the high-performance water reducing agent is increased so as not to lower the strength and the water cement ratio is lowered, the viscosity inherent to the high-performance water reducing agent appears in the concrete itself, and the effect of reducing the loss is reduced. On the other hand, if the amount is less than 0.2 kg, the degree of swelling is large, and even if it is used in a slurry, the effect of reducing the roll cannot be obtained so much.

The centrifugal molded body of the present invention has a unit cement amount of 350 to 600 kg / m ³ , a water cement ratio of 25 to 36%, and a high-performance water reducing agent in terms of solid content with respect to 100 parts by weight of cement in concrete. in 0.05 to 1.5 parts by weight, and bentonite 0.2~15kg / m ³ formulated to kneading the concrete, the slump and 0～18Cm, poured into a mold by Incorporating how expression or pumps pumping scheme, after centrifugal molding Obtained by steam curing and / or autoclave curing.

  From the viewpoint of strengthening the water retention capacity, the amount of unit cement has an effect on the reduction effect, and if the other conditions are the same, the larger the amount of cement, the smaller the water cement ratio can be. Also has a good impact.

Therefore, the unit cement amount, water cement ratio, high-performance water reducing agent usage amount, and bentonite amount are organically linked and cannot be limited independently, to ensure the in amount bentonite 0.2 to 15 kg / m ^3, the unit amount of cement is required 350~600kg / m ^3, preferably 380 ~550kg / m ^3. If the unit cement amount is less than 350 kg / m ³ , the water retention will be reduced, and the effect of reducing spatter will be hindered. If it exceeds 600 kg / m ³ , it will be uneconomical, and the paste layer on the inner surface of piles after centrifugal molding Becomes too thick, and it tends to drop off due to impact during movement, etc., which is not preferable.

As the cement used in the present invention, various portland cements such as normal, early strength, ultra-early strength, and moderate heat, various mixed cements blended with these portland cements, blast furnace slag, fly ash, or silica, and Examples include slag-based cement in which fine slag is blended to JIS standards or higher , and alumina cement used in steel pipe lining.

The concrete slump is preferably 0 to 18 cm. The softness of slump is more than 18cm, even to reduce the generation of slag, too soft paste layer of the inner surface, such as pile, undesirably liable to fall off due to an impact or the like during movement, as slump opposite small Noro effect of reducing Ru be exhibited. Nevertheless, in a state that does not clog well slump cone be the same slump 0, since the Janka easily occurs in the end portion of the centrifugal force formed body, and more preferred slump is 1.0～15Cm.

The water-cement ratio of the concrete used in the present invention is preferably 25 to 36%. If the water-cement ratio exceeds 36%, the concrete for producing centrifugal force-formed bodies using the bentonite has a small amount of dewatering due to centrifugal force forming, and the water-cement ratio of the centrifugal force-formed body does not decrease. Ri is difficult der to secure a 500 kgf / cm ² is the design strength of the PC pile JIS be produced by curing, even when autoclave curing is a P HC pile, or using a high strength admixture for steam curing Even with steam curing, it is difficult to ensure a design strength of 800 kgf / cm ² . Further, in order to obtain a concrete of less than 25%, it is necessary to increase the unit Semen'nto amount, in this case too thick thickness of the paste layer of the inner surface, such as pile after centrifugal molding also impact during movement It is not preferable because it is easy to fall off. More preferably, it is 26 to 34%.

A high-performance water reducing agent is necessary from the viewpoints of promoting strength and ensuring the strength of the water-cement ratio of 25 to 36%.
A high-performance water reducing agent is a water-reducing agent having a higher water reduction rate than conventional lignin sulfonate-based water reducing agents, and the commercially available high-performance water reducing agent is a polyalkylallyl sulfonate-based high - performance water reducing agent. , Melamine formalin sulfonate-based high - performance water reducing agent , aromatic amino sulfonate-based high - performance water reducing agent , and polycarboxylic salt-based high - performance water reducing agent as the main component, and there is a mixed type of these .

The polyalkylarylsulfonic acid salt-based high performance water-reducing agent, methyl naphthalene sulfonate formalin condensates, naphthalenesulfonic acid formalin condensate, and include anthracene sulfonic acid formaldehyde condensate, as its commercially available product, manufactured by Kao Corporation Sanyo Kokusaku Pulp, including the product names “Mighty 100”, “Mighty 150”, “Mighty 2000” series, etc., Daiichi Kogyo Seiyaku brand name “Cellflow 110P”, Takemoto Yushi Co., Ltd. product name “Pole Fine 510N” Typical product names such as “Sunflow PS” and “Sunflow HS700” manufactured by the company, and “FT-500” manufactured by Denki Kagaku Kogyo Co., Ltd. Examples of the agent are trade names “Melment F-10” and “Melment F-20” manufactured by Showa Denko KK, such as “FT-3S” manufactured by Denka Grace. And examples of the aromatic aminosulfonic acid salt-based superplasticizers like Fujisawa Co. trade name "Subotica 200" series.

Further, in the polycarboxylate-based high - performance water reducing agent , an olefin-maleic acid copolymer system, an alkenyl ether-maleic anhydride copolymer system, an acrylate-acrylic acid ester copolymer system (including a carboxy group, and And sulfonic acid group-containing multi-component polymers and polyether carboxylate-based polymers), and those obtained by adding a hydrolyzable polycarboxylic acid crosslinked product to improve slump retention.

  Examples of these commercially available products include series such as “Darex Super 200” manufactured by Denka Grace, “Tupol HP11” manufactured by Takemoto Yushi Co., Ltd., and “Reobuild SP-8HS” manufactured by Pozoris Bussan.

The amount of the high-performance water reducing agent used is 0.05 to 1.5 parts by weight in terms of solid content with respect to 100 parts by weight of cement.
Increasing the amount of use of the high-performance water reducing agent increases the water reduction and decreases the water cement ratio, so that the strength increases. However, an appropriate amount is also shown from the viewpoint of preventing noro . If added in excess of the appropriate amount, no reduction effect is exhibited. The upper limit of the appropriate amount varies depending on the amount of bentonite used and the method of adding a high-performance water reducing agent (simultaneous addition, post-addition, etc.). Polycarboxylate-based high-performance water-reducing agent increases the water-reduction rate in a smaller amount than other high-performance water-reducing agents. However, increasing the amount used increases the retardation and causes a decrease in strength. The amount of the salt-based high-performance water reducing agent used is 0.05 to 0.5 parts by weight in terms of solid content with respect to 100 parts by weight of cement, and the other high-performance water reducing agent is 0.3 to 1.5 parts by weight . If it is less than 0.05 parts by weight, the water-reducing effect is small even with polycarboxylate-based high - performance water reducing agents , and even if other high-performance water reducing agents are added in excess of 1.5 parts by weight, the water-reducing rate does not increase and viscosity tends to appear. Even if the addition amount of bentonite is increased, the effect of reducing rotting is inhibited, which is not preferable. More preferably, it is 0.1 to 0.3 parts by weight for polycarboxylate-based high-performance water reducing agents , and 0.4 to 1.2 parts by weight for other high-performance water reducing agents.

Steam curing or autoclaving nourishing production that put the present invention may in a conventional manner, which is not particularly limited, to ensure strength in steam curing, use of such a high-strength admixture preferably, specifically Is commercially available with gypsum as the main component. Moreover, in order to raise the adhesive force with a steel pipe, use of a cement expansion material etc. is also preferable. Since these cement admixtures are finely powdered or have high hydration activity, they increase water retention and promote the anti-snoring effect.

Further, the bentonite of the present invention is added when kneading mortar or concrete, and the kneading method may be a commonly used method. The method for adding bentonite according to the present invention is not particularly limited. Therefore, it may be added together when mixing kneading concrete as a powder, or may be to put the slurry suspended in a portion or all of the kneading water, further, superplasticizer It may be added after being suspended in a part or all of the kneaded water. In more turning flour powder state, better to put in suspension to the slurry is particularly preferred slurry added so Noro preventing effect is exhibited by the smaller amount. The timing of inputs, in the kneading method for post-added superplasticizer, better to put the slurry in suspension with a portion of the kneading water after the addition of superplasticizer is, Mixing time is short preferably since Noro preventing effect is larger, in the kneading method of adding simultaneously with water kneading a superplasticizer together and suspended in a kneading water and superplasticizer other concrete material It is preferable to put in

Centrifugal force forming method of the present invention, low speed, medium speed (medium speed I, medium speed II), and a conventional method performed in 3-4 stages using a high-speed are used, in particular, have name to be limited. Since the concrete to which bentonite of the present invention is added becomes a plastic, in order to improve the extension in the axial direction, especially in the case of a low slump such as a built-in type , the low speed GNo. 0.5-2G is more preferable. The low-speed rotation time is preferably 0.5 min or more, more preferably 1 min or more, and most preferably 2 to 6 min. Medium speed I includes medium speed I and medium speed II, and when the total speed is 4 stages, medium speed I is 0.5 min or more at about 4-8G in order to make the thickness of the centrifugal molded body uniform. In addition, as medium speed II, in order to arrange the aggregate in the circumferential direction and prepare for the transition to high speed, if the slump is as low as 5cm or less, it is 12-20G, and the slump exceeds 5cm When pumping, it is preferably performed at 8 to 15 G and 0.5 min or more, more preferably 1 min or more and 2 to 5 min. The high speed does not require any particular regulation or unification of the GNo. And rotation time, it is tight and there is no occurrence of slack, and it does not have to drop off due to impact during transportation. high or slump was used small small unit cement content be crushed sand or the like, in the case of easy concrete tight water-holding capacity is small, the rotation time of about 20G is sometimes good for about 1min. Further, on the contrary, water holding capacity and many units cement weight strongly, slump is small, such as a large diameter pile, it may be difficult interference may also at about 30G required over 20min.

1. Of the present invention, a degree of swelling 22 super 80, by using the 0.2~15kg / m ³ centrifugal molding producing concrete used in the unit volume and the maximum secondary particle diameter is less base bentonite 63 .mu.m, The reduction effect at the time of manufacturing a centrifugal force molded body can be enhanced.
2. By limiting the concrete blending and the like, it is possible to achieve a reduction in strength and securing of strength, and it is possible to manufacture piles having excellent bending strength as well as compressive strength.
3. By producing a centrifugally molded product with concrete for producing a centrifugally molded body using the bentonite of the present invention, it is possible to reduce the amount of noro currently disposed of as industrial waste. Useful for environmental conservation.

EXAMPLES Hereinafter, although this invention is demonstrated concretely by an experiment example , this invention is not limited to these experiment examples .

Experimental example 1
Bentonite having different degrees of swelling was sieved with a dry sieve to prepare bentonites having a particle size range. Based on the concrete mix in Table 1, crushed sand, crushed stone, and cement + bentonite (that is, bentonite was added in this case as powder and simply replaced with sand by weight) was put into a planetary 100 liter mixer Then, after stirring for 20 seconds dry, an aqueous solution in which the high-performance water reducing agent A was dissolved was added to the kneaded water, and kneaded for 90 seconds to prepare 40 liters of concrete, and the slump was measured.
The produced concrete is put into a fixed amount of 18Kg and subjected to centrifugal molding under the conditions of 2G x 3min, low speed 4G x 1min, medium speed II 10G x 3min, high speed 30G x 5min, and outer diameter. A centrifugal force molded specimen 20 × length 30 × thickness 5 cm was prepared, and the amount of noro generated at this time was measured.
At this time, the hollow opening portions at both ends of the mold were covered so as to prevent leakage of the generated slot, and centrifugal force molding was performed. In addition, the molded specimen was heated up to 80 ° C. at a heating rate of 20 ° C./hrs after 2 hours, held for 4 hours, steam cured , allowed to cool to the next day, and then demolded. It was cured indoors at a temperature of 20 ° C. ± 3 ° C., and the compressive strength at the age of 28 days was measured. The results are shown in Table 2. The slump value was adjusted by adding the high-performance water reducing agent while keeping the water cement ratio constant.

<Materials used>
Cement: Electrochemical Industry Co., Ltd., ordinary Portland cement crushed sand: Himekawa, Niigata, crushed sand, specific gravity 2.64
Crushed stone: Himekawa, Niigata prefecture, crushed stone, specific gravity 2.64
High-performance water reducing agent A: trade name “Cell Flow 110P” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., main component polyalkylallyl sulfonate-based high - performance water reducing agent , powder bentonite a: degree of swelling 22 (ACC method) natural Product bentonite b: degree of swelling 25 (A.C.C. method) natural product bentonite c: degree of swelling 30 (A.C.C. method) natural product bentonite d: degree of swelling 45 (A.C.C. method) Purified bentonite e: Swelling degree 80 (AC method) Chemically modified with alkyltrialkoxysilane Bentonite: 150 μm fine bentonite when sieved with 150, 90, 63, and 44 μm sieves: 150-90 μm bentonite when sieved with 150, 90, 63, and 44 μm sieves: 150-90 μm bentonite when sieved with 150, 90, 63, and 44 μm sieves: 150, 90, 63-44 μm when sieved with 63 and 44 μm sieves Bentonite Ho: 150,90,63, and 44μm under article when sieved by a sieve of 44μm

<Measurement method>
Slump: Conforms to JIS A1101 Noro amount: Measured using a graduated cylinder Compressive strength: Conforms to JIS A1108

From Table 2, it can be seen that when the swelling degree of bentonite exceeds 22, regardless of the amount of addition, the reduction effect is different when the maximum secondary particle diameter is above and below 63μm, and the remarkable reduction effect is shown below 63μm. I understand.

Experimental example 2
Using the basic formulation of the concrete in Table 1, sieve base bentonite c at 63 .mu.m, changing the amount added with the bentonite under 63 .mu.m, was subjected to the same tests as in Experimental Example 1. The results are shown in Table 3.
The high-performance water reducing agent used was that used in Experimental Example 1 and the high-performance water reducing agent B was partially used. In addition, in order to match the slump, a test was performed when the water cement ratio was constant and the addition amount of the high-performance water reducing agent was changed, and when the addition amount of bentonite was constant and the slump was partially adjusted with the unit water amount. It was .

<Materials used>
High-performance water reducing agent B: Product name “Darlex Super 200” manufactured by Denka Grace Co., Ltd., polycarboxylate-based high - performance water reducing agent , solidified lump

From Table 3 the water-cement ratio is constant, increasing the amount of bentonite under 63μm amount of superplasticizer is increased, even with the addition of bentonite 15 kg / m ³ or more, superplasticizer amount When the amount exceeds 1.5 parts by weight, the effect of reducing the loss is lost, and the amount of the high-performance water reducing agent is 1.5 parts by weight or less, preferably 1.2 parts by weight or less.
In addition, if the amount of high-performance water reducing agent is reduced, the reduction effect will not become extremely small, but if the rate of unit water increase to obtain the same slump is large and the water cement ratio exceeds 36%, 500 kgf / It tends to be difficult to ensure design strength such as piles of cm ² , and polycarboxylate-based high - performance water reducing agents have a large water-reducing effect, but if added in an amount exceeding 0.5 parts by weight, they are delayed. Tends to increase and it becomes difficult to ensure the strength.

Experimental example 3
For Experiment Nos. 2-5 to 2-8 in Experimental Example 2, the whole amount of the kneaded water, the high-performance water reducing agent, and bentonite were suspended and added to the slurry, and the same test as in Experimental Example 1 was performed. The results are shown in Table 4.

  From Table 4, it is remarkably shown that when added as a slurry, the effect of reducing the roughness is amplified and the strength is easily obtained.

Experimental Example 4
Tests similar to those in Experimental Example 1 were performed using concrete blends with different unit cement amounts and water cement ratios in Table 5.
Bentonite, use those under 63μm in Baie bentonite c, superplasticizer were the same as in Experimental Example 1. Moreover, the measurement of the thickness of the paste layer on the inner surface was added to the test item.
Moreover, the concrete which changed the slump arbitrarily was also used for the concrete of a part mixing | blending, increasing / decreasing a unit water amount. Test results are shown in Tables 6-7.

< Measurement method >
Paste thickness: After molding, insert monosashi into the paste layer and measure the thickness of the paste layer

Experimental Example 5
Using the concrete composition shown in Table 8, 0.7 m ³ concrete was mixed for 90 seconds with a 1 m ³ bread mixer.
Bentonite, it was used under 63μm in Baie bentonite c. Bentonite was added as a slurry mixed with the total amount of kneaded water.
Further, a high-performance water reducing agent C and a high-strength admixture for steam curing were used. Centrifugal molding conditions, using a kneading concrete, low speed 1.5G × 4 minutes, medium speed I is 4G × 1 minute, medium speed II is 15G × 3 minutes, fast as 25G × 3 min, the outer diameter Two types of A-type single piles with an effective prestress of 40 kgf / cm ² of 300 mm × length 1 m × thickness 60 mm, outer diameter 300 mm × length 3 m × thickness 60 mm were manufactured.
In addition, the specifications of the pile were 6 PC steel bars with an outer diameter of 8mm, and the helical bars had an interval of 50mm between ordinary steel wires with an outer diameter of 5mm.
Moreover, concrete Incorporating in Incorporating manner, blank comparison was 5 volume% more concrete input amount in anticipation of the amount of slag is generated.
Steam curing conditions are as follows: after forming by centrifugal force, pre-curing for 2 hours, increasing to 75 ° C. at a rate of 20 ° C./hr, holding for 4 hours, and then allowing to cool naturally in the curing layer until the next day for demolding Then, the compressive strength of a single pile having an outer diameter of 300 mm × length of 1 m × 60 mm and the static bending strength of a single pile having an outer diameter of 300 mm × length of 3 m × thickness of 60 mm when measured for one week outdoors were measured. The results are shown in Table 9.

<Materials used>
Cement: Electrochemical industry, ordinary Portland cement sand: Shogawa, Toyama Prefecture, sand, specific gravity 2.66
Crushed stone: Shokawa, Toyama Prefecture, crushed stone, specific gravity 2.66
High-performance water-reducing agent C: trade name “FT-500” manufactured by Denki Kagaku Kogyo Co., Ltd., liquid polyalkylallylsulfonate-based high - performance water-reducing agent with a solid content of 43% <br/> High-strength admixture: Electrochemical Industry Product name "Denka Σ1000"

<Measurement conditions>
Static bending strength: Conforms to JIS A5337

In the examples of the present invention, there was no occurrence of noro, and in the comparative pile, 48 l / m ³ of noro was generated. As a result, the thickness of the pile was almost the same.

Claims (3)

Containing a cement, bentonite with a maximum secondary particle size of 63 μm or less and a high-performance water reducing agent with a degree of swelling by ACC method of more than 22 to 80, and the unit amount of bentonite is 0.2 to 15 kg / m ^{3. A} concrete for producing centrifugally molded products, wherein the high-performance water reducing agent is 0.05 to 1.5 parts by weight in terms of solid content with respect to 100 parts by weight of cement. A centrifugal force-molded body obtained by centrifugally molding the concrete for producing a centrifugal force-molded body according to claim 1 . Method for producing a centrifugal force molding producing concrete molded centrifugal force, steam curing and / or autoclave curing to centrifugal force molded body formed of claim 1.