JP5775655B2 - Concrete composition and method for producing the same - Google Patents

Description

  The present invention relates to a fine sand for concrete and a method for producing the same, in which fluidity and compressive strength do not decrease even when used as part of a concrete fine aggregate.

  In recent years, with the dryness of river sand, which is a good aggregate for concrete, a method for obtaining crushed sand for concrete by crushing mountain sand, sea sand, etc. using a crushed sand production apparatus has become common ( For example, Patent Document 1). However, in the method using the crushed sand production apparatus, it is difficult to treat the muddy water containing fine crushed sand generated in the pulverization process, the soil is mixed, the viscosity is adjusted, and the process is performed such as backfilling in the raw crushed stone mining site. There was a need. As a method for not performing this backfilling treatment, a method is disclosed in which mud water containing finely pulverized sand is used as a raw material for plant growth material in the slope planting method (for example, Patent Document 2).

Japanese Patent Laid-Open No. 2-102748 JP 2006-132186 A

  However, in the method of using muddy water containing finely pulverized sand as a raw material for plant growth materials in the slope revegetation method, it is sufficient that the demand for slope revegetation construction matches the amount of muddy water generated, but there are many cases where they do not match. The muddy water that cannot be treated will eventually be backfilled. Then, this invention aims at providing the concrete composition which dries muddy water containing finely pulverized sand, and uses it effectively as a fine aggregate for concrete, and its manufacturing method, when the method using a crushed sand manufacturing apparatus is used. To do.

  As a result of intensive studies to solve the above problems, the present inventors have adjusted the characteristics such as the average particle size and particle size distribution of finely pulverized sand, which is difficult to treat, and use it as a part of fine aggregate for concrete. As a result, the inventors have found that the above-mentioned problems can be solved, and have completed the present invention.

That is, the present invention is a concrete composition containing cement, coarse aggregate, fine aggregate, admixture, and water, wherein fine sand for concrete having an average particle size of 30 to 80 μm in the fine aggregate. It is related with the concrete composition containing 0 mass% or more.
The present invention also includes a step of supplying raw material sand and water to a cylindrical drum containing a pulverizing medium, rotating the cylindrical drum to pulverize and polish the raw material sand to obtain crushed sand, and classifying the crushed sand. And collecting the classified fine powder to obtain the fine powder sand for concrete, and mixing the obtained fine powder sand for concrete with cement, coarse aggregate, fine aggregate, admixture and water, and the above concrete composition The manufacturing method of the concrete composition including the process of preparing a thing.

  The fine sand for concrete of the present invention is used as a part of fine aggregate for concrete by adjusting the particle size, particle size distribution and other characteristics of finely pulverized sand, which is difficult to treat, so that material separation does not occur and fluid It is possible to obtain a concrete having good properties, a moderate amount of bleeding and a bleeding rate, and no problem in terms of compressive strength.

  Hereinafter, preferred embodiments of a concrete composition and a method for producing the same according to the present invention will be described in detail.

<Fine sand for concrete>
The fine sand for concrete used as the fine aggregate of the concrete composition of the present invention can be used in the same application as that of limestone fine powder generally used for improving the fluidity and material separation resistance of concrete. Specifically, it is used as a part of fine aggregate.

  The fine particle sand for concrete has an average particle size of 30 to 80 μm, preferably 35 to 75 μm, more preferably 40 to 70 μm, and particularly preferably 45 to 55 μm. The particle size distribution width is 1 to 300 μm, preferably 5 to 250 μm, more preferably 10 to 200 μm. Within these ranges, material separation does not occur, fluidity is good, bleeding amount and bleeding rate are moderately small, and sufficient compressive strength can be obtained when used as fine sand for concrete.

  The n value of the fine sand for concrete is 2.0 to 5.0, preferably 2.5 to 4.5, more preferably 3.0 to 4.2, and particularly preferably 3.5 to 4.0. This n value is the n value in the Rosin-Rammler diagram described in “Powder Engineering Society, edited by Powder Engineering Handbook, First Edition, Nikkan Kogyo Shimbun, February 28, 1986, p7-11”. It is an index showing. Within these ranges, material separation does not occur, fluidity is good, bleeding amount and bleeding rate are small, and sufficient compressive strength is obtained when used as concrete fine sand.

The BET specific surface area of the fine powder sand for concrete is 3 to 9 m ² / g, preferably 4 to 8 m ² / g, more preferably 5 to 7 m ² / g.
The loose apparent density is 0.85 to 1.10 g / cm ³ , preferably 0.90 to 1.00 g / cm ³ m, and more preferably 0.92 to 0.98 g / cm ³ .
The degree of dispersion is 36.0 to 40.0%, preferably 36.5 to 39.0%, more preferably 36.8 to 38.0%.
The specific surface area of Blaine is 500 to 3000 cm ² / g, preferably 800 to 2000 cm ² / g, and more preferably 1000 to 1500 cm ² / g.
The density is 1.5 to 3.5 g / cm ³ , preferably 2.0 to 3.0 g / cm ³ , more preferably 2.5 to 2.8 g / cm ³ .
If the BET specific surface area, loose apparent density, dispersity, brane specific surface area, and density are within the above ranges, no material separation occurs, fluidity is good, bleeding amount and bleeding when used as concrete fine sand. The rate is also moderately low and sufficient compressive strength can be obtained.

<Method for producing fine sand for concrete>
Next, a preferred embodiment of the method for producing fine sand for concrete of the present invention will be described.
Crude sand, mountain sand, sea sand, river sand, etc. can be used as raw material sand for fine sand for concrete. These raw material sands are put into a cylindrical rotary pulverizer together with water. The inside of the rotary crusher is filled with a grinding medium, and iron balls, rocks, or cobbles can be used as the grinding media. In particular, when cobblestone is used, not only crushing but also polishing is performed, and it is possible to obtain fine sand having a narrow particle size distribution and a small BET specific surface area, which is suitable for producing the fine sand for concrete of the present invention. The raw material sand and water may be added by either a continuous system or a batch system, but a continuous system is preferred from the viewpoint of productivity.

  The ratio of the input amount of the raw material sand and water is 10 to 500 parts by weight, preferably 50 to 400 parts by weight, and more preferably 100 to 300 parts by weight with respect to 100 parts by weight of the raw material sand. Within these ranges, it is possible to obtain fine sand for concrete having an average particle system, BET specific surface area, loose apparent density, dispersity, and brain specific surface area within the range of the present invention.

  Fine sand that has been pulverized and polished by a rotary pulverizer is classified by a classifier or a sieve. Although classified into coarse powder and fine powder by classification, the coarse powder can be used as a general concrete fine aggregate. The particle size to be classified is 10 to 150 μm, preferably 20 to 100 μm, more preferably 30 to 80 μm. The fine powder is muddy water containing water and fine sand, and the concentration is 1 to 20% by mass, preferably 2 to 10% by mass, and more preferably 3 to 8% by mass. Within these ranges, the fine sand recovery rate is high, and it is possible to obtain fine sand for concrete having an average particle system, BET specific surface area, loose apparent density, and dispersity within the range of the present invention.

  The muddy water classified in the above process is dried with a drier or the sun, or simply drained into fine sand. The fine sand or muddy water is further classified as it is with a classifier or a sieve, and the fine powder is recovered. The particle size to be classified is 10 to 150 μm, preferably 20 to 100 μm, more preferably 30 to 80 μm. Further, this fine powder is classified with a classifier or a sieve, and fine powder with a specific range of particle size is collected, so that a fine particle sand with a single particle size is more preferable. The specific range of the particle size has a lower limit of 10 μm, preferably 15 μm, more preferably 30 μm, and an upper limit of 150 μm, preferably 130 μm, more preferably 80 μm. The particle size range does not need to be 100% by mass in these ranges, but may be about 90 to 80% by mass.

  The recovered fine sand may be used alone as fine sand for concrete, or may be partially replaced with fine sand produced by other methods. In that case, the average particle system of the present invention, BET specific surface area Therefore, it is necessary to adjust the loose apparent density, the degree of dispersion, and the range of the specific surface area of the brain.

<Concrete composition>
The concrete composition of the present invention contains the above-mentioned fine sand for concrete, cement, coarse aggregate, fine aggregate, admixture and water, and 4.0% by mass or more of fine powder sand for concrete in the fine aggregate, Preferably, it is 5.0% by mass or more, more preferably 6.0% by mass or more, particularly preferably 6.0 to 50% by mass, and most preferably 6.5 to 40% by mass. Within these ranges, the slump at the time of concrete kneading does not collapse, aggregate separation does not occur, fluidity is sufficient, bleeding amount and bleeding rate are moderately small, and sufficient strength can be secured.
As the coarse aggregate and the fine aggregate, those defined in JIS A 0203 “Concrete terms” can be used. The fine aggregate is JIS A 5308 “Ready mixed concrete” [Appendix 1 Aggregate for ready mixed concrete] such as increase in unit water volume, increase / decrease in bleeding amount, change in setting speed, increase in latency, decrease in strength, etc. For this reason, the fine particle amount of fine aggregate is specified to be 5.0% by mass or less when the particle size is 0.075 μm or less. However, in the present invention, as a part of the fine aggregate, by adding 3.0% by mass or more of the finely divided concrete sand for which the particle size is adjusted, fluidity is improved without causing a decrease in strength, and an appropriate amount of bleeding. This makes it possible to achieve aggregate separation prevention.
As the admixture, AE water reducing agents such as lignin sulfonic acid, naphthalene sulfonic acid, polycarboxylic acid and melamine sulfonic acid, and high performance AE water reducing agents can be used.

The W / C (water / cement) of the concrete composition is 50 to 70%, preferably 55 to 65%. The s / a (fine aggregate ratio) is 40 to 60%, preferably 45 to 55%.
Unit amount of the concrete composition, water 150~200kg / ^{m 3,} preferably 170~190kg / ^{m 3,} the cement 150~400kg / ^{m 3,} preferably 200~350kg / ^{m 3,} the fine aggregate 700 1000 kg / ^{m 3,} preferably 800~900kg / ^{m 3,} the coarse aggregate 800~1000kg / ^{m 3,} preferably a 850~950kg / ^{m 3,.} Unit amount of concrete for the fine sand contained in fine aggregate, 28 kg / ^{m 3} or more, preferably 35 kg / ^{m 3} or more, more preferably 42 kg / ^{m 3} or more, particularly preferably 42~500kg / ^{m 3,} most Preferably it is 45.5-400 kg / m < ³ >. The unit amount of the admixture is 0.5 to 5.0 kg / m ³ , preferably 1.0 to 4.0 kg / m ³ , particularly preferably 2.0 to 3.5 kg / m ^{3 based} on the solution. Within these ranges, the slump at the time of concrete kneading does not collapse, aggregate separation does not occur, fluidity is sufficient, bleeding amount and bleeding rate are moderately small, and sufficient compressive strength can be secured.

<Method for producing concrete composition>
The concrete composition of the present invention is produced by kneading the above materials in the above unit amount using a general mixer such as a biaxial forced mixer or a pan mixer. In order to put the materials into the mixer, the admixture is diluted in advance with water, cement, coarse aggregate, and fine aggregate are added and stirred until they are sufficiently mixed.

  EXAMPLES The present invention will be described in detail below using examples, but the present invention is not limited to these examples.

[1. Preparation of fine sand for concrete]
200 parts by mass of crushed sand with respect to 100 parts by mass of water are continuously put into a cylindrical rotary crusher filled with sand for crushing, wet pulverized, and roughly coarse at about 40 μm by a classifier. The powder and fine powder were classified so that they could be separated. The muddy water containing the classified fine powder was dried at 105 ± 5 ° C. for 24 hours, and passed through a 0.075 mm sieve to prepare fine sand for concrete.

[2. Evaluation of the physical properties]
Various physical properties of the fine sand for concrete were evaluated. Moreover, the limestone fine powder (made by Ube Material Co., Ltd.) often used for the fine powder for concrete as a comparison was also evaluated.
The apparent apparent density and degree of dispersion were measured by the Carr method described in “Hayakawa Sohachiro, edited by powder physical property measurement method, Asakura Shoten Co., Ltd., published in 1973, p110-117”. As a measuring device, a powder tester PT-E type manufactured by Hosokawa Micron Corporation was used.

  Density and Blaine specific surface area were measured according to JIS R 5201 “Cement physical test method”. In addition, the porosity when measuring the Blaine specific surface area is a value in which the change in the Blaine specific surface area is within 2% when the porosity is changed by 0.010 in the range of 0.400 to 0.700, S1 was set to 0.480, S2 was set to 0.530, and S3 was set to 0.550.

  The BET specific surface area was measured in accordance with JIS R 1626 “Measurement method of specific surface area by gas adsorption BET method of fine ceramic powder”. Specifically, BELSORPmini manufactured by Nippon Bell was used, nitrogen was used as the adsorption gas, and the BET equation was applied to the adsorption isotherm measured by the constant volume method, and measurement was performed by the multipoint method. Note that the pretreatment of the sample was heated to 200 ° C. in a nitrogen atmosphere.

  The average particle diameter is calculated by creating a particle diameter-integrated sieve mass% curve from the particle size distribution measured using a laser diffraction particle size distribution measuring device [manufactured by Seishin Enterprise, LMS-30 (Laser Micro Sizer)]. The particle diameter at which the integrated mass% is 50% was determined from the particle diameter-integrated mass% sieve curve. The sample dispersion solvent was ethanol, the sample dispersion time by ultrasonic before measurement was 60 seconds, the measurement time was 30 seconds, and the number of measurement repetitions was 2. The laser diffraction method used both Fraunhofer diffraction and Mie scattering. The light source was a semiconductor laser with a wavelength of 670 nm and an output of 2 mW. The relative refractive index (particle refractive index / solvent refractive index) was set to 1.330.

  The n value is the n value in the Rosen-Rammler diagram described in “Powder Engineering Association, Powder Engineering Handbook, First Edition, Nikkan Kogyo Shimbun, February 28, 1986, p7-11”, and the particle size distribution. It is an index showing. The measurement was performed in the same manner as the average particle size. The measurement result was a Rosin-Rammler diagram, and the n value that was the slope was obtained. In the Rosin-Rammler diagram, each measured value of the total particle size was obtained by the least square method. Various physical property evaluation results are shown in Table 1, and particle size distribution results are shown in Table 2, Table 3, FIG. 1 and FIG.

[2. Evaluation of fluidity]
(1) Materials used (a) Cement (C)
Normal Portland cement (b) Fine aggregate (S)
Density 2.64g / cm ³ , FM2.92, fine particle content 0.8%
(C) Coarse aggregate (G)
Crushed stone 2015 (density 2.66 g / cm ³ , FM6.98) and crushed stone 1505 (density 2.66 g / cm ³ , FM6.29) were mixed and prepared in equal amounts.
(D) Fine powder sand for concrete (e) Admixture AE water reducing agent (EX60 manufactured by Tupole, a complex of a modified lignin sulfonic acid compound and a polycarboxylic acid compound, solid content 18% by mass) was used.
(F) Water Tap water (2) Kneading Kneading was performed with a forced biaxial mixer with a concrete volume of about 25L. Coarse aggregate, fine aggregate, and cement were added and stirred for 10 seconds. Water previously dissolved in an admixture was added and then kneaded for 60 seconds.
(3) Mixing of concrete The mixing is shown in Table 4 and Table 5.

(4) Evaluation items and results (a) Slump and slump flow: Measured according to JIS A 1101 “Concrete slump test method”.
(B) Bleeding amount and bleeding rate: Measured according to JIS A 1123 “Concrete Bleeding Test Method”.
(C) Compressive strength: Measured according to JIS A 1108 “Method for testing compressive strength of concrete” and JIS A 1132 “How to make specimen for concrete strength test”. The specimens were demolded at a material age of 1 day, and were cured under standard water until the test material age (7 days, 28 days).
The evaluation results are shown in Table 5. As shown in Table 5, by containing 4.0% by mass or more of fine sand for concrete in the fine aggregate (Examples 1 to 3), a slump flow of 31.0 cm or more can be obtained, and the slump may collapse. It can be seen that a concrete having excellent fluidity, moderate bleeding amount and bleeding rate, and sufficient compressive strength was obtained. In particular, by containing 7.0% by mass or more of fine sand for concrete (Examples 2 and 3), a concrete in which no aggregate separation occurred was obtained.

It is a figure which shows the particle size distribution of the fine powder sand for concrete. It is a figure which shows the particle size distribution of a limestone fine powder.

Claims (7)

A concrete composition containing cement, coarse aggregate, fine aggregate, admixture and water, for concrete having an average particle size of 40 to 80 μm and an n value of 2.0 to 5.0 in the fine aggregate Containing 3.0 to 9.0% by weight of fine sand,
The unit amount of the concrete composition is as follows: water 150-200 kg / m ³ , cement 150-400 kg / m ³ , coarse aggregate 800-1000 kg / m ³ , fine aggregate 700-1000 kg / m ³ , admixture Is a concrete composition characterized by having a solution standard of 0.5 to 5.0 kg / m ³ and an s / a (fine aggregate ratio) of 40 to 60% . The concrete composition according to claim 1, wherein the BET specific surface area of the fine sand for concrete is 3 to 9 m ² / g. ^3. The concrete composition according to claim 1 , wherein the loose apparent density of the fine sand for concrete is 0.85 to 1.10 g / cm ³ . The concrete composition according to any one of claims 1 to 3, wherein the degree of dispersion of the fine sand for concrete is 36.0 to 40.0%. Concrete composition according to any one of claims 1 to 4 Blaine specific surface area of the concrete fines sand is characterized by a 500~3000cm ² / g. Supplying raw material sand and water to a cylindrical drum containing a pulverization medium, and rotating the cylindrical drum to pulverize and polish the raw material sand to obtain crushed sand;
Classifying the crushed sand, recovering the classified fine powder, and obtaining the fine powder sand for concrete;
A step of preparing the concrete composition according to any one of claims 1 to 5 by mixing the obtained fine sand for concrete with cement, coarse aggregate, fine aggregate, admixture and water. The manufacturing method of the concrete composition characterized by the above-mentioned. The method for producing a concrete composition according to claim 6, wherein the particle size to be classified is 10 to 150 μm.

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