JP5169368B2 - Self-healing hydrated cured product and low-reactivity active cement material - Google Patents

Self-healing hydrated cured product and low-reactivity active cement material Download PDF

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JP5169368B2
JP5169368B2 JP2008078649A JP2008078649A JP5169368B2 JP 5169368 B2 JP5169368 B2 JP 5169368B2 JP 2008078649 A JP2008078649 A JP 2008078649A JP 2008078649 A JP2008078649 A JP 2008078649A JP 5169368 B2 JP5169368 B2 JP 5169368B2
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water
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JP2009227557A (en
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裕一 小田部
修輔 原田
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住友大阪セメント株式会社
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Description

  The present invention relates to a self-healing hydrated hardened material and a low-reactivity active cement material that actively repair cracks in order to ensure long-term durability of a mortar or concrete structure.
Hydrated cured products such as mortar and concrete have a high resistance to compression but a low resistance to tension. Therefore, cracking occurs when tensile stress acts on the hydrated cured product or when volume changes due to temperature change or drying. There is a drawback that it is easy. When cracks occur in a reinforced concrete structure, not only the appearance is impaired, but carbon dioxide and rainwater in the atmosphere penetrate into the concrete from the cracked surface, corrode the embedded reinforcing steel, and cause structural defects. obtain. For this reason, repairs such as waterproofing and waterproofing have been carried out for excessive cracking.
However, such crack repair has a problem that it costs much higher than the unit cost of concrete and increases the maintenance cost of the reinforced concrete structure.
  As a means for solving such a problem, Patent Document 1 discloses a self-repairing hydrated cured product containing an unhydrated cement clinker as an aggregate. Further, Patent Document 2 discloses a concrete configured such that an unreacted portion of a powder containing cement remains at the time when it is hardened after placing, and concrete means includes cement for water. Increasing the amount is disclosed.
JP-A-9-86983 JP 2003-267765 A
However, in the method of blending cement clinker with the above-mentioned hydrated cured product, the gypsum component is insufficient, and there is a risk of rapid or instantaneous setting, or the fluidity of the resulting hydrated cured product may be adversely affected. Furthermore, if the particle size of the cement clinker to be blended is too large, there is a possibility that locally generated cracks cannot be repaired.If the particle size is too small, the reactivity is too high. It is almost complete and the cement clinker may not be able to contribute to crack repair. Moreover, in the method of increasing the amount of cement with respect to water, the self-healing ability of the obtained hydrated cured product was insufficient.
An object of this invention is to provide the self-healing hydrated hardened | cured material and low-reactivity active cement material which have the outstanding self-healing capability in such a condition.
The present inventors have made intensive studies in order to achieve the object, the low reaction activity cement materials obtained by containing less water theoretical amount of water required for the hydration of the raw cement raw cement The present inventors have found that the object can be achieved more and have completed the present invention based on this finding.
That is, the present invention
1. Secondary particulate low-reactivity cement obtained by adding 5 to 25 parts by mass of water to 100 parts by mass of the raw material cement and mixing with a mixer and then holding for 3 days or more material,
2. 2. The low-reactive activity cement material according to 1 above, wherein the average particle size is 20 to 70 μm ,
3. The low-reactivity active cement material according to the above 1 or 2 , which is used for adding a hydrated cured product,
Is to provide.
  ADVANTAGE OF THE INVENTION According to this invention, the low reaction activity cement material which provides the self-healing capability to the self-healing hydrated hardened | cured material which has the outstanding self-healing capability, and a hydrated hardened | cured material can be provided.
The self-healing hydrated and cured product of the present invention contains cement, water, and a low-reactivity active cement material obtained by causing the raw cement to contain less than the theoretical amount of water necessary for hydration of the raw cement. .
The present invention also provides a low-reactivity active cement material obtained by incorporating the raw material cement with less than the theoretical amount of water necessary for hydration of the raw material cement. By using the low-reactivity active cement material of the present invention for adding a hydrated cured product, self-healing ability can be imparted to the resulting hydrated cured product.
The cement used in the present invention is selected from, for example, various portland cements such as normal, moderately hot, low heat, early strength, super early strength, sulfate resistance, mixed cements such as blast furnace cement, fly ash cement and silica cement. At least one type can be mentioned, and specific examples include Portland cement, blast furnace cement, silica cement, fly ash cement and the like defined by JIS R 5210, JIS R 5211, JIS R 5212, JIS R 5213, and the like.
Moreover, as the raw material cement used as the raw material of the low reaction activity cement material of the present invention, the same cement as the above cement is used. In particular, the low heat Portland cement specified in JIS R 5210 is most preferable.
The water used for the self-healing hydrated cured product of the present invention is not particularly limited, and may be tap water.
Moreover, it does not specifically limit about the water used as a raw material of the low reaction activity cement material of this invention, Tap water may be sufficient.
If desired, the self-healing hydrated cured product of the present invention can further contain fine aggregate. Fine aggregates include, for example, mountain sand, land sand, sea sand, river sand, crushed sand, blast furnace slag fine aggregate, ferronickel slag fine aggregate, copper slag fine aggregate used in ordinary mortar and concrete, An electric furnace oxidation slag, etc. are mentioned. The fine aggregate preferably has a fine particle amount of 5% by mass or less, more preferably 3% by mass or less, determined by the method of JIS A 1103 “Aggregate Fine Particle Amount Test Method”.
In addition, the self-healing hydrated cured product of the present invention may further contain a coarse aggregate as desired. Examples of the coarse aggregate include river gravel, mountain gravel, land gravel, sea gravel, crushed stone, blast furnace slag coarse aggregate, electric furnace oxidation slag, and the like.
Both fine and coarse aggregates to be used are selected to have the quality that satisfies the required strength.
The low-reactivity cement material of the present invention is obtained by adding less than the theoretical amount of water necessary for hydration of the raw cement to the raw cement, and this low-reactivity cement material is mixed with water in advance. The reaction activity is different from that of cement. That is, when the self-healing hydrated cured product of the present invention containing cement, water, and the low-reactivity active cement material of the present invention is prepared, the cement reacts preferentially and is self-reacted by the cement reaction. Most of the water in the cured hydrated cured product is consumed. Then, there is a lack of water sufficient for the reaction of the low-reactivity active cement material, and most of this material remains as unreacted nuclei. The low-reactivity active cement material that has existed as unreacted nuclei gradually reacts with water supplied from the outside once cracks occur in the cured body of the self-healing hydrated cured product. The hydrate precipitated by the reaction between the low-reactivity cement material and water fills the cracks, thereby realizing self-repair of cracks.
Here, the theoretical amount of water necessary for hydration of the raw cement is the amount of chemically bonded water when all the raw cement is hydrated, and is included in the hydrate when the raw cement particles react with water. The total amount of water that is physically immobilized.
The low reaction activity cement material of the present invention is preferably obtained by containing 5 to 25 parts by mass of water with respect to 100 parts by mass of the raw material cement, and more preferably obtained by containing 5 to 10 parts by mass of water. What is obtained by containing 5-7 mass parts of water is more preferable. If the amount of water contained in the raw material cement is 5 parts by mass or more, the reaction activity of the raw material cement is sufficiently reduced, and if it is 25 parts by mass or less, unreacted nuclei remain in the resulting low-reactivity active cement material. In any case, the effects of the present invention are remarkably exhibited.
The low-reactivity cement material is preferably one obtained by adding water to the raw material cement and holding it for 3 days or more, more preferably one obtained by holding for 7 to 28 days, and 7 to 14 days. What is obtained by holding is more preferable. When the retention period after adding water to the raw material cement is 3 days or more, the reaction activity of the raw material cement is sufficiently lowered, and thus the effect of the present invention is more remarkably exhibited.
The raw material cement may contain water as long as the raw material cement and water are mixed uniformly to some extent. For example, a predetermined amount of raw material cement is mixed with measured water using a mixer. A method is mentioned.
The low-reactivity active cement material of the present invention thus obtained is in the form of secondary particles in which the raw material cement particles are aggregated and bonded by contact between the raw material cement and water. Therefore, the average particle size of the raw material cement is generally about 10 μm, whereas the average particle size of the low reaction activity cement material of the present invention is preferably 20 to 70 μm, more preferably 40 to 50 μm. The average particle size is the number average particle size of particle size distribution measured by a laser diffraction / scattering method (microtrack method).
When the low-reactivity active cement material of the present invention is blended as a material for self-healing hydrated and cured products such as mortar and concrete, it is replaced with a part or all of fine aggregate used in blending of mortar and concrete. It is good to use it.
  In the self-healing hydrated cured product of the present invention, the ratio of the low-reactivity active cement material to the fine aggregate is preferably 10:90 to 20:80 by mass ratio, and 10:90 to 15: More preferably, it is 85. If the ratio of the low-reactivity active cement material is smaller than the above range, the filling of the cracked portion becomes insufficient, and sufficient self-healing ability is not expressed. Since the fluidity of the resulting self-healing hydrated cured product is greatly reduced, it is not preferred in practice.
  Moreover, the water cement ratio in the self-healing hydrated cured product of the present invention is preferably 15 to 50% by mass ratio, and more preferably 15 to 40%. The low-reactivity active cement material contained in the self-healing hydrated cured product of the present invention is not included in the cement content in the water cement ratio.
  If desired, the self-healing hydrated cured product of the present invention can further contain silica fume. Silica fume is a spherical ultrafine particle material with a particle size of about 0.1 to 0.3 μm mainly composed of amorphous silicon dioxide produced as a by-product during the production of metallic silicon and ferrosilicon. The cured body is densified by high pozzolanic activity and microfiller effect, and the strength is enhanced.
  Further, the self-healing hydrated cured product of the present invention can contain a water reducing agent as desired. Examples of the water reducing agent include a high performance water reducing agent and a high performance AE water reducing agent which is a polycarboxylate-based water reducing agent. The high-performance water reducing agent is mainly composed of either a polyalkylallyl sulfonate system or a melamine formalin resin sulfonate system.
Examples of the polyalkylallylsulfonate-based high-performance water reducing agent include methyl naphthalene sulfonic acid formalin condensate, naphthalene sulfonic acid formalin condensate, and anthracene sulfonic acid formalin condensate. ) Product name "FT-500" and its series, product name "Mighty-100 (powder)" and "Mighty-150" and its series made by Kao Corporation, products made by Daiichi Kogyo Seiyaku Co., Ltd. The name “Cellflow 110P (powder)”, the product name “Pole Fine 510N” manufactured by Takemoto Yushi Co., Ltd., and the like can be given. Melamine formalin resin sulfonate-based high-performance water reducing agent includes Grace Chemicals' product name “FT-3S”, Showa Denko Co., Ltd. product name “Molmaster F-10 (powder)” and “Molmaster F”. -20 (powder) ".
The polycarboxylate-based high-performance AE water reducing agent includes a product name “Leo Build SP8” series manufactured by NM Co., Ltd., a product name “Floric SF500” series manufactured by Floric Co., Ltd., and Takemoto Yushi Co., Ltd. Product name “Chupor HP8,11” series, product name “Darlex Super 100, 200, 300, 1000” series manufactured by Grace Chemicals Co., Ltd., “Mighty 21WH, 3000S” manufactured by Kao Corporation, etc. Other commercial products are also used.
The amount of the high-performance water-reducing agent and high-performance AE water-reducing agent used is usually about 1.0 to 3.0 parts by mass with respect to a total of 100 parts by mass of the cement, water, fine aggregate and low-reactivity active cement material. .
Reference Example 100 parts by weight of early strength Portland cement and 200 parts by weight of standard sand specified in JIS R 5201 Annex 3 were added to a biaxial forced kneading mixer, stirred for 30 seconds, and then 50 parts by weight of water was added. And kneaded for 3 minutes to prepare a mortar. The composition of the mortar is shown in Table 2.
Immediately after mortar preparation, mortar flow was measured. The mortar flow was in accordance with JIS R 5201 “Cement physical test method”, and a comparative study was conducted with a zero stroke flow that did not give a drop motion after pulling up the flow cone. The measured mortar flow is shown in Table 2.
Next, a specimen of 100 mm × 100 mm × 120 mm was produced from the mortar thus obtained. Seven days after the specimen preparation, a split tensile load was applied to introduce cracks having a width of 0.1 to 0.2 mm.
The following water permeability tests were performed on the specimens with cracks introduced as described above.
(Water permeability test)
Seven days after the introduction of the crack, a water permeation pressure of 0.01 Mpa was applied to the cracked portion at the top of the specimen by a compressor, and the amount of permeation to the bottom of the specimen per unit time was measured. Thereafter, the water permeability test was conducted in the same manner 28, 56, 91, and 182 days after the crack was introduced. About the water permeability test performed 7 to 182 days after the crack introduction, it is shown in Table 3 as the water permeability ratio calculated by (water permeability at each time) / (water permeability measured 7 days after the crack introduction).
Example 1 (Preparation of low reaction activity cement material)
5 parts by weight of water was added to 100 parts by weight of ordinary Portland cement (cement N), mixed with a mixer, and allowed to stand for 7 days under an air temperature of 20 ° C. and a humidity of 60% to obtain a low-reactivity active cement material. .
Example 2 (Preparation of self-healing hydrated cured product)
20 to 40 parts by mass of the low-reactivity active cement material obtained in Example 1, 100 parts by mass of early strength Portland cement, and 160 to 180 parts by mass of standard sand defined in JIS R 5201 Annex 3 as two fine aggregates. The mixture was put into a shaft forced kneading mixer and stirred for 30 seconds, and then 50 parts by mass of water was added and kneaded for 3 minutes to prepare a mortar. Table 1 shows the type of cement, the amount of water input, and the standing period, and Table 2 shows the composition of the mortar. Further, the mortar flow of the prepared mortar was measured in the same manner as in the reference example. The mortar flow is shown in Table 2.
Next, a specimen of 100 mm × 100 mm × 120 mm was produced from the mortar thus obtained. Seven days after the specimen preparation, a split tensile load was applied to introduce cracks having a width of 0.1 to 0.2 mm, and a water permeability test was conducted in the same manner as in the reference example. The water permeability ratio is shown in Table 3.
Examples 3 to 9 (Preparation of self-healing hydrated cured product)
A low-reactivity active cement material was obtained in the same manner as in Example 1 with the cement type, water input amount, and stationary period shown in Table 1. After preparing mortar with the composition shown in Table 2 in the same manner as in Example 2, a specimen was prepared and a water permeability test was performed. The results are shown in Table 3.
  As shown in Table 3, in the reference example, it is possible to confirm a decrease in the amount of water permeation considered to be due to clogging of cracks in the specimen due to water flow, but the mortar using the low reaction activity cement material of the present invention Then, the decrease in the water permeability is remarkable, and the expression of self-healing ability can be confirmed.
  The low-reactivity active cement material of the present invention has a property of imparting self-healing ability to mortar and concrete, and is used for various applications such as construction of structures.

Claims (3)

  1. Secondary particulate low-reactivity cement obtained by adding 5 to 25 parts by mass of water to 100 parts by mass of the raw material cement and mixing with a mixer and then holding for 3 days or more material.
  2. The low-reactivity cement material according to claim 1, wherein the average particle size is 20 to 70 µm.
  3. The low-reactivity active cement material according to claim 1 or 2 , which is used for adding a hydrated cured product.
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