Solidification material

Abstract

To provide a solidification material capable of effectively utilizing a raw concrete sludge and having excellent strength development and fluidity.SOLUTION: A solidification material comprises a cement-based solidification material and raw concrete sludge powder, wherein an insoluble residue of the raw concrete sludge powder exceeds 10.0 mass% and a ratio of the raw concrete sludge powder in the solidification material is 10.0 mass% or less. A method for producing the solidification material includes: a step of measuring an insoluble residue of a raw concrete sludge; a step of examining whether a condition that a value of the insoluble residue exceeds 10.0 mass% is satisfied, and if the condition is satisfied, selecting the raw concrete sludge as a material for the solidification material; a step of drying the selected raw concrete sludge to obtain a dried raw concrete sludge; a step of pulverizing the dried raw concrete sludge to obtain a raw concrete sludge powder; and a mixing step of mixing the obtained raw concrete sludge powder and the cement-based solidification material to obtain the solidification material.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a solidifying material using fresh concrete sludge.

Background Art

[0002] In a concrete factory, a construction site, or the like, after adding water to the surplus concrete and separating the aggregates, most of the fresh concrete sludge remaining is discarded, and the problem is that it is not sufficiently recycled. As a cement-based solidifying material that effectively uses fresh concrete sludge, Patent Document 1 describes that in thermogravimetric analysis (TG) measured from 25°C to 1,000°C at a heating rate of 10°C / min in a nitrogen stream, the mass reduction amount at 400 to 500°C is 0.5 to 4.5% by mass, the mass reduction amount at 600 to 800°C is 3.5 to 8.5% by mass, and it contains 3 to 10% by mass of acid-insoluble residue (insol) and 45 to 60% by mass of calcium oxide, and the Blaine specific surface area is 5,000 to 10,000 cm 2 / g, and a cement-based solidifying material containing heated and dried powder of concrete sludge is described.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The amount of discarded fresh concrete sludge is estimated to be 2 to 3% by mass of the fresh concrete produced in a fresh concrete factory. For this reason, the cost of discarding fresh concrete sludge and the amount of carbon dioxide emitted in the production of the materials used as raw materials for the discarded concrete are problems, and the effective utilization of fresh concrete sludge is required. An object of the present invention is to provide a solidifying material that can effectively utilize fresh concrete sludge and has excellent strength development and fluidity.

Means for Solving the Problems

[0005] As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by a cement-based solidifying material and a solidifying material containing fresh concrete sludge powder having an insoluble residue (Insol.) exceeding 10.0% by mass at a ratio of 10.0% by mass or less, and completed the present invention. That is, the present invention provides the following [1] to [4]. [1] A solidifying material containing a cement-based solidifying material and fresh concrete sludge powder, wherein the insoluble residue (Insol.) of the fresh concrete sludge powder exceeds 10.0% by mass, and the ratio of the fresh concrete sludge powder in the solidifying material is 10.0% by mass or less. [2] The solidifying material according to [1], wherein the water content of the fresh concrete sludge powder is 3.0% by mass or less. [3] The solidifying material according to [1] or [2], wherein the Blaine specific surface area of the fresh concrete sludge powder is 3,000 cm 2 / g or more.

[0006] [4] A method for manufacturing the solidifying material according to any one of [1] to [3] above, comprising: an insoluble residue measurement step of measuring the insoluble residue (Insol.) of fresh concrete sludge for which the suitability as a material for the solidifying material is to be determined; a selection step of examining whether or not the value of the insoluble residue (Insol.) obtained in the insoluble residue measurement step exceeds 10.0% by mass, and if the above condition is satisfied, selecting the fresh concrete sludge as a material for the solidifying material; a drying step of drying the fresh concrete sludge selected as a material for the solidifying material in the selection step to obtain dried fresh concrete sludge; a pulverization step of pulverizing the dried fresh concrete sludge obtained in the drying step to obtain fresh concrete sludge powder; and a mixing step of mixing the fresh concrete sludge powder obtained in the pulverization step with a cement-based solidifying material to obtain the solidifying material. The method for manufacturing a solidifying material is characterized by including these steps.

Effect of the Invention

[0007] Since the solidifying material of the present invention uses fresh concrete sludge as a material, it is possible to effectively utilize fresh concrete sludge and reduce the amount of fresh concrete sludge to be discarded. In addition, since the amount of materials (cement, aggregates, admixtures, etc.) used as raw materials for concrete contained in the discarded fresh concrete sludge can be reduced, the amount of carbon dioxide emitted in the production of these discarded materials can be reduced. Moreover, the solidifying material of the present invention is excellent in strength development and fluidity.

Embodiments for Carrying Out the Invention

[0008] The solidifying material of the present invention is a solidifying material containing a cement-based solidifying material and fresh concrete sludge powder, wherein the insoluble residue (Insol.) of the fresh concrete sludge powder exceeds 10.0% by mass, and the proportion of the fresh concrete sludge powder in the solidifying material is 10.0% by mass or less. This will be described in detail below. In this specification, the cementitious solidifying material refers to a material that contains cement as the main material (usually 50% by mass or more) and optionally contains admixed materials that can be blended. Examples of cement used in the cementitious solidifying material include various Portland cements such as ordinary Portland cement, early-strength Portland cement, medium-heat Portland cement, low-heat Portland cement, sulfate-resistant Portland cement, etc., mixed cements such as blast furnace cement, fly ash cement, silica cement, etc., eco-cement, white cement, super-fast hard cement, and the like. Among them, from the perspective of easy availability, Portland cement is preferred. Examples of admixed materials include blast furnace slag fine powder, fly ash, silica fume, and limestone fine powder. These may be used alone or in combination of two or more.

[0009] From the perspective of making the strength development property of the solidifying material more excellent, the proportion of cement in the cementitious solidifying material is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more. In addition, when the cement is a mixed cement such as blast furnace cement, the amount of cement admixtures such as blast furnace slag fine powder contained in the mixed cement shall not be included in the above proportion of the cement.

[0010] The proportion of the cementitious solidifying material in the solidifying material is preferably 90.0 to 99.9% by mass, more preferably 90.5 to 99.5% by mass, still more preferably 95.0 to 99.0% by mass, and particularly preferably 96.0 to 98.0% by mass. If the above proportion is 90.0% by mass or more, the strength development property of the solidifying material can be further improved. If the above proportion is 99.9% by mass or less, the fluidity of the solidifying material can be further improved, and the use amount of fresh concrete sludge powder can be relatively increased to further promote the effective utilization of fresh concrete sludge.

[0011] The fresh concrete sludge used in the present invention is not particularly limited. For example, (i) water is added to the concrete remaining unused at a construction site or the like to form a slurry, and then coarse components such as aggregates (coarse aggregates and fine aggregates) contained in the slurry are separated, and the resulting product contains fine powder components such as cement; (ii) it includes those containing fine powder components such as cement obtained by separating coarse components such as aggregates from the residue containing concrete generated when washing an agitator truck or the like. Examples of the method for separating coarse components such as aggregates include a method in which coarse aggregates and fine aggregates are separated from a slurry or residue using a plurality of vibrating sieves with different mesh sizes. The separated coarse aggregates and fine aggregates are reused as aggregates. The fresh concrete sludge powder used in the present invention can be obtained by diluting the fresh concrete sludge with water as necessary, performing solid-liquid separation using a filter press or the like, drying the obtained solid content, and then crushing or pulverizing it and classifying it as necessary.

[0012] The insoluble residue (Insol.) of the fresh concrete sludge powder exceeds 10.0% by mass, preferably 10.5 - 30.0% by mass, more preferably 11.0 - 25.0% by mass, still more preferably 12.0 - 20.0% by mass, and particularly preferably 13.0 - 15.0% by mass. When the above insoluble residue exceeds 10.0% by mass and is 30.0% by mass or less, the strength development property of the solidifying material is further improved. When the above insoluble residue is 10.0% by mass or less, the fluidity of the solidifying material decreases.

[0013] From the viewpoint of improving the strength development property of the solidifying material, the water content of the fresh concrete sludge powder is preferably 3.0% by mass or less, more preferably 2.0% by mass or less, and particularly preferably 1.0% by mass or less. The water content of the fresh concrete sludge powder can be calculated, for example, using the following formula from the masses of the fresh concrete sludge powder before and after heating the fresh concrete sludge powder at 105°C using an electric furnace or the like until it reaches a constant mass. Water content (%) of fresh concrete sludge powder = [(mass of fresh concrete sludge powder before heating) - (mass of fresh concrete sludge powder after heating)] / (mass of fresh concrete sludge powder before heating) × 100

[0014] The proportion of fresh concrete sludge powder in the solidifying agent is 10% by mass or less, preferably 0.1 - 9.8% by mass, more preferably 0.5 - 9.5% by mass, still more preferably 1.0 - 5.0% by mass, and particularly preferably 2.0 - 4.0% by mass. If the above proportion is 0.1% by mass or more, the fluidity of the solidifying agent can be further improved, and the amount of fresh concrete sludge powder used can be relatively increased to further promote the effective utilization of fresh concrete sludge. If the above proportion is 10.0% by mass or less, the strength development property of the solidifying agent can be further improved. The Blaine specific surface area of the fresh concrete sludge powder is preferably 3,000 cm 2 / g or more, more preferably 4,000 - 10,000 cm 2 / g, still more preferably 5,000 - 8,000 cm 2 / g, and particularly preferably 6,000 - 7,000 cm 2 / g. If the above Blaine specific surface area is 3,000 cm 2 / g or more, the strength development property of the solidifying agent can be further improved. If the above Blaine specific surface area is 10,000 cm 2 / g or less, the fluidity of the solidifying agent can be further improved.

[0015] As an example of a method for manufacturing the above-described solidifying material, (A) an insoluble residue measurement step of measuring the insoluble residue (Insol.) of the fresh concrete sludge for which the suitability as a material for the solidifying material is to be determined; (B) a selection step of examining whether or not the value of the insoluble residue (Insol.) obtained in the insoluble residue measurement step exceeds 10.0% by mass, and if the above condition is satisfied, selecting the fresh concrete sludge as a material for the solidifying material; (C) a drying step of drying the fresh concrete sludge selected as a material for the solidifying material in the selection step to obtain dried fresh concrete sludge; (D) a pulverizing step of pulverizing the dried fresh concrete sludge obtained in the drying step to obtain fresh concrete sludge powder; and (E) a mixing step of mixing the fresh concrete sludge powder obtained in the pulverizing step with a cement-based solidifying material to obtain a solidifying material. Hereinafter, each step will be described in detail.

[0016] [(A) Insoluble Residue Measurement Step] Step (A) (insoluble residue measurement step) is a step of measuring the insoluble residue (Insol.) of the fresh concrete sludge for which the suitability as a material for the solidifying material is to be determined. The insoluble residue of the fresh concrete sludge can be measured in accordance with "JIS R 5202:2010 (Chemical Analysis Method for Cement)". [(B) Selection Step] Step (B) (selection step) is a step of examining whether or not the value of the insoluble residue (Insol.) obtained in the insoluble residue measurement step exceeds 10.0% by mass, and if the above condition is satisfied, selecting the fresh concrete sludge as a material for the solidifying material. In step (B), the fresh concrete sludge that does not satisfy the above condition is not selected as a material for the solidifying material of the present invention, but is used for another purpose or disposed of as waste. The above condition may be appropriately changed in consideration of the quality of the target solidifying material, the amount of use of the fresh concrete sludge powder, and the like. For example, the condition of the value of the insoluble residue (Insol.) of the fresh concrete sludge powder may be determined within the preferable numerical range of 10.5 to 30.0% by mass, 11.0 to 25.0% by mass, 12.0 to 20.0% by mass, or 13.0 to 15.0% by mass of the insoluble residue (Insol.) of the fresh concrete sludge powder described above. In steps (A) to (B), the fresh concrete sludge whose suitability as a material for the solidifying agent is judged may be one type or two or more types. For each of a plurality of types of fresh concrete sludge prepared in advance, by performing steps (A) to (B), fresh concrete sludge satisfying the above conditions can be selected as a material for the solidifying agent from the plurality of types of fresh concrete sludge.

[0017] [(C) Drying step] Step (C) (drying step) is a step of drying the fresh concrete sludge selected as a material for the solidifying agent in the selection step to obtain dried fresh concrete sludge. The method for drying the fresh concrete sludge is not particularly limited, and examples thereof include a method of drying using a rotary kiln or an electric furnace, a method of drying by sun drying, and the like. Drying is preferably carried out until the water content of the dried fresh concrete sludge is preferably 3.0% by mass or less, more preferably 2.0% by mass or less, and particularly preferably 1.0% by mass or less, from the viewpoint of facilitating the subsequent pulverization step. The water content (% by mass) of the dried fresh concrete sludge can be calculated using the following formula from the masses of the fresh concrete sludge before and after heating, for example, by heating the fresh concrete sludge after drying at 105 °C using an electric furnace or the like until the fresh concrete sludge reaches a constant mass. Water content (% by mass) of dried fresh concrete sludge = [(mass of fresh concrete sludge before heating) - (mass of fresh concrete sludge after heating)] / (mass of fresh concrete sludge before heating) × 100 Also, before performing the drying step, solid-liquid separation may be performed on the fresh concrete sludge to remove some of the water in the fresh concrete sludge in advance.

[0018] [(D) Crushing Process] Process (D) (the crushing process) is a process of crushing the dried fresh concrete sludge obtained in the drying process to obtain fresh concrete sludge powder. As an example of a method for crushing the dried fresh concrete sludge, a method of performing fine crushing of the obtained crushed material after performing coarse crushing of the dried fresh concrete sludge can be mentioned. Coarse crushing of the dried fresh concrete sludge can be performed using various coarse crushing means such as a jaw crusher, an impact crusher, etc. Coarse crushing is preferably performed until all of the crushed material of the dried fresh concrete sludge can pass through a sieve with an aperture of 20 mm. Fine crushing of the crushed material of the dried fresh concrete sludge can be performed using various fine crushing means such as a tube type ball mill, a vertical mill, etc. Fine crushing is preferably performed until, for example, the Blaine specific surface area of the obtained finely crushed material (fresh concrete sludge powder) is 3,000 cm 2 / g or more, more preferably 4,000 to 10,000 cm 2 / g, even more preferably 5,000 to 8,000 cm 2 / g, particularly preferably 6,000 to 7,000 cm 2 / g.

[0019] [(E) Mixing Process] Process (E) (the mixing process) is a process of mixing the fresh concrete sludge powder obtained in the crushing process and a cementitious solidifying material to obtain a solidifying material. The method for mixing various materials is not particularly limited, and for example, a method of mixing using mixing means such as a Henschel mixer can be mentioned. Also, after separately preparing the cementitious solidifying material and the fresh concrete sludge powder, the cementitious solidifying material and the fresh concrete sludge powder in an amount such that the blending ratio of the cementitious solidifying material and the fresh concrete sludge powder in the solidifying material becomes a desired blending ratio are sprayed onto the soil to be solidified, and then mixed by stirring together with the above soil.

[0020] According to the solidifying material of the present invention, the strength (for example, uniaxial compression strength) of the solidified improved soil formed by mixing the solidifying material and the soil can be increased. As an example of the method for solidifying soil using the solidifying material of the present invention, a method of adding and mixing the above-described solidifying material to the target soil to obtain solidified improved soil can be mentioned. The addition amount of the solidifying material to the soil varies depending on the properties of the target soil, construction conditions, the strength required for the solidified improved soil obtained after the solidification treatment, etc. However, per 1 m of the soil to be solidified 3 of the target, it is preferably 10 to 400 kg, more preferably 20 to 300 kg, and particularly preferably 25 to 150 kg. If the addition amount is 10 kg or more, the strength (for example, uniaxial compression strength) of the solidified improved soil can be further increased. If the addition amount is 300 kg or less, an increase in cost can be prevented.

[0021] As the method for adding and mixing the solidifying material to the soil, there are dry addition in which the solidifying material is added to the target soil as a powder and mixed, and slurry addition in which water is added to the solidifying material to form a slurry, and the slurry is added and mixed. The mass ratio of water / solidifying material in the case of slurry addition is preferably 0.6 to 1.5, more preferably 0.8 to 1.2.

Examples

[0022] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. [Materials Used] (1) Cement-based solidifying material; manufactured by Taiheiyo Cement Corporation, trade name "GeoSet", cement content: 90% by mass or more (2) Fresh concrete sludge A to F; each having a different origin (3) Soil A; volcanic wet clay (4) Soil B; cohesive soil (5) Soil C; organic volcanic ash soil

[0023] [Examples 1 to 4, Comparative Examples 1 to 3] Regarding the raw concrete sludge of the type shown in Table 1, the insoluble residue of the raw concrete sludge was measured in accordance with "JIS R 5202:2010 (Chemical Analysis Method for Cement)". Also, the raw concrete sludge was dried using a rotary kiln until the water content of the raw concrete sludge became 1.0 mass% or less. The dried raw concrete sludge was crushed using a jaw crusher and an impact crusher. The crushing was carried out until all of the resulting crushed material could pass through a sieve with an opening size of 20 mm. Also, the obtained crushed material was finely pulverized using a vertical mill to obtain raw concrete sludge powder (water content: 1.0 mass% or less). The Blaine specific surface area of the obtained powder (shown as "Blaine" in Table 1) was measured in accordance with "JIS R 5201:2015 (Physical Testing Methods for Cement)".

[0024] A cementitious solidifying material (shown as "base material" in Table 1) and the obtained raw concrete sludge powder (shown as "sludge powder" in Table 1) were mixed using a Henschel mixer at the blending ratios shown in Table 1 to obtain a solidifying material. The obtained solidifying material was evaluated using the following method. The measurement was carried out in an environment at 30°C. [Measurement of P-funnel flow time] As an index for evaluating the fluidity of the solidifying material slurry, the P-funnel flow times immediately after kneading, 15 minutes after kneading, 30 minutes after kneading, 60 minutes after kneading, and 90 minutes after kneading of the solidifying material slurry obtained by mixing water and the solidifying material so that the mass ratio of water to the solidifying material (water / solidifying material) is 0.6 were measured. The P-funnel flow time is the time from when 1.725 liters of the solidifying material slurry is poured into the P-funnel defined in "Civil Engineering Society Standard JSCE-F 521-1999 (Test Method for Fluidity of Injection Mortar for Prepacked Concrete (Method Using P-Funnel))" until the outflow of the solidifying material slurry from the outlet of the P-funnel first stops after the outflow of the solidifying material slurry starts. It should be noted that the shorter the P-funnel flow time, the better the fluidity of the solidifying material slurry can be judged.

[0025] [Measurement of uniaxial compressive strength] A solidifying material slurry obtained by mixing water and a solidifying material so that the mass ratio of water to the solidifying material (water / solidifying material) is 0.6 was added and mixed in an amount of 400 kg per 1 m of Soil A, and Soil A was solidified in accordance with "JCAS L-01:2006 (Test method for strength of improved body by cement-based solidifying material)" to obtain a specimen of solidified improved soil A. 3 The uniaxial compressive strength of the obtained specimen of solidified improved soil A at 28 days of age was measured in accordance with "JIS A 1216:2020 (Test method for uniaxial compression of soil)". Also, the solidifying material was added and mixed in an amount of 100 kg per 1 m of Soil B to obtain a specimen of solidified improved soil B obtained by solidifying Soil B. The uniaxial compressive strength of the obtained specimen of solidified improved soil B at 28 days of age was measured in the same manner as that of solidified improved soil A. In addition, the solidifying material was added and mixed in an amount of 100 kg per 1 m of Soil B to obtain a specimen of solidified improved soil B obtained by solidifying Soil B. The uniaxial compressive strength of the obtained specimen of solidified improved soil B at 28 days of age was measured in the same manner as that of solidified improved soil A. 3 The solidifying material was added and mixed in an amount of 100 kg per 1 m of Soil B to obtain a specimen of solidified improved soil B obtained by solidifying Soil B. The uniaxial compressive strength of the obtained specimen of solidified improved soil B at 28 days of age was measured in the same manner as that of solidified improved soil A. [Measurement of CBR] The solidifying materials prepared in Example 1 and Comparative Example 3 were added and mixed in the amounts shown in Table 2 (50 kg, 100 kg, 150 kg) per 1 m of Soil C to obtain solidified improved soil obtained by solidifying Soil C. The specimens of the obtained solidified improved soil were molded in accordance with "Pavement Survey and Test Handbook, 2019 Edition (edited by Japan Road Association), Chapter III, 6-4, Test Method for CBR of Stabilized Soil", and the CBR (California Bearing Ratio) at 7 days of age was measured in accordance with "JIS A 1211:2020 (CBR Test Method)". 3 Note that the larger the values of uniaxial compressive strength and CBR, the better the strength development property of the solidifying material. Note that the larger the values of uniaxial compressive strength and CBR, the better the strength development property of the solidifying material.

[0026] [Comparative Example 3] The solidifying material was evaluated in the same manner as in Example 1, except that a solidifying material consisting only of a cement-based solidifying material was used. The respective results are shown in Tables 1 and 2.

[0027]

Table 1

[0028]

Table 2

[0029] From Tables 1 and 2, it can be seen that the P funnel flow-down times of Examples 1 to 4 are all smaller than those of Comparative Examples 1 to 3. When the solidifying material of the present invention is used in the form of a slurry, the slurry has excellent fluidity. In addition, the uniaxial compression strengths of Soils A to B after solidification treatment in Examples 1 to 4 are all greater than those of Soils A to B after solidification treatment in Comparative Examples 1 to 3. It can be seen that the solidifying material of the present invention has excellent strength development property. In addition, the CBR of Soil C after solidification treatment in Example 1 is greater than the CBR of Soil C after solidification treatment in Comparative Example 3. It can be seen that the solidifying material of the present invention has excellent strength development property.

Claims

1. A solidifying material containing a cement-based solidifying material and fresh concrete sludge powder, wherein the insoluble residue (Insol.) of the fresh concrete sludge powder exceeds 10.0% by mass, and the proportion of the fresh concrete sludge powder in the solidifying material is 10.0% by mass or less. A solidifying material characterized by this.

2. The solidifying material according to Claim 1, wherein the water content of the fresh concrete sludge powder is 3.0% by mass or less.

3. The Blaine specific surface area of the above raw concrete sludge powder is 3,000 cm ２ / g or more, and the solidifying material according to claim 1 or 2.

4. A method for producing the solidifying material according to Claim 1, an insoluble residue measurement step of measuring the insoluble residue (Insol.) of fresh concrete sludge for which the suitability as a material for the solidifying material is to be determined; a selection step of examining whether or not the value of the insoluble residue (Insol.) obtained in the insoluble residue measurement step satisfies the condition of exceeding 10.0% by mass, and selecting the fresh concrete sludge as a material for the solidifying material when the condition is satisfied; a drying step of drying the fresh concrete sludge selected as a material for the solidifying material in the selection step to obtain dried fresh concrete sludge; a pulverization step of pulverizing the dried fresh concrete sludge obtained in the drying step to obtain fresh concrete sludge powder; and a mixing step of mixing the fresh concrete sludge powder obtained in the pulverization step and a cement-based solidifying material to obtain the solidifying material. A method for producing a solidifying material, characterized by including these steps.

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