JP2010285465A - Ground-improving slurry composition using blast furnace cement composition and method for preparing soil cement slurry using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground-improving slurry composition which ensures good applicability in ground-improving constructions, uses blast furnace slag powder in a higher rate than the present slurry compositions to give ground-cured products having necessary strengths, and can inhibit the generation of carbon dioxide, and to provide a method for preparing a soil cement slurry using the same. <P>SOLUTION: This ground-improving slurry composition is characterized by using the following blast furnace cement composition as a binder to prepare a water/the blast furnace cement composition in a mass ratio of 40 to 250%, and containing an admixture in an amount of 0.1 to 5 pts.mass per 100 pts.mass of the blast furnace cement composition. The blast furnace cement composition is prepared by adding 10 to 30 pts.mass of reclaimed concrete powder having a calcium hydroxide content of 3 to 15 mass% and separated from crushed concrete to 100 pts.mass of a mixture comprising 60 to 90 mass% of blast furnace slag powder having a fineness of 3,000 to 8,000 cm<SP>2</SP>/g, 5 to 20 mass% of gypsum and 5 to 35 mass% of Portland cement (totally 100 mass%). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a slurry composition for ground improvement using a blast furnace cement composition and a method for preparing a soil cement slurry using the same. In recent years, there has been an increasing demand for reduction of carbon dioxide emissions and improvement of energy consumption efficiency. In view of such circumstances, blast furnace granulated slag produced as a by-product from steelworks is also effectively used as a raw material for blast furnace cement in the form of fine blast furnace slag powder, even in mountain construction, underground water stop construction, soft ground improvement work, etc. ing. In general, when performing ground improvement as described above, a cement slurry (cement milk) mixed with cement-based solidification material and water is poured into the ground, and the soil and soil are in situ using a drilling kneading machine. Here, blast furnace cement is used as a cement-based solidifying material. Blast furnace cement is made by mixing ordinary Portland cement with blast furnace slag fine powder. According to the standard of JIS-R5211, depending on the amount of fine blast furnace slag powder, type A (over 5% to 30%), type B (30% Although it is divided into three types of super--60%) and C-type (over 60% -70%), blast furnace cement B-type having a good performance balance is frequently used in the field of actual ground improvement. Blast furnace cement B species in soil improvement is being mixed in a ratio of 100~400kg in the ground 1 m ³ is typically emit carbon dioxide of about 400kg to produce a blast furnace cement B One case ton plant since it has to, in order to improve the ground 1 m ³ using a blast furnace cement type B, with the exception of carbon dioxide emissions generated by the transportation or the like of the construction machine operation and materials, emit carbon dioxide 40~160kg Will be. Therefore, in the field of ground improvement, carbon dioxide is generated by using a higher proportion of blast furnace slag fine powder on the premise that the improved ground will have the required strength while ensuring workability. The emergence of technology to suppress this is required. The present invention relates to a ground improvement slurry composition using a blast furnace cement composition that meets such requirements, and a method for preparing a soil cement slurry using the same.

  Conventionally, about the influence when Portland cement is used for ground improvement, Portland cement produces alkalinity because it generates calcium hydroxide when it comes into contact with water, and when this is used for ground improvement, the pH of the ground rises to about 10 and plant If Portland cement is used to improve the soil with low water content such as loam layer, hexavalent chromium contained in Portland cement will be easily dissolved and adversely affect the environment. (For example, refer nonpatent literature 1). Separately, proposals for improving the fluidity of cement slurry used for ground improvement (for example, see Patent Documents 1 to 3) and proposals for hydraulic compositions using blast furnace slag that can also be applied to ground improvement (for example, patents) There are no specific reports or proposals that contribute to the reduction of carbon dioxide emissions.

Japanese Patent Laid-Open No. 11-256161 JP 2000-169209 A JP 2006-298726 A JP-A-62-158146 JP-A 63-2842 JP-A-1-208354 Japanese Patent Laid-Open No. 10-114555 Japanese Patent Laid-Open No. 2002-241152

"Ground improvement manual by cement-based solidifying material", edited by Cement Association, 1984, pp. 42-44.

  The problem to be solved by the present invention is to use blast furnace slag fine powder at a higher rate than the present, assuming that the ground hardened body has the required strength while ensuring workability in ground improvement work. Thus, the present invention provides a slurry composition for ground improvement that suppresses the generation of carbon dioxide and a method for preparing a soil cement slurry using the same.

  As a result, the present inventors have studied to solve the above-mentioned problems. As a result, the ground containing a specific blast furnace cement composition containing a high proportion of blast furnace slag fine powder and a low content of Portland cement together with an admixture. It has been found that a slurry composition for improvement and a method for preparing a soil cement slurry using the same are correctly suitable.

  That is, the present invention is a slurry composition for ground improvement comprising at least a binder, water and an admixture, wherein the following blast furnace cement composition is used as a binder and water / mass of the blast furnace cement composition is used. The ground using the blast furnace cement composition, wherein the ratio is adjusted to 40 to 250%, and the admixture is contained in an amount of 0.1 to 5 parts by mass per 100 parts by mass of the blast furnace cement composition It relates to a slurry composition for improvement.

Blast furnace cement composition: 60 to 90% by mass of fine powder of blast furnace slag having a fineness of 3000 to 13000 cm ² / g, 5 to 20% by mass of gypsum, and 5 to 35% by mass of Portland cement (total 100% by mass) A blast furnace cement composition in which a reclaimed concrete fine powder having a calcium hydroxide content of 3 to 15% by mass separated from demolition concrete is added at a rate of 10 to 30 parts by mass per 100 parts by mass of the mixture.

The present invention, the ground improvement slurry compositions using blast furnace cement composition of the present invention, according to the method of preparing a soil cement slurries which comprises using a ratio of 300~1200kg per soil 1 m ^3.

The slurry composition for ground improvement using the blast furnace cement composition according to the present invention (hereinafter referred to as the slurry composition of the present invention) contains at least a binder, water and an admixture. The slurry composition of the present invention uses a specific blast furnace cement composition as a binder, and the blast furnace cement composition contains 60 to 90% by mass of fine blast furnace slag powder having a fineness of 3000 to 13000 cm ² / g. The content of calcium hydroxide separated from the demolished concrete is 3 to 15% by mass per 100 parts by mass of the mixture containing 5 to 20% by mass of gypsum and 5 to 35% by mass (total 100% by mass) of Portland cement. The recycled concrete fine powder is added at a ratio of 10 to 30 parts by mass.

The blast furnace slag fine powder has a fineness of 3000 to 13000 cm ² / g, preferably 3000 to 8000 cm ² / g, more preferably 3500 to 6500 cm ² / g. use. When the powder having a fineness outside the range of 3000 to 13000 cm ² / g is used, the fluidity of the prepared slurry composition is deteriorated, or the strength expression of the ground using this is lowered. In the present invention, the fineness is expressed by the specific surface area by the Blaine method.

Examples of the gypsum include anhydrous gypsum, dihydrate gypsum, and hemihydrate gypsum, and anhydrous gypsum is preferable. Any anhydrous gypsum can be used as long as it contains 90% by mass or more, and natural anhydrous gypsum, by-product anhydrous gypsum, and the like can be used. Fineness is preferably a 2500~8000cm ² / g, more preferably from 3000~6500cm ² / g.

  Further, examples of Portland cement include ordinary Portland cement, early-strength Portland cement, moderately hot Portland cement, low heat Portland cement and the like, but ordinary Portland cement is preferable.

And as a recycled concrete fine powder, it is preferable to use a thing with a fineness of 2000-7000 cm < ² > / g. Moreover, although calcium hydroxide content rate uses 3-15 mass%, Preferably a 6-12 mass% thing is used. The method of separating from demolition concrete is not particularly limited, and examples thereof include a method of crushing using a crusher and a method of crushing crushed materials with a machine. The recycled concrete fine powder separated from the demolished concrete can be obtained, for example, by removing coarse aggregate or fine aggregate from the demolished concrete. At this time, coarse aggregates and fine aggregates separated from the demolished concrete can also be used as recycled products. As a means for obtaining reclaimed concrete fine powder separated from demolition concrete and containing calcium hydroxide at the above-mentioned content rate, a mechanical rubbing method is preferred, and an eccentric rotor method among mechanical rubbing methods Is more preferable. Hereinafter, a method for producing such recycled concrete fine powder will be described. The preferred recycled concrete fine powder in the present invention is preferably produced by a mechanical rubbing method without heating from the viewpoint of reducing carbon dioxide during production and ensuring that the quality of the fine powder obtained does not vary. In particular, when manufacturing with a mechanical rubbing apparatus such as an eccentric rotor type or a planetary mill, a mechanical grinding process is performed in a sealed space to remove CO ₂ in the air in the space, or nitrogen gas, etc. By using the method of enclosing the inert gas, regenerated concrete fine powder that suppresses the decrease in the content of calcium hydroxide due to carbonation during the treatment is water that is optimal for use as an alkali stimulant as in the present invention. A fine powder having a calcium oxide content can be obtained. On the other hand, in the method of crushing demolition concrete lump using a crusher such as jaw crusher or impeller breaker, aggregate and mortar paste are simultaneously crushed, so aggregate powder in recycled concrete powder increases. In addition, the ratio of aggregate powder and mortar paste powder in the fine powder varies considerably depending on the concrete arrangement (condition), and quality control is required for use as an alkali stimulant for blast furnace slag fine powder. However, the fine powder produced by the hot grinding method, which takes out the aggregate by heating and mechanical rubbing, is low in aggregate powder and is suitable as an alkali stimulating material. There is a concern that Japanese products will change, and if production energy is increased and carbon dioxide is reduced during cement production, It is hard to say that preferably also from cormorant point of view.

  In the slurry composition of the present invention, the mass ratio of the water / blast furnace cement composition is adjusted to 40 to 250%, preferably 45 to 230%. If the mass ratio is greater than 250%, the strength of the ground is greatly reduced. Conversely, if the mass ratio is less than 40%, the fluidity of the soil cement slurry is degraded. In the slurry composition of the present invention, the admixture is contained at a ratio of 0.1 to 5 parts by mass per 100 parts by mass of the blast furnace cement composition. In the present invention, the mass ratio of the water / blast furnace cement composition is obtained by (mass of water used / mass of blast furnace cement composition used) × 100.

  In the slurry composition of the present invention, examples of the admixture include those used for conventionally known soil cements. Examples thereof include a fluidizing agent and an antifoaming agent.

  Although it does not specifically limit as a fluidizing agent, The mass mean molecular weight (GPC method, pullulan conversion, the same hereafter) which carried out the alkali hydrolysis of the copolymer of an alpha olefin and maleic anhydride is 2000-70000. What consists of the alkali metal salt of a water-soluble vinyl copolymer is preferable, Especially the alkali metal of the water-soluble vinyl copolymer which hydrolyzed the copolymer of a C3-C8 alpha olefin and maleic anhydride with alkali What consists of a salt is more preferable, and what consists of the alkali metal salt of the water-soluble vinyl copolymer which alkali-hydrolyzed the copolymer of isobutylene and maleic anhydride is especially preferable.

  The fluidizing agent is also preferably composed of an alkali metal salt of polyacrylic acid having a mass average molecular weight of 1500 to 50000, which can also be used in combination with the alkali metal salt of the water-soluble vinyl copolymer. The amount of the fluidizing agent described above is 0.1 to 5 parts by mass per 100 parts by mass of the blast furnace cement composition, but preferably 0.3 to 4 parts by mass.

  The antifoaming agent is not particularly limited, and examples thereof include antifoaming agents such as polyalkylene glycol monoalkenyl (or alkyl) ether, modified polydimethylsiloxane, and trialkyl phosphate. Among these, an antifoaming agent composed of polyalkylene glycol monoalkenyl ether is preferable from the viewpoint of economic efficiency and the degree of expression of effects. The antifoaming agent eliminates troubles caused by foaming when preparing the slurry composition of the present invention, and at the same time, suppresses the entrainment of air when the slurry composition is injected into the ground and excavated and stirred. Used to increase strength development. As a usage-amount of an antifoamer, it is preferable to set it as the ratio of 0.001-0.1 mass part per 100 mass parts of blast furnace cement compositions, and it is set as the ratio of 0.002-0.01 mass part. More preferred.

  The slurry composition of the present invention can be prepared by a known method. For example, it can be prepared by a method in which predetermined amounts of blast furnace cement composition, admixture and water are put into a mixer and kneaded. At this time, additives such as bentonite and fibers, and additives such as setting retarders and curing accelerators may be added as necessary within the range not impairing the effects of the present invention.

In the fluidization method of the soil cement slurry according to the present invention, the above-described slurry composition of the present invention is mixed with soil according to the required fluidity of the soil cement slurry and the strength of the ground hardened body, and the soil cement slurry is mixed. And At this time, the slurry composition of the present invention is used so as to have a ratio of 300 to 1200 kg per 1 m ^{3 of} soil, and is preferably used so as to have a ratio of 400 to 1100 kg.

  According to the present invention, in the ground improvement work, the use of a specific blast furnace cement composition as a binder together with an admixture reduces the flowability of the prepared soil cement slurry over time while suppressing carbon dioxide emissions. It is possible to secure good workability by suppressing the above, and at the same time, it is possible to express the necessary strength for the ground cured body.

  Hereinafter, in order to make the configuration and effects of the present invention more specific, examples and the like will be described. However, the present invention is not limited to the examples. In the following examples and the like, unless otherwise indicated,% means mass%, and part means mass part.

Test category 1 (Preparation of fluidizing agent as admixture)
A flask equipped with a stirrer was charged with 145 g of water and 470 g of 30% strength sodium hydroxide, and then a copolymer of isobutylene and maleic anhydride (trade name Isoban, manufactured by Kuraray Co., Ltd.) with stirring while maintaining the internal temperature at 60 ° C. 600) Hydrolysis was carried out while gradually adding 395 g to obtain an alkali metal salt of a copolymer. When this was analyzed by GPC, it was a sodium salt (p-1) of a water-soluble vinyl copolymer having a mass average molecular weight of 23,000 and a sodium salt of a copolymer of isobutylene and maleic anhydride. In the same manner, fluidizing agents (p-2) and (p-3) were prepared.

  Table 1 summarizes the fluidizing agent and antifoaming agent used in the present invention, including the fluidizing agent.

Test Category 2 (Preparation of blast furnace cement composition)
A blast furnace cement composition (S-1) to (S-5) was prepared using the blast furnace slag fine powder, anhydrous gypsum, Portland cement and recycled concrete fine powder under the blending conditions shown in Table 2. And (R-1) to (R-6).

In Table 2,
sg-1: Ground granulated blast furnace slag with a fineness of 4100 cm ² / g sg-2: Fine ground blast furnace slag with a fineness of 5900 cm ² / g sg-3: Fine ground blast furnace slag with a fineness of 1020 cm ² / g gp- 1: Anhydrous gypsum with a fineness of 4150 cm ² / g gp-2: Anhydrous gypsum with a fineness of 5800 cm ² / g pc-1: Normal Portland cement pc-2: Early strength Portland cement rc-1: Fineness of 5860 cm ² / G and reclaimed concrete fine powder with a calcium hydroxide content of 9.2% rc-2: Recycled concrete fine powder with a fineness of 4620 cm ² / g and a calcium hydroxide content of 6.5% rc-3: Powder Recycled concrete fine powder having a degree of 4350 cm ² / g and a calcium hydroxide content of 1.5% rc-4: Fineness of 1200 cm ² / g and a calcium hydroxide content 6.1% recycled concrete fine powder

Test category 3 (Preparation of slurry composition for ground improvement)
Examples 1-10 and Comparative Examples 1-10
Under the blending conditions shown in Table 3, a predetermined amount of each of the blast furnace cement composition and kneading water (tap water) shown in Table 2 is added to the pan-type forced kneading mixer, and the flow shown in Table 1 as an admixture. Predetermined amounts of the agent and the antifoaming agent were added and kneaded to prepare a ground improvement slurry composition for each example.

In Table 3,
Types of blast furnace cement composition: those described in Table 2 Types of fluidizing agent and antifoaming agent: those described in Table 1 Amounts of fluidizing agent and antifoaming agent used: blast furnace cement composition (Comparative Examples 8 to 10) Is blast furnace cement type B) parts by mass as solids per 100 parts by mass. * 1: Blast furnace cement type B (density = 3.04 g / cm ³ , brane value 3850 cm ² / g, containing 50% Portland cement)

Test category 4 (Preparation and evaluation of soil cement slurry)
Examples 11 to 20 and Comparative Examples 11 to 21
-Preparation of soil cement slurry Using the slurry composition for ground improvement of each example prepared in Test Category 3, a soil cement slurry was prepared and evaluated as follows. Assuming that the target uniaxial compressive strength was 5 N / mm ² or more at 28 days of age, preparation of the content (kg) of the slurry composition for ground improvement per 1 m ^{3 of} soil was determined. After putting a predetermined amount of the ground improvement slurry composition prepared in Test Category 3 into a Hobart mixer, soil having the physical property values shown in Table 4 (viscous soil / silica sand obtained by excavating the ground = 3/1) A soil cement slurry of each example shown in Table 5 was prepared by adding and mixing (mixed soil mixed at (mass ratio)). The blending conditions of the soil cement in each example are shown in Table 5.

-Physical property evaluation of the prepared soil cement slurry For the prepared soil cement slurry, the flow value immediately after kneading, the flow value after 90 minutes from kneading, the air amount and the uniaxial compressive strength are determined as follows. The results are summarized in Table 5. The carbon dioxide emissions were also shown.
-Flow value: According to JIS-R5201, a flow test was performed immediately after kneading and after 90 minutes had elapsed, and the flow value (mm) after 15 drops was measured.
-Air amount: It calculated | required based on JIS-A6201 (1977 version).
-Uniaxial compressive strength test: Based on JIS-A1108, the compressive strength (N / mm < ² >) of material age 28 days was measured about the molded product shape | molded using the mold of diameter 50mm x height 100mm.

In Table 5,
Injection volume: injection amount of ground improvement slurry composition per soil 1 m ³ (kg)
Injection rate: injection ratio of ground improvement slurry composition per soil 1 m ³ (volume%)
Content of binder: Content of blast furnace cement composition or type B blast furnace cement per 1 m ^{3 of} soil (kg)
Emissions of carbon dioxide: emissions of carbon dioxide when improving soil 1m ³ (kg). However, the value calculated from the amount of Portland cement used excluding the amount of carbon dioxide emissions derived from the energy required for the production of gypsum and recycled concrete fine powder.

As is clear from Table 5, the soil cement slurry prepared in each example was used in the case of improving soil 1 m ³ as compared with Comparative Examples 18 to 21 using blast furnace cement B type that has been conventionally used. It is characterized by a small amount of carbon dioxide emission, and good flowability and flow retention with a flow value of 200 mm or more are obtained, and at the same time, a result that sufficiently satisfies the target uniaxial compression strength is obtained. .

Claims (10)

A slurry composition for ground improvement containing at least a binder, water and an admixture, wherein the mass ratio of water / the blast furnace cement composition is 40 to 250% using the following blast furnace cement composition as a binder. A slurry composition for ground improvement using a blast furnace cement composition prepared and containing 0.1 to 5 parts by mass of an admixture per 100 parts by mass of the blast furnace cement composition.
Blast furnace cement composition: 60 to 90% by mass of fine powder of blast furnace slag having a fineness of 3000 to 13000 cm ² / g, 5 to 20% by mass of gypsum, and 5 to 35% by mass of Portland cement (total 100% by mass) A blast furnace cement composition in which a reclaimed concrete fine powder having a calcium hydroxide content of 3 to 15% by mass separated from demolition concrete is added at a rate of 10 to 30 parts by mass per 100 parts by mass of the mixture.   The slurry composition for ground improvement using the blast furnace cement composition according to claim 1, wherein the gypsum is anhydrous gypsum. The slurry composition for ground improvement using the blast furnace cement composition according to claim 1 or 2, wherein the fine powder of blast furnace slag has a fineness of 3500-6500 cm ² / g.   The slurry composition for ground improvement using the blast furnace cement composition according to any one of claims 1 to 3, wherein the recycled concrete fine powder has a calcium hydroxide content of 6 to 12% by mass.   The slurry composition for ground improvement using the blast furnace cement composition according to any one of claims 1 to 4, wherein the Portland cement is ordinary Portland cement.   Contains a fluidizing agent comprising an alkali metal salt of a water-soluble vinyl copolymer having a weight average molecular weight of 2000 to 70000 obtained by alkaline hydrolysis of a copolymer of α-olefin and maleic anhydride as at least a part of the admixture. A slurry composition for ground improvement using the blast furnace cement composition according to any one of claims 1 to 5.   The blast furnace cement composition according to any one of claims 1 to 6, comprising a fluidizing agent comprising an alkali metal salt of polyacrylic acid having a mass average molecular weight of 1500 to 50000 as at least a part of the admixture. A slurry composition for ground improvement.   The slurry composition for ground improvement using the blast furnace cement composition as described in any one of Claims 1-7 containing the antifoamer which consists of polyalkylene glycol monoalkenyl ether as at least one part of an admixture.   A slurry composition for ground improvement using the blast furnace cement composition according to any one of claims 1 to 8, wherein the mass ratio of the water / blast furnace cement composition is adjusted to 45 to 230%. Process for the preparation of soil cement slurry of ground improvement slurry composition using a blast furnace cement composition of any one of the preceding of claims 1 to 9, characterized by using a ratio of 300~1200kg per soil 1 m ³ .