JP2008094668A - Grout composition and grout material using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grout composition which is easily kneaded and capable of suppressing hardening shrinkage occurring in the hardening of mortar and providing a non-shrinkage grout material to which high strength development is imparted, and to provide the grout material. <P>SOLUTION: The grout composition comprises cement, an expansive material, a water reducing agent and silica fume containing ≥97% SiO<SB>2</SB>and having pH4-7. The group composition comprises a deforming agent. The expansive agent is a calcium aluminoferrite based expansive material. The expansive material is contained by 1-4 pts. in 100 pts. binder comprising the cement, the expansive material and the silica fume. The water reducing agent is a polycarboxylate based water reducing agent. The silica fume has 5-20 m<SB>2</SB>/g BET specific surface area. The silica fume is contained by 3-20 pts. in 100 pts. binder. The grout material comprises the grout composition and water. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a grout composition used in the civil engineering and construction industry, and a grout material using the same.

  Conventionally, grout materials are generally cement-added water-reducing agents, and are further combined with an expansion material, for example, calcium sulfoaluminate-based expansion material or lime-based expansion material, as a paste or mortar. Widely used in civil engineering and construction work.

  In recent years, as the quality of concrete has become higher and higher, and the structure itself has become more complex, the performance required for grout materials has become diversified and sophisticated.

  Grout materials, especially non-shrink grout materials, including PC grout, prepacked concrete grout, tunnel and shield backfill grout, precast grout, structural repair and reinforcement infusion grout, bridge bearing grout, undertrack grout, It is used in a wide variety of areas such as grouting around seismic steel frame braces, grout for expansion of wall, grout for steel plate winding method, and grout under containment of nuclear power plant.

  In addition, for repairing cracks in concrete structures, it is necessary to use a grout material that exhibits good fillability in cracked parts with fine shapes. It is desired.

In order to impart high strength to the grout material, it is conventionally known to use a high-performance water reducing agent and silica fume (see Non-Patent Document 1).
However, the use of silica fume having a specific SiO ₂ content and pH range is not described or suggested.

In addition, a method of producing mortar / concrete having high strength by using a specific aggregate or silica fume is known (see Patent Document 1).
However, there is no description of the pH range of the silica fume used together, and it is not intended to improve fluidity.

Furthermore, a technique for producing a concrete having a compressive strength of 120 MPa or more using a water reducing agent mainly composed of a water-soluble vinyl copolymer having high water reducing performance and silica fume has been proposed (see Patent Document 2).
However, the use of silica fume having a specific SiO ₂ content and pH range is not described or suggested.

  When a cement composition having an extremely small water binder ratio as in the conventional technique is used, it is necessary to add a large amount of high-performance water reducing agent in order to ensure a predetermined fluidity. A grout material with a large amount of high-performance water reducing agent may cause a large amount of foam in the kneaded mortar or a setting delay, and if the water binder ratio is reduced, the addition of the high-performance water reducing agent Even if the amount is increased, mixing with a hand-type mixer becomes impossible, and when a pozzolan ultrafine powder such as silica fume is blended, it is difficult to ensure no-shrinkage because curing shrinkage increases.

In addition, in order to produce mortar concrete that is easy to handle during manufacturing operations and has high strength and high workability with the use of a small amount of water reducing agent, silicon dioxide (SiO ₂ ) as the main component and zirconium oxide as one component It is known to use a powder composed of fine particles containing (see Patent Document 3).
However, Patent Document 3 only shows that the particle size of the siliceous fine powder is important. In order to improve the kneadability of the mortar and prevent setting delay, the SiO ₂ content is 97% or more. There is no disclosure of the technical idea of using silica fume having a pH of 4-7.
The invention described in Patent Document 3 avoids the use of an expansion material.

Furthermore, even when the water-cement ratio is low, the fluidity is high, and the cured product has a high compressive strength at the age of 28 days of 80 N / mm ² or more, and does not cause separation of materials such as aggregates. And the invention of the mortar which can be used conveniently as a high intensity | strength non-shrinking grout mortar is further known if an expansion material is used together (refer patent document 4).
However, in Patent Document 4, there is no description about the SiO ₂ content and pH of silica fume, and in order to improve the kneadability of the mortar and prevent setting delay due to the addition of a large amount of water reducing agent, use of a specific silica fume is used. It is not shown to do.

The latest technology and application of concrete admixture, September 10, 2001, issued by CMC, P174 Japanese Patent Laid-Open No. 05-058701 Japanese Patent Laid-Open No. 06-191918 JP 2004-203733 A JP 2005-119885 A

  As a result of various investigations to solve the above problems, the present inventor obtained knowledge that the above problems can be solved by using a specific silica fume in combination with an expanding material and a water reducing agent to form a grout composition. The present invention has been completed.

  The present invention is intended to solve the problems not shown in the prior art, is easy to knead, can suppress the curing shrinkage that occurs when the mortar is cured, and has a grout imparted with high strength. It is an object of the present invention to provide a composition and a grout material using the composition.

That is, the present invention is a grout composition comprising a cement, an expanding material, a water reducing agent, and silica fume having a SiO ₂ content of 97% or more and a pH of 4 to 7, and an antifoaming agent. The grout composition comprising, the expansion material is the grout composition that is a calcium aluminoferrite-based expansion material, and the expansion material is in 100 parts of a binder composed of cement, the expansion material, and the silica fume. 1 to 4 parts of the grout composition, the water reducing agent is the grout composition of a polycarboxylate-based water reducing agent, and the silica fume has a BET specific surface area of 5 to ²⁰ m ² / g. A composition, wherein the silica fume is a grout composition of 3 to 20 parts in 100 parts of a binder, the grout composition is a grout material containing water, and water is water / The binder ratio is 15-25% Is the grout material.

  By using the grout composition of the present invention, even when the water binder ratio is low, kneading is easy, curing shrinkage that occurs when the mortar is cured can be suppressed, and further, no shrinkage imparting high strength expression Grouting materials can be provided.

The present invention will be described in detail below.
Unless otherwise specified, the parts and% used in the present invention are shown on a mass basis.
The grout material of the present invention refers to grout mortar and grout paste.

  As the cement used in the present invention, various portland cements such as normal, early strong, moderately hot, and low heat can be mentioned, and any portland cement can be used, but ensuring good fluidity and low shrinkage. From the viewpoint of properties, low heat Portland cement is more preferable. In the present invention, eco cement can also be used as cement.

  Examples of the expansion material used in the present invention include calcium sulfoaluminate-based expansion material, calcium aluminoferrite-based expansion material, lime-based expansion material, and gypsum-based expansion material, but calcium in terms of fluidity retention performance. An aluminoferrite expansion material is preferred.

Calcium aluminoferrite-based expansion material is generally blended with CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, and CaSO ₄ raw material at a predetermined ratio, using an electric furnace, rotary kiln, etc. Is manufactured by heat treatment at 1,100-1600 ° C.
If the heat treatment temperature is lower than 1,100 ° C, the obtained expansion material may not have sufficient expansion performance, and if it exceeds 1,600 ° C, anhydrous gypsum may decompose.

Examples of the CaO raw material include limestone and slaked lime, Al ₂ O ₃ raw material includes bauxite and aluminum residual ash, Fe ₂ O ₃ raw material includes copper calami and commercially available iron oxide, and CaSO ₄ raw material includes two. Examples thereof include water gypsum, hemihydrate gypsum, and anhydrous gypsum.

Calcium aluminoferrite-based expansion material is a material obtained by heat treatment of CaO raw material, Al ₂ O ₃ raw material, Fe ₂ O ₃ raw material, and CaSO ₄ raw material, and includes free lime, calcium aluminoferrite, and anhydrous gypsum. It contains expansion material.
The proportions of free lime, calcium aluminoferrite, and anhydrous gypsum are not particularly limited, but the free lime is preferably 30 to 60 parts, more preferably 15 to 35 parts, in 100 parts of the expansion material. Further, the calcium aluminoferrite is preferably 10 to 40 parts, more preferably 15 to 35 parts. The anhydrous gypsum is preferably 10 to 40 parts, more preferably 20 to 35 parts. If free lime, calcium aluminoferrite, and anhydrous gypsum are outside this range, a predetermined expansion amount may not be obtained, or the strength may decrease due to abnormal expansion.

The fineness of the expandable material is preferably 2,000 to 6,000 cm ² / g in terms of the specific surface area of the brain (hereinafter referred to as the brain value). If it is less than 2,000 cm ² / g, the amount of expansion may be too large, and if it exceeds 6,000 cm ² / g, proper expansion may not be obtained.
The amount of the expansion material used is preferably 1 to 4 parts, more preferably 1.5 to 3 parts, in 100 parts of the binder composed of cement, expansion material, and silica fume. If it is less than 1 part, it may be difficult to obtain an expandable property, and if it exceeds 4 parts, the amount of expansion becomes large, which may lead to destruction of the cemented body.

In the present invention, a water reducing agent is used in combination from the viewpoint of suppressing curing shrinkage when used in combination with an expanding material and ensuring and maintaining fluidity.
As the water reducing agent, it is possible to use one or more of polycarboxylate type water reducing agent, naphthalene sulfonate type water reducing agent, melamine sulfonate type water reducing agent, and lignin sulfonate type water reducing agent. Yes, both liquid and powder can be used. Of these, it is preferable to use a polycarboxylate-based water reducing agent since curing shrinkage is small.
The amount of the polycarboxylate-based water reducing agent used is preferably 0.05 to 0.5 part, more preferably 0.1 to 0.3 part in terms of solid content with respect to 100 parts of the binder. If it is less than 0.05 part, the fluidity may be insufficient, and if it exceeds 0.5 part, foam may be generated or a setting delay may occur.
The amount of naphthalene sulfonate-based water reducing agent or melamine sulfonate-based water reducing agent used is preferably 0.1 to 3.0 parts, more preferably 0.5 to 1.5 parts in terms of solid content, relative to 100 parts of the binder. If it is less than 0.1 part, the fluidity may be insufficient. If it exceeds 3.0 part, bubbles may be generated or a setting delay may occur.
When two or more water reducing agents are used in combination, it is possible to use one of the water reducing agents in a range less than the above preferred range.

In the present invention, silica fume having a SiO ₂ content of 97% or more and a pH of 4 to 7 is used.
Silica fume is an ultrafine particle having an average particle diameter of 1 μm or less mainly composed of amorphous SiO ₂ , and the silica fume used in the present invention (hereinafter referred to as the present silica fume) has a SiO ₂ content of 97% or more, If pH is 4-7, it will not specifically limit. For example, as the present silica fume, it is possible to use dust collected when a spherical silica is produced or an optical fiber is produced, for example, collected by a dust collector or the like.
If the SiO ₂ content of silica fume is less than 97%, the amount of water reducing agent to obtain the prescribed fluidity will increase, causing a large amount of foam on the mortar surface, causing a delay in setting, and causing insufficient strength. , The load during mixing may become too large.
In addition, when the pH of the silica fume is less than 4, if the silica fume is stored in an iron tank for a long period of time, it may rust on the iron surface. If the pH is on the alkaline side, the water is reduced to obtain a predetermined fluidity. In some cases, the amount of the agent used may increase, causing a delay in setting, or the load during mixing may become excessive.

  Here, the pH is the pH of a mixture in which silica fume is suspended in water. For example, 2 g of silica fume is added to 98 g of pure water, stirred for 5 minutes with a magnetic stirrer, and then hydrogen ions in the suspension. The concentration is a value measured with a pH meter.

The present invention, BET specific surface area of silica fume preferably ^{5~20m 2 / g, 5~15m 2 /} g is more preferable. If it is less than 5 m ² / g, it may be difficult to obtain an effect of strength enhancement, and if it exceeds 20 m ² / g, fluidity may not be obtained.

  The amount of silica fume used is preferably 3 to 20 parts, more preferably 5 to 15 parts, in 100 parts of the binder. If it is less than 3 parts, strength development is insufficient, the ball bearing effect is lost, and the load during mixing may become too large to mix, and if it exceeds 20 parts, sufficient strength cannot be obtained. There is a case.

In the present invention, it is preferable to use an antifoaming agent in order to defoam the air of the knitted grout material and increase the strength.
Although an antifoamer is not specifically limited, A polyoxyethylene alkyl ether type | system | group antifoamer, a pluronic type antifoamer, etc. are mentioned.
The amount of the antifoaming agent used is preferably 0.005 to 0.05 part with respect to 100 parts of the binder. If it is less than 0.005 parts, the defoaming effect is insufficient, the entrapped air and the water reducing agent Entrend air may not be able to escape, and the strength may be insufficient. If it exceeds 0.05 parts, it is defoamed (defoamed) A large amount of bubbles may come to the surface of the grout material, and integration with the upper part may be insufficient.

  In the present invention, the amount of water with which each material of the grout composition is kneaded is preferably from 15 to 25%, more preferably from 16 to 20% in terms of water / binder ratio. Outside this range, fluidity may be greatly reduced or strength may be reduced.

In the present invention, a thickener can be used in combination.
Examples of the thickener include polyvinyl alcohol thickeners, acrylic thickeners, and water-soluble cellulose thickeners.
The amount of thickener used is preferably 0.1 parts or less with respect to 100 parts of the binder. If it exceeds 0.1 parts, the workability may be inferior due to excessive thickening.

  Moreover, in this invention, it is possible to use together oxycarboxylic acid or its salt, saccharides, such as dextrin and sucrose, and what has delay property, such as inorganic salt.

  In the present invention, one or more fine aggregates, rust inhibitors, antifreeze agents, shrinkage reducing agents, gas foaming substances, polymers, and the like may be used as long as the object of the present invention is not substantially impaired. It is possible to use.

  In the grout composition of the present invention, the mixing method of each material is not particularly limited, and each material may be mixed at the time of construction, or a part or all of them may be mixed in advance. Absent.

  As the mixing apparatus, any existing apparatus such as a tilting cylinder mixer, an omni mixer, a Henschel mixer, a V-type mixer, and a Nauta mixer can be used.

  Also, the method for kneading the grout material of the present invention is not particularly limited, and general-purpose mixers such as hand mixers, pan-type mixers, and biaxial mixers can be used.

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

Experimental example 1
0.16 parts of water reducing agent A in terms of solid content and silica fume (SF) shown in Table 1 with respect to 87 parts of cement, α3 parts of expansion material, and 100 parts of binder consisting of cement, expansion material, and silica fume (SF) ) 10 parts were mixed to prepare a grout composition, water was added so that the water / binder ratio was 18%, and kneaded for 180 seconds using a high-speed hand mixer to prepare a grout material.
The kneadability and fluidity during kneading of the prepared grout material were evaluated, and the setting time and compressive strength were measured. The results are also shown in Table 1.

<Materials used>
Cement: Low heat Portland cement, commercial product expansion material α: calcium aluminoferrite-based expansion material, brane value 3,000 cm ² / g, commercial product SF i: SiO ₂ content 92.7%, pH 4.2, BET specific surface area 9.22 m ² / g
SFro: SiO ₂ content 99.7%, pH 4.5, BET specific surface area 45.24m ² / g
SF Ha: SiO ₂ content 99.9%, pH 5.8, BET specific surface area 5.60m ² / g
SF d: SiO ₂ content 99.9%, pH 6.5, BET specific surface area 13.45m ² / g
SF Ho: SiO ₂ content 99.9%, pH 7.0, BET specific surface area 18.32m ² / g
SF: SiO ₂ content 99.9%, pH 6.0, BET specific surface area 3.90m ² / g
SF: SiO ₂ content 97.1%, pH 4.4, BET specific surface area 9.95m ² / g
SF h: SiO ₂ content 96.3%, pH 7.7, BET specific surface area 19.32 m ² / g
Water reducing agent A: Polycarboxylate water reducing agent, commercially available product

<Measurement method>
Kneading property: Kneading resistance for 60 seconds after starting kneading with a hand mixer was evaluated in four stages. Judgment criteria were not possible when kneading was impossible, kneading was possible, but extremely heavy was acceptable, heavy was good, and mixing was easy.
Flowability: Spreading time after filling the cement paste container of JIS R 5201-1997 “Physical testing method of cement” and lifting the container: JIS A 6204-2000 Chemical admixture for concrete Annex 1 (normative) ) Final time compressive strength measured by concrete setting time test method: Measured at age 28 days of sealing curing according to JSCE-G 505-1999 “Compressive strength test method of mortar or cement paste using cylindrical specimen” Foam state: Visual determination of the state of the grout material surface after completion of the kneading. When all the bubbles disappeared, it was judged to be good.

From Table 1, it can be seen that when SF ₂ having a SiO ₂ content of 97% or more and pH of 4 to 7 is blended, good kneadability is possible and good fluidity is obtained. On the other hand, when silica fume outside the range is used, it turns out that kneading is impossible.

Experimental example 2
It was carried out in the same manner as in Experimental Example 1 except that 0.16 parts of water reducing agent A in terms of solid content and cement and SF C shown in Table 2 were used with respect to 3 parts of the expansion material and 100 parts of the binder. The results are also shown in Table 2.

  From Table 2, it can be seen that when 3 to 20 parts of SF is blended, good kneadability is possible and sufficient compression strength is exhibited.

Experimental example 3
A grout material was prepared by blending 10 parts of SF Ha and cement, an expanding material, and a water reducing agent as shown in Table 3, and kneadability, fluidity, setting time, compressive strength, and length change rate were measured. Except that, the same procedure as in Experimental Example 1 was performed. The results are also shown in Table 3.

<Materials used>
Expansion material β: calcium sulfoaluminate-based expansion material, brane 2,800 cm ² / g, commercial product expansion material γ: lime-based expansion material, brane 3,500 cm ² / g, commercial product water reducing agent B: naphthalene sulfonate-based water reduction Agent, commercial product

<Measurement method>
Length change rate: Measured according to JIS A6202, “Expandable material for concrete, Annex 1 (normative) Expansive property test of expanded material with mortar”. Curing is 20 ℃ sealed curing, measurement material age 1 day, 7 days

  From Table 3, it can be seen that within the range of the present invention, the fluidity retention performance is good, there is no setting delay, the compressive strength is sufficient, and there is no or little cure shrinkage. In particular, it is preferable to use a calcium aluminoferrite-based expanding material as the expanding material and a polycarboxylate-based water reducing agent as the water reducing agent, since the fluidity retention performance is good and there is no curing shrinkage.

Experimental Example 4
Mix 87 parts of cement, 3 parts of expansive material α, 10 parts of SF, and water reducing agent A and antifoaming agent shown in Table 4 to produce a grout material with the water / binder ratio (W / G) shown in Table 4. The test was carried out in the same manner as in Experimental Example 1 except that the kneadability, foam state, fluidity, setting time, compressive strength, and length change rate were measured and the foam state was evaluated. The results are also shown in Table 4.

<Materials used>
Antifoaming agent: Polyoxyethylene alkyl ether antifoaming agent, commercial product

  It can be seen from Table 4 that when W / G is in the range of 15 to 25%, kneading is possible, there is no setting delay, sufficient compression strength is exhibited, and there is no cure shrinkage. Furthermore, it turns out that the further high intensity | strength expression can be expected by using an antifoamer.

  The grout material of the present invention includes PC grout, prepacked concrete grout, tunnel and shield backfill grout, precast grout, structure repair and reinforcement injection grout, bridge support grout, under-track grout, around seismic steel brace It can be widely used for civil engineering and construction applications such as frame grout, extension wall back-out grout, steel sheet winding grout, and nuclear power plant containment grout.

Claims (10)

A grout composition comprising cement, an expanding material, a water reducing agent, and silica fume having a SiO ₂ content of 97% or more and a pH of 4 to 7.   The grout composition according to claim 1, further comprising an antifoaming agent.   The grout composition according to claim 1 or 2, wherein the expansion material is a calcium aluminoferrite-based expansion material.   The grout composition according to any one of claims 1 to 3, wherein the expansion material is 1 to 4 parts in 100 parts of a binder composed of cement, an expansion material, and the silica fume.   The grout composition according to any one of claims 1 to 4, wherein the water reducing agent is a polycarboxylate-based water reducing agent. The grout composition according to any one of claims 1 to 5, wherein the silica fume has a BET specific surface area of 5 to ²⁰ m ² / g.   The grout composition according to any one of claims 1 to 6, wherein the silica fume is 3 to 20 parts in 100 parts of the binder.   A grout material using the grout composition according to any one of claims 1 to 7.   A grout material comprising the grout composition according to any one of claims 1 to 7 and water.   The grout material of claim 9, wherein the water is 15-25% in water / binder ratio.