JP5271073B2 - Hardened concrete and concrete composition - Google Patents

Description

  The present invention relates to a hardened concrete body and a concrete composition, and more particularly to a concrete hardened body in which shrinkage is suppressed and a concrete composition for producing the hardened body.

A hydraulic composition such as cement hardens with its hydration reaction, and the hardened concrete shrinks due to self-shrinkage, drying shrinkage, or the like, thereby generating shrinkage strain. In particular, a calcium sulfoaluminate (3CaO.3Al ₂ O ₃ .CaSO ₄ ) -based hydraulic composition has a property of being rapidly cured by a hydration reaction. The strain becomes larger.

  If shrinkage strain occurs in the hardened concrete, it can cause cracks. The generated crack not only impairs the aesthetics of the hardened concrete, but also causes corrosion of the steel in the hardened concrete, lowering the water tightness of the hardened concrete, and reducing the strength of the hardened concrete. . In order to suppress the shrinkage strain of such a hardened concrete, conventionally, a concrete to which a shrinkage reducing agent or an expansion material is added has been proposed.

  A concrete hardened body cured by adding an expansion material to a hydraulic composition such as cement that rapidly hardens has not been sufficiently effective in reducing the amount of strain due to shrinkage of the hardened body. Therefore, the shrinkage cannot be completely suppressed, and there is still a problem that cracks still occur in the concrete. In addition, the hardened concrete cured by adding a shrinkage reducing agent to the hydraulic composition is expensive, and the production of the hardened concrete is costly and completely suppresses shrinkage. There was a problem that we couldn't.

  In view of such circumstances, the present invention has high strength with rapid onset of strength, and can reduce shrinkage strain due to self-shrinkage and drying shrinkage, etc. It aims at providing the concrete composition which can manufacture the concrete hardened | cured material which can be prevented, and the said concrete hardened | cured material.

In order to solve the above problems, the present invention provides a calcium sulfoaluminate composition 100 containing 3 to 60% by weight of calcium sulfoaluminate (3CaO.3Al ₂ O ₃ .CaSO ₄ ) and 1 to 40% by weight of anhydrous gypsum. relative to the weight section, a hydraulic composition specific surface comprises 0.1 to 3.0 parts by weight of lithium carbonate _{^{1000~4000cm 2 / g, 3CaO · SiO}} 2 -2CaO · SiO 2 -CaO- gap material system composition, 3CaO _· SiO 2 -CaO- gap material based composition, 2CaO _· SiO 2 -CaO- gap material based composition, and CaO- gap material systems one or more selected from the group consisting of composition A clinker composition containing the composition and having a CaO content of 50 to 92% by mass, and a compound containing an expandable admixture containing gypsum is cured. Providing concrete hardened body, characterized in bets (invention 1).

The said concrete hardening body can express intensity | strength at an early stage with the calcium sulfoaluminate in a hydraulic composition, and can reduce a shrinkage | contraction strain amount with a lithium carbonate whose specific surface area is 1000-4000 cm < ² > / g. it can. In addition, ettringite (3CaO · Al ₂ O ₃ · 3CaSO ₄ · 32H ₂ O) is obtained by a reaction between gypsum (CaSO ₄ ) and calcium aluminate (particularly tricalcium aluminate (C ₃ A)) in the expandable admixture. ), And the shrinkage of the hardened concrete can be suppressed by the ettringite. Therefore, according to the said invention (invention 1), shrinkage | contractions, such as self shrinkage and drying shrinkage | contraction, can be suppressed and generation | occurrence | production of the crack by shrinkage | contraction distortion can be prevented.

Here, in the present invention, “3CaO · SiO ₂ −2CaO · SiO ₂ —CaO—interstitial material composition” means 0.5% by mass or more of alite (3CaO · SiO ₂ ) and 0.5% by mass. It refers to a composition containing the above belite (2CaO · SiO ₂ ), a CaO crystal, and a gap substance.

In the present invention, the “3CaO · SiO ₂ —CaO—interstitial material composition” includes 0.5% by mass or more of alite (3CaO · SiO ₂ ), CaO crystal, and interstitial material, This refers to a composition having a belite (2CaO.SiO ₂ ) content of less than 0.5% by mass.

Furthermore, in the present invention, “2CaO · SiO ₂ —CaO—interstitial material composition” includes 0.5% by mass or more of belite (2CaO · SiO ₂ ), CaO crystals, and interstitial materials, This refers to a composition having an alite (3CaO.SiO ₂ ) content of less than 0.5% by mass.

Furthermore, the "CaO- gap material based composition" in the present invention contains a CaO crystal and the gap material, alite (3CaO · SiO ₂₎ and belite (2CaO · SiO ₂₎ content of both It means less than 0.5% by weight.

  In the said invention (invention 1), it is preferable that the said expansive admixture contains 5-50 mass parts of said gypsum with respect to 100 mass parts of said clinker compositions (invention 2).

According to the above invention (Invention 2), Within the above range, the amount of gypsum in the expandable admixture, by the generated ettringite _{(3CaO · Al 2 O 3 ·} 3CaSO 4 · 32H 2 O), concrete curing Body contraction can be effectively suppressed.

  In the said invention (invention 1), it is preferable that the said expansive admixture further contains quicklime (invention 3). According to this invention (invention 3), quick lime contained in the expandable admixture expands with the hydration reaction, so that the shrinkage of the hardened concrete can be further suppressed.

  In the said invention (invention 3), the said expandable admixture contains 20 mass parts or more of the said clinker composition in the total 100 mass parts of the said clinker composition and the said quicklime, The said clinker composition and the said It is preferable that 5-50 mass parts of said gypsum is included with respect to a total of 100 mass parts with quicklime (invention 4).

  If it is the mixture ratio in the said invention (invention 4), a concrete hardened | cured material will not expand too much, the shrinkage | contraction of a concrete hardened | cured material can be suppressed effectively, and the crack by shrinkage | contraction distortion can be prevented.

In the above invention (invention 1 to 4), wherein the expandable admixture in the concrete cured body 1 m ³ it is preferable to blend the expandable admixture to include 10～40Kg (invention 5). If it is the blending amount according to the above invention (Invention 5), the shrinkage of the hardened concrete can be effectively suppressed without impairing the early strength development of concrete, and the occurrence of cracks due to shrinkage strain can be prevented. it can.

  In the said invention (invention 1-5), the said mixture is 0.05-1.5 mass parts tartaric acid in conversion of tartaric acid with respect to a total of 100 mass parts of the said hydraulic composition and an expansive admixture. Or it is preferable to further contain 0.05-1.5 mass parts heptonic acid or its salt in conversion of the salt and / or heptonic acid (invention 6).

  In the said invention (invention 1-6), the said compound is 0.01-0.3 mass part in conversion of boric acid with respect to a total of 100 mass parts of the said hydraulic composition and an expansive admixture. It is preferable to further contain boric acid or a salt thereof (Invention 7).

Further, the present invention relates to 100 parts by mass of a calcium sulfoaluminate composition containing 3 to 60% by mass of calcium sulfoaluminate (3CaO.3Al ₂ O ₃ .CaSO ₄ ) and 1 to 40% by mass of anhydrous gypsum. A hydraulic composition containing 0.1 to 3.0 parts by mass of lithium carbonate having a specific surface area of 1000 to 4000 cm ² / g, a 3CaO · SiO ₂ −2CaO · SiO ₂ —CaO—interstitial material composition, and 3CaO · SiO ₂ -CaO- gap material based composition comprises 2CaO _· SiO 2 -CaO- gap material based composition, and CaO-1 kind selected from the group consisting of interstitial material based composition or two or more compositions, and A concrete composition comprising: a clinker composition having a CaO content of 50 to 92% by mass; and an expansive admixture containing gypsum. (Invention 8).

  According to the above invention (Invention 8), by curing such a concrete composition, it is possible to produce a hardened concrete body that has high strength while generating rapid strength and does not cause shrinkage strain. it can.

  In the said invention (invention 8), it is preferable that the said expansive admixture contains 5-50 mass parts of said gypsum with respect to 100 mass parts of said clinker compositions (invention 9). Moreover, in the said invention (invention 8), it is preferable that the said expansive admixture further contains quicklime (invention 10). Furthermore, in the said invention (invention 10), the said expandable admixture contains 20 mass parts or more of the said clinker composition in 100 mass parts in total of the said clinker composition and the said quicklime, The said clinker composition It is preferable that 5-50 mass parts of said gypsum is included with respect to 100 mass parts in total with said quicklime (invention 11).

In the above invention (Claim 8 to 11), said expandable admixture to the concrete composition concrete during the curing body 1 m ³ obtained by curing the to blend the expandable admixture to include 10~40kg (Claim 12).

  In the said invention (invention 8-12), 0.05-1.5 mass parts tartaric acid or its salt in conversion of tartaric acid with respect to a total of 100 mass parts of the said hydraulic composition and an expansive admixture, and / or Or it is preferable that 0.05-1.5 mass parts heptonic acid or its salt is further included in conversion of heptonic acid (invention 13).

  Mixing the hydraulic composition and the expansive admixture, adding citric acid, which is generally used as a setting retarder, and then adding water and kneading, the concrete composition quickly sets, and is sufficient There is a risk that it will not be possible to ensure a long pot life (time from discharging the concrete from the mixer to the start of setting of the concrete). Then, by adding citric acid as a setting retarder to the hydraulic composition, adding water and kneading, and finally adding the expandable admixture, the time until the concrete composition rapidly sets, that is, The pot life can be extended, but it may be difficult to mix the expandable admixture uniformly in the hardened concrete. However, tartaric acid or a salt thereof or heptonic acid or a salt thereof is mixed with the hydraulic composition and the expansive admixture, and even if water is added and kneaded, the concrete composition does not rapidly set, Therefore, according to the said invention (invention 13), the pot life of concrete can be ensured enough and workability can be made favorable.

  In the said invention (invention 8-13), 0.01-0.3 mass part boric acid or its salt in conversion of boric acid with respect to a total of 100 mass parts of the said hydraulic composition and an expansive admixture. (Invention 14)

  According to the said invention (invention 14), since the concrete composition contains boric acid or a salt thereof, the heat of hydration of the concrete composition can be reduced, and the concrete kneading temperature (CT; Concrete) Temperature) can be reduced. Thereby, even in a high temperature environment where the outside air temperature exceeds 30 ° C., the concrete can be easily shipped and constructed.

  According to the hardened concrete body of the present invention, the strength of the hardened concrete body can be expressed rapidly, and shrinkage such as self-shrinkage and drying shrinkage can be greatly suppressed, and the occurrence of cracks and the like due to shrinkage strain can be prevented. Can be prevented. Moreover, according to the concrete composition of this invention, the concrete hardening body which can prevent generation | occurrence | production of the crack by shrinkage | contraction distortion, etc. can be manufactured.

It is a graph which shows the relationship between the age of the hardened concrete body of Example 1, and the amount of strain. It is a graph which shows the relationship between the boric acid addition rate of concrete composition in the external temperature of 5 degreeC, and concrete kneading temperature. It is a graph which shows the relationship between the boric-acid addition rate of concrete composition in the external temperature of 35 degreeC, and concrete kneading temperature.

Hereinafter, the concrete composition and the concrete hardened body of the present invention will be described.
The concrete composition of the present invention includes a hydraulic composition and an expandable admixture. The hydraulic composition includes a calcium sulfoaluminate composition and lithium carbonate. The calcium sulfoaluminate composition contains 3 to 60% by mass of calcium sulfoaluminate (3CaO.3Al ₂ O ₃ .CaSO ₄ ) and 1 to 40% by mass of anhydrous gypsum, and 20 to 20% of calcium sulfoaluminate. It is preferable to contain 40% by mass and 5 to 15% by mass of anhydrous gypsum.

  The blending amount of lithium carbonate in the hydraulic composition is 0.1 to 3.0 parts by mass and 0.5 to 1.5 parts by mass with respect to 100 parts by mass of the calcium sulfoaluminate composition. preferable. When the blending amount of lithium carbonate in the hydraulic composition is less than 0.1 parts by mass, the initial strength of the hardened concrete is not sufficiently expressed, and when it exceeds 3.0 parts by weight, the shrinkage strain of the hardened concrete is reduced. Although there is no big change in the reduction effect, the production of the hardened concrete is costly.

The specific surface area (Blaine specific surface area) of lithium carbonate contained in the hydraulic composition is 1000 to 4000 cm ² / g, preferably 2000 to 3000 cm ² / g. When the specific surface area is less than 1000 cm ² / g, the lithium carbonate particles are coarse, and when mixed with the calcium sulfoaluminate composition or when kneaded into concrete, the lithium carbonate is difficult to uniformly disperse, and the hardened concrete body This will cause a decrease in strength. On the other hand, if the specific surface area exceeds 4000 cm ² / g, an effect sufficient for reducing shrinkage strain cannot be obtained.

The method for adjusting the specific surface area of lithium carbonate is not particularly limited. For example, the lithium carbonate ore used as a raw material can be pulverized so as to have a specific surface area of 1000 to 4000 cm ² / g. As a method for pulverizing the lithium carbonate ore, for example, any pulverization method such as a method using a ball mill or a free pulverizer can be applied.

The expandable admixture includes a clinker composition and gypsum, and preferably further includes quicklime. The clinker _{composition, 3CaO · SiO 2 -2CaO · SiO} 2 -CaO- gap material based composition, 3CaO _· SiO 2 -CaO- gap material based composition, 2CaO _· SiO 2 -CaO- gap material based composition, And one or more selected from the group consisting of CaO-interstitial material-based compositions, and the CaO content is 50 to 92% by mass. By including such an expandable admixture in the concrete composition, the shrinkage strain at the initial hydration of the obtained hardened concrete can be reduced, and the occurrence of cracks due to the shrinkage strain can be prevented.

Gap substances contained in the clinker composition in expandable admixture is one similar to the mineral filling between the cement clinker minerals in alite (3CaO · SiO ₂₎ and belite (2CaO · SiO _2). Such gap material, for example, calcium ferrite minerals such as 2CaO · _Fe 2 _{O 3;} calcium aluminate minerals such as _{3CaO · Al 2 O 3; 6CaO} · Al 2 O 3 · Fe 2 O 3, 4CaO · Al _{2 O 3 · Fe 2 O 3} , calcium such as _{6CaO · 2Al 2 O 3 · Fe} 2 O 3 alumino ferrite minerals, and the like.

  The content rate of CaO in a clinker composition is 50-92 mass% with respect to the total mass of a clinker composition. If the CaO content is less than 50% by mass, it may be difficult to develop strength at an early stage. If the CaO content exceeds 92% by mass, the content of interstitial materials will be relatively reduced, and the hardened concrete body. There is a risk that it will be difficult to suppress the shrinkage of the resin.

The clinker composition may contain alite (3CaO · SiO ₂ ) or belite (2CaO · SiO ₂ ), or may not contain these alite or belite, The clinker composition containing these alite and belite can significantly suppress the hydration rate of CaO, and the hydrate of these alite and belite contributes to the development of cement strength.

  The clinker composition is prepared by mixing raw materials such as calcareous raw material, clay raw material, silica stone, slags, gypsum and the like so as to have the above composition, and preparing the raw material mixture until the target clinker mineral composition is obtained. It can be obtained by baking the mixture sufficiently at a temperature of 1300 to 1600 ° C. in a rotary kiln or the like.

In addition, when baking a raw material mixture, you may add a mineralizer (flux) to a raw material mixture. Thereby, the manufacturing efficiency of a clinker composition can be improved. As a mineralizer, what is generally used when a cementitious compound is fired can be used. Specifically, gypsum, fluorite, serpentinite and the like containing compounds such as CaSO ₄ , CaF ₂ , Fe ₂ O, MgO, and Al ₂ O ₃ can be used as mineralizers. The addition amount of these mineralizers should just be about 10 mass% or less with respect to the mass of a raw material mixture.

The expandable admixture includes gypsum together with the clinker composition. By containing gypsum in the expandable admixture, ettringite (3CaO · Al ₂ O ₃ · 3CaSO ₄ · 32H ₂ O) is generated, which can suppress shrinkage of the hardened concrete, and concrete. The initial strength (demolding strength during simple steam curing) of the cured body can be increased.

  As the gypsum, commercially available gypsum can be used. Gypsum is classified into anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum according to its crystal form, and any gypsum may be used, and anhydrous gypsum can be preferably used.

  The amount of gypsum in the expandable admixture is preferably 5 to 50 parts by mass with respect to 100 parts by mass of the clinker composition. When quick lime is contained in the expandable admixture, the blending amount of gypsum is preferably 5 to 50 parts by mass with respect to 100 parts by mass as the total amount of the clinker composition and quick lime. If the blending amount of the gypsum is less than 5 parts by mass, it is difficult to suppress the shrinkage of the hardened concrete, and there is a possibility that the strength will not be developed at an early stage. There is a risk of cracking.

  The expandable admixture preferably further contains quick lime. Quick lime expands and generates heat due to the hydration reaction, so it can further suppress the shrinkage of the hardened concrete, and the calorific value of the entire expandable admixture increases, further improving the early strength development of the hardened concrete. Can be made.

  Quick lime is classified into extremely soft calcined quick lime, soft calcined quick lime, medium calcined quick lime, hard calcined quick lime, and extremely hard calcined quick lime, and the evaluation method is generally a coarse-grain titration test method using 4N hydrochloric acid of the Japan Lime Association. Is used. According to this coarse-grain titration test method, quick lime is classified based on the total amount of 4N hydrochloric acid used for the titration, extremely soft calcined quick lime has a usage amount of 4N hydrochloric acid of 800 mL or more, and soft calcined quick lime is composed of 4N hydrochloric acid. The amount used is 650 mL or more and less than 800 mL, the medium-burnt quicklime is one whose 4N hydrochloric acid is used in an amount of 300 mL or more and less than 650 mL, and the hard-burned quicklime is one whose 4N hydrochloric acid is used in an amount of 130 mL or more and less than 300 mL, Extremely hard calcined quicklime has a usage amount of 4N hydrochloric acid of less than 130 mL.

  The quicklime that can be included in the expansive admixture may be quicklime that is generally commercially available, but among the quicklime that is classified as described above, use quicklime whose amount of 4N hydrochloric acid is 650 mL or less. In particular, it is preferable to use quick lime in which the amount of 4N hydrochloric acid used is 400 mL or less. By including such quicklime, the workability of fresh concrete can be improved.

  When quick lime is included in the expandable admixture, the content of quick lime is preferably 80% by mass or less of the total mass of the clinker composition and quick lime. If the content of quicklime exceeds 80% by mass of the total mass of the clinker composition and quicklime, the amount of expansion of the hardened concrete body due to the hydration reaction may increase excessively.

  The expandable admixture contains the above clinker composition and gypsum, preferably further contains quicklime, and is preferably a mixed pulverized product obtained by pulverizing these mixtures. The mixed pulverized product may be obtained by pulverizing each of the clinker composition, gypsum, and quicklime, or may be pulverized after mixing the clinker composition, gypsum, and quicklime. The pulverization can be performed using a pulverizer used for pulverizing ordinary cement such as a ball mill and a roll mill.

Blaine specific surface area of the ground mixture obtained in this way is preferably 2000~6000cm ² / g, it is particularly preferably 4000~5000cm ² / g.

In the concrete composition, the expansive admixture is preferably blended in an amount of 10 to 40 kg in 1 m ^{3 of a} hardened concrete body obtained by curing the concrete composition, and 20 to ³⁰ kg in 1 m ^{3 of the} hardened concrete body. It is more preferable to mix the occupied amount. If it is less than 10 kg, the shrinkage strain of the concrete cured body obtained by curing the concrete composition cannot be reduced, and cracks may occur in the concrete cured body. If it exceeds 40 kg, the concrete cured body is excessively large. There exists a possibility that it may expand | swell and the intensity | strength of the said concrete hardening body may fall.

  The concrete composition of the present invention is 0.05 to 1.5 parts by mass of tartaric acid or a salt thereof and / or heptone in terms of tartaric acid with respect to a total of 100 parts by mass of the hydraulic composition and the expandable admixture. It is preferable to further contain 0.05 to 1.5 parts by mass of heptonic acid or a salt thereof in terms of acid. When the concrete composition of the present invention is cured to produce a hardened concrete body, the hydraulic composition and the expandable admixture may be mixed in advance and kneaded with water, or the water Water may be added to the hard composition and kneaded, and then the expandable admixture may be added and further kneaded. In the production of hardened concrete, one containing citric acid is generally used as a setting retarder, but when citric acid is added in the former case, ettringite accompanying the hydration reaction of the hydraulic composition and the expandable admixture is used. As a result of the rapid generation of, the concrete composition is rapidly bonded, and there is a possibility that sufficient pot life cannot be secured. In order to extend the pot life while using citric acid as a setting retarder, it is preferable to knead as in the latter case, but in this case, the expandable admixture should be mixed uniformly into the hardened concrete. May become difficult. Therefore, it is preferable to add tartaric acid (tartrate) and / or heptonic acid (heptonate) without adding citric acid. Tartaric acid (tartrate) or heptonic acid (heptonic acid salt) has a setting retarding action similar to citric acid. Even if (heptonic acid salt) is mixed in advance and water is added thereafter, rapid formation of ettringite does not occur, so that rapid setting of the concrete composition can be prevented. Thereby, while being able to ensure sufficient pot life, since an expandable admixture can be uniformly mixed with hardened concrete, it can control shrinkage distortion of hardened concrete more effectively. .

  When the blending amount of tartaric acid (tartrate) or heptonic acid (heptonic acid salt) with respect to a total of 100 parts by mass of the hydraulic composition and the expandable admixture is less than 0.05 parts by mass in terms of tartaric acid or heptonic acid The pot life of the concrete composition may not be sufficiently secured, and if it exceeds 1.5 parts by mass, not only the pot life will be greatly extended but also the setting of the concrete will be caused. There is a risk that the strength may not be sufficiently developed or may not be cured in some cases.

  The blending amount of tartaric acid (tartrate) is more preferably 0.15 to 1.2 parts by mass with respect to 100 parts by mass in total of the hydraulic composition and the expandable admixture, and 0.2 to 1.0 part by mass is particularly preferable. The blending amount of heptonic acid (heptonic acid salt) is more preferably 0.2 to 1.2 parts by mass with respect to 100 parts by mass in total of the hydraulic composition and the expandable admixture. It is especially preferable that it is 0.25-1.0 mass part.

  Examples of tartrate include, but are not limited to, ammonium tartrate, potassium tartrate, sodium tartrate, lithium tartrate, sodium sodium tartrate, potassium sodium tartrate, and the like.

  Examples of the heptonic acid salt include, but are not limited to, sodium heptonic acid, potassium heptonic acid, lithium heptonic acid and the like.

  The concrete composition of the present invention contains 0.01 to 0.3 parts by mass of boric acid or a salt thereof in terms of boric acid with respect to a total of 100 parts by mass of the hydraulic composition and the expandable admixture. It may be. By containing boric acid in the concrete composition within the above range, the heat of hydration when the concrete composition is cured can be reduced, and the concrete kneading temperature can be lowered. In particular, JASS5 (Architectural Institute of Japan, Building Construction Standard Specification 5) stipulates that the concrete placement temperature should not exceed 35 ° C. Even if it is performed, the concrete kneading temperature (CT) can be lowered, so that the concrete can be easily shipped and installed even in a high temperature environment.

  When the blending amount of boric acid (borate) is less than 0.01 parts by mass in terms of boric acid with respect to 100 parts by mass in total of the hydraulic composition and the expandable admixture, the concrete composition is cured. There is a possibility that the heat of hydration during the treatment cannot be effectively reduced. When the amount exceeds 0.3 parts by mass in terms of boric acid, there is no difference in the effect of reducing the heat of hydration. As the amount of the acid salt) increases, the cost increases, and the strength of the hardened concrete may decrease, or the setting delay may occur.

  The compounding amount of boric acid (borate) is more preferably 0.05 to 0.2 parts by mass, particularly preferably 100 parts by mass in total of the hydraulic composition and the expandable admixture. Is 0.1 to 0.15 parts by mass.

  Examples of borates include, but are not limited to, sodium borate, ammonium borate, potassium borate, lithium borate, and aluminum borate.

  The concrete composition may further contain coarse aggregate. As the coarse aggregate, for example, gravel, crushed stone, or a mixture thereof can be used. The particle size of the coarse aggregate in the concrete composition is preferably 5 to 25 mm. The blending amount of the coarse aggregate in the concrete composition is 100 in total from the hydraulic composition and the expandable admixture from the viewpoint of mechanical strength after hardening of the concrete hardened body and workability (fluidity) of fresh concrete. It is preferable that it is 0-500 mass parts with respect to a mass part, and it is more preferable that it is 100-200 mass parts.

  The concrete composition may further contain fine aggregate. As the fine aggregate, for example, river sand, land sand, sea sand, crushed sand, silica sand, or a mixture thereof can be used. The particle size of the fine aggregate is preferably 5 mm or less. The blending amount of fine aggregate in the concrete composition is preferably 0 to 500 parts by mass, and 100 to 200 parts by mass with respect to 100 parts by mass in total of the hydraulic composition and the expandable admixture. Is more preferable.

  The fine aggregate ratio in concrete compositions (the ratio of fine aggregate volume to the total aggregate (coarse aggregate and fine aggregate) volume) is 0 to 100%, such as workability of concrete composition From the viewpoint, it is preferably 30 to 70%.

The concrete composition of the present invention may contain components other than the hydraulic composition and the expandable admixture as long as the effect of reducing the shrinkage strain of the hardened concrete is not hindered. Concrete composition, for example, alite (3CaO · _SiO 2), belite Portland cement clinker containing (2CaO · SiO ₂₎ or the like; lignin, naphthalene sulfonic acid, melamine, a polycarboxylic acid-based, such as the water-reducing agent AE water reducing agent, high performance water reducing agent, high performance AE water reducing agent, etc .; other additives may be included. The blending amount of the Portland cement clinker, the setting retarder or various water reducing agents in the concrete composition may be an amount that does not hinder the effect of reducing the shrinkage strain of the hardened concrete.

  By adding a predetermined amount of water to the concrete composition of the present invention and kneading, pouring the kneaded product into a mold or the like, curing by curing with heat curing, underwater curing, steam curing, autoclave curing, etc. A hardened concrete body can be produced. When producing a hardened concrete, the hydraulic composition and the expandable admixture may be mixed in advance, and then a predetermined amount of water may be added and kneaded, or a predetermined amount of the hydraulic composition may be added to the hydraulic composition. Water may be added and kneaded, and then the above expandable admixture may be added and further kneaded. However, the former is preferable because the expandable admixture is more uniformly mixed with the hardened concrete. At this time, if general citric acid is added as a setting retarder, it may not be possible to secure sufficient pot life due to rapid setting of the concrete composition. Therefore, without adding citric acid, tartaric acid (tartaric acid Salt) and / or a concrete composition further comprising heptonic acid (heptonic acid salt). Thereby, while being able to ensure sufficient pot life, an expansive admixture can be uniformly mixed with a hardened concrete body.

  In order to ensure the pot life of concrete, to develop strength at an early stage and to reduce shrinkage strain, the amount of water is preferably 25 to 65% by mass as a water binder ratio, 30 to 30%. More preferably, it is 45 mass%.

  The concrete cured body thus obtained can exhibit the desired compressive strength in 2 to 3 hours after kneading because the hydraulic composition has early strength development. Moreover, since the expansion | swelling admixture mentioned above is contained in a concrete composition, since shrinkage | contraction of a hardened concrete body can be suppressed, the crack etc. which arise by shrinkage distortion can be prevented. In particular, the concrete hardened body produced by the formulation shown in the examples described later can obtain an excellent effect that is not seen in conventional hardened concrete bodies that hardly causes shrinkage strain while being expanded by the initial hydration reaction. it can. Therefore, the hardened concrete body of the present invention can be suitably used as a thin concrete product used for road repair work or the like.

  EXAMPLES Hereinafter, although an Example and a test example demonstrate this invention further in detail, this invention is not restrict | limited at all to the following Example and test example.

[Examples 1-4, Comparative Examples 1-2]
Fine aggregate S (land sand from Omaezaki, Shizuoka Prefecture, surface dry density: 2.60 g / cm ³ , absolute dry density: 2.55 g / cm ³ , water absorption: 1.99%, unit volume mass: 1.74 kg / L, actual volume ratio: 68.0%, coarse particle ratio: 2.64, fine particle content: 1.83%) and coarse aggregate G (Iwase Prefecture Iwase No. 6 crushed stone, coarse aggregate maximum dimension: 13 mm, table Dry density: 2.65 g / cm ³ , water absorption: 1.52%, unit volume mass: 1.55 kg / L, actual volume ratio: 59.0%, coarse grain ratio: 6.30) and empty for 15 seconds Kneaded, water W and high-performance water reducing agent SP (polycarboxylic acid-based high-performance water reducing agent, trade name: Leo Build 8000, manufactured by NMB) and setting retarder JS (trade name: Jet Setter, manufactured by Onoda Chemico) And then kneaded for 15 seconds, hydraulic composition C (super fast cement, trade name: super jet cement, Degrees: 3.01g / cm ^3, was 120 seconds kneaded was charged Pacific Ocean Ltd. Cement Co., Ltd.).

After the obtained kneaded material was scraped, an expandable admixture EX (trade name: Taiheiyo N-EX, density: 3.19 g / cm ³ , manufactured by Taiheiyo Materials Co., Ltd.) was added and kneaded for 60 seconds. Obtained.
Table 1 shows the blending ratio of each raw material.

  The obtained fresh concrete was poured into a steel mold and cured in a constant temperature room at 20 ° C. until it was subjected to a strength test at a predetermined age to obtain a hardened concrete.

[Test Example 1] Slump test The fresh concrete obtained in Examples 1 to 4 and Comparative Examples 1 and 2 was subjected to a slump test based on JIS-A1101. The slump test was conducted at each stage after discharging from the mixer. The results of the slump test are shown in Table 2.

  As shown in Table 2, the fresh concrete of Examples 1 to 4 has a slump of 12.0 to 16.5 cm immediately after being discharged from the mixer, is excellent in workability, and has a pot life of about 20 to 40 minutes. It was confirmed that (time from immediately after discharging from the mixer until the slump value becomes about 5.0 cm) can be secured.

[Test Example 2] Compressive strength test The hardened concrete obtained in Example 1 was subjected to a compressive strength test based on JIS-A1108. This compressive strength test was conducted on hardened concrete bodies having a material age of 3 hours, 6 hours, 24 hours, and 7 days. The test results are shown in Table 3.

As shown in Table 3, the 3 hour old concrete hardened bodies of Examples 1 to 4 have a compressive strength of 31.3 to 36.3 N / mm ² and a good compressive strength of 7 days old. It was confirmed that the cured concrete body of the present invention is excellent in early strength development.

[Test Example 3] Self-shrinkage test and setting test The hardened concrete obtained in Example 4 and Comparative Example 2 was subjected to a self-shrinkage test and a setting test based on JIS-A1147. In the self-shrinkage test, an implantable strain gauge was embedded in a 10 × 10 × 40 (cm) test body, and the amount of change in length was measured. In addition, the measurement start time (material age 0 hours) of the amount of change in length was the initial time of the setting test. The result of the self-shrink test is shown in FIG.

  In the setting test, the initial time and the setting time are measured by the proctor penetration resistance value using a sample obtained by curing the mortar obtained by wet screening of the fresh concrete obtained in Example 4 with a screen of 5 mm. did.

  As shown in FIG. 1, the hardened concrete body of Example 4 maintained an expansion amount of about 170 to 180 μm at the age of 24 hours, and it was confirmed that the shrinkage of the hardened concrete body did not occur. Therefore, it was confirmed that the hardened concrete body of Example 4 can prevent the occurrence of cracks due to self-shrinkage strain. On the other hand, it was confirmed that the hardened concrete body of Comparative Example 2 contracted by about 230 μm at the age of 24 hours, and self-shrinkage strain was generated. Moreover, as a result of the setting test, the initial time of the hardened concrete body of Example 4 was 41 minutes, and the final time was 58 minutes.

[Examples 5-42]
Fine aggregate S (Ibaraki Prefecture Yuki production Rikusuna, Table dry density: 2.58g / cm ^3, the bone-dry density: 2.52g / cm ^3, water absorption rate: 2.30%, Jitsusekiritsu: 65.4% , Coarse particle ratio: 2.64, fine particle amount: 1.70%), water W, high-performance water reducing agent SP (polycarboxylic acid-based high-performance water reducing agent, trade name: Leo Build 8000PX ₃ , manufactured by NMB) , Citric acid (or boric acid (orthoboric acid) and tartaric acid (L-tartaric acid), tartaric acid, boric acid and heptonic acid (sodium heptonic acid) or heptonic acid), and kneaded for 15 seconds, hydraulic composition Product C (super fast hard cement, trade name: Superjet cement, density: 3.01 g / cm ³ , manufactured by Taiheiyo Cement Co., Ltd.) and expansive admixture EX (early strength expansive material, trade name: Pacific N-EX, density) : 3.19 g / cm ³ , manufactured by Taiheiyo Materials Co., Ltd. ) Was mixed in advance and kneaded for 120 seconds. Then, coarse aggregate G (Iwase Prefecture Iwase No. 6 crushed stone, coarse aggregate maximum dimension: 13 mm, surface dry density: 2.65 g / cm ³ , water absorption: 0.62%, actual volume ratio: 60.9% , Coarse grain ratio: 6.68) and kneaded for 60 seconds to obtain fresh concrete.
Table 4 shows the blending ratio of each raw material.

[Test Example 4] Slump test / concrete kneading temperature (CT) measurement The fresh concrete obtained in Examples 5 to 42 was subjected to a slump test based on JIS-A1101. The slump test was conducted at each stage after discharging from the mixer. At the same time, the concrete kneading temperature (CT) was measured for Examples 10, 13, 16 to 25, 28, 31, and 33 to 42.
The results of the slump test are shown in Table 5, and the measurement results of the concrete kneading temperature are shown in FIGS.

  As shown in Table 5, in Examples 5 to 7 containing citric acid at an outside temperature of 20 ° C., a pot life of about 20 to 25 minutes could be secured, but even if the blending ratio of citric acid was increased, It was difficult to control the pot life. Therefore, when used in an environment where the outside air temperature exceeds 30 ° C., it is considered that there is a risk of rapid setting of the concrete composition. On the other hand, in Examples 11 and 29 containing tartaric acid or heptonic acid at an external temperature of 20 ° C., a pot life of 50 minutes or more could be secured. Thus, it was confirmed that by adding tartaric acid or heptonic acid without adding citric acid, rapid setting of the concrete composition can be prevented and sufficient pot life can be secured.

  Moreover, in Examples 8-42, by adding tartaric acid or heptonic acid without adding citric acid, it is possible to ensure a pot life of about 20 minutes considered to be the minimum necessary in actual construction, It was confirmed that sufficient workability could be secured. In particular, the concrete composition is more likely to condense as the outside air temperature is higher, and the pot life varies depending on the construction conditions such as the outside air temperature. As in Examples 8 to 15 and 26 to 32, tartaric acid or heptone By controlling the addition rate of the acid, it was confirmed that the pot life of about 20 to 60 minutes can be secured under any temperature condition, and the work can be easily performed.

  Furthermore, as shown in FIG.2 and FIG.3, it was confirmed that the kneading | mixing temperature (CT) of concrete can be reduced by adding boric acid. From this, it is considered that by adding boric acid to the concrete composition, the heat of hydration of the hardened concrete can be reduced, and even under an environment where the outside air temperature exceeds 30 ° C. It was confirmed that the kneading temperature could be 35 ° C. or less, and that concrete could be shipped and constructed easily. Furthermore, it was confirmed that there is no difference in the effect of reducing hydration heat even when boric acid is added in excess of 0.15 parts by mass with respect to 100 parts by mass in total of the hydraulic composition and the expandable admixture. .

  The hardened concrete body of the present invention is useful as a thin concrete product used for road repair work and the like, and the concrete composition of the present invention is useful as a raw material for concrete for producing such a hardened concrete body. is there.

Claims (14)

The specific surface area is 1000 to 4000 cm with respect to 100 parts by mass of calcium sulfoaluminate composition containing 3 to 60% by mass of calcium sulfoaluminate (3CaO.3Al ₂ O ₃ .CaSO ₄ ) and 1 to 40% by mass of anhydrous gypsum. ^A hydraulic composition containing 0.1 to 3.0 parts by mass of ² / g lithium carbonate;
_{3CaO · SiO 2 -2CaO · SiO 2} -CaO- gap material based composition, 3CaO _· SiO 2 -CaO- gap material based composition, 2CaO _· SiO 2 -CaO- gap material based composition, and CaO gap material based composition A clinker composition containing one or more compositions selected from the group consisting of a product and having a CaO content of 50 to 92% by mass, and an expansive admixture containing gypsum A hardened concrete body characterized by being cured.   The hardened concrete according to claim 1, wherein the expandable admixture includes 5 to 50 parts by mass of the gypsum with respect to 100 parts by mass of the clinker composition.   The hardened concrete according to claim 1, wherein the expandable admixture further contains quicklime.   The expandable admixture contains 20 parts by mass or more of the clinker composition in a total of 100 parts by mass of the clinker composition and the quicklime, and the total of 100 parts by mass of the clinker composition and the quicklime. The hardened concrete body according to claim 3, further comprising 5 to 50 parts by mass of the gypsum. Concrete cured product according to claim 1, wherein the expandable admixture in the concrete cured body 1 m ³ is to formulate the expandable admixture to include 10～40Kg.   The blend is 0 to 0.05 to 1.5 parts by mass of tartaric acid or a salt thereof and / or heptonic acid in terms of tartaric acid with respect to a total of 100 parts by mass of the hydraulic composition and the expandable admixture. The hardened concrete body according to any one of claims 1 to 5, further comprising 0.05 to 1.5 parts by mass of heptonic acid or a salt thereof.   The said formulation further contains 0.01-0.3 mass part boric acid or its salt in conversion of a boric acid with respect to a total of 100 mass parts of the said hydraulic composition and an expansive admixture. The hardened concrete body according to claim 1. The specific surface area is 1000 to 4000 cm with respect to 100 parts by mass of calcium sulfoaluminate composition containing 3 to 60% by mass of calcium sulfoaluminate (3CaO.3Al ₂ O ₃ .CaSO ₄ ) and 1 to 40% by mass of anhydrous gypsum. ^A hydraulic composition containing 0.1 to 3.0 parts by mass of ² / g lithium carbonate;
_{3CaO · SiO 2 -2CaO · SiO 2} -CaO- gap material based composition, 3CaO _· SiO 2 -CaO- gap material based composition, 2CaO _· SiO 2 -CaO- gap material based composition, and CaO gap material based composition A clinker composition containing one or two or more compositions selected from the group consisting of a product and having a CaO content of 50 to 92% by mass, and an expandable admixture containing gypsum A concrete composition.   The concrete composition according to claim 8, wherein the expandable admixture includes 5 to 50 parts by mass of the gypsum with respect to 100 parts by mass of the clinker composition.   The concrete composition according to claim 8, wherein the expandable admixture further contains quicklime. The expandable admixture contains 20 parts by mass or more of the clinker composition in a total of 100 parts by mass of the clinker composition and the quicklime, and the total of 100 parts by mass of the clinker composition and the quicklime. The concrete composition according to claim 10 , further comprising 5 to 50 parts by mass of the gypsum. 12. The expandable admixture is blended so that 10 to 40 kg of the expandable admixture is contained in 1 m ^{3 of a} hardened concrete body obtained by curing the concrete composition. The concrete composition according to 1.   For a total of 100 parts by mass of the hydraulic composition and the expandable admixture, 0.05 to 1.5 parts by mass of tartaric acid or a salt thereof and / or heptonic acid in terms of 0.05 to 1. The concrete composition according to any one of claims 8 to 12, further comprising 5 parts by mass of heptonic acid or a salt thereof.   The boric acid or its salt is further included in 0.01-0.3 mass part in conversion of boric acid with respect to a total of 100 mass parts of the said hydraulic composition and an expansive admixture. ~ 13 concrete composition.

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