JP2014129210A - Expansive admixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an expansive admixture having a scarce temperature dependence, namely an expansive admixture yielding, even when used at 10 to 30°C, a stable expansion coefficient of a concrete mixed therewith and unlikely to yield a strength attenuation in comparison with an expansive material-free concrete and to provide an expansive concrete exhibiting, even when used at 10 to 30°C, a stable expansion coefficient and unlikely to yield a strength attenuation in comparison with an expansive material-free concrete.SOLUTION: The provided expansive admixture includes an expansive fired product including free quicklime particles having specified sizes. In other words, the provided expansive admixture includes an expansive fired product including free quicklime in a state where the content of particles of 10 μm or smaller (L1), the content of particles of 40 to 70 μm (M1), the content of particles of 70 to 100 μm (M2), and the content of particles of 100 to 150 μm (H1) within the expansive fired product are confined respectively to specified ranges. An expansive concrete including any of these expansive materials, cement, an aggregate, and water is also provided.

Description

  The present invention relates to an expansion material. More specifically, there is little temperature dependency, and even if it is used at 10 to 30 ° C., the expansion rate of the mixed concrete is stable and the strength is hardly lowered as compared with the concrete without the addition of the expansion material, and an expansion material can be obtained.

  In concrete, shrinkage occurs when the moisture content in the concrete decreases after hardening due to the hydration reaction of the cement and evaporation from the surface. Cracks occur when the stress due to shrinkage increases. Most concrete structures contain steel such as reinforcing bars and steel frames inside. When a crack is generated in a concrete structure containing such a steel material and the crack reaches the vicinity of the steel material, the concrete structure is easily deteriorated. For this reason, it is widely practiced to prevent the occurrence of cracks by reducing the stress generated by shrinkage by preliminarily expanding by adding an expansion material to concrete. As such an expansion material used for concrete, there is a lime-based expansion material. This lime-based expansion material is obtained by adjusting the particle size of a baked product containing quick lime or CaO crystals (free lime) as a main component (see, for example, Patent Document 1).

JP 2007-131484 A

  By the way, since the reaction of the expansion material is temperature-dependent like the cement hydration reaction, if the temperature is different in the existing technology, the expansion of the concrete may be excessive or insufficient, or the compressive strength may be insufficient. . For this reason, the expansion | swelling material with little temperature dependence was desired.

  The present invention relates to an expansion material having a low temperature dependency, that is, an expansion material in which the expansion rate of the mixed concrete is stable even when used at 10 to 30 ° C. and the strength is not easily lowered as compared with the concrete without the addition of the expansion material. The purpose is to provide. Another object of the present invention is to provide an expanded concrete that has a stable expansion rate and is less likely to experience a decrease in strength when compared with concrete containing no expansion material even when used at 10 to 30 ° C.

As a result of intensive investigations for solving the above problems, the present inventors have found that the present invention solves the above problems by containing an expansive calcined product containing free quick lime having a specific particle size, thereby completing the present invention. It was. The present invention is an expanded material represented by the following (1) or (2) and expanded concrete represented by (3).
(1) It contains an expansive calcined product containing free quick lime, and the expansive calcined product has a content of particles of 10 μm or less of 10 to 30%, a content of particles of 40 to 70 μm of 19 to 30%, An expansion material having a content of 70 to 100 μm particles of 8 to 25% and a content of 100 to 150 μm particles of 5 to 15%.
(2) Furthermore, the content rate of particles of 10 μm or less is L1, the content rate of particles of 40 to 70 μm is M1, the content rate M2 of particles of 70 to 100 μm and the content rate H1 of particles of 100 to 150 μm are the following formula ( 1) and the expansion material of the above (1) that satisfies the formula (2).
1.0 ≦ M1 / L1 ≦ 1.5 (1)
0.8 ≦ M2 / H1 ≦ 2.5 (2)
(3) Expanded concrete containing the expansion material, cement, aggregate and water of (1) or (2) above.

  According to the present invention, an expanded material with less temperature dependency can be obtained. That is, even if it is used at 10 to 30 ° C., an expanded material in which the expansion rate of the mixed concrete is stable and the strength is not easily lowered as compared with the concrete without the expanded material is obtained. According to the present invention, even if it is used at 10 to 30 ° C., the concrete expansion coefficient of the mixed concrete is 150 to 250 μm, and the excellent expansion performance that satisfies the restriction expansion coefficient of the concrete for shrinkage compensation specified by the Japan Society of Civil Engineers is exhibited. In addition, an expansion material in which the strength reduction is less than 0.95 at a material age of 28 days with respect to concrete to which no expansion material is added can be obtained. Further, according to the present invention, the rate of change of the constrained expansion rate of the concrete at 10 to 30 ° C. with respect to the constrained expansion rate of the concrete at 20 ° C. is within ± 10%, and the expansion rate of the mixed concrete is stable. An inflatable material is obtained.

  According to the present invention, it is possible to obtain an expanded concrete having little temperature dependency. That is, even when used at 10 to 30 ° C., an expanded concrete is obtained in which the expansion rate is stable and the strength is not easily lowered as compared with the concrete without the addition of the expansion agent. According to the present invention, even when used at 10 to 30 ° C., the concrete expansion coefficient is 150 to 250 μm, and the excellent expansion performance of satisfying the limited expansion coefficient of the shrinkage compensation concrete of the Japan Society of Civil Engineers is exhibited, and The compressive strength ratio at the age of 28 days with respect to the concrete to which no expansive material is added is 0.95 or more, and an expansive concrete in which the strength is hardly lowered is obtained. In addition, according to the present invention, the expansion rate of the concrete with a restricted expansion rate is within a range of ± 10% within the range of the change rate of the restricted expansion rate of the concrete at 10 to 30 ° C. with respect to the restricted expansion rate of the concrete at 20 ° C. Is obtained.

The intumescent material of the present invention contains an expansive calcined product containing free quick lime, and the expansive calcined product has a particle content of 10 μm or less (L1) of 10 to 30% and 40 to 70 μm. The rate (M1) is 19 to 30%, the content rate (M2) of particles of 70 to 100 μm is 8 to 25%, and the content rate (H1) of particles of 100 to 150 μm is 5 to 15%. All percentages of content are mass%. If any of L1, M1, M2 or H1 is out of these ranges, the mixed concrete may have a restricted expansion rate of 150 to 250 μm when used at a temperature of 10 to 30 ° C., or expansion. There is a possibility that the compressive strength ratio at the age of 28 days with respect to the concrete to which no material is added is less than 0.9. However, the constrained expansion rate at 10 ° C. is the value of the material age 14 days, and 20-30 ° C. is the value of the material age 7 days. The preferable particle size ranges are 15 to 25% for L1, 19 to 30% for M1, 8 to 24% for M2, and 5 to 15% for H1. Furthermore, when the ratio of M1 to L1 (M1 / L1) is 1.0 to 1.5 and the ratio of M2 to H1 (M2 / H1) is 0.8 to 2.5, the constrained expansion of concrete at 20 ° C. The rate of change of the constrained expansion coefficient of the concrete at 10 to 30 ° C. with respect to the rate is more preferably within a range of 10% or less with respect to the constrained expansion coefficient of the concrete at 20 ° C., because the expansion coefficient of the mixed concrete is stable. Moreover, it is preferable since the content rate (H2) of the particle | grains exceeding 150 micrometers is less than 3%, and the spot and swelling by the slaked lime which arose by the hydration of the expansion material on the surface of hardened concrete are hard to understand visually. In the present invention, the rate of change (R _EX ) of the constrained expansion coefficient (EX _{T ° C.} ) of the concrete at T ° _C. relative to the constrained expansion coefficient (EX _{20 ° C.} ) of the concrete at _{20 ° C.} is obtained by the following equation (3). Is.
R _EX = (EXT _{T ° C.−} EX _{20 ° C.} ) ÷ EX _{20 ° C.} × 100 (%) (3)

  L1, M1, M2 and H1 can be obtained by a screening test using a vacuum suction type dry screening device (air jet sieve) using a sieve having openings corresponding to each particle size range. For example, if L1, a sieve with an opening of 10 μm is used, if M1, sieves of an opening of 40 μm and 70 μm are used, if M2, sieves of an opening of 70 μm and 100 μm are used, and if it is H1, an opening of 100 μm and Using a sieve of 150 μm, a remaining rate when each sieve is used is obtained by a sieving test using an air jet sieve, and L1, M1, M2, and H1 are calculated.

  The expansive calcined product containing free quick lime (CaO) in the present invention is a calcined product obtained by calcining a calcined raw material containing calciumaceous raw materials such as calcium carbonate, slaked lime and quick lime. In addition to the calcium raw material, a siliceous raw material, an alumina raw material, an iron oxide raw material, or the like may be added to the firing raw material. Examples of siliceous materials include diatomaceous earth, quartzite powder, silifume, fly ash, blast furnace slag, band shale, copper slag, clay minerals, and alumina materials include, for example, bauxite, alumina, fly ash, blast furnace slag, aluminum ash , Aluminum dross, band shale, clay mineral and the like, and examples of the iron oxide raw material include iron oxide, iron ore, copper slag, steelmaking slag and the like. The firing temperature when firing the firing raw material is preferably 1100 to 1500 ° C, more preferably 1200 to 1350 ° C. When the firing temperature is lower than 1100 ° C., the sinterability is low, and the crystals of free quick lime do not grow sufficiently, so that it is difficult to obtain good expansion performance. On the other hand, when the firing temperature exceeds 1500 ° C., the fuel consumption increases, the firing cost increases, and the sinterability is excessively increased, and it is difficult to obtain good expansion performance. For firing, it is preferable to use a temperature adjustable furnace such as a rotary kiln or an electric furnace.

  In order to make the expansive calcined product containing free quick lime into the above-mentioned particle size, a method of pulverizing while classifying so as to obtain the above particle size, a blending ratio such that two or more powders having different particle size distributions are produced by classification and the above particle size is obtained. Preferred examples include a method of mixing at 2), a method of preparing two or more powders having different particle size distributions by pulverization, and mixing at a blending ratio so as to obtain the above particle size. The pulverization, classification and mixing are preferably carried out in a dry manner, that is, in the form of powder because a drying step is not required. It is preferable to use a machine for pulverization, classification and mixing. For pulverization, for example, various pulverizers such as a rod mill, a ball mill, a vertical roller mill, a hammer mill, a jaw crusher, and a jet mill can be used. For classification, for example, various classifiers such as a vibration sieve including an ultrasonic sieve, a rotary sieve (Trommel), an air separator, and a centrifugal separator can be used. For mixing, various mixers (mixers) such as a V-type mixer and a gravitational mixer such as a tiltable concrete mixer, a Henschel mixer, a ribbon mixer, a pan-type concrete mixer, a pug mill mixer, and a hand mixer are used. be able to.

  The expansion material of the present invention may contain other components (admixtures) that can be used for, for example, mortar and concrete as long as the effects of the present invention are not substantially lost. Specific examples of such components include fibers, water reducing agents (including dispersants, high performance water reducing agents, AE water reducing agents, high performance AE water reducing agents, etc.), shrinkage reducing agents, pozzolans such as silica fume and fly ash. , Blast furnace slag powder, cement powder, gypsum, limestone powder, etc., setting accelerator, setting retarder, quick setting agent (material), quick hardening agent (material), thickener, water retention agent, rust preventive agent, air entrainment Examples thereof include agents, antifoaming agents, foaming agents, waterproofing agents, water repellents, anti-whitening agents, pigments, polymers for cement, foaming agents, and non-separable admixtures in water. Since the strength of the expanded concrete is high, it is preferable to include one or more selected from pozzolans, blast furnace slag powder, cement and gypsum, and anhydrous gypsum is preferable when gypsum is used.

The expanded concrete of the present invention contains the expanded material, cement, aggregate, and water. The amount of the expansion material (unit expansion material amount) is preferably 20 ± 10 kg / m ³ , since the expansion rate is easy to stabilize and the strength is less likely to decrease compared to concrete without the addition of a tension material, and more preferably. Is 20 ± 5 kg / m ³ .

  The cement used in the present invention may be a hydraulic cement. For example, ordinary, early strength, very early strength, low heat and moderate heat Portland cement, eco cement, and portland cement or eco cement, fly ash is used. , Blast furnace slag powder, various mixed cements mixed with silica fume, fine powder of limestone, etc., super fast cement such as "Super Jet Cement" (trade name) manufactured by Taiheiyo Cement Co., Ltd. and "Jet Cement" (trade name) manufactured by Sumitomo Osaka Cement Co., Ltd. , Alumina cement, and the like, and one or more of these can be used. It is preferable to use one or two or more selected from various Portland cements, eco-cements, and various mixed cements because it is difficult to impair the workability and it is easy to ensure a long pot life.

The aggregate used in the present invention may be any aggregate that can be used for mortar and concrete. For example, river sand, sea sand, mountain sand, crushed sand, artificial fine aggregate, slag fine aggregate, recycled fine aggregate Slag fine aggregate, quartz sand, stone powder, river gravel, land gravel, crushed stone, artificial coarse aggregate, recycled coarse aggregate, slag coarse aggregate, etc., one or more of these can be used . Generally, it is preferable if it is generally provided with the physical performance defined in Annex 1 of the standard JIS A 5005 “Crumble and sand for concrete” or JIS A 5308 “Ready mixed concrete”. Aggregates that meet any of these standards are more preferred. The amount of aggregate is preferably 1500~1900kg / ^{m 3,} to be further 1600~1800kg / ^{m 3,} preferably in the securing point of the worker capability over.

  The water used in the present invention is not particularly limited, and water contained in the admixture may be used. The blending amount of water is preferably 30 to 65 parts by mass with respect to 100 parts by mass of cement. If the amount is less than 30 parts by mass, the concrete consistency (slump) is small and the concrete is likely to be poorly filled with junkers or the like. If the amount exceeds 65 parts by mass, the possibility that the concrete will cause material separation increases. It is more preferable that the content of water is 35 to 60 parts by mass with respect to 100 parts by mass of cement because concrete is less likely to be poorly filled and material separation is unlikely.

  The expanded concrete of the present invention can be used in combination with one or two or more admixtures other than the above expandable material that can be used for mortar and concrete as long as the effects of the present invention are not substantially impaired. Examples of such admixtures include fibers such as organic fibers and metal fibers, cement dispersants (including water reducing agents, high performance water reducing agents, AE water reducing agents, high performance AE water reducing agents, fluidizing agents, etc.), shrinkage. Reducing agent, pozzolanes such as silica fume and fly ash, blast furnace slag powder, setting accelerator, setting retarder, thickener, water retention agent, rust preventive agent, air entraining agent, antifoaming agent, foaming agent, foaming agent, high Examples thereof include strength admixtures, waterproofing materials, water repellents, anti-whitening agents, pigments, quick-setting agents (materials), polymer for cement, stone powder such as gypsum and limestone powder, and non-separable admixtures in water.

  The expanded concrete of the present invention is produced by kneading with a mixer or the like. An apparatus and a kneading apparatus used for kneading are not particularly limited, but it is preferable to use a mixer because a large amount can be kneaded. The mixer that can be used may be a continuous mixer or a batch mixer, such as a pan concrete mixer, a pug mill concrete mixer, a gravity concrete mixer, a grout mixer, a hand mixer, and a plaster mixer. In addition, the materials may be put into a mixer at a time and kneaded, or the materials kneaded in two or more may be further kneaded and manufactured.

[Example 1]
A fired product obtained by firing a mixture of quartzite, bangshale shale, iron oxide, anhydrous gypsum and industrial quicklime at 1400 ° C. using an electric furnace was pulverized to produce an expansive fired product containing 50% by mass of free quicklime. . Main minerals other than the free quick lime contained in the expansive calcined product are trilime silicate (3CaO · SiO ₂ ) and anhydrous gypsum (CaSO ₄ ). The produced expansive fired product was pulverized with a ball mill, and sieved (classified) with a vacuum suction type dry sieving device (air jet sieve) using sieves with openings of 10 μm, 40 μm, 70 μm, 100 μm and 150 μm. . The classified expansive fired product was adjusted so as to have the ratio shown in Table 1, and 80 parts by weight of the adjusted expansible fired product and 20 parts by weight of type II anhydrous gypsum (Brain specific surface area of 7000 cm ² / g) were mixed. By doing so, the expansion material (No. 1-23) was produced.

The expanded concrete (No. 1-23) was produced using the produced expanded material (No. 1-23). Similarly, an expanded concrete (No. 24) was produced using a commercially available expandable material. The produced expanded concrete has a water cement ratio of 50.0%, a unit water amount of 168 kg / m ³ , a unit expansion material amount of 20 kg / m ³ , a target slump of 15.0 ± 2.0 cm, and a target air amount of 4.5 ± 1.0. %. Expanded concrete was produced at an environmental temperature and a material temperature of 10 ° C, 20 ° C, and 30 ° C. Table 2 shows the materials used for the expanded concrete, and Table 3 shows the composition of the expanded concrete. For concrete mixing, solid materials (cement, aggregate and expansion material) are added to the concrete mixer and mixed for 30 seconds (empty kneading), then liquid materials (water, AE water reducing agent and AE auxiliary agent). Was put into a mixer and mixed (mainly kneaded) for a total of 120 seconds. In this kneading, after mixing for 60 seconds, the mixer was once stopped and the cement adhering to the mixer was scraped off, and then mixed for another 60 seconds.

As an evaluation test of the produced expanded concrete, an expansion coefficient test, a compressive strength test, and a skin surface evaluation test were performed as shown below. The test results are shown in Table 4 (expansion coefficient test results) and Table 5 (compressive strength test results and skin surface evaluation test results).
<Quality test method>
-Expansion coefficient test A test was conducted in accordance with method A of JIS A 6202 "Expanding material for concrete" to obtain a restricted expansion coefficient. Moreover, the rate of change (R _EX ) of the concrete expansion coefficient (EX _{T ° C.} ) at _{T °} C. relative to the concrete expansion coefficient (EX _{20 ° C.} ) at _{20 ° C.} was determined. However, the constrained expansion rate of concrete at _{10 ° C} (EX _{10 ° C} ) is at the age of 14 days, and the constrained expansion rates at _{20 ° C} and _{30 ° C} (EX _{20 ° C} and EX _{30 ° C} ) are both at the age of 7 days. Is.
・ Compressive strength test Tested in accordance with JIS A 1180 “Compressive strength test method for concrete” to determine the compressive strength at 28 days of age, and ordinary portland cement is added instead of the expanded material without mixing the expanded material. The ratio of compressive strength to compressive strength of the concrete was determined. Concrete was demolded at a material age of 1 day, and then cured in water at various environmental temperatures until the test material age.
-Skin surface evaluation test The surface of the specimen in the compressive strength test was visually and finger touched to confirm the presence or absence of spots or swelling due to slaked lime generated by hydration of the expansion material. The case where the spot or bulge was seen was evaluated as x, and the case where the spot was not seen was evaluated as ◯.

  Expanded concrete (mixture No. 2-4, 6, 7) using the expansion material (mixture No. 2-4, 6, 7, 9-11, 14-16, 18, 19, 22) corresponding to the examples of the present invention. , 9-11, 14-16, 18, 19, 22), the concrete expansion coefficient of concrete is 150-250μ even when used at 10-30 ° C. The compression performance ratio at the age of 28 days with respect to the concrete containing no expansion material was 0.95 or more, and the strength did not decrease, and the temperature dependency was small. In addition, these expansive concretes have no visible spots or swelling due to slaked lime generated by the hydration of the expansive material on the surface of the hardened concrete, and the surface (skin surface) is smooth (all skin surface evaluations are “○”). Met.

  On the other hand, expanded concrete (formulation No. 1, 5, 8) using an expansion material (formulation No. 1, 5, 8, 12, 13, 17, 20, 21, 23, 24) that is not an example of the present invention. , 12, 13, 17, 20, 21, 23, 24), the constrained expansion coefficient of concrete deviated from 150 to 250 μm at at least one level of 10 ° C., 20 ° C. or 30 ° C. In addition, some of the blended concrete (mixture Nos. 8, 12, 20, and 23) had a large strength reduction at a compression strength ratio of less than 0.95 at 28 days of age with respect to the concrete without the expansion agent. .

Further, the above expressions (1) and (2) are satisfied, that is, the ratio of M1 to L1 (M1 / L1) is 1.0 to 1.5, and the ratio of M2 to H1 (M2 / H1) is 0.8. Expanded concrete (mixing No. 2, 3, 6, 7) using an expansion material (mixing No. 2, 3, 6, 7, 10, 11, 14, 15, 18, 19, 22) of ~ 2.5 , 10, 11, 14, 15, 18, 19, 22), the rate of change of the constrained expansion coefficient of concrete at 10 to 30 ° C. (R _EX ) relative to the constrained expansion coefficient of concrete at _{20 ° C.} (EX _{20 ° C.} ). ) Is within ± 10%, and the expansion rate of the expanded concrete was stable.

  The expandable material and the expanded concrete of the present invention can be used for building structures such as reinforced concrete buildings and steel concrete buildings, and civil structures such as reinforced concrete road decks and reinforced concrete bridge piers.

Claims (3)

  It contains an expansive calcined product containing free quick lime, and the expansive calcined product has a content of particles of 10 μm or less of 10-30%, a content of particles of 40-70 μm of 19-30%, 70- An expanding material having a content of 100 μm particles of 8 to 25% and a content of 100 to 150 μm particles of 5 to 15%. Furthermore, the content rate of particles of 10 μm or less is L1, the content rate of particles of 40 to 70 μm is M1, the content rate M2 of particles of 70 to 100 μm and the content rate H1 of particles of 100 to 150 μm are the following formulas (1) and The inflatable material according to claim 1, which satisfies the formula (2).
1.0 ≦ M1 / L1 ≦ 1.5 (1)
0.8 ≦ M2 / H1 ≦ 2.5 (2)   An expanded concrete containing the expanded material, cement, aggregate and water according to claim 1 or 2.