JP5892696B2 - Concrete composition and concrete hardened body using blast furnace cement - Google Patents

Description

The present invention relates to a concrete composition using a blast furnace cement and a hardened concrete body. Hardened concrete is a basic structure that builds social capital such as buildings and civil engineering structures. Looking at the energy and CO ₂ basic units required for construction (hereinafter simply referred to as CO ₂ basic units), for example, In the case of a reinforced concrete building, 30 to 40% of the CO ₂ basic unit required for the construction of the entire building is derived from the hardened concrete. That is, to reduce the construction required CO ₂ per unit of building such infrastructure, to permit small construction environmental impact is of vital it possible to reduce the CO ₂ emissions per unit of concrete cured body. The cement composition and the aggregate are mainly composed of the concrete composition used for obtaining the hardened concrete body. The CO ₂ basic unit of the cement is about 750 kg-CO ₂ / ton (cement), and this value is It is nearly two orders of magnitude larger than the CO ₂ required for aggregate production. Thus, cement per concrete composition 1 m ³ is 300 to 400 kg, even taking into account that the amount of the aggregate is often 1800~2000kg and aggregate amount, the majority of the CO ₂ from the concrete composition of the cement Of CO ₂ . That is, in order to reduce the CO ₂ emissions per unit of concrete composition in order to build a small buildings and civil engineering structures with less environmental impact CO ₂ per unit of is necessary to reduce the CO ₂ emissions per unit of cement is there. The CO ₂ basic unit required for the production of ordinary Portland cement is separated from CaCO ₃ in the process of firing raw material limestone (CaCO ₃ ), and unavoidably generated CO ₂ is about 450 kg / ton (cement). Since the amount of cement produced in Japan is about 50 million tons / year, the amount of CO ₂ generated from cement is an enormous amount equivalent to about 3% of the amount of CO ₂ generated in Japan (1.3 billion tons). Use of blast furnace slag, a by-product of the steel industry, is effective in reducing the CO ₂ intensity required for the production of Portland cement. A material obtained by mixing an appropriate amount of blast furnace slag with Portland cement has the same hydraulic properties as Portland cement, and can be used not only as a binder, but also significantly suppress the amount of CO ₂ generated. In order to use blast furnace slag as cement, it is necessary to pulverize granulated blast furnace slag in the steel industry to the same size as cement to produce fine blast furnace slag powder. The CO ₂ required for production is 1/10 or less of the CO ₂ required for the production of Portland cement, and contributes to the reduction of CO _{2 in the} cement by the amount replaced with Portland cement by blast furnace slag fine powder. Of the blast furnace slag produced between 2000 and 25 million tons per year, about 7 million tons are exported without being used in the country. By utilizing blast furnace slag such unutilized enables reduction CO ₂ per unit for the production of Portland cement, building a further concrete composition and its cured product, the CO ₂ emissions per unit of civil engineering structures It can be made smaller. The present invention relates to a concrete composition using a blast furnace cement having a higher blast furnace slag content than a conventional blast furnace cement, and a hardened concrete body obtained by curing the concrete composition.

Cement using blast furnace slag fine powder instead of part of Portland cement is blast furnace cement. Production of blast furnace cement in Japan has begun almost at the same time as steel production. In 1913, a blast furnace cement factory was already in operation. JIS has also been established for blast furnace cement (JIS-R5211), depending on the content of fine blast furnace slag powder, type A (over 5% to 30% or less), type B (over 30% to 60% or less) And C type (over 60% and 70% or less). However, the blast furnace cement actually manufactured and distributed is almost 100% of the type B blast furnace cement B having a blast furnace slag fine powder content of 40 to 45%. Blast furnace cement has not only less CO ₂ unit during production than Portland cement, but also has less calorific value when cement hardens by reacting with water, hardly cracks, and has alkali silica reactivity. Therefore, it has an effect of suppressing the reaction to the aggregate that generates cracks in the hardened concrete body, and has quality advantages such as suppressing the ingress of chloride in the marine environment. However, these effects cannot be expected with blast furnace cement type A because the content of fine blast furnace slag powder is small. On the other hand, if the content of the blast furnace slag fine powder is more than about 45%, the hardening of the cement becomes slow, and the strength of the initial age of 1 to 3 days after the concrete is cast becomes low, which hinders concrete work. Further, when the blast furnace slag content is increased, drying shrinkage is increased and cracks are easily generated. Furthermore, neutralization of the hardened concrete becomes faster, and it becomes difficult to ensure durability in a reinforced concrete structure whose life is determined by neutralization. For these reasons, the blast furnace cement JIS stipulates three types of blast furnace slag fine powder, A type, B type, and C type, but the blast furnace slag fine powder is one of the types of blast furnace cement B. Only blast furnace cement whose content is limited to 40-45% has been manufactured and distributed.

  Production of a concrete composition with high environmental performance that suppresses the generation of CO2 by further increasing the content of blast furnace slag fine powder to the blast furnace cement with a blast furnace slag fine powder content of 40-45% that is currently distributed. Is possible. At the same time, it is possible to enhance the property of suppressing cracking due to heat of hydration and alkali silica reaction, and to suppress the invasion of chloride in the marine environment. Therefore, various techniques for improving the weaknesses of the concrete composition using blast furnace cement such as initial strength and drying shrinkage have been proposed. For example, a technology for improving the initial strength by increasing the fineness of the blast furnace slag fine powder and reducing the particle diameter (see, for example, Patent Document 1 and Patent Document 2). Since the long-term strength decreases even if it is increased, a technique for ensuring long-term strength by adding a component that suppresses the initial hydration reaction (see, for example, Patent Document 3), a fine powder having pozzolanic activity such as silica fume, etc. In order to suppress both the initial strength and the long-term strength (for example, see Patent Document 4), the shrinkage of the hardened concrete using blast furnace cement, and the heat generation due to hydration of the cement, Technology that uses reduced coarse blast furnace slag powder and anhydrous gypsum (see, for example, Patent Document 5), Technology that uses coarse blast furnace slag fine powder and expanded components with reduced fineness ( Eg to Patent Document 6 reference) it has been proposed. In addition, in order to impart fluidity to a concrete composition prepared using a blast furnace cement in which the content of blast furnace slag fine powder is increased, a technique using a specific cement dispersant has also been proposed (for example, Patent Documents 7 to 7). 11).

However, the conventional techniques of Patent Documents 1 to 4 require a large CO ₂ basic unit required for finely pulverizing blast furnace slag, which is expensive, and is liable to cause cracks due to drying shrinkage of the resulting cured body, which remains unsolved. There is a problem of becoming. Moreover, the prior arts of Patent Documents 5 and 6 have a problem that the initial strength of the obtained cured body is low and this remains unsolvable. Moreover, the prior arts of Patent Documents 1 to 6 have a problem that it is difficult to ensure fluidity, which is an essential requirement for the construction of a concrete composition using blast furnace slag fine powder. On the other hand, in the conventional techniques of Patent Documents 7 to 11, in addition to the development of initial strength and prevention of drying shrinkage cracks, etc., there is a corresponding effect in securing fluidity, but the temporal degradation of fluidity is suppressed. There is a problem that the fluidity retention action is insufficient. In concrete work, which is manufactured in a ready-mixed concrete factory and then transported to a construction site, construction work becomes difficult if the fluidity of the prepared concrete composition decreases, so fluidity retention performance is indispensable as a concrete composition. It is a requirement. According to the tests of the present inventors, in addition to the above problems, the concrete composition using blast furnace cement having a high content of blast furnace slag fine powder as in Patent Documents 1 to 11 is gypsum in the blast furnace cement. It has been clarified that depending on the amount of air and the amount of air in the concrete composition, problems arise in the freeze-thaw resistance of the resulting cured body and the fire resistance that resists explosion in the event of a fire. Freezing and thawing resistance is an indispensable requirement in cold regions, and fire resistance is also an indispensable requirement for all buildings and tunnels. In short, the conventional techniques of Patent Documents 1 to 11 have a serious problem in any one of the following points 1) to 7). 1) Low initial strength at 1 to 3 days of age 2) Large dry shrinkage and easy cracking 3) Neutralization is difficult and durability is difficult to secure 4) Fluidity required for construction is secured 5) Difficult to maintain fluidity for the required time, 6) Difficult to ensure freeze-thaw resistance, 7) Difficult to ensure fire resistance.

Japanese Patent Laid-Open No. 61-242942 JP 61-281577 A1 JP-A-5-155648 JP 2002-321949 A JP 2005-281123 A JP 2007-217193 A JP 2010-285289 A JP 2010-285290 A JP 2010-285291 A JP 2010-285292 A JP 2010-285293 A

  The problems to be solved by the present invention are as follows: 1) good initial strength development, 2) small drying shrinkage, 3) neutralization can be suppressed, 4) good fluidity, and 5) fluid retention over time. 6) Good freeze-thaw resistance, 7) Good fire resistance, blast furnace cement with a high content of fine blast furnace slag powder that can satisfy the above requirements 1) to 7) at the same time was used. The present invention provides a concrete composition and a hardened concrete body obtained by curing the concrete composition.

  Therefore, as a result of intensive studies to solve the above problems, the present inventors have found that a concrete composition using a combination of a binder containing a specific blast furnace cement and a specific admixture is suitable and suitable. I found it.

That is, the present invention is a concrete composition comprising a binder, water, fine aggregate, coarse aggregate, and an admixture, wherein the binder contains 70% by mass or more of the following blast furnace cement in the binder. In addition, as a part of the admixture, the following water-soluble vinyl copolymer is 0.1 to 5.0 % by mass of the binder , and gluconate and / or sucrose is 0.002 to 0.5 % of the binder. be one having mass% containing, water containing 15 to 60 wt% of the binder, that is further quantity of calcium hydroxide remaining after hydration of binder concrete composition 1 m ³ per 5kg or more The present invention relates to a concrete composition using a featured blast furnace cement. The present invention also relates to a cured concrete body obtained by curing such a concrete composition.

Blast Furnace Cement: 45 to 75% by mass of fine powder of blast furnace slag having a fineness of 3000 to 8000 cm ² / g, 20 to 50% by mass of Portland cement, and 1.0 to 4.5% by mass of sulfate in terms of SO ₃ ( Blast furnace cement containing at a ratio of 100% by mass in total.

  Water-soluble vinyl copolymer: One or two or more water-soluble vinyl copolymers selected from the following water-soluble vinyl copolymer A and water-soluble vinyl copolymer B below.

  Water-soluble vinyl copolymer A: 35 to 85 mol% of the following structural unit X in the molecule, 15 to 65 mol% of the following structural unit Y and 0 to 5 mol% of the following structural unit Z (total of 100 mol) %) A water-soluble vinyl copolymer having a mass average molecular weight of 2000 to 80000.

  Structural unit X: a structural unit selected from a structural unit formed from methacrylic acid and a structural unit formed from methacrylate.

  Structural unit Y: a structural unit formed from methoxypolyethylene glycol methacrylate having a polyoxyethylene group composed of 7 to 150 oxyethylene units in the molecule.

  Structural unit Z: a structural unit selected from a structural unit formed from (meth) allyl sulfonate and a structural unit formed from methyl (meth) acrylate.

  Water-soluble vinyl copolymer B: mass average molecular weight 2000 to 80000 having 40 to 60 mol% of the following structural unit L and 60 to 40 mol% (100 mol% in total) of the following structural unit M in the molecule Water-soluble vinyl copolymer.

  Structural unit L: a structural unit selected from a structural unit formed from maleic acid and a structural unit formed from maleate.

  Structural unit M: structural unit formed from α-allyl-ω-methyl-polyoxyethylene having a polyoxyethylene group composed of 15 to 80 oxyethylene units in the molecule and 15 to 80 in the molecule A structural unit selected from structural units formed from α-allyl-ω-hydroxy-polyoxyethylene having a polyoxyalkylene group composed of oxyethylene units.

  First, the blast furnace cement used for the concrete composition according to the present invention will be described. As a result of various studies on the material composition of blast furnace cement, the present inventors have found that there is an appropriate amount for imparting preferable performance and an appropriate amount for avoiding undesirable performance for sulfates such as gypsum. It was found that it is important to balance to an optimal amount.

FIG. 1 shows that the mass ratio of blast furnace slag fine powder having a fineness of 6000 cm ² / g and ordinary Portland cement is 2: 1, and anhydrous gypsum is changed in the range of 0 to 6% by mass in terms of SO ₃ as sulfate. Others show the compressive strength of the hardened concrete when the concrete composition prepared under the same conditions is hardened at five ages. In FIG. 1, 11 is the age of 1 day, 12 is the age of 3 days, 13 is the age of 7 days, 14 is the age of 28 days, and 15 is the age of 91 days. However, if the SO ₃ equivalent amount is less than 1% by mass, the initial strength is remarkably low. Conversely, if the SO ₃ equivalent amount exceeds 4.5% by mass, the long-term strength decreases.

FIG. 2 shows the drying shrinkage strain of the hardened concrete obtained in the same manner as in FIG. 1 tested by JIS A1129. SO ₃ in terms of weight is less than 1% by mass relative to become what easily than dry shrinkage is large enters the cracks when a conventional blast furnace cement (B species), SO ₃ equivalent amount is conventionally 1 wt% or more The blast furnace cement (type B) has less drying shrinkage and is less likely to crack, and this preferable performance increases as the SO ₃ equivalent amount increases.

FIG. 3 shows the resistance to freezing and thawing (relative dynamic elastic modulus) of the hardened concrete obtained in the same manner as in FIG. When the SO ₃ conversion amount is 4.5% by mass or less, the initial dynamic elastic modulus can be maintained at 80% or more until 300 cycles after repeated freezing and thawing, whereas the SO ₃ conversion amount is 4.5% by mass. If it exceeds the maximum, the kinematic elastic modulus will decrease rapidly, and the freeze-thaw resistance will decrease, making it unsuitable for use in cold regions.

FIG. 4 shows the state of explosion occurrence (mass) when a reinforced concrete column having a cross section of 20 × 20 cm and a height of 60 cm obtained in the same manner as in FIG. 1 is heated for about 30 minutes according to the standard heating curve defined in ISO834. (Decrease rate). When the SO ₃ conversion amount is 3.5% by mass or less, no explosion occurs and the fire resistance is sufficient at the time of fire. Even when the SO ₃ conversion amount is 4.5% by mass, the explosion is slight. When the SO ₃ equivalent exceeds 4.5% by mass, a considerable amount of explosion occurs, and in the case of a hardened concrete where such an amount of explosion occurs, the fire resistance required in the case of a building pillar It has become difficult to secure.

As described above, in order to keep the performance of the obtained hardened concrete within a preferable range, it is not preferable that the amount of SO ₃ equivalent of sulfate such as gypsum used for blast furnace cement is too large or too small. The range of 0.0 to 4.5% by mass is optimal. Moreover, the strength expression of the concrete composition using the blast furnace cement containing 45% by mass or more of blast furnace slag fine powder is equivalent to the concrete composition using the blast furnace cement (the amount of blast furnace slag fine powder of 40 to 45% by mass) that has been distributed in the past. In order to achieve this, it is important to simultaneously set both the fineness of the blast furnace slag fine powder and the SO ₃ equivalent amount of sulfate such as gypsum to an appropriate range, and the SO ₃ equivalent amount is 1.0 to 4. The fineness of the blast furnace slag fine powder at this time is preferably 3000 to 8000 cm ² / g. When the fineness of the blast furnace slag fine powder exceeds 8000 cm ² / g, a hardened concrete body having a high initial strength is obtained, but the long-term strength after the age of 28 days is lowered and the fluidity is also lowered. On the other hand, when the fineness of the blast furnace slag fine powder is less than 3000 cm ² / g, the initial strength of the obtained concrete cured body is lowered. By setting the fineness of the blast furnace slag fine powder and the SO ₃ equivalent amount of sulfate to the above range, the performance when using blast furnace cement with a blast furnace slag fine powder content of 45% by mass or more has been distributed. Although it can be equivalent to the case where blast furnace cement is used, when the content of blast furnace slag fine powder exceeds 75% by mass, the strength of the resulting hardened concrete, drying shrinkage strain, freeze-thaw resistance, etc. It becomes difficult to maintain the same performance as the case where blast furnace cement distributed from is used. The kind of sulfate to be used is not particularly limited. For example, gypsum can be used. As the gypsum, any of anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum can be used, and anhydrous gypsum is preferable .

In the concrete composition according to the present invention, when a blast furnace cement containing 45 to 75% by mass of blast furnace slag fine powder is used as a binder, the performance of the concrete composition can be improved by adding a material other than the blast furnace cement as a binder. Can be improved. As long as the performance of the concrete composition is improved, the material to be added is not particularly limited, but if the addition amount exceeds 30% by mass, the environmental performance and mechanical performance of the blast furnace cement may be insufficient. This is not preferable. Examples of the material include fine limestone powder having a fineness of 3000 to 12000 cm ² / g and a CaCO ₃ content of 70% by mass or more. The fine limestone powder is 3 to 20% by mass in the binder, preferably It can be used by containing 5 to 15% by mass. By using such limestone fine powder, the fluidity of the concrete composition having a water binder ratio of 20 to 40% is improved, and the compressive strength is also improved. Examples of the material include silica fume having a fineness of 100,000 to 300,000 cm ² / g and a SiO ₂ content of 60% by mass or more. The silica fume is 3 to 15% by mass in the binder, preferably 5 to 10%. It can be used by containing in mass%. By using such silica fume, the fluidity of the concrete composition having a water binder ratio (ratio of the mass of water to the mass of the binder) of 30% or less is improved, and the compressive strength of the resulting concrete cured body is also improved. improves. As a result, it is possible to produce a concrete composition having a water binder ratio of 15 to 25%. With such a concrete composition, the blast furnace cement containing 45% by mass or more of blast furnace slag fine powder is used to improve the initial and long-term strength of the obtained concrete hardened body, and the neutralization is reduced to near zero. It becomes possible to suppress, and it is possible to improve the durability of the hardened concrete body obtained by using the blast furnace cement having a high content of blast furnace slag fine powder. Examples of materials other than blast furnace cement include fly ash having a fineness of 2500 cm ² / g or more, a SiO ₂ content of 45% by mass or more, and a loss on ignition of 5% by mass or less. 5 to 30% by mass, preferably 10 to 20% by mass, can be used. By using such fly ash, the fluidity of the concrete composition having a water binder ratio of 30 to 60% by mass is improved, and the compressive strength is also improved. In addition, since the neutralization tends to be faster in the case of adding fly ash than in the case of adding no fly ash, the neutralization does not reach the reinforcing bar during the scheduled service period according to the cover thickness of the reinforced concrete member to be applied. It is preferable to determine the water-cement ratio. In the concrete composition according to the present invention, the method for preparing the binder is not particularly limited as long as the binder having the composition defined in the present invention can be prepared. As a method for preparing the binder, blast furnace slag fine powder, Portland cement, gypsum, limestone fine powder, silica fume, fly ash, etc. are preferably mixed in a cement factory, but limestone fine powder, silica fume, fly ash are mixed separately. It can also be added in concrete factories.

  Next, in the concrete composition according to the present invention, the amount of calcium hydroxide remaining after the hydration reaction of the binder will be described. In order to protect the reinforcing bars in the reinforced concrete member from corrosion, it is necessary to set the pH of the pore solution in the hardened concrete body to 11.5 or more and passivate the reinforcing bars. In the hardened concrete, calcium hydroxide crystals generated by the hydration reaction of Portland cement remain, and as a result, the pH in the pore solution exceeds 12.5, which is the pH of the saturated solution of calcium hydroxide. keeping. As a result, the reinforcing steel in the hardened concrete body greatly exceeds pH = 11.5 or more necessary for passivation. However, if carbon dioxide in the atmosphere enters the hardened concrete body, a neutralization reaction between calcium hydroxide and carbon dioxide occurs, that is, neutralization, so that the neutralization front does not reach the reinforcing bar. The durability of many concrete structures is determined by neutralization. Even in blast furnace cement containing blast furnace slag fine powder, calcium hydroxide is generated by the hydration reaction of the Portland cement component, but a part of calcium hydroxide is consumed by the hydration reaction of the blast furnace slag fine powder. Moreover, when materials such as fly ash and silica fume are added as a binder, calcium hydroxide is also consumed by the hydration reaction of these materials. Therefore, in order to control the neutralization of the concrete composition using blast furnace cement, it is necessary to control the calcium hydroxide remaining after these hydration reactions.

As a result of various studies on the relationship between the amount of calcium hydroxide remaining after the hydration reaction of the binder and the neutralization rate of the hardened concrete, the present inventors have found a relationship as shown in FIG. The vertical axis in FIG. 5 represents a specimen made of a 10 × 10 × 40 cm hardened concrete from the concrete composition prepared using the binder as described above, and this specimen was subjected to JISA 1153: 2003 “Promotion of Concrete. A neutralization test was carried out at a carbon dioxide concentration of 5% according to the “Neutralization Test Method”, and a coefficient for determining the relationship between the square root of time and the neutralization depth was obtained from the result, that is, a neutralization rate coefficient was obtained. is there. Moreover, the horizontal axis of FIG. 5 shows the amount of residual calcium hydroxide at the age of 90 days measured by the following method after storing the same concrete composition in a sealed state. In FIG. 5, 51 is a case where the water binder ratio is 30% by mass, 52 is a case where the water binder ratio is 40% by mass, and 53 is a case where the water binder ratio is 50% by mass. Is the same, it can be seen that neutralization decreases as the amount of residual calcium hydroxide increases. The value of the neutralization rate coefficient = 3.5 shown by the broken line in FIG. 5 is a value necessary for securing a life of 65 years for a normal building member. When the lower limit of the water binder ratio of a normal economical concrete composition is 30% by mass, the residual calcium hydroxide amount should be 5 kg / m ³ or more in order to be less than the neutralization rate coefficient = 3.5. I understand that If the amount of residual calcium hydroxide is 10 kg / m ³ or more, the concrete composition can be prepared until the water binder ratio exceeds 30% by mass, and the amount of residual calcium hydroxide is 15 kg / m ³ or more. Then, it can be seen that the concrete composition can be prepared even when the water binder ratio is 40% by mass, which is preferable from the viewpoint of economy and workability.

  As a result of various studies on the amount of calcium hydroxide remaining after the hydration reaction of the binder, this amount is the composition of the blast furnace cement, the fineness of the blast furnace cement, the water binder ratio, the added amount of materials other than the blast furnace cement, It is influenced by various factors. Therefore, it is difficult to unambiguously determine such an important amount for controlling neutralization from the composition of the blast furnace cement, the water binder ratio, etc., and it is necessary to determine it by experiments on the prepared concrete composition. Met. The experimental method for this is as follows.

Amount of calcium hydroxide remaining after the hydration reaction of the binder (kg / m ³ ): After preparing the concrete composition, sealing and storing until the age of 90 days, taking out the hardened concrete, and pulverizing the whole amount The amount of CaO was determined by analysis according to “Quantitative method of free calcium oxide” (JCAS I-01-1997) established by the Cement Association, and the amount of calcium hydroxide per 1 m ^{3 of} concrete was determined from this value. However, the method for analyzing calcium hydroxide is not limited to this method as long as a correct value is obtained.

  Next, the admixture used for the concrete composition according to the present invention will be described. In order to ensure the fluidity of concrete compositions using blast furnace cement containing a large amount of fine powder of blast furnace slag, conventionally used cement dispersions such as lignin sulfonate and formalin high condensate salt of naphthalene sulfonate are used. Therefore, it is necessary to use a cement dispersant made of a specific water-soluble vinyl copolymer. In the concrete composition according to the present invention, the water-soluble vinyl copolymer is any one or two or more selected from the water-soluble vinyl copolymer A and the water-soluble vinyl copolymer B. A water-soluble vinyl copolymer is used. In the region where the water binder ratio is large, specifically, in the region where the water binder ratio is 35 to 60% by mass, it is preferable to use one selected from the water-soluble vinyl copolymer A, and the region where the water binder ratio is small. Specifically, in the region where the water binder ratio is 15 to 35% by mass, it is preferable to use one selected from the water-soluble vinyl copolymer B. Use mass%.

  In order to ensure the fluidity of the concrete composition that can be constructed at the construction site, it is not sufficient to ensure the fluidity immediately after the preparation of the concrete composition. It is necessary to suppress the fluidity of the prepared concrete composition from decreasing and maintain the fluidity. A concrete composition using a blast furnace cement having a high content of fine blast furnace slag powder has a larger decrease in fluidity than a concrete composition using a conventional Portland cement or a circulating blast furnace cement. In order to suppress such a decrease in fluidity, it is preferable to use a fluidity retention agent as an admixture in addition to the cement dispersant. As a result of various researches on fluidity retention agents when water-soluble vinyl copolymers are used as cement dispersants, the present inventors have found that fluidity retention agents include sodium gluconate, potassium gluconate, lithium gluconate, etc. It was found that gluconate and / or sucrose can be used, and sodium gluconate is particularly preferable. These fluidity-preserving agents are a kind of cement retarding component. However, in the concrete composition according to the present invention, the fluidity can be prevented from lowering by using it within a range of the addition amount having less influence of the retarding delay. The work can be increased. For this purpose, the fluidity-holding agent is used in the range of 0.002 to 0.5% by mass of the binder, but the water-soluble vinyl copolymer described above is 55 to 99% by mass, gluconate and / or salt. It is preferable to use a mixture of sugars in a ratio of 1 to 45% by mass (100% by mass in total) to form a one-component type, 75 to 99% by mass of a water-soluble vinyl copolymer, gluconate and / or It is more preferable to use a sucrose mixed at a ratio of 1 to 25% by mass (total 100% by mass) to make a one-pack type.

  The water-soluble vinyl copolymer is 55 to 98% by mass, the gluconate and / or sucrose is 1 to 20% by mass, and the compounds represented by the following chemical formula 1 are 1 to 25% by mass (total 100% by mass). It is preferable to use a multifunctional product that is mixed at a ratio of 1) to form a one-pack type. The water-soluble vinyl copolymer is 55 to 97% by mass and the gluconate and / or sucrose is 2 to 20%. It is more preferable to use a multifunctional compound in which the compounds represented by the following chemical formula 1 are mixed at a ratio of 1 to 20% by mass (total 100% by mass) to form a one-pack type. Such a multifunctional admixture is used by adding to the concrete composition in the range of 0.1 to 5% by mass, preferably 0.15 to 3% by mass of the binder in solid conversion. Here, the advantage of using a one-component admixture is that the admixture can be efficiently stored and metered in a ready-mixed concrete plant. In particular, the compound represented by Chemical Formula 1 reduces the drying shrinkage and self-shrinkage of the resulting hardened concrete, and is effective in suppressing shrinkage cracking. It reduces self-shrinkage for high-strength concrete with a small water binder ratio. It is effective for.

  In the compound represented by Chemical Formula 1, p, q and r are all 0 or a positive integer, and an integer satisfying p + q + r = 5 to 25. Especially, the case where all of p, q, and r are integers of 1-10, and satisfy | fills p + q + r = 7-20 is preferable. Further, p + q + r represents the number of moles of propylene oxide added relative to 1 mol of glycerin, and when p + q + r is less than 5, the viscosity reduction effect of the prepared concrete composition is not exhibited, and the resulting cured product is subjected to drying shrinkage and self-shrinkage. It is not possible to obtain the effect of reducing the above. On the other hand, when p + q + r is more than 25, it is difficult to dissolve in water and cannot be made into one component as a multifunctional admixture, and the viscosity reducing effect of the prepared concrete composition is not exhibited. The compound represented by Chemical Formula 1 can be synthesized by a known method.

  The compound represented by Chemical Formula 1, which is a propylene oxide adduct of glycerin, has a function of reducing friction generated between particles of glassy and hard blast furnace slag fine powder by an oily lubricating effect which is a basic property. Moreover, such a compound also has a drying shrinkage reducing performance and a self-shrinkage reducing performance, and both functions can be simultaneously imparted to the concrete composition.

Next, the air amount of the concrete composition according to the present invention will be described. In order to secure the resistance to freeze-thaw action of concrete structures constructed in cold regions, it is an indispensable requirement to adjust the amount of air in the concrete composition used for the construction. The amount of air in the concrete composition is usually 3.5 to 6.5% by volume, preferably 4.5 to 5.5% by volume, which can ensure freeze-thaw resistance. In order to ensure the freeze-thaw resistance of a concrete composition using a large amount of blast furnace cement, it is not sufficient to control the amount of air alone. Since the freeze-thaw resistance of such a concrete composition is also affected by the SO ₃ equivalent of sulfate such as gypsum, the air amount is set to 3.5 to 6.5% by volume, and the SO ₃ equivalent in blast furnace cement is further converted. It is necessary to make the amount 4.5% by mass or less. In the concrete composition according to the present invention, in order to adjust the air amount to 3.5 to 6.5% by volume, an alkyl phosphate monoester salt having 6 to 18 carbon atoms as a part of the admixture, especially the carbon number. It is preferable to contain 0.001-0.3 mass% of AE regulators which consist of octyl phosphoric acid monoester potassium salt of no.

Next, the water binder ratio of the concrete composition according to the present invention will be described. The concrete composition according to the present invention is composed of a binder, water, fine aggregate, coarse aggregate, and an admixture, and uses a binder containing the above-mentioned blast furnace cement, and water for the binder. Ratio, that is, a water binder ratio of 15 to 60%, preferably 30 to 50%, thereby providing a concrete composition excellent in drying shrinkage resistance, freeze-thaw resistance and fire resistance as well as initial strength and long-term strength. At the same time, it is possible to prepare a concrete composition that solves the problem of neutralization when a blast furnace cement having a high content of fine blast furnace slag powder is used. As shown in FIG. 5, the neutralization rate of the hardened concrete is governed by the amount of residual calcium hydroxide, but is also greatly influenced by the water binder ratio of the concrete composition used. That is, as long as the amount of calcium hydroxide remaining is the same, the durability of the obtained hardened concrete can be controlled by controlling the water binder ratio of the concrete composition to be prepared. For example, as described above, when the amount of residual calcium hydroxide is 10 kg / m ³ , a water binder ratio of 50% is insufficient, but if the water binder ratio is around 35%, durability is ensured. can do. If the amount of residual calcium hydroxide is about 20 kg / m ³ , the durability can be sufficiently ensured even if the water binder ratio is 50%. Further, if the cover thickness of the reinforced concrete member is 60 mm, the neutralization rate coefficient required for the hardened concrete to ensure a life of 65 years is 5.2, so the remaining calcium hydroxide amount is 10 kg / m. ³ , the water binder ratio may be 40%, and when the amount of remaining calcium hydroxide is 20 kg / m ³ , the water binder ratio can be greater than 50%. Thus, in the concrete composition according to the present invention, sufficient durability can be secured by controlling the water binder ratio together with the amount of calcium hydroxide remaining after the hydration reaction of the binder.

  Even in a concrete composition using a blast furnace cement containing a large amount of blast furnace slag, neutralization that determines the life of a concrete structure was the greatest weakness, but like the concrete composition according to the present invention, This problem can be solved by controlling the water cement ratio and the amount of calcium hydroxide remaining. Furthermore, if the progress of neutralization is predicted against the given conditions of the cover thickness of the structural member and the design life and the durability design is performed so as to satisfy the given conditions, a large amount of blast furnace slag is contained. Since concrete using blast furnace cement can be used for various structures, it is possible to construct a concrete structure with a low environmental load. As a usage method for solving the problem of neutralization of a hardened concrete body using a blast furnace cement containing a large amount of blast furnace slag fine powder of 45% by mass or more, it is prepared by using the durability design method as described above. In addition to the method for controlling the composition and the cover thickness of the concrete composition, there are several methods. One of them is a method of making a steel pipe concrete member and a steel pipe concrete structure using such a concrete composition. Since these are members or structures in which a steel pipe is used as a jacket and concrete is filled therein, the hardened concrete is not neutralized. Another method is to use such a concrete composition for a pile such as a building. Concrete piles in the ground are hardly neutralized because they are in water or in a humid environment with a humidity of almost 100%. The concrete composition according to the present invention can be preferably used for a pile.

  The method for preparing the concrete composition according to the present invention described above is not particularly limited and can be prepared by a known method. However, while the binder, water, fine aggregate and coarse aggregate are kneaded with a mixer, the above-described method is used. It is preferable to prepare by a method in which predetermined amounts of additives, multifunctional admixtures, air amount regulators, and the like are appropriately kneaded and diluted with water, and then both are kneaded. When preparing the concrete composition according to the present invention, additives such as an anti-separation agent, a setting accelerator, a rust preventive, a waterproofing agent, and an antiseptic are added as necessary within the range not impairing the effects of the present invention. These can be used in combination, and these are preferably used while being kneaded while being diluted with water.

  The concrete cured body according to the present invention is obtained by curing the concrete composition according to the present invention as described above. The curing method is not particularly limited, and a known method can be applied to this. Specific examples of the hardened concrete body according to the present invention include steel pipe concrete members and concrete piles as described above.

According to the present invention, on the premise of preparing a concrete composition excellent in environmental performance in which the CO ₂ basic unit of the hardened concrete body is greatly reduced, the fluidity during preparation is good and the fluidity is maintained over time. In addition to its excellent properties, it can prevent drying shrinkage of the resulting concrete cured body, express the required strength, satisfy freeze-thaw resistance, control neutralization, and ensure fire resistance. There is an effect that the required performance can be satisfied at the same time.

Change of compressive strength (vertical axis) of hardened concrete with respect to SO ₃ equivalent amount (horizontal axis) of sulfate in blast furnace cement when the age of the obtained hardened concrete body was changed from 1 to 91 days FIG. Graph illustrating the change in SO ₃ equivalent amount of sulfate blast furnace cement using concrete cured product obtained for (horizontal axis) Dry Shrinkage (vertical axis). Graph illustrating the change in SO ₃ equivalent amount of sulfate blast furnace cement using relative resilient coefficient of concrete cured product obtained for (horizontal axis) (vertical axis). Graph illustrating the change in SO ₃ equivalent amount of sulfate blast furnace cement using mass reduction rate of the concrete cured product obtained for (horizontal axis) (vertical axis). The graph which illustrates the change (vertical axis) of the neutralization rate coefficient with respect to the amount of residual calcium hydroxide (horizontal axis) of the used concrete composition when the water binder ratio of the concrete composition is changed by 30 to 50% .

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

Test category 1 (preparation of blast furnace cement)
Blast furnace cement was prepared using blast furnace slag fine powder, anhydrous gypsum, and ordinary Portland cement under the blending conditions shown in Table 1, and blast furnace cements (sb-1) to (sb-4) and (rb-1) to (rb rb-5) was obtained.

In Table 1,
sg-1: Fine powder of blast furnace slag having a fineness of 6150 cm ² / g sg-2: Fine powder of blast furnace slag having a fineness of 4100 cm ² / g sg-3: Fine powder of blast furnace slag having a fineness of 2050 cm ² / g sg- 4: Fine powder of blast furnace slag with a fineness of 9700 cm ² / g gp-1: Anhydrous gypsum with a fineness of 4080 cm ² / g pc-1: Normal Portland cement pc-2: Early strength Portland cement

Test Category 2 (Synthesis of water-soluble vinyl copolymer)
Synthesis of (a-1) as water-soluble vinyl copolymer A 60 g of methacrylic acid, methoxypoly (23 oxyethylene units, hereinafter n = 23) 300 g of ethylene glycol methacrylate, 5 g of sodium methallylsulfonate, 3-mercapto After charging 3 g of propionic acid and 490 g of water into the reaction vessel, 58 g of 48% aqueous sodium hydroxide solution was added, and the mixture was partially neutralized with stirring and dissolved uniformly. After the atmosphere in the reaction vessel was replaced with nitrogen, the temperature of the reaction system was maintained at 60 ° C. in a warm water bath, 25 g of a 20% aqueous solution of sodium persulfate was added to start radical polymerization reaction, and the reaction was continued for 5 hours. The reaction was terminated. Thereafter, 23 g of a 48% aqueous sodium hydroxide solution was added to completely neutralize the reaction product, thereby obtaining a 40% aqueous solution of the water-soluble vinyl copolymer (a-1). When the water-soluble vinyl copolymer (a-1) was analyzed, it was formed from a structural unit formed from sodium methacrylate / a structural unit formed from methoxypoly (n = 23) ethylene glycol methacrylate / sodium methallylsulfonate. The structural unit was a water-soluble vinyl copolymer having a mass average molecular weight of 35,500 (GPC method, converted to pullulan) having a ratio of 70/27/3 (mol%).

Synthesis of water-soluble vinyl copolymers (a-2) to (a-3) and (ar-1) to (ar-3) In the same manner as the water-soluble vinyl copolymer (a-1), water-soluble vinyl copolymers Copolymers (a-2) to (a-3) and (ar-1) to (ar-3) were synthesized. Table 2 summarizes the contents of the water-soluble vinyl copolymer A synthesized above.

In Table 2,
* 1: GPC method, pullulan conversion X-1: Sodium methacrylate X-2: Methacrylic acid Y-1: Methoxypoly (23 mol) ethylene glycol methacrylate Y-2: Methoxypoly (70 mol) ethylene glycol methacrylate Z-1: Meta Sodium rylsulfonate Z-2: Sodium allylsulfonate Z-3: Methyl acrylate

Synthesis of (b-1) as water-soluble vinyl copolymer B: Charge 98 g of maleic anhydride and 512 g of α-allyl-ω-methyl-poly (n = 33) oxyethylene into a reaction vessel and gradually warm it. Then, the mixture was uniformly dissolved with stirring, and the atmosphere in the reaction vessel was replaced with nitrogen. The temperature of the reaction system was maintained at 83 ° C. in warm water, and 2 g of benzoyl peroxide was added to initiate radical polymerization reaction. Further, 3 g of benzoyl peroxide was added in portions, and the radical polymerization reaction was continued for 4 hours. Water was added to the obtained copolymer for hydrolysis to obtain a 40% aqueous solution of the water-soluble vinyl copolymer (b-1). When the water-soluble vinyl copolymer (b-1) was analyzed, structural unit formed from maleic acid / structural unit formed from α-allyl-ω-methyl-polyoxyethylene (n = 33) = 50 / It was a water-soluble vinyl copolymer having a mass average molecular weight of 42,000 (GPC method, converted to pullulan) at a ratio of 50 (molar ratio).

Synthesis of water-soluble vinyl copolymer (b-3) α-allyl-ω-hydroxy-poly (n = 30) oxyethylene 1370 g (1.0 mol), maleic acid 116 g (1.0 mol) and water 1760 g Was uniformly dissolved with stirring, and the atmosphere was replaced with nitrogen. The temperature of the reaction system was kept at 60 ° C. in a warm water bath, and 8 g of a 20% aqueous solution of sodium persulfate was added to initiate radical polymerization reaction. Further, 5 g of a 20% aqueous solution of sodium persulfate was added and the radical polymerization reaction was continued for 5 hours to complete the reaction to obtain a water-soluble vinyl copolymer. Then, 167 g (2.0 mol) of a 48% aqueous sodium hydroxide solution was obtained. ) Was added to neutralize, and 390 g of water was added to obtain a 40% aqueous solution of the water-soluble vinyl copolymer (b-3). When the water-soluble vinyl copolymer (b-3) was analyzed, structural unit formed from sodium maleate / structural unit formed from α-allyl-ω-methyl-polyoxyethylene (n = 30) = 50. It was a water-soluble vinyl copolymer having a mass average molecular weight of 51600 (GPC method, converted to pullulan) at a ratio of / 50 (molar ratio).

Synthesis of water-soluble vinyl copolymer (b-2) and (br-1) to (br-2) In the same manner as for the water-soluble vinyl copolymer (b-1), the water-soluble vinyl copolymer (b- 2) and (br-1) to (br-2) were synthesized.

Synthesis of water-soluble vinyl copolymer (b-4) and (br-3) to (br-5) In the same manner as for the water-soluble vinyl copolymer (b-3), the water-soluble vinyl copolymer (b- 4) and (br-3) to (br-5) were synthesized. The contents of the water-soluble vinyl copolymer B synthesized above are summarized in Table 3.

In Table 3,
* 1: GPC method, pullulan conversion L-1: maleic acid L-2: sodium maleate L-1: α-allyl-ω-methyl-poly (n = 33) oxyethylene M-2: α-allyl-ω -Methyl-poly (n = 68) oxyethylene M-3: α-allyl-ω-hydroxy-poly (n = 30) oxyethylene M-4: α-allyl-ω-hydroxy-poly (n = 50) oxy Ethylene poly (m = 5) oxypropylene M-5: α-allyl-ω-hydroxy-poly (n = 105) oxyethylene M-6: α-allyl-ω-hydroxy-poly (n = 9) oxyethylene

Test Category 3 (Synthesis of compounds represented by Chemical Formula 1)
・ Synthesis of propylene oxide adduct (g-1) of glycerin, which is a compound represented by Chemical Formula 1, 184 g (2.0 mol) of glycerin was charged into an autoclave, and 1.8 g of potassium hydroxide was added as a catalyst. Was replaced with nitrogen. While stirring, the reaction temperature was kept at 125 to 140 ° C., and 1160 g (20 mol) of propylene oxide was injected to carry out an addition reaction. After completion of the press-fitting, the reaction was terminated by aging at the same temperature for 2 hours to obtain a product. In order to remove the residual catalyst of this product, it was subjected to adsorption treatment using an adsorbent and then purified by filtration. This purified product was a liquid compound at room temperature, and was a propylene oxide 10-mol adduct (g-1) of glycerin, which is a compound represented by Chemical Formula 1, according to the analysis results such as hydroxyl value.

・ Synthesis of propylene oxide adducts (g-2) and (g-3) of glycerin, which is a compound represented by Chemical Formula 1, in the same manner as the above propylene oxide adduct (g-1) of glycerin (G-2) and (g-3) were synthesized.

Synthesis of other glycerin propylene oxide adducts (gr-1) to (gr-3) In the same manner as the above glycerin propylene oxide adduct (g-1), other glycerin propylene oxide adducts, etc. (Gr-1) to (gr-3) were synthesized. The contents of the glycerin propylene oxide adduct synthesized above are shown in Table 4.

Test Category 4 (Preparation of multifunctional admixture)
-Preparation of multifunctional admixture (H-1) 225 parts of 40% aqueous solution of water-soluble vinyl copolymer (a-1) described in Table 2, 10 parts of sodium gluconate (first grade reagent) and 15 parts of water A multi-functional admixture (H-1) containing 90% water-soluble vinyl copolymer (a-1) and 10% sodium gluconate (100% in total) in a glass container with stirring and mixing. ) Was prepared.

-Preparation of multifunctional admixtures (H-2) to (H-4) In the same manner as the preparation of multifunctional admixture (H-1), multifunctional admixtures (H-2) to (H- 4) was prepared.

-Preparation of multifunctional admixture (H-5) 200 parts of 40% aqueous solution of water-soluble vinyl copolymer (a-1) described in Table 2, 10 parts of sodium gluconate (first grade reagent), listed in Table 4 10 parts of the compound (g-1) represented by Chemical Formula 1 and 30 parts of water were put into a glass container and mixed with stirring. 80% by mass of the water-soluble vinyl copolymer (a-1) and 10% of sodium gluconate were added. A 40% aqueous solution of a multifunctional admixture (H-5) containing 10% by mass (total 100% by mass) of the compound (g-1) represented by 1% by mass and chemical formula 1 was prepared.

・ Multifunctional admixtures (H-6) to (H-23)
In the same manner as the preparation of the multifunctional admixture (H-5), multifunctional admixtures (H-6) to (H-23) were prepared. The contents of each multifunctional admixture prepared above are summarized in Table 5.

In Table 5,
* 1: Water-soluble vinyl copolymer A in Table 2 synthesized in Test Category 2
* 2: Water-soluble vinyl copolymer B of Table 3 synthesized in Test Category 2
k-1: Sodium gluconate k-2: Sucrose * 3: Compound of Table 4 synthesized in test category 3 * 4: Naphthalenesulfonic acid formalin high condensate salt (High-performance water reducing agent for concrete manufactured by Takemoto Yushi Co., Ltd., Product name Pole Fine 510AN)
* 5: Melamine sulfonic acid formalin high condensate salt (Takemoto Yushi Co., Ltd. high-performance water reducing agent for concrete, trade name Pole Fine MF)
* 6: Lignin sulfonate (AE water reducing agent for concrete manufactured by Takemoto Yushi Co., Ltd., trade name Tupol EX20)

Test Category 5 (Preparation of concrete composition)
Examples 1-31
Using the multi-functional admixture described in Table 7 under the conditions of the formulation No. described in Table 6, the blast furnace cement and fine aggregate (Oikawa water system) prepared in Test Category 1 in a 50 liter bread type forced kneader mixer Land sand, density = 2.58 g / cm ³ ), coarse aggregate (Okazaki crushed stone, density = 2.68 g / cm ³ ), mixed water (tap water), Table 5 prepared in Test Category 4 A predetermined amount of an AE regulator mainly composed of octyl phosphate monoester potassium salt having 12 carbon atoms as a multifunctional admixture and an air amount regulator is added and kneaded for 90 seconds. The target slump is 18 ± 1 cm. A concrete composition using the blast furnace cement of Examples 1 to 31 described in Table 7 with a target air amount of 4.5 ± 1.0% was prepared, and the amount of residual calcium hydroxide was measured by the following method. The results are shown in Table 7.

Measurement of calcium hydroxide remaining after the hydration reaction of the binder: After preparing the concrete composition, seal it and store it until the age of 90 days. The amount per 1 m ^{3 of} the concrete composition was determined by analysis according to “Quantitative method of free calcium oxide” (JCASI-01-1997).

Comparative Examples 1-27
The concrete compositions of Comparative Examples 1 to 27 described in Table 8 were prepared in the same manner as in Examples 1 to 31, and the amount of residual calcium hydroxide was measured. The results are shown in Table 8.

In Table 6,
* 1: Ratio of blast furnace cement in the binder (mass%)
* 2: Silica fume fine powder with a fineness of 178000 cm ² / g and SiO ₂ content of 91%
* 3: Silica fume content in the amount of binder (%)
* 4: Fly ash fine powder with fineness of 3550 cm ² / g, SiO ₂ content of 56%, loss on ignition of 3.3% * 5: Content of fly ash in the amount of binder (%)
* 6: Fine limestone powder with a fineness of 8000 cm ² / g and CaCO ₃ content of 98% * 7: Content ratio (%) of fine limestone powder in the amount of binder
* 8: Fine aggregate (density = 2.58 g / cm ³ )
* 9: Coarse aggregate (density = 2.68 g / cm ³ )
* 10: Blast furnace type B cement (density = 3.04 g / cm ³ )

In Table 7 and Table 8,
* 1: Multifunctional admixture shown in Table 5 * 2: Mass parts in solid equivalent of multifunctional admixture (excluding AE agent) with respect to 100 parts of binder * 3: Sodium lignin sulfonate

Test Category 6 (Evaluation of prepared concrete composition)
About the prepared concrete composition of each example, the slump, the slump flow, the air amount, and the slump, the slump flow, and the air amount after standing for 60 minutes immediately after kneading are obtained as follows, and the results are shown in Table 9 and Table 10. Are summarized in In addition, the concrete composition of each example prepared was cured, and the obtained hardened concrete was determined as follows for compressive strength, drying shrinkage, freeze-thaw resistance, neutralization rate, and fire resistance. 11 and Table 12 collectively. Furthermore, the comprehensive evaluation based on the above results is summarized in Tables 13 and 14.

Slump (cm): Measured in accordance with JIS-A1101 for the concrete composition immediately after kneading and the concrete composition left on the kneading boat for 60 minutes.
-Slump residual rate (%): (slump value after standing for 60 minutes / slump value immediately after kneading) x 100.
Slump flow (cm): Measured in accordance with JIS-A1150 for the concrete composition immediately after kneading and the concrete composition left on the kneading boat for 60 minutes.
-Slump flow residual rate (%): (slump flow after standing for 60 minutes / slump flow immediately after kneading) x 100.
-Air amount (volume%): The concrete composition immediately after kneading and the concrete composition left on the kneading boat for 60 minutes were measured according to JIS-A1128.

-Compressive strength (N / mm < ² >): Based on JIS-A1108, the material age 7 days and the material age 28 days were measured.
-Drying shrinkage ratio (micro): In accordance with JIS-A1129, the length change was made by the comparator method for a test piece of 26 weeks of age in which the concrete composition of each example was stored at 20 ° C. × 60% RH. Measured and determined the drying shrinkage.
-Accelerated neutralization depth (mm): For the concrete composition of each example, the driving surface, bottom surface, and both end surfaces of a 10 × 10 × 40 cm square specimen were sealed with epoxy resin, and 20 ° C. × 60% RH The acceleration test was conducted under the condition of carbon dioxide concentration of 5%. The cross section of the specimen was cut at the age of 13 weeks, and a portion that did not turn red by spraying with a 1% phenolphthalein solution was regarded as a neutralized portion, and the width from the outside was defined as an accelerated neutralization depth. A smaller value indicates that neutralization does not progress and durability is excellent.
-Freezing and thawing durability index (300 cycles): For the concrete composition of each example, the value calculated according to ASTM-C666-75 durability index was shown using the value measured according to JIS-A1148. This numerical value indicates that the maximum value is 100, and the closer to 100, the better the resistance to freezing and thawing.
Fire resistance test: For each of the concrete compositions of each example, a specimen of a diameter 15 × height 30 cm which was cured in a sealed state at 20 ° C. for 28 days so that water vapor does not evaporate (a deformed bar rope having a diameter of 10 mm is arranged in the center). The seal was unwound and heated according to the standard heating curve defined in JISA1304, and the weight of the specimen before and after heating was measured. In this test, the explosive is lighter in weight and the difference in weight before and after heating is increased. Accordingly, a material with a small value of weight change (weight reduction rate) was evaluated as having excellent explosion resistance.

In Table 10,
* 1: Since the target slump was not obtained, it was not measured.
* 2: Slump flow * 3: Slump flow remaining rate

In Table 12,
* 1: Since the target slump was not obtained, it was not measured.

In Table 13 and Table 14,
○: The target value was cleared.
Δ: The target value could not be cleared because the level was not reached a little.
X: The target value could not be cleared at all.
In addition, the evaluation of neutralization made the numerical value of the comparative example 24 (blending using blast furnace cement B type) of Table 12 the target value.

As is clear from the results of Tables 7 to 14, on the premise that the CO ₂ basic unit of the hardened concrete can be reduced, the blast furnace cement having a specific component ratio and the admixture having the component ratio of a specific compound are optimal. The concrete composition used in combination within a wide range and the hardened concrete obtained by curing the concrete composition have 1) good fluidity after kneading, 2) good fluidity retention over time, and 3) initial strength. 4) Low drying shrinkage (low shrinkage cracking), 5) Suppress neutralization, 6) Excellent freeze-thaw resistance, 7) Excellent fire resistance, etc. At the same time, there is a satisfactory effect Moreover, there is an effect that the rust prevention performance of the reinforcing bars is excellent even though the concrete contains a high amount of blast furnace slag fine powder.

11 Polygonal line indicating compressive strength at 1 day of age 12 Polygonal line indicating compressive strength at 3 days of age 13 Polygonal line indicating compressive strength at 7 days of age 14 Polygonal line indicating compressive strength at age of 15 15 Age of 91 days Line showing compressive strength 51 Curve showing a neutralization rate coefficient with a water binder ratio of 30% 52 Curve showing a neutralization rate coefficient with a water binder ratio of 40% 53 Neutrality with a water binder ratio of 50% Curve showing the conversion rate coefficient

Claims (13)

A concrete composition comprising a binder, water, fine aggregate, coarse aggregate, and an admixture, wherein the binder contains 70% by mass or more of the following blast furnace cement, and the admixture is 0.1-5.0 wt% of a water-soluble vinyl copolymer described below as part binder, also those having 0.002 wt% free gluconate and / or sucrose binder A blast furnace cement characterized in that it contains 15 to 60% by weight of water of the binder, and the amount of calcium hydroxide remaining after the hydration reaction of the binder is 5 kg or more per 1 m ^{3 of the} concrete composition. Concrete composition using
Blast Furnace Cement: 45 to 75% by mass of fine powder of blast furnace slag having a fineness of 3000 to 8000 cm ² / g, 20 to 50% by mass of Portland cement, and 1.0 to 4.5% by mass of sulfate in terms of SO ₃ ( Blast furnace cement containing at a ratio of 100% by mass in total.
Water-soluble vinyl copolymer: One or two or more water-soluble vinyl copolymers selected from the following water-soluble vinyl copolymer A and water-soluble vinyl copolymer B below.
Water-soluble vinyl copolymer A: 35 to 85 mol% of the following structural unit X in the molecule, 15 to 65 mol% of the following structural unit Y and 0 to 5 mol% of the following structural unit Z (total of 100 mol) %) A water-soluble vinyl copolymer having a mass average molecular weight of 2000 to 80000.
Structural unit X: a structural unit selected from a structural unit formed from methacrylic acid and a structural unit formed from methacrylate.
Structural unit Y: a structural unit formed from methoxypolyethylene glycol methacrylate having a polyoxyethylene group composed of 7 to 150 oxyethylene units in the molecule.
Structural unit Z: a structural unit selected from a structural unit formed from (meth) allyl sulfonate and a structural unit formed from methyl (meth) acrylate.
Water-soluble vinyl copolymer B: mass average molecular weight 2000 to 80000 having 40 to 60 mol% of the following structural unit L and 60 to 40 mol% (100 mol% in total) of the following structural unit M in the molecule Water-soluble vinyl copolymer.
Structural unit L: a structural unit selected from a structural unit formed from maleic acid and a structural unit formed from maleate.
Structural unit M: structural unit formed from α-allyl-ω-methyl-polyoxyethylene having a polyoxyethylene group composed of 15 to 80 oxyethylene units in the molecule and 15 to 80 in the molecule A structural unit selected from structural units formed from α-allyl-ω-hydroxy-polyoxyethylene having a polyoxyalkylene group composed of oxyethylene units. The concrete composition according to claim 1, wherein the amount of calcium hydroxide remaining after the hydration reaction of the binder is 10 kg or more per 1 m ³ of the concrete composition. Claim 1 or 2 concrete composition according blast furnace cement is one having free anhydride gypsum as the sulphate. The binding material contains ₃ to 20% by mass of fine limestone powder having a fineness of 3000 to 12000 cm ² / g and a CaCO ₃ content of 70% by mass or more as a part thereof. A concrete composition according to one of the paragraphs. The binder according to any one of claims 1 to 4, wherein the binder contains 3 to 15% by mass of silica fume having a fineness of 100,000 to 300,000 cm ² / g and a SiO ₂ content of 60% by mass or more. The concrete composition described. The binder contains 5-30% by mass of fly ash having a fineness of 2500 cm ² / g or more, a content of SiO ² of 45% by mass or more, and an ignition loss of 5% by mass or less as a part thereof. The concrete composition according to any one of 1 to 5.   The concrete composition according to any one of claims 1 to 6, wherein the gluconate is sodium gluconate. Admixture of a water-soluble vinyl copolymer 55 to 99 wt%, a gluconate and / or sucrose 1 to 45 wt% so also were mixed at a ratio of (total 100 wt%) is according to claim 1-7 The concrete composition according to any one of the items. The admixture is 55 to 98% by mass of a water-soluble vinyl copolymer, 1 to 20% by mass of gluconate and / or sucrose, and 1 to 25% by mass of a compound represented by the following chemical formula 1 (total 100 masses). concrete composition of any one of the preceding of claims 1 to 7 in so was also mixed at a ratio of%).

(In Chemical Formula 1, p, q and r are all 0 or a positive integer and satisfy p + q + r = 5 to 25) The concrete composition according to any one of claims 1 to 9 , wherein the water-soluble vinyl copolymer is selected from water-soluble vinyl copolymers A and contains 35 to 60% by mass of water in the binder. The concrete composition according to any one of claims 1 to 9 , wherein the water-soluble vinyl copolymer is selected from water-soluble vinyl copolymers B and contains 15 to 35% by mass of water in the binder. AE containing 0.001 to 0.3% by mass of an alkyl phosphate monoester salt having 6 to 18 carbon atoms as a part of the admixture and having an air amount of 3.0 to 6.5% by volume. The concrete composition according to any one of claims 1 to 11 , which is a concrete composition. A hardened concrete body obtained by hardening the concrete composition according to any one of claims 1 to 12 .

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