JP6021260B2 - Hydraulic blast furnace slag composition and hardened concrete - Google Patents

Description

  The present invention relates to a hydraulic blast furnace slag composition and a hardened concrete body. In recent years, from the viewpoint of effective use of by-products, resource and energy savings, and reduction of carbon dioxide for global warming countermeasures, use of mixed cement mixed with fine powder of granulated blast furnace slag by-produced from steelworks with Portland cement However, it is becoming more and more important in obtaining a hardened concrete body. The present invention relates to a hydraulic blast furnace slag composition capable of obtaining a high-quality concrete cured body even when a binder containing a large amount of blast furnace slag fine powder is used, and a concrete cured body obtained by curing the composition.

It has been pointed out that when a concrete composition is prepared using a binder containing a large amount of blast furnace slag fine powder (hereinafter referred to as a binder containing a high amount of blast furnace slag), there are problems such as the following 1) and 2). . That is, 1) A concrete composition prepared using a binder containing a high content of blast furnace slag tends to have a lower compressive strength of the resulting concrete cured body than a concrete composition prepared using Portland cement (standard). The compressive strength of the underwater curing specimen is low). 2) When a concrete composition prepared using a binder containing a high content of blast furnace slag is applied to a large structure, if the prepared concrete composition is subjected to a heat history that rises in temperature due to heat generation in the process of hardening by a hydration reaction. There is a tendency that the structure strength of the obtained concrete hardened body tends to decrease (the compressive strength of the high-temperature hysteresis structure is low), and this tendency is higher when the temperature at the time of preparation (when kneading) is higher, and the blast furnace slag fine powder A concrete composition prepared using a binder having a high content is more remarkable. Conventionally, a concrete composition with high environmental performance in which generation of CO ₂ is suppressed by using a binder containing a high content of blast furnace slag is known (see, for example, Patent Document 1), and heat generation due to a hydration reaction of the concrete composition is suppressed. Admixtures and the like are also known (for example, see Patent Documents 2 to 8). However, these conventional techniques cannot solve the problems 1) and 2) simultaneously and sufficiently.

JP 2010-285291 A JP 59-30743 A JP-A-63-117941 JP-A-1-242447 JP-A-6-298560 JP 2003-34564 A JP 2009-7187 A JP 2010-180065 A

  Problems to be solved by the present invention are as follows. 1) A concrete composition prepared using a binder containing a high content of blast furnace slag (hereinafter, such a concrete composition is referred to as a hydraulic blast furnace slag composition) Two problems that the compressive strength is low 2) When the hydraulic blast furnace slag composition is subjected to a heat history that rises due to heat generation in the process of hardening by the hydration reaction, the compressive strength of the resulting concrete hardened body decreases. The present invention is to provide a hydraulic blast furnace slag composition capable of solving the above simultaneously and sufficiently and a concrete hardened body obtained by curing the composition.

  As a result of intensive studies to solve the above problems, the present inventors have found that a specific binder containing a specific admixture in a specific ratio is suitable.

  That is, the present invention is a hydraulic blast furnace slag composition containing the following binder, water, fine aggregate, coarse aggregate, and an admixture, and includes the following strength enhancer as a part of the admixture. It relates to the hydraulic blast furnace slag composition characterized by containing in the ratio of 0.01-0.50 mass part per mass part. Moreover, this invention concerns on the concrete hardening body obtained by hardening | curing this hydraulic blast furnace slag composition.

Binder: 40-80 mass% of ground granulated blast furnace slag having a fineness of 3000-8000 cm ² / g, 15-55 mass% of Portland cement and 1.0-5.0 mass% of sulfate in terms of SO ₃ ( The total content of blast furnace slag fine powder, Portland cement and sulfate is 100% by mass).

  Strength enhancer: Water-soluble dextrin compound having a mass average molecular weight of 1000 to 20000 and a solubility in water of 21 ° C. of 90% or more

  The admixture used for the hydraulic blast furnace slag composition (hereinafter referred to as the composition of the present invention) according to the present invention includes, as part thereof, an aqueous solution having a mass average molecular weight of 1000 to 20000 and a solubility in water of 21 ° C. of 90% or more. It contains a strength enhancer composed of a functional dextrin compound.

  A dextrin compound is a generic term for plant-derived high molecular weight compounds obtained by hydrolyzing starch with an enzyme such as amylase or an acid. In order to prevent cracking due to heat of hydration in a thick concrete hardened body, a technique using a specific dextrin has already been proposed (see, for example, Patent Documents 2 to 8 above). In the process where the temperature of a concrete member (for example, a thick wall) rises due to heat of hydration and decreases to the outside temperature again, if this member is constrained by another member (for example, a bottom plate), conceptually the following A tensile stress as shown in Equation 1 is generated, leading to cracking.

In Equation 1,
σ: Tensile stress R: Restraint degree T: Temperature rise α: Linear expansion coefficient E ₁ : Average Young's modulus during temperature rise E ₂ : Average Young's modulus during temperature drop (E ₂ >> E ₁ )

  In order to prevent cracks in the hardened concrete body, it is most effective to suppress the temperature rise. Therefore, for example, Patent Document 2 shows that a dextrin having a solubility at room temperature of 10 to 50% by mass and a solubility at a temperature of 60 ° C. of 50 to 100% by mass effectively suppresses the temperature rise. This is a technique focused on leaving dextrin that delays the reaction of cement and suppresses temperature rise until high temperatures. However, even if this technique is effective in suppressing the rise in temperature, there is a problem that the setting of the cement becomes too slow and the compressive strength of the obtained concrete hardened body is lowered.

  On the other hand, as a result of studying the effect of various dextrins on the compressive strength of a hardened concrete body obtained from a hydraulic blast furnace slag composition, the present inventors have found that dextrin (21 ° C. solubility is soluble in water at room temperature). It has been found that 90% or more of dextrin) can simultaneously and sufficiently solve the problems 1) and 2) according to the molecular weight. That is, a water-soluble dextrin having a mass average molecular weight in the range of 1000 to 20000 can simultaneously and sufficiently solve the above problems 1) and 2). The reason why such an effect is exhibited is not necessarily clear, but it is presumed that the water-soluble dextrin compound suppresses slag reaction inhibition by the hydrated product.

  The strength enhancer used as a part of the admixture used in the composition of the present invention is a water-soluble dextrin compound having a solubility in water at 21 ° C. of 90% or more, preferably having a mass average molecular weight of 1000 to 20000, preferably A mass average molecular weight is 2000-10000. In the present invention, the mass average molecular weight of the dextrin compound is a polyethylene glycol equivalent mass average molecular weight measured by an aqueous GPC method (gel permeation chromatography, the same applies hereinafter). Such a dextrin compound preferably has a dispersity (ratio of mass average molecular weight Mw / number average molecular weight Mn) in the molecular weight distribution curve measured by GPC method of 1.2 to 6.0. When the degree of dispersion is larger than this range, the strength enhancement effect intended by the present invention tends to decrease. Such a dextrin compound having a low degree of dispersion itself is produced by a known method (for example, the method described in JP-A-2008-222822), and is usually supplied as a powder product for uses such as food additives. .

  The aforementioned strength enhancer used as part of the admixture enhances both the compressive strength of the standard underwater curing specimen and the compressive strength of the high temperature hysteretic structure.

  In the composition of the present invention, the content of the strength enhancer used as a part of the admixture is usually 0.01 to 0.50 parts by mass per 100 parts by mass of the binder, but 0.02 to 0. The ratio is preferably 40 parts by mass. When the content is higher than these ratios, the setting delay is increased, and there is a problem that the obtained hardened concrete becomes hardened at the initial age. Conversely, when the content is low, the intended effect of the present invention is obtained. I can't.

  The admixture used for the composition of the present invention can further contain a cement dispersant as a part of the strength enhancer. As such a cement dispersant, conventionally known ones such as lignin sulfonate, naphthalene sulfonate formalin high condensate salt, polycarboxylic acid-based water-soluble vinyl copolymer, etc. can be used. A preferred vinyl copolymer is preferred.

  Water-soluble vinyl copolymer: 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 100 mol%) ), A water-soluble vinyl copolymer having a mass average molecular weight of 2000 to 80000.

  Structural unit X: one or two or more selected from structural units formed from methacrylic acid and structural units 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: one or two or more selected from a structural unit formed from (meth) allyl sulfonate and a structural unit formed from methyl (meth) acrylate

  In the composition of the present invention, the content of the water-soluble vinyl copolymer used as a part of the admixture is usually 0.1 to 1.0 part by mass per 100 parts by mass of the binder.

  In the composition of the present invention, a high-blast furnace slag-containing binder having a high content of fine blast furnace slag powder is used as the binder. In general, a concrete composition prepared using a binder containing a high content of blast furnace slag is more fluid than a concrete composition prepared using blast furnace cement or Portland cement with a low content of blast furnace slag fine powder as a binder. The decline is great. In order to ensure on-site enforcement, the concrete composition prepared using a high blast furnace slag-containing binder as a binder like the composition of the present invention includes a fluidity retention agent in addition to a cement dispersant. Although it is necessary to use, in the composition of the present invention, the above-mentioned water-soluble dextrin compound used as a strength enhancer is used as a fluidity retention agent for the above-mentioned water-soluble vinyl copolymer used as a cement dispersant. Also functions and prevents the fluidity of the prepared composition of the present invention from decreasing.

  In the composition of the present invention, when a strength enhancer and a water-soluble vinyl copolymer are used as an admixture, they are preferably mixed in advance and used as a one-component admixture. In this case, the admixture preferably contains 20-80% by weight of the strength enhancer and 80-20% by weight (total 100% by weight) of the water-soluble vinyl copolymer. It is more preferable to contain 35-65 mass% and 65-35 mass% (total 100 mass%) of a water-soluble vinyl copolymer. Such a one-component admixture is preferably used in a proportion of 0.12 to 1.4 parts by mass, and used in a proportion of 0.2 to 1.0 parts by mass per 100 parts by mass of the binder. Is more preferable.

The binder used for the composition of the present invention is 40 to 80% by mass of fine powder of blast furnace slag having a fineness of 3000 to 8000 cm ² / g, 15 to 55% by mass of Portland cement, and 1.3 in terms of SO _{3 in} terms of SO ₃ . 0 to 5.0% by mass (a total of 100% by mass of blast furnace slag fine powder, Portland cement and sulfate), preferably 60 to 70% by mass of fine blast furnace slag powder, Portland cement 26 to 36% by mass and sulfate in an amount of 1.5 to 4.0% by mass in terms of SO ₃ (100% by mass in total of fine blast furnace slag powder, Portland cement and sulfate). . As a mixture of ordinary Portland cement and blast furnace slag fine powder, there is a blast furnace cement that satisfies JIS standards. Depending on the amount of blast furnace slag fine powder, blast furnace cement is classified into blast furnace cement type A (over 5% by mass to 30% by mass), blast furnace cement type B (over 30% by mass to 60% by mass), and blast furnace cement C type (60% by mass). (Over 70 mass%). The binder used in the composition of the present invention is not particularly limited as long as it is described above, and blast furnace cement type B and blast furnace cement type C satisfying JIS standards can be used, and in particular, blast furnace slag. Blast furnace cement type C with the largest amount of fine powder can be used.

In addition to the above-mentioned blast furnace slag fine powder, Portland cement and sulfate, the binder used in the composition of the present invention may be used in combination with limestone fine powder, fly ash, silica fume, etc. for the purpose of improving its performance. it can. Among them, limestone fine powder having a fineness of 3000 to 12000 cm ² / g and a CaCO ₃ content of 70% by mass or more is preferably 3 to 20% by mass in the binder, and preferably 5 to 15% by mass. The combined use improves the fluidity of the prepared hydraulic blast furnace slag composition and the compressive strength of the resulting concrete cured body.

  Examples of the fine aggregate used in the composition of the present invention include known river sand, crushed sand, mountain sand and the like, and examples of the coarse aggregate include known river gravel, crushed stone, lightweight aggregate and the like.

  The composition of the present invention can be used in combination with other admixtures as necessary. Examples of such other admixtures include AE water reducing agents, high performance AE water reducing agents, AE agents, antifoaming agents, waterproofing agents, preservatives, and rustproofing agents.

  The composition of the present invention can be prepared by kneading the binder, water, fine aggregate, coarse aggregate and admixture described above by a known method. Specifically, a binder, a part of water, fine aggregate and coarse aggregate are kneaded with a mixer, while the above-mentioned admixture, and further, a cement dispersant and an AE regulator are added to the remainder of the water. It can be prepared by diluting with 1 to form a one-component admixture and then kneading both. In this case, the above-mentioned admixture is prepared by dissolving a dextrin compound, which is usually supplied as a powder, in advance in a part of water at room temperature to obtain a 10-50 mass% aqueous solution of dextrin. It is preferable in terms of improving the performance.

  According to the present invention, even when using a binder containing a high content of blast furnace slag, the compressive strength of the resulting hardened concrete is increased and the compressive strength of the hardened concrete obtained even when subjected to a high temperature thermal history Exhibits an excellent effect of improving

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

Test Category 1 (Preparation of admixture)
-Preparation of Strength Enhancer Among many dextrin compounds distributed as food additives, molecular weight and dispersion degree were measured by GPC method, and various dextrin compounds having different molecular weight and dispersion degree were prepared. Among them, dextrin compounds corresponding to strength enhancers were selected, and 30% aqueous solutions thereof were prepared. The contents of the selected dextrin compounds are summarized in Table 1.

In Table 1,
Molecular weight: Mass average molecular weight or number average molecular weight in terms of polyethylene glycol by GPC method Dispersity: Numerical value obtained by dividing mass average molecular weight (Mw) by number average molecular weight (Mn)

Synthesis of water-soluble vinyl copolymer 60 g of methacrylic acid, methoxypoly (23 oxyethylene units, hereinafter referred to as n = 23) ethylene glycol methacrylate 300 g, sodium methallylsulfonate 5 g, 3-mercaptopropionic acid 3 g and After 490 g of water was charged into the reaction vessel, 58 g of a 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 (b-1). When the water-soluble vinyl copolymer (b-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 (b-1) having a mass average molecular weight of 34200 (GPC method, converted to polyethylene glycol) having a ratio of 70/27/3 (mol%). Similarly, 40% water solubility of water-soluble vinyl copolymers (b-2) to (b-3) and (br-1) to (br-3) was obtained. The contents of the water-soluble vinyl copolymer synthesized above are summarized in Table 2.

In Table 2,
Mass average molecular weight: GPC method, converted into polyethylene glycol X-1: Structural unit formed from sodium methacrylate X-2: Structural unit formed from methacrylic acid Y-1: Formed from methoxypoly (23 mol) ethylene glycol methacrylate Structural unit Y-2: Structural unit formed from methoxypoly (70 mol) ethylene glycol methacrylate Z-1: Structural unit formed from sodium methallyl sulfonate Z-2: Structural unit formed from sodium allyl sulfonate Z-3: a structural unit formed from methyl acrylate

-Preparation of one-component admixture An aqueous solution of the above dextrin compound, an aqueous solution of a water-soluble vinyl copolymer, and water are mixed at a predetermined ratio, and one-component admixtures (P-1) to (P-10) are mixed. A 30% aqueous solution of was prepared. Similarly, 30% aqueous solutions of one-component admixtures (R-1) to (R-10) were prepared. Table 3 summarizes the contents of the admixture in each of the prepared aqueous solutions.

In Table 3,
Dextrin compound: dextrin compound listed in Table 1 water-soluble vinyl copolymer: water-soluble vinyl copolymer listed in Table 2 * 1: tannic acid * 2: starch * 3: glucose

Test category 2 (Preparation of binder)
Under the blending conditions shown in Table 4, a binder was prepared using blast furnace slag fine powder, anhydrous gypsum, ordinary Portland cement, and limestone fine powder to obtain binders (sb-1) to (sb-3).

In Table 4,
sg-1: Blast furnace slag fine powder having a fineness of 6150 cm ² / g and a density of 3.01 g / cm ³ sg-2: Blast furnace slag fine powder having a fineness of 4100 cm ² / g and a density of 3.04 g / cm ³ gp-1: anhydrous gypsum having a fineness of 4080 cm ² / g and a density of 3.01 g / cm ³ pc-1: ordinary Portland cement limestone fine powder: fineness of 5500 cm ² / g and CaCO ₃ content of 97% by mass Limestone fine powder

Test category 3 (Preparation and evaluation of hydraulic blast furnace slag composition, etc.)
Examples 1 to 20 and Comparative Examples 1 to 21 (Preparation of hydraulic blast furnace slag composition)
Under the blending conditions shown in Table 5, a 50-liter pan-type forced kneader mixer was combined with a binder, fine aggregate, tap water, an AE water reducing agent (trade name Tupol EX50 manufactured by Takemoto Yushi Co., Ltd.), and an AE regulator (Takemoto). Predetermined amounts of 30% aqueous solutions of admixtures listed in Table 3 (trade name AE300 manufactured by Yushi Co., Ltd.) and Table 3 were added in order and kneaded until a uniform slurry was obtained. Next, the coarse aggregate was added and kneaded for 30 seconds, and the hydraulic properties of Examples 1 to 20 and Comparative Examples 1 to 21 in which the target slump was 18 ± 1 cm and the target air amount was 4.5 ± 0.5%. A blast furnace slag composition and the like were prepared. The temperature at the time of kneading was 30 ° C in all cases. Tables 6 and 7 collectively show the contents of the prepared hydraulic blast furnace slag composition and the like of each example.

In Table 5,
sb-1 to sb-3: binders described in Table 4 Fine aggregate: Oikawa water sand, density is 2.58 g / cm ³
Coarse aggregate: Okazaki crushed stone, density 2.68 g / cm ³

・ Evaluation of prepared hydraulic blast furnace slag composition, etc.For the prepared hydraulic blast furnace slag composition, etc., the slump, air volume, compression strength of standard underwater curing specimen and compressive strength of high temperature history specimen are as follows: Asked. The results are summarized in Table 6 and Table 7.

-Slump (cm): It measured according to JIS-A1101 about the hydraulic blast furnace slag composition etc. immediately after kneading | mixing and after leaving still for 60 minutes.
-Air amount (volume%): It measured based on JIS-A1128 about the hydraulic blast furnace slag composition etc. immediately after kneading | mixing and after leaving still for 60 minutes.
Compressive strength (N / mm ² ) of standard water curing specimen: Filled with a cylindrical mold having a diameter of 10 cm and a height of 20 cm in each case with a hydraulic blast furnace slag composition of each example prepared by mixing, The specimens cured underwater until the age of 7 or 28 days were measured according to JIS-A1108.
Compressive strength (N / mm ² ) of high-temperature history specimen: Nine pieces of hydraulic blast furnace slag compositions, etc., prepared by kneading each in a cylindrical mold having a diameter of 10 cm and a height of 20 cm were prepared. Inside the heat insulation box with inner dimensions of 500mm x 500mm x 400mm and six surrounding surfaces covered with a heat insulation material (foamed styrene) with a thickness of about 30cm, the nine above are arranged in parallel at equal intervals of 3 vertical x 3 horizontal It left still, the thermocouple was installed in one of the center positions, and the temperature rise history inside was measured (maximum exothermic temperature 40-60 degreeC). The compressive strength was measured in accordance with JIS-A1108 for the high temperature history specimen in which the high temperature history load was continued until the age of 28 days.

In Table 6 and Table 7,
Compounding conditions: Compounding conditions described in Table 5 Types of admixture: Types of admixture described in Table 3 Amount of admixture used: part by mass of admixture added to 100 parts by mass of the binder.
* 4: Comparative example (admixture R-1 in Table 3 was used) in which the admixture with the corresponding blending condition was not used from the compressive strength (age 7 days or 28 days) of the standard water curing specimen of each example. Value obtained by subtracting the compressive strength (material age 7 days or 28 days) of the standard underwater curing specimen of Comparative Example 1, 11 or 21) * 5: Compressive strength of the high temperature history specimens of each example (material age 28 days) Is subtracted from the compressive strength (material age 28 days) of the high temperature history specimen of Comparative Example (Comparative Example 1, 11 or 21 using Admixture R-1 in Table 3) that did not use the admixture of the corresponding blending conditions. Value

  As is clear from the results of Tables 6 and 7, the hydraulic blast furnace slag composition of each example has a higher compressive strength than the hydraulic blast furnace slag composition of each comparative example. In addition, the effect of increasing the compressive strength is high even after high temperature history. According to this invention, the problem at the time of using a blast furnace slag high content binder can be improved simultaneously and fully.

Claims (8)

A hydraulic blast furnace slag composition containing the following binder, water, fine aggregate, coarse aggregate, and an admixture, wherein the following strength enhancer is added as a part of the admixture to an amount of 0. A hydraulic blast furnace slag composition, which is contained at a ratio of 01 to 0.50 parts by mass.
Binder: 40-80 mass% of ground granulated blast furnace slag having a fineness of 3000-8000 cm ² / g, 15-55 mass% of Portland cement and 1.0-5.0 mass% of sulfate in terms of SO ₃ ( The total content of blast furnace slag fine powder, Portland cement and sulfate is 100% by mass).
Strength enhancer: Water-soluble dextrin compound having a mass average molecular weight of 1000 to 20000 and a solubility in water of 21 ° C. of 90% or more   The hydraulic blast furnace slag according to claim 1, wherein the strength enhancer is a water-soluble dextrin compound having a mass average molecular weight of 2000 to 10,000, a dispersity of 1.2 to 6.0, and a solubility in water of 21 ° C of 90% or more. Composition.   The hydraulic blast furnace slag composition according to claim 1 or 2, wherein the strength enhancer is contained at a ratio of 0.02 to 0.40 parts by mass per 100 parts by mass of the binder. The water-soluble vinyl copolymer below as a part of the admixture is further contained at a ratio of 0.1 to 1.0 part by mass per 100 parts by mass of the binder. Hydraulic blast furnace slag composition.
Water-soluble vinyl copolymer: 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 100 mol%) ), A water-soluble vinyl copolymer having a mass average molecular weight of 2000 to 80000.
Structural unit X: One or more selected from a structural unit formed from methacrylic acid and a structural unit formed from methacrylic acid salt. Structural unit Y: composed of 7 to 150 oxyethylene units in the molecule. Structural unit formed from methoxypolyethylene glycol methacrylate having a polyoxyethylene group Structural unit Z: one selected from a structural unit formed from (meth) allyl sulfonate and a structural unit formed from methyl (meth) acrylate Or two or more   The admixture contains 20 to 80% by mass of the strength enhancer and 80 to 20% by mass (total 100% by mass) of the water-soluble vinyl copolymer, and 100 parts by mass of the admixture is added to the admixture. The hydraulic blast furnace slag composition according to claim 4, which is contained at a ratio of 0.12 to 1.4 parts by mass per unit.   The binder is 60 to 70% by mass of blast furnace slag fine powder, 26 to 36% by mass of Portland cement, and 1.5 to 4.0% by mass of sulfate in terms of SO3 (blast furnace slag fine powder, Portland cement and sulfate The hydraulic blast furnace slag composition according to any one of claims 1 to 5, wherein the hydraulic blast furnace slag composition according to any one of claims 1 to 5 is contained. The hydraulic blast furnace slag composition according to claim 1, wherein the binder further contains the following limestone fine powder in the binder so as to be 3 to 20 mass%.
Limestone fine powder: Limestone fine powder having a fineness of 3000 to 12000 cm ² / g and a CaCO ₃ content of 70% by mass or more.   A hardened concrete body obtained by curing the hydraulic blast furnace slag composition according to any one of claims 1 to 7.