JP6281365B2 - Low grade blast furnace slag mixed cement composition and method for producing the same - Google Patents

Description

  The present invention relates to a low-grade blast furnace slag mixed cement composition that is excellent in strength development even when a blast furnace slag having a basicity outside the JIS standard is used, and a method for producing the same.

Various industrial wastes and / or by-products are used in the cement industry. By effectively using industrial waste and by-products as resources, it is possible to contribute to a recycling-oriented society and reduce carbon dioxide (CO ₂ ) emissions.

A typical by-product is blast furnace slag, which is widely used as a mixture for cement compositions. As one of the indexes for determining the activity, the basicity calculated from (CaO + Al ₂ O ₃ + MgO) / SiO ₂ is used, and it is generally considered that the higher basicity is better. JIS R 5211 : 2009 "Blast Furnace Cement" defines the basicity of blast furnace slag used for cement as 1.6 or more. For example, Patent Document 1 discloses a cement composition that can obtain a strength equivalent to that of ordinary cement by using a specific cement type and a blast furnace slag powder having a high Blaine specific surface area.

  On the other hand, from the viewpoint of further contribution to a recycling-oriented society and reduction of carbon dioxide emissions, it is also necessary to effectively use blast furnace slag having a basicity lower than that of the current JIS standard. As an example using such a low basicity blast furnace slag powder, Patent Document 2 discloses a blast furnace granulated slag having a basicity of 1.85 to 2.00 and basicity for the purpose of producing a low exothermic cement. In combination with rock wool or rock wool waste slag starting from blast furnace slag of about 1.25 to 1.45, a mixed powder adjusted to a basicity of 1.4 to 1.8 was used. A method for producing a low exothermic slag cement is disclosed.

JP 2012-254909 A JP-A-10-87352

  However, in order to use it for general purposes such as ordinary Portland cement and blast furnace cement, it is required to have excellent strength development.

  Therefore, an object of the present invention is to provide a low-grade blast furnace slag mixed cement composition having excellent strength development and a method for producing the same even when blast furnace slag having a basicity outside the JIS standard is used.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have achieved a high strength expression even when the basicity of the blast furnace slag is lower than the JIS standard by setting a specific amount of blast furnace slag. In addition, the present inventors have found that a cement composition can be obtained in which the increase in heat insulation temperature is comparable, and the present invention has been completed.

  That is, the present invention is a low-grade blast furnace slag mixed cement composition comprising a cement composition comprising cement clinker and gypsum and blast furnace slag, wherein the basicity of the blast furnace slag is 1.4 or more and less than 1.6. Further, the present invention relates to a low-grade blast furnace slag mixed cement composition having a content of the blast furnace slag of more than 1% by mass and 15% by mass or less. By setting the basicity and content of the blast furnace slag within these ranges, even if the basicity is lower than the JIS standard, excellent strength development can be obtained, and an increase in the adiabatic temperature can be suppressed.

Further, according to the present invention, the C ₃ A content of the cement composition is 9.0 to 13.5% by mass, the HM of the cement composition is 2.00 to 2.20, and the SM is 2.00. The present invention relates to a low-grade blast furnace slag cement composition having an IM of 2.55 to 2.40. By making the mineral composition and the various ratios within these ranges, it is possible to obtain even more excellent strength development properties and to suppress an increase in the adiabatic temperature.

Low-grade blast furnace slag mixed cement composition having a C ₃ S content of 45 to 55% by mass, a C ₂ S content of 20 to 28% by mass, and a C ₄ AF content of 8 to 14% by mass. About. By setting it as these ranges, fluidity | liquidity and intensity | strength expression are still more favorable and the heat insulation temperature rise can also be suppressed.

MgO content of from 0.80 to 1.10 wt% of the cement composition, SO ₃ content of 1.80 to 2.30 wt%, Na ₂ O content of 0.10 to 0.30 mass%, K _It is related with the low grade blast furnace slag mixing cement composition whose 2O content is 0.20-0.40 mass% and f.CaO content is 0.40-0.70 mass%. By setting it as these ranges, fluidity | liquidity and intensity | strength expression are still more favorable and the heat insulation temperature rise can also be suppressed.

Moreover, this invention relates to the low grade blast furnace slag mixing cement composition whose brane specific surface area is 3000-4000 cm < ² > / g. By making the brane specific surface area of the cement composition within these ranges, it is possible to obtain even more excellent strength development and to suppress an increase in the adiabatic temperature.

The present invention also relates to a low-grade blast furnace slag cement composition in which the blast furnace slag has a Blaine specific surface area of 2600 to 4600 cm ² / g. By setting the Blaine specific surface area of the blast furnace slag within these ranges, even more excellent strength development can be obtained, and an increase in the adiabatic temperature can be suppressed.

  Further, the present invention provides a cement clinker, gypsum, and blast furnace slag having a basicity of 1.4 or more and less than 1.6 so that the content of the blast furnace slag is more than 1% by mass and 15% by mass or less. It is related with the manufacturing method of the low quality blast furnace slag mixing cement composition including the process of mixing and preparing the said low quality blast furnace slag mixing cement composition. By setting the basicity and content of the blast furnace slag within these ranges, a cement composition in which excellent strength development is obtained and adiabatic temperature rise is suppressed even when the basicity is lower than JIS standards. It can be manufactured.

  According to the present invention, even when blast furnace slag whose basicity is outside the JIS standard is used, it is possible to obtain a cement composition that is excellent in strength development and can suppress an increase in adiabatic temperature.

  The present invention is described in detail below.

  The low-grade blast furnace slag mixed cement composition of the present invention includes a cement composition made of cement clinker and gypsum, and blast furnace slag.

  The basicity of the blast furnace slag is 1.4 or more and less than 1.6, preferably 1.45 or more and less than 1.56, and more preferably 1.50 or more and less than 1.53. Within these ranges, strength development is good.

The blast furnace slag has a brain specific surface area of 2600 to 4600 cm ² / g, preferably 3200 to 4400 cm ² / g, and more preferably 3800 to 4200 cm ² / g. If it is these ranges, intensity | strength expression will be favorable and the heat insulation temperature raise can also be suppressed.

  The low-grade blast furnace slag mixed cement composition contains blast furnace slag more than 1 mass% and 15 mass% or less, preferably more than 5 mass% and 13 mass% or less, more preferably more than 9 mass% and 11 mass% or less. If it is these ranges, intensity | strength expression will be favorable and the heat insulation temperature raise can also be suppressed.

The low grade blast furnace slag mixed cement composition contains 82 to 93% by mass of cement clinker, preferably 86.0 to 92% by mass, and more preferably 89 to 91% by mass. Further, gypsum is contained in an amount of 1.0 to 3.0% by mass, preferably 1.5 to 2.5% by mass, and more preferably 1.8 to 2.2% by mass based on SO ₃ . If it is these ranges, fluidity | liquidity and intensity | strength expression will be favorable and can also suppress adiabatic temperature rise.

The mineral composition of the cement composition composed of cement clinker and gypsum has a C ₃ A amount of 9.0 to 13.5% by mass, preferably 9.5 to 13.25% by mass, and more preferably 11 on the basis of the Borg formula. It is 0.0-13.0 mass%. When the amount of C ₃ A exceeds 13.5% by mass, the heat of hydration increases and the fluidity also decreases, which is not preferable.
Also, _{C 3} S content of 45 to 55 wt%, preferably from 47 to 53 wt%, more preferably 49-51 wt%. Also, _{C 2} S content of 20 to 28 wt%, preferably from 21 to 26 wt%, more preferably 22-25 wt%. _{Moreover, C} 4 AF content of 8-14 wt%, preferably 9-13 wt%, more preferably 9.5 to 12.8 wt%. If it is these ranges, fluidity | liquidity and intensity | strength expression will be favorable and can also suppress adiabatic temperature rise.

  The HM of the cement composition is 2.00 to 2.20, preferably 2.04 to 2.15, more preferably 2.06 to 2.12, and SM is 2.00 to 2.55, preferably 2. .10 to 2.52, more preferably 2.12 to 2.50, and IM is 1.75 to 2.40, preferably 1.78 to 2.3, more preferably 1.80 to 2.25. It is. Within these ranges, fluidity and strength development are good.

Blaine specific surface area of the low-grade blast furnace slag blended cement composition 3000~4000cm ² / g, preferably from 3200~3600cm ² / g, more preferably 3300~3400cm ² / g. If it is these ranges, intensity | strength expression will be favorable and the heat insulation temperature raise can also be suppressed.

Total alkali content of the cement composition _(R 2 O) is 0.25 to 0.80 wt%, preferably from 0.30 to 0.60 wt%, more preferably from 0.33 to 0.5 wt% . When the total alkali amount exceeds 0.80% by mass, there is a concern about a decrease in fluidity, a decrease in strength development, and a decrease in durability due to an alkali aggregate reaction.
The MgO content is 0.80 to 1.10% by mass, preferably 0.90 to 1.05% by mass, and more preferably 0.92 to 0.98% by mass. The SO ₃ content is 1.80 to 2.30% by mass, preferably 1.90 to 2.20% by mass, and more preferably 1.95 to 2.15% by mass. Content of Na ₂ O is 0.10 to 0.30 wt%, preferably from 0.15 to 0.25 wt%, more preferably from 0.18 to 0.23 wt%. The K ₂ O content is 0.20 to 0.40% by mass, preferably 0.21 to 0.38% by mass, and more preferably 0.22 to 0.35% by mass. f. The CaO content is 0.40 to 0.70% by mass, preferably 0.50 to 0.65% by mass, and more preferably 0.55 to 0.63% by mass. If it is these ranges, intensity | strength expression will be favorable and the heat insulation temperature raise can also be suppressed.

Cement clinker is mixed with one or more materials selected from the group consisting of limestone, silica, coal ash, clay, blast furnace slag, construction generated soil, sewage sludge, blast furnace dust, copper tangled, deiron slag, and incinerated ash, and calcined. To do.
By using relatively large amounts of industrial waste and / or by-products such as blast furnace slag and coal ash, the amount of limestone and meteorite, which are natural resources, can be reduced and energy consumption can be reduced. It is possible to reduce CO ₂ emissions resulting from limestone pyrolysis and fuel combustion.

  The cement clinker can be fired using an existing cement manufacturing facility such as the SP system (multistage cyclone preheating system) or the NSP system (multistage cyclone preheating system equipped with a calcining furnace).

  It is desirable that the gypsum satisfies the quality specified in JIS R 9151 “natural gypsum for cement”. Specifically, dihydrate gypsum, hemihydrate gypsum, and insoluble anhydrous gypsum are suitably used for the cement composition.

  As a method for producing a low-grade blast furnace slag mixed cement composition, a method in which cement clinker, gypsum and blast furnace slag are pulverized and mixed at the same time, a cement clinker and gypsum are crushed to produce a cement composition, and then pulverized. Examples thereof include a method of mixing with blast furnace slag, a method of pulverizing cement clinker and gypsum to produce a cement composition, and then mixing and pulverizing with unground blast furnace slag.

  The contents of the present invention will be described in detail below with reference to examples and comparative examples. Note that the present invention is not limited to these examples.

[1. Blast furnace slag]
As shown in Table 1, JIS R 5211: 2009 “Blast Furnace Cement” standard products and basicity non-standard products were used in total. The chemical composition of the blast furnace slag was measured by JIS R 5202 “Chemical analysis method of Portland cement”. The brain specific surface area was measured using a brain air permeation apparatus in accordance with JIS R 5201 “Physical testing method for cement”. The basicity was calculated according to JIS R 5211: 2009 “Blast Furnace Cement”.

[2. Preparation of blast furnace slag mixed cement composition]
Table 2 and Table 3 show the cement characters used. To these cements, 10% by mass or 40% by mass of blast furnace slag was added internally to prepare a total of 7 levels of blast furnace slag mixed cement compositions shown in Table 4. The minor component in the cement was measured according to JIS R 5202: 1999 “Chemical analysis of Portland cement”. f. The amount of CaO was measured according to JCAS I-01: 1997 “Method for Quantifying Free Calcium Oxide” of the Cement Association Standard Test Method. The mineral composition of the cement was calculated by the following Borg equation. C represents CaO, S represents SiO ₂ , A represents Al ₂ O ₃ , and F represents Fe ₂ O ₃ .

_{C 3 S = 4.07 × (CaO} -f.CaO) -7.60 × SiO 2 -6.72 × Al 2 O 3 -1.43 × Fe 2 O 3
_{C 2 S = 2.87 × SiO 2} -0.75 × C 3 S
C ₃ A = 2.65 × Al ₂ O ₃ −1.69 × Fe ₂ O ₃
C ₄ AF = 3.04 × Fe ₂ O ₃

[3. Preparation of mortar specimen and evaluation of compressive strength]
According to JIS R 5201: 1998 “Physical Test Method for Cement”, preparation of a mortar specimen and measurement of compressive strength were performed. Table 5 shows the measurement results of the compressive strength.

  From Table 5, the mortar compressive strength of the cement composition (Comparative Examples 1 and 2) added with 40% of blast furnace slag whose basicity is not JIS standard is the standard cement composition (reference) using JIS standard blast furnace slag. It was lower than Example 1). On the other hand, the products of the present invention (Examples 1 and 2) in which the addition rate was 10% by mass even for non-JIS products exhibited the same compressive strength as the JIS standards (Reference Examples 2 and 3).

[4. Measurement of adiabatic temperature rise]
Using adiabatic calorimeter for small amount mortar shown in Japanese Patent Application Laid-Open No. 2008-241520, based on the concrete composition shown in Table 6, published literature (Mariya Eiji et al .: Development of cement quality control technique using adiabatic calorimeter for small sample , Cement / Concrete Papers, No. 61, pp. 86-92 (2007)).

The amount of heat insulation temperature rise was evaluated by applying the measurement result to Equation (1), which is a regression equation of heat insulation temperature rise proposed by the Japan Concrete Institute.
Q (t) = Q _∞ (1-exp (-γ (tt ₀ ))) ··· Equation (1)
Q (t): Adiabatic temperature rise (° C), Q _∞ : Ultimate adiabatic temperature rise (° C), t: Age (d), t ₀ : Age at which heat generation starts (d), γ: Rate of temperature rise Constants

  Table 7 shows the results of the adiabatic temperature rise.

  From the results of Table 7, the amount of heat insulation temperature rise of the cement composition (Example 2) using low basicity blast furnace slag is the same as that of the cement composition (Reference Example 3) using JIS standard blast furnace slag. It turns out that they are equivalent.

  As described above, according to the present invention, even when a blast furnace slag having a basicity outside the JIS standard is used, a cement composition having no problem in strength development and adiabatic temperature rise characteristics is obtained. be able to.

Claims (7)

A low-grade blast furnace slag mixed cement composition comprising a cement composition comprising cement clinker and gypsum and blast furnace slag,
The basicity of the blast furnace slag is less than 1.4 and 1.6, and state, and are 15 wt% or less than the content of 5 wt% of the blast furnace slag,
The cement composition has an HM of 2.00 to 2.20, an SM of 2.00 to 2.55 and an IM of 1.75 to 2.40;
The blast furnace slag has a brain specific surface area of 2600 to 4600 cm ² / g,
The low-grade blast furnace slag Blaine specific surface area of the mixed cement composition, characterized in 3000~4000cm ² / g Der Rukoto low grade blast furnace slag blended cement compositions. The _{C 3} A content of 9.0 to 13.5% by weight of the cement _{composition, C} 4 AF content is 8 to 14 wt%, claim 1 low grade blast furnace slag blended cement composition. _{C 3} S content of 45 to 55 wt% of the cement composition, _{C 2} S content of 20 to 28 wt%, according to claim 1 or 2 low grade blast furnace slag blended cement composition. The low-grade blast furnace slag mixed cement composition according to any one of claims 1 to 3, wherein the low-grade blast furnace slag mixed cement composition has a Blaine specific surface area of 3200 to 3600 cm ² / g . The low-grade blast furnace slag mixing cement composition according to any one of claims 1 to 4, wherein the blast furnace slag has a brain specific surface area of 3200 to 4400 cm ² / g . The MgO content of the cement composition is 0.80 to 1.10% by mass, the SO ₃ content is 1.80 to 2.30% by mass, the Na ₂ O content is 0.10 to 0.30% by mass, the content of K ₂ O is 0.20-0.40% by weight and f.CaO content is 0.40 to 0.70 mass%, low-grade blast furnace slag according to any one of claims 1 to 5 Mixed cement composition. Cement clinker, gypsum, and blast furnace slag having a basicity of 1.4 or more and less than 1.6 are mixed so that the content of the blast furnace slag is more than 5 % by mass and 15% by mass or less. A method for producing a low-grade blast furnace slag mixed cement composition, comprising the step of preparing the low-grade blast furnace slag mixed cement composition according to any one of -6.