Composition containing binder, aggregate and water

Abstract

While ensuring a certain level of compressive strength, it aims to reduce drying shrinkage distortion and heat generation. The composition includes a binder, slag fine aggregate with a water absorption rate of 1.5% or more, and water. The binder contains an expansive agent and at least one selected from the group consisting of portland cement, blast furnace slag, fly ash, and silica fume. The unit water content is 100 kg / m. 3 More than 140kg / m 3 Hereinafter, the water-binder ratio is 20% or more and 40% or less.

Description

[Technical Field]

[0001] The present invention relates to a composition comprising a binder, an aggregate, and water. [Background technology]

[0002] Compositions containing binder, aggregate, and water (e.g., mortar, concrete) are required to have various properties depending on their application. For example, they may be required to reduce drying shrinkage strain and heat generation while maintaining a certain compressive strength. These properties are sometimes required for, for example, floor slab fill concrete. Patent Documents 1 and 2 disclose cementitious compositions and concrete compositions designed to reduce drying shrinkage strain and heat generation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Retable No. 2014-030610 [Patent Document 2] Patent Application No. 2019-043816 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention aims to provide a composition containing a binder, aggregate, and water that is different from the above and that can reduce drying shrinkage and heat generation while maintaining a certain compressive strength. [Means for solving the problem]

[0005] The composition of the present invention containing a binder, aggregate, and water comprises the binder, slag fine aggregate with a water absorption rate of 1.5% or more, and water, wherein the binder contains an expansive agent and at least one selected from the group consisting of Portland cement, blast furnace slag, fly ash, and silica fume, and the unit water content is 100 kg / m 3 More than 140kg / m 3 Hereinafter, the water-binder ratio is 20% or more and 40% or less. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a composition containing a binder, aggregate, and water that can reduce drying shrinkage strain and heat generation while ensuring a certain level of compressive strength. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a graph showing the compressive strength of an example and a comparative example. [Figure 2] 1 is a graph showing drying shrinkage strains of Examples and Comparative Examples. [Figure 3] 1 is a graph showing the heat generation characteristics of Example 1-2 and Comparative Example 1-5. [Example]

[0008] The present invention will be explained below with reference to examples. Table 1 shows the specifications of the materials used in the concrete compositions used in each example and comparative example, and Table 2 shows the mix proportions for each example and comparative example. Each example contains at least two binders selected from the group consisting of portland cement, expansive additive, blast furnace slag, fly ash, and silica fume. In the "mass ratio of binder" in Table 2, cement and expansive additive are treated as a single category (C+Ex). This is because cement and expansive additive have similar properties in terms of drying shrinkage strain and calorific value. Expansive additives are generally used in a unit amount of 20 kg / m 3 In order to mix about the amount of expansive material, the unit amount of expansive material was set to 20 kg / m in each example and comparative example (only comparative examples containing expansive material). 3 Figure 1 shows the compressive strength (standard water curing, material age 28 days) of each example and comparative example, and Figure 2 shows the drying shrinkage strain of each example and comparative example. Drying shrinkage strain was measured after 182 days (material age 189 days) when the test specimens were cured in water at 20°C until the material age of 7 days, and then placed in an environment of 20°C and 60% RH (relative humidity).

[0009] [Table 1]

[0010] [Table 2]

[0011] Comparative Examples 1-1 to 1-4 (collectively referred to as Comparative Example 1) have cement as a binder, and differ from one another in the presence or absence of an expansive agent and blast furnace slag, and in the type of fine aggregate. 2 The unit water content and water-binder ratio were larger than those of each Example. Comparative Example 1 was designed for concrete with a design strength of about 50 MPa, which is used for filling concrete in bridge decks, and the compressive strength was around 60 MPa. Since the concrete composition of the present invention does not require a high compressive strength, it is sufficient if the compressive strength is the same as that of the Comparative Example, or at least about 40 MPa.

[0012] Examples 1-1 to 1-5 (collectively referred to as Example 1) are concrete compositions comprising a binder, slag fine aggregate, coarse aggregate, chemical admixtures, and water. The binders consist of Portland cement, expansive additives, blast furnace slag, fly ash, and silica fume. Examples 1-1 to 1-5 differ in air content, type of coarse aggregate, and type of chemical admixture, but the type of binder is the same, and the unit amount of each binder, unit water amount, and water-to-binder ratio are approximately the same. The slag fine aggregate is air-crushed ferronickel slag fine aggregate (FNS fine aggregate). The air content, type of coarse aggregate, and type of chemical admixture have some effect on compressive strength and drying shrinkage strain, but these effects are smaller than those of the type and unit amount of binder, unit water amount, and water-to-binder ratio. All of Examples 1-1 to 1-5 have compressive strengths in the range of 60 to 86 MPa, which is within the compressive strength required by the present invention.

[0013] The drying shrinkage strain was reduced compared to the comparative example. This is likely due to the use of air-crushed FNS fine aggregate. Air-crushing is a process in which high-pressure air is blown onto molten slag, a by-product of ferronickel smelting, to separate it into fine spherical aggregates. The separated aggregates then fly through the air and collide with a wall. The hot aggregate cools as it flies through the air, eventually solidifying into spherical shapes. FNS fine aggregates produced in this manner can have relatively high water absorption. When this FNS fine aggregate is used in compositions containing aggregate, binder, and water, such as mortar and concrete, the absorbed water is released, which is thought to reduce drying shrinkage strain. The water absorption of the FNS fine aggregate in Example 1 is 2.70% (air-dry), but a slag fine aggregate with a water absorption of 1.5% (air-dry) or more is likely to have a similar effect.

[0014] Among Examples 2-1 to 2-7 (collectively referred to as Example 2), Examples 2-1 to 2-6 have the same unit water content and water-binder ratio as Examples 1-1 to 1-3, and the type of binder is also approximately the same as Example 1, but the cement amount (and therefore the ratio of C+Ex in the binder) is different from that of Example 1. Examples 2-1 and 2-2 have similar binder mass ratios to Example 1, and show similar trends in compressive strength and drying shrinkage strain to Example 1. Examples 2-3 to 2-6, which have a high ratio of C+Ex, show increased compressive strength and decreased drying shrinkage strain. Also, a tendency is observed where the higher the ratio of C+Ex, the greater the compressive strength and the smaller the drying shrinkage strain. Example 2-7 does not use cement, so its compressive strength is low, but its drying shrinkage strain is equivalent to that of Example 1.

[0015] In Examples 3-1 to 3-5 (collectively referred to as Example 3), the type and mass ratio of binder are the same as in Example 1, but the unit water content and water-binder ratio are different from those in Example 1. Example 3-4 has the same unit water content as Example 1 and a water-binder ratio close to that of Example 1, so both the compressive strength and drying shrinkage strain show similar trends to those in Example 1. As the unit water content and water-binder ratio decrease, the compressive strength increases and the drying shrinkage strain decreases. Conversely, as the unit water content and water-binder ratio increase, the compressive strength decreases and the drying shrinkage strain increases.

[0016] In Examples 4-1 to 4-3 (collectively referred to as Example 4), the type of binder, unit water content, and water binder were changed compared to Example 1. In Examples 4-1 to 4-3, fly ash was omitted from the binder composition of Example 1, and the fly ash was replaced with cement. Because the cement ratio was increased, the compressive strength increased and the drying shrinkage strain decreased compared to Examples 1 to 3.

[0017] In Example 5, the binder was only cement and expansive agent, and the unit water content and water-binder ratio were slightly increased compared to Example 1. The compressive strength showed a similar trend to Example 4, and the drying shrinkage strain was slightly higher than in Example 4.

[0018] Figure 3 shows the change over time in the amount of adiabatic temperature rise in Examples 1-2 and Comparative Example 2. Concrete solidifies while expanding due to heat generation, and internal stress is generated due to thermal deformation when it is subsequently cooled and contracts. Strain caused by this internal stress, along with drying shrinkage strain caused by evaporation of internal moisture, are major causes of cracks in concrete, so it is desirable to suppress both.

[0019] The temperature rise was calculated according to the method proposed in "Quantification of the heat generation process of hydration of cement present in concrete" (Suzuki Yasunori, Tsuji Yukikazu, Maekawa Koichi, Okamura Hajime, Journal of the Japan Society of Civil Engineers, No. 414, V-12, pp. 155-164, February 1990). Specifically, the temperature-dependent hydration heat generation rate equation, expressed as the following formula, was calculated based on the obtained data.

[0020]

number

[0021] where: H : Hydration heat generation rate of cement per unit weight Q: Total calorific value of cement per unit weight H∞ (Q): Critical hydration heat generation rate -E(Q) / R: Temperature activity of cement T: Temperature of concrete (absolute temperature) Each coefficient in (Equation 1) was determined by pouring sample concrete at three different temperatures into a φ150 x 300 mm tinplate formwork covered with 200 mm thick insulation, and measuring the outside air temperature, the temperature of the sample concrete, and the heat flux on the surface of the tinplate formwork. Figure 3 shows the adiabatic temperature rise calculated from (Equation 1) when the pouring temperature is set to 20°C. The cumulative heat generation Q can be calculated using the following equation. Q=cρΔT / C * (Formula 2) where: c: specific heat of concrete ρ: Density of concrete ΔT: Adiabatic temperature rise of concrete Q: Heat supply capacity of concrete C * : Unit cement amount (amount of cement per unit volume) The adiabatic temperature rise ΔT of concrete is the difference from the temperature of the concrete at the time of pouring. For example, if the temperature of the concrete when poured is 20°C, the temperature rise value ΔT of the concrete is calculated as the increment to 20°C. The adiabatic temperature rise value ΔT of concrete is obtained as a function of the elapsed time t from the start of measurement.

[0022] Referring to Figure 3, Example 1-2 exhibits a more limited temperature rise than Comparative Example 2. Comparative Example 2 uses only cement and expansive additive as binders (the mass ratio of C + Ex in the binder is 100%), whereas Example 1-2 further uses blast furnace slag, fly ash, and silica fume as binders, with the mass ratio of C + Ex in the binder being only 25%. The temperature rise is likely to be suppressed because the reaction heat generated by blast furnace slag, fly ash, and silica fume is smaller than the heat generated by the cement hydration reaction. Furthermore, although the water-binder ratio is reduced by reducing the unit water content, the suppression of the unit amount of C + Ex is also likely to have led to a suppression of the calorific value of the cement hydration. Examples 1 other than Example 1-2 (Examples 1-1, 1-3, 1-4, and 1-5) have the same binder mass ratio, unit water content, and water-binder ratio as Example 1-2, and are therefore expected to show similar trends to Example 1-2. Regarding Example 2, it is thought that examples with a small unit amount of C+Ex (e.g., Examples 2-1 and 2-2) will show a similar tendency to Example 1-2, while examples with a relatively large unit amount of C+Ex (e.g., Examples 2-3 to 2-6) will show results intermediate between Example 1-2 and Comparative Example 2. Regarding Example 3, the unit amount of C+Ex is about the same as in Example 1-2, so it is thought that the tendency will be similar to Example 1-2. In many examples of Examples 1 to 3, when C+Ex (the total unit amount of Portland cement and expansive additive) is about 20 kg / m 3 More than 130kg / m 3 Less than or equal to 87 kg / m 3 More than 130kg / m 3 The results are as follows. Example 4 is thought to show a similar trend to other examples with a high mass ratio of C+Ex (for example, Examples 2-3 to 2-6). Example 5 has a high mass ratio of C+Ex, so it is expected that the temperature rise will be intermediate between the other examples and the comparative examples. Examples 4 and 5 exhibit significantly higher compressive strength than the comparative examples (Figure 1), so it is thought that they have achieved both suppression of temperature rise and high compressive strength.

[0023] From the above, in order to ensure a certain compressive strength while reducing drying shrinkage and heat generation in a concrete composition containing binder, fine aggregate, coarse aggregate, chemical admixtures, and water, it is preferable to use slag fine aggregate with a water absorption of 1.5% or more as the fine aggregate and to include Portland cement, silica fume, and an expansive additive as the binder. However, in cases where a slight decrease in compressive strength is acceptable, as in Example 2-7, cement is not essential, and the binder must contain at least silica fume and an expansive additive.

[0024] The total mass ratio of Portland cement and expansive additive (C+Ex) in the binder is preferably 20% or more and 85% or less (Examples 1 to 5), more preferably 20% or more and 55% or less (Examples 1 to 4), and even more preferably 20% or more and 30% or less (Examples 1 to 2, 3-1 to 3-4).

[0025] The mass ratio of silica fume in the binder is preferably 10% or more and 15% or less, and since a variation of about 10% is thought not to have a significant effect on compressive strength, drying shrinkage strain, or temperature rise, a preferable range can be 9% or more and 17% or less. The binder contains fly ash, and the mass ratio of fly ash in the binder is preferably 20% or more and 30% or less (18% or more and 33% or less, including a 10% variation). The binder contains blast furnace slag, and the mass ratio of blast furnace slag in the binder is preferably 15% or more and 51% or less. The unit amount of water is 100 kg / m 3 More than 140kg / m 3 Preferably less than 120 kg / m 3 More than 140kg / m 3 The water-binder ratio is preferably 20% or more and 40% or less, and more preferably 25% or more and 35% or less.

[0026] In particular, Example 1 is preferable in that it can suppress both drying shrinkage and heat generation. Specifically, the binder contains Portland cement, an expansive agent, silica fume, fly ash, and blast furnace slag. -The total mass ratio of Portland cement and expansive additive in the binder is approximately 25% (22% to 28%, with a 10% variation). -The mass ratio of silica fume in the binder is approximately 15% (13% to 17%, including a 10% variation). -The mass ratio of fly ash in the binder is approximately 30% (27% to 33%, with a 10% variation). -The mass ratio of blast furnace slag in the binder is approximately 30% (27% to 33%, including a 10% variation). -However, the total mass ratio of Portland cement, expansive material, silica fume, fly ash, and blast furnace slag is 100%. The unit amount of water is preferably about 130 kg / m 3 (130kg / m including 10% variation) 3 More than 143kg / m 3 Preferably, the water-to-binder ratio is about 30% (27% to 33%, with a 10% variation).

[0027] The present invention has been described above using examples, but the present invention is not limited to these examples. The slag fine aggregate is air-crushed ferronickel slag fine aggregate. The slag fine aggregate in the examples is air-crushed ferronickel slag fine aggregate, but is not limited to this as long as it has a water absorption rate of 1.5% or more. The examples are concrete compositions containing coarse aggregate, but mortar compositions not containing coarse aggregate may also be used.

Claims

1. The concrete comprises a binder, slag fine aggregate having a water absorption rate of 1.5% or more, and water; the binder contains an expansive material and at least one selected from the group consisting of portland cement, blast furnace slag, fly ash, and silica fume; Unit water volume is 100 kg / m 3 More than 140kg / m 3 Hereinafter, a composition containing a binder, aggregate, and water, wherein the water-binder ratio is 20% or more and 40% or less.

2. The composition according to claim 1, wherein the binder contains the Portland cement, and the sum of the mass ratios of the Portland cement and the expansive material in the binder is 20% or more and 85% or less.

3. The composition according to claim 2, wherein the total mass ratio of the Portland cement and the expansive material in the binder is 20% or more and 30% or less.

4. The composition according to claim 3 , wherein the binder contains the silica fume, and the mass ratio of the silica fume in the binder is 9% or more and 17% or less.

5. The composition according to claim 4 , wherein the binder contains the fly ash, and the mass ratio of the fly ash in the binder is 18% or more and 33% or less.

6. The composition according to claim 5, wherein the binder contains the blast furnace slag, and the mass ratio of the blast furnace slag in the binder is 15% or more and 51% or less.

7. the binder includes the Portland cement, the fly ash, and the blast furnace slag; The total mass ratio of the Portland cement and the expansive material in the binder is 22% or more and 28% or less, The mass ratio of the silica fume in the binder is 13% or more and 17% or less, The mass ratio of the fly ash in the binder is 27% or more and 33% or less, The composition according to claim 1, wherein the mass ratio of the blast furnace slag in the binder is 27% or more and 33% or less.

8. The binder contains the Portland cement, and the sum of the unit amounts of the Portland cement and the expansive agent is 87 kg / m 3 More than 130kg / m 3 2. The composition of claim 1, wherein:

9. The unit amount of water is 120 kg / m 3 More than 140kg / m 3 9. The composition of any one of claims 1 to 8, wherein:

10. 9. The composition of claim 1, wherein the slag fine aggregate is air-ground ferronickel slag fine aggregate.

11. The composition of any one of claims 1 to 8, comprising coarse aggregate.

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