Concrete composition and concrete member
A concrete composition using coal gasification slag fine aggregate with blast furnace slag fine powder and slaked lime addresses bleeding and alkali-silica reaction, enhancing the performance and durability of concrete.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-09-05
- Publication Date
- 2026-03-17
AI Technical Summary
Coal gasification slag fine aggregate exhibits lower water retention leading to bleeding and is prone to alkali-silica reaction due to high alkali metal oxide content, limiting its effective use in concrete.
A concrete composition combining coal gasification slag fine aggregate with blast furnace slag fine powder and slaked lime as a binder, optionally with an expansive agent, to suppress bleeding and alkali-silica reaction, while addressing high viscosity and freeze-thaw susceptibility.
The composition effectively suppresses bleeding and alkali-silica reaction, reduces viscosity, and mitigates freeze-thaw degradation, enabling the effective utilization of coal gasification slag in concrete.
Smart Images
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Abstract
Description
[Technical Field]
[0001] This invention relates to a concrete composition containing coal gasification slag fine aggregate, and to a concrete member. [Background technology]
[0002] Integrated coal gasification combined cycle (IGCC) is a power generation method that uses gasified coal as fuel. It is attracting attention as an environmentally friendly power generation technology because it has high power generation efficiency and can reduce CO2 emissions per unit of electricity generated. Furthermore, since coal gasification slag is produced as a by-product in combined cycle coal gasification power generation, research is underway to explore the uses of this coal gasification slag. For example, Non-Patent Document 1 proposes using coal gasification slag as fine aggregate in concrete. [Prior art documents] [Non-patent literature]
[0003] [Non-Patent Document 1] Concrete Library No. 163, "Design and Construction Guidelines for Concrete Using Coal Gasification Slag Fine Aggregate," Japan Society of Civil Engineers [Overview of the project] [Problems that the invention aims to solve]
[0004] The inventors of this invention conducted a detailed study on concrete members using fine aggregate made from coal gasification slag (hereinafter referred to as "coal gasification slag fine aggregate" as appropriate) and confirmed the following problems. Coal gasification slag fine aggregate has lower water retention compared to general fine aggregate. Therefore, concrete members using coal gasification slag fine aggregate tend to exhibit more bleeding. Furthermore, coal gasification slag fine aggregate contains relatively high amounts of alkali metal oxides (such as NaO2 and K2O). Therefore, concrete members using coal gasification slag fine aggregate are highly likely to undergo alkali-silica reaction (ASR), one of the deterioration phenomena. Therefore, the inventors considered that if a technology could be created that could suppress bleeding and alkali-silica reaction in concrete members, even when using coal gasification slag fine aggregate, it would be possible to secure effective uses for coal gasification slag.
[0005] Therefore, the object of the present invention is to provide a concrete composition and concrete member that contain coal gasification slag fine aggregate while suppressing bleeding and alkali-silica reaction. [Means for solving the problem]
[0006] The inventors of this invention conducted research on materials for concrete compositions and found that when using coal gasification slag fine aggregate, the occurrence of bleeding and alkali-silica reaction can be suppressed by using a binder for so-called environmentally friendly concrete compositions (a binder containing blast furnace slag fine powder), leading to the creation of this invention. Furthermore, while environmentally friendly concrete compositions tend to have high viscosity due to the large amount of powder used and are prone to freeze-thaw reactions, the inventors have found that these problems can be resolved by using fine aggregate made from coal gasified slag. In other words, the inventors have found that by combining two components, "containing coal gasification slag fine aggregate as fine aggregate" and "containing blast furnace slag fine powder as a binder," the aforementioned problems caused by coal gasification slag fine aggregate (bleeding, alkali-silica reaction) can be solved, while simultaneously resolving problems specific to environmentally friendly concrete compositions (high viscosity, susceptibility to freeze-thaw reactions).
[0007] The aforementioned problem can be solved by the following means. The concrete composition according to the present invention is a concrete composition containing a binder, fine aggregate, coarse aggregate, and water, wherein the fine aggregate includes coal gasification slag fine aggregate, and the binder includes blast furnace slag fine powder and slaked lime. According to the present invention, since the fine aggregate contains coal gasification slag fine aggregate and the binder contains blast furnace slag fine powder, bleeding and alkali-silica reaction can be suppressed. In addition, according to the present invention, the specific problems that occur when using a binder containing blast furnace slag fine powder (high viscosity, susceptibility to freeze-thaw reaction) can also be resolved. The concrete composition according to the present invention has a blast furnace slag fine powder content of 250 kg / m³. 3 The above is preferable. Furthermore, the concrete composition according to the present invention preferably contains an expansive agent as the binder. Furthermore, the concrete composition according to the present invention preferably contains 30 parts by mass or more of coal gasification slag fine aggregate when the fine aggregate is 100 parts by mass. Note that a hydraulic composition that does not contain Portland cement in the binder may also be included in the concrete composition according to the present invention. According to the present invention, bleeding and alkali-silica reactions can be more reliably suppressed. The concrete member according to the present invention is made of the concrete composition described above. According to the present invention, since the concrete member is made of the aforementioned concrete composition, bleeding and alkali-silica reaction can be suppressed, and the specific problems that occur when using a binder containing blast furnace slag fine powder (high viscosity, susceptibility to freeze-thaw reaction) can also be resolved. [Effects of the Invention]
[0008] The concrete composition and concrete member according to the present invention contain coal gasification slag fine aggregate while suppressing bleeding and alkali-silica reaction. [Brief explanation of the drawing]
[0009] [Figure 1]It is a graph showing the results of the breeding test. [Figure 2] It is a graph showing the results of the ASR test. [Figure 3] It is a graph showing the results of the freeze-thaw test.
Mode for Carrying Out the Invention
[0010] Hereinafter, embodiments (embodiments) for implementing the concrete composition and the concrete member according to the present invention will be described. [Concrete Composition] The concrete composition according to the present embodiment is a hydraulic composition containing a binder, fine aggregate, coarse aggregate, and water. The fine aggregate includes coal gasification slag fine aggregate, and the binder includes blast furnace slag fine powder and slaked lime. Hereinafter, each constituent element constituting the concrete composition according to the present embodiment will be described in detail.
[0011] (Binder) The binder is a material that reacts with water and contributes to the development of strength, includes blast furnace slag fine powder and slaked lime, and preferably further includes an expansion agent. The present inventors have found that by containing blast furnace slag fine powder as a binder, problems (bleeding, alkali-silica reaction) caused by the coal gasification slag fine aggregate described later can be solved. The blast furnace slag fine powder is obtained by drying and pulverizing blast furnace water-quenched slag or adding gypsum thereto, and is defined in JIS A6206:2013. The slaked lime is calcium hydroxide (Ca(OH)2). The expansion agent is a admixture having an action of expanding concrete or mortar, and is defined in JIS A6202:2017. The expansion agent is preferably, for example, a lime-based expansion agent that elutes calcium ions, a calcium sulfoaluminate-based expansion agent, or the like.
[0012] The content of blast furnace slag fine powder in the concrete composition is 250 kg / m3 The above is preferable, and 255 kg / m 3 More than 260kg / m 3 More than 265kg / m 3 The above is more preferable. By having a blast furnace slag fine powder content above a predetermined value, bleeding and alkali-silica reactions can be more reliably suppressed. While there is no particular upper limit to the content of blast furnace slag fine powder in the concrete composition, for example, 600 kg / m³ 3 Below 550kg / m 3 The following applies:
[0013] The binder may consist of a combination of blast furnace slag powder and slaked lime, or a combination of blast furnace slag powder, slaked lime, and an expansive agent. In addition, it may also contain various types of cement (as specified in JIS R5210:2009), stimulants other than slaked lime (such as quicklime and Portland cement), limestone powder, fly ash, and light calcium carbonate. Alternatively, blast furnace cement as specified in JIS R5211:2019, which is mixed with blast furnace slag, may be used as a binder.
[0014] (Fine aggregate) Fine aggregate refers to aggregate that passes through a 10 mm mesh sieve completely and passes through a 5 mm mesh sieve by mass of 85% or more, and in this invention, it includes coal gasification slag fine aggregate. The inventors have found that by including coal gasification slag fine aggregate as fine aggregate, it is possible not only to secure the use of lime gasification slag, but also to resolve problems such as "high viscosity" and "ease of freeze-thaw reaction" that are characteristic of concrete compositions containing blast furnace slag fine powder as a binder (so-called environmentally friendly concrete compositions). Furthermore, the coal gasification slag fine aggregate conforms to JIS A5011-5:2020 and is made by granulating molten slag, a by-product of gasifying coal in a gasifier, with water and adjusting the particle size through grinding or other methods.
[0015] When the fine aggregate is 100 parts by mass, the content of the coal gasification slag fine aggregate is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, and still more preferably 50 parts by mass or more. By having the content of the coal gasification slag fine aggregate be a predetermined value or more, the effects of reducing viscosity and suppressing the occurrence of freeze-thaw action can be more reliably exhibited. Also, for the same reason, the content of the fine aggregate in the concrete composition is preferably 230 kg / m 3 or more, more preferably 300 kg / m 3 or more, and still more preferably 400 kg / m 3 or more. Note that when the fine aggregate is 100 parts by mass, although the upper limit of the content of the coal gasification slag fine aggregate is not particularly limited, for example, it is 100 parts by mass or less, 80 parts by mass or less. Also, although the upper limit of the content of the coal gasification slag fine aggregate in the concrete composition is not particularly limited, for example, it is 900 kg / m 3 or less, 850 kg / m 3 or less.
[0016] Note that as the fine aggregate, in addition to the coal gasification slag fine aggregate, fine aggregates conforming to Appendix A of JIS A5308, for example, crushed stone and crushed sand, slag aggregate, artificial lightweight aggregate, recycled aggregate, and gravel and sand may be included.
[0017] (Coarse aggregate) Coarse aggregate is aggregate that remains at 85% or more by mass on a 5 mm sieve, and conforms to Appendix A of JIS A5308. Although the content of the coarse aggregate in the concrete composition is not particularly limited, for example, it is 700 kg / m 3 or more, 900 kg / m 3 or more, 1000 kg / m 3 or more, and is 1300 kg / m 3 or less, 1100 kg / m 3 or less.
[0018] (Water) Water is not particularly limited, and tap water, groundwater, sludge water, etc. can be used. Water-powder ratio (= water content (kg / m 3 ) / Powder content (kg / m³ 3 The values of () × 100) are not particularly limited, but for example, they could be 20.0% or more, 25.0% or more, 60.0% or less, and 55.0% or less.
[0019] (Other materials) The concrete member according to this embodiment may appropriately contain conventionally known materials used in general concrete (e.g., chemical admixtures), to the extent that the desired effects of the present invention are not hindered. Examples of chemical admixtures include AE agents, high-performance water-reducing agents, curing accelerators, water-reducing agents, AE water-reducing agents, high-performance AE water-reducing agents, and fluidizing agents, as specified in JIS A6204:2011.
[0020] [Concrete members] The concrete member according to this embodiment is a member (hardened body after construction) made of the concrete composition described above. Furthermore, since the concrete member according to this embodiment is made of a concrete composition with the above-mentioned component composition, bleeding and alkali-silica reaction can be suppressed, viscosity can be reduced, and freeze-thaw effects can be suppressed.
[0021] [Method for manufacturing concrete composition, and method for manufacturing concrete member] The method for manufacturing a concrete composition according to this embodiment includes the step of preparing each of the materials described above. The method for manufacturing a concrete member according to this embodiment includes the steps of mixing, pouring, curing, etc., after the above steps. Furthermore, the processing in each step should be carried out under the same conditions as those used to manufacture general concrete compositions and concrete components. [Examples]
[0022] [material] Tables 1 and 2 show the formulations of each sample (concrete composition) used in the examples. Table 3 shows the details of each material used in each sample. Note that the percentages (%) of admixtures and air-enhancing agents in Tables 1 and 2 represent the proportion of the total powder amount.
[0023] [Table 1]
[0024] [Table 2]
[0025] [Table 3]
[0026] (Test content: Slump test) The slump test was conducted in accordance with JIS A1101:2020, "Method for Slump Testing of Concrete." The slump test was performed by adjusting the amounts of admixtures and air-entraining agents added so that the target slump was 18 ± 2.5 cm and the air content was 4.5 ± 1.5%. Tables 1 and 2 show the results of the slump test. In this slump test, it can be concluded that the lower the amount of admixture (and AE agent) added, the more the viscosity can be reduced. The samples subjected to the slump test were samples 1-1 to 1-8 and 2-1 to 2-5.
[0027] (Test content: Breeding test) The bleeding test was conducted in accordance with JIS A1123:2012, "Method for bleeding tests of concrete." Table 4 and Figure 1 show the results of the breeding test. In this breeding test, the smaller the breeding volume, the more effectively breeding was suppressed, and 0.1 cm 3 / cm 2 The following can be considered particularly favorable. The samples used in the breeding test were samples 1-1 to 1-8.
[0028] [Table 4]
[0029] (Test content: ASR test) The ASR test was conducted in accordance with JIS A1146:2017, "Test Method for Alkali-Silica Reactivity of Aggregates (Mortar Bar Method)". Table 5 and Figure 2 show the results of the ASR test. In this ASR test, the lower the expansion rate, the more effectively the alkali-silica reaction is suppressed. If the expansion rate exceeds 0.1% within the 50-week accelerated aging period, it is determined that the alkali-silica reaction is not suppressed and the material is reactive. The samples subjected to ASR testing were samples 1-1 to 1-8 (excluding sample 1-6).
[0030] [Table 5]
[0031] (Test content: Freeze-thaw test) The freeze-thaw test was conducted in accordance with JIS A1148:2010, "Test Method for Freeze-Thaw Testing of Concrete." Figure 3 shows the results of the freeze-thaw test. In this freeze-thaw test, the closer the relative dynamic modulus is to 100%, the more effectively the freeze-thaw process, which is a degradation phenomenon, can be suppressed. The samples that underwent freeze-thaw testing were samples 2-1 to 2-5.
[0032] [Review of results] (Results of the slump test) Table 1 shows the slump test results for samples 1-1 to 1-8, and Table 2 shows the slump test results for samples 2-1 to 2-5. From these results, the results for samples 1-1 to 1-4 confirmed that even when blast furnace slag fine powder is included, the amount of admixture (and AE agent) required to achieve the target slump decreases as the content of coal gasification slag fine aggregate increases. In other words, it was found that by including coal gasification slag fine aggregate in the concrete composition, the "viscosity" that is a problem when blast furnace slag fine powder is included can be reduced, or in other words, the fresh properties (mixability) can be improved.
[0033] (Results of the breeding test) Table 4 and Figure 1 show the results of the breeding tests for samples 1-1 to 1-8. Since samples 1-8 contained fine aggregate from coal gasification slag, the bleeding amount was 0.1 cm. 3 / cm 2 This significantly exceeded the previous level, confirming that breeding was clearly occurring. On the other hand, the results for samples 1-2 to 1-6 showed that even though they contained coal gasification slag fine aggregate, they also contained blast furnace slag fine powder, and therefore, unlike sample 1-8, the bleeding amount was 0.1 cm. 3 / cm 2 It was confirmed that bleeding could be suppressed without exceeding the limit. Also, since samples 1-7 also used blast furnace cement type B containing blast furnace slag as a binder, the amount of bleeding was 0.1 cm 3 / cm 2 Although it exceeded the limit, the breeding volume was less than that of samples 1-8. In other words, it was found that by incorporating blast furnace slag fine powder into the concrete composition, the occurrence of "bleeding," which is a problem when coal gasification slag fine aggregate is included, can be suppressed.
[0034] (Results of the ASR test) Table 5 and Figure 2 show the results of the ASR test for samples 1-1 to 1-8 (excluding sample 1-6). Since samples 1-8 contained fine aggregate from coal gasification slag, their expansion rate exceeded 0.1% during the ASR test period, confirming that alkali-silica reaction had clearly occurred. On the other hand, samples 1-2 to 1-5 and 1-7 not only contained coal gasification slag fine aggregate but also blast furnace slag fine powder (or used blast furnace cement type B). Unlike sample 1-8, their expansion rate did not exceed 0.1% during the ASR test period, confirming that the occurrence of alkali-silica reaction was suppressed. In other words, it was found that by including blast furnace slag fine powder in the concrete composition, the occurrence of the "alkali-silica reaction," which is a problem when coal gasification slag fine aggregate is included, can be suppressed.
[0035] (Results of freeze-thaw test) Figure 3 shows the results of the freeze-thaw test for samples 2-1 to 2-5. Since samples 2-1 and 2-2 contained blast furnace slag fine powder, it was confirmed that the relative dynamic elastic modulus decreased and that freeze-thaw action was clearly occurring. On the other hand, although samples 2-3 to 2-5 contained blast furnace slag fine powder, they also contained coal gasification slag fine aggregate. As a result, unlike samples 2-1 and 2-2, the relative dynamic elastic modulus did not decrease significantly, and it was confirmed that the occurrence of freeze-thaw action was suppressed. In other words, it was found that by including coal gasification slag fine aggregate in the concrete composition, the occurrence of "freeze-thaw action," which is a problem when blast furnace slag fine powder is included, can be suppressed.
[0036] (Summary of results) From the above results, it was confirmed that by including not only coal gasification slag fine aggregate as fine aggregate, but also blast furnace slag fine powder as a binder, it is possible to solve the problems caused by coal gasification slag fine aggregate (bleeding, alkali-silica reaction), and at the same time, the specific problems that occur when blast furnace slag fine powder is included (high viscosity, susceptibility to freeze-thaw reaction) can also be resolved.
Claims
1. A concrete composition containing a binder, fine aggregate, coarse aggregate, and water, The fine aggregate includes coal gasification slag fine aggregate. The aforementioned binder is a concrete composition characterized by containing blast furnace slag fine powder and slaked lime.
2. The content of the blast furnace slag fine powder is 250 kg / m³. ３ The concrete composition according to claim 1, characterized in that it is as described above.
3. The concrete composition according to claim 1 or 2, characterized in that the binder includes an expansive agent.
4. The concrete composition according to claim 1 or claim 2, wherein when the fine aggregate is 100 parts by mass, the coal gasification slag fine aggregate is 30 parts by mass or more.
5. A concrete member comprising the concrete composition according to claim 1 or claim 2.