Roadbed material and its manufacturing method

Abstract

To provide a roadbed material and a method for manufacturing the same that can reduce the burden on the environment and reduce carbon dioxide emissions. [Solution] The roadbed material (RB) of the present invention contains blast furnace slag fine powder (A: a hydraulic admixture produced by finely grinding blast furnace granulated slag, a by-product of blast furnaces in steel mills), an stimulant (B), and aggregate derived from construction by-products (C: RC material), and does not contain novel aggregate or novel cement. Furthermore, the method for laying the roadbed material at a construction site includes the steps of spreading aggregate at the construction site, mixing blast furnace slag fine powder and the stimulant, scattering the mixture of blast furnace slag fine powder and the stimulant onto the spread aggregate, and mixing the mixture of blast furnace slag fine powder and the stimulant with the aggregate, wherein the mixing step involves mixing the blast furnace slag fine powder and the stimulant with the aggregate only once, and includes the steps of spreading and compacting the mixture of blast furnace slag fine powder, stimulant, and aggregate.

Description

Technical Field

[0001] The present invention relates to a roadbed for paving, and more particularly to a stabilized roadbed formed using a material added with a stabilizing agent (or solidifying agent).

Background Art

[0002] All construction by-products, which are all items obtained incidentally during construction work, include, as their types, construction-generated soil carried out of the construction site, concrete blocks, asphalt-concrete blocks, construction-generated wood, construction sludge, paper scraps, metal scraps, glass scraps - concrete scraps (excluding those generated during the new construction, renovation, or removal of structures), and pottery scraps, or construction mixed waste in which these are mixed. As a conventional technique for effectively using such construction by-products, there is a technique of adding fly ash, which is ash generated when burning coal, sewage sludge incineration ash, gypsum, waste tires, oyster shells, etc. to construction by-products.

[0003] In recent years, reduction of carbon dioxide (CO2) emissions has become a major demand. As one of the countermeasures, it is conceivable to suppress emissions by mixing a substance having carbon dioxide absorption ability (carbon dioxide absorbent) into a paved roadbed and absorbing carbon dioxide in the paved roadbed. Here, it is known that when a carbon dioxide absorbent absorbs carbon dioxide to the limit, it loses the ability to absorb carbon dioxide any further. And it is also known that there are carbon dioxide absorbents that repeat absorption and release by applying some external force such as heat or pressure to the absorbed carbon dioxide. The applicant of the present application has provided a roadbed material having carbon dioxide absorption ability and the ability to recover it (see Patent Document 1). A road having a roadbed constituted by such a roadbed material can absorb more carbon dioxide and reduce carbon dioxide in the atmosphere.

[0004] Although such a roadbed material (the roadbed material of Patent Document 1) is a useful technique, there is a demand to further reduce the environmental load and further reduce the carbon dioxide emissions. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2024-3311 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] This invention was proposed in view of the above-mentioned requirements, and aims to provide a roadbed material and a method for manufacturing the same that can reduce the burden on the environment and reduce carbon dioxide emissions. [Means for solving the problem]

[0007] The roadbed material (RB) of the present invention is characterized by containing blast furnace slag fine powder (A: a hydraulic admixture produced by finely grinding blast furnace granulated slag, a by-product of blast furnaces in steel mills: fly ash), a stimulant (B), and aggregate derived from construction by-products (C: RC material), and not containing novel aggregates or novel cement. Here, "new" means that it has never been used as a construction material for buildings, roads, etc. In the present invention, it is preferable that the blast furnace slag fine powder is 1 to 30% by weight relative to the aggregate, and the stimulant is 1 to 10% by weight relative to the aggregate.

[0008] In a method for laying the aforementioned roadbed material (RB: roadbed material according to claim 1) at a construction site (CS, the road on which the roadbed material RB is to be installed), The process of spreading aggregate (C) derived from construction by-products at the aforementioned construction site (CS), The process involves mixing blast furnace slag fine powder (A: a hydraulic admixture produced by finely grinding blast furnace granulated slag, a by-product of blast furnaces in steel mills: fly ash) and an irritant (B), A step of scattering a mixture of blast furnace slag fine powder (A) and an irritant (B) onto the laid aggregate (C), The process includes introducing a stabilizer (10) or construction machinery to the construction site (CS) and mixing a mixture of blast furnace slag fine powder (A) and stimulant (B) with the aggregate (C), In the aforementioned mixing process, once the blast furnace slag fine powder (A) and irritant (B) are mixed uniformly with aggregate derived from construction by-products (C: RC material), no further mixing is performed. The method is characterized by including a step of spreading and compacting a mixture of blast furnace slag fine powder (A), an irritant (B), and the aggregate (C).

[0009] Furthermore, in a method for laying the roadbed material (RB: roadbed material according to claim 1) at a construction site (CS: road where roadbed material A is to be installed), The aforementioned construction site (CS) is in a state where a stabilizer (10) or construction machinery cannot be installed. A step of spreading aggregate (C) derived from construction by-products in an area (AS) that is different from the aforementioned construction site (CS) and in which a stabilizer (10) or construction machinery can enter, The process involves mixing blast furnace slag fine powder (A: a hydraulic admixture produced by finely grinding blast furnace granulated slag, a by-product of blast furnaces in steel mills: fly ash) and an irritant (B), A step of scattering a mixture of blast furnace slag fine powder (A) and an irritant (B) onto the laid aggregate (C), The process includes introducing a stabilizer (10) or construction machinery into the aforementioned region (AS) to mix a mixture of blast furnace slag fine powder (A) and stimulant (B) with the aggregate (C), In the aforementioned mixing process, blast furnace slag fine powder (A) and stimulant (B) are mixed once with aggregate derived from construction by-products (C: RC material), and no further mixing is performed. The process involves loading the mixture mixed by a stabilizer (10) or construction machinery onto a transport means (12: for example, a dump truck) as roadbed material (RB) and transporting it to the construction site (CS), The method is characterized by including a step of spreading and compacting the aforementioned roadbed material (RB) at the construction site (CS). Here, simple stirring, such as scooping with a bucket, does not constitute "mixing" as defined herein. In other words, "simple stirring, such as scooping with a bucket," is not included in the aforementioned "mixing."

[0010] Furthermore, in a method for manufacturing the roadbed material (RB: roadbed material according to claim 1), The process includes an input step in which blast furnace slag fine powder (A), an irritant (B), aggregate derived from construction by-products (C: RC material), and water are put into a mixing device (21: mixer), wherein no new aggregate or new cement is put into the mixing device (21) during the input step. The present invention is characterized by having a step of mixing in the aforementioned mixing device (21). [Effects of the Invention]

[0011] In conventional technology, it has been proposed to replace a portion of the aggregate and sand in the roadbed material with construction by-products, and a portion of the solidifying agent with blast furnace slag powder. According to this conventional technology, a portion of the cement, which generates a large amount of carbon dioxide during its manufacture, is replaced with blast furnace slag powder, and a portion of the aggregate and sand are replaced with construction by-products, thereby reliably reducing carbon dioxide emissions during the manufacture of roadbed material. Here, if all aggregates and sand are used as construction by-products, and all cement used as a solidifying agent is replaced with blast furnace slag powder, the carbon dioxide emissions during the production of roadbed material will be minimized. However, if all aggregates and sand were replaced with construction by-products, and all cement were replaced with blast furnace slag powder, there was a risk that the necessary strength for the roadbed material could not be obtained. Therefore, conventionally, the replacement of aggregates and sand with construction by-products was limited to a portion of the aggregates and sand, and the replacement of cement with blast furnace slag powder was also limited to a portion of the cement. Through various studies, the inventor discovered that even if all aggregates and sand were replaced with construction by-products, and all cement was replaced with blast furnace slag powder, the strength of the roadbed material would not decrease.

[0012] The roadbed material (RB) of the present invention having the above-described configuration has been proposed based on such findings. According to the inventor's experiments, it contains blast furnace slag fine powder (A), activator (B), and aggregate (C: RC material) derived from construction by-products, does not include novel aggregate and novel cement, but can exhibit a uniaxial compressive strength of 2.9 MPa or more required as an upper-layer roadbed material. And since the roadbed material (RB) of the present invention does not include novel cement, it does not emit a large amount of carbon dioxide during manufacturing. Further, since RC material is used as the aggregate (C), the amount of carbon dioxide emissions can be reduced compared to novel aggregate.

[0013] The inventor also found that in a roadbed material (RB) containing blast furnace slag fine powder (A), activator (B), and aggregate (C: RC material) derived from construction by-products, and not including novel aggregate and novel cement, when the blast furnace slag fine powder (A) and the activator (B) are mixed with the aggregate (C: RC material) derived from construction by-products only once and no further mixing is performed thereafter, the strength (uniaxial compressive strength) of the roadbed material (RB) composed of the mixture is improved. The method for laying the roadbed material of the present invention has been proposed based on such findings. When introducing a stabilizer (10) or construction machinery to mix the mixture of blast furnace slag fine powder (A) and activator (B) with the aggregate (C), once mixing is performed, no further mixing is performed thereafter. Therefore, according to the laying method of the present invention, the strength of the roadbed material (RB) containing blast furnace slag fine powder (A), activator (B), and aggregate (C: RC material) derived from construction by-products, and not including novel aggregate and novel cement, is improved.

Brief Description of the Drawings

[0014] [Figure 1] It is a cross-sectional view showing an example of a road using the roadbed material according to an embodiment of the present invention. [Figure 2] It is a characteristic diagram showing the experimental results of measuring the uniaxial compressive strength of the roadbed material by changing the amount of blast furnace slag fine powder in the mixing example shown in Table 2. [Figure 3] It is a characteristic diagram showing the results of the ramming test of the roadbed material according to the embodiment. [Figure 4] This figure shows the results of a soil elution survey, which evaluates the environmental safety of the roadbed material according to the embodiment, in table format. [Figure 5] This figure shows the estimated CO2 emissions for the roadbed material with the composition shown in Table 2. [Figure 6] This is an explanatory diagram illustrating the general process of manufacturing roadbed material by mixing it at the construction site. [Figure 7] This flowchart shows the procedure for manufacturing roadbed material by mixing it at the construction site. [Figure 8] This is an explanatory diagram illustrating the general process of manufacturing roadbed material using construction machinery and other equipment at locations other than the construction site. [Figure 9] This flowchart shows the procedure for manufacturing roadbed material using construction machinery and other equipment at a location other than the construction site. [Figure 10] This is an explanatory diagram illustrating the general process of manufacturing roadbed materials at a plant rather than on the construction site. [Figure 11] This flowchart shows the procedure for manufacturing roadbed material at the plant. [Figure 12] Figures 6 to 9 show experimental results comparing the strength of two-step mixing versus one-step mixing in the cases shown. [Modes for carrying out the invention]

[0015] Embodiments of the present invention will be described below with reference to the attached drawings. First, a roadbed material according to an embodiment of the present invention will be described. An example of a road R using the roadbed material RB according to the embodiment is shown in Figure 1. The surface layer R1 of the road R shown in Figure 1 is paved with an asphalt mixture, and the subbase material RB according to the illustrated embodiment is laid as the upper subbase R2. For the lower subbase R3, a granular subbase containing, for example, C40 crushed stone (crusher run) is used. The lower layer R4 of the lower subbase is the roadbed. Here, the quality standards for roads stipulate that the uniaxial compressive strength (7 days old) of the upper subbase R2 must be 2.9 MPa or higher, and the uniaxial compressive strength (7 days old) of the lower subbase R3 must be 0.98 MPa or higher (Japan Road Association "Pavement Recycling Handbook"). As will be described later, experiments conducted by the inventor showed that the roadbed material RB according to the illustrated embodiment had a uniaxial compressive strength of 2.9 MPa or more at 7 days of age, and possessed strength exceeding the road quality standards.

[0016] The roadbed material RB according to this embodiment contains blast furnace slag fine powder A, which is a solidifying agent, an agitator B, and recycled concrete aggregate C (RC material), which is an aggregate corresponding to gravel, crushed stone, etc. Its composition is as shown in Table 1 below. Table 1 TIFF2026067034000002.tif23122

[0017] In the roadbed material RB according to this embodiment, no new materials (materials not previously used) are used for the solidifying agent, blast furnace slag fine powder A, and aggregate C. Blast furnace slag powder (fly ash), a hydraulic admixture produced by finely grinding blast furnace granulated slag, a by-product of blast furnaces in steel mills, does not qualify as a new material. Furthermore, recycled concrete aggregate (RC material), used as aggregate, is made from recycled concrete and aggregate (aggregates derived from construction by-products) that have been used at least once in some kind of structure (including roads), and therefore does not qualify as a new material. Both blast furnace slag fine powder A and recycled concrete aggregate C can be obtained without emitting large amounts of carbon dioxide during their manufacturing process. Therefore, the roadbed material RB according to this embodiment does not release a large amount of carbon dioxide during manufacturing, and the overall amount of carbon dioxide emitted can be reduced compared to conventional technology.

[0018] As a solidifying agent other than blast furnace slag fine powder, for example, fly ash can be used. Stimulant B is necessary to promote the latent hydraulic properties of blast furnace slag powder A. Alkaline by-products (for example, by-products from the production of limestone or slaked lime) can be used as the stimulant. Existing commercially available stimulants can be used (for example, "By-product Lime" from Maruo Calcium Co., Ltd. as slaked lime (by-product material), "Cake D" from Chichibu Lime Industry Co., Ltd. as concrete sludge, "Dolomistic Lime 50", "Dolomistic Lime 70", and "Dolomistic Lime 100" from Yoshizawa Lime Industry Co., Ltd. as dolomite-containing quicklime, and "Y Mix" from Yoshizawa Lime Industry Co., Ltd. as dolomite-containing limestone fine powder).

[0019] According to experiments conducted by the inventor, as described later, when the amount of blast furnace slag fine powder A was less than 1% by weight relative to the RC material C, the manufactured roadbed material RB could not achieve a uniaxial compressive strength of 2.9 MPa or higher, even when high-quality RC material was used. Furthermore, it was found that when the amount of stimulant B was less than 1% by weight relative to the aggregate C (RC material), it could not fulfill its role as a stimulant to accelerate the hardening of the solidification material. On the other hand, if the amount of blast furnace slag fine powder A exceeds 30% by weight relative to aggregate C (RC material), the amount of solidifying agent in powder form is too high, resulting in the manufactured roadbed material RB becoming loose and swollen (a so-called "squishy" state), and significantly reducing workability. Similarly, if the amount of stimulant B exceeds 10% by weight relative to aggregate C (RC material), workability and other properties also significantly decrease. Furthermore, the drying shrinkage effect after hardening increases, increasing the risk of crack formation.

[0020] Table 2 below shows examples of the composition of the roadbed material RB according to the illustrated embodiment. Table 2 TIFF2026067034000003.tif35115

[0021] Figure 2 shows the experimental results of measuring the uniaxial compressive strength (MPa) when the amount of blast furnace slag fine powder A (weight %) relative to the RC material was changed in the example formulations shown in Table 2. In Figure 2, it was found that for the roadbed material RB (100% recycled stabilized material that does not include new aggregates or new cement) in the example mix shown in Table 2, if the amount of blast furnace slag fine powder A, which is the solidifying agent for aggregate C (RC material), is 5.6% by weight or more, the upper roadbed material R2 (Figure 1) will exhibit the required unconfined compressive strength of 2.9 MPa or more (target value). The unconfined compressive strength (MPa) also changes in a roughly linear manner depending on the amount (%) of blast furnace slag fine powder A added to aggregate C (RC material), and if the amount added falls below 5.6% by weight, the required unconfined compressive strength of 2.9 MPa or more is not met. Note that the amount of stimulant B added does not have much effect on the unconfined compressive strength of the roadbed material RB. Furthermore, by adjusting the amount of blast furnace slag fine powder A, which is a solidifying agent, it was found that the roadbed material RB according to the illustrated embodiment can be used as the upper roadbed material R2 (Figure 1). Similarly, in the illustrated embodiment, by adjusting the amount of blast furnace slag fine powder A, which is a solidifying agent, the roadbed material RB according to the illustrated embodiment can also be used as a lower roadbed material R3 (required unconfined compressive strength of 0.98 MPa or higher). Here, as will be described later in the manufacturing and laying methods of the roadbed material RB shown in Figures 6 to 9, the inventor's experiments showed that when manufacturing roadbed material RB by mixing a mixture of blast furnace slag fine powder A and stimulant B with aggregate C (RC material), the unconfined compressive strength when the mixture of blast furnace slag fine powder A and stimulant B is mixed first and then mixed with aggregate C is stronger than the unconfined compressive strength when either blast furnace slag fine powder A or stimulant B is mixed with aggregate C, and the other, which is not mixed with aggregate C, is scattered and mixed into the mixture. In other words, the experiment revealed that when comparing the case where blast furnace slag fine powder A and / or stimulant B and aggregate C are mixed once with the case where they are mixed twice, the uniaxial compressive strength of the roadbed material is stronger when the mixture is mixed once.

[0022] Figure 2 also shows data for conventional cement-stabilized roadbed material. The conventional cement-stabilized roadbed material in Figure 2 is a roadbed material in which some of the aggregate and sand are replaced with construction by-products, and some of the solidifying agent is replaced with blast furnace slag powder. Even in the case of conventional cement-stabilized roadbed materials, the unconfined compressive strength (MPa) changes approximately linearly depending on the amount (by weight) of blast furnace slag fine powder added to aggregate C, making it possible to satisfy the unconfined compressive strength of 2.9 MPa or more (target value) required for roadbed materials. However, as mentioned above, in conventional cement-stabilized roadbed materials, the replacement of aggregate and sand with construction by-products is limited to a portion of the aggregate and sand, and the replacement with blast furnace slag fine powder is also limited to a portion of the cement. Therefore, compared to the roadbed material according to the embodiment, carbon dioxide emissions are higher.

[0023] From the experimental example shown in Figure 2, it was found that in the roadbed material according to the embodiment, even when the amount of blast furnace slag fine powder A is 1% by weight or more relative to the aggregate C (RC material), there are cases where the unconfined compressive strength is less than 2.9 MPa. The experimental example shown in Figure 2 concerns roadbed material RB of one mix example (Table 2), and the strength of roadbed material RB varies depending on the mix of constituent materials, the quality of the aggregate, and the quality of the solidifying agent. In other words, the amount of blast furnace slag fine powder A added to achieve the required unconfined compressive strength of 2.9 MPa for the upper roadbed material varies depending on the quality of the RC material. For example, in the case of a high-grade RC material such as recycled concrete aggregate H (JIS A5023) used as the roadbed material in the embodiment, if blast furnace slag fine powder A is added at a rate of 1% by weight or more relative to the RC material, the inventor has confirmed in another experiment that the unconfined compressive strength of the manufactured roadbed material RB at 7 days of age exceeds 2.9 MPa. On the other hand, in another experiment by the inventor, it has been confirmed that with lower-grade RC materials such as recycled concrete aggregate L (JIS A5023), even if the amount of blast furnace slag fine powder A added to the RC material is 5.6% by weight, the uniaxial compressive strength at 7 days may be less than 2.9 MPa. However, according to further experiments by the inventor, regardless of the grade of RC material, if the amount of blast furnace slag powder A added to the RC material was less than 1% by weight, the unconfined compressive strength of the manufactured roadbed material did not exceed 2.9 MPa. Furthermore, (regardless of the grade of RC material) if the amount of blast furnace slag powder A exceeded 30% by weight relative to the RC material, as described above, the manufactured roadbed material became loose and swollen (a so-called "squishy" state), and its workability was significantly reduced.

[0024] During the laying of roadbed material, the required strength is ensured by compacting the material through vibration and load. Even with the same compaction energy applied, the compaction density of roadbed material differs depending on its water content. Therefore, the relationship between the density and water content of the roadbed material is clearly defined and used in construction management. Figure 3 shows the compaction test results of the roadbed material according to the embodiment (100% recycled and stabilized roadbed material, with 5.6% by weight of blast furnace slag fine powder A and 2.0% by weight of stimulant B as examples of the composition). According to the characteristic curve of the compaction test results shown in Figure 3, in a roadbed material containing 5.6% by weight of blast furnace slag fine powder A and 2.0% by weight of stimulant B, the moisture content at which the dry density is maximum (optimal moisture content) is 14.8%, and the dry density at that time (maximum dry density) is 1.859 g / cm³. 3 That was the case. Figure 3 also shows the compaction test results for cement-stabilized roadbed material using conventional technology. The cement-stabilized roadbed material using conventional technology is a roadbed material in which some of the aggregate and sand are replaced with construction by-products, and some of the solidifying agent is replaced with blast furnace slag fine powder. According to the compaction curve of conventional cement-stabilized roadbed material, the optimal moisture content is 8.3%, and the maximum dry density at that point is 2.181 g / cm³. 3 That was the case.

[0025] Furthermore, the inventors conducted experiments on the constructability and durability of the roadbed material according to the embodiment. Experiments using a pavement durability evaluation test device (road simulator) were conducted to evaluate constructability and pavement durability. As a result, (1) 100% recycled stabilized roadbed material can be installed using the same method as general cement stabilized roadbed material, and there are no problems with workability. (2) As a result of driving tests using a road simulator, the road surface condition remained generally good even after 200,000 wheels were driven (based on a fatigue failure rate of 150,000 wheels / 10 years for planned N4 traffic on the pavement). (3) No decrease in bearing capacity was found in the pavement structure investigation using FWD (Falling Weight Deflectometer, a non-destructive testing device for investigating the soundness of pavement). The results of this experiment confirmed that 100% recycled stabilized roadbed material has the same workability and durability as conventional roadbed material.

[0026] The inventors investigated the soil elution levels of specific hazardous substances defined under the Soil Contamination Countermeasures Act regarding the environmental safety of the roadbed material according to the embodiment. The results are shown in the table in Figure 4. In the experiment in question, as shown in Figure 4, The following 12 specific hazardous substances are classified as Class I: chloroethylene, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene, 1,2-dichloroethylene, 1,3-dichloropropene, dichloromethane, tetrachloroethylene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethylene, and benzene. The nine specified hazardous substances of the second class are cadmium and its compounds, hexavalent chromium compounds, cyanide compounds, mercury and its compounds, selenium and its compounds, lead and its compounds, arsenic and its compounds, fluorine and its compounds, and boron and its compounds. The five specified hazardous substances of the third category are simazine, thiobengalb, thiraum, polychlorinated biphenyls, and organophosphorus compounds. The amount of each substance leached out was measured and compared with the standard values ​​for each substance. As shown in Figure 4, the soil leaching levels of all specified hazardous substances were lower than the standard values. Therefore, the risk of health damage due to the leaching of specified hazardous substances into groundwater, etc., is judged to be low.

[0027] Figure 5 shows the results of calculating the CO2 emissions during the manufacturing of the roadbed material RB according to the embodiment, with the composition shown in Table 2, and confirming the effect of reducing environmental load. In Figure 5, the "comparative material" is a conventional stabilized roadbed material, where the solidifying agent is cement and the aggregate is gravel. As shown in Figure 5, with conventional roadbed materials, the CO2 emissions during manufacturing are 45.2 kg-CO2 / m³ for the comparative material. 3 In contrast, the stabilized roadbed material RB according to the embodiment has a CO2 emission rate of 10.1 kg-CO2 / m³ during manufacturing. 3 As a result, CO2 emissions are reduced by more than 70% compared to conventional roadbed materials. Furthermore, since the amount of stimulant B added is extremely small compared to the solidifying agent, and its CO2 emission intensity is low, it is not shown in Figure 5.

[0028] Next, a method for manufacturing roadbed material according to an embodiment will be described with reference to Figures 6 to 11. Figures 6 and 7 illustrate a method for manufacturing roadbed material by mixing it at the construction site. Figure 6 shows an overview of the manufacturing of the roadbed material RB of the embodiment using the stabilizer 10 at the construction site CS (road). In Figure 6, in the right-hand region of the construction site CS, aggregate C (RC material) derived from construction by-products is laid and pre-compacted, and a mixture of blast furnace slag fine powder A and irritant B is scattered on the surface of aggregate C (RC material) facing the ground. The blast furnace slag fine powder A and irritant B are mixed in advance before being scattered on the surface of aggregate C (RC material) facing the ground. Blast furnace slag fine powder A is a hydraulic admixture produced by finely grinding blast furnace granulated slag, a by-product of blast furnaces in steel mills, and is a different type of material from fly ash. As the stimulant B, an alkaline by-product material (for example, a by-product of manufacturing limestone or slaked lime) is used. In the left-hand region of the construction site CS shown in Figure 6, the mixing mechanism 10A of the stabilizer 10 uniformly mixes the mixture of blast furnace slag fine powder A and stimulant B with aggregate C. In Figure 6, arrow A6 indicates the direction of travel of the stabilizer 10. After the mixture of blast furnace slag fine powder A and irritant B is mixed with aggregate C, it is compacted using a compaction machine (not shown).

[0029] Figure 7 shows the procedure for manufacturing the roadbed material RB by mixing it at the construction site CS. Although not explicitly shown in Figures 6 and 7, prior to laying the subgrade material RB on the road at the construction site CS (prior to step S1 in Figure 7), work is carried out to control the moisture content of the constituent material aggregate C (RC material) to an appropriate value (range). In step S1, aggregate C (RC material) is transported to the construction site CS. At the same time, blast furnace slag fine powder A and irritant B, which are constituent materials of the roadbed, are also brought to the construction site CS. Then the process proceeds to step S2. In step S2, aggregate C is spread and temporarily compacted on the road at the construction site CS (this is the process of spreading aggregate C derived from construction by-products on the construction site CS). Then, the process proceeds to step S3. In step S3, blast furnace slag fine powder A and irritant B are mixed (step of mixing blast furnace slag fine powder A and irritant B), and the mixed blast furnace slag fine powder A and irritant B mixture is spread onto the ground surface of the temporarily compacted aggregate C using a spreading machine (step of spreading the blast furnace slag fine powder A and irritant B mixture onto the leveled aggregate C). Instead of spreading, it is also possible to gather the blast furnace slag fine powder A and irritant B mixture into predetermined areas (for example, by putting it in bags) and place them there. Then proceed to step S4.

[0030] In step S4, the mixture of blast furnace slag fine powder A and irritant B, which has been scattered on aggregate C, is mixed with aggregate C (a mixing step in which the mixture of blast furnace slag fine powder A and irritant B is mixed with aggregate C). In the embodiments shown in Figures 6 and 7, a stabilizer 10 is introduced into the mixing operation, and the mixing operation in step S4 is performed. In step S5, following step S4, a compaction machine is used to spread and compact the mixture of blast furnace slag powder A, stimulant B, and aggregate C prepared in step S4 (spreading and compaction process). This completes the laying of the roadbed material RB.

[0031] Next, with reference to Figures 8 and 9, an outline of an embodiment in which roadbed material RB is manufactured using construction machinery at a location other than a construction site and not a plant will be described. In some cases, stabilizers 10 and other construction machinery (such as backhoes 11) as shown in Figures 6 and 7 may not be able to enter the construction site. In such cases, the roadbed material RB is manufactured according to the embodiments shown in Figures 8 and 9, and the manufactured roadbed material RB is transported to the construction site using a transport vehicle such as a dump truck 12. In Figure 8, aggregate C (RC material), blast furnace slag fine powder A, and irritant B, derived from construction by-products, are brought into an area other than the construction site that can be accessed by construction machinery such as a backhoe 11 (construction machinery access area AS). In the area AS accessible to construction machinery, aggregate C is laid and partially compacted, and a mixture of blast furnace slag fine powder A and irritant B is sprayed onto the surface of the partially compacted aggregate C (by a spraying machine not shown). The mixture of blast furnace slag fine powder A and irritant B is pre-mixed before being sprayed onto the aggregate C. Figure 8 shows the area on the left side of the area AS accessible to construction machinery with the mixture of blast furnace slag fine powder A and irritant B sprayed onto the surface of the aggregate C facing the ground.

[0032] Meanwhile, in the area to the right of the construction equipment access area AS shown in Figure 8, the backhoe 11 is shown mixing the aggregate C with a mixture of blast furnace slag fine powder A and stimulant B that has been scattered on the surface of the aggregate C. Arrow A8 indicates the direction of travel of the backhoe 11. The process of mixing aggregate C with a mixture of blast furnace slag fine powder A and stimulant B takes place in the construction equipment access area AS. After mixing, the mixture of aggregate C, blast furnace slag fine powder A, and stimulant B is shipped (transported) as roadbed material RB to the construction site CS (not shown in Figure 8). For the shipment (transportation) of roadbed material RB, the mixture of aggregate C, blast furnace slag fine powder A, and stimulant B is loaded onto a dump truck 12 by a backhoe 11 and transported to the construction site CS. Subsequently, at the construction site CS, the roadbed material RB, which is a mixture of aggregate C (RC material), blast furnace slag fine powder A, and irritant B, is laid and compacted. In Figure 8, the mixing of blast furnace slag aggregate C, fine powder A, and stimulant B was performed using a backhoe 11. However, this operation can also be performed using a stabilizer 10 or other construction machinery, as in the embodiments shown in Figures 6 and 7.

[0033] Referring to Figure 9, the procedure for manufacturing the roadbed material RB described in Figure 8 will be explained. Although not shown in Figures 8 and 9, when manufacturing the roadbed material RB in the construction machinery access area AS (a place other than the construction site) shown in Figure 8, prior to step S11 in Figure 9, the moisture content of the aggregate C (RC material) is controlled to an appropriate value (range). In step S11, aggregate C is brought into the area AS accessible to construction machinery (Figure 8). At the same time, the constituent materials, blast furnace slag fine powder A and irritant B, are also brought into the area AS accessible to construction machinery. Then the process proceeds to step S12. In step S12, aggregate C is spread and temporarily compacted in the area AS accessible to construction machinery (this is a process of spreading aggregate C derived from construction by-products in an area AS that is different from the construction site and accessible to construction machinery or stabilizers 10 and backhoes 11). Then the process proceeds to step S13. In step S13, the blast furnace slag fine powder A and irritant B are mixed (step of mixing blast furnace slag fine powder and irritant B), and the mixture of blast furnace slag fine powder A and irritant B is spread on the surface of aggregate C (by a spreading machine not shown) (step of spreading the mixture of blast furnace slag fine powder A and irritant B onto the leveled aggregate C). Instead of spreading, the mixture of blast furnace slag fine powder A and irritant B can also be bundled together in predetermined areas (for example, packed into bags) and placed. Then proceed to step S14.

[0034] In step S14, the mixture of blast furnace slag fine powder A and stimulant B, which was scattered on the aggregate C in step S13, is mixed with the aggregate C (a mixing step in which the mixture of blast furnace slag fine powder A and stimulant B is mixed with the aggregate C). In Figure 8, mixing is performed using a backhoe 11, but as shown in Figure 6, a stabilizer 10 can be used, and other machines can also be used. Then proceed to step S15. In step S15, the mixture of blast furnace slag fine powder A and stimulant B, and the mixture of aggregate C are loaded onto, for example, a dump truck 12 (transportation means) and transported to the construction site CS as stabilized roadbed material RB (transportation process). Then the process proceeds to step S16. In step S16, the roadbed material RB (a mixture of blast furnace slag fine powder A and irritant B and aggregate C) transported to the construction site CS is spread and compacted at the construction site CS (spreading and compaction process), and the roadbed material RB is laid.

[0035] As mentioned above, experiments conducted by the inventor showed that when the solidifying agent (blast furnace slag fine powder A) and the stimulant B were mixed and then sprinkled onto aggregate C (RC material), the strength (unconfined compressive strength) of the manufactured roadbed material RB improved compared to when the solidifying agent (blast furnace slag fine powder A) was sprinkled onto aggregate C (RC material) and mixed, and then the stimulant B was sprinkled and mixed afterward. Furthermore, the strength (unconfined compressive strength) of the roadbed material RB also improved compared to when the stimulant B was sprinkled onto aggregate C (RC material) and mixed, and then the solidifying agent A was sprinkled and mixed afterward. In other words, it was found that the strength of the manufactured roadbed material RB improved when the solidifying agent (blast furnace slag fine powder A) and / or stimulant B were mixed with aggregate C (RC material) once rather than twice. As explained with reference to Figures 6 to 9, when roadbed material is manufactured outside of a plant, the solidifying agent (blast furnace slag fine powder A) and stimulant B are mixed with aggregate C (RC material) only once. According to the inventor's experiments, in the cases shown in Figures 6 to 9, the uniaxial compressive strength of the manufactured roadbed material RB is stronger than when solidifying agent A or stimulant B is mixed with aggregate C twice (see Figure 12). In Figure 12, the vertical axis represents uniaxial compressive strength (N / mm²). 2 )

[0036] Referring to Figures 10 and 11, we will now explain the case in which roadbed material RB is manufactured at the plant. The plant 20 for manufacturing roadbed material shown in Figure 10 includes a mixer 21 (mixing device), RC material supply equipment 22 (aggregate supply equipment), blast furnace slag fine powder supply source 23 (solidifying material supply source), stimulant supply source 24, and water supply source 25. In the manufacturing plant 20, the RC material supply equipment 22 and the mixer 21 are connected by the RC material supply system 26, and the blast furnace slag fine powder supply source 23 and the mixer 21 are connected by the blast furnace slag supply system 27. In addition, the stimulant supply source 24 and the mixer 21 are connected by the stimulant supply system 28, and the water supply source 25 and the mixer 21 are connected by the water supply system 29. Furthermore, the manufacturing plant 20 has a roadbed material transport system 30 that transports the roadbed material RB (i.e., a mixture of aggregate C, blast furnace slag fine powder A, and irritant B) manufactured and discharged in the mixer 21 from the mixer 21 to the loading area. The roadbed material RB, transported via the roadbed material transport system 30, is loaded onto a dump truck 12 (transportation means) and transported to the construction site.

[0037] Figure 11 shows the procedure for manufacturing the roadbed material RB using the manufacturing plant 20 shown in Figure 10, and then laying the roadbed material RB at the construction site. In Figure 11, prior to the input of the constituent materials of the roadbed material RB (aggregate C, solidifying agent A, and stimulating agent B) into the mixer 21 (prior to step S21), the moisture content of aggregate C (RC material) is controlled to an appropriate value (range). This control work is carried out in the stockyard included in the RC material supply equipment 22. In step S21 of Figure 11, aggregate C, blast furnace slag fine powder A (solidifying agent), stimulant B, and water are added to the mixer 21. In step S21, aggregate C is transported from the RC material supply equipment 22 to the mixer 21 via the RC material supply system 26 and added; blast furnace slag fine powder A is transported from the blast furnace slag fine powder supply source 23 to the mixer 21 via the blast furnace slag supply system 27 and added; stimulant B is transported from the stimulant supply source 24 to the mixer 21 via the stimulant supply system 28 and added; and water is transported from the water supply source 25 to the mixer 21 via the water supply system 29 and added (this is the input process in which blast furnace slag fine powder A, stimulant B, aggregate C, and water are added to the mixer 21). Then the process proceeds to step S22. Although not explicitly shown in the diagram, when water is introduced (supplied) to the mixer 21, the amount of water supplied is controlled so that the water content is such that an optimal mixing state can be maintained within the mixer 21 during the mixing process in step S22. New aggregates and new cement will not be added to Mixer 21.

[0038] In step S22, the aggregate C, blast furnace slag powder A, stimulant B, and water introduced in step S21 are mixed in the mixer 21 to produce the stabilized roadbed material RB, which is a mixture (mixing process). Then the process proceeds to step S23. In step S23, the stabilized roadbed material RB manufactured in step S22 is transported via the roadbed material transport system 30 to the dump truck 12 (transportation means), and then transported to the construction site CS by the dump truck 12 (transportation process). Then the process proceeds to step S24. In step S24, the roadbed material RB (a mixture of blast furnace slag fine powder A, stimulant B, and aggregate C) transported to the construction site is spread and compacted at the construction site CS (spreading and compaction process), and the roadbed material RB is laid.

[0039] The illustrated embodiments are for illustrative purposes only and are not intended to limit the technical scope of the present invention. [Explanation of symbols]

[0040] 10. Stabilizer (construction machinery) 11. Backhoe 12. Dump truck (means of transport) 20. Manufacturing Plant 21. Mixer (mixing device) 22. RC material supply equipment (aggregate supply equipment) 23. Blast furnace slag fine powder supply source (solidifying agent supply source) 24... Source of stimulants 25...Water supply source 26...RC material supply system 27. Blast furnace slag supply system 28... Stimulant supply system 29...Water supply system 30... Roadbed material transport system A... Blast furnace slag fine powder B... Stimulant C...Aggregate (RC material) RB...roadbed material AS...Construction machine access area CS...Construction site

Claims

1. A roadbed material characterized by containing blast furnace slag fine powder, an irritant, and aggregate derived from construction by-products, but not containing novel aggregate or novel cement.

2. In a method for laying the roadbed material according to claim 1 at a construction site, The process of spreading aggregate derived from construction by-products at the aforementioned construction site, The process involves mixing blast furnace slag fine powder with an irritant, A step of scattering a mixture of blast furnace slag fine powder and an irritant onto the laid aggregate, The process includes introducing a stabilizer or construction machinery to the construction site and mixing a mixture of blast furnace slag fine powder and an irritant with the aggregate, In the aforementioned mixing process, once the blast furnace slag fine powder and irritant are mixed with aggregate derived from construction by-products, no further mixing is performed. A method for laying roadbed material, characterized by including the step of spreading and compacting a mixture of blast furnace slag fine powder, an agitator, and the aggregate.

3. In a method for laying the roadbed material according to claim 1 at a construction site, The aforementioned construction site is in a state where construction machinery or stabilizers cannot be introduced. A process of spreading aggregate derived from construction by-products in an area different from the aforementioned construction site, but in an area accessible by construction machinery or stabilizers, The process involves mixing blast furnace slag fine powder with an irritant, A step of scattering a mixture of blast furnace slag fine powder and an irritant onto the laid aggregate, The process includes introducing a stabilizer or construction machinery into the aforementioned region and mixing a mixture of blast furnace slag fine powder and an irritant with the aggregate, In the aforementioned mixing process, the blast furnace slag fine powder and irritant are mixed once with the aggregate (RC material) derived from construction by-products, and no further mixing is performed. The process involves loading the mixture, which has been mixed by a stabilizer or construction machinery, onto a transport means as roadbed material and transporting it to the construction site. A method for laying roadbed material, characterized by including the step of spreading and compacting the roadbed material at the construction site.

4. In a method for manufacturing roadbed material according to claim 1, The process includes an input step in which blast furnace slag fine powder, an irritant, aggregate derived from construction by-products, and water are put into a mixing device, and in the input step, new aggregate and new cement are not put into the mixing device. A method for manufacturing roadbed material, characterized by having a step of mixing with the aforementioned mixing device.

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