Construction of a site using water-hardened components and construction methods

Abstract

To provide a hydraulic composition which reduces the amount of materials to be procured from outside and enables paving of soft ground inexpensively and easily, and a paving method using the hydraulic composition. [Solution] A hydraulic composition containing a cementitious binder, fine aggregate, coarse aggregate, and water, wherein at least a portion of the coarse aggregate has an ID2 value of 90 or less as measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability), and the hydraulic composition has a flow value of 200 to 400 mm as measured in accordance with JHS A 313-1992 (Test Method for Air Mortar and Air Mortar).

Description

[Technical Field]

[0001] The present invention provides For ground paving The present invention relates to a hydraulic composition and a paving method using the hydraulic composition. [Background technology]

[0002] A common paving method involves laying a roadbed material such as crushed stone on top of a roadbed created by leveling or other means to create a roadbed, and then laying asphalt or concrete as a surface layer. Patent Document 1 describes a method for mixing roller-compacted concrete materials that is excellent in workability and allows for early reopening to traffic. The method involves mixing binder, aggregate, water, and an optional admixture to produce roller-compacted concrete, and the total volume of the binder, aggregate, water, and admixture is 1 m3. 3 The amount of binder contained per B [kg / m 3 ], the total volume of which is 1m 3 The aggregate volume Ag [L / m 3 ], the total volume of which is 1m 3 The amount of water contained per W [kg / m 3 ], and the total volume is 1m 3 The amount of admixture contained per unit Ad [kg / m 3 ] and the relationship between the slump value measured based on JIS A 1101:2014 and the water content W [kg / m 3 ] to the binder amount B [kg / m 3 The present invention describes a method for mixing roller-compacted concrete material, in which the binder, aggregate, water, and admixture are mixed based on a water-binder ratio R, which is the ratio of Furthermore, since on-site generated soil and the like can be used as soil and sand, Patent Document 2 describes a paving material that is environmentally friendly and can be constructed at low cost. The paving material is characterized by being composed of soil and sand, water, and a solidifying agent. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-147850 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-194710 Summary of the Invention [Problem to be solved by the invention]

[0004] On mine roads used by large dump trucks from mining sites to shipping terminals, when the road surface gets wet from rain, it becomes soft and slippery, making it difficult for large dump trucks to pass through. In particular, during the rainy season, it becomes difficult for large dump trucks to pass through for more than half the month, resulting in enormous opportunity losses. Meanwhile, mine roads from mining sites to shipping terminals are only used until mining is completed, and in some cases they may only be used for about one month to one year. Therefore, if the above-mentioned mine roads, etc. are paved with concrete or asphalt, the cost of road maintenance becomes very high, which puts pressure on profits. Furthermore, when vegetation is to be planted on mine roads, etc. after use, the concrete or asphalt paving must be removed, which causes further problems of costs. On the other hand, if soil-based materials other than concrete or asphalt are used for paving in order to reduce costs, there is a problem in that it is difficult to stably obtain the materials. An object of the present invention is to provide a hydraulic composition that can reduce the amount of materials that must be procured from outside and can pave soft ground inexpensively and easily, and a paving method using the hydraulic composition. [Means for solving the problem]

[0005] As a result of extensive research into solving the above problems, the present inventors have found that the above objects can be achieved by a hydraulic composition containing a cementitious binder, fine aggregate, coarse aggregate having an ID2 value of 90 or less as measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability), and water, and having a flow value of 200 to 400 mm, and have completed the present invention. That is, the present invention provides the following [1] to [4]. [1] A hydraulic composition comprising a cementitious binder, fine aggregate, coarse aggregate, and water, wherein at least a portion of the coarse aggregate has an ID2 value of 90 or less as measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability), and the hydraulic composition has a flow value of 200 to 400 mm as measured in accordance with JHS A 313-1992 (Test Method for Aerated Mortar and Aerated Mortar). [2] The hydraulic composition according to [1], wherein the fine aggregate is fine-grained soil.

[0006] [3] A method for paving ground using the hydraulic composition according to [1] or [2], comprising: a soil and sand collection step of collecting soil and sand from ground that is to be paved and has an ID2 value of 90 or less as measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability); a sorting step of classifying the collected soil and sand using a sieve to select the soil and sand that passes through a 5 mm sieve as fine aggregate and the soil and sand that passes through a 40 mm sieve but does not pass through a 5 mm sieve as coarse aggregate having an ID2 value of 90 or less; a preparation step of mixing materials that constitute the hydraulic composition to prepare the hydraulic composition; and a casting step of casting the hydraulic composition to form a pavement surface. [4] The paving method according to [3], further comprising a determination step of measuring the ID2 value of the ground to be paved before the soil and sand collection step, and determining that the ground is a target for paving using the hydraulic composition if the obtained ID2 value is 90 or less, and determining that the ground is not a target for paving using the hydraulic composition if the ID2 value exceeds 90. [Effects of the Invention]

[0007] According to the hydraulic composition of the present invention and the paving method using the hydraulic composition, the amount of materials (aggregates) that must be procured from outside can be reduced, and soft ground can be paved inexpensively and easily. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a flow chart showing an example of a paving method of the present invention. [Figure 2] FIG. 1 is a flow chart showing an example of a paving method of the present invention, which uses forms. DETAILED DESCRIPTION OF THE INVENTION

[0009] The hydraulic composition of the present invention is a hydraulic composition containing a cementitious binder, fine aggregate, coarse aggregate, and water, wherein at least a portion of the coarse aggregate has an ID2 value of 90 or less as measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability), and the hydraulic composition has a flow value of 200 to 400 mm as measured in accordance with JHS A 313-1992 (Test Method for Aerated Mortar and Aerated Mortar). A detailed explanation is provided below.

[0010] In this specification, the cement-based binder refers to a powdery material containing cement as a main material and optionally containing admixtures. Examples of cements used in cement-based binders include various types of Portland cement such as ordinary Portland cement, high-early-strength Portland cement, moderate-heat Portland cement, low-heat Portland cement, and sulfate-resistant Portland cement, as well as blended cements such as blast-furnace cement, fly ash cement, and silica cement, ecocement, white cement, and ultra-rapid-hardening cement. These may be used alone or in combination of two or more. Among these, ordinary Portland cement, high-early-strength Portland cement, and blast-furnace cement are preferred from the viewpoint of strength development and the like. The cement content in the cement binder is preferably 40% by mass or more, more preferably 50 to 95% by mass, even more preferably 60 to 90% by mass, even more preferably 70 to 90% by mass, and particularly preferably 80 to 90% by mass. If the content is 40% by mass or more, the strength (e.g., compressive strength) of the pavement can be increased. Furthermore, if the content is 95% by mass or less, material costs can be reduced and the amount of waste-derived raw materials used can be increased.

[0011] Examples of optional admixtures include finely ground limestone, ground granulated blast furnace slag, gypsum, fly ash, silica fume, quicklime, and slaked lime. These may be used alone or in combination of two or more. Note that the gypsum listed as an admixture is added separately from the gypsum contained in the cement. The proportion of the above admixture in the cementitious binder (the total amount when multiple admixtures are used) is preferably 60% by mass or less, more preferably 5 to 50% by mass, even more preferably 10 to 40% by mass, even more preferably 10 to 30% by mass, and particularly preferably 10 to 20% by mass. If the proportion is 60% by mass or less, the amount of cement is relatively large, and the strength of the pavement (for example, compressive strength) can be increased. In addition, when the cement contained in the cement binder is a mixed cement such as blast furnace cement, cement admixtures such as ground granulated blast furnace slag contained in the mixed cement are considered to be included in the admixtures that can be arbitrarily blended.

[0012] The fine aggregate is not particularly limited, but fine soil is preferred from the viewpoint of ease of availability. Examples of fine-grained soil include expansive clay, shale clay, latosol, marine clay, etc. These may be used alone or in combination of two or more. Furthermore, from the viewpoint of being able to be procured at the paving site and being inexpensive and easily available, it is preferable to use, as at least a part of the fine aggregate contained in the hydraulic composition, fine aggregate (described in detail later) recovered from the ground that is the target of paving and has an ID2 value of 90 or less as measured in accordance with "ASTM D 4644-87 (Standard Test Method for Slake Durability)". Of the total amount of fine aggregate contained in the hydraulic composition, the proportion of fine aggregate recovered from the ground to be paved is preferably 50% by mass or more, more preferably 80% by mass or more, and particularly preferably 100% by mass, from the viewpoints of reducing the amount of fine aggregate that must be procured from outside (places other than the paving site) and making it inexpensive and easy to obtain. The amount of fine aggregate to be mixed is preferably 100 to 700 parts by mass, more preferably 140 to 500 parts by mass, and particularly preferably 180 to 300 parts by mass, relative to 100 parts by mass of the cement binder. If the amount is 100 parts by mass or more, drying shrinkage of the hydraulic composition after hardening can be further suppressed. If the amount is 700 parts by mass or less, the workability of the hydraulic composition before hardening can be further improved.

[0013] At least a portion of the coarse aggregate contained in the hydraulic composition has an ID2 value of 90 or less as measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability). Coarse aggregate with an ID2 value of 90 or less is inexpensive and easily available. Furthermore, from the viewpoint of being procurable at the paving site, being inexpensive, and being easily available, it is preferable to use, as the coarse aggregate having an ID2 value of 90 or less contained in the hydraulic composition, coarse aggregate (described in detail below) recovered from the ground that is the target of paving and has an ID2 value of 90 or less as measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability). Of the total amount of coarse aggregate contained in the hydraulic composition, the proportion of coarse aggregate recovered from the ground to be paved is preferably 50% by mass or more, more preferably 80% by mass or more, and particularly preferably 100% by mass, from the viewpoint that coarse aggregate can be procured at the paving site and is inexpensive and easily available.

[0014] The ID2 value of the coarse aggregate is 90 or less, preferably 26 to 80, and more preferably 51 or more and less than 76, from the viewpoint of cheap and easy availability by procuring it from the ground to be paved at the paving site. If the ID2 value is 26 or more, the strength (e.g., compressive strength) of the pavement can be increased. Of the total amount of coarse aggregate contained in the hydraulic composition, the proportion of coarse aggregate having an ID2 value of 90 or less is preferably 50% by mass or more, more preferably 80% by mass or more, and particularly preferably 100% by mass, from the viewpoint of low cost and easy availability. Furthermore, from the viewpoint of increasing the strength of the pavement, the coarse aggregate may contain coarse aggregate other than the above-mentioned coarse aggregate having an ID2 value of 90 or less. There are no particular limitations on the coarse aggregate other than the coarse aggregate having an ID2 value of 90 or less, and examples thereof include river gravel, mountain gravel, land gravel, sea gravel, etc.

[0015] The amount of coarse aggregate to be mixed is preferably 60 to 300 parts by mass, more preferably 80 to 250 parts by mass, and particularly preferably 120 to 200 parts by mass, relative to 100 parts by mass of the cement binder. If the amount is 60 parts by mass or more, the durability of the set body of the hydraulic composition can be further improved. If the amount is 300 parts by mass or less, the workability (resistance to material separation, etc.) of the hydraulic composition before hardening can be further improved. The fine aggregate ratio is preferably 40 to 55%, more preferably 42 to 53%, and particularly preferably 44 to 51%. The fine aggregate ratio refers to the volume ratio of fine aggregate to the total amount of fine aggregate and coarse aggregate.

[0016] The water is not particularly limited, and examples thereof include tap water and recycled water as specified in "JIS A 5308:2019 (Ready-mixed concrete)". In the hydraulic composition, the mass ratio of water to cement binder (mass of water / mass of cement binder) is preferably 2.0 to 4.0, more preferably 2.1 to 3.5, even more preferably 2.2 to 3.0, and particularly preferably 2.3 to 2.6. If the mass ratio is 2.0 or more, the kneadability of each material and the fluidity of the hydraulic composition are further improved, and the workability during pouring is further improved. If the mass ratio is 4.0 or less, the strength of the pavement can be further increased. In order to increase the strength of the pavement made of the hardened product of the hydraulic composition, the hydraulic composition may contain fibers. Examples of fibers include metal fibers and organic fibers. Among them, in consideration of growing vegetation on the pavement after use or returning the pavement to nature after use, it is preferable to use organic fibers derived from nature, such as wood (pulp) and bamboo.

[0017] The hydraulic composition may contain a cement admixture from the viewpoint of further improving the fluidity before hardening. Examples of cement admixtures include cement dispersants, air-entraining agents, air content adjusters, and setting retarders. Examples of cement dispersants include water-reducing agents, air-entraining water-reducing agents, high-performance water-reducing agents, and high-performance air-entraining water-reducing agents. These may be used alone or in combination of two or more. The amount of cement admixture (when multiple types of cement admixtures are used, the total amount) varies depending on the fluidity and strength development of the target hydraulic composition, but is preferably 0.1 to 5.0 parts by mass, more preferably 0.5 to 4.0 parts by mass, and particularly preferably 1.0 to 3.0 parts by mass relative to the cement binder. If the amount is 0.1 part by mass or more, the fluidity of the hydraulic composition before hardening can be further improved. If the amount is 5.0 parts by mass or less, the cost of the cement admixture can be reduced.

[0018] The hydraulic composition has a flow value of 200 to 400 mm, preferably 220 to 350 mm, more preferably 240 to 320 mm, and particularly preferably 250 to 300 mm, measured in accordance with the Japan Highway Public Corporation standard "JHS A 313-1992 (Test Method for Aerated Mortar and Aerated Mortar)." If the flow value is less than 200 mm, workability is reduced, for example, it becomes difficult to discharge from a concrete mixer truck or the like. If the flow value exceeds 400 mm, when formwork is used to cast pavement, the hydraulic composition before hardening may leak from gaps in the formwork, or construction may be impossible if the ground is sloping. In addition, the durability of the hydraulic composition after hardening is reduced.

[0019] The hydraulic composition can be prepared by determining the amounts of cement binder, fine aggregate, coarse aggregate, water, etc. to achieve the target flow value of the hydraulic composition (flow value measured in accordance with "JHS A 313-1992 (Test Methods for Air Mortar and Air Milk)"), and then mixing (kneading) the materials that make up the hydraulic composition. Before determining the above blending amounts, the moisture content of the aggregates (fine aggregate and coarse aggregate) may be measured and used as an index for determining the blending amounts of the materials (particularly the blending amount of water). The mixing (kneading) means is not particularly limited, and examples thereof include a concrete plant, a tilting mixer, a concrete mixer truck, etc. Among these, a concrete mixer truck is preferred from the viewpoint of being able to mix at the paving site. In this specification, the term "hydraulic composition" includes both a fluid form before hardening and a form after hardening.

[0020] An example of a method for paving ground using the above-mentioned hydraulic composition includes a paving method including a soil recovery step of recovering soil and sand from ground that is to be paved and has an ID2 value of 90 or less as measured in accordance with "ASTM D 4644-87 (Standard Test Method for Slake Durability)", a sorting step of classifying the recovered soil and sand using a sieve to select soil and sand that passes through a 5 mm sieve as fine aggregate and soil and sand that passes through a 40 mm sieve but does not pass through a 5 mm sieve as coarse aggregate having an ID2 value of 90 or less, a preparation step of mixing materials that constitute the hydraulic composition to prepare the hydraulic composition, and a casting step of casting the hydraulic composition to form a pavement surface. Each step will be described in detail below with reference to FIGS.

[0021] [Soil collection process] This process involves recovering soil 3 from ground 1, which is the target of paving and has an ID2 value of 90 or less as measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability). The means for recovering earth and sand from the ground is not particularly limited, and examples thereof include a wheel loader and a backhoe. In the present invention, the ID2 value of the ground 1 to be paved is 90 or less, preferably 26 to 80, and more preferably 51 or more and less than 76. When the ID2 value exceeds 90, the ground strength (e.g., compressive strength) is sufficiently high, making paving the ground less necessary. Furthermore, because the ground has excellent resistance to slaking, even if soil and sand are collected from the ground and then classified using a 5 mm mesh sieve, the amount of soil and sand that passes through the sieve is small, and it may be impossible to obtain a sufficient amount of selected aggregate (especially fine aggregate). In this case, it becomes necessary to transport aggregate from a location other than the paving site to the paving site.

[0022] Furthermore, the ground to be paved is preferably one where slaking has occurred, from the viewpoint of a high need for paving. As a result of slaking occurring in the ground, fine-grained earth and sand (fine-grained soil) is generated, and by classifying the earth and sand collected from the ground, a sufficient amount of fine aggregate (fine-grained soil) that can be used as a material for the hydraulic composition of the present invention can be obtained. Furthermore, when recovering the soil and sand that forms the surface layer of ground where slaking has occurred, by using the area where slaking has not occurred (area with high strength) as the surface layer and using this surface layer as the roadbed, it is possible to omit the ground improvement process that is carried out as needed before paving, thereby simplifying the work. In addition, ground with an ID2 value of 90 or less is prone to slaking.

[0023] Before the soil and sand collection step, a determination step may be carried out in which the ID2 value of the ground to be paved is measured in accordance with "ASTM D 4644-87 (Standard Test Method for Slake Durability)" and if the obtained ID2 value is 90 or less, the ground is determined to be a target for paving using the hydraulic composition of the present invention, and if the ID2 value exceeds 90, the ground is determined not to be a target for paving using the hydraulic composition of the present invention. By providing a judgment process, it is possible to judge whether the ground requires paving and whether the above-mentioned fine aggregate and coarse aggregate can be obtained sufficiently from the soil and sand recovered from the ground.

[0024] [Sorting process] This process involves classifying the collected soil and sand 3 using a sieve 4, selecting the soil and sand that passes through a sieve with a mesh size of 5 mm as fine aggregate 5, and selecting the soil and sand that passes through a sieve with a mesh size of 40 mm but not a sieve with a mesh size of 5 mm as coarse aggregate 6 with an ID2 value of 90 or less. By classifying the soil and sand 3 collected from the ground 1, fine aggregate 5 and coarse aggregate 6 that can be used as materials for hydraulic compositions can be obtained. In addition, soil and sand that does not pass through a sieve with 40 mm openings can be crushed using a bucket or the like, and the crushed material can be classified again using a sieve. [Preparation process] This step is a step of preparing the hydraulic composition 8 by mixing the materials constituting the hydraulic composition described above. The materials constituting the hydraulic composition are the materials contained in the hydraulic composition described above (specifically, cementitious binders, fine aggregates, coarse aggregates at least a part of which has an ID2 value of 90 or less when measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability)), and water, etc.). From the viewpoint of reducing the amount of materials that must be procured from outside and reducing the cost of aggregates (fine aggregate and coarse aggregate), it is preferable that the total amount of aggregates (fine aggregate and coarse aggregate) contained in hydraulic composition 8 be the aggregates (fine aggregate 5 and coarse aggregate 6) obtained in the above-mentioned sorting step. Furthermore, from the viewpoint of increasing the strength of the pavement, coarse aggregate other than the coarse aggregate 6 obtained in the above-mentioned selection step may be used as part of the coarse aggregate. The materials are mixed using a mixing means 7 such as a concrete mixer truck, a complete plant, or a tilting mixer.

[0025] [Pouring process] This step is a step of forming a pavement surface 9 by pouring a hydraulic composition 8 . In Fig. 1, the hydraulic composition 1 is poured into a recess 2 that is formed after excavating the ground 1 in the soil recovery process. The recess 2 may be formed by excavating a depth corresponding to the required thickness of the pavement. By forming the recess 2, the pavement can be constructed without using forms. In Fig. 2, a formwork 10 is placed on the ground 1, and a hydraulic composition is poured into the formwork 10. The ground 1 in Fig. 2 has had all of the soil and sand on the surface of the ground removed using a wheel loader, so no depressions have been formed in the ground 1. After the hydraulic composition 8 is cast, the hydraulic composition 8 may be spread evenly, then compacted using a vibrator or the like, and further the top surface of the pavement surface 9 may be leveled (surface finished). Examples of methods for leveling the pavement surface 9 include mechanical methods using a finisher, simple finisher, surface finishing machine, etc., and manual methods using a trowel, template tamper, float, etc.

[0026] Before pouring, the ground may be compacted flat and evenly to form the roadbed (a layer of about 1 cm thickness located under the pavement) or road body (the ground itself located at the bottom of the road structure). Also, a roadbed made of roadbed material may be formed between the roadbed or road body and the pavement. The roadbed or road body preferably has a strength sufficient to support the mass of a vehicle such as a large dump truck, etc. The CBR (subgrade soil bearing capacity ratio) of the roadbed or road body is preferably 5 or more, more preferably 10 or more, even more preferably 15 or more, and particularly preferably 30 or more, from the viewpoint of being able to sufficiently support the mass of a vehicle such as a large dump truck, etc. When the roadbed or road body does not have sufficient strength (for example, when the CBR value is less than 5), or when paving areas that require compressive strength, bending strength, and abrasion resistance, such as areas that form curves in the road or areas at the bottom of slopes, the thickness of the pavement can be increased. Also, concrete can be poured after reinforcing bars have been placed on the ground. The thickness of the pavement is designed based on the expected period of use and economic efficiency of the pavement, and in the present invention, although it differs depending on the shape of the road and the desired strength, it is preferably 5 to 70 cm, more preferably 10 to 60 cm. The hydraulic composition of the present invention exhibits sufficient strength within 72 hours at the earliest after casting, allowing roads to be opened to the public at an early stage. The pavement, which is a hardened product of the hydraulic composition of the present invention, can be returned to nature by weathering after use. [Example]

[0027] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. [Materials used] (1) Cement-based binder A: containing ordinary Portland cement and fly ash, ordinary Portland cement content: 80% by mass or more (2) Cement-based binder B: containing ordinary Portland cement, slaked lime, and granulated blast furnace slag, with ordinary Portland cement content of 55% by mass or more (3) Cement-based binder C: ordinary Portland cement, blast furnace slag powder, and gypsum, ordinary Portland cement content: 70% by mass or more (4) AE water reducer: GCP Chemicals, trade name "Darasem M-7" (5) Coarse aggregate A; sandstone

[0028] [Example 1, Comparative Example 1] The ID2 value of the ground to be paved was measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability), and the value (82) was classified as "high." The soil was excavated using a backhoe to form a depression 50 cm deep (the target thickness of the pavement). The CBR value of the roadbed portion of the depression was 45. The soil and sand recovered by excavation was classified using a sieve with 40 mm openings, and the soil and sand that passed through the 40 mm opening sieve was further classified using a 5 mm opening sieve. The soil and sand that passed through the 40 mm opening sieve but not the 5 mm opening sieve was selected as coarse aggregate, and the soil and sand that passed through the 40 mm opening sieve and the 5 mm opening sieve was selected as fine aggregate. The ID2 of the selected coarse aggregate was measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability). The ID2 value of the coarse aggregate was the same as that of the ground to be paved (82).

[0029] Cement binder A, selected aggregates (fine aggregate and coarse aggregate), water, and an AE water-reducing agent were mixed (kneaded) in the proportions shown in Table 1 using a concrete plant to prepare a hydraulic composition, which was then transferred to a concrete mixer truck. The blending amounts are determined so that the flow value of the hydraulic composition falls within a desired range after measuring the moisture content of the selected aggregates (fine aggregate and coarse aggregate). A hydraulic composition was poured into the recessed portion from a concrete mixer truck and then cured at 28°C to produce a pavement made of a hardened hydraulic composition. The flow value of the hydraulic composition was measured in accordance with "JHS A 313-1992 (Testing method for air mortar and air mortar)". In addition, specimens were cut out from the pavement 7 days after pouring and from the pavement 3 months after pouring, and the compressive strength of the specimens was measured in accordance with ASTM C39 (Test method for compressive strength of cylindrical concrete specimens).

[0030] The obtained hydraulic compositions and the measurement results were used to carry out the following evaluations. [Evaluation of workability] The concrete was rated as "◎" when it could be easily discharged from a mixing (mixing) means such as a concrete mixer truck or a tilting mixer, and poured easily, without dripping; "〇" when it could be discharged from the mixing means and poured easily, without dripping; "△" when it was difficult to discharge from the mixing means, or when it was easy to discharge but had too much fluidity, causing leakage from the formwork into which it was poured or making construction on sloped areas difficult; and "×" when it could not be discharged from the mixing means. [Durability evaluation] The rate of decrease in compressive strength was calculated from the compressive strength 7 days after pouring and the compressive strength 3 months after pouring, and the rate of decrease was evaluated as "◎" if the rate of decrease was 10% or less, "〇" if the rate of decrease was more than 10% and less than 20%, "△" if the rate of decrease was more than 20% and less than 30%, and "×" if the rate of decrease was more than 30%. The results are shown in Table 2.

[0031] [Example 2, Comparative Example 2] The ID2 value of the ground to be paved (ground that had become softened due to slaking) was measured in accordance with ASTM D 4644-87 (Standard Test Method for Slaking Durability), and the value (35) was classified as "low." The upper layer of the ground was removed using a wheel loader and the soil was recovered. The CBR value of the ground (subgrade) from which the upper layer was removed was 18. The removed soil was classified using a sieve with 40 mm openings, and the soil that passed through the 40 mm openings was further classified using a 5 mm openings sieve. The soil that passed through the 40 mm openings sieve but not the 5 mm openings sieve was selected as coarse aggregate, and the soil that passed through the 40 mm openings sieve and the 5 mm openings sieve was selected as fine aggregate. The ID2 of the selected coarse aggregate was measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability). The ID2 value of the coarse aggregate was the same as that of the ground to be paved (35).

[0032] Cement binder B, selected aggregates (fine aggregate and coarse aggregate), water, and an AE water-reducing agent were mixed (kneaded) using a tilting mixer in the amounts shown in Table 1 to prepare hydraulic compositions. The blending amounts are determined so that the flow value of the hydraulic composition falls within a desired range after measuring the moisture content of the selected aggregates (fine aggregate and coarse aggregate). The hydraulic composition was poured from a tilting mixer into a formwork installed on the ground (subgrade) from which the upper layer had been removed, and then cured at 28°C to produce a pavement consisting of a hardened hydraulic composition. The flow value and the like of the hydraulic composition were measured in the same manner as in Example 1. The obtained hydraulic composition was also evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0033] [Example 3, Comparative Example 3] The ID2 value of the ground to be paved (ground that had slaking and become softened) was measured in accordance with ASTM D 4644-87 (Standard Test Method for Slaking Durability), and the value (57) was classified as "medium." As in Example 2, the soil and sand were collected and then classified. The soil and sand that passed through a sieve with a mesh size of 40 mm but not a sieve with a mesh size of 5 mm was selected as coarse aggregate, and the soil and sand that passed through a sieve with a mesh size of 40 mm and a sieve with a mesh size of 5 mm was selected as fine aggregate. The ID2 of the selected coarse aggregate was measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability). The ID2 value of the coarse aggregate was the same as that of the ground to be paved (57).

[0034] Cement binder C, selected aggregates (fine aggregate and coarse aggregate), coarse aggregate A, water, and an AE water-reducing agent were mixed (kneaded) using a concrete mixer truck in the proportions shown in Table 1 to prepare a hydraulic composition. The blending amounts are determined so that the flow value of the hydraulic composition falls within a desired range after measuring the moisture content of the selected aggregates (fine aggregate and coarse aggregate). The hydraulic composition was poured from a concrete mixer truck into a formwork set on the ground (roadbed) from which the upper layer had been removed, and then cured at 28°C to produce a pavement consisting of a hardened hydraulic composition. The flow value and the like of the hydraulic composition were measured in the same manner as in Example 1. The obtained hydraulic composition was also evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0035] [Table 1]

[0036] [Table 2]

[0037] It can be seen from Table 2 that the hydraulic compositions of Examples 1 to 3 are excellent in workability and durability. In Comparative Example 1, it was difficult to discharge the hydraulic composition from the concrete mixer truck, and construction could not be carried out. In Comparative Example 2, it was possible to cast the hydraulic composition from the tilting mixer, but there were problems such as the hydraulic composition leaking from gaps in the formwork and difficulty in construction on sloped sections. In addition, the reduction rate of compressive strength was 66.6%, indicating low durability. In Comparative Example 3, it was possible to cast the hydraulic composition from a concrete mixer truck, but there were problems such as the hydraulic composition leaking from gaps in the formwork and difficulty in construction on sloped areas. In addition, the reduction rate of compressive strength was 34.2%, indicating low durability. [Explanation of symbols]

[0038] 1 ground 2 recesses 3. Sediment 4 sieve 5 Fine aggregate 6 Coarse aggregate 7 Mixing means 8 Hydraulic composition 9. Pavement 10 Formwork

Claims

1. A hydraulic composition for ground paving, comprising a cement binder, fine aggregate, coarse aggregate, and water, The ID measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability) of the total amount of coarse aggregate ２ The proportion of coarse aggregate having a value of 90 or less is 50% by mass or more, The amount of the fine aggregate mixed relative to 100 parts by mass of the cement-based binder is 140 to 300 parts by mass, The amount of the coarse aggregate mixed relative to 100 parts by mass of the cement-based binder is 80 to 200 parts by mass, The hydraulic composition for ground paving is characterized in that the flow value of the hydraulic composition for ground paving measured in accordance with "JHS A 313-1992 (Testing method for air mortar and air mortar)" is 220 to 320 mm.

2. 2. The hydraulic composition for ground paving according to claim 1, wherein said fine aggregate is fine-grained soil.

3. A method for paving ground using the hydraulic composition for ground paving according to claim 1 or 2, comprising: The ID of the pavement is measured in accordance with ASTM D 4644-87 (Standard Test Method for Slake Durability). ２ a soil recovery process of recovering soil from the ground where the value of is 90 or less; The collected soil and sand are classified using a sieve, and the soil and sand that passes through a sieve with a mesh size of 5 mm is selected as the fine aggregate, and the soil and sand that passes through a sieve with a mesh size of 40 mm but does not pass through a sieve with a mesh size of 5 mm is selected as the ID aggregate. ２ a sorting step of sorting the aggregate into coarse aggregate having a value of 90 or less; a preparation step of mixing materials constituting the hydraulic composition for ground paving to prepare the hydraulic composition for ground paving; a casting step of casting the hydraulic composition for ground paving to form a paved surface; A paving method including:

4. Before the soil recovery process, the ID of the ground to be paved is ２ Measure the value of The above ID obtained ２ If the value is 90 or less, the ground is used as an object for paving using the hydraulic composition for ground paving, and ２ 4. The paving method according to claim 3, further comprising a determining step of determining that the ground is not a target for paving using the hydraulic composition for ground paving when the numerical value of exceeds 90.

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