Laying layer with upper surface formed of hydrated cured body and method of constructing the same

Abstract

To provide a construction method capable of inexpensively and efficiently constructing a laying layer with its upper surface formed of a hydrated cured body, capable of functioning as a substitute for leveling concrete.SOLUTION: In a method of constructing, on the ground, a laying layer with its upper surface formed of a hydrated cured body, a coarse aggregate layer (a) is provided on the ground, and paste (p) using cement as a binder thereover is layed to fill at least a void part in an upper side region of the coarse aggregate layer (a) with the paste (p) to form paste filling parts ap filled with the paste and to bury an upper face of the coarse aggregate layer (a) in the paste (p) to cure the paste (p) as it is, to form a hydrated cured body. Since an amount of cement only functionally necessary is used, an amount of cement, an amount of laid paste, and the number of construction man-hours can be reduced relative to leveling concrete, and since a surface of the laid layer is a paste surface without containing coarse aggregate, the surface can easily be finished.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a laying layer whose upper surface is made of a hydrated hardened body, which can be used as a substitute for basal concrete (hereinafter referred to as "basal concrete"), and a method for constructing the same. Generally, basal concrete refers to concrete that is poured on the ground (including a layer of compacted crushed stone on the ground; the same applies below) for leveling, marking out, and constructing forms prior to the foundation work of a building structure, but in this application, the term basal concrete is used to collectively refer to unreinforced concrete poured on the ground, including so-called concrete floors. [Background technology]

[0002] Prior to the construction of the foundations of a building structure, a basal concrete layer is laid to level the ground, mark out, and construct the formwork. This basal concrete layer is poured onto the ground to a thickness of approximately 50 mm. Generally, marking is done the day after the basal concrete layer is laid, and the formwork is constructed the day after that. For this reason, the basal concrete layer must have a flat top surface, be able to be marked out the day after it is poured, be able to be used to drive concrete nails (hereafter referred to as "nails") to fasten the formwork (battens) the day after that, and have enough nail holding strength to hold the formwork in place. Unlike concrete for structures, there are no official standards or regulations regarding the quality of concrete for concrete for construction. 2 In many cases, ready-mix concrete is conventionally used.

[0003] Furthermore, with the aim of achieving carbon neutrality, there is a growing demand for reducing CO2 emissions in construction work. In concrete construction, focusing on the CO2 generated during cement production, blast furnace cement, in which part of the cement is replaced with ground granulated blast furnace slag, is sometimes used. Blast furnace cement is known for its advantages, such as sustained strength development over a long period of time, low heat of hydration, high chemical resistance, and excellent durability. However, Patent Document 1 states that blast furnace slag has a property of gradually hydrating due to the stimulation of calcium hydroxide produced by the hydration of clinker minerals (latent hydraulicity), resulting in poorer initial strength development compared to cement. According to Patent Document 1, the compressive strength at 3 days (initial stage) of JIS mortar (before the 1997 revision) using a composition in which ordinary Portland cement is gradually replaced with blast furnace cement decreases significantly with the addition of more blast furnace slag. Furthermore, when the amount of blast furnace slag added is 70%, the strength development is only about 30 to 35% of that of plain steel, so simply increasing the amount of blast furnace slag added is problematic because it reduces the initial strength development.

[0004] Therefore, Patent Document 1 proposes a powdered mixed cement composition containing cement clinker powder, ground granulated blast furnace slag, and limestone powder in order to improve the delay in early strength development, in which, relative to a total of 100% by mass of the cement clinker powder, ground granulated blast furnace slag, and limestone powder, the proportion of cement clinker powder is 47 to 59% by mass, the proportion of ground granulated blast furnace slag powder is 22 to 43% by mass, and the proportion of limestone powder is 4 to 23% by mass, and the proportion of an aluminate phase in the cement clinker powder is more than 13% by mass and not more than 17% by mass. Furthermore, Patent Document 2 proposes rapid-hardening cement, but the amount of ground granulated blast furnace slag added here is 50% or less, as in Patent Document 1. This document states that if the amount of ground granulated blast furnace slag mixed is too high, the proportions of rapid-hardening admixture and cement will decrease relatively, which may result in a decrease in early strength development and long-term strength development.

[0005] Patent Document 3 proposes a method for producing high-strength mortar or high-strength concrete that exhibits high fluidity, low viscosity, and fire resistance at a low water-binder ratio. In this method, 5 to 30% of the binder, such as cement, is replaced with ground granulated blast furnace slag and / or ground granulated fly ash. The water-binder ratio is preferably 17.5 to 25%. Furthermore, Patent Document 4 specifies that the replacement rate of ground granulated blast furnace slag relative to the weight of cement should be 60% or more. In order to activate the hydration reaction of the ground granulated blast furnace slag, nitrite and diethanol isopropanolamine are added, and gypsum or calcium carbonate may also be added. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-254909 [Patent Document 2] Japanese Patent Publication No. 2021-160994 [Patent Document 3] Patent Publication No. 2021-075409 [Patent Document 4] Japanese Patent Publication No. 2020-138874 Summary of the Invention [Problem to be solved by the invention]

[0007] The present inventors have investigated the problems of the prior art and have found that the disposable containers that have been widely used up until now have the following problems. (i) Disposable concrete is used for leveling, marking out, and constructing formwork when constructing the foundation of a structure, and does not necessarily require the performance required of concrete used in structures, so there is room for reducing specifications and costs. (ii) Generally, basal concrete is constructed to a thickness of about 50 mm, but when battens are fixed with nails to construct formwork, the nails only penetrate about 15 to 30 mm into the basal concrete. Therefore, the thickness of the basal concrete layer (concrete layer) to hold the nails is thought to be a maximum of about 30 mm, and there is room for it to be thinner.

[0008] (iii) In conventional technology, when replacing cement with ground granulated blast furnace slag to reduce CO2 emissions, a replacement rate of 50% or less is considered practical due to the low initial strength development. This is because a replacement rate of ground granulated blast furnace slag exceeding 50% requires the use of more admixtures (e.g., expensive high-performance air-entraining water-reducing agents and thickeners) and mineral admixtures to compensate for the delayed initial strength development, which requires more sophisticated mixing control and increases costs. However, because the basal concrete must be easy to nail and able to hold the nails once driven, it is better for the concrete to be low in strength during the nailing stage (i.e., the initial stage), and only needs to be strong enough to hold the nails that secure the battens. High concrete strength makes nailing difficult, while high strength can cause the surface layer of the basal concrete to peel off and fly apart due to the impact of nailing. Furthermore, when nailing into mortar, the nails hit the coarse aggregate on the surface, so unless the nails are strong and the nailing skill is high, it becomes difficult to drive the nails, and there is also a risk that the surrounding mortar will peel off and fly off.

[0009] The present invention has been made in light of the above-mentioned problems of the prior art and aims to solve these problems, and aims to provide a laying layer that can be used as an alternative to basal concrete and can be constructed efficiently at low cost, and a construction method thereof. Another object of the present invention is to provide a laying layer and a construction method thereof that (i) effectively utilizes by-products of the steel manufacturing process and contributes to reducing CO2 emissions, (ii) is easy to install, and (iii) when nailing into a foundation marking surface, allows for easy nailing and provides appropriate nail holding power. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, the present invention is characterized in that coarse aggregate is laid on the ground to form a coarse aggregate layer, and then a required amount (for example, an amount required for nailing) of paste made of cement slurry or mortar is poured on top of the coarse aggregate layer, the paste is filled into at least the upper region of the coarse aggregate layer, and the upper surface of the coarse aggregate layer is buried in the paste, thereby obtaining a laying layer whose upper surface is made of a hydrated hardened body (hardened paste). This means that only the amount of paste required for functionality needs to be poured, which reduces the amount of cement and paste required compared to basing concrete, and also eliminates the need for processes for mixing, managing, and preparing ready-mix concrete. Furthermore, since the surface of the laid layer (the outermost layer) is a paste surface that does not contain coarse aggregate, it is easy to finish the surface. For these reasons, a basing layer that replaces basing concrete can be constructed efficiently and at low cost.

[0011] Furthermore, the present invention can have the following configurations to solve further problems. Specifically, a paste layer of a predetermined thickness can be provided on a coarse aggregate layer to improve the workability of surface finishing and facilitate nailing. Furthermore, to reduce CO2 emissions and delay the development of early strength to facilitate nailing, a portion of the cement constituting the paste can be replaced with ground granulated blast furnace slag at a high substitution rate. Furthermore, to reduce the use of natural resources and improve nail holding power, a portion or all of the natural fine aggregate constituting the paste can be replaced with fine blast furnace slag aggregate. Furthermore, to solve problems such as improving workability, facilitating nailing and ensuring nail holding power, the depth of the paste filling portion in the coarse aggregate layer, the weight ratio of binder to water in the paste, and the weight ratio of binder to fine aggregate can be optimized.

[0012] That is, the gist of the present invention for solving the above problems is as follows. [1] A method for constructing a laying layer on the ground, the upper surface of which is made of a hydrated hardened body, Coarse aggregate is laid on the ground to form a coarse aggregate layer (a), and then paste (p) containing cement as a binder (including paste in which part of the cement is replaced with ground granulated blast furnace slag) is poured on top of the coarse aggregate layer (a), filling the voids in at least the upper region of the coarse aggregate layer (a) with the paste (p) to form a paste-filled portion (a p ) and burying the top surface of the coarse aggregate layer (a) in paste (p), and solidifying the paste (p) in this state to form a hydrated hardened body. [2] In the construction method of [1] above, the paste filling portion (a) of the coarse aggregate layer (a) p A method for constructing a laying layer whose upper surface is made of a hydrated hardened body, characterized in that the average thickness of the layer is 2 / 5 or more of the maximum dimension of the coarse aggregate.

[0013] [3] In the construction method of [1] or [2] above, the paste (p) is poured to form a paste layer (p) having an average thickness of 10 mm or more and 30 mm or less on the coarse aggregate layer (a). L A method for constructing a laying layer having an upper surface made of a hydrated hardened body, characterized in that [4] A method for constructing a laying layer having an upper surface made of a hydrated hardened body, characterized in that in any of the construction methods [1] to [3] above, the paste (p) is a binder in which 50% to 70% of the cement weight is replaced with granulated blast furnace slag. [5] A method for constructing a laying layer having an upper surface made of a hydrated hardened body, in any of the construction methods [1] to [4] above, characterized in that the weight ratio of binder to water (binder:water) of the paste (p) is 1:0.5 to 0.6. [6] A method for constructing a laying layer having an upper surface made of a hydrated hardened body, in any of the construction methods [1] to [5] above, characterized in that the paste (p) is mortar and the weight ratio of binder to fine aggregate is 1:3 to 5.

[0014] [7] A method for constructing a laying layer having an upper surface made of a hydrated hardened body, in any of the construction methods [1] to [6] above, characterized in that the paste (p) is mortar and 50% by weight or more of the fine aggregate is blast furnace slag fine aggregate. [8] In any of the construction methods [1] to [7] above, the paste (p) is a mortar, in which 50% to 70% of the cement weight is replaced with blast furnace slag ground powder as a binder, and 50% by weight or more of the fine aggregate is blast furnace slag fine aggregate; The placed paste (p) forms a paste layer (p) with an average thickness of 10 mm to 30 mm on top of the coarse aggregate layer (a). L ) is formed, The paste filling part (a) is only in the upper side area of ​​the coarse aggregate layer (a). p ) is formed, and the paste filling portion (a p A method for constructing a laying layer whose upper surface is made of a hydrated hardened body, characterized in that the average thickness of the layer is 2 / 5 or more of the maximum dimension of the coarse aggregate.

[0015] [9] In any of the construction methods [1] to [8] above, the paste (p) is a paste to which a chemical admixture containing a lignin sulfonate compound and a polycarboxylic acid ether as components is added in an amount of 0.5% to 1% of the binder weight, and the weight ratio of the binder to the total of water and chemical admixture (binder:water+chemical admixture) is 1:0.45 to 0.54.

[10] In any of the construction methods [1] to [9] above, the paste (p) is mortar, the fine aggregate is blast furnace slag fine aggregate, and further, 20±5% of the binder weight of blast furnace slag powder is added as an admixture.

[11] A method for constructing a laying layer in any one of the above-mentioned [1] to

[10] , wherein the upper surface of the laying layer is made of a hydrated hardened body, and the upper surface of the laying layer is a foundation marking surface.

[0016]

[12] A laying layer constructed on the ground, the upper surface of which is made of a hydrated hardened body, The coarse aggregate layer (A) is constructed by spreading coarse aggregate on the ground, and a hydrated hardened body using cement as a binder (including a hydrated hardened body in which part of the cement is replaced with ground granulated blast furnace slag). The hydrated hardened body filling part (A) is filled in the voids in at least the upper region of the coarse aggregate layer (A). p) and has a hydrated hardened body (B) in which the upper surface of the coarse aggregate layer (A) is buried.

[13] In the laying layer of the above

[12] , the hydrated hardened body filling part (A p A laying layer whose upper surface is made of a hydrated hardened body, characterized in that the average thickness of the layer is 2 / 5 or more of the maximum dimension of the coarse aggregate.

[0017]

[14] In the laying layer of the above

[12] or

[13] , a hydrated hardened body layer (B) having an average thickness of 10 mm or more and 30 mm or less is laid on the coarse aggregate layer (A). L A laying layer having an upper surface made of a hydrated hardened body, characterized in that a hydrated hardened body is formed.

[15] In any of the laying layers

[12] to

[14] above, the hydrated hardened body (B) is a laying layer whose upper surface is made of a hydrated hardened body, characterized in that 50% to 70% of the cement weight is replaced with ground granulated blast furnace slag as a binder.

[16] In any of the above-mentioned

[12] to

[15] laying layers, the hydrated hardened body (B) is mortar, and 50% by weight or more of the fine aggregate is blast furnace slag fine aggregate.

[0018]

[17] In any of the laying layers

[12] to

[16] above, the hydrated hardened body (B) is mortar, in which 50% to 70% of the cement weight is replaced with blast furnace slag fine powder as a binder, and 50% by weight or more of the fine aggregate is blast furnace slag fine aggregate; A layer of coarse aggregate (A) is covered with a layer of hydrated hardened material (B) with an average thickness of 10 mm to 30 mm. L ) is formed, The hydrated hardened mass filling section (A) is placed only in the upper area of ​​the coarse aggregate layer (A). p ) is formed, and the hydrated hardened body filling part (A p A laying layer whose upper surface is made of a hydrated hardened body, characterized in that the average thickness of the layer is 2 / 5 or more of the maximum dimension of the coarse aggregate.

[18] In the laying layer of any one of the above

[12] to

[17] , the upper surface of the laying layer is a foundation marking surface, and the upper surface of the laying layer is made of a hydrated hardened body. [Effects of the Invention]

[0019] According to the construction method of the present invention, a coarse aggregate layer (a) is laid on the ground, and a required amount of paste (p) containing cement as a binder is poured on top of the layer. The paste (p) is then filled into at least the upper region of the coarse aggregate layer (a), and the top surface of the coarse aggregate layer (a) is submerged in the paste (p), resulting in a laying layer whose top surface is a hydrated hardened body (hardened paste (p)). Therefore, only the amount of paste (p) required for functionality is poured, reducing the amount of cement, paste pouring volume, and construction labor compared to pre-mixed concrete. Furthermore, with pre-mixed concrete, strict mix control is required to prevent problems such as separation of the paste and coarse aggregate. Furthermore, the use of blast furnace slag powder or fine blast furnace slag aggregate requires more strict mix control and expensive admixtures. In contrast, the present invention does not use pre-mixed concrete, eliminating the need for such strict mix control and the use of expensive admixtures. Furthermore, the surface (outermost layer) of the laying layer is a paste surface that does not contain coarse aggregate, making it easy to finish. As described above, according to the present invention, a laying layer that replaces basal concrete can be constructed at low cost and efficiently.

[0020] In the present invention, a paste layer p having a predetermined thickness is formed on the coarse aggregate layer a. L By providing this, nailing can be easily performed when nailing to the foundation marking surface, and the paste layer necessary for nail retention can be secured, improving the ease of nailing work. L By providing this, the workability of the surface finish can also be improved. Furthermore, in the present invention, by replacing a portion of the cement constituting the paste p with ground granulated blast furnace slag at a high substitution rate, it is possible to effectively utilize by-products of the steel manufacturing process and reduce CO2 emissions. Furthermore, by delaying the development of early strength, it is possible to improve the ease of nailing when nailing. The laying layer used as a replacement for basting concrete must be able to be marked out the day after construction and then nailed to secure the battens the day after that. However, if the strength is too high, nailing becomes difficult, and if the strength is too low, nails cannot be held. In the present invention, by replacing a portion of the cement with ground granulated blast furnace slag at a high substitution rate, the development of early strength is delayed, improving the ease of nailing, while still achieving the necessary and sufficient nail holding power. Furthermore, even if the development of early strength is delayed, sufficient strength is achieved in the long term, so there is no problem with the strength of the hydrated hardened body of the laying layer. Furthermore, in the present invention, the paste p in which part of the cement is replaced with ground granulated blast furnace slag at a high replacement rate is soft and viscous but not sticky, so the paste p does not stick to the trowel during surface finishing, which has the advantage of making it easy to work with when leveling. In addition to replacing part of the cement constituting the paste p with ground granulated blast furnace slag at a high substitution rate as described above, a paste layer p of a predetermined thickness is formed on the coarse aggregate layer a. L When this layer is provided, the above-mentioned effects can be obtained, making it a particularly preferable laying layer when nailing to a foundation marking surface.

[0021] In addition, in the present invention, by using blast furnace slag fine aggregate as part or all of the fine aggregate constituting the paste p, it is possible to effectively utilize by-products of the steel manufacturing process and reduce the use of natural aggregate (natural resources). Furthermore, when nailing, the friction between the hardened mortar and the nail is higher than when natural fine aggregate is used, thereby increasing the holding power of the nail. In the present invention, the paste filling portion a in the coarse aggregate layer a pBy optimizing the thickness of the paste p, the weight ratio of binder to water in the paste p, and the weight ratio of binder to fine aggregate, etc., it is possible to obtain effects such as high workability, and when nailing, high workability for nailing can be obtained while also ensuring nail holding power (i.e., high degree of compatibility between workability for nailing and ensuring nail holding power can be achieved). The laying layer of the present invention is obtained by the construction method of the present invention described above, and comprises a coarse aggregate layer A laid on the ground, and a hydrated hardened body B using cement as a binder, which fills at least the upper region of the coarse aggregate layer A and buries the upper surface of the coarse aggregate layer A. Therefore, effects similar to those of the method of the present invention described above can be obtained. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a longitudinal cross-sectional view schematically showing a state in which a coarse aggregate layer a is formed on the ground in one embodiment of the method of the present invention. [Figure 2] FIG. 2 is a longitudinal cross-sectional view schematically showing a state in which a paste p is poured into the coarse aggregate layer a of FIG. 1 and the paste p is filled into all voids in the coarse aggregate layer a in a different embodiment of the method of the present invention. [Figure 3] FIG. 2 is a longitudinal cross-sectional view schematically showing a state in which a paste p is poured into the coarse aggregate layer a of FIG. 1 and the paste p is filled only in voids in the upper region of the coarse aggregate layer a in a different embodiment of the method of the present invention. [Figure 4] FIG. 3(A) is a longitudinal cross-sectional view showing the laying layer obtained in the embodiment of FIG. 3(A) and the state in which battens are fixed to the upper surface of the laying layer by nailing. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention is a method for constructing a laying layer on the ground, the upper surface of which is made of a hydrated hardened body. Typical examples of such laying layers include, but are not limited to, laying layers that have traditionally been constructed with basal concrete when constructing foundations for architectural structures (laying layers for leveling, marking, and formwork construction). In other words, in addition to such laying layers, the present invention also includes laying layers that serve as a substitute for basal concrete constructed on the ground when constructing foundation beams, earthen floors, etc. Furthermore, it also includes laying layers that serve as a substitute for earthen floor concrete. Therefore, the laying layer constructed by the present invention can be a substitute for any type of unreinforced concrete (i.e., concrete that does not require structural strength) constructed on the ground. Below, we will explain an embodiment of the method of the present invention, mainly using as an example the case of constructing a laying layer (a laying layer for leveling, marking out, and constructing formwork) that has traditionally been constructed using basing concrete when building foundations for architectural structures, etc.

[0024] To construct a laying layer using the method of the present invention, first, as shown in Figure 1, coarse aggregate 2 is laid to the required thickness on ground 1 (ground that has been excavated to a predetermined level in advance, if necessary), and then compacted with a roller or the like to form coarse aggregate layer a. Coarse aggregate 2 can be one or more of the coarse aggregates used in ordinary concrete, such as natural aggregate, crushed stone, recycled aggregate, and slag roadbed material. The size of the coarse aggregate is not particularly specified, but to ensure good filling of the paste p, the maximum size of the coarse aggregate is preferably 20 mm or more. On the other hand, there is no particular upper limit to the size of the coarse aggregate, but since aggregates for concrete generally have maximum sizes of 20 mm, 25 mm, or 40 mm, it is generally desirable for the maximum size to be 40 mm or less. Here, in the present invention, in accordance with JIS A1102 "Sieving Test Method for Aggregates," the maximum size of the coarse aggregate is defined as the nominal size of the smallest sieve among sieves through which 90% by mass or more of the coarse aggregate passes.

[0025] There are no particular restrictions on the thickness of the coarse aggregate layer a, and the thickness may vary depending on the configuration shown in Figures 2(A) and 2(B) and 3(A) and 3(B), which will be described later, but it is generally preferable to set the average thickness at around 30 to 50 mm. Here, the average thickness of the coarse aggregate layer a is the average value of the thickness measurements from the top end of the coarse aggregate layer a to the surface of the ground at nine or more points selected arbitrarily within the plot. The coarse aggregate layer a may be constructed as a single layer at once, or in multiple layers. In the case of multiple layers, it is preferable to loosen the compaction of the surface layer or to use coarse aggregate from which small particles have been removed by sieving, taking into consideration the filling ability of the paste p. It is preferable that battens are arranged on the side surfaces of the coarse aggregate layer a to level the upper surface of the coarse aggregate layer a and to prevent the paste p (particularly cement slurry) being poured from flowing out.

[0026] After the coarse aggregate layer a is formed as described above, a paste p (including paste in which part of the cement is replaced with ground granulated blast furnace slag) containing cement as a binder is poured on top of the coarse aggregate layer a. This paste p flows into and fills the gaps 3 between the coarse aggregate 2 (particles) that make up the coarse aggregate layer a, forming the paste-filled portion a. p In the present invention, the paste p is filled into the gaps 3 in at least the upper region of the coarse aggregate layer a to form the paste-filled portion a. p At the same time, the top surface of the coarse aggregate layer a is buried in the paste p. Then, after adjusting the level and flatness of the top surface of the paste p, which will serve as the foundation marking surface (finishing surface), the paste p is solidified into a hydrated hardened body. This results in the construction of the laying layer L, whose top surface is made of a hydrated hardened body and which will serve as the foundation marking surface.

[0027] The paste p using cement as a binder (including paste in which part of the cement is replaced with ground granulated blast furnace slag) used in the present invention is cement slurry or mortar (cement mortar). Furthermore, when the paste p is mortar, the fine aggregate can be one or more of those used in ordinary mortar, i.e., natural fine aggregate (land sand, river sand, sea sand, etc.), artificial fine aggregate (crushed sand, blast furnace slag fine aggregate, etc.), etc.

[0028] In this way, in the present invention, a coarse aggregate layer a is laid on the ground 1, and the required amount of paste p is poured on top of it in a predetermined manner. This paste p is then allowed to solidify, resulting in a laying layer L that serves as a substitute for basing concrete. Here, only the amount of paste p required for functionality (in this embodiment, the amount necessary for driving and holding nails for formwork construction) is poured. This reduces the amount of cement and paste poured, and the labor required for construction, compared to conventional basing concrete using ready-mixed concrete. Furthermore, with basing concrete, strict control of the ready-mixed concrete mix (including moisture control, etc.) is required to ensure the required workability and consistency, and the labor required for preparation is also required, resulting in increased costs. In contrast, the present invention does not use ready-mixed concrete, eliminating the corresponding costs. In other words, in the method of the present invention, in which coarse aggregate is first laid and then paste p is poured on top of it, the paste and coarse aggregate are already separated, so there is no need to consider the separation resistance of the coarse aggregate and paste during concrete pouring. For this reason, strict moisture control like with ready-mix concrete is not required, making it extremely easy to control and requiring fewer preparation steps, resulting in low costs. Furthermore, the surface of the laid layer (the outermost layer) is a paste surface that does not contain coarse aggregate, which has the advantage of making it easy to finish the surface. Furthermore, the paste p can be mixed on-site using a mortar mixer, and the pump used for construction can be smaller than that for concrete, so taking these points into account, the cost reduction effect is significant.

[0029] Paste filling section a p There are no special requirements for the thickness (depth) of the paste filling part a p When the thickness of the coarse aggregate layer a is less than the thickness of the coarse aggregate layer a, the surface layer of the coarse aggregate layer a is fixed with paste p to construct a stable laying layer. pThe average thickness of the paste filling part a is preferably 2 / 5 or more of the maximum dimension of the coarse aggregate. p The average thickness of the coarse aggregate layer a should be 10 mm or more. p (See FIG. 2.) Here, the paste filling portion a p The average thickness of the paste-filled part a at 9 or more points selected arbitrarily within the section p The average value of the thickness (depth) measurements is used.

[0030] Paste filling section a p The thickness of the paste p can be adjusted by controlling the filling degree of the paste p by adjusting or selecting one or more of the viscosity of the paste p, the size of the coarse aggregate 2, the degree of compaction of the coarse aggregate layer a, and the application of vibration when placing the paste. p To increase the thickness, it is effective to use a paste p with low viscosity, increase the size of the coarse aggregate, reduce the degree of compaction of the coarse aggregate layer a, and apply vibration when pouring the paste. Paste filling section a p The thickness of the paste filling part a can be controlled by the amount of paste p set based on the actual volume ratio of the coarse aggregate. For example, in a coarse aggregate layer a consisting of coarse aggregate with an actual volume ratio of 50%, p If the average thickness is set to 20 mm, the amount of paste p is prepared to a volume equivalent to a thickness of 10 mm, and is controlled by vibrating or smoothing with a trowel to finish the surface level.

[0031] In the present invention, in order to form the upper surface of the laid layer L to be constructed with a hydrated hardened paste p made of cement slurry or mortar, the paste p is poured so that the upper surface of the coarse aggregate layer a is buried in the paste p. The form in which the upper surface of the coarse aggregate layer a is buried in the paste p may be either (i) or (ii) below. (i) The upper surface of the paste p is the limit height at which the upper surface of the coarse aggregate layer a is buried, and the paste layer p is substantially above the coarse aggregate layer a. LIn other words, the coarse aggregate layer a is buried in the paste p so that its upper end level is substantially the same height as the finished surface of the paste p. (ii) A paste layer p is placed on top of the coarse aggregate layer a. L The top surface of the coarse aggregate layer a is covered with the paste layer p L In other words, the upper end level of the coarse aggregate layer a is buried in the paste p at a predetermined depth. In this form, the top layer of the laying layer L is buried in the paste p. L The hydrated hardened body layer (a layer consisting of only the hydrated hardened body) is formed by solidifying the above.

[0032] Here, when nailing into the laying layer L to fix the battens for constructing the formwork, a worker skilled enough to drive nails into ordinary concrete can drive nails without any problem in either of the above (i) or (ii). However, if the top layer of the laying layer L is made of the paste layer p of the above (ii), L The presence of a hydrated hardened body layer (a layer consisting only of hydrated hardened body) formed by the solidification of the concrete makes it easier to drive nails in and nailing is easier. In addition, the surface (top layer) of both (i) and (ii) is a paste surface, so it is easier to finish the surface than with a disposable concrete, but especially in the case of (ii), the paste layer p L Therefore, from these points of view, the above (ii) is preferable.

[0033] In the case of (ii) above, the paste layer p L There is no particular limit to the thickness of the paste layer p, but from the viewpoint of ease of nailing, securing nail holding power, and cost, L The average thickness of the paste layer p is preferably 10 mm or more and 30 mm or less. L The average thickness of the paste layer p at 9 or more randomly selected points in the section L The thickness of the paste layer (i.e., p L The average value of the measured thickness (thickness from the top surface of the layer a to the top end of the coarse aggregate layer a) is used. In addition, in order to ensure that the nails are driven into the upper surface of the laying layer to a depth of about 20 to 30 mm, in the case of (i) above, the paste filling part a p It is preferable that the average thickness of the paste filling portion a is 20 mm or more. p A thickness of about 30 mm is sufficient, so from a cost perspective, the paste filling part a p For the same reason, in the case of (ii) above, the average thickness of the paste layer p is preferably set to about 30 mm. L Average thickness of paste filling area a p It is preferable that the total average thickness of the above be 20 mm or more, while, in consideration of functionality and cost as described above, it is preferable that the upper limit be about 30 mm.

[0034] 2(a), (b) and 3(a), (b) show embodiments in which the paste p is poured in different ways, and are vertical cross-sectional views showing the state after the paste p has been poured onto the coarse aggregate layer a. Figure 2 shows that the paste p is filled in the entire thickness (depth) of the coarse aggregate layer a, and the paste-filled part a p On the other hand, Fig. 3 shows the case where the paste p is filled only in the upper region of the coarse aggregate layer a, and the paste filling part a p 2(a) and 3(a) show the case where a paste layer p is substantially formed on a coarse aggregate layer a. L In the case of (i) above, no layer is formed. Also, Figure 2 (a) and Figure 3 (a) show the case where a paste layer p is formed on top of a coarse aggregate layer a. L These show the above case (ii) in which

[0035] The configurations shown in Figures 2(A) and (B) and Figures 3(A) and (B) can be realized whether the paste p is a cement slurry or mortar. However, when the paste p is a cement slurry, the fluidity can be increased, making it easier to create the casting configuration shown in Figure 2. On the other hand, when the paste p is mortar, the fluidity is generally low, making it easier to create the casting configuration shown in Figure 3. However, depending on the water ratio and the degree of compaction of the coarse aggregate layer a, it is possible to create the casting configuration shown in Figure 3 even when the paste p is a cement slurry. When the paste p is mortar, it is best to create the casting configuration shown in Figure 3(A) without making it particularly highly fluid.

[0036] In the case of the pouring form of FIG. 3, in particular, the paste filling portion a p Or paste filling part a p +Paste layer p L The thickness of the concrete filling section a is required for its function (in this embodiment, the thickness required for nailing), so the amount of cement and paste used can be reduced accordingly. Among these, the casting form shown in Figure 3(A) can reduce the amount of cement and paste the most. In addition, in the case of the casting form shown in Figure 3, as mentioned above, the paste filling section a p That is, the required thickness can be adjusted by controlling the degree of filling of the paste p by adjusting or selecting one or more of the viscosity of the paste p, the size of the coarse aggregate, the degree of compaction of the coarse aggregate layer a, and the application of vibration when pouring the paste.

[0037] Next, the configuration of the laying layer (laying layer constructed on the ground) of the present invention will be described. The laying layer L of the present invention is a laying layer constructed on the ground, the upper surface of which is made of a hydrated hardened material, and is composed of a coarse aggregate layer A constructed by spreading coarse aggregate on the ground 1, and a hydrated hardened material B, which uses cement as a binder and is filled in at least a part of the coarse aggregate layer A. This hydrated hardened material B is filled in the voids in at least the upper region of the coarse aggregate layer A, forming a hydrated hardened material filled part A. pThe hydrated hardened body B is a solidified paste p using cement as a binder, and is made of cement or mortar (cement mortar), but part of the cement may be replaced with ground granulated blast furnace slag.

[0038] The form in which the upper surface of the coarse aggregate layer A is embedded in the hydrated hardened body B may be either (1) or (2) below. Here, the following (1) corresponds to the form (i) of the method of the present invention described above, and the following (2) corresponds to the form (ii) of the method of the present invention described above. (1) The upper surface of the hydrated hardened material B is the maximum height at which the upper surface of the coarse aggregate layer A is buried, and the hydrated hardened material layer B is substantially above the coarse aggregate layer A. L In other words, the coarse aggregate layer A is buried in the hydrated hardened material B so that its top level is approximately the same as the finished surface of the hydrated hardened material B. (2) Hydrated hardened material layer B on top of coarse aggregate layer A L The top surface of the coarse aggregate layer A is covered with the hydrated hardened material layer B. L In other words, the upper end level of the coarse aggregate layer A is buried in the hydrated hardened material B to a certain depth, and the hydrated hardened material layer B is on top of the coarse aggregate layer A. L (A layer consisting only of the hydrated hardened body) is formed. Of these, the above (2) is more preferable for the same reasons as those for the method of the present invention described above.

[0039] In the embodiments of Fig. 2(a), (b), Fig. 3(a), (b), for example, the laying layer L is obtained by forming a coarse aggregate layer a and then pouring paste p onto the coarse aggregate layer a, which solidifies to become a hydrated hardened body B. Therefore, the coarse aggregate layer a, paste p, and paste filling portion a in Fig. 2(a), (b), Fig. 3(a), (b) p , paste layer p L As a result, the coarse aggregate layer A of the laying layer L, the hydrated hardened body B, and the hydrated hardened body filling part A p , hydrated hardened body layer B L are constructed (formed) respectively. That is, the laying layer L obtained in the embodiment of FIG. 2 is a hydrated hardened material filled portion A in which the hydrated hardened material B is filled in the entire thickness direction of the coarse aggregate layer A. p On the other hand, in the embodiment of FIG. 3, the laying layer L is formed by filling the hydrated hardened material B only in the upper region of the coarse aggregate layer A, forming a hydrated hardened material filling portion A. p 2(a) and 3(a), the laying layer L is substantially composed of a hydrated hardened material layer B on a coarse aggregate layer A. L In addition, the laying layer L obtained in the embodiment of Fig. 2(a) and Fig. 3(a) has a hydrated hardened material layer B on a coarse aggregate layer A. L This results in the above form (2).

[0040] Here, the maximum size of the coarse aggregate constituting the coarse aggregate layer A is preferably 20 mm or more. The average thickness of the coarse aggregate layer A is preferably about 30 to 50 mm. p If the thickness of the coarse aggregate layer A is less than the thickness of the coarse aggregate layer A, the hydrated hardened material filling part A p The average thickness (depth) of the hydrated hardened body layer B is preferably 2 / 5 or more of the maximum dimension of the coarse aggregate. L The average thickness of the hydrated hardened body filling part A is preferably 10 mm or more and 30 mm or less. p The average thickness (depth) of the hydrated hardened body layer B is preferably 20 mm or more, and in consideration of cost, the upper limit is preferably about 30 mm. L Average thickness of hydrated hardened body filling part A p The total average thickness (depth) of the layers is preferably 20 mm or more, while taking cost into consideration, the upper limit is preferably set at about 30 mm. The reasons for this are the same as those for the method of the present invention described above.

[0041] Here, the average thickness of the coarse aggregate layer A is the average value of the thickness measurements from the top of the coarse aggregate layer A to the surface of the ground at nine or more points selected arbitrarily within the plot. p The average thickness of the hydrated hardened body filling part A at 9 or more points selected arbitrarily within the section pThe average value of the thickness (depth) of the hydrated hardened body layer B is used. L The average thickness of the hydrated hardened body layer B at 9 or more points selected arbitrarily within the area L Thickness of the hydrated hardened body layer B L The average value of the measured thickness (from the top surface of the aggregate layer to the top end of the coarse aggregate layer A) is used.

[0042] 4 is a longitudinal cross-sectional view showing a schematic diagram of one embodiment of the constructed laying layer L. In this embodiment, the laying layer L is formed by filling the hydrated hardened material B only in the upper region of the coarse aggregate layer A, forming a hydrated hardened material filling section A. p The hydrated hardened material layer B is placed on top of the coarse aggregate layer A so that the top surface of the coarse aggregate layer A is buried in the hydrated hardened material B. L This laying layer L is a laying layer obtained when the paste p is poured in the form of FIG. 3(A), and the hydrated hardened body filling part A p and hydrated hardened body layer B L are the paste filling part a in Figure 3(a), respectively. p and paste layer p L It is composed of the following. In FIG. 4, in order to fix the battens 4 for constructing the formwork on the upper surface 6 of the laying layer L, the hydrated hardened body layer B L and hydrated hardened body filling section A p 1 shows a state in which a nail 5 has been driven into the hole.

[0043] In this embodiment, the upper surface 6 of the laying layer L can be marked out the day after construction, and the nails 5 for fixing the battens 4 for fastening the formwork can be driven in the day after that. L and hydrated hardened body filling section A pThe nail 5 penetrates easily into the concrete and is held in place. Furthermore, as will be described later, if part of the cement is replaced with ground granulated blast furnace slag at a high replacement rate, the strength development of the hydrated hardened material B is delayed, and the difference in strength with the coarse aggregate increases. Therefore, as shown in Figure 4, the driven nail 5 penetrates the weaker hydrated hardened material B by filling in the gaps between the coarse aggregates, deforming (bending) it, and is held in that state. Because the nail 5 is held in this deformed (bent) state, the frictional resistance when the nail is pulled out increases, and the vertical pull-out force of the nail 5 immediately after driving it can reach 40 kgf or more.

[0044] Other preferred application conditions and construction layers of the present invention will be explained below with reference to test examples. The explanation will be mainly based on an example in which cement is used as a binder, but as will be described later, in the present invention, part of the cement may be replaced with ground granulated blast furnace slag as a binder. <Pouring paste p> When pouring the paste p, the amount to be poured is determined taking into account the void ratio of the coarse aggregate, etc., so that the paste p will be in the desired poured state according to the form shown in Figures 2(a) and (b) or Figures 3(a) and (b). For example, if cement slurry is used as paste p and poured as shown in Figure 2 (a) and (b), the paste will fill almost all of the gaps in the coarse aggregate layer a during normal times (excluding severe winter and hot summer months). Light vibration (from the formwork or the top surface of the coarse aggregate layer a) will ensure more reliable filling. The larger the maximum dimensions of the coarse aggregate, the better the filling tends to be.

[0045] The weight ratio of binder to water (binder:water) of the paste p is preferably about 1:0.5 to 0.6. If the amount of water is greater than this, bleeding will increase and the binder may settle over time. If the amount of water is less than the above, the fluidity will be low and the hardening will be rapid, which may cause problems during construction. Note that the amount of water may be adjusted using chemical admixtures, etc., as described below. When the paste (p) is mortar, the weight ratio of binder to fine aggregate (binder:fine aggregate) is preferably about 1:3-5. If the amount of fine aggregate is too small relative to the amount of binder, the mortar will not have the desired viscosity, and there is a risk that it will flow into the gaps between the coarse aggregates more than expected, lowering the top surface level. On the other hand, if the amount of fine aggregate is too large relative to the amount of binder, the fluidity will be low and it will not be able to fill the gaps between the coarse aggregates well.

[0046] If the paste is cement slurry When a cement slurry is used for the paste p, the cement slurry has a high reproducibility of fresh properties even when mixed on-site, and is easier to manage than concrete. As shown in Figure 2(A), if the top surface of the paste (cement slurry) is set to the maximum height necessary to bury the coarse aggregate layer (a), the cement surface will harden quickly and become stronger, which may require skill in nailing. To confirm this, the following test was conducted. This test is referred to as "Test Example 1." In this test, cement slurry was used as the paste p, and the test specimen (laying layer) was prepared as follows: In this test, trial mixing was performed using a mortar mixer and a hand mixer, and it was confirmed that equivalent fresh properties could be obtained with each, but the mixing means is not limited to these.

[0047] Coarse aggregate (maximum dimension 25 mm) was laid in a formwork approximately 300 mm x 300 mm in planar dimensions (length and width) and 80 mm in height, and then compacted by vibration to create a coarse aggregate layer a with an average thickness of 50 mm. A cement slurry with a cement-to-water weight ratio (cement:water) of 1:0.5 was poured into this coarse aggregate layer a. Since the volume fraction of the coarse aggregate was approximately 50%, the cement slurry was poured in an amount equivalent to 25 mm (50% of the thickness of coarse aggregate layer a) (2.25 L) so that it filled all of the voids 3 in the coarse aggregate layer a, as shown in Figure 2(a). Ordinary Portland cement was used, and the cement slurry was mixed using a hand mixer. The mixing time was 30 seconds. For reference, the fresh properties of the cement slurry were measured simply. This method differs from the test methods specified in JIS and other standards, and therefore serves only as a reference value for relative comparison. The equipment used was a soil testing cone with a base diameter of 90 mm and a height of 75 mm. The flow was measured on a surface plate and its shape was observed. The flow was measured perpendicular to the maximum diameter and spread concentrically at 187 mm x 187 mm.

[0048] During the cement slurry pouring work, the entire amount of cement slurry was poured from above into the center of coarse aggregate layer A, and then the formwork was lightly tapped around the periphery to spread it over the entire surface, filling it to the extent that the coarse aggregate did not protrude from the surface of the cement slurry. The curing period was set at two days, assuming the day after construction, and the cement slurry was left to harden, obtaining a test specimen (laying layer) consisting of coarse aggregate layer A and hydrated hardened body B. Two days after the cement slurry was poured and the test specimens were constructed, workers conducted a nail-driving test from the top of the specimen. First, a general worker with no experience driving nails into mortar concrete drove a #12 nail into the specimen until the tip penetrated 20 mm from the top. However, he had difficulty driving the nail, and the impact during the process caused the surface layer to peel off in a shallow, concentric circle approximately 30–40 mm in diameter and scatter. When the driven nail was statically pulled vertically, the nail pull-out strength was less than 30 kgf. Meanwhile, a worker with experience driving nails into mortar concrete separately drove the nails under the same conditions without any problems, and the holding strength was also satisfactory. Therefore, to make nailing easier regardless of worker skill, a similar test was conducted with the cement-to-water weight ratio (cement:water) of the cement slurry reduced to 1:0.6 to reduce the initial strength. The general worker was then able to drive the nails without any problems. After the test, the back of the test specimen was observed and it was confirmed that the hydrated solidified material B had filled almost all of the voids in the coarse aggregate layer A, as shown in Figure 2(a).

[0049] As will be described later, in order to make it easier to drive nails and ensure the holding power of the driven nails, it is effective to delay the development of the initial strength of the hydrated hardened body by replacing part of the cement with ground granulated blast furnace slag. Furthermore, a paste layer p is placed on top of the coarse aggregate layer a (coarse aggregate layer A). L (Hydrated hardened body layer B L ) is effective. Here, the following tests were carried out for the cases where the cement in the above-mentioned cement slurry was replaced with ground granulated blast furnace slag at replacement rates of 50% and 70% (the unit of replacement rate of ground granulated blast furnace slag is "weight %"; the same applies below). The flow of the cement slurry was 199mm x 199mm and 180mm x 180mm, respectively. Here, the paste filling section a was filled to form the shape shown in Figure 3(a). p The average thickness of the paste layer is 10 mm. LThe average thickness was 15 mm, and a cement slurry equivalent to a thickness of 20 mm was poured into the coarse aggregate layer a. The poured cement slurry filled naturally when lightly vibrated, and the filling properties were extremely good. After hardening, both were easy to nail, and although the pull-out strength could not be measured, they could not be pulled out statically in the vertical direction, so they were pulled out with a crowbar. Furthermore, a field application test was carried out on a cement slurry with a replacement rate of 50% for granulated blast furnace slag. Here, slag roadbed material was used for coarse aggregate 2, but because it was compacted at a high density, the paste filling area a p The average thickness of the paste layer p is 5 mm or less. L The average thickness was set at 20 mm. The cement slurry application could be pumped using a drainage pump (submersible pump), eliminating the need for a pump truck, which resulted in significant cost savings. Nailing was easy, and the average nail pull-out strength was over 70 kgf.

[0050] If the paste is mortar When mortar was used as the paste p, the following test was conducted to confirm the filling ability of the mortar into the coarse aggregate layer a and the ease of nailing. This test is referred to as "Test Example 2." The mortar had a cement to fine aggregate weight ratio (cement:fine aggregate) of 1:3, and land sand was used as the fine aggregate. The cement to water weight ratio (cement:water) was 1:0.5, and the filling ability into the coarse aggregate layer a was verified. Again, as in Test Example 1, the flow and slump were measured and the shape was observed to easily grasp the fresh properties of the mortar. The formwork and coarse aggregate used to obtain the test specimen were the same as those used in Test Example 1, and a coarse aggregate layer a was prepared under the same conditions as in Test Example 1. The mortar prepared as described above was poured into this coarse aggregate layer a.

[0051] The mortar is a paste layer p of average thickness 20 mm in the form of Figure 3 (a). L , paste-filled part a with an average thickness of 20 mm pAssuming that a thickness of 30mm would be formed, a volume (2.7L) was prepared. Test mixing of the mortar was carried out using a mortar mixer and a hand mixer, and as there was no difference in the fresh properties between the two and the reproducibility was high, the hand mixer was used. The mixing time was 30 seconds for mixing the cement and fine aggregate, then water was added and mixed for 60 seconds. The flow of the mortar immediately after mixing was 92mm / 92mm and the slump was 8mm. The poured mortar did not naturally fill into the coarse aggregate layer a, but it was able to be leveled without any problems with a metal trowel at a position 70mm high in the formwork, i.e., 20mm above the top edge of the coarse aggregate layer a. As a result, a paste layer p with an average thickness of 20mm was formed as targeted. L and paste-filled area a with an average thickness of 20 mm p As a result, the paste filling part a p In this test, the paste p and coarse aggregate became one, and a layer equivalent to ordinary concrete was obtained. The mortar's slump and flow did not appear to be fluid numerically, but it was hard enough to be easily leveled with a trowel. The curing period was set at two days, simulating the day after construction, as in Test Example 1, and the mortar was left to harden, obtaining a test specimen (laying layer) consisting of a coarse aggregate layer A and a hydrated hardened body B.

[0052] As in Test Example 1, two days after the mortar was poured and the test specimen was constructed, a test was conducted in which a general worker drove a #12 nail into the top of the specimen. The surface of the specimen had hardened and appeared hard, but nails could be driven into the specimen (mortar layer) without any problems. In addition, a pull-out test was conducted to pull out the nails, and the pull-out strength was approximately 45 kgf. Given the mortar composition (50% water-cement ratio), the constructed layer is considered to have nail holding strength comparable to that of ordinary concrete. After the test, the specimen was inspected and it was found that the coarse aggregate in the upper region of the coarse aggregate layer A was fixed with hydrated hardened material B, and the entire surface was filled with hydrated hardened material A. pWhen the weight ratio of cement to water in the mortar (cement:water) was 1:0.6, the flow was 114mm / 115mm, and by applying vibration, it was possible to fill the mortar naturally, just like in the case of the cement slurry mentioned above. However, if the amount of water exceeded this, bleeding increased and the fine aggregate separated. Furthermore, in order to reduce the use of natural aggregates from an environmental perspective, blast furnace slag fine aggregate may be used for at least a portion of the fine aggregate. In a separate concrete mix test, when 50% or 100% of the natural aggregate weight was replaced with blast furnace slag fine aggregate, the strength changed depending on the replacement rate of blast furnace slag fine aggregate, and at a replacement rate of 50%, the strength was equal to or greater than that of ordinary concrete. Furthermore, there was a tendency for the strength to decrease when the replacement rate exceeded 50%, but even at a replacement rate of 100%, the strength was equal to that of concrete made with blast furnace cement type B.

[0053] <Replacing cement with ground granulated blast furnace slag> As mentioned above, when constructing foundations for building structures, the top surface of the laying layer (conventionally constructed with basal concrete) is generally marked out the day after construction, and nailing is performed on the top surface of the laying layer for formwork construction the day after. Therefore, since the laying layer solidifies and achieves a flat surface the day after construction, and only requires the strength to be strong enough to allow nailing and hold the nails the day after, it is not necessary to increase the strength of the top surface of the laying layer (hydrated hardened body) at this stage. On the other hand, it is known that replacing part of the cement in concrete with ground granulated blast furnace slag delays the development of early strength. For this reason, in the concrete engineering field, it has been considered practical to limit the substitution rate of ground granulated blast furnace slag to 50% or less to prevent the delay in early strength development. However, in the case of the laying layer constructed in the present invention, a lower early strength of the hydrated hardened body facilitates nailing, and since the hydrated hardened body only needs to have enough holding power to prevent nails from easily slipping out, a lower early strength can actually be advantageous for foundation construction.

[0054] Therefore, in this invention, a portion of the cement is replaced with ground granulated blast furnace slag at a high substitution rate, which delays the development of early strength and improves nailing workability, while also providing the necessary and sufficient nail holding power (nail pull-out strength) and preventing problems with marking and formwork assembly. The blending range of ground granulated blast furnace slag was investigated to determine the blending range. As a result, it was found that approximately 50 to 70% of the cement weight should be replaced with ground granulated blast furnace slag. Even with this blend, the development of early strength is delayed, as sufficient strength is obtained over the long term, and the safety of the structure in service is not compromised. Furthermore, the paste P produced by this blend is soft and viscous, but not sticky. Therefore, the paste does not stick to the trowel during leveling (surface finishing), improving workability. For this reason, in the present invention, it is preferable to replace a portion of the cement that constitutes the paste p (and the hydrated hardened body B) with ground granulated blast furnace slag at a high replacement rate, specifically, to replace approximately 50 to 70% of the cement weight with ground granulated blast furnace slag.

[0055] In this way, in the present invention, by replacing part of the cement with ground granulated blast furnace slag at a high substitution rate, it is possible to effectively utilize the by-products of the steel manufacturing process and reduce CO2 emissions. For example, in the case of cement slurry, CO2 emissions can be reduced by 40% or more. Furthermore, when a portion of the cement is replaced with ground granulated blast furnace slag at a high replacement rate, delaying the development of strength in hydrated body B, the difference in strength between hydrated body B and the coarse aggregate increases, causing the driven nail to deform. This, in turn, results in a greater frictional resistance, improving the nail's pull-out strength. In other words, when a portion of the cement is replaced with ground granulated blast furnace slag at a high replacement rate, the difference in strength between hydrated body B and the coarse aggregate is greater than the difference in strength between hydrated body B and the coarse aggregate in the early stages of pouring ready-mixed concrete. Therefore, nails driven into the top of the laying layer to construct the formwork penetrate between the coarse aggregate, deforming (bending) the weaker hydrated body B, and are held in that state, as shown in Figure 4. This bending of the nail increases frictional resistance during nail withdrawal, enabling the nail to achieve a vertical pull-out force of over 40 kgf immediately after driving.

[0056] When part of the cement constituting the paste p (and the hydrated hardened body B) was replaced with ground granulated blast furnace slag, the following test was conducted to confirm the filling ability of the paste p into the coarse aggregate layer a and the workability of nailing into the laying layer. This test is referred to as "Test Example 3." In this test, part of the cement in the mortar (paste p) of Test Example 2 was replaced with ground granulated blast furnace slag. The replacement ratio of ground granulated blast furnace slag was set to two levels: 50% and 70% by cement weight. The mortar was prepared by premixing cement and ground granulated blast furnace slag, and the kneading process was the same as in Test Example 2. When tested using the same tests as the previous tests, both replacement ratios of 50% and 70% showed no spreading at 90mm / 90mm, and a slump of 9mm. While the numerical values ​​were not significantly different from those of Test Example 2, the softness and viscosity prevented flow and caused the mortar to swell and collapse at the midpoint of its height. While the replacement ratios of 50% and 70% showed lower flow and slump values, the mortar was softer and easier to work with than Test Example 2, and the resistance to troweling was lower. Furthermore, the higher the replacement ratio, the better the workability.

[0057] The day after the mortar was poured and the test specimen was constructed, the same nail driving and pull-out tests as in Test Example 2 were carried out. Due to the effect of delayed initial strength development, nail driving was easier than in Test Example 2. The #12 nail that was driven in penetrated the surface hydrated hardened layer B without damaging the surrounding area. L The nails penetrated easily and were held in place, and damage to the surrounding area due to nailing was reduced, so the pull-out strength exceeded 40 kgf in all cases. However, with a replacement rate of 50%, the pull-out strength was 65 kgf, but with a replacement rate of 70%, it was only 42 kgf, so the 50% replacement rate provided better results in terms of ease of nailing and nail holding power. After the test, the back side was checked and the hydrated hardened body filling part A was found to be more p The filling ability was relatively good in the outer periphery where the area was thick and not pressed in with the trowel, and it was possible to improve the filling ability by simply pressing in with the trowel. The filling ability was better at a replacement rate of 70%.

[0058] When the replacement rate of ground granulated blast furnace slag was set to 50% and 70%, as above, and the weight ratio of cement to water (cement:water) was set to 1:0.6, the flow became 109mm x 105mm. p The average thickness of the paste layer is 10 mm. L When mortar equivalent to a thickness of 20 mm was poured into the coarse aggregate layer a with an average thickness of 15 mm, the filling property was extremely good, and there was no settlement or bleeding during hardening, resulting in a good condition. Furthermore, nailing after hardening was easy, and although the pull-out strength could not be measured, it could not be pulled out statically in the vertical direction, so it was pulled out with a crowbar. Furthermore, as in Test Example 1, a field construction test was conducted using mortar with a replacement rate of 50% ground granulated blast furnace slag. It was possible to pump it with a mortar pump Φ40 mm, eliminating the need for a pump truck. Although the pull-out strength could not be measured, workers evaluated that there were no problems with nailing or holding power.

[0059] <Use of blast furnace slag fine aggregate> In the present invention, from the viewpoint of environmental protection by reducing the use of natural aggregates, blast furnace slag fine aggregate may be used as part or all of the fine aggregate of the mortar. Therefore, blast furnace slag fine aggregate may be used in place of part or all of the natural fine aggregate. Blast furnace slag fine aggregate has a sharp shape because it is granulated blast furnace slag. However, when examining the retention state of the driven nails from the verification results of the nail pull-out section of Test Example 3, it was found that by using blast furnace slag fine aggregate, which has a sharp shape, for part or all of the fine aggregate, the friction between the hardened mortar and the nails becomes greater than when natural fine aggregate is used, and it is thought that the nail retention force can be increased. Therefore, in addition to the same verification as the other test examples, the following test was conducted on the use of blast furnace slag fine aggregate (replacing natural fine aggregate (land sand) with blast furnace slag fine aggregate) to verify the effect of improving nail pull-out strength based on the above assumption. This test is called "Test Example 4." In Test Example 3, favorable results were obtained with a replacement rate of 50% for ground granulated blast furnace slag, so for this specification, natural fine aggregate was replaced with fine blast furnace slag aggregate. Two replacement rates were set: 50% and 100%.

[0060] Tests similar to those described above yielded the following results. At both 50% and 100% blast furnace slag fine aggregate replacement rates, the flow was 90 mm / 90 mm and did not spread. However, at a 50% replacement rate, the mix was softer than in Test Example 3, with significant crushing in the middle section and a slump of 16 mm. When poured into the coarse aggregate layer (a), the mix was soft and easy to press, and trowel-leveling was also easy. At a 100% replacement rate, the slump was 7 mm, similar to Test Example 3 but less viscous than at a 50% replacement rate. Although bleeding occurred approximately 10 minutes after pouring, it was not significant, making it easier to finish the surface with a trowel. Furthermore, leaving the mix to stand for several minutes after mixing and then remixing significantly improved the mix, improving workability. Therefore, at a 100% replacement rate, adjusting the mixing method to control workability is preferable. The nails were easy to hammer in, but the nail pull-out strength was 65 kgf at a replacement rate of 50%, and 70 kgf at a replacement rate of 100%, but the nails could not be pulled out. Therefore, the test was stopped and the nails were pulled out with a crowbar.

[0061] After the test, the back of the specimen was checked and it was found that a larger amount of coarse aggregate was attached than in Test Example 3 (i.e., the hydrated hardened body filling part A). p The thickness of the mortar was thicker, and the filling properties of the mortar were generally good. In a separate mix test of concrete in which 50% of the cement weight was replaced with ground granulated blast furnace slag, the compressive strength was equivalent when 50% and 100% of the natural fine aggregate weight was replaced with blast furnace slag fine aggregate. In contrast, the nail pull-out strength results obtained in Test Example 4 showed a different trend from the results of the above concrete mix test. That is, under conditions of low compressive strength, at least two days after construction, the nail pull-out strength was shown to increase with a higher replacement rate of blast furnace slag fine aggregate and greater friction. Therefore, given the desired fresh properties and strength, the more blast furnace slag fine aggregate used, the better.

[0062] In addition, the replacement rate of fine blast furnace slag aggregate was set to 50%, and the cement-to-water weight ratio (cement:water) was changed from 1:0.5 to 1:0.6. Comparisons were made between replacement rates of 50% and 70% ground granulated blast furnace slag. The resulting flow dimensions were larger (102mm x 111mm and 112mm x 109mm, respectively), but were generally equivalent. There was no significant difference in packing ability; although spontaneous packing did not occur, light leveling with a trowel allowed for smooth filling. Furthermore, similar to Test Example 3, a field application test was conducted using mortar with a 50% replacement rate of ground granulated blast furnace slag. Pumpability was better than in Test Example 3, and viscosity during pouring was also excellent. Furthermore, the mortar showed the least adhesion to the trowel and mortar during leveling, resulting in excellent workability. Although pull-out strength could not be measured, workers evaluated both nailing and holding strength as satisfactory. From the above results, when blast furnace slag fine aggregate is used as the fine aggregate of mortar in the present invention, it is preferable that 50 mass % or more of the fine aggregate is blast furnace slag fine aggregate.

[0063] <Addition of specific chemical admixtures> To improve the fresh properties and workability of the paste p used in the present invention, a chemical admixture (AE water-reducing agent) containing a lignin sulfonate compound and a polycarboxylic acid ether as ingredients can be added in an amount of 0.5% to 1% of the binder weight. In this case, it is desirable to reduce the amount of water by about 10% and set the weight ratio of the binder to the total weight of water and chemical admixture (binder:water + chemical admixture) to about 1:0.45 to 0.54. Based on the results of Test Examples 3 and 4, the natural fine aggregate was replaced with blast furnace slag fine aggregate at a replacement rate of 70% and the above-mentioned chemical admixtures were added to the mortar. The following test was conducted to verify the fresh properties, workability, and nail pull-out strength of the mortar. This test is designated "Test Example 5."

[0064] In Test Example 3, a comparison of 50% and 70% blast furnace slag substitution rates revealed comparable fresh properties and workability. While nail pull-out strength was higher at the 50% substitution rate, even at the 70% substitution rate, the mortar still achieved higher strength than conventional mortar. Based on these results, in order to further reduce CO2 emissions, we increased the substitution rate to 70% and replaced all natural fine aggregate with blast furnace slag fine aggregate to improve nail pull-out strength. Furthermore, to improve fresh properties and workability, we added an air-entraining water-reducing agent (AE water-reducing agent primarily composed of a complex of lignosulfonic acid compounds and polycarboxylic acid ethers) as a chemical admixture. This chemical admixture was added at 1% of the binder weight, reducing the combined weight ratio of water and chemical admixture to binder weight by 0.5 to 10%. That is, the weight ratio of the binder to the total of water and chemical admixtures (binder:water+chemical admixtures) was set to 1:0.45.

[0065] As in Test Example 4, the replacement rates of blast furnace slag fine aggregate were set to 50% and 100%, and the same tests as those in the previous Test Examples were conducted. The following results were obtained. At a replacement rate of 50% blast furnace slag fine aggregate, the flow was 97mm / 95mm and the slump was 28mm, making it softer than Test Example 4. At a replacement rate of 100%, the mortar viscosity was low and it tended to break apart (a phenomenon in which the mortar separates and the mortar layer breaks apart) in Test Example 4 was significantly improved, with a flow of 154mm / 156mm and a slump of 46mm. The shape of the test specimen was also good, with the outer periphery exhibiting a pancake shape that maintained a circular arc in the height direction, and viscosity was maintained, preventing breakup. The ability of the mortar to fill the coarse aggregate layer a was also superior when the replacement rate of blast furnace slag fine aggregate was 100%, and when producing the test specimens, the mortar filled the coarse aggregate layer a naturally within the formwork, and it was possible to fill it to the specified height without vibrating or compressing it. The nailing, which took place two days after the mortar was poured and the test specimen was constructed, was extremely easy, but the nails had such a high pull-out strength that the test was stopped at 76 kgf and the nails were pulled out with a crowbar. The filling condition of hydrated hardened material B on the back of the test specimen was also extremely good.

[0066] <Addition of ground granulated blast furnace slag as an admixture> The paste (mortar) consists of blast furnace slag fine aggregate, and 50% to 70% of the cement weight is replaced with ground granulated blast furnace slag. In addition, to improve viscosity and further reduce CO2 emissions, 20±5% of the binder weight of ground granulated blast furnace slag can be added as an admixture. In this case, the amount of ground granulated blast furnace slag (admixture) can be adjusted within the range of 20±5% depending on the temperature and moisture content. In Test Example 4, when the replacement rate of blast furnace slag fine aggregate was 100%, the viscosity of the mortar was lower than when the replacement rate was 50%. Therefore, to improve viscosity and further reduce CO2 emissions, ground granulated blast furnace slag was added as an admixture and used for testing. That is, ground granulated blast furnace slag was added as an admixture to a mortar with a replacement rate of 100% blast furnace slag fine aggregate, and the following test was conducted to confirm the effect of adding ground granulated blast furnace slag as an admixture to replace the fine aggregate. This test is referred to as "Test Example 6."

[0067] In Test Example 4, 50% of the cement weight was replaced with ground granulated blast furnace slag as the binder, and all natural fine aggregate was replaced with ground granulated blast furnace slag. 20% of the binder weight was added as a fine aggregate substitute admixture. This resulted in a fine aggregate to binder weight ratio of 3.2. In other words, this mortar had 50% of the cement weight replaced with ground granulated blast furnace slag as the binder, and the fine aggregate to binder weight ratio was 3.2. Approximately 93-94% of the natural fine aggregate weight was replaced with ground granulated blast furnace slag, and approximately 7-6% was replaced with ground granulated blast furnace slag. Furthermore, as a chemical admixture, an air-entraining water-reducing agent containing a lignosulfonic acid compound and a polycarboxylic acid ether as ingredients (an air-entraining water-reducing agent whose main component is a complex of a lignosulfonic acid compound and a polycarboxylic acid ether) was added at 0.5% of the binder weight.

[0068] When the same tests as those for the above test examples were carried out, the following results were obtained. The flow did not change significantly, at 91mm / 91mm compared to 90mm / 90mm in test example 4, but the slump improved from 7mm to 17mm, a value equivalent to the 50% replacement rate of fine blast furnace slag aggregate in test example 4. The filling of the mortar into the coarse aggregate layer a was better than in test example 4, and there was little adhesion of mortar to the trowel, making construction easier. Two days after the mortar was poured and the test specimen was constructed, nail driving and pull-out tests were carried out in the same manner as in Test Examples 2 and 3. The nail driving was very easy, similar to Test Example 5. The nail pull-out strength was also high, and the test was stopped at about 80 kgf, and the nail was pulled out with a crowbar.

[0069] In the above test examples, the nail pull-out strength was 40 kgf or more when a paste layer p of a certain thickness (average thickness 20 mm) was formed on top of the coarse aggregate layer a (coarse aggregate layer A). L (Hydrated hardened body layer B L In particular, by replacing part of the cement with ground granulated blast furnace slag at a high substitution rate and delaying the development of strength, the workability and nailing properties of the paste p were improved, and the pull-out strength of the nails was particularly high. In other words, in this case, the driven #12 nail penetrated the low-strength hydrated hardened layer B of the surface without destroying the surrounding area. L As a result, a pull-out strength of much more than 40 kgf was obtained. After the test, the specimen was dismantled and the penetration pattern of the nails was examined. As shown in Figure 4, the nails penetrated into the hydrated hardening material filled part A without damaging the surrounding area. p The nail penetrated while deforming, filling in the gaps between the coarse aggregates. As mentioned previously, this penetration pattern is thought to be due to the large difference in strength between the hydrated hardened body B, which has delayed strength development, and the coarse aggregate. Furthermore, the friction marks observed at the bend in the penetration path of nail 5 suggest that this type of penetration pattern increased the friction resistance during withdrawal, thereby increasing the pull-out strength. Furthermore, it was confirmed that the pull-out strength of the nails can be further increased by using blast furnace slag fine aggregate as the fine aggregate and increasing its usage ratio.

[0070] The amount of paste p to be poured (paste layer p) is determined according to the required nail pull-out strength. L Average thickness of paste filling area a p The paste composition in each test example is a basic composition, and may differ from the values ​​disclosed here due to adjustments according to the season and weather, but it is sufficient if it is within the range of the present invention described above. In order to improve the ease of nailing, the strength of the hydrated hardened body B can be reduced by using a lean cement mix, but low strength is only necessary when driving the nails, and high strength is desirable in the long term, so it is best to use ground granulated blast furnace slag.

[0071] In view of the above, a particularly preferred embodiment of the construction method of the present invention is a method in which the paste (p) is mortar, in which 50% to 70% of the cement weight is replaced with ground granulated blast furnace slag as a binder, and 50% by weight or more of the fine aggregate is blast furnace slag fine aggregate, and the cast paste (p) forms a paste layer (p) having an average thickness of 10 mm to 30 mm on the coarse aggregate layer (a). L The paste filling part a is formed only in the upper region of the coarse aggregate layer a. p is formed, and the paste filling portion a p The method for constructing a laying layer of hydrated hardened material B, the upper surface of which is made of hydrated hardened material, has an average thickness of at least 2 / 5 of the maximum dimension of the coarse aggregate. Therefore, a particularly preferred installation form of the laying layer of the present invention is a laying layer of hydrated hardened material B, the upper surface of which is made of mortar, in which 50% to 70% of the cement weight is replaced with ground granulated blast furnace slag as a binder, and 50% by weight or more of the fine aggregate is made of blast furnace slag fine aggregate, and the average thickness of the laying layer of hydrated hardened material B is 10 mm to 30 mm on top of the coarse aggregate layer A. L The hydrated hardened material filling part A is formed only in the upper region of the coarse aggregate layer A. p is formed, and the hydrated hardened body filling part A p The average thickness of the layer is at least 2 / 5 of the maximum dimension of the coarse aggregate, and the upper surface is made of a hydrated hardened body. The technical significance and limitations of each of these configurations have been described above. [Explanation of symbols]

[0072] 1 site 2 Coarse aggregate 3. Gap 4 oak trees 5 nails 6 above a Coarse aggregate layer a p ペースト filling department p ペースト p L ペーストlayer A Coarse aggregate layer A p Water and hardened body filling B Water and hardened body B L Water and hardened layer L laying layer

Claims

1. A method for constructing a laying layer on the ground, the upper surface of which is made of a hydrated hardened body, comprising: Coarse aggregate is laid on the ground to form a coarse aggregate layer (a), and then a paste (p) containing cement as a binder (including a paste in which part of the cement is replaced with ground granulated blast furnace slag) is poured on top of the coarse aggregate layer (a), filling the voids in at least the upper region of the coarse aggregate layer (a) with the paste (p) to form a paste-filled portion (a ｐ ) and burying the upper surface of the coarse aggregate layer (a) in paste (p), and solidifying the paste (p) in this state to form a hydrated hardened body.

2. Paste filling portion (a) of coarse aggregate layer (a) ｐ 2. A method for constructing a laying layer having an upper surface made of a hydrated hardened body, as described in claim 1, characterized in that the average thickness of the layer is at least 2 / 5 of the maximum dimension of the coarse aggregate.

3. The placed paste (p) forms a paste layer (p) having an average thickness of 10 mm or more and 30 mm or less on the coarse aggregate layer (a). Ｌ 3. A method for constructing a laying layer having an upper surface made of a hydrated hardened body according to claim 1 or 2, characterized in that

4. A method for constructing a laying layer having an upper surface made of a hydrated hardened body, as described in claim 1, characterized in that the paste (p) is made by replacing 50% to 70% of the cement weight with blast furnace slag powder as a binder.

5. The method for constructing a laying layer having an upper surface made of a hydrated hardened body according to claim 1, characterized in that the weight ratio of binder to water (binder:water) of the paste (p) is 1:0.5 to 0.

6.

6. The method for constructing a laying layer having an upper surface made of a hydrated hardened body according to claim 1, characterized in that the paste (p) is mortar, and the weight ratio of binder to fine aggregate is 1:3 to 5.

7. A method for constructing a laying layer having an upper surface made of a hydrated hardened body, as described in claim 1, characterized in that the paste (p) is mortar and more than 50% by weight of the fine aggregate is blast furnace slag fine aggregate.

8. The paste (p) is a mortar in which 50% to 70% of the cement weight is replaced with ground granulated blast furnace slag as a binder, and 50% by weight or more of the fine aggregate is blast furnace slag fine aggregate; The placed paste (p) forms a paste layer (p) having an average thickness of 10 mm or more and 30 mm or less on the coarse aggregate layer (a). Ｌ ) is formed, The paste filling portion (a) is formed only in the upper region of the coarse aggregate layer (a). ｐ ) is formed, and the paste filling portion (a ｐ 2. A method for constructing a laying layer having an upper surface made of a hydrated hardened body, as described in claim 1, characterized in that the average thickness of the layer is at least 2 / 5 of the maximum dimension of the coarse aggregate.

9. The method for constructing a laying layer whose upper surface is made of a hydrated hardened body according to claim 1 or 8, characterized in that the paste (p) is made by adding a chemical admixture containing a lignin sulfonic acid compound and a polycarboxylic acid ether as ingredients in an amount of 0.5% to 1% of the binder weight, and the weight ratio of the binder to the total of water and chemical admixture (binder:water+chemical admixture) is 1:0.45 to 0.

54.

10. A method for constructing a laying layer having an upper surface made of a hydrated hardened body, as described in claim 4 or 8, characterized in that the paste (p) is mortar, the fine aggregate is made of blast furnace slag fine aggregate, and further, blast furnace slag powder is added as an admixture in an amount of 20±5% of the binder weight.

11. 2. A method for constructing a laying layer whose upper surface is made of a hydrated hardened body according to claim 1, wherein the upper surface of the laying layer is a foundation marking surface.

12. A laying layer constructed on the ground, the upper surface of which is made of a hydrated hardened body, The coarse aggregate layer (A) is constructed by spreading coarse aggregate on the ground, and a hydrated hardened body using cement as a binder (including a hydrated hardened body in which part of the cement is replaced with ground granulated blast furnace slag). The hydrated hardened body filling section (A) is filled in the voids in at least the upper region of the coarse aggregate layer (A). ｐ ) and has a hydrated hardened body (B) in which the upper surface of the coarse aggregate layer (A) is buried.

13. The hydrated hardened body filling portion (A) of the coarse aggregate layer (A) ｐ 13. The laying layer having an upper surface made of a hydrated hardened body as described in claim 12, characterized in that the average thickness of the layer is 2 / 5 or more of the maximum dimension of the coarse aggregate.

14. A hydrated hardened material layer (B) having an average thickness of 10 mm or more and 30 mm or less is placed on the coarse aggregate layer (A). Ｌ 14. The laying layer according to claim 12 or 13, wherein the upper surface is made of a hydrated hardened body.

15. The laying layer having an upper surface made of a hydrated hardened body as described in claim 12, characterized in that the hydrated hardened body (B) is a binder in which 50% or more and 70% or less of the cement weight is replaced with granulated blast furnace slag.

16. A laying layer having an upper surface made of a hydrated hardened body as described in claim 12, characterized in that the hydrated hardened body (B) is mortar and 50% by weight or more of the fine aggregate is blast furnace slag fine aggregate.

17. The hydrated hardened body (B) is a mortar in which 50% to 70% by weight of cement is replaced with ground granulated blast furnace slag as a binder, and 50% by weight or more of the fine aggregate is blast furnace slag fine aggregate; A hydrated hardened material layer (B) having an average thickness of 10 mm or more and 30 mm or less is placed on the coarse aggregate layer (A). Ｌ ) is formed, The hydrated hardened body filling portion (A) is formed only in the upper region of the coarse aggregate layer (A). ｐ ) is formed, and the hydrated hardened body filling part (A ｐ 13. The laying layer having an upper surface made of a hydrated hardened body as described in claim 12, characterized in that the average thickness of the layer is 2 / 5 or more of the maximum dimension of the coarse aggregate.

18. 13. The laying layer having an upper surface made of a hydrated hardened body according to claim 12, characterized in that the upper surface of the laying layer is a foundation marking surface.

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