Curing method and method for manufacturing pavement concrete

Abstract

To provide a curing method capable of providing a relatively large slippage resistance value of a pavement concrete surface in which a concrete composition is cured, and a preparing method of the pavement concrete.SOLUTION: In a curing method related to the present invention, a concrete composition is cured after driving the kneaded concrete composition, including a water spraying step of spraying carbonated water to the surface of the driven concrete composition.SELECTED DRAWING: None

Description

【Technical Field】 【0001】 The present invention relates to a curing method and a method for manufacturing paving concrete. 【Background Art】 【0002】 Conventionally, the surface of paving concrete is required to have excellent skid resistance against vehicles and the like. Paving concrete is generally manufactured by pouring a concrete composition to be paving concrete into a formwork and then curing it to harden the concrete composition. At that time, for the purpose of sufficiently curing the concrete composition and preventing evaporation of moisture, rapid temperature changes, etc., water is sprayed on the surface of the concrete composition, for example, as described in Non-Patent Document 1. 【Prior Art Documents】 【Non-Patent Documents】 【0003】 【Non-Patent Document 1】 Japan Road Association, "Cement Concrete Pavement Guidelines", February 1984 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 However, although the paving concrete obtained by using the conventional curing method is sufficiently hardened by curing, there is a problem that the skid resistance on its surface is small. Therefore, a curing method capable of obtaining a paving concrete surface excellent in skid resistance is required. 【0005】 The present invention has been made in view of such a situation, and an object thereof is to provide a curing method and a method for manufacturing paving concrete that can relatively increase the skid resistance value of the surface of paving concrete in which a concrete composition has hardened. 【Means for Solving the Problems】 【0006】 The curing method according to the present invention is a curing method for hardening a concrete composition after it has been poured, The process includes a watering step of spraying carbonated water onto the surface of the poured concrete composition. 【0007】 The curing method according to the present invention, with this configuration, can make the slip resistance of the pavement concrete surface after the concrete composition has hardened relatively high. 【0008】 In the curing method according to the present invention, the watering step may be performed after the final setting time in the concrete. 【0009】 The curing method according to the present invention, with this configuration, can increase the slip resistance value of the pavement concrete surface after the concrete composition has hardened. 【0010】 In the curing method according to the present invention, the watering step may be performed within 17 hours from the end of the concrete setting time. 【0011】 The curing method according to the present invention, with this configuration, can increase the slip resistance value of the pavement concrete surface after the concrete composition has hardened. 【0012】 In the curing method according to the present invention, the carbon dioxide concentration of the carbonated water may be set to 0.2 g / L or higher. 【0013】 The curing method according to the present invention, with this configuration, can increase the slip resistance value of the pavement concrete surface after the concrete composition has hardened. 【0014】 The present invention relates to a method for producing pavement concrete, which involves hardening a concrete composition to produce pavement concrete. The concrete composition is hardened using the curing method described above. 【0015】 The manufacturing method of the paving concrete according to the present invention can produce paving concrete having a relatively large skid resistance value with such a configuration. 【0016】 The manufacturing method of the paving concrete according to the present invention may set the skid resistance value (BPN) on the surface of the paving concrete to 60 or more. 【0017】 The manufacturing method of the paving concrete according to the present invention can further suppress slips of tires of automobiles or the like with such a configuration. 【Effect of the Invention】 【0018】 According to the present invention, it is possible to provide a curing method and a manufacturing method of paving concrete that can relatively increase the skid resistance value of the surface of the paving concrete in which the concrete composition is cured. 【Modes for Carrying Out the Invention】 【0019】 Hereinafter, the curing method and the manufacturing method of paving concrete according to the present embodiment will be described. 【0020】 <Curing Method> The curing method according to the present embodiment is a curing method for curing the kneaded concrete composition after driving it, and includes a watering step of watering carbonated water on the surface of the driven concrete composition. 【0021】 The concrete composition cured by the curing method according to the present embodiment includes, for example, cement, aggregate, and water. 【0022】 The cement is not particularly limited, and for example, Portland cement such as ordinary Portland cement, rapid hardening Portland cement, super rapid hardening Portland cement, medium heat Portland cement, sulfate resistant Portland cement, white Portland cement, etc. defined in JIS R 5210:2019; Mixed cements such as blast furnace cement, fly ash cement, silica cement, etc.; Known cements such as super high early strength cement, alumina cement, etc. can be used. Note that the cement may be used alone or in combination of two or more kinds. 【0023】 As the aggregate, fine aggregate and / or coarse aggregate can be used. Note that the fine aggregate refers to an aggregate that completely passes through a 10 mm sieve and passes through a 5 mm sieve by 85% or more in mass, and the coarse aggregate refers to an aggregate that remains at 85% or more in mass on a 5 mm sieve (JIS A 0203:2019). 【0024】 Examples of the fine aggregate include sands derived from natural products such as river sand, land sand, mountain sand, sea sand, crushed sand, limestone crushed sand, etc. defined in JIS A 5308:2019 Appendix A Ready-mixed concrete aggregate, blast furnace slag, etc. Note that the fine aggregate may be used alone or in combination of two or more kinds. 【0025】 Examples of the coarse aggregate include natural aggregates such as river gravel, mountain gravel, sea gravel, etc., artificial aggregates such as crushed stones of sandstone, hard limestone, basalt, andesite, etc., recycled aggregates, etc. Note that the coarse aggregate may be used alone or in combination of two or more kinds. 【0026】 The water is not particularly limited, and for example, tap water, industrial water, recovered water, groundwater, river water, rainwater, etc. can be used. It is preferable that the water does not contain organic substances, chloride ions, sodium ions, potassium ions, etc. that have an adverse effect on the hydration reaction of the concrete composition and the paving concrete, or contains them only in extremely small amounts. More preferably, the water is tap water or industrial water with stable quality. 【0027】 Furthermore, the concrete composition may contain admixtures. Examples of admixtures include inorganic powders such as fly ash, silica fume, cement kiln dust, blast furnace fume, blast furnace granulated slag powder, blast furnace decoction slag powder, converter slag powder, hemihydrate gypsum, expansive agents, limestone powder, quicklime powder, dolomite powder, sodium-type bentonite, calcium-type bentonite, attapulgite, sepiolite, activated clay, acid clay, allophane, imogolite, shirasu (volcanic ash), shirasu balloon, kaolinite, metakaolin (calcined clay), synthetic zeolite, artificial zeolite, mordenite, clinoptilolite, and other inorganic fillers. Note that one type of admixture may be used alone, or two or more types may be used in combination. 【0028】 Furthermore, the concrete composition may contain admixtures. Examples of admixtures include air-entraining agents, air-entraining water-reducing agents, high-performance air-entraining water-reducing agents, fluidizers, segregation-reducing agents, setting retarders (e.g., tartaric acid), setting accelerators (e.g., aluminum sulfate), rapid setting agents, shrinkage-reducing agents, foaming agents, foaming agents, and waterproofing agents. Note that one type of admixture may be used alone, or two or more types may be used in combination. 【0029】 The water / cement ratio used when forming a concrete composition is not particularly limited and can be varied depending on the type and proportions of cement and other materials used. The water / cement ratio is the mass percentage of water relative to cement. Preferably, the water / cement ratio is 30% by mass or more and 60% by mass or less, and more preferably 35% by mass or more and 50% by mass or less. 【0030】 The curing method according to this embodiment includes a watering step. The watering step is a step of spraying carbonated water onto the surface of the poured concrete composition. 【0031】 During the watering process, carbonated water is sprayed onto the surface of the poured concrete composition, covering the surface with carbonated water. Covering the surface with carbonated water prevents evaporation of moisture from the concrete composition and rapid temperature changes, while the carbonated water acts on the surface, roughening it. This increases the skid resistance value of the hardened pavement concrete surface. 【0032】 Skid resistance refers to the frictional resistance generated between the hardened concrete surface of a paved concrete composition and the tires of an automobile, etc. A higher skid resistance value makes it less likely to slip, while a lower value makes it more likely to slip. In this specification, skid resistance is expressed in BPN (British Pendulum Number). BPN is the skid resistance value measured using a tester (portable skid resistance tester) developed by the British Road Research Institute. 【0033】 The skid resistance value (BPN) of the pavement concrete surface of the concrete composition hardened by the curing method according to this embodiment is preferably high from the viewpoint of suppressing slippage of automobile tires and the like. The skid resistance value (BPN) is preferably 60 or higher. 【0034】 The timing of the watering process is not particularly limited and can be carried out after a predetermined time has elapsed since the concrete composition was poured. 【0035】 In this process, the timing of the watering step may be based on the time the concrete composition was poured, but since the degree of hardening progress differs depending on the type and mix of cement and other materials used, it is preferable to base the timing on the degree of hardening progress of the concrete composition. 【0036】 When using the degree of hardening of a concrete composition as a criterion, the reference time can be the start time or end time of concrete setting. The effect of carbonated water on the surface of the concrete composition becomes greater as a certain degree of hardening progresses. Therefore, it is preferable to use the end time, which is when a certain degree of hardening has progressed, as the criterion. Using the end time as the criterion makes it easier to manage the timing of the watering process. Note that the start time of concrete setting is defined in the concrete setting time test method specified in JIS A1147:2019, where the penetration resistance of the concrete composition is 3.5 N / mm². 2 This is the time it takes until the concrete sets. Furthermore, the final setting time in concrete is defined in the concrete setting time test method specified in JIS A1147:2019, where the penetration resistance of the concrete composition is 28.0 N / mm². 2 This is the time it takes to reach that point. 【0037】 As mentioned above, the effect of carbonated water on the surface of the concrete composition becomes greater as hardening progresses to a certain extent. Therefore, the watering process is preferably carried out after the end of the concrete setting time, from the viewpoint of increasing the slip resistance value of the pavement concrete surface after the concrete composition has hardened. Also, if the hardening of the concrete composition progresses too far, the effect of carbonated water on the surface of the concrete composition will decrease. Therefore, the watering process is preferably carried out within 17 hours of the end of the concrete setting time. 【0038】 Furthermore, after covering the surface of the concrete composition with carbonated water during the watering process, carbonated water may be supplied again to prevent the surface of the concrete composition from drying out until the concrete composition has sufficiently hardened. 【0039】 The carbonated water used in the watering process is not particularly limited as long as it contains carbon dioxide gas. From the viewpoint of increasing the slip resistance value of the pavement concrete surface after the concrete composition has hardened, the concentration of carbon dioxide in the carbonated water is preferably 0.2 g / L or more, and more preferably 1.7 g / L or more. 【0040】 The curing method according to this embodiment, by including a watering step, can make the slip resistance value of the hardened pavement concrete surface relatively high. 【0041】 In the curing method according to this embodiment, a method of directly spraying carbonated water onto the poured concrete composition during the watering step has been described. However, as another embodiment of the curing method, a curing mat (curing sheet) may be laid on the poured concrete composition during the watering step, and carbonated water may be sprayed on top of the mat. The curing mat is not particularly limited as long as it is absorbent. For example, a cloth curing mat can be used, and any known curing mat with absorbency, such as a napped material or pile material, may be used. 【0042】 In another aspect of the curing method, using a curing mat in the watering process allows the concrete composition to relatively increase the slip resistance value of the hardened pavement concrete surface, and also allows the carbonated water on the surface of the concrete composition to be retained for a longer period of time. 【0043】 Furthermore, the curing method according to this embodiment may include a surface texture manufacturing step in which irregularities are created on the surface of the poured concrete composition before the watering step. Examples of known methods for creating irregularities on the surface of the concrete composition in the surface texture manufacturing step include, for example, a broom finish using a broom, and a ring method using a rubber-like ring. 【0044】 The surface texture manufacturing process creates irregularities on the surface of the concrete composition poured before the watering process. Therefore, a curing method that includes a surface texture manufacturing process can synergistically increase the slip resistance value of the hardened pavement concrete surface. 【0045】 <Method of manufacturing paving concrete> The method for manufacturing pavement concrete according to this embodiment is a method for manufacturing pavement concrete by hardening a concrete composition, wherein the concrete composition is hardened by the curing method described above. 【0046】 The surface slip resistance value (BPN) of the pavement concrete manufactured by the pavement concrete manufacturing method according to this embodiment is preferably high from the viewpoint of suppressing slippage of automobile tires, etc. The slip resistance value (BPN) is preferably 60 or higher. By setting the surface slip resistance value (BPN) of the pavement concrete to 60 or higher, slippage of automobile tires, etc. can be further suppressed. 【0047】 It should be noted that the curing method and pavement concrete manufacturing method according to this embodiment are not limited to the above embodiment, and various modifications are possible without departing from the gist of the disclosure in this application. 【0048】 The present invention includes the following embodiments. [1] A curing method for hardening a concrete composition after it has been poured, A curing method comprising a watering step of spraying carbonated water onto the surface of a poured concrete composition. [2] The curing method described in [1] above, wherein the watering process is performed after the end time in concrete setting. [3] The curing method according to [1] or [2] above, wherein the watering process is carried out within 17 hours of the end of the concrete setting time. [4] A treatment method described in any one of the above [1] to [3], wherein the carbon dioxide concentration of the carbonated water is 0.2 g / L or higher. [5] A method for producing pavement concrete by hardening a concrete composition, A method for manufacturing pavement concrete, wherein the concrete composition is hardened by any one of the curing methods described in [1] to [4] above. [6] A method for manufacturing pavement concrete as described in [5] above, wherein the surface of the pavement concrete has a slip resistance value of 60 or more. [Examples] 【0049】 The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments. 【0050】 (Preparation of test specimens) Table 1 shows the components contained in concrete composition 1 and concrete composition 2. Concrete composition 1 and concrete composition 2 were prepared by mixing each component except water, dry mixing for 15 seconds, then adding water and mixing for 60 seconds. Each prepared concrete composition was poured into a formwork (30 cm × 30 cm × 4.5 cm), and the surface was finished with a trowel to produce concrete slab specimens. 【0051】 Details of each component shown in Table 1 are provided below. Cement (NC): Ordinary Portland cement (manufactured by Sumitomo Osaka Cement Co., Ltd.), density 3.15 g / cm³ 3 Cement (HC): High-early-strength Portland cement (manufactured by Sumitomo Osaka Cement Co., Ltd.), density 3.13 g / cm³ 3 Water: Tap water Fine aggregate: Mountain sand F.M2.62 (produced in Kakegawa City), density 2.58 g / cm³ 3 Coarse aggregate: Crushed stone 2005 F.M6.67 (from Nishiibaraki district), density 2.65 g / cm³ 3 【0052】 [Table 1] 【0053】 (Curing of test specimens) <Example 1> At 5 hours after placement (2.5 hours before the end of concrete setting) of a test specimen using concrete composition 1, 2.2 L / m³ of carbonated water with a CO2 concentration of 1.7 g / L was added. 2 The specimen was then sprayed with water. Afterwards, the same carbonated water (2.2 L / m²) was applied to the surface of the specimen to prevent it from drying out. 2The concrete was watered twice. Table 2 shows the conditions for each watering. Note that in Table 2, a negative value for the concrete setting completion time at the watering timing indicates a time before the completion time. 【0054】 <Examples 2-5> The only difference from Example 1 was the timing of spraying the carbonated water. The conditions for Examples 2-5 are shown in Table 2. 【0055】 <Examples 6-9> The conditions for Examples 6-9 are the same as in Example 1, except that concrete composition 2 was used to prepare the test specimens and the timing of spraying with carbonated water was changed. The conditions for each of Examples 6-9 are shown in Table 2. 【0056】 <Examples 10-13> The only differences from Example 1 are that the carbon dioxide concentration of the carbonated water was set to 0.2 g / L and the timing of spraying the carbonated water was changed. The conditions for each of Examples 10 to 13 are shown in Table 2. 【0057】 <Examples 14-17> Examples 10 to 13 are the same as Example 1, except that concrete composition 2 was used to prepare the specimens, the carbon dioxide concentration of the carbonated water was set to 0.2 g / L, and the timing of spraying the carbonated water was changed. The conditions for each of Examples 10 to 13 are shown in Table 2. 【0058】 <Comparative Example 1> The procedure is the same as in Example 1, except that tap water was used for watering. Table 2 shows the conditions for each case. 【0059】 <Comparative Examples 2-5> Aside from changing the timing of watering with tap water, the conditions for Comparative Examples 2-5 are the same as in Comparative Example 1. The conditions for Comparative Examples 2-5 are shown in Table 2. 【0060】 <Comparative Examples 6-10> The conditions for Comparative Examples 6-10 are the same as in Comparative Example 1, except that concrete composition 2 was used to prepare the test specimens and the timing of watering with tap water was changed. The conditions for Comparative Examples 6-10 are shown in Table 2. 【0061】 <Comparative Example 11> The procedure is the same as in Example 1, except that the test specimens are cured in air. Table 2 shows the conditions for each case. 【0062】 <Comparative Example 12> The procedure was the same as in Comparative Example 11, except that concrete composition 2 was used in the preparation of the test specimens. Table 2 shows the conditions for each case. 【0063】 (Measurement of sliding resistance value) In accordance with "S021 Method for Measuring the Skid Resistance of Pavement Surfaces" in the Pavement Survey and Testing Methods Handbook [Volume 1], the skid resistance value (BPN) was measured for each example and comparative example one week after the start of curing. The measurement results for Examples 1 to 17 and Comparative Examples 1 to 12 are shown in Table 2. 【0064】 [Table 2] 【0065】 Table 2 shows that curing by spraying carbonated water resulted in a higher slip resistance value on the surface of the hardened concrete composition compared to curing by spraying tap water or curing in air. 【0066】 Furthermore, since concrete compositions 1 and 2, which use different types of cement, have different hardening times, if the elapsed time from the time of placement is used as the basis, the timing of watering must be different in order to achieve similar sliding resistance values. On the other hand, if the final setting time of the concrete is used as the basis, it was possible to achieve similar sliding resistance values ​​by using the same timing of watering. Therefore, it is clear that using the final setting time of the concrete as the basis makes it easier to control the timing of watering the concrete composition.

Claims

[Claim 1] A curing method for hardening a mixed concrete composition after it has been placed, The process includes a watering step of spraying carbonated water onto the surface of the poured concrete composition. A curing method in which the watering process is carried out after the completion time of concrete setting. [Claim 2] The curing method according to claim 1, wherein the watering process is carried out within 17 hours of the completion time in concrete setting. [Claim 3] The curing method according to claim 1 or 2, wherein the carbon dioxide concentration of the carbonated water is 0.2 g / L or more. [Claim 4] A method for manufacturing pavement concrete by hardening a concrete composition, A method for producing pavement concrete, comprising hardening a concrete composition by the curing method described in claim 1 or 2. [Claim 5] A method for manufacturing pavement concrete according to claim 4, wherein the surface slip resistance value (BPN) of the pavement concrete is 60 or more.

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