JP6401323B2 - All-weather curing method for concrete - Google Patents

Description

  The present invention relates to a concrete curing method, and more particularly to a method capable of curing mass concrete (massive concrete) in the same manner throughout the year (all weather).

  According to the concrete standard specification, there are three types of concrete curing methods. When the daily average temperature falls below 4 ° C, it is called cold concrete, and when it exceeds 25 ° C, it is hot concrete. It is instructed to avoid drastic drying and temperature changes, and a daily curing temperature of 4 ° C. to 25 ° C. or the like indicates a normal curing guideline as general concrete. Furthermore, in the case of cold concrete, in order to avoid rapid cooling of the concrete surface, there is an example in which, at the end of curing, the temperature is not exceeded by more than 17 ° C. within 24 hours.

  Therefore, a curing temperature pattern is set for each outside air temperature so that the curing method can be selected according to these daily average temperatures, and the curing temperature pattern is selected according to the outside air temperature at the construction site. It has been proposed to carry out curing based on a temperature pattern (see Patent Document 1). The curing method based on this curing temperature pattern distinguishes between the case of hot concrete and the case of cold concrete from the outside temperature, and controls the curing temperature according to them. It was something to change.

  However, since the curing temperature in the case of hot concrete or cold concrete is naturally different, the temperature change along the patterned curing temperature is controlled by a heater or the like, and heating of the heater is used. At the same time, analysis of the temperature heated by the heater is indispensable. For this reason, not only a heater but also other devices are required, resulting in an expensive curing system.

  On the other hand, a configuration has been proposed in which water (or hot water) whose temperature is adjusted from a water supply tank in order to maintain a wet state in both cases of hot concrete and cold concrete (see Patent Document 2). In this case, the temperature of the concrete is adjusted by adjusting the temperature of the water, and the wet state is maintained by supplying the water. However, the relationship with the outside air temperature is important for adjusting the temperature. A water supply tank must be placed above the concrete (above the formwork), which is a large scale and requires a pump for supplying water to the tank, which is also expensive. It was.

JP 2005-344437 A JP 2006-183264 A JP 2013-174047 A Japanese Patent Application Laid-Open No. 2006-89381

  The conventional technology as described above is large-scale and tends to be high in cost. As a curing method that can be easily installed and removed at low cost, a method for obtaining a heat retaining effect by a sheet has been proposed. (See Patent Documents 3 and 4). Since these use sheets for heat insulation, they are limited to curing methods for cold concrete.

  By the way, the curing of cold concrete is required to be kept at 5 ° C. or higher until the compressive strength is obtained, and further to be kept at 0 ° C. or higher for 2 days according to the concrete standard specification. In order to satisfy this, a sheet having heat retention was used.

  However, these heat insulating sheets can be used only in cold concrete, and cannot be used in other curing, particularly in hot concrete. In general, in the construction of hot concrete, according to the standard specifications for concrete, the concrete at the time of placing is set to 35 ° C. or less, and during curing, protection from rapid drying of the surface is required. Insulation effect is not required. For this reason, watering and the like have been performed to maintain moisture.

  The purpose of these curings was to suppress the occurrence of cracks by preventing rapid cooling of the surface temperature in cold concrete and rapid drying in hot concrete. Therefore, these curing sheets cannot be used in a state that is neither cold concrete nor hot concrete, and as a result, different curing sheets have been used.

  The present invention has been made in view of the above points, and its purpose is to propose an all-weather concrete curing method that does not need to be selectively changed according to climate, weather, etc. It is to provide a high-quality and solid concrete structure.

  As a result of diligent research, the present inventors have paid attention to the fact that the cause of cracks occurring in concrete is the temperature stress due to the difference between the internal temperature and the surface temperature. By suppressing the decrease in the surface temperature at the time within 17 ° C., it was possible to lead a curing method capable of suppressing the occurrence of cracks without distinguishing between cold concrete and hot concrete.

Therefore, the present invention is a method for curing concrete, wherein the heat transfer coefficient is set to 3.8 W / m ² ° C. or less by a laminate of a heat shield sheet and a heat insulating sheet, and the laminate is cured while keeping the heat shield sheet inside. By covering the surface of the concrete to be reinforced and further covering the surface of the laminate with a light-shielding sheet, the heat of hydration and moisture generated from the concrete after placement is retained in the concrete and generated by the heat of hydration. It is characterized by suppressing the decrease in the surface temperature by using radiant heat and suppressing drying due to evaporation of moisture.

According to the said structure, since the heat transfer rate by a laminated body is 3.8 W / m < ² > (degreeC) or less, the hydration heat which generate | occur | produces with the cast concrete can be utilized to the maximum. That is, the heat radiated from the concrete can act as radiant heat, the temperature of the concrete surface temperature can be prevented from decreasing, and the difference from the internal temperature can be prevented from being greatly enlarged. At the same time, it is possible to prevent the surface from drying by suppressing the evaporation of the water inside the concrete. Thus, by reducing the temperature difference between the internal temperature and the surface temperature, the occurrence of cracks due to temperature stress can be suppressed, and the occurrence of cracks due to drying of the surface can also be suppressed at the same time. Furthermore, by decreasing the internal temperature and the surface temperature of the concrete sufficiently and gradually until the end of the curing period, the temperature drop at the end of the curing can be made within a predetermined range.

Further, the present invention is a concrete curing method, and the temperature analysis during curing with the laminate is performed on the assumption that the laminate of the heat shield sheet and the heat insulating sheet has a heat transfer coefficient of 3.8 W / m ² ° C or less. In the case where all the values during the curing period of the crack index calculated with reference to the temperature difference between the internal temperature and the surface temperature of the concrete based on the temperature analysis are 1.0 or more, during the curing period, The concrete surface is covered with the heat shield sheet of the laminate having a heat transfer coefficient of 3.8 W / m ² ° C or less inside, and the surface of the laminate is further covered with the light shield sheet. It is.

According to the present invention, in the temperature analysis performed during curing of concrete, the heat transfer coefficient of the sheet (laminate) used during curing is set to 3.8 W / m ² ° C or less as the condition, and the internal temperature and the surface temperature are set as the conditions. Since the analysis is carried out when the crack index during the curing period is 1.0 or more after analysis, the occurrence of cracks is suppressed on the planned curing based on the analysis result. And, by setting the heat transfer coefficient of the laminate used for curing concrete to 3.8 W / m ² ° C or less, the internal temperature and surface temperature during the curing period are gradually decreased due to temperature changes in accordance with the analysis results. Can be made.

  In the curing method of the above configuration, the curing period can be defined as a period in which the temperature drop at the end of curing is 17 ° C. or less based on the analysis temperature.

  In the case of such a configuration, during concrete curing in the winter season when the outside air temperature is relatively low, it is possible to suppress a rapid decrease in the surface temperature after completion of curing (after removal of the laminated body or the like). Therefore, in the curing of cold concrete, concrete curing can be performed by the same curing method. In summer, when the outside air temperature is relatively high, it is not necessary to take into account the sudden temperature drop after the end of curing, but in order to prevent the curing from being terminated without the internal temperature decreasing, the same process may be used. It ’s good.

  Moreover, this invention is good also as a structure which laminates | wraps a wrapping sheet inside the said laminated body in the surface which is not protected by the formwork among the concrete which should be hardened in the structure in any one of said.

  According to the above configuration, the surface of the placed concrete that is protected by the mold is to avoid moisture evaporation by the mold, but the surface that is not protected by the mold is There is a concern that moisture evaporates from the surface, causing a temperature drop due to heat of vaporization and cracking due to drying of the surface. Therefore, by laminating a wrapping sheet on the inside of the laminate, the first coating material on the concrete surface becomes a wrapping sheet, suitably preventing evaporation of the moisture and preventing drying, and eliminating cracks due to drying. It will be.

  Furthermore, the present invention may be configured such that, in the above configuration, the surface of the light shielding sheet is covered with a waterproof sheet to block the supply of moisture to the cast concrete. In this case, it is possible to eliminate the supply of water that evaporates due to the supply of water to the concrete surface or the surface of the light shielding sheet, and to prevent a temperature decrease due to heat of vaporization.

Further, the present invention is a concrete curing method using a laminate having a heat transfer coefficient of 3.8 W / m ² ° C or less formed by a heat insulating sheet and a heat insulating sheet, and a placing stage curing process, A stage curing process, and the placing stage curing process covers the surface of the formwork on the side of the concrete where the placed concrete is blocked by the formwork, with the heat shield sheet of the laminate inside. Further, the surface is covered with a light-shielding sheet, and a wrapping sheet is adhered to the upper surface of the placed concrete, and the heat-shielding sheet of the laminate is covered inside, and the surface is further shielded from light. The mold release step curing process is performed on each of the side surface of the concrete after removing the formwork and the upper surface of the cast concrete. , After brought into close contact with the wrapping sheet on the surfaces, said coated with a thermal barrier sheet of the laminate on the inside, is characterized in that the further coating the surface by the light shielding sheet.

  According to the above configuration, the period from concrete placement to mold release and the period after mold release are separated, and in the curing (formation stage curing process) when the mold is installed, For the concrete side that is blocked and protected by the frame, the function of the wrapping sheet is replaced by the mold. In addition, the moisture in the concrete evaporates by the lapping sheet on the surface of the portion where the mold is not installed in the placement stage curing process and the entire surface in the state after removing the mold (mold release stage curing process). It restricts that.

  In one or both of the placing stage curing process and the release stage curing process having the above-described configuration, the present invention may further cover at least the upper surface of the concrete and further cover the surface of the light shielding sheet with a waterproof sheet.

  According to the said structure, the inflow of rain water at the time of rainy weather can be prevented, and a moist state can be maintained only with the water | moisture content which exists in concrete inside. That is, since the effect of preventing evaporation by the wrapping sheet is used and watering to the concrete is unnecessary, supply of excess moisture can be suppressed.

  Moreover, this invention is good also as a structure which further includes the lapping process which coat | covers a concrete surface only by a lapping sheet after completion | finish of a curing process. In this case, even after completion of the curing process that does not require surface management, it can be moistened when the humidity is low and there is a risk of drying. That is, the generation of cracks due to drying of the concrete surface can be suppressed.

The present invention suppresses the occurrence of cracking due to temperature stress by setting the temperature difference between the inside and the surface of the concrete within a predetermined range during curing of the concrete, and further sets the temperature drop on the concrete surface at the end of curing. The occurrence of cracks due to temperature stress can also be suppressed by setting it within the range. Therefore, the heat transfer sheet and the heat insulating sheet laminate have a heat transfer coefficient of 3.8 W / m ² ° C. or less, and the concrete is maintained in a suitable temperature environment on the inner side covered by the laminate. The temperature difference can be made as small as possible.

  That is, when curing cold concrete, the function of the heat insulating sheet and the heat insulating sheet can be used to suppress a decrease in surface temperature and to effectively maintain the temperature by effectively utilizing the heat of hydration. In addition, by covering the surface of the laminate with a light-shielding sheet, the effect of heat from sunlight can be suppressed by blocking or reflecting sunlight in fine weather. It eliminates changes in temperature.

  On the other hand, when curing concrete in the summer, the temperature increase due to sunlight is suppressed by the light-shielding sheet coated in the outermost layer, and further, the outside temperature is prevented from increasing the surface temperature of the concrete by the heat insulating sheet. As a result, the heat of hydration inside the concrete becomes the sole heat source, preventing the expansion of the temperature difference between the inside and the surface.

  In addition, even if it does not fall under either the cold concrete or the hot concrete, the temperature control using the heat of hydration will be performed as a result, and the expansion of the temperature difference between the inside and the surface will be suppressed, and cracks will occur. The cause of this can be eliminated. In this way, it can be cured by the same method regardless of the season and weather conditions, so it is not necessary to distinguish between cold and hot (without measuring the daily average temperature) and annually. Through this, all-weather curing methods that do not affect the season or climate will be realized. This makes it possible to provide high-quality and solid concrete structures throughout the year.

It is explanatory drawing which shows the outline | summary of the coating sheet used for the curing method of this invention. It is explanatory drawing which shows the construction procedure of a concrete structure. It is explanatory drawing which shows the procedure of the all-weather type curing method of concrete. It is explanatory drawing which shows the specific method of curing. It is explanatory drawing which shows the specific method of curing. It is explanatory drawing which shows the specific method of curing. 6 is a graph showing the results of Experiment 1. 10 is a graph showing the results of Experiment 2.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a covering sheet used for curing concrete in this embodiment. FIG. 1 (a) shows the case on the surface where the mold does not exist, and FIG. 1 (b) shows the case on the surface having the mold.

  As shown to Fig.1 (a), since the formwork does not exist in the concrete surface X, the surface X is the structure directly coat | covered with a some sheet | seat. The concrete surface X is first covered with the wrapping sheet 1. The wrapping sheet 1 is a transparent resin sheet and is composed of a thin resin sheet having a thickness of 1 mm or less. The sheet material is made of a synthetic resin such as polyethylene or polypropylene, and prevents moisture from evaporating from the concrete surface X by being in close contact with and covering the concrete surface X.

  Further, the surface of the wrapping sheet 1 is covered with a heat shield sheet 2. The heat shield sheet 2 is to shield heat by reflecting the radiant heat emitted from the concrete surface X. The cast concrete generates heat of hydration inside, and the heat acts as radiant heat outward from the surface X, and is reflected by the heat shield sheet 2. The reflection of radiant heat can be made of a metal material, and an aluminum sheet material can be used, or a sheet material obtained by laminating an aluminum thin film on the surface of a resin sheet can be used.

Further, the surface of the heat insulating sheet 2 is covered with a heat insulating sheet (heat insulating sheet) 3. When the concrete is heated to high temperature by heat of hydration, this heat is conducted to the outside and cooled from the surface X. Therefore, the concrete is provided for keeping warm. In order to improve the heat retaining effect (heat insulating effect), a heat insulating material is used, but a sheet material having an air layer (having bubbles) structure is used. As the heat insulating sheet 3, a plastic corrugated cardboard can be used, and an air bubble plastic sheet can be used. Moreover, you may use the independent foam sheet formed by a polyolefin film | membrane. The state in which the heat insulating sheet 2 and the heat insulating sheet 3 are laminated is the laminated body of the present invention. In the state of the laminated body formed by laminating both the sheets 2 and 3, the heat transfer coefficient is It will be 3.8 W / m ² ° C or less.

Further, the surface of the heat insulating sheet 3 is covered with a light shielding sheet (reflective sheet) 4. The light shielding sheet 4 is for blocking irradiation with sunlight, and a high-density polyethylene nonwoven fabric or an agricultural multi-sheet can be used, and light shielding by a reflection effect by a metal material may be performed. The reflection by the metal material prevents the temperature from rising due to the reflection of the radiant heat by sunlight, and an aluminum sheet material may be used in the same manner as the heat shield sheet 2. As described above, in order to set the heat transfer coefficient to 3.8 W / m ² ° C or lower, the heat shielding sheet 2 and the heat insulating sheet 3 are laminated, but the light shielding sheet 4 is laminated on the surface. Therefore, the heat transfer coefficient is further reduced, and can be set to about 3.3 W / m ² ° C.

  By laminating these sheets, it is possible to suppress a rapid decrease in the internal temperature and the surface temperature of the concrete while maintaining the wet state of the concrete surface X. As a result, the occurrence of cracks due to temperature stress can be suppressed, and further, the generation of cracks due to drying of the concrete surface can be suppressed.

  On the other hand, as shown in FIG. 1B, when the concrete surface X is protected by the formwork Y, the wrapping sheet 1 is not used, and the heat shield sheet 2, the heat insulating sheet 3 and the light shield sheet 4 are used. The surface of the mold Y is covered. The fact that the concrete surface X is protected by the formwork Y means that the surface X is covered with the formwork Y so that the concrete surface X is not exposed and dried (moisture evaporation). The state in which the formwork Y protects the concrete surface X is installed around the concrete structure when it is constructed, and is exclusively the side surface of the concrete.

  In addition, in FIG. 1, the state which coat | covers the surface of the light-shielding sheet | seat 4 with a waterproof sheet is shown, and as shown in this figure, invasion of rain water etc. is prevented by coat | covering the whole with the waterproof sheet 5. It is also possible.

  By the way, when the concrete constructed by placing is massive (thick) concrete, the curing environment is analyzed in advance, and the curing period (end time) is determined based on the analysis result. In the analysis at this time, since the surface temperature and the internal temperature of the concrete are analyzed, the crack index can be calculated by referring to the analysis temperature. Specifically, “cracking index” = “tensile strength of concrete” / “temperature stress (maximum main tensile stress)”. Among these, the temperature stress is generated due to the difference between the internal temperature and the surface temperature of the concrete. Therefore, if the temperature difference is large, the temperature stress increases and the crack index decreases. In order to set the crack index to 1.0 or more, it is necessary to increase the “concrete tensile strength” or to reduce the “temperature stress”, but the “concrete tensile strength” However, this cannot be influenced by external factors. As a result, the crack index is increased (1.0 or more) by reducing the “temperature stress”.

In the above analysis, the influence of the outside air temperature must be taken into consideration, and factors of various temperature changes such as a temperature decrease due to radiation of heat of hydration or a temperature increase in a heating state by a heater are considered. . At that time, the ratio of the outside air temperature by the degree of heat transfer coefficient of the curing sheets used (or also referred to as a heat transfer coefficient) is affected is considered. Therefore, since the heat transfer coefficient of the laminate used in the present embodiment is 3.8 W / m ² ° C or less (substantially about 3.3 W / m ² ° C), the heat transfer of the curing sheet is performed during analysis. The rate is a numerical value within the range of 3.3 to 3.8 W / m ² ° C., which is the analysis condition. The relationship between the cracking index and the cracking probability is 50% when the index is 1.0, 15% when the index is 1.4, and 1.85 when the index is 1.85. In the case of, the probability of occurrence of cracks is 5%.

Thus, based on the result analyzed beforehand based on various conditions, the curing period is determined, and the crack index during that period (for each material age) is calculated. Then, in the analysis result, the concrete is cured under the condition that the crack index is 1.0 or more at all the ages during the period. Here, in the case of the present embodiment, heat from the heat transfer rate of the laminate is set heat transfer coefficient in the range of 3.3~3.8W / m ² ℃, from outside even in the analysis By using only the heat of hydration without the need for supply of water and without artificial cooling, and further eliminating the influence of sunlight, the crack index of 1.0 or more is maintained. It is possible to cure while.

  According to the configuration of the present embodiment, in the case of cold concrete (daily average temperature is 4 ° C. or less), the heat of hydration generated inside the concrete is insulated and kept warm by the laminated sheets without escaping to the outside. The temperature drop of the surface X can be prevented. Moreover, by decreasing concrete temperature gradually, the fall of the surface temperature at the time of completion | finish of curing can be maintained for 24 hours in the range within 17 degreeC. On the other hand, in the case of hot concrete (daily average temperature exceeds 25 ° C.), absorption of radiant heat by sunlight is suppressed and the outside air temperature and the concrete are blocked to prevent the temperature of the concrete from rising due to conduction heat. At the same time, moisture can be kept by suppressing evaporation of moisture from the surface. Therefore, a suitable curing state can be realized without distinction between summer and winter and also in an intermediate temperature environment.

  In addition, since it is the structure which provides the light shielding sheet 4 in order to reflect and shield the radiant heat by sunlight as mentioned above, it is preferable that the waterproof sheet 5 is a material which has a light transmittance. A material that does not absorb at least red light and infrared light having a wavelength of 600 nm or more is preferable. With such a material, the coated state can be continued in both cases of raining or sunny weather. In order to achieve such a state, for example, a sheet polyethylene laminated cloth sheet may be used in addition to the transparent vinyl sheet. According to such a laminated state, the same curing method can be used without distinction between fine weather and rainy weather.

  As described above, according to the present embodiment, it is possible to realize suitable curing of concrete in all weather types regardless of weather conditions throughout the year. In an environment where the daily average temperature is 4 ° C to 25 ° C, the concrete temperature is higher than the outside air temperature, but the heat of hydration inside the concrete is kept warm while the surface is kept moist. Therefore, the cause of the crack can be avoided by keeping the difference between the surface temperature and the internal temperature small.

  Next, the curing procedure will be described. FIG. 2 shows an outline of a construction procedure of a concrete structure, and FIG. 3 shows a curing procedure. As shown in Fig. 2, when constructing a concrete structure (especially mass concrete structure), reinforcing bars to be laid inside the structure are arranged, and then a formwork is installed around the inside of the formwork. Place concrete in the wall. The curing process is started immediately after placement, and the curing sheet is removed after the curing is completed to construct a concrete structure.

  Here, as shown in FIG. 3, the curing process is roughly divided into a placement stage curing process and a release stage curing process. The placement stage curing process is a curing process in a state where the mold is installed, and the mold release stage curing process is a curing process after the mold is removed.

  In the placing stage curing process, the concrete surface has a region (side surface) in contact with the mold and a region (upper surface) where the mold does not exist, and is cured by distinguishing these. Therefore, first, the sheet is covered from the upper surface (region where there is no formwork). This is because the wrapping sheet 1 (FIG. 1) is coated on the entire top surface of the concrete, so that the top surface is coated before the side surface. Then, the side surface is coated from the surface of the mold (primary side surface coating) and cured in this state for several days. This is the placement stage curing process. Thereafter, the sheet covering the side surface is once removed, the formwork is detached from the side surface (release), and the side surface is covered again with the sheet (secondary side surface coating). The covering sheet at this time is coated with the same covering sheet as that of the primary side surface covering after the wrapping sheet 1 (FIG. 1) is adhered and coated on the concrete surface. It is cured for several days in this state. This is the mold release stage curing process. When these series of steps are completed, the entire covering sheet is removed and the curing is completed.

  The curing process will be described with reference to the drawings. 4 to 6 are conceptual diagrams of the concrete structure along the curing process. As shown to Fig.4 (a), the formwork Y1-Y4 is installed in the circumference | surroundings which construct a concrete structure, and concrete is laid in the inside. Although illustration is omitted, necessary reinforcing bars are disposed inside the concrete. In this state, the concrete upper surface XA is covered. As shown in FIG. 1A, the sheet to be covered is a first covering sheet 10 in which a wrapping sheet 1, a heat insulating sheet 2, a heat insulating sheet 3 and a light blocking sheet 4 are laminated in this order. As shown in FIG. 4B, the entire surface of the concrete upper surface XA is covered with the first covering sheet 10. Furthermore, as shown to Fig.5 (a), a side surface coat | covers the surface of formwork Y1-Y4 with the 2nd coating sheet 20. FIG. The second cover sheet 20 is formed by laminating the heat shield sheet 2, the heat retaining sheet 3 and the light shield sheet 4 in this order. When the side surface is covered with the covering sheet 20, the periphery of the sheet 10 that covers the upper surface XA (the portion that hangs down) can be laminated inside the covering sheet 20.

  After curing for several days in this state, as shown in FIG. 5B, the side covering sheet 20 is removed, the side molds Y1 to Y4 are exposed, and the molds are removed ( FIG. 6 (a)). At this time, the concrete side surfaces X1 to X4 come into contact with the outside air for the first time. Therefore, the wrapping sheet 1 is brought into close contact with the surface of the side surfaces X1 to X4, and all of the side surfaces X1 to X4 are covered with the wrapping sheet 1, and further, the second covering sheet 20 is superimposed on the first covering. The side surface is covered with the same laminated structure as that of the sheet 10 (FIG. 6B).

  In this way, the entire curing process is completed by allowing the curing period of several days to pass with the entire surface of the concrete covered with the second covering sheet 20. Note that a waterproof sheet may be laminated on the outermost layer for both the first cover sheet 10 and the second cover sheet 20. This waterproof sheet may be laminated on the outermost layer as a standard sheet in all cases, but only a difference in rainy weather may be laminated separately.

  Moreover, although the period which should coat | cover a covering sheet (it requires for curing) is defined by analysis, it is preferable to cover exceeding this period. By covering over the curing period, the state of generation of heat of hydration inside the concrete gradually decreases, the internal temperature decreases, and the internal temperature approaches the surface temperature. A gradual decrease in internal temperature results in a gradual decrease in the temperature of the entire concrete, and can approach the outside air temperature. Then, after the internal temperature is sufficiently lowered (after the generation of heat of hydration has converged), the cover sheet is removed, so that the internal temperature does not increase and the subsequent temperature difference becomes stable.

  Although this embodiment is as above-mentioned, the said embodiment shows an example of this invention and this invention is not limited to these. Therefore, various forms can be made within the scope of the gist of the present invention. Sheets to be covered for curing are a plurality of laminated sheets, which are sequentially covered by these plural sheets. All of them are laminated in advance according to the order, and these are integrated to form a covering sheet. However, the integrated sheet may be collectively covered at one time.

  The various sheets use terms such as wrapping, heat insulation, heat insulation, light shielding and waterproofing to indicate their functions, but if they have such functions, they have other properties. May be. For example, the heat shielding sheet 2 may have a light shielding property, and the light shielding sheet 4 may have a heat shielding effect. And when these two types of sheet | seats 2 and 4 are excellent also about any property, you may comprise with the same material. The same applies to other sheets.

<Experimental example 1>
The internal temperature and the surface temperature of the concrete were measured under curing conditions using a coated sheet in an environment with a daily average temperature of 15 ° C. The used concrete was made into the cube of 1/4 size (length 5.0m, width 3.5m, height 2.0m) of the side wall footing.

  The analysis method was as follows. The temperature analysis was performed by a three-dimensional finite element method (FEM), and analysis software “ASTEA MACS Ver. 9.1.2” manufactured by Computational Mechanics Laboratory Co., Ltd. was used. Various parameters used for the analysis are as shown in Table 1. The outside air temperature was assumed to change by averaging the monthly maximum and minimum temperatures in the same period of the previous year.

  As a result of the above analysis, the internal temperature reached its maximum at the age of 3 days and increased to 60 ° C. The surface temperature rose to 41 ° C. on the second day of material age. The crack index was lowest on the 6th day of age and was about 1.4, but became 1.0 or more at all ages. In addition, it converged to about 2.0 after the 37th day of material age.

  Based on the above analysis results, the concrete was cured and the surface temperature and internal temperature were measured. In addition, about the ages 0-2, it was set as the placement stage curing process, and it was set as the mold release stage curing process after the ages 2 days. The covering sheet was a simple one for experimentation, and the vinyl sheet, the heat shielding sheet and the light shielding sheet were aluminum sheets for the wrapping sheet. A plastic cardboard was used as the heat insulation sheet, and a blue sheet was used as the waterproof sheet. The heat shielding performance, the heat retaining performance and the light shielding performance were assumed to be slightly insufficient, but the effect was sufficient. The result is shown in FIG. In addition, as a comparative example, the temperature change at the time of using the curing method by the conventional method is also shown in the figure. A conventional method is a case where what is sold as a commercial building curing sheet is used.

As shown in FIG. 7, the internal temperature of the concrete is higher than that in the conventional method, and the rate of temperature decrease is moderate, but the surface temperature is much higher than that in the conventional method. It turned out that it is changing. In the case where the difference between the two temperatures was the largest, the temperature reached 24 ° C., but in the conventional method, it reached 38 ° C. In this way, the overall temperature of the concrete is high by promoting the increase in the surface temperature as the internal temperature rises (heat retention of hydration heat), but the difference in temperature between the two becomes small. Therefore, the temperature difference that causes cracks can be eliminated. Actually, the condition of the concrete after curing was visually observed, but no cracks were found.
<Experimental example 2>
As a second experimental example, the curing condition in summer was tested. Experiments were conducted in August and September. The analysis method is the same as that in Table 1 except for the initial temperature (ground and skeleton) and fixed temperature (ground). Each of these temperatures is 25.1 ° C. (initial temperature of the ground), 30.1 ° C. (initial temperature of the enclosure), 11.8 ° C. (fixed temperature) in August, and in September, They were 23.7 ° C. (initial temperature of the ground), 28.7 ° C. (initial temperature of the frame), and 11.8 ° C. (fixed temperature). As a result of the analysis, in the above conditions, the crack index during the curing period was 1.0 or more, and the curing period was 6 days. However, in reality, curing was completed on the age of 8 days, and thereafter, wet curing with only a wrapping sheet was performed for 7 days. The results in these are shown in FIG. FIG. 8A shows the experimental results for August, and FIG. 8B shows the experimental results for September. In addition, since both measured the external temperature and the surface temperature, these are shown simultaneously.

  As is clear from the above results, the surface temperature transition at the analysis temperature was compared with the actually measured value, and the actually measured value was slightly lower, and the surface temperature did not become high despite the summer. Further, the difference between the internal temperature and the surface temperature in the analysis value was about 19 ° C. at the maximum even when both experiments were combined, and a temperature difference that would cause cracking due to temperature stress did not occur. Moreover, although the surface crack state was confirmed visually after wet curing, the surface crack by drying was not discovered.

  As described above, both hot concrete in the summer and cold concrete in the winter can be cured under conditions where the crack index is 1.0 or more without requiring a heater or watering. The above experimental results mean that the surface can be maintained at a sufficiently high temperature without supplying heat from the outside by using only the heat of hydration. Second, since the internal temperature due to the heat of hydration can be maintained at an appropriate temperature, the difference from the surface temperature can be reduced with increasing internal temperature even in summer. Furthermore, thirdly, it is possible to obtain a wetting effect by the wrapping sheet in the summer, and to suppress the generation of vaporization heat accompanying the water supply by the waterproof sheet in the winter. Therefore, according to the curing method of the present invention, the temperature difference between the inside and the surface can be reduced both in summer and in winter. The fact that cracking can be avoided by the same curing method regardless of the difference in the temperature of the outside temperature means that concrete that is stable by the same method in all climatic conditions without distinguishing between cold concrete and hot concrete. Can be cured. In other words, it is possible to provide high-quality and solid concrete structures throughout the year.

DESCRIPTION OF SYMBOLS 1 Lapping sheet 2 Heat insulation sheet 3 Heat insulation sheet 4 Light shielding sheet 5 Waterproof sheet 10 1st coating sheet 20 2nd coating sheet X Concrete surface XA Concrete upper surface X1, X2, X3, X4 Concrete side surface Y, Y1, Y2, Y3 , Y4 formwork

Claims (8)

A laminate more heat transfer coefficient in the heat sheet and heat insulating sheet barrier is 3.8W / m ² ° C. or less, thereby coating the surface of the concrete to be cured while the thermal barrier sheet on the inside, further laminate A concrete curing method for covering the surface of the sheet with a light shielding sheet ,
While performing the initial temperature of the ground and the skeleton and the fixed temperature of the ground, and performing the temperature analysis during curing with the laminated body under the condition that the heat transfer coefficient of the laminated body is 3.8 W / m ² ° C or less, The heat transfer rate and curing period are set in advance so that the crack index values calculated with reference to the temperature difference between the internal temperature and the surface temperature of the concrete based on the temperature analysis are all 1.0 or more during the curing period. ,
A concrete all-weather curing method characterized in that, during a set curing period, the concrete surface is covered with a laminate having a set heat transfer coefficient, and further, the surface of the laminate is covered with a light shielding sheet . Covering the surface of the concrete to be cured, with the heat shield sheet and the heat insulating sheet, and the laminated body constituted within the range of 3.3 to 3.8 W / m ² ° C. with the heat shield sheet inside. In addition, a concrete curing method for covering the surface of the laminate with a light shielding sheet,
When curing with the laminate according to the conditions that the initial temperature of the ground and the skeleton and the fixed temperature of the ground are used, and the heat transfer coefficient of the laminate is within the range of 3.3 to 3.8 W / m ² ° C. The heat transfer coefficient at which all the values during the curing period of the crack index calculated with reference to the temperature difference between the internal temperature and the surface temperature of the concrete based on the temperature analysis are 1.0 or more and Set the curing period in advance ,
During the set curing period, set by Do that product Sotai the heat transfer coefficient as well as covering the concrete surface, further all-weather concrete, which comprises coating the surface light-shielding sheet of the laminate cured Method.   3. The concrete all-weather curing method according to claim 2, wherein the curing period is a period in which a temperature drop at the end of curing is 17 ° C. or less based on the analysis temperature.   The concrete all-weather curing method according to any one of claims 1 to 3, wherein a wrapping sheet is laminated on the inside of the laminate on a surface of the concrete to be cured that is not protected by a formwork.   5. The concrete all-weather curing method according to any one of claims 1 to 4, wherein the surface of the light-shielding sheet is covered with a waterproof sheet to block water supply to the cast concrete. Covering the surface of the concrete to be cured with the heat shield sheet and the heat insulating sheet having a heat transfer coefficient in the range of 3.3 to 3.8 W / m ² ° C. with the heat shield sheet inside. In addition, a concrete curing method for covering the surface of the laminate with a light shielding sheet ,
During curing with the laminate according to the conditions that the initial temperature of the ground and the skeleton and the fixed temperature of the ground are used, and the heat transfer coefficient of the laminate is within the range of 3.3 to 3.8 W / m ² ° C. The heat transfer coefficient at which all the values during the curing period of the crack index calculated with reference to the temperature difference between the internal temperature and the surface temperature of the concrete based on the temperature analysis are 1.0 or more and Set the curing period in advance ,
The curing process during the set curing period includes a placement stage curing process and a release stage curing process,
In the placing step curing process, on the side of the concrete where the placed concrete is dammed by the mold, the surface of the mold is covered with a laminate with a set heat transfer coefficient , and the surface is covered with a light shielding sheet. Covering and placing the wrapping sheet on the top surface of the placed concrete, and covering with a laminate with a set heat transfer coefficient , and further covering the surface with a light shielding sheet,
The mold release stage curing process is a laminated body with a set heat transfer coefficient after closely attaching a wrapping sheet to each surface on each of the concrete side surface after removing the formwork and the top surface of the cast concrete. An all-weather curing method for concrete, characterized in that it is coated and the surface is covered with a light-shielding sheet.   7. The concrete according to claim 6, wherein in either or both of the placing stage curing process and the release stage curing process, at least an upper surface of the concrete is further coated with a waterproof sheet on a surface of the light shielding sheet. All-weather curing method.   The concrete all-weather curing method according to claim 6 or 7, further comprising a wrapping step of covering the concrete surface only with a wrapping sheet after the curing step.

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