Prediction method for drying shrinkage strain and drying shrinkage stress of concrete

Abstract

To provide a method for predicting drying shrinkage strain of concrete by using a drying shrinkage prediction formula that includes time (age of concrete) as a parameter.SOLUTION: A method for predicting drying shrinkage strain of concrete is provided by including at least (A) a humidity analysis process, (B) a process for deriving a first regression equation (the following equation (1)), (C) a process for deriving a second regression equation (the following equation (2)), and (D) a process for calculating a predicted value of the drying shrinkage strain. εRH_te / ε60_te=(96-RH) / {c×(96-RH)+d}...(1) ε60_te / ε60_7=-a×(te)1 / 2+b... (2) (where εRH_te / ε60_te represents a ratio of an ultimate value (εRH_te) of drying shrinkage strain at each of three or more kinds of relative humidity at respective positions to an ultimate value (ε60_te) of drying shrinkage strain at reference relative humidity (60%), RH represents relative humidity (%), c and d represent coefficients, etc.).SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a method for predicting drying shrinkage strain of concrete using a drying shrinkage prediction formula that includes time (age of concrete) as a parameter. [Background technology]

[0002] Concrete has low tensile strength, so shrinkage cracks can occur due to shrinkage of the concrete. These shrinkage cracks not only ruin the aesthetic appearance of concrete structures, but also reduce the durability of concrete structures by reducing the watertightness and airtightness of the concrete and corroding rebar. Therefore, controlling shrinkage cracks is necessary to maintain the durability of concrete. The main cause of shrinkage cracks is the drying shrinkage strain of concrete, which is strain caused by external and internal constraints on concrete, as shown in Figure 1. Therefore, in order to control shrinkage cracks in concrete, it is important to understand this drying shrinkage strain in advance.

[0003] Conventionally, there are two types of prediction formulas for drying shrinkage strain of concrete: one proposed by the Architectural Institute of Japan (hereinafter referred to as "Architectural Institute of Japan formula") and one proposed by the Japan Society of Civil Engineers (hereinafter referred to as "JSCE formula"). Of these, the Architectural Institute of Japan formula is the following prediction formula, which multiplies an equation including parameters such as the relative humidity around the concrete, the volume of the concrete, the surface area in contact with the outside air, and the volume-surface area ratio by an equation including a correction coefficient that represents the influence of the type of cement, etc. (Non-Patent Document 1, pages 4, 5, and 182).

[0004] TIFF2025139134000002.tif52159

[0005] The Japan Society of Civil Engineers formula is the following prediction formula that includes the same parameters as the Architectural Institute of Japan formula (page 46 of Non-Patent Document 2).

[0006] TIFF2025139134000003.tif60156

[0007] However, as shown in Figure 2, the relative humidity inside concrete is not constant and is higher the closer to the center of the concrete. Therefore, conventional prediction methods that use the relative humidity (constant value) around the concrete as a parameter for the relative humidity in the prediction formula do not reflect the distribution of relative humidity inside the concrete, and only provide a single predicted value for drying shrinkage strain for the entire cross section of the concrete, as shown in the comparative example in Figure 3 (reprinted from Figure 12 of Patent Document 2) using the Japan Society of Civil Engineers formula. Furthermore, when predicting drying shrinkage stress, only external constraints are evaluated, and internal constraints are not taken into account, resulting in low prediction accuracy, as shown in the comparative example in Figure 4 (reprinted from Figure 13 of Patent Document 2).

[0008] In response to this situation, the present inventor created the invention described in Patent Document 1, which enabled highly accurate prediction. However, this invention had the problem that because the ultimate value of drying shrinkage strain was measured in accordance with Annex A (reference) of JIS A 1129, it took a long time to obtain the ultimate value of drying shrinkage strain, and it took a long time to predict the drying shrinkage strain and drying shrinkage stress of concrete.

[0009] Therefore, according to the invention described in Patent Document 2, which was created by the present inventor, (i) By using a specific drying shrinkage strain measuring device that uses a laser, the ultimate value of the drying shrinkage strain of a concrete specimen can be measured accurately in a short period of time, (ii) By using a specific prediction formula (single formula) that shows the relationship between the ratio of the ultimate value of the drying shrinkage strain and the relative humidity, it has become possible to accurately predict the drying shrinkage strain and drying shrinkage stress of concrete, even if the cement, aggregate, etc. are different.

[0010] As described above, the prediction accuracy of drying shrinkage strain has been significantly improved by the prediction formulas described in Patent Documents 1 and 2. However, with conventional prediction formulas, including these formulas, the relationship (formula) between relative humidity and shrinkage strain remains unchanged regardless of the drying period, i.e., whether immediately after drying or after one year of drying. However, if we consider the changes in the pore structure in concrete over time due to drying and hydration, the relationship between relative humidity and shrinkage strain is likely to change naturally over time. Therefore, if there is an equation that includes time as a parameter and can handle the above-mentioned changes in concrete over time, we can expect the accuracy of predicting drying shrinkage strain to be further improved. [Prior art documents] [Non-patent literature]

[0011] [Non-Patent Document 1] "Guidelines for Design and Construction of Reinforced Concrete Buildings to Control Shrinkage Cracking (Draft) and Commentary," compiled by the Architectural Institute of Japan, published in February 2006. [Non-patent document 2] "2007 Concrete Standard Specifications [Design Edition]", edited by the Japan Society of Civil Engineers, published in March 2008 [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-221779 [Patent Document 2] Japanese Patent Application Publication No. 2019-7842 Summary of the Invention [Problem to be solved by the invention]

[0013] Based on the above technical concept, the present invention aims to provide a method for predicting drying shrinkage strain of concrete using a drying shrinkage prediction formula that includes time (age of concrete) as a parameter. [Means for solving the problem]

[0014] The inventors have investigated prediction methods that meet the above-mentioned objectives, and based on the new finding that the drying shrinkage of concrete decreases as the age at the start of drying (te) of concrete increases, they have derived the following formula (2). They have also found that the prediction accuracy of drying shrinkage strain can be further improved by using formula (2) in combination with formula (1) described in Patent Document 2, and have completed the inventions [1] to [3] below. Here, the drying start age (te) is the period from the time the concrete is poured until the concrete is demolded. The drying start age is evaluated at the effective age, and is the age calculated by converting the effect of curing temperature on the hydration reaction to the degree of hydration when the curing temperature is 20°C.

[0015] [1] A method for predicting drying shrinkage strain of concrete, which includes at least the following steps (A) to (D): (A) Humidity analysis process: determining the relative humidity at each location from the concrete surface to the center (B) The ultimate value of drying shrinkage strain (ε RH_te ), and the ultimate value of drying shrinkage strain at the reference relative humidity (60%) (ε 60_te ) ratio (ε RH_te / ε 60_te )and, Using the relative humidity (RH) at each of the above locations, A process of deriving a first regression equation by calculating coefficients c and d by regression analysis based on the following equation (1) ε RH_te / ε 60_te =(96-RH) / {c×(96-RH)+d} ···(1) (However, in equation (1), ε RH_te / ε 60_te is the ultimate value of drying shrinkage strain (ε RH_te ), and the ultimate value of drying shrinkage strain at the reference relative humidity (60%) (ε 60_te ) where RH represents relative humidity (%) and c and d represent coefficients. (C) Ultimate value of drying shrinkage strain at standard relative humidity (ε 60_te), and the ultimate value of drying shrinkage strain at the start of drying at 7 days old at the standard relative humidity (ε 60_7 ) ratio (ε 60_te / ε 60_7 )and, Using the drying start age (te), The process of deriving the second regression equation by calculating coefficients a and b through regression analysis based on the following equation (2): ε 60_te / ε 60_7 =-a×(te) 1 / 2 +b (2) (However, in equation (2), ε 60_te / ε 60_7 is the ultimate value of drying shrinkage strain at the reference relative humidity (ε 60_te ), and the ultimate value of drying shrinkage strain at the start of drying at 7 days old at the standard relative humidity (ε 60_7 ) where te represents the age of the wood at the start of drying (days), and a and b represent coefficients. (D) The second regression equation derived in the above (C) process, and the ultimate value of drying shrinkage strain at the start of drying at 7 days old at the measured or known reference relative humidity (ε 60_7 ) to calculate the ultimate value of drying shrinkage strain (ε 60_te ) is calculated, Furthermore, the first regression equation, the relative humidity (RH) at each position in the concrete, and the ultimate value of the drying shrinkage strain (ε 60_te ) and the predicted value of drying shrinkage strain (ε RH_te ) and the process of calculating the predicted value of drying shrinkage strain [2] A method for predicting drying shrinkage strain of concrete, including the following processes (a) and (b). (a) Ultimate value of drying shrinkage strain at 7 days of drying start at standard relative humidity (ε 60_7 ) and the following equations (3) to (5), the ultimate value of drying shrinkage strain at the standard relative humidity (ε 60_te ) calculation process (where a and b are constants, with a = 0.0170 and b = 1.0898 for ordinary Portland cement and a = 0.0093 and b = 1.0493 for moderate-heat Portland cement.) TIFF2025139134000004.tif26155(b) Ultimate value of drying shrinkage strain at standard relative humidity (ε 60_te ) and the final value of drying shrinkage strain (ε RH_te ) calculation process ε RH_te =((96-RH) / (c ×(96-RH)+ d))×ε 60_te ···(6) (where c and d are constants, with c = 0.63 and d = 13.26 for ordinary Portland cement and c = 0.50 and d = 18.00 for moderate-heat Portland cement.) [3] A method for predicting the drying shrinkage stress of concrete, further comprising calculating a predicted value of the drying shrinkage stress at each position from the predicted value of the drying shrinkage strain of the concrete at each position described in [1] or [2] above by stress analysis. [Effects of the Invention]

[0016] The prediction method of the present invention takes into account time (the age of the concrete) and the moisture distribution inside the concrete, making it possible to accurately predict drying shrinkage strain and drying shrinkage stress along the cross section of the concrete in a short period of time. This makes it possible to easily predict with high accuracy the possibility of cracks occurring when determining or evaluating shrinkage cracks in concrete. [Brief explanation of the drawings]

[0017] [Figure 1] This is a conceptual diagram showing the drying shrinkage strain and drying shrinkage stress of concrete caused by internal and external restraints. [Figure 2] This is a diagram showing the change over time in predicted values ​​of relative humidity at various positions from the surface of a concrete wall, and is a reprint of Figure 9 in Patent Document 2. [Figure 3] This is a diagram showing the change over time in predicted values ​​of drying shrinkage strain at various positions from the surface of a concrete wall, and is a reprint of Figure 12 from Patent Document 2. [Figure 4]This is a diagram showing the change over time in predicted values ​​of drying shrinkage stress at various positions from the surface of a concrete wall, and is a reprint of Figure 13 from Patent Document 2. [Figure 5] This is a schematic diagram showing an example of a drying shrinkage strain measuring device in which a concrete specimen is placed on a drying shrinkage strain measuring device that is configured so that the lasers emitted from the laser displacement meters intersect at an angle of 90°. [Figure 6] This figure shows the change over time in drying shrinkage of concrete specimens (using ordinary Portland cement) at a relative humidity of 33%, measured using a drying shrinkage measuring device, with the starting drying ages varied to 7, 28, 91, 182, 365, and 728 days. [Figure 7] This is a plot of drying shrinkage strain at each age and relative humidity, with the black squares representing the average value of drying shrinkage strain at each relative humidity. [Figure 8] This figure shows the regression curve obtained by performing regression analysis using equation (1) based on the ratio of relative humidity to drying shrinkage strain, and the fitting of the plot of the ratio of relative humidity to drying shrinkage strain (εRH_te / ε60_te). [Figure 9] This figure shows the fitting of the connected straight lines drawn using equations (3) to (5) to the plot of time ((te)1 / 2) and the ratio of drying shrinkage strain (ε60_te / ε60_7). [Figure 10] FIG. 1 shows curves drawn using the formula of the present invention (formula (1) + formula (2)) and the conventional formula (formula (1) only), and fitting of plots of drying period and drying shrinkage strain at a position 10 mm from the concrete surface. [Figure 11] FIG. 1 shows the fitting of curves drawn using the formula of the present invention (formula (1) + formula (2)) and the conventional formula (formula (1) only) and plots of drying period and drying shrinkage strain at a position 25 mm from the concrete surface. [Figure 12]FIG. 1 shows curves drawn using the formula of the present invention (formula (1) + formula (2)) and the conventional formula (formula (1) only), and fitting of plots of drying period and drying shrinkage strain at a position 50 mm from the concrete surface. DETAILED DESCRIPTION OF THE INVENTION

[0018] As described above, the present invention provides a method for predicting the drying shrinkage strain of concrete, which includes at least (A) a humidity analysis process, (B) a process for deriving a first regression equation, (C) a process for deriving a second regression equation, and (D) a process for calculating a predicted value of the drying shrinkage strain, and a method for predicting the drying shrinkage stress of concrete by calculating a predicted value of the drying shrinkage stress at each position in the concrete from the predicted value through stress analysis. The present invention will be described in detail below, dividing it into a method for predicting drying shrinkage strain and a method for predicting drying shrinkage stress.

[0019] 1. Method for predicting drying shrinkage strain (A) Humidity analysis process This process involves using moisture analysis software to analyze the relative humidity from the surface to the center of the concrete and its changes over time. Examples of such software include "ASTEA MACS" (manufactured by Computational Mechanics Research Center) and "JCMAC3" (sold by the Japan Concrete Institute), which are equipped with a three-dimensional moisture transport analysis function. An example of the relative humidity distribution inside concrete determined using "ASTEA MACS" is shown in Figure 2.

[0020] (B) Derivation process of the first regression equation This process involves measuring the ultimate values ​​of drying shrinkage strain (ε RH_te , the value at which the drying shrinkage strain becomes constant or nearly constant), and the ultimate value of the drying shrinkage strain at the reference relative humidity (60%) (ε 60_te ) ratio (ε RH_te / ε 60_te) and the relative humidity (RH) at each of the above positions, coefficients c and d are calculated by regression analysis based on the following equation (1) to derive the regression equation. ε RH_te / ε 60_te =(96-RH) / {c×(96-RH)+d} ···(1) (However, in equation (1), ε RH_te / ε 60_te is the ultimate value of drying shrinkage strain (ε RH_te ), and the ultimate value of drying shrinkage strain at the reference relative humidity (60%) (ε 60_te ) where RH represents relative humidity (%) and c and d represent coefficients.

[0021] The reference relative humidity was set to 60% for the following reasons. (i) Measurement of drying shrinkage strain of concrete at a relative humidity of 60% is specified in Appendix A (reference) of the above-mentioned JIS A 1129. (ii) "Guidelines for Design and Construction of Reinforced Concrete Buildings for Shrinkage Crack Control (Draft) and Commentary" (published by the Architectural Institute of Japan), "Standard Specifications for Building Construction and Commentary" JASS5 (published by the Architectural Institute of Japan), and "Standard Specifications for Concrete" (published by the Japan Society of Civil Engineers) state that drying shrinkage strain should be measured in accordance with the above JIS regulations. As a result of the widespread use of measuring drying shrinkage strain at a relative humidity of 60%, a huge amount of data on drying shrinkage strain at a relative humidity of 60% has been accumulated for many types of concrete. (iii) The above ratio (ε RH_te / ε 60_te ) is used, the ultimate value of drying shrinkage strain at a relative humidity of 60% (ε 60_te ) from the existing data, the predicted value of drying shrinkage strain (ε RH_te ) can be easily calculated, so existing data can be used effectively. Therefore, drying shrinkage strain can be accurately predicted using existing data without newly measuring drying shrinkage strain at a relative humidity of 60%. However, to further improve prediction accuracy, it is also possible to actually measure the ultimate value of drying shrinkage strain at a relative humidity of 60% using a test specimen with the same composition as the concrete to be predicted, and use this measured value instead of the existing data.

[0022] (C) Derivation process of the second regression equation The process involves determining the ultimate value of drying shrinkage strain (ε 60_te ), and the ultimate value of drying shrinkage strain at the start of drying at 7 days old at the standard relative humidity (ε 60_7 ) ratio (ε 60_te / ε 60_7 ) and the age at the start of drying (te), coefficients a and b are calculated by regression analysis based on the following equation (2) to derive the regression equation. ε 60_te / ε 60_7 =-a×(te) 1 / 2 +b (2) (However, in equation (2), ε 60_te / ε 60_7 is the ultimate value of drying shrinkage strain at the reference relative humidity (ε 60_te ), and the ultimate value of drying shrinkage strain at the start of drying at 7 days old at the standard relative humidity (ε 60_7 ) where te represents the age of the wood at the start of drying (days), and a and b represent coefficients.

[0023] (D) Calculation process for predicted drying shrinkage strain Using the second regression equation derived in the above (C) process, the ultimate value of drying shrinkage strain (ε 60_te ) is calculated, and then the first regression equation, the relative humidity (RH) at each position in the concrete, and the ultimate value of the drying shrinkage strain (ε 60_te ) and the predicted value of drying shrinkage strain (ε RH_te ) is the process of calculating

[0024] 2. Method for predicting drying shrinkage stress This method uses stress analysis software to calculate the predicted drying shrinkage stress at each location in the concrete and its change over time from the predicted drying shrinkage strain at each location. The software can be, for example, the above-mentioned "ASTEA MACS" or "JCMAC3," which also have a three-dimensional stress analysis function. An example of the change over time in the predicted drying shrinkage stress at each location from the surface of a concrete wall is shown in Figure 4. [Example]

[0025] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. 1. Materials used and concrete mix The materials used and the concrete mix are shown in Tables 1 and 2, respectively.

[0026] [Table 1]

[0027] [Table 2]

[0028] 2. Preparation of concrete specimens for drying shrinkage strain measurement The materials shown in Table 1 were charged into a 50-liter pan mixer and mixed for 2 minutes according to the mix proportions N, EX, SRA, and M shown in Table 2. The mixture was then poured into a formwork with an inner diameter of 10 cm and a height of 20 cm. The concrete was then sealed and cured at 20°C for drying start ages of 7, 28, 91, 182, 364, and 728 days, after which it was demolded. Furthermore, the cured concrete was cut near the center in the height direction to prepare three concrete specimens (hereinafter referred to as "specimens") for measuring drying shrinkage strain, each 100 mm in diameter and 10 mm in thickness.

[0029] 3. Drying shrinkage strain (ε) at various relative humidity and starting age RH_te and ε 60_te) measurement Test specimens of each of the above mix proportions were dried at a temperature of 20°C under conditions of relative humidity (RH) of 11%, 33%, 45%, 60%, 75%, and 85%, respectively. During each drying period shown in Figure 6 (an example of concrete using ordinary Portland cement with a relative humidity of 33%), the test specimen was placed on the drying shrinkage strain measurement device shown in Figure 5 so that the peripheral side of the test specimen was in contact with the pins (test specimen positioning jig) of the device, and the distance between the laser displacement gauges and the peripheral side of the test specimen was measured using four laser displacement gauges. In this example, the distance between the laser displacement meter and the surrounding side of each specimen was measured at three locations, and the average value of these distances was calculated as the drying shrinkage of the specimen. Furthermore, the drying shrinkage of the three specimens (average values) was further averaged to calculate the drying shrinkage (ε RH_te ) was calculated. Figure 6 shows the change in drying shrinkage strain over time at the various relative humidities mentioned above. As shown in Figure 6, when the drying shrinkage strain measuring device shown in Figure 5 is used, the final value of drying shrinkage strain can be obtained as early as within 50 days of the drying period.

[0030] 4. Regression analysis using equation (1) The following explanation will be given using concrete of mix N using ordinary Portland cement as an example. First, the drying shrinkage strain (ε RH_te ) are shown in Table 3 and Figure 7.

[0031] [Table 3]

[0032] In addition, drying shrinkage strain (ε RH_te ) and drying shrinkage strain (ε 60_te ) ratio (ε RH_te / ε 60_te(hereinafter referred to as "drying shrinkage ratio"; however, in Figure 8 it is written as "drying shrinkage ratio"). Figure 8 shows a graph plotting the relationship between relative humidity and drying shrinkage ratio. Furthermore, based on the relative humidity and drying shrinkage strain ratio, regression analysis (fitting) was performed using equation (1) to determine the coefficients c and d of equation (1), leading to the following equation (1'). Figure 8 shows the curve drawn by equation (1'). The curve and the plot match, as shown in Figure 8. ε RH_te / ε 60_te =(96-RH) / {0.63×(96-RH)+13.26} ···(1´)

[0033] The coefficients c and d in equation (1) were determined for the concretes with mixes EX, SRA, and M shown in Table 2 in the same manner as for the concrete with mix N. The results are shown in Table 5.

[0034] [Table 4]

[0035] 5. Regression analysis using equation (2) Drying shrinkage strain (ε 60_te ) and drying shrinkage strain (ε 60_7 , -841) drying shrinkage strain ratio (ε 60_te / ε 60_7 ), and the age at the start of drying of the specimen (te), a regression analysis was performed using equation (2) to determine the coefficients a and b of equation (2), and the following equation (2') was derived. Figure 9 shows the connected straight line drawn by equation (2') below. As shown in Figure 9, the straight line and the plot match.

[0036] [Table 5]

[0037] 6. Prediction of drying shrinkage strain ε in the above equation (2') 60_7The drying shrinkage strain (ε 60_te ) are shown in Table 6. In addition, to confirm the accuracy of the prediction, the drying shrinkage strain (ε 60_te ) experimental values ​​are shown in Table 7.

[0038] [Table 6]

[0039] [Table 7]

[0040] The drying shrinkage strain (numerical values) corresponding to Tables 6 and 7 are all almost the same. Therefore, it can be seen that by using a combination of Equations (1´) and (2´), the drying shrinkage strain of concrete can be predicted (calculated) with high accuracy.

[0041] 5. Prediction of drying shrinkage strain at each position inside concrete A 100 mm thick cylindrical specimen made using concrete of mix N was dried at 20°C and a relative humidity of 33% with the sides sealed and both end faces left open (open). Next, the relative humidity and drying shrinkage were measured at positions 10 mm, 25 mm, and 50 mm from the drying surface during the drying period shown in Table 8. The relative humidity is shown in Table 8, and the drying shrinkage is shown in Table 9.

[0042] [Table 8]

[0043] [Table 9]

[0044] Next, the drying shrinkage strain was predicted (calculated) using the above formulas (1') and (2') based on the relative humidity in Table 8. The results are shown in Table 10. For comparison, drying shrinkage strain was predicted (calculated) using the above formula (1') based on the invention described in Patent Document 2. The results are shown in Table 11.

[0045] [Table 10]

[0046] [Table 11]

[0047] Furthermore, based on the values ​​in Tables 9 to 11, the drying shrinkage strain was plotted at positions 10 mm, 25 mm, and 50 mm from the drying surface, and is shown in Figures 10 to 12, respectively. As shown in FIGS. 10 to 12, it can be seen that the prediction method of the present invention can predict values ​​that are much closer to experimental values ​​than the prediction method described in Patent Document 2 (the method using formula (1)).

Claims

1. A method for predicting drying shrinkage strain of concrete, comprising at least the following steps (A) to (D): (A) The humidity analysis process, which determines the relative humidity at each position from the surface to the center of the concrete. (B) The ultimate value of drying shrinkage strain (ε ＲＨ_ｔｅ ), and the ultimate value of drying shrinkage strain at the reference relative humidity (60%) (ε ６０_ｔｅ ) ratio (ε ＲＨ_ｔｅ / ε ６０_ｔｅ )and, Using the relative humidity (RH) at each position, A process of deriving a first regression equation by calculating coefficients c and d by regression analysis based on the following equation (1) to derive a regression equation: e ＲＨ_ｔｅ / e ６０_ｔｅ =(96-RH) / {c×(96-RH)+d} ・・・(1) (where, in equation (1), ε ＲＨ_ｔｅ / ε ６０_ｔｅ is the ultimate value of drying shrinkage strain at each of three or more relative humidity positions (ε ＲＨ_ｔｅ ), and the ultimate value of drying shrinkage strain at the reference relative humidity (60%) (ε ６０_ｔｅ ) where RH represents relative humidity (%), and c and d represent coefficients. (C) Ultimate value of drying shrinkage strain at standard relative humidity (ε ６０_ｔｅ ), and the ultimate value of drying shrinkage strain at the start of drying at 7 days old at the standard relative humidity (ε ６０_７ ) ratio (ε ６０_ｔｅ / ε ６０_７ )and, Using the drying start age (te), A process of deriving a second regression equation by calculating coefficients a and b by regression analysis based on the following equation (2) e ６０_ｔｅ / e ６０_７ =-OO×(t) １／２ +b・・・(2) (However, in equation (2), ε ６０_ｔｅ / ε ６０_７ is the ultimate value of drying shrinkage strain at the reference relative humidity (ε ６０_ｔｅ ), and the ultimate value of drying shrinkage strain at the start of drying at 7 days old at the standard relative humidity (ε ６０_７ ) where te represents the age at the start of drying (days), and a and b represent coefficients. (D) Using the second regression equation derived in the above (C) process, the ultimate value of drying shrinkage strain (ε ６０_ｔｅ ) is calculated, Furthermore, the first regression equation, the relative humidity (RH) at each position in the concrete, and the ultimate value of the drying shrinkage strain (ε ６０_ｔｅ ) and the predicted value of drying shrinkage strain (ε ＲＨ_ｔｅ ) and the process of calculating the predicted value of drying shrinkage strain

2. A method for predicting drying shrinkage strain of concrete, comprising the following steps (a) and (b): (a) The ultimate value of drying shrinkage strain at the start of drying at the standard relative humidity of 7 days (ε ６０_７ ) and the following equations (3) to (5), the ultimate value of drying shrinkage strain at the standard relative humidity (ε ６０_ｔｅ ) calculation process (where a and b are constants, with a = 0.0170 and b = 1.0898 for ordinary Portland cement and a = 0.0093 and b = 1.0493 for moderate-heat Portland cement.) (b) Ultimate value of drying shrinkage strain at standard relative humidity (ε ６０_ｔｅ ) using the following equation (6), the ultimate value of drying shrinkage strain (ε ＲＨ_ｔｅ ) calculation process e ＲＨ_ｔｅ = (96-RH)(c × (96-RH)+ d))×e ６０_ｔｅ ・・・(6) (where c and d are constants, with c = 0.63 and d = 13.26 for ordinary Portland cement and c = 0.50 and d = 18.00 for moderate-heat Portland cement.)

3. 3. A method for predicting drying shrinkage stress of concrete, further comprising: calculating a predicted value of drying shrinkage stress at each position by stress analysis from the predicted value of drying shrinkage strain of concrete at each position according to claim 1 or 2.

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