JP2014020866A - Method for early estimating concrete drying shrinkage strain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of early estimating concrete drying shrinkage strain for highly accurately and early determining the drying shrinkage strain of concrete in an arbitrary long-term material age from the measured value of the drying shrinkage strain in a short-term material age of concrete.SOLUTION: A method of early estimating concrete drying shrinkage strain includes early determining the drying shrinkage strain of concrete in an arbitrary long-term material age by using a relational expression between the measured value of drying shrinkage strain on the 28th day in a drying period at predetermined temperature 80°C and a final drying shrinkage strain value at temperature 20°C or a relational expression obtained by approximating a relation between the final drying shrinkage strain value at temperature 80°C and the final drying shrinkage strain value at temperature 20°C by a primary expression.

Description

  The present invention relates to an early evaluation method of concrete drying shrinkage strain, and in particular, to control cracks caused by concrete shrinkage, the rate of change in length due to drying shrinkage of concrete over a long period of time (hereinafter referred to as “drying shrinkage strain”). It is related with the early evaluation method of the concrete drying shrinkage distortion | strain which can be determined with high precision at an early stage by concrete of short-term age.

As concrete dries, its volume decreases, and this phenomenon is called drying shrinkage. When drying shrinkage is applied to a concrete structure, it causes cracking, so that drying shrinkage strain is regulated.
Shrinkage cracking due to drying shrinkage of concrete is one of the factors that greatly affect the decline in functionality and durability depending on the structure type of buildings and civil engineering structures, and the social demand for its control is increasing year by year. .

For example, in the concrete standard specifications of the Japan Society of Civil Engineers, the drying shrinkage strain of concrete to be considered in the design is indicated as 1200 × 10 ⁻⁶ . In other words, concrete with a drying shrinkage strain of 1200 × 10 ⁻⁶ or more is actually difficult to apply without taking any measures to the structure where shrinkage is a problem. It recommends a flow to calculate the response value of the structure based on the strain and find a solution that passes the verification. On the other hand, JASS5 of the Architectural Institute of Japan defines the drying shrinkage strain of concrete according to the period of service, the long-term service class of about 100 years as the planned service period, and the ultra-long service of about 200 years as the planned service period In the class, it is 8 × 10 ⁻⁴ or less.

However, the drying shrinkage strain is developed over a long period of time, and it takes several years to complete the numerical value.
Therefore, in order to control the drying shrinkage strain of this concrete, it is important to estimate and predict the drying shrinkage strain that progresses over the long-term age, but in reality it is necessary to confirm long-term measurement data. Is a difficult situation.

In the length change test (JIS A 1129-2 Annex A) for measuring the drying shrinkage rate (dry shrinkage strain) of concrete, it is generally dried after being cured under water until the age of 7 days (182). Day) period is required.
In general concrete construction, it is difficult to confirm the quality of concrete more than six months ago, and it is not practical to apply the above test as it is for concrete construction.
For this reason, in order to estimate the drying shrinkage strain in the long-term age from the drying shrinkage data of the concrete obtained in a short period, various estimation formulas have been proposed, and the judgment for regulating the drying shrinkage strain is Estimates based on short-term data are being used.

  According to the Architectural Institute of Japan “Restriction Cracking Control Design and Construction Guidelines (Draft) of Reinforced Concrete Buildings” (Non-Patent Document 1) and the Japan Society of Civil Engineers “Standard Specification for Concrete” (Non-Patent Document 2) Due to the characteristic of asymptotically approaching the final value over a long period of time, it is estimated by approximating with functional expressions such as the following expressions (1) and (2).

Here, in the above formula, ε _sh (t, t ₀ ) is the drying shrinkage strain (× 10 ⁻⁶ ) from the material age t ₀ day (drying start date) to the material age t day, and ε _sh∞ is the final drying shrinkage strain. Values (× 10 ⁻⁶ ), α, β, γ, and δ are coefficients representing the degree of progress of drying.

For example, as in Equation (1) ', the age _{t 0} days specific measurement data of drying shrinkage strain from (dry start date) at an arbitrary short ages _{t e} date of concrete (epsilon _{sh (t} e, _{t 0} ) ₂₀ (× substituting ^{10 -6)),} final drying shrinkage strain values by obtaining _(ε sh∞), drying shrinkage strain of long ages _{t L} from equation _{(1) (ε sh (t} L, t ₀ ) (× 10 ⁻⁶ )).
In addition, according to the length change test prescribed | regulated to JIS A 1129-2 appendix A which measures the drying shrinkage | contraction strain of concrete, the regulation value of a drying shrinkage strain | stamp is normally 6 months old.

The above formula (1) is the Architectural Institute of Japan “Shrinkage Crack Control Design and Construction Guidelines (Draft) of Reinforced Concrete Buildings” (Non-Patent Document 1), and the above Formula (2) is the Japan Society of Civil Engineers “Concrete Standard Specification” (Non-patent) Reference 2) is adopted, and both of the above formulas are based on enormous data on drying shrinkage strain, and α = 0.16 (V / S) ^1.8 (V is the volume of the concrete specimen (mm ^3). ), S is defined as the surface area (mm ² ) of the specimen, and in the length change test for measuring the drying shrinkage strain defined in JIS standard (for example, JIS A 1129-2 Annex A), V / Since S = 22.2 mm, α = 42.5), β = 1.4 (V / S) ^−0.18 (β = 0.8), γ = 0.108, δ = 0.56 It stipulates.

The Architectural Institute of Japan “Construction Cracking Control Design and Construction Guidelines (Draft) of Reinforced Concrete Buildings” (Non-patent Document 1) and “Concrete Standard Specification” (Non-patent Document 2) of Japan Society of Civil Engineers By defining the experimental constant of equation (2), the operation of the estimation equation for drying shrinkage strain is enhanced, but on the other hand, the drying period is relatively short (for example, concrete from the age of 7 days corresponding to the drying start date). There is a problem that the estimated value of the drying shrinkage strain at the age of 6 months obtained from the measured data in the drying period of 28 days until the age of 35 days is inaccurate, and the measured value of the drying shrinkage strain after the age of 6 months. May be 100 to 200 (× 10 ⁻⁶ ).
Since the regulation value of the drying shrinkage strain according to the Architectural Institute of Japan “Building Construction Standard Specification (JASS5)” is 8 (× 10 ⁻⁴ ), it is 100 to 200 (× 10 ⁻⁶ ) as the difference from the measured value. The error is a numerical value that cannot be ignored.

  In addition, Imamoto et al. “A Study on Prediction of Drying Shrinkage Strain of Concrete Based on Short-term Data” (The Architectural Institute of Japan, No. 602, pp. 15-20, 2006. 4) (Non-Patent Document 3) In the same way as the above guideline, a method is proposed in which the drying shrinkage strain of concrete can be approximated by a specific prediction formula, and the final drying shrinkage strain is estimated by sequentially using all the short-term data.

  In Japanese Patent Application Laid-Open No. 2008-8753, as an early estimation method of concrete drying shrinkage, a drying factor that is 1/2 of the ultimate drying shrinkage is obtained from a time-dependent characteristic coefficient obtained by multiplying a factor that affects the drying shrinkage of concrete as a coefficient. A drying period calculation reference period that reaches the shrinkage rate is set, and an extrapolated primary complementary coefficient is obtained based on the drying period calculation reference period and one short-term drying period measurement data. An early estimation method of concrete drying shrinkage rate has been proposed, which is characterized by estimating the drying shrinkage rate of concrete when an arbitrary drying period has elapsed after the drying period calculation reference period from the first-order complementary coefficient.

However, these evaluation methods can give a very appropriate final drying shrinkage strain within a certain range of materials and blends, but they are not universal evaluation methods.
An example in which the application of the rapid evaluation method shown in the prior art is not necessarily appropriate is shown in FIG. 1 (comparative example).
Fig. 1 shows the dry shrinkage strain of concrete with the composition shown in Table 1 below, measured using ordinary Portland cement, according to JIS A 1129-2 Annex A. The value is estimated.
In addition, each material shown in Table 1 is the same as the material used by the 1st this invention mentioned later.

Specifically, FIG. 1 shows the above-mentioned Architectural Institute of Japan “Contraction Cracking Control Design and Construction Guidelines (Draft) of Reinforced Concrete Buildings” (Previous Rapid Evaluation Method 1)) and Imamoto ’s “Concrete Based on Short-Term Data”. This shows a case where the final value is estimated from the drying shrinkage strain data up to about 28 days using the “Research on Drying Shrinkage Strain Prediction” (Previous Rapid Evaluation Method 2)).
In addition, the prediction formula of the drying strain is predicted using the above formula (1) and the above formula (1) ′ (volume surface area ratio V / S = 22.2 mm).
From FIG. 1, it can be seen that when the period from the material age t ₀ day (drying start date) to the material age t day (hereinafter, the drying period) is short, the estimated value of the final value of the drying shrinkage strain obtained is increased. It is clear from FIG. 1 and is not a sufficient method as an early estimation method of concrete drying shrinkage.

JP 2008-8753 A

Rapid evaluation method of the Architectural Institute of Japan “Control Design for Shrinkage Cracks, Construction Guidelines (Draft), Commentary on Reinforced Concrete Buildings”, pp. 53-60, and the appendix pp. 186-190 Japan Society of Civil Engineers "Standard Specification for Concrete [Design]", pp. 45-46 Keiichi Imamoto, Toshie Ishii, Tetsushi Kaneda, Haruki Momose, Keisuke Fujimori: Research on prediction of drying shrinkage strain of concrete based on short-term data, Structural Architectural Proceedings No. 602, pp. 15-20, 2006.4

The object of the present invention is to solve the above-mentioned problems, and is an early evaluation method for concrete drying shrinkage strain. From an actual measurement value of concrete short-term age shrinkage strain, concrete drying shrinkage strain at an arbitrary long-term age Is to provide an early evaluation method of concrete drying shrinkage strain, which can be determined with high accuracy and early.
Specifically, the drying corresponding to the age of about 35 days when the ready mixed concrete to be used is determined and until the start of construction, that is, the compressive strength of the concrete tested in the laboratory is found to satisfy the nominal strength. In the period (drying period 28 days), a rapid evaluation method for accurately estimating the drying shrinkage strain of concrete at a long age, for example, 6 months of age is proposed.

The early evaluation method of drying shrinkage strain of concrete of the present invention (first invention)
(1) About concrete to be evaluated, a drying period of 28 days (age 35) under conditions of temperature 20 ± 2 ° C. and humidity 60 ± 5% from 7 days after the age (t ₀ = 7, starting date of drying) The drying shrinkage strain (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) is measured in any of a plurality of drying periods up to a day: t = 35)
Furthermore, with respect to the concrete to be evaluated, from 7 days after the age of the material (t ₀ = 7, starting date of drying material) to a drying period of 28 days (35 days of age: t = 35) under the condition of a temperature of 80 ± 3 ° C. Drying and drying shrinkage strain (ε _sh (t, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) (t ₀ = 7, t = 35) in the drying period 28 days (35 days of age: t = 35) Measure and
(2) Measured value (ε _sh (35, t ₀ ) of drying shrinkage strain in the drying period 28 days (material age 35 days: t = 35) measured under the condition of temperature 80 ± 3 ° C. in (1) above. ₈₀ ) (× 10 ⁻⁶ ) (t ₀ = 7), and the drying shrinkage strain value (ε _sh (35, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) on the 28th day of the drying period at a temperature of 80 ± 3 ° C. ) (T ₀ = 7) and the final dry shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5%. Calculate the final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5% of the target concrete,
(3) In the following formula (1), the final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at the temperature 20 ± 2 ° C. and the humidity 60 ± 5% obtained in the above (2) and the above ( A plurality of measured dry shrinkage strains (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) (t ₀ ) until the drying period of 28 days at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5% measured in 1) = ₂₀ ), α ₂₀ and β ₂₀ are calculated by the least square method,

(In the above formula, ε _sh (t, t ₀ ) is the drying shrinkage strain difference (× 10 ⁻⁶ ) from the drying start material age day (t ₀ : material age 7 days) to the material age t day, and ε _sh∞ is Final drying shrinkage strain value (× 10 ⁻⁶ ), α and β are coefficients indicating the degree of progress of drying)
(4) Final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at the temperature 20 ± 2 ° C. and the humidity 60 ± 5% obtained in the above (2), α obtained in the above (3) ₂₀ and β ₂₀ are applied to the above equation (1) to estimate a dry shrinkage strain value (ε _sh20 (t _L , t ₀ )) (× 10 ⁻⁶ ) of an arbitrary long-term age. This is an early evaluation method for drying shrinkage strain of concrete.

Preferably, in the method for early evaluation of the drying shrinkage strain of the concrete according to the present invention (the first invention), the drying shrinkage strain value (ε _sh (35, t ₀ )) at a temperature of 80 ± 3 ° C. on the 28th day of the drying period. ₈₀ ) (× 10 ⁻⁶ ) (t ₀ = 7) and final dry shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5%. The relational expression
(1) About a plurality of concretes, after 7 days of age (t ₀ = 7, drying start material age), the temperature is 20 ± 2 ° C. and the humidity is 60 ± 5%, and the drying period is 6 months. The drying shrinkage strain (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) (t ₀ = 7) in any of a plurality of drying periods up to 6 months is measured,
Further, the plurality of concretes are dried at a temperature of 80 ± 3 ° C. until a drying period of 28 days after a material age of 7 days (t ₀ = 7, drying start material age day). The shrinkage strain (ε _sh (35, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) (t ₀ = 7) was measured,
(2) Measured value (ε _sh (t, t ₀ ) ₂₀ ) (× 10) of drying shrinkage strains in a plurality of drying periods measured under the conditions of temperature 20 ± 2 ° C. and humidity 60 ± 5% in (1) above. ⁻⁶ ) (t ₀ = 7), the following formula (1):

(In the above formula, ε _sh (t, t ₀ ) is the drying shrinkage strain difference (× 10 ⁻⁶ ) from the drying start material age day (t ₀ : material age 7 days) to the dry material age t day, ε _sh∞ Is the final drying shrinkage strain value (× 10 ⁻⁶ ), and α and β are coefficients indicating the degree of drying)
To calculate the final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ), α ₂₀ and β ₂₀ at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5%,
(3) The final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5% and a drying period of 28 days at a temperature of 80 ° C. (t = 35) Approximating the relationship with the dry shrinkage strain value (ε _sh (t, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) (t ₀ = 7) by a linear expression to determine the relational expression .

The early evaluation method of the drying shrinkage strain of the concrete of the present invention (second invention)
(1) For concrete to be evaluated, from 7 days after the age of the material (t ₀ = 7, age of starting drying material), at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5%, and at a temperature of 80 ± 3 ° C. The drying shrinkage strains (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) and (ε _sh (t, t ₀ ) ₈₀ ) in any of a plurality of drying periods up to 28 days under the conditions of (× 10 ⁻⁶ ) was measured,
(2) Using measured values (ε _sh (t, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) of drying shrinkage strains in a plurality of drying periods measured under the condition of temperature 80 ± 3 ° C. in (1) above. Following formula (1):

(In the above formula, ε _sh (t, t ₀ ) is the drying shrinkage strain difference (× 10 ⁻⁶ ) from the drying start material age day (t ₀ : material age 7 days) to the material age t day, and ε _sh∞ is Final drying shrinkage strain value (× 10 ⁻⁶ ), α and β are coefficients indicating the degree of progress of drying)
To calculate the final drying shrinkage strain value (ε _sh∞80 ) (× 10 ⁻⁶ ) at a temperature of 80 ± 3 ° C.
(3) Using the final dry shrinkage strain value (ε _sh∞80 ) (× 10 ⁻⁶ ) at a temperature of 80 ± 3 ° C. calculated in (2) above, the final dry shrinkage strain value at a temperature of 80 ± 3 ° C. ( _ε sh∞80) (× ^{10 -6),} condition of 20 ± 2 ℃ of temperature and a final drying shrinkage strain values in humidity _{60 ± 5% (ε sh∞20)} (× 10 -6) separately predetermined relationship between The final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5% of the target concrete is calculated by the _equation ,
(4) In the above formula (1), the final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at the temperature 20 ± 2 ° C. and the humidity 60 ± 5% obtained in the above (3) and the above ( By applying a plurality of measured dry shrinkage strain values (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) measured in 1) until the drying period of 28 days, α ₂₀ and β ₂₀ are determined by the least square method. Calculate
(5) Final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at 20 ± 2 ° C. and 60 ± 5% humidity obtained in (3) above, α obtained in (4) above ₂₀ and β ₂₀ are applied to the above equation (1) to estimate a dry shrinkage strain value (ε _sh20 (t _L , t ₀ )) (× 10 ⁻⁶ ) of an arbitrary long-term age. This is an early evaluation method for drying shrinkage strain of concrete.

Preferably, in the method for early evaluation of the drying shrinkage strain of the concrete of the present invention (second invention), the final drying shrinkage strain value (ε _sh∞80 ) (× 10 ⁻⁶ ) at a temperature of 80 ± 3 ° C. and the temperature Separately determined relational expressions with final drying shrinkage strain values (ε _sh∞20 ) (× 10 ⁻⁶ ) at 20 ± 2 ° C. and humidity 60 ± 5% are:
(1) About a plurality of concretes, after 7 days of age (t ₀ = 7, drying start material age), the temperature is 20 ± 2 ° C. and the humidity is 60 ± 5%, and the drying period is 6 months. Measure the drying shrinkage strain (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) in any number of drying periods up to 6 months,
Further, the plurality of concretes are dried up to a drying period of 28 days under conditions of a temperature of 80 ± 3 ° C. from 7 days after the material age (t ₀ = 7, drying start material age day), and the drying period is up to 28 days. The drying shrinkage strain (ε _sh (t, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) in a plurality of drying periods was measured,
(2) Measured value (ε _sh (t, t ₀ ) ₂₀ ) (× 10) of drying shrinkage strains in a plurality of drying periods measured under the conditions of temperature 20 ± 2 ° C. and humidity 60 ± 5% in (1) above. ^-6 ) and measured value of drying shrinkage strain in a plurality of drying periods measured under the condition of temperature 80 ± 3 ° C. in the above (1) (ε _sh (t, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) Using the following formula (1):

(In the above formula, ε _sh (t, t ₀ ) is the drying shrinkage strain difference (× 10 ⁻⁶ ) from the drying start material age day (t ₀ : material age 7 days) to the dry material age t day, ε _sh∞ Is the final drying shrinkage strain value (× 10 ⁻⁶ ), and α and β are coefficients indicating the degree of drying)
, Final dry shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at temperature 20 ± 2 ° C. and humidity 60 ± 5%, α ₂₀ and β ₂₀ , and final dry shrinkage strain at temperature 80 ± 3 ° C. _{Calculate the} value (ε _sh∞80 ) (× 10 ⁻⁶ ), α ₈₀ and β ₈₀ ,
(3) Final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and humidity of 60 ± 5% and a final drying shrinkage strain value at a temperature of 80 ° C. (ε _{sh). ∞80} ) (× 10 ⁻⁶ ) is approximated by a linear expression to determine the relational expression.

  More preferably, in the early evaluation method for drying shrinkage strain of the concrete according to the first aspect of the invention and the second aspect of the invention, separately determined relational expressions are high-fluidity concrete, medium-fluidity concrete, It is different from the case of ordinary concrete.

  More preferably, in the early evaluation method of the drying shrinkage strain of the concrete of the first invention and the second invention and the early evaluation method of the drying shrinkage strain of the other concrete of the invention, an arbitrary long-term drying period is used. Has a drying period of 6 months.

  More preferably, in the method for early evaluation of the drying shrinkage strain of the concrete according to the first aspect of the invention and the second aspect of the invention, the relational expression is obtained when the concrete is high-fluidity concrete or medium-fluidity concrete; It is constructed separately from other ordinary concrete.

  The early evaluation method of concrete dry shrinkage strain according to the present invention measures an actual measurement value of dry shrinkage strain of concrete in a short-term age, and thereby determines the dry shrinkage strain of concrete in an arbitrary long-term age, for example, a drying period of 6 months. It becomes possible to determine with high accuracy and early.

It is a correlation figure of an example which shows the correlation with the estimated value of the drying shrinkage distortion by the early evaluation (comparative example) of the conventional drying shrinkage distortion, and a drying period. Correlation between drying period and measured value of drying shrinkage strain when various concrete specimens were dried from 7 days old (drying age 0 days) under the conditions of temperature 20 ± 2 ℃ and humidity 60 ± 5% FIG. The measured values of drying period and drying shrinkage strain when various other concrete specimens were dried under the conditions of a temperature of 20 ± 2 ° C. and humidity of 60 ± 5% ° C. from 7 days of age (0 days of dry material) It is an example of a correlation diagram which shows correlation of these. Correlation diagram of an example showing the correlation between the drying period and the measured value of drying shrinkage strain when various concrete specimens are dried at a temperature of 80 ± 3 ° C from 7 days of age (0 days of dry material) It is. An example showing the correlation between the drying period and the measured value of drying shrinkage strain when various other concrete specimens were dried at a temperature of 80 ± 3 ° C. from 7 days of age (0 days of dry material) It is a correlation diagram. Various concrete specimens were dried for 28 days under the condition of a temperature of 80 ± 3 ° C. from 7 days of age (dry material age of 0 days), and the drying shrinkage strain value (ε _sh (35, t ₀ ) on the 28th day of the drying period. ₈₀ ) (× 10 ⁻⁶ ) (t ₀ = 7) and various concrete specimens from 7 days of age (0 days of dry material) to a temperature of 20 ± 2 ° C. and humidity of 60 ± 5%. It is a figure which shows the relational expression of a correlation with the last dry shrinkage strain value estimated from each dry shrinkage strain value at the time of carrying out the moon drying. The actual measurement value of the drying shrinkage strain when the concrete specimen was dried for 6 months under the conditions of a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5% from a material age of 7 days (dry material age of 0 days) It is a figure of an example which shows the relationship with the estimated value of the drying shrinkage distortion of the drying period of 6 months estimated by the evaluation method of this invention. FIG. 4 is a correlation diagram of an example showing a correlation between measured values and estimated values by the evaluation method of the first aspect of the drying period and drying shrinkage strain of various concrete specimens at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5%. is there. Another example showing the correlation between measured values and estimated values by the evaluation method of the first aspect of the drying period and drying shrinkage strain of other various concrete specimens at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5%. It is a correlation diagram. It is a flowchart of an example which shows roughly the procedure of the database relational expression construction for the early evaluation method of the drying shrinkage strain of the 1st present invention. It is a flowchart of an example which shows roughly the procedure of the early evaluation method of the drying shrinkage | contraction strain of 1st this invention. Final dry shrinkage strain values estimated from dry shrinkage strain values when various concrete specimens were dried for 28 days under the condition of a temperature of 80 ± 3 ° C. from 7 days old (dry age 0 days) Correlation between the final dry shrinkage strain value estimated from each dry shrinkage strain value when concrete specimens were dried for 28 days at a temperature of 20 ± 2 ° C and humidity of 60 ± 5% from 7 days of age. FIG. Estimated by the measured value of drying shrinkage strain when a concrete specimen is dried for 6 months from the age of 7 days under the conditions of temperature 20 ± 2 ° C. and humidity 60 ± 5% and the evaluation method of the second aspect of the present invention. It is a figure of an example which shows the relationship with the estimated value of the drying shrinkage | contraction distortion | strain of 6 months of drying. Correlation diagram of an example showing the correlation between measured values and estimated values by the evaluation method of the second aspect of the present invention with respect to the drying period and drying shrinkage strain of various concrete specimens at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5% ° C. It is. Another example showing the correlation between the actual measurement value and the estimated value by the evaluation method of the second aspect of the drying period and drying shrinkage strain of other various concrete specimens at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5% FIG. It is a flowchart of an example which shows roughly the procedure of the database relational expression construction for the early evaluation method of the drying shrinkage strain of the 2nd present invention. It is a flowchart of an example which shows roughly the procedure of the early evaluation method of the drying shrinkage | contraction strain of 2nd this invention.

The early evaluation method of concrete drying shrinkage strain of the present invention will be described in detail by the following preferred examples, but is not limited thereto.
[A. First Invention]
The concrete evaluation method (first present invention) of the concrete drying shrinkage strain of the present invention will be described in detail with reference to the flowcharts of FIGS.
FIG. 10 shows the dry shrinkage strain (ε _sh (t _L , t ₀ ) (× 10) at the long-term age t _L (day) of the concrete to be measured in the early evaluation method of the concrete dry shrinkage strain of the first invention. It is a flowchart which shows roughly construction of the relational expression of the database determined beforehand for calculating ^-6 )). The drying starts ages _{(t 0)} is according to JIS A 1129-2 Annex A, the 7 days.
FIG. 11 shows the drying shrinkage at the long-term age t _L (day) of the concrete to be evaluated by using the relational expression of the database previously constructed by the method for early evaluation of the concrete drying shrinkage strain of the first present invention. The flowchart for calculating the strain (ε _sh (t _L , t ₀ ) (× 10 ⁻⁶ )) is shown.

(A-1. Measured value (ε _sh (35, t ₀ ) ₈₀ ) (× 10) of the drying shrinkage strain at the drying period of 28 days at a temperature of 80 ± 3 ° C. used in the evaluation method of the present invention (first invention). ⁻⁶ ) (t ₀ = 7) and the final dry shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5%)
In order to eliminate as much as possible the estimation error of the excessive final drying shrinkage strain value that can occur when the existing rapid evaluation method is used, a plurality of concrete specimens are produced from the same concrete.
As a suitable example, a total of 12 types of concretes having different materials and their blending amounts were prepared.
The following materials were used for concrete.
・ Cement: Ordinary Portland cement (manufactured by Sumitomo Osaka Cement Co., Ltd.)
Fine aggregate: river sand or mountain sand. Table 2 shows the density and water absorption rate.
Coarse aggregate: river gravel, limestone, hard sandstone, tuff or sandstone. Table 2 shows the density and water absorption rate.
Admixture: Limestone fine powder (Blaine specific surface area 4580 cm ² / g, density 2.71 g / cm ³ )
・ High performance water reducing agent: Leo Build 8000S (manufactured by BASF Japan Ltd.)
-High performance water reducing agent: Tupole NV-G5 (manufactured by Takemoto Yushi Co., Ltd.)
AE water reducing agent: Pozzolith No. 70 (manufactured by BASF Japan)
・ Water: Tap water

Table 3 shows the concrete mix.
In Table 3, the slump is a value measured according to JIS A 1101, the slump flow is measured according to JIS A 1150, and the air amount is a value measured according to JIS A 1128.

  According to the JIS standard (JIS A 1129-2 Annex A) using each of the concrete Nos. 2 to 13 of Table 3 prepared above, a plurality of test specimens, for example, six concrete prism test specimens (100 × 100 × 400 mm prismatic specimen). Specifically, a concrete prismatic specimen was prepared in a constant temperature and humidity chamber with a room temperature of 20 ± 2 ° C and a humidity of 80% or more. Underwater curing was performed at 20 ± 2 ° C. for the 6 days until.

Next, (1) a plurality of test specimens of the concrete prismatic test specimens of Nos. 2 to 13, for example, three test specimens out of six specimens were used after 7 days of age (after the underwater curing: t ₀ = 7, Dry for 6 months under the conditions of temperature 20 ± 2 ° C., humidity 60 ± 5% (JIS A 1129-2 Annex A) (abbreviated as “temperature 20 ° C.”) A plurality of any age days, for example, a drying period of 1 day (age 8 days: t = 8), 3 days (age 10 days: t = 10), 7 days (age 14 days: t = 14), 14 points (material age 21 days: t = 21), 28 days (material age 35 days: t = 35), 6 points (t−t ₀ ) essential for actual measurement, and any arbitrary one shown in FIGS. 2 and 3 co analogously the drying shrinkage strain in a plurality of drying period _{(t-t 0)} to _{(ε sh (t, t 0} ) 20) to JIS a 1129-2 Annex a It was measured for each cleat specimen. The measurement of the drying shrinkage strain up to the drying period of 6 months may be more than the above.
The results are shown in FIG. 2 and FIG. However, the actual measurement value of the drying shrinkage strain in each drying period was the average value of the above three specimens of each concrete specimen in the drying period.

Further, among the concrete specimens Nos. 2 to 13 in Table 3 prepared above, the remaining plurality of specimens, for example, three concrete prismatic specimens (100 × 100 × 400 mm) were used (age) 6 days up to 7 days under water curing at 20 ± 2 ° C), after 7 days of age (after underwater curing: t ₀ = 7, age of drying start material age) temperature 80 ± 3 ° C (humidity is not particularly adjusted) The drying shrinkage strain (ε _sh (35) in the drying period 28 days (35 days (t)) was dried under the condition of approximately 0%) (abbreviated as “temperature 80 ° C.”). 7) ₈₀ ) was measured for each concrete specimen in accordance with JIS A 1129-2 Annex A.

The drying period at a temperature of 80 ± 3 ° C. includes a final drying shrinkage strain value (ε _sh∞20 ) at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5% and a drying period (t−t ₀ ) at a temperature of 80 ± 3 ° C. ) If the relationship with the strain (ε _sh (t, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) of the day can be approximated by a linear expression, the drying period (t−t ₀ ) should be set to an arbitrary period. There is no particular limitation on the 28th.

  The drying shrinkage strain is obtained by using a contact gauge or the like by attaching a gauge plug using a highly heat-resistant room temperature curing type two-component epoxy resin adhesive that exhibits a glass transition temperature of 102 ° C. by the TMA method after curing. It can be measured. This room temperature curing type two-component epoxy resin adhesive is a liquid epoxy resin at room temperature containing bisphenol A type epoxy resin, reactive diluents such as diepoxy as additives, and other additives for improving adhesion performance. The main agent and the curing agent component are preferably composed of aliphatic polyamines such as meta-xylene diamine, alicyclic polyamines such as isophorone diamine, etc., which use polyamines that are liquid at room temperature as curing agent components. It is.

Table 4 shows the results of the drying shrinkage strain values measured at the temperature of 80 ° C. for the drying period of 28 days (material age 35 days). However, the actual measurement values in Table 4 are the average values of a plurality of test specimens of each concrete specimen during the drying period (28 days), for example, the above three specimens. In FIG. 4 and FIG. A plurality of dry shrinkage measured values measured at 0 ° C. up to a drying period of 28 days are shown. The strain value is an average value of a plurality of test specimens of each concrete specimen, for example, the above three specimens in each drying period.

(2) Measured value (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻ of dry shrinkage strain at any age t at the temperature 20 ° C. shown in FIG. 2 and FIG. ⁶ ), the final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) and α ₂₀ , β ₂₀ at a temperature of 20 ° C. were determined by the following method (1) by the method of least squares. Table 5 below shows the final dry shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) obtained for each concrete specimen at a temperature of 20 ° C.

However, in the above formula (1), ε _sh (t, t ₀ ) is the drying shrinkage strain difference (× 10 ⁻⁶ ) from the drying start material age day (t ₀ : material age 7 days) to the material age t days, ε _sh∞ is a final drying shrinkage strain value (× 10 ⁻⁶ ), and α and β are coefficients _{indicating the} degree of drying progress.

(3) Next, the plurality of, for example, the final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ° C. in Table 5 is used as the Y axis at the temperature of 80 ° C. in Table 4 above. Drying shrinkage strain (ε _sh (35,7) ₈₀ ) (× 10 ⁻⁶ ) value on the 28th day of drying period is X axis and high fluidity concrete, medium fluidity concrete (compound No. 2-7) and other ordinary concrete (Formulation Nos. 8 to 13), the correlation is shown in FIG. 6, and a correlation equation (primary equation) between X and Y is derived by the least square method.
The obtained correlation equation is expressed in terms of the drying shrinkage strain value (ε _sh (35, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) (t ₀ = 7) at the temperature 80 ± 3 ° C. and the temperature. A predetermined relational expression with a final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at 20 ± 2 ° C. and a humidity of 60 ± 5% is used.
However, the above relational expression is constructed by dividing the concrete into high fluid concrete and medium fluid concrete and normal concrete.

[A-2. Evaluation of drying shrinkage strain of concrete of the present invention (first invention)]
Next, a method for estimating and evaluating the dry shrinkage strain value of an arbitrary long-term age of the concrete to be evaluated, for example, the dry shrinkage strain value of concrete having a drying period of 6 months, will be described using the above relational expression.
(1) Concrete of interest, the in the same manner as "build relationship used in the evaluation method of A-1. The present invention," (1), the age 7 days after the cured in water (t 0 _{= 7,} The material is dried under the conditions of temperature 20 ± 2 ° C. and humidity 60 ± 5% (JIS A 1129-3 Annex A) (abbreviated as “20 ° C.”), and then the drying period is 28 days. The drying shrinkage strain (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) in a plurality of arbitrary drying periods was measured for each concrete specimen in accordance with JIS A 1129-2 Annex A.
Further, in the same manner as in “A-1. Construction of relational expressions used in the evaluation method of the present invention” (1), the temperature is 80 ± 3 ° C. (humidity is not particularly adjusted but is almost 0%) (“80 ° C.” The measured value (ε _sh (35,7) ₈₀ ) (× 10 ⁻⁶ ) of the drying shrinkage strain at the drying period 28 days (t = 35) is obtained.

(2) Using the drying shrinkage strain value (ε _sh (28, t ₀ ) ₈₀ ) (10 × ⁻⁶ ) on the 28th day of the drying period measured under the condition of the temperature of 80 ° C. in the above (1), A-1. Construction of relational expression used in evaluation method of the present invention "(3), applying the correlation expression (Fig. 6) determined in advance, final drying shrinkage strain at 20 ° C of the concrete to be evaluated The value (ε _sh∞20 ) (× 10 ⁻⁶ ) is calculated.
However, when the target concrete is high-fluidity concrete and medium-fluidity concrete, the relations constructed for these high-fluidity and medium-fluidity concretes are used. Use the formula.

(3) Next, in the following formula (1), the final dry shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at 20 ° C. obtained in the above (2) and the temperature measured in the above (1) Applying a plurality of dry shrinkage strain measurements (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) up to a drying period of 28 days at 20 ° C., α ₂₀ and β ₂₀ are determined by the least square method.

However, in the above formula (1), ε _sh (t, t ₀ ) is the drying shrinkage strain difference (× 10 ⁻⁶ ) from the drying start material age day (t ₀ : material age 7 days) to the material age t days, ε _sh∞ is a final drying shrinkage strain value (× 10 ⁻⁶ ), and α and β are coefficients _{indicating the} degree of drying progress.

(4) Next, the final dry shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at 20 ° C. obtained in (2) above, and α ₂₀ and β ₂₀ obtained in (3) above are Applying to the equation (1), a drying shrinkage strain value in an arbitrary drying period, for example, a drying period of 6 months, is estimated and evaluated for the concrete specimen to be evaluated (FIGS. 7, 8, and 9).

(5) Even if the type of concrete contained in the concrete test specimen is different from the above-mentioned example of the present application, it is basically the same as the above-mentioned procedures (1) to (4), and the drying period at 80 ° C. is 28 days. Obtain the measured value (ε _sh (35,7) ₈₀ ) (× 10 ⁻⁶ ) of the drying shrinkage strain, depending on whether the concrete type is high fluid concrete, medium fluid concrete, or other ordinary concrete A final drying shrinkage strain value at a temperature of 20 ° C. is obtained from the approximate expression of FIG.
Next, using a plurality of measured dry shrinkage strain values up to the drying period of 28 days, the final dry shrinkage strain value A at a temperature of 20 ° C. is substituted into the equation (1), and α ₂₀ and β ₂₀ are calculated by the least square method. Ask.
Obtaining the values of α ₂₀ and β ₂₀ and the final drying shrinkage strain value A obtained in the formula (1) to obtain the drying shrinkage strain value of the concrete specimen of any blending example in any long-term drying period. it can.

[B. Second Invention]
The method for early evaluation of concrete drying shrinkage strain (second invention) of the present invention will be described in detail with reference to the flowcharts of FIGS.
FIG. 16 shows the dry shrinkage strain (ε _sh (t _L ) at the long-term age t _L (day) of the concrete to be measured in the method for early evaluation of the concrete dry shrinkage strain of the second invention (second invention). , T ₀ ) (× 10 ⁻⁶ )) is a flowchart schematically showing the construction of a relational expression of a predetermined database. The drying starts ages _{(t 0)} is according to JIS A 1129-2 Annex A, the 7 days.
FIG. 17 shows the drying shrinkage at the long-term age t _L (day) of the concrete to be evaluated by using the relational expression of the database previously constructed by the method for early evaluation of the concrete drying shrinkage strain of the second invention. The flowchart for calculating the strain (ε _sh (t _L , t ₀ ) (× 10 ⁻⁶ )) is shown.

(B-1. Final drying shrinkage strain value (ε _sh∞80 ) (× 10 ⁻⁶ ) at a temperature of 80 ± 3 ° C., temperature of 20 ± 2 ° C. and humidity used in the evaluation method of the present invention (second invention) Construction of a predetermined relational expression with the final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at 60 ± 5%)
In the same manner as in “A-1. Construction of relational expressions used in the evaluation method of the present invention (first invention)”, concrete prism test specimens were prepared using each of Nos. 2 to 13 and until the age of 7 days was reached. For 6 days, water curing was performed at 20 ± 2 ° C.

(1) Next, a plurality of test specimens of each of the concrete prisms No. 2 to No. 13 described above, for example, 3 specimens out of 6 specimens were used after 7 days of age (after the underwater curing: t ₀ = 7, Dry for 6 months under the conditions of temperature 20 ± 2 ° C., humidity 60 ± 5% (JIS A 1129-2 Annex A) (abbreviated as “temperature 20 ° C.”) A plurality of any age days, for example, a drying period of 1 day (age 8 days: t = 8), 3 days (age 10 days: t = 10), 7 days (age 14 days: t = 14), 14 points (material age 21 days: t = 21), 28 days (material age 35 days: t = 35), 6 points (t−t ₀ ) essential for actual measurement, and any arbitrary one shown in FIGS. 2 and 3 co analogously the drying shrinkage strain in a plurality of drying period _{(t-t 0)} to _{(ε sh (t, t 0} ) 20) to JIS a 1129-2 Annex a It was measured for each cleat specimen. The measurement of the drying shrinkage strain up to the drying period of 6 months may be more than the above.
The results are shown in FIG. 2 and FIG. However, the actual measurement value of the drying shrinkage strain in each drying period was the average value of the above three specimens of each concrete specimen in the drying period.

Further, among the concrete specimens Nos. 2 to 13 in Table 3 prepared above, the remaining plurality of specimens, for example, three concrete prismatic specimens (100 × 100 × 400 mm) were used (age) 6 days up to 7 days under water curing at 20 ± 2 ° C), after 7 days of age (after underwater curing: t ₀ = 7, age of drying start material age) temperature 80 ± 3 ° C (humidity is not particularly adjusted) The drying shrinkage value (ε _sh (t, 7) ₈₀ ) (× 10 ⁻⁶ ) for any of a plurality of drying periods up to the drying period of 28 days under the condition of approximately 0%) Was measured for each concrete specimen in accordance with JIS A 1129-2 Annex A.

The drying period at a temperature of 80 ± 3 ° C. includes a final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5%, and drying at a temperature of 80 ± 3 ° C. If the relationship with the final drying shrinkage strain value (ε _sh∞80 ) (× 10 ⁻⁶ ) calculated from the period (t−t ₀ ) day can be approximated by a linear expression, the drying period (t−t ₀ ) day Can be set to an arbitrary period, and is not particularly limited to 28 days.

  The drying shrinkage strain is obtained by using a contact gauge or the like by attaching a gauge plug using a highly heat-resistant room temperature curing type two-component epoxy resin adhesive that exhibits a glass transition temperature of 102 ° C. by the TMA method after curing. It can be measured. This room temperature curing type two-component epoxy resin adhesive is a liquid epoxy resin at room temperature containing bisphenol A type epoxy resin, reactive diluents such as diepoxy as additives, and other additives for improving adhesion performance. The main agent and the curing agent component are preferably composed of aliphatic polyamines such as meta-xylene diamine, alicyclic polyamines such as isophorone diamine, etc., which use polyamines that are liquid at room temperature as curing agent components. It is.

  4 and 5 show the results of a plurality of drying shrinkage strain values up to 28 days (35 days of age) at a measured temperature of 80 ° C. (Note that Table 4 shows the drying shrinkage on the 28th day of the drying period) Indicates strain value). However, the actual measurement value of the drying shrinkage strain in each drying period was an average value of a plurality of test specimens of each concrete specimen in the drying period, for example, the above three specimens.

(2) Measured values (ε _sh (t, t ₀ ) ₂₀ ) (×) of a plurality of drying shrinkage strains at each arbitrary age t at a temperature of 20 ° C. shown in FIG. 2 and FIG. 10 ⁻⁶ ) and the actually measured values of a plurality of drying shrinkage strains at any age t at the temperature of 80 ° C. shown in FIG. 4 and FIG. 5 measured in the above (1) (ε _sh (t, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) and the following equation (1), the final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at ₂₀ ° C. and α ₂₀ , β ₂₀ and the final at 80 ° C. The drying shrinkage strain value (ε _sh∞80 ) (× 10 ⁻⁶ ) and α ₈₀ and β ₈₀ were determined.
The final dry shrinkage strain value (ε _sh∞20 ) obtained for each concrete specimen at a temperature of 20 ° C. is shown in Table 5 above, and the final dry shrinkage strain value obtained for each concrete specimen at a temperature of 80 ° C. Table 6 shows (ε _sh∞80 ) (× 10 ⁻⁶ ).

However, in the above formula (1), ε _sh (t, t ₀ ) is the drying shrinkage strain difference (× 10 ⁻⁶ ) from the drying start material age day (t ₀ : material age 7 days) to the material age t days, ε _sh∞ is a final drying shrinkage strain value (× 10 ⁻⁶ ), and α and β are coefficients _{indicating the} degree of drying progress.

(3) Then, the final drying shrinkage strain values of the plurality of temperature 20 ° C. The ^{_{(ε sh∞20) (× 10 -6}} ) in the Y-axis, the final drying shrinkage strain values at the plurality of temperature ₈₀ ℃ (ε sh∞ ₈₀ ) (× 10 ⁻⁶ ) as the X axis, it is divided into high-fluidity concrete and medium-fluidity concrete (mixing No. 2-7) and other ordinary concrete (mixing No. 8-13), and the correlation is shown in FIG. The correlation equation (linear equation) between X and Y is derived by the least square method.
The obtained correlation open form is _{divided into a} final dry shrinkage strain value (ε _sh∞80 ) (× 10 ⁻⁶ ) at a temperature of 80 ± 3 ° C., and a final dry shrinkage strain value at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5%. The relational expression is determined in advance as (ε _sh∞20 ) (× 10 ⁻⁶ ).
However, the above relational expression is constructed by dividing the concrete into high fluid concrete and medium fluid concrete and normal concrete.

[B-2. Evaluation of drying shrinkage strain of concrete of the present invention (second invention)]
Next, a method for estimating and evaluating the dry shrinkage strain value of an arbitrary long-term age of the concrete to be evaluated, for example, the dry shrinkage strain value of concrete having a drying period of 6 months, will be described using the above relational expression.
(1) About concrete used as object, it is the same as said "B-1. Construction of the relational expression used for the evaluation method of this invention (2nd invention)" (1). t ₀ = 7, drying start material age day) under conditions of temperature 20 ± 2 ° C., humidity 60 ± 5% (JIS A 1129-3 Annex A) (abbreviated as “20 ° C.”), and then The drying shrinkage strain (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) in a plurality of arbitrary drying periods up to a drying period of 28 days is determined for each concrete specimen in accordance with JIS A 1129-2 Annex A. Measured.
Similarly, the drying shrinkage strain (ε _sh (t, t ₀ ) ₈₀ ) in a plurality of arbitrary drying periods up to a drying period of 28 days under the condition of a temperature of 80 ± 3 ° C. (abbreviated as “80 ° C.”) ( × 10 ⁻⁶ ) was measured for each concrete specimen in accordance with JIS A 1129-2 Annex A.

(2) Using the drying shrinkage strain values (ε _sh (28, t ₀ ) ₈₀ ) (10 × ⁻⁶ ) of a plurality of drying periods measured under the condition of the temperature of 80 ° C. in the above (1), the following formula ( Applying to 1), the final drying shrinkage strain value (ε _sh (t, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) at a temperature of 80 ° C. is calculated.

However, in the above formula (1), ε _sh (t, t ₀ ) is the drying shrinkage strain difference (× 10 ⁻⁶ ) from the drying start material age day (t ₀ : material age 7 days) to the material age t days, ε _sh∞ is a final drying shrinkage strain value (× 10 ⁻⁶ ), and α and β are coefficients _{indicating the} degree of drying progress.

(3) Using the final drying shrinkage strain value (ε _sh∞80 ) (10 × ⁻⁶ ) at a temperature of 80 ° C. calculated in (2) above, the above-mentioned “B. Evaluation method of the present invention (second invention)” By applying the correlation equation (Fig. 12) determined in advance in "3. Construction of relational expression used in (3)", the final drying shrinkage strain value (ε _sh∞20 ) at a temperature of 20 ° C of the concrete to be evaluated (× ^10-6 ) is calculated.
However, when the target concrete is high-fluidity concrete and medium-fluidity concrete, the relations constructed for these high-fluidity and medium-fluidity concretes are used. Use the formula.

(4) Next, in the following formula (1), the final dry shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at 20 ° C. obtained in the above (3) and the temperature measured in the above (1) Applying a plurality of dry shrinkage strain measurements (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) up to a drying period of 28 days at 20 ° C., α ₂₀ and β ₂₀ are determined by the least square method.

However, in the above formula (1), ε _sh (t, t ₀ ) is the drying shrinkage strain difference (× 10 ⁻⁶ ) from the drying start material age day (t ₀ : material age 7 days) to the material age t days, ε _sh∞ is a final drying shrinkage strain value (× 10 ⁻⁶ ), and α and β are coefficients _{indicating the} degree of drying progress.

(5) Next, the final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at 20 ° C. obtained in (3) above, and α ₂₀ and β ₂₀ obtained in (4) above are Applying to the formula (1), the drying shrinkage strain value in an arbitrary drying period, for example, a drying period of 6 months, is estimated and evaluated for the concrete specimen to be evaluated (FIGS. 13, 14, and 15).

(6) Even if the type of concrete contained in the concrete test specimen is different from the examples of the present application, the procedure is basically the same as the above (1) to (5), and the final dry strain value at 80 ° C. (ε _sh∞80 ) (× 10 ⁻⁶ ), and depending on whether the type of concrete is high-fluidity concrete, medium-fluidity concrete, or other ordinary concrete, the final formula at a temperature of 20 ° C. The drying shrinkage strain value A is determined.
Next, using a plurality of measured dry shrinkage strain values up to the drying period of 28 days, the final dry shrinkage strain value A at a temperature of 20 ° C. is substituted into the equation (1), and α ₂₀ and β ₂₀ are calculated by the least square method. Ask.
Obtaining the values of α ₂₀ and β ₂₀ and the final drying shrinkage strain value A obtained in the formula (1) to obtain the drying shrinkage strain value of the concrete specimen of any blending example in any long-term drying period. it can.

  The present invention can be applied to estimate drying shrinkage strain related to concrete cracks early and accurately depending on the type of concrete (high fluid concrete, medium fluid concrete, and other ordinary concrete). it can.

Claims (7)

(1) About concrete to be evaluated, a drying period of 28 days (age 35) under conditions of temperature 20 ± 2 ° C. and humidity 60 ± 5% from 7 days after the age (t ₀ = 7, starting date of drying) The shrinkage strain (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) in any of a plurality of drying periods up to t = 35) was measured, and the concrete age of the concrete to be evaluated After 7 days (t ₀ = 7, drying start material age day), drying was performed at a temperature of 80 ± 3 ° C. until a drying period of 28 days (material age 35 days: t = 35). Age 35 days: t = 35), the dry shrinkage strain (ε _sh (t, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) (t ₀ = 7, t = 35) was measured,
(2) Measured value (ε _sh (35, t ₀ ) of drying shrinkage strain in the drying period 28 days (material age 35 days: t = 35) measured under the condition of temperature 80 ± 3 ° C. in (1) above. ₈₀ ) (× 10 ⁻⁶ ) (t ₀ = 7), and the measured value (ε _sh (35, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) (t ₀ = 7) and a final dry shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5% The final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5% of the concrete to be evaluated is calculated,
(3) In the following formula (1), the final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at the temperature 20 ± 2 ° C. and the humidity 60 ± 5% obtained in the above (2) and the above ( A plurality of measured dry shrinkage strains (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) (t ₀ ) until the drying period of 28 days at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5% measured in 1) = ₂₀ ), α ₂₀ and β ₂₀ are calculated by the least square method,

(In the above formula, ε _sh (t, t ₀ ) is the drying shrinkage strain difference (× 10 ⁻⁶ ) from the drying start material age day (t ₀ : material age 7 days) to the material age t day, and ε _sh∞ is Final drying shrinkage strain value (× 10 ⁻⁶ ), α and β are coefficients indicating the degree of progress of drying)
(4) Final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at the temperature 20 ± 2 ° C. and the humidity 60 ± 5% obtained in the above (2), α obtained in the above (3) ₂₀ and β ₂₀ are applied to the above equation (1) to estimate a dry shrinkage strain value (ε _sh20 (t _L , t ₀ )) (× 10 ⁻⁶ ) of an arbitrary long-term age. An early evaluation method for drying shrinkage strain of concrete. In the early evaluation method of claim 1 of the concrete according drying shrinkage strain, drying period 28 days drying shrinkage strain measured value of the temperature _{80 ± 3 ℃ (ε sh (} 35, t 0) 80) (× 10 -6 ) (T ₀ = 7) and a final dry shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5%,
(1) About a plurality of concretes, after 7 days of age (t ₀ = 7, drying start material age), the temperature is 20 ± 2 ° C. and the humidity is 60 ± 5%, and the drying period is 6 months. The drying shrinkage strain (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) (t ₀ = 7) in any of a plurality of drying periods up to 6 months is measured,
Further, the plurality of concretes are dried at a temperature of 80 ± 3 ° C. until a drying period of 28 days after a material age of 7 days (t ₀ = 7, drying start material age day). The shrinkage strain (ε _sh (35, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) (t ₀ = 7) was measured,
(2) Measured value (ε _sh (t, t ₀ ) ₂₀ ) (× 10) of drying shrinkage strains in a plurality of drying periods measured under the conditions of temperature 20 ± 2 ° C. and humidity 60 ± 5% in (1) above. ⁻⁶ ) (t ₀ = 7), the following formula (1)

(In the above formula, ε _sh (t, t ₀ ) is the drying shrinkage strain difference (× 10 ⁻⁶ ) from the drying start material age day (t ₀ : material age 7 days) to the dry material age t day, ε _sh∞ Is the final drying shrinkage strain value (× 10 ⁻⁶ ), and α and β are coefficients indicating the degree of drying)
To calculate the final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ), α ₂₀ and β ₂₀ at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5%,
(3) The final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5% and a drying period of 28 days at a temperature of 80 ° C. (t = 35) is approximated by a linear expression to determine a relational expression with a drying shrinkage strain (ε _sh (t, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) (t ₀ = 7), An early evaluation method for drying shrinkage strain of concrete. (1) For concrete to be evaluated, from 7 days after the age of the material (t ₀ = 7, age of starting drying material), at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5%, and at a temperature of 80 ± 3 ° C. The drying shrinkage strains (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) and (ε _sh (t, t ₀ ) ₈₀ ) in any of a plurality of drying periods up to 28 days under the conditions of (× 10 ⁻⁶ ) was measured,
(2) Using measured values (ε _sh (t, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) of drying shrinkage strains in a plurality of drying periods measured under the condition of temperature 80 ± 3 ° C. in (1) above. The following formula (1):

(In the above formula, ε _sh (t, t ₀ ) is the drying shrinkage strain difference (× 10 ⁻⁶ ) from the drying start material age day (t ₀ : material age 7 days) to the material age t day, and ε _sh∞ is Final drying shrinkage strain value (× 10 ⁻⁶ ), α and β are coefficients indicating the degree of progress of drying)
To calculate the final drying shrinkage strain value (ε _sh∞80 ) (× 10 ⁻⁶ ) at a temperature of 80 ± 3 ° C.
(3) Using the final dry shrinkage strain value (ε _sh∞80 ) (× 10 ⁻⁶ ) at a temperature of 80 ± 3 ° C. calculated in (2) above, the final dry shrinkage strain value at a temperature of 80 ± 3 ° C. ( _ε sh∞80) (× ^{10 -6),} condition of 20 ± 2 ℃ of temperature and a final drying shrinkage strain values in humidity _{60 ± 5% (ε sh∞20)} (× 10 -6) separately predetermined relationship between The final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and a humidity of 60 ± 5% of the target concrete is calculated by the _equation ,
(4) In the above formula (1), the final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at the temperature 20 ± 2 ° C. and the humidity 60 ± 5% obtained in the above (3) and the above ( By applying a plurality of measured dry shrinkage strain values (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) measured in 1) until the drying period of 28 days, α ₂₀ and β ₂₀ are determined by the least square method. Calculate
(5) Final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at 20 ± 2 ° C. and 60 ± 5% humidity obtained in (3) above, α obtained in (4) above ₂₀ and β ₂₀ are applied to the above equation (1) to estimate a dry shrinkage strain value (ε _sh20 (t _L , t ₀ )) (× 10 ⁻⁶ ) of an arbitrary long-term age. An early evaluation method for drying shrinkage strain of concrete. In the early evaluation method of the drying shrinkage strain of concrete according to claim 1, the final dry shrinkage strain value (ε _sh∞80 ) (× 10 ^-6 ) at a temperature of 80 ± 3 ° C, a temperature of 20 ± 2 ° C and a humidity of 60 A separate predetermined relational expression with the final dry shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at ± 5% is
(1) About a plurality of concretes, after 7 days of age (t ₀ = 7, drying start material age), the temperature is 20 ± 2 ° C. and the humidity is 60 ± 5%, and the drying period is 6 months. The drying shrinkage strain value (ε _sh (t, t ₀ ) ₂₀ ) (× 10 ⁻⁶ ) in an arbitrary plurality of drying periods up to 6 months is measured,
Further, the plurality of concretes are dried up to a drying period of 28 days under conditions of a temperature of 80 ± 3 ° C. from 7 days after the material age (t ₀ = 7, drying start material age day), and the drying period is up to 28 days. The drying shrinkage strain (ε _sh (t, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) in a plurality of drying periods was measured,
(2) Measured value (ε _sh (t, t ₀ ) ₂₀ ) (× 10) of drying shrinkage strains in a plurality of drying periods measured under the conditions of temperature 20 ± 2 ° C. and humidity 60 ± 5% in (1) above. ^-6 ) and measured value of drying shrinkage strain in a plurality of drying periods measured under the condition of temperature 80 ± 3 ° C. in the above (1) (ε _sh (t, t ₀ ) ₈₀ ) (× 10 ⁻⁶ ) Using the following formula (1)

(In the above formula, ε _sh (t, t ₀ ) is the drying shrinkage strain difference (× 10 ⁻⁶ ) from the drying start material age day (t ₀ : material age 7 days) to the dry material age t day, ε _sh∞ Is the final drying shrinkage strain value (× 10 ⁻⁶ ), and α and β are coefficients indicating the degree of drying)
, Final dry shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at temperature 20 ± 2 ° C. and humidity 60 ± 5%, α ₂₀ and β ₂₀ , and final dry shrinkage strain at temperature 80 ± 3 ° C. _{Calculate the} value (ε _sh∞80 ) (× 10 ⁻⁶ ), α ₈₀ and β ₈₀ ,
(3) Final drying shrinkage strain value (ε _sh∞20 ) (× 10 ⁻⁶ ) at a temperature of 20 ± 2 ° C. and humidity of 60 ± 5% and a final drying shrinkage strain value at a temperature of 80 ° C. (ε _{sh). ∞80} ) (× 10 ⁻⁶ ) is approximated by a linear expression to determine the relational expression, and an early evaluation method for drying shrinkage strain of concrete.   In the early evaluation method for drying shrinkage strain of concrete according to claim 1 or 3, the separately determined relational expression is different between high fluid concrete and medium fluid concrete and other ordinary concrete. An early evaluation method for drying shrinkage strain of concrete.   6. An early evaluation method for drying shrinkage strain of concrete according to claim 1, 3 or 5, wherein the arbitrary long drying period is a drying period of 6 months.   5. The early evaluation method of drying shrinkage strain of concrete according to claim 2 or 4, wherein the relational expression is constructed separately when the concrete is high fluid concrete and medium fluid concrete and other ordinary concrete. A method for early evaluation of drying shrinkage strain of concrete.

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