CN111983200A - Early-age concrete strength determination method - Google Patents

Early-age concrete strength determination method Download PDF

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Publication number
CN111983200A
CN111983200A CN202010762311.7A CN202010762311A CN111983200A CN 111983200 A CN111983200 A CN 111983200A CN 202010762311 A CN202010762311 A CN 202010762311A CN 111983200 A CN111983200 A CN 111983200A
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concrete
strength
maturity
early
age
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张卫星
刘骅
胡小红
詹炳根
杨承春
夏长银
姚磊
刘庆红
饶凡
贾建胜
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China Energy Engineering Group Technology Development Co ltd
China Energy Construction Group Anhui Power Construction Second Engineering Co ltd
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China Energy Engineering Group Technology Development Co ltd
China Energy Construction Group Anhui Power Construction Second Engineering Co ltd
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/38Concrete; Lime; Mortar; Gypsum; Bricks; Ceramics; Glass
    • G01N33/383Concrete or cement
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B28WORKING CEMENT, CLAY, OR STONE
    • B28BSHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B11/00Apparatus or processes for treating or working the shaped or preshaped articles
    • B28B11/24Apparatus or processes for treating or working the shaped or preshaped articles for curing, setting or hardening
    • B28B11/245Curing concrete articles
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress

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Abstract

The invention discloses a method for determining the strength of early-age concrete, which comprises the following steps: s1, manufacturing a plurality of concrete test pieces, and curing the concrete test pieces under natural conditions and/or standard conditions; s2, measuring the strength of the concrete sample at different time points; s3, acquiring the maturity of early concrete at different time nodes; s4, suggesting corresponding parameters of the concrete maturity and the concrete strength according to the concrete strength of different time nodes and the concrete maturity of different time nodes; s5, performing formula fitting according to the corresponding generation of the concrete strength and the concrete maturity of different time nodes to obtain a calculation formula of the concrete strength and the concrete maturity.

Description

Early-age concrete strength determination method
Technical Field
The invention relates to a concrete strength determination method, in particular to a method for determining the strength of early-age concrete.
Background
As an indispensable material in the construction process of building engineering, the economical efficiency and the applicability of concrete materials are incomparable with those of other materials at the present stage and in a long time in the future.
After the concrete structure is poured, a certain strength is achieved, and the formwork can be detached. The method mainly determines when the concrete test block can be disassembled through the strength of the concrete test block cured under the same condition, and the template disassembling date, although the formula for calculating the concrete strength through the maturity is available at present, the existing formula can generate larger errors when calculating the concrete strength of early age, so that the concrete strength of the early age cannot be accurately calculated.
Disclosure of Invention
The present invention is directed to a method for determining the strength of early-age concrete, which solves the above-mentioned problems of the background art.
In order to achieve the purpose, the invention provides the following technical scheme:
a method for determining the strength of early-age concrete comprises the following steps:
s1, manufacturing a plurality of concrete test pieces, and curing the concrete test pieces under natural conditions and/or standard conditions;
s2, setting a measuring time interval, and measuring the strength of the concrete sample at different time points according to the measuring time interval;
s3, obtaining the maturity of the early-age concrete at different time nodes according to the measurement of S2, wherein the maturity is calculated by the following formula: m ═ Σ Ki (T)i+10)Δt;
S4, suggesting corresponding parameters of the concrete maturity and the concrete strength according to the concrete strength of different time nodes and the concrete maturity of different time nodes;
s5, performing formula fitting according to the corresponding generation of the concrete strength and the concrete maturity of different time nodes to obtain a calculation formula of the concrete strength and the concrete maturity, wherein the calculation formula is
Figure BDA0002613414040000011
Wherein M is the maturity of the concrete test piece; ki is a temperature influence coefficient; t isiIs the temperature at time i; Δ t is the sampling interval time; the concrete sample strength is obtained; a. b and c are coefficients.
As a further scheme of the invention: and the calculation formula of the concrete strength and the concrete maturity obtained in the step S5 is verified at least once, if the calculation formula strength and the verified measured strength are within an error range, the formula is determined to meet the composite requirement, and if the calculation formula strength and the verified measured strength exceed the error range, the steps S1-S5 are repeated.
As a further scheme of the invention: the concrete test pieces include 14 concrete test pieces.
As a further scheme of the invention: the measurement time interval is two or four hours.
As a further scheme of the invention: the concrete grade or the proportion of the concrete test piece in the S1 is the application range of the calculation formula of the concrete strength and the concrete maturity in the S5.
As a further scheme of the invention: and when the concrete test piece strength of any time node is tested, taking out the concrete test piece from the curing environment 15 minutes in advance, and measuring the concrete strength of the time node according to the compression strength test method.
As a further scheme of the invention: and the temperature of the concrete test piece is measured by a temperature sensor arranged in the concrete test piece.
As a further scheme of the invention: when the concrete specimen adopts C30, the coefficients a-29.80229, b-1579.00216 and C-26.325 are obtained.
As a further scheme of the invention: when the concrete specimen adopts C40, the coefficients a-50.95736, b-677.98081 and C-34.76842 are obtained.
Compared with the prior art, the invention has the beneficial effects that: according to the method, the early-age concrete is cured under different curing conditions, the temperature of the concrete and the strength of the concrete are measured at different time points or ages of the concrete being cured, then a concrete time, temperature and strength parameter table is established, then the maturity of the concrete is introduced, the maturity of the concrete is calculated according to the time and the temperature of the concrete, an accurate concrete strength calculation formula is obtained by fitting according to the maturity and the strength data, and meanwhile, the accuracy of the concrete strength calculation formula is ensured through verification.
Drawings
FIG. 1 is a table of temperature-intensity measurements for example 1 of the present application;
FIG. 2 is a table of maturity-intensity data for example 1 of the present application;
FIG. 3 is a table of verification data for example 1 of the present application;
FIG. 4 is a table of maturity-intensity data for example 2 of the present application;
FIG. 5 is a table of verification data for example 2 of the present application;
FIG. 6 is a table of temperature coefficient of influence selections according to the present application.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the embodiment of the invention, the method for determining the strength of early-age concrete comprises the following steps:
s1, manufacturing a plurality of concrete test pieces, and curing the concrete test pieces under natural conditions and/or standard conditions;
s2, setting a measuring time interval, and measuring the strength of the concrete sample at different time points according to the measuring time interval;
s3, obtaining the maturity of the early-age concrete at different time nodes according to the measurement of S2, wherein the maturity is calculated by the following formula: m ═ Σ Ki (T)i+10)Δt;
S4, suggesting corresponding parameters of the concrete maturity and the concrete strength according to the concrete strength of different time nodes and the concrete maturity of different time nodes;
s5, performing formula fitting according to the corresponding generation of the concrete strength and the concrete maturity of different time nodes to obtain a calculation formula of the concrete strength and the concrete maturity, wherein the calculation formula is
Figure BDA0002613414040000031
The concrete grade or the proportion of the concrete test piece in the S1 is the application range of the calculation formula of the concrete strength and the concrete maturity in the S5.
Wherein M is the maturity of the concrete test piece; ki is a temperature influence coefficient; t isiIs the temperature at time i; Δ t is the sampling interval time; the concrete sample strength is obtained; a. b and c are coefficients.
And S5, verifying the concrete strength and the concrete maturity calculation formula at least once, if the calculated strength and the verified measured strength of the formula are within an error range, determining that the formula meets the composite requirements, and if the calculated strength and the verified measured strength exceed the error range, repeating S1-S5.
And when the concrete test piece strength of any time node is tested, taking out the concrete test piece from the curing environment 15 minutes in advance, and measuring the concrete strength of the time node according to the compression strength test method.
Example 1
Manufacturing two groups of concrete test pieces, wherein concrete of a C40 standard grade is selected as the concrete, 15 concrete test pieces are arranged in each group, a temperature sensor is installed in each concrete test piece and used for measuring the temperature of the concrete test piece, the two groups of concrete test pieces are respectively maintained under standard conditions and natural conditions, the concrete test piece is molded and timed, the temperature and the compressive strength are measured for the first time at the 12 th hour, and then the temperature and the compressive strength are measured and recorded every 4 hours, specifically shown in the attached figure 1.
Then, according to the calculation formula of the maturity, M ═ Sigma Ki (T) is obtainedi+10) calculating the maturity of the concrete test piece on the corresponding time node by delta t, selecting a table according to the temperature influence coefficient Ki, wherein the temperature influence coefficient Ki under standard curing is 1, the environmental position under natural curing is 30 ℃, the temperature influence coefficient Ki under natural curing is 1.15, calculating the maturity of each time node of the standard curing and the natural curing and summarizing the maturity with corresponding compressive strength, as shown in figure 2.
The parameters in the attached figure 2 are input into a calculation formula of concrete strength and concrete maturity
Figure BDA0002613414040000041
The coefficients a-50.95736, b-677.98081 and C-34.76842 are obtained by data fitting, and the technical formula of the concrete strength and the concrete maturity under the C40 mark can be obtained
Figure BDA0002613414040000042
The obtained technical formula of the concrete strength and the concrete maturity is verified, and the concrete early strength value obtained according to the relation of the concrete maturity and the compressive strength of C40 and the early strength values of natural curing and standard curing are verified accurately, as shown in figure 3, as can be seen from the table in figure 3, the maximum error between the calculated strength and the actually measured strength is 5.7%, and it can be obtained that the technical formula relation of the concrete strength and the concrete maturity obtained in the embodiment meets the monitoring requirement of the concrete early strength.
Example 2
Two groups of concrete samples are manufactured, concrete with the C30 mark is selected as concrete, the rest steps are the same as those of the embodiment 1, and the obtained maturity and the compressive strength of the concrete are collected and finished, and are specifically shown in the attached figure 4.
The parameters in the attached figure 4 are input into the calculation formula of the concrete strength and the concrete maturity
Figure BDA0002613414040000043
The coefficients a-29.80229, b-1579.00216 and C-26.325 are obtained by data fitting, and the technical formula of the concrete strength and the concrete maturity under the C30 mark can be obtained
Figure BDA0002613414040000051
The obtained technical formula of the concrete strength and the concrete maturity is verified, and the accuracy of the concrete early strength value obtained according to the relation of the concrete maturity and the compressive strength of C30 and the early strength values of natural curing and standard curing is verified, as shown in figure 5, as can be seen from the table in figure 5, the maximum error between the calculated strength and the actually measured strength is 6.61%, and it can be obtained that the technical formula relation of the concrete strength and the concrete maturity obtained in the embodiment meets the monitoring requirement of the concrete early strength.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (9)

1. A method for determining the strength of early-age concrete is characterized by comprising the following steps:
s1, manufacturing a plurality of concrete test pieces, and curing the concrete test pieces under natural conditions and/or standard conditions;
s2, setting a measuring time interval, and measuring the strength of the concrete sample at different time points according to the measuring time interval;
s3, obtaining the maturity of the early-age concrete at different time nodes according to the measurement of S2, wherein the maturity is calculated by the following formula: m ═ Σ Ki (T)i+10)Δt;
S4, suggesting corresponding parameters of the concrete maturity and the concrete strength according to the concrete strength of different time nodes and the concrete maturity of different time nodes;
s5, performing formula fitting according to the corresponding generation of the concrete strength and the concrete maturity of different time nodes to obtain a calculation formula of the concrete strength and the concrete maturity, wherein the calculation formula is
Figure FDA0002613414030000011
Wherein M is the maturity of the concrete test piece; ki is a temperature influence coefficient; t isiIs the temperature at time i;Δ t is the sampling interval time; the concrete sample strength is obtained; a. b and c are coefficients.
2. The method for determining early age concrete strength according to claim 1, wherein the concrete strength and concrete maturity calculation formula obtained in step S5 is verified at least once, if the calculated strength and the verified measured strength of the formula are within an error range, the formula is determined to be a composite requirement, and if the calculated strength and the verified measured strength of the formula are within the error range, steps S1-S5 are repeated.
3. The method of claim 1, wherein the concrete samples comprise 14 concrete samples.
4. A method of determining early age concrete strength as claimed in claim 1, wherein said measurement time interval is two or four hours.
5. The method for determining the early age concrete strength according to claim 1, wherein the concrete grade or the concrete mixture ratio of the concrete sample in the S1 is the application range of the calculation formula of the concrete strength and the concrete maturity in the S5.
6. The method for determining the strength of early-age concrete according to claim 1, wherein when the strength of the concrete sample at any time node is tested, the concrete sample is taken out of the curing environment 15 minutes ahead, and the concrete strength at the time node is determined according to a compressive strength test method.
7. The method for determining early age concrete strength according to claim 1, wherein the temperature of the concrete sample is measured by a temperature sensor disposed in the concrete sample.
8. The method for determining the early-age concrete strength of claim 1, wherein when C30 is adopted by the concrete sample, the coefficients a-29.80229, b-1579.00216 and C-26.325 are obtained.
9. The method for determining the early-age concrete strength of claim 1, wherein when C40 is adopted by the concrete sample, the coefficients a-50.95736, b-677.98081 and C-34.76842 are obtained.
CN202010762311.7A 2020-07-31 2020-07-31 Early-age concrete strength determination method Pending CN111983200A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113834742A (en) * 2021-10-25 2021-12-24 北京建筑大学 Method for determining open traffic strength of polyurethane concrete
CN116572381A (en) * 2023-07-13 2023-08-11 四川公路桥梁建设集团有限公司 Prefabricated concrete member production regulation and control system and method

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113834742A (en) * 2021-10-25 2021-12-24 北京建筑大学 Method for determining open traffic strength of polyurethane concrete
CN113834742B (en) * 2021-10-25 2023-07-21 北京建筑大学 Method for determining open traffic intensity of polyurethane concrete
CN116572381A (en) * 2023-07-13 2023-08-11 四川公路桥梁建设集团有限公司 Prefabricated concrete member production regulation and control system and method
CN116572381B (en) * 2023-07-13 2023-10-31 四川公路桥梁建设集团有限公司 Prefabricated concrete member production regulation and control system and method

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