CN114654576A - Method for quickly optimizing mix proportion of precast concrete components - Google Patents

Method for quickly optimizing mix proportion of precast concrete components Download PDF

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CN114654576A
CN114654576A CN202210462383.9A CN202210462383A CN114654576A CN 114654576 A CN114654576 A CN 114654576A CN 202210462383 A CN202210462383 A CN 202210462383A CN 114654576 A CN114654576 A CN 114654576A
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concrete
curing
rapid
maintenance
temperature
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高原
冯良平
任京华
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CCCC Highway Long Bridge Construction National Engineering Research Center Co Ltd
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CCCC Highway Long Bridge Construction National Engineering Research Center Co Ltd
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Priority to PCT/CN2022/095592 priority patent/WO2023206692A1/en
Publication of CN114654576A publication Critical patent/CN114654576A/en
Priority to CN202310194454.6A priority patent/CN116079879A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B11/00—Apparatus or processes for treating or working the shaped or preshaped articles
    • B28B11/24—Apparatus or processes for treating or working the shaped or preshaped articles for curing, setting or hardening
    • B28B11/245—Curing concrete articles
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/91—Use of waste materials as fillers for mortars or concrete

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Abstract

The utility model relates to a precast concrete technical field provides a method of quick optimization precast concrete component mix proportion, includes: determining the concrete 28d design strength required by the concrete prefabricated part and the concrete design strength after the rapid prefabrication and maintenance are finished; the method comprises the following steps of (1) predetermining the mixing proportion of concrete, and preparing two groups of concrete test pieces according to the mixing proportion; and curing the concrete sample by adopting an actual rapid prefabrication curing method and a constant-temperature rapid curing method, measuring the strength of the concrete sample by adopting a standard test method after curing is finished, and comparing the measured strength with the strength required by design until the strength meets the requirement. By utilizing the method, the trial-matching times of the concrete mix proportion can be obviously reduced, the production progress of the prefabricated part is accelerated, the trial-matching period of the concrete is greatly shortened, the problem that the optimization period of the mix proportion of the traditional concrete prefabricated part is long is solved, the dependence of the concrete mix proportion adjustment on engineering experience is reduced, and the method has better scientific instructive performance and popularization value.

Description

Method for quickly optimizing mix proportion of precast concrete components
Technical Field
The disclosure relates to the technical field of precast concrete, in particular to a method for quickly optimizing the mix proportion of precast concrete components.
Background
The precast concrete technology is one of important technologies for practicing a green low-carbon idea and realizing bridge industrialization, and the rapid curing processes such as steam curing and the like are core means of the precast concrete technology. The rapid maintenance is beneficial to improving the turnover rate of the die, improving the utilization rate and labor productivity of main process equipment, shortening the production period and reducing the product cost.
In the design and adjustment process of the mix proportion of the factory-like precast concrete members, the compressive strength of the concrete after standard maintenance for 28d is still the key quality parameter and acceptance criterion for evaluating the qualification of the concrete members. However, the test method for standard curing 28d strength is not capable of designing and adjusting the concrete mixing ratio in time and predicting the quality condition of the prefabricated parts in production and preparation in time due to the long test period.
In addition, the existing research method for optimizing the mix proportion of the concrete mainly focuses on the traditional orthogonal design test method, the method has more limit conditions, the experimental search range is limited, the research is long in time consumption and high in cost, and an ideal and close to actual mix proportion optimization result cannot be obtained.
Therefore, there is a need to develop a scientific and rapid method for optimizing the mix ratio of precast concrete members.
Disclosure of Invention
Technical problem to be solved
In view of this, the main objective of the present disclosure is to provide a method for quickly optimizing the mix ratio of precast concrete components, so as to solve the problem that the mix ratio optimization period of the traditional precast concrete components is long, and reduce the dependency of the mix ratio adjustment on the engineering experience.
(II) technical scheme
In order to achieve the above objects, the present disclosure provides a method for rapidly optimizing a mix ratio of precast concrete members, the method comprising:
determining the concrete 28d design strength sigma required by the concrete prefabricated part28And the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2And determining the maturity S of the concrete at the end of the standard concrete curing 28d28；
The method comprises the following steps of (1) predetermining the mixing proportion of concrete, and preparing two groups of concrete test pieces according to the mixing proportion;
adopts an actual rapid prefabrication maintenance modeCuring one of the two groups of concrete test pieces, and determining to obtain the actual strength sigma 'of the concrete at the end of the rapid prefabrication curing't2；
Curing the other one of the two groups of concrete test pieces in a constant-temperature rapid curing mode, and determining to obtain the actual strength sigma 'of the concrete 28 d'28；
Judging actual strength sigma 'of concrete at the end of rapid prefabrication and maintenance't2Greater than the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2And concrete 28d actual strength sigma'28Greater than the design strength sigma of concrete 28d28Whether the two are simultaneously established or not, and if the two are simultaneously established, the requirements are met; otherwise, adjusting the mix proportion of the concrete, preparing two groups of concrete samples again according to the adjusted mix proportion for maintenance and determination until the actual strength sigma 'of the concrete at the end of the rapid prefabrication and maintenance't2Greater than the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2And concrete 28d actual strength sigma'28Greater than the design strength sigma of the concrete 28d28And at the same time.
In the above scheme, the concrete 28d design strength σ required to be achieved by the concrete prefabricated part is determined28And the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2Is determined according to the design index requirements of the concrete prefabricated part, and the maturity S of the concrete at the end of the standard concrete curing 28d is determined28The maturity S of the concrete is determined under the conditions that the curing temperature is 20 ℃ and the relative humidity is more than 95 percent28。
In the above scheme, the predetermined mix proportion of the concrete is determined according to a design rule related to the mix proportion of the concrete.
In the scheme, a group of test pieces in the two groups of concrete test pieces are maintained by adopting an actual rapid prefabrication maintenance mode, and the actual strength sigma 'of the concrete after the rapid prefabrication maintenance is determined't2The method comprises the following steps: maintaining one of the two groups of concrete samples according to the actual rapid prefabrication and maintenance system requirement in the production process of the concrete prefabricated part, and adopting a standard after the maintenance is finishedThe quasi test method is used for measuring the strength of the test piece, and the measured strength is the actual strength sigma 'of the concrete at the end of rapid prefabrication and curing't2。
In the scheme, the actual rapid prefabrication maintenance system is determined by a maintenance process for prefabricated part production and preparation, and the maintenance parameters at least comprise the standing time duration t1Static temperature T1Temperature rising rate v1Duration of constant temperature t2Constant temperature T2And a temperature reduction rate v2And a total time t for rapid maintenance3。
In the scheme, the other one of the two groups of concrete test pieces is maintained in a constant-temperature rapid maintenance mode, and the actual strength sigma 'of the concrete 28d is measured'28The method comprises the following steps: curing the other one of the two groups of concrete test pieces in a constant-temperature rapid curing manner, and measuring the strength of the test piece by adopting a standard test method after curing is finished, wherein the measured strength is the actual strength sigma 'of the concrete 28 d'28。
In the above scheme, in the constant-temperature rapid maintenance mode, the temperature for maintenance is selected according to laboratory conditions, and the age t of maintenance is selectedqIs the maturity S of the concrete at the end of the standard curing 28d28Obtained by reverse thrust.
In the scheme, the selection range of the temperature required for curing in the constant-temperature rapid curing mode is 40-75 ℃.
In the scheme, the maturity degree of the concrete adopts the equivalent age teqAnd characterizing, wherein the equivalent age calculation formula is as follows:
Figure BDA0003620672130000031
wherein:
UaT＝(43830-43T)e(-0.0017T)t
in the formula: r is a gas constant, and 8.314J/mol.K is taken; u shapearThe activation energy of the hydration reaction of the cement is the standard curing temperature; u shapeaTThe activation energy of the reaction at the temperature T is time and temperatureA function.
In the scheme, the mixing proportion of the concrete is adjusted, and at least one of a group consisting of selecting cement with high grade, reducing the water-cement ratio, improving the grain composition of coarse and fine aggregates, and doping high-efficiency active mineral materials or high-efficiency water reducing agents is adopted.
(III) advantageous effects
According to the technical scheme, compared with the traditional method for optimally designing the mix proportion of the precast concrete components, the method for rapidly optimizing the mix proportion of the precast concrete components can obviously reduce the trial-mix times of the mix proportion of the concrete, quicken the production progress of the precast components, greatly shorten the trial-mix period of the concrete, solve the problem of long optimized mix proportion period of the traditional precast concrete components, save time, save cost, reduce the dependence of the adjustment of the mix proportion of the concrete on engineering experience, and have better scientific guidance and popularization value.
Drawings
The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments of the present disclosure with reference to the accompanying drawings, in which:
fig. 1 is a flowchart of a method for rapidly optimizing the mix ratio of precast concrete members provided by the present disclosure.
Fig. 2 is a flow chart of a method for rapidly optimizing the mix ratio of precast concrete components according to an embodiment of the present disclosure.
FIG. 3 is a schematic diagram of curing one of the two sets of concrete test pieces by using an actual rapid prefabrication curing method according to an embodiment of the disclosure.
Fig. 4 is a comparison graph of a method for rapidly optimizing the mix ratio of precast concrete members using an embodiment of the present disclosure and a conventional mix ratio optimization method.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is illustrative only and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure.
The embodiment of the disclosure provides a method for rapidly optimizing the mix proportion of precast concrete components. As shown in fig. 1, fig. 1 is a flowchart of a method for rapidly optimizing the mix ratio of precast concrete members according to the present disclosure. It should be noted that fig. 1 is only an example of an application scenario in which the embodiments of the present disclosure may be applied to help those skilled in the art understand the technical content of the present disclosure, but does not mean that the embodiments of the present disclosure may not be used in other environments or scenarios.
As shown in fig. 1, the method for rapidly optimizing the mix ratio of precast concrete components provided by the present disclosure includes the following steps:
step S1: determining the concrete 28d design strength sigma required by the concrete prefabricated part28And the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2And determining the maturity S of the concrete at the end of the standard concrete curing 28d28；
In the step, the design strength sigma of the concrete 28d required by the concrete prefabricated part is determined according to the design index requirement of the concrete prefabricated part28And the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2. Determining the maturity S of the concrete at the end of the standard concrete curing 28d28Is determined under the conditions that the curing temperature is 20 ℃ and the relative humidity is more than 95 percent.
Step S2: the method comprises the following steps of (1) predetermining the mixing proportion of concrete, and preparing two groups of concrete test pieces according to the mixing proportion;
in the step, according to the design rule related to the concrete mixing ratio, the mixing ratio of the concrete is firstly predetermined, and then two groups of concrete test pieces are prepared according to the mixing ratio.
Step S3: curing one of the two groups of concrete test pieces by adopting an actual rapid prefabrication and curing mode, and determining to obtain the concrete when the rapid prefabrication and curing are finishedActual strength sigma 'of concrete't2；
In the step, one of the two groups of concrete test pieces is maintained according to the requirements of an actual rapid prefabrication maintenance system in the production process of the precast concrete component, the strength of the test piece is measured by adopting a standard test method after the maintenance is finished, and the measured strength is the actual concrete strength sigma 'at the end of rapid prefabrication maintenance't2. Wherein the actual rapid prefabricating and curing system is determined by the curing process for the production and preparation of prefabricated parts and at least comprises a static time duration t1Static temperature T1Temperature rising rate v1Duration of constant temperature t2Constant temperature T2Cooling rate v2And total time t of rapid curing3And waiting for curing parameters.
Step S4: curing the other one of the two groups of concrete test pieces in a constant-temperature rapid curing mode, and determining to obtain the actual strength sigma 'of the concrete 28 d'28；
In the step, the other group of the two groups of concrete test pieces are maintained in a constant-temperature rapid maintenance mode, the strength of the test piece is measured by adopting a standard test method after maintenance is finished, and the measured strength is 28d actual strength sigma 'of the concrete'28. In the constant temperature rapid curing mode, the temperature for curing is selected according to laboratory conditions, and the selection range of the temperature for curing is generally 40-75 ℃. Age t of required maintenanceqAccording to the maturity S of the concrete at the end of the standard maintenance 28d in the step S128Obtained by reverse thrust.
In this embodiment, the maturity of the concrete adopts an equivalent age teqAnd characterizing, wherein the equivalent age calculation formula is as follows:
Figure BDA0003620672130000051
in equation 1:
UaT＝(43830-43T)e(-0.0017T)t
wherein: r is a gas constant, and 8.314J/mol.K is taken; u shapearThe activation energy of the hydration reaction of the cement is the standard curing temperature; u shapeaTThe activation energy of the reaction at temperature T is a function of time and temperature.
Step S5: judging actual strength sigma 'of concrete at the end of rapid prefabrication and maintenance't2Greater than the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2And concrete 28d actual strength sigma'28Greater than the design strength sigma of concrete 28d28Whether the two processes are simultaneously established or not, if so, the requirements are met, and the process is ended; otherwise, returning to the step S2 to adjust the mix proportion of the concrete, preparing two groups of concrete samples again according to the adjusted mix proportion, and then executing the steps S3 to S5 to carry out maintenance and measurement on the two groups of prepared concrete samples until the actual strength sigma 'of the concrete at the end of the rapid prefabrication maintenance't2Greater than the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2And concrete 28d actual strength sigma'28Greater than the design strength sigma of concrete 28d28And at the same time.
In the step, the mixing proportion of the concrete is adjusted, and at least one of the group consisting of selecting cement with high grade, reducing the water-cement ratio, improving the grain composition of coarse and fine aggregates, and doping high-efficiency active mineral materials or high-efficiency water reducing agents is adopted.
Example 1
Referring to fig. 2, fig. 2 is a flowchart of a method for rapidly optimizing the mix ratio of precast concrete components according to an embodiment of the present disclosure, including the following steps:
firstly, determining the concrete 28d design strength sigma required by the concrete prefabricated part according to the design index requirement of the concrete prefabricated part28And the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2。
② determining the maturity S of the concrete when the standard curing of the concrete (curing temperature is 20 ℃, relative humidity is more than 95%) is finished for 28d28。
Thirdly, according to the related design rules of the concrete mixing proportion, the concrete mixing proportion is predetermined, and then two groups of concrete test pieces are prepared according to the mixing proportion.
Fourthly, curing one of the two groups of concrete test pieces prepared in the third step according to an actual rapid prefabrication and curing mode in the production process of the concrete prefabricated part, determining the strength of the test piece by adopting a standard test method after curing is finished, and determining the strength as the actual strength sigma 'of the concrete when the rapid prefabrication and curing is finished't2. The actual rapid prefabrication maintenance mode is determined by the maintenance process of prefabricated part production and preparation, and comprises the standing time duration t1Static temperature T1Temperature rising rate v1Duration of constant temperature t2Constant temperature T2Cooling rate v2And total time t of rapid curing2And the like.
Fifthly, curing the other concrete test piece in the two groups of concrete test pieces prepared in the third step in a constant-temperature rapid curing mode, and measuring the strength of the test piece by adopting a standard test method after curing is finished, wherein the measured strength is 28d actual strength sigma 'of the concrete'28. The determination mode of the constant-temperature rapid maintenance mode comprises the following steps: firstly, selecting the temperature of a constant-temperature rapid curing system according to laboratory conditions, wherein the temperature of the constant-temperature rapid curing system is selected within the range of 40-75 ℃; then according to the step II, the maturity S of the concrete28Obtaining the age t of the required maintenance under the constant temperature quick maintenance condition by reverse pushingq。
Sixth, the actual strength sigma of the concrete at the end of the rapid prefabrication and maintenance is judged't2Greater than the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2And concrete 28d actual strength sigma'28Greater than the design strength sigma of concrete 28d28Whether the two are simultaneously established or not, and if the two are simultaneously established, the requirements are met; otherwise, namely the actual strength sigma 'of the concrete at the end of the rapid prefabrication and maintenance't2And concrete 28d actual strength sigma'28Not simultaneously greater than the design strength sigma of the concrete at the end of rapid prefabrication and maintenancet2And concrete 28d design Strength σ28Adjusting the concrete mixing proportion in the third step, and repeating the third step and the sixth step until the requirements are met.
Further, in the second step, the maturity degree of the concrete adopts an equivalent age teqCharacterization of said equivalent ageThe calculation formula is as follows:
Figure BDA0003620672130000071
wherein:
UaT＝(43830-43T)e(-0.0017T)t
in the formula: r is a gas constant, and 8.314J/mol.K is taken; u shapearThe activation energy of the hydration reaction of the cement is the standard curing temperature; u shapeaTThe activation energy of the reaction at temperature T is a function of time and temperature.
Further, in the step sixthly, the concrete mixing proportion adjusting method comprises one or any combination of the following methods: (1) selecting cement with high grade; (2) the water-gel ratio is reduced; (3) improving the grain composition of coarse and fine aggregates; (4) doping high-efficiency active mineral ginseng material; (5) and (4) doping a high-efficiency water reducing agent.
Example 2
Referring to fig. 2, fig. 2 is a flowchart of a method for rapidly optimizing the mix ratio of precast concrete components according to an embodiment of the present disclosure, including the following steps:
the method comprises the following steps: the concrete precast box girder of C50 is produced and prepared in a certain project, and the 28d design strength sigma is required according to the design index of the concrete precast member2850MPa, the strength sigma required to be reached at the end of rapid prefabrication and maintenancet2The pressure was 37.5 MPa.
Step two: determining the maturity S of the concrete at the end of the standard curing (curing temperature 20 ℃, relative humidity more than 95%) 28d28＝672h。
Step three: determining the mixing proportion of the concrete according to the design rule of common concrete mixing proportion (JGJ 55-2011), and preparing two groups of test pieces according to the test method standard of concrete physical and mechanical properties GB/T50081-2019, wherein the mixing proportion of the concrete is as follows:
Figure BDA0003620672130000081
step four: an actual rapid prefabrication maintenance system is obtained according to a maintenance process for producing and preparing prefabricated parts, and is shown in figure 3, wherein the standing time is 12 hours, the standing temperature is 20 ℃, the heating rate is 10 ℃/h, the constant temperature is 50 ℃, the constant temperature duration is 24 hours, the cooling rate is 5 ℃/h, and the total rapid maintenance duration is 45 hours. Curing the first group of test pieces obtained in the third step according to the requirements of the curing system, determining the strength of the test pieces by adopting a standard test method after curing is finished, wherein the determined strength is the actual strength sigma 'of the concrete at the end of actual rapid prefabrication and curing't2＝50.5MPa。
Step five: determining the temperature of the constant-temperature rapid curing system to be 70 ℃ according to the laboratory conditions, and determining the maturity S of the concrete according to the step two28Obtaining the age t of the required maintenance under the constant-temperature quick maintenance condition by adopting a formula (1) through reverse calculation q75 h. Curing the second group of test pieces in the step three in the constant-temperature rapid curing mode, and measuring the strength of the test pieces by adopting a standard test method after curing is finished, wherein the measured strength is the actual strength sigma 'of the concrete 28 d'28＝63.4MPa。
Step six: concrete actual strength sigma 'at the end of rapid prefabrication and maintenance't2And 28d actual Strength σ'28Simultaneously is greater than the strength sigma of the design requirement at the end of the rapid prefabrication maintenancet2And 28d design Strength σ28And explaining that the mixing ratio of the third step meets the design requirement of the prefabricated part, and taking the mixing ratio determined in the third step as the final mixing ratio, as can be seen from fig. 4, by the method for quickly optimizing the mixing ratio of the prefabricated concrete part provided by the embodiment of the disclosure, the mixing ratio optimization cycle of the concrete prefabricated part is only 75 hours, compared with the traditional mixing ratio optimization method, the mixing ratio design adjustment cycle is greatly reduced, and the aim of shortening the construction period of the prefabricated part is further fulfilled.
Example 3
Referring to fig. 2, fig. 2 is a flowchart of a method for rapidly optimizing a mix ratio of precast concrete components according to an embodiment of the present disclosure, which is substantially the same as the method of embodiment 2 except that: concrete after finishing quick prefabrication and maintenance in the sixth stepActual strength sigma't2And concrete 28d actual strength sigma'28Not simultaneously greater than the designed strength sigma of the concrete at the end of the rapid precast curingt2And concrete 28d design Strength σ28Explaining that the concrete mixing proportion in the third step does not meet the design requirement of the prefabricated part, the concrete mixing proportion needs to be adjusted, and specifically, when the concrete mixing proportion is adjusted, the concrete mixing proportion comprises the following one or any combination of several modes: (1) selecting cement with high grade; (2) the water-gel ratio is reduced; (3) improving the grain composition of coarse and fine aggregates; (4) doping high-efficiency active mineral ginseng material; (5) and (4) doping a high-efficiency water reducing agent.
For the embodiment, the method specifically includes the following steps:
the method comprises the following steps: the concrete precast box girder of C50 is produced and prepared in a certain project, and the 28d design strength sigma is required according to the design index of the concrete precast member2850MPa, the strength sigma required to be reached when the rapid prefabrication curing is finishedt2Is 37.5 MPa.
Step two: determining the maturity S of the concrete at the end of 28 days of standard curing (curing temperature 20 ℃, relative humidity more than 95 percent)28＝672h。
Step three: determining the mixing proportion of the concrete according to the design rule of common concrete mixing proportion (JGJ 55-2011), and preparing two groups of test pieces according to the test method standard of concrete physical and mechanical properties GB/T50081-2019, wherein the mixing proportion of the concrete is as follows:
Figure BDA0003620672130000091
step four: an actual rapid prefabrication maintenance system is obtained according to a maintenance process for producing and preparing prefabricated parts, and is shown in figure 3, wherein the standing time is 12 hours, the standing temperature is 20 ℃, the heating rate is 10 ℃/h, the constant temperature is 50 ℃, the constant temperature duration is 24 hours, the cooling rate is 5 ℃/h, and the total rapid maintenance duration is 45 hours. Curing the first group of test pieces obtained in the third step according to the requirements of the curing system, and measuring the strength of the test pieces by adopting a standard test method after the curing is finished, wherein the measured strength is concreteActual strength sigma 'at end of actual rapid prefabrication and maintenance't2＝38.8MPa。
Step five: determining the temperature of the constant-temperature rapid curing system to be 70 ℃ according to the laboratory conditions, and determining the maturity S of the concrete according to the step two28Obtaining the age t of the required maintenance under the constant-temperature quick maintenance condition by adopting a formula (1) through reverse calculation q75 h. Curing the second group of test pieces in the step three in the constant-temperature rapid curing mode, and measuring the strength of the test pieces by adopting a standard test method after curing is finished, wherein the measured strength is the actual strength sigma 'of the concrete 28 d'28＝48.3MPa。
Step six: concrete actual strength sigma 'at the end of rapid prefabrication and maintenance't2Intensity σ greater than design requirement t228d actual Strength σ'28Design strength σ of less than 28d28The mixing ratio of the step three needs to be adjusted and optimized.
Repeating the third step, reducing the water-cement ratio by properly reducing the unit water consumption of the concrete, and optimally adjusting the first concrete mixing ratio, wherein the adjusted concrete mixing ratio is as follows:
Figure BDA0003620672130000101
repeating the step four, wherein the measured strength is the actual strength sigma 'of the concrete at the end of actual rapid prefabrication and maintenance't2＝43.5MPa。
And step five is repeated, and the measured strength is the actual strength sigma 'of the concrete 28 d'28＝58MPa。
And step six is repeated, the actual strength sigma 'of the concrete at the end of the rapid prefabrication and maintenance't2And 28d actual Strength σ'28Simultaneously is greater than the strength sigma of the design requirement at the end of the rapid prefabrication maintenancet2And 28d design Strength σ28The mixing ratio after adjustment satisfies the design requirements of the prefabricated part, and the mixing ratio after the second adjustment is taken as the final mixing ratio.
The above-mentioned embodiments, objects, technical solutions and advantages of the present disclosure are further described in detail, it should be understood that the above-mentioned embodiments are only examples of the present disclosure, and should not be construed as limiting the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.

Claims (10)

1. A method for rapidly optimizing the mix ratio of precast concrete components, comprising:
determining the concrete 28d design strength sigma required by the concrete prefabricated part28And the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2And determining the maturity S of the concrete at the end of the standard concrete curing 28d28；
The method comprises the following steps of (1) predetermining the mixing proportion of concrete, and preparing two groups of concrete test pieces according to the mixing proportion;
maintaining one group of test pieces in the two groups of concrete test pieces by adopting an actual rapid prefabrication maintenance mode, and determining to obtain actual concrete strength sigma 'after rapid prefabrication maintenance is finished't2；
Curing the other one of the two groups of concrete test pieces in a constant-temperature rapid curing mode, and determining to obtain the actual strength sigma 'of the concrete 28 d'28；
Judging actual strength sigma 'of concrete at the end of rapid prefabrication and maintenance't2Greater than the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2And concrete 28d actual strength sigma'28Greater than the design strength sigma of concrete 28d28Whether the two are simultaneously established or not, and if the two are simultaneously established, the requirements are met; otherwise, adjusting the mix proportion of the concrete, preparing two groups of concrete samples again according to the adjusted mix proportion for maintenance and determination until the actual strength sigma 'of the concrete at the end of the rapid prefabrication and maintenance't2Greater than the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2And concrete 28d actual strength sigma'28Greater than the design strength sigma of concrete 28d28And at the same time.
2.The method for rapidly optimizing the mix proportion of the precast concrete unit according to claim 1, wherein the concrete 28d design strength σ to be achieved by the precast concrete unit is determined28And the design strength sigma of the concrete at the end of the rapid prefabrication and maintenancet2Is determined according to the design index requirements of the concrete prefabricated part, and the maturity S of the concrete at the end of the standard concrete curing 28d is determined28The maturity S of the concrete is determined under the conditions that the curing temperature is 20 ℃ and the relative humidity is more than 95 percent28。
3. The method for rapidly optimizing the mix ratio of precast concrete units according to claim 1, wherein the mix ratio of the predetermined concrete is determined according to a design rule related to the mix ratio of the concrete.
4. The method for rapidly optimizing the mix proportion of the precast concrete members according to claim 1, wherein one of the two groups of concrete samples is cured by adopting an actual rapid precast curing manner, and the actual strength σ 'of the concrete at the end of the rapid precast curing is measured't2The method comprises the following steps:
curing one of the two groups of concrete test pieces according to the requirements of an actual rapid prefabrication and curing system in the production process of the concrete prefabricated part, determining the strength of the test piece by adopting a standard test method after the curing is finished, wherein the measured strength is the actual concrete strength sigma 'at the end of rapid prefabrication and curing't2。
5. The method for rapidly optimizing the mix proportion of precast concrete units according to claim 4, wherein the actual rapid precast maintenance schedule is determined by a maintenance process for the production and preparation of precast concrete units, and the maintenance parameters at least include the length of the rest time t1Static temperature T1Temperature rising rate v1Duration of constant temperature t2Constant temperature T2And a temperature reduction rate v2And total time t of rapid curing3。
6. The method for rapidly optimizing the mix proportion of the precast concrete components according to claim 1, wherein the other of the two groups of concrete test pieces is cured by adopting a constant-temperature rapid curing manner, and the actual strength σ 'of the concrete 28d is measured'28The method comprises the following steps:
curing the other one of the two groups of concrete test pieces in a constant-temperature rapid curing manner, determining the strength of the test piece by adopting a standard test method after the curing is finished, wherein the determined strength is the actual strength sigma 'of the concrete 28 d'28。
7. The method for rapidly optimizing the mix ratio of precast concrete components according to claim 6, wherein in the constant temperature rapid curing mode, the temperature of required curing is selected according to laboratory conditions, and the age t of required curingqIs according to the maturity S of the concrete at the end of standard curing 28d28Obtained by reverse thrust.
8. The method for rapidly optimizing the mix proportion of precast concrete members according to claim 7, wherein the curing temperature required in the constant temperature rapid curing manner is selected in the range of 40-75 ℃.
9. The method for rapidly optimizing the mix ratio of precast concrete units according to claim 7, wherein the maturity of the concrete adopts an equivalent age teqAnd characterizing, wherein the equivalent age calculation formula is as follows:
Figure FDA0003620672120000021
wherein:
UaT＝(43830-43T)e(-0.0017T)t
in the formula: r is a gas constant, and 8.314J/mol.K is taken; u shapearThe activation energy of the hydration reaction of the cement is the standard curing temperature; u shapeaTAt a temperature of TThe activation energy of the reaction is a function of time and temperature.
10. The method for rapidly optimizing the mix proportion of the precast concrete component according to claim 1, wherein the mix proportion of the concrete is adjusted by at least one of the group consisting of selecting cement with high grade, reducing the water-cement ratio, improving the grain composition of coarse and fine aggregates, adding highly active mineral materials or adding a high-efficiency water reducing agent.
CN202210462383.9A 2022-04-28 2022-04-28 Method for quickly optimizing mix proportion of precast concrete components Pending CN114654576A (en)

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