阅读说明：本技术 一种快速预测单掺粉煤灰轻骨料混凝土实际强度的方法 (Method for rapidly predicting actual strength of single-doped fly ash lightweight aggregate concrete ) 是由 朱然 占羿箭 朱毅敏 徐磊 黄玉林 徐俊 王圣怡 史晓婉 于 2020-07-24 设计创作，主要内容包括：本发明属于混凝土技术领域,特别涉及一种快速预测单掺粉煤灰轻骨料混凝土实际强度的方法,目的在于提供一种评估单掺粉煤灰轻骨料混凝土强度的简单有效手段。该方法以粉煤灰掺量、水胶比、水泥强度以及成熟度为自变量,建立显式快速预测单掺粉煤灰轻骨料混凝土抗压强度的强度计算模型,提供了一种评估单掺粉煤灰轻骨料混凝土强度的简单有效手段。该方法可以直接根据成熟度、水泥出厂报告中所给的28d抗压强度、配合比中的粉煤灰掺量以及水胶比快速预测单掺粉煤灰轻骨料混凝土强度。而且对于现场施工不便的条件下单掺粉煤灰轻骨料混凝土构件的强度预测提供了保障,同时也给现场施工人员提供了便利。(The invention belongs to the technical field of concrete, and particularly relates to a method for quickly predicting actual strength of single-doped fly ash lightweight aggregate concrete, aiming at providing a simple and effective means for evaluating the strength of the single-doped fly ash lightweight aggregate concrete. The method takes the fly ash mixing amount, the water-cement ratio, the cement strength and the maturity as independent variables, establishes an explicit strength calculation model for rapidly predicting the compressive strength of the single-doped fly ash lightweight aggregate concrete, and provides a simple and effective means for evaluating the strength of the single-doped fly ash lightweight aggregate concrete. The method can be used for rapidly predicting the strength of the singly-doped fly ash lightweight aggregate concrete directly according to the maturity, 28d compressive strength given in a cement delivery report, the fly ash mixing amount in the mixing proportion and the water-cement ratio. And the method provides guarantee for strength prediction of the single-doped fly ash lightweight aggregate concrete member under the condition of inconvenient field construction, and simultaneously provides convenience for field construction personnel.)

1. A method for rapidly predicting actual strength of a single-doped fly ash lightweight aggregate concrete is characterized by comprising the following steps:

s1, preparing a plurality of test blocks of the single-doped fly ash lightweight aggregate concrete with different doping amounts, placing the test blocks in groups at different curing temperatures for curing, testing the compressive strength at different ages, and providing a data basis for subsequently establishing a rapid testing formula for predicting the strength of the single-doped fly ash lightweight aggregate concrete;

s2, arranging a temperature sensor in the concrete test block with the single fly ash-doped lightweight aggregate, and uploading temperature data acquired by the temperature sensor to a processor; and (3) calculating the maturity value of the fly ash lightweight aggregate concrete in each age according to the data of each age and the maintenance temperature data by substituting into a formula (1):

M=∑(T-T ₀)·Δt(1)

in the formula:Mmaturity in degrees, unit DEG C·d；TIs a time interval deltatTemperature in concrete, unit ℃;T ₀the reference temperature is the temperature at which the concrete strength does not increase with the age, namely the temperature at which the hydration reaction in the concrete stops, and is usually-10 ℃; deltatIs a time interval, unitd；

Step S3, performing fitting analysis on the test strength data obtained in the step S1 and the maturity information obtained in the step S2, and establishing a strength development curve of the single-doped fly ash lightweight aggregate concrete according to a strength relational expression of the single-doped fly ash lightweight aggregate concrete obtained through the fitting analysis by using the acquired temperature, the known concrete mixing ratio and the material information, which is shown in a formula (2);

f _t =0.2632f _ce ·M·(0.0906R _FA ²+0.0253R _FA +0.9995)·(1/R _W/B -0.304)·(-0.797R _FA ²-0.359R _FA +1.426)/(0.9012M+76.3) (2)

in the formula:f _ce the cement is 28d compressive strength given in a cement factory report, and the unit is MPa;Mthe unit is the maturity of the fly ash lightweight aggregate concrete, and the unit is DEG C.d;R _FA the blending amount of the fly ash is taken as the blending amount of the fly ash;R _W/B the water-to-glue ratio is adopted;

step S4, when the concrete test block is prepared in a laboratory, obtaining the water-cement ratio, the fly ash mixing amount and 28d compressive strength information given in a cement delivery report according to the temperature data transmitted by the temperature sensor, the determined mixing ratio of the single-doped fly ash lightweight aggregate concrete and the used material information, and rapidly predicting the strength of the single-doped fly ash lightweight aggregate concrete in real time;

step S5, when the concrete test block is a construction site sample, if the strength of the concrete structure at any time is to be predicted, the rapid prediction can be carried out according to the formula (2) in the step S3; if the minimum strength value required by form removal is known, obtaining the water-cement ratio, the fly ash mixing amount, the 28d compressive strength given in a cement delivery report and the historical daily average temperature record of the field environment according to the determined mixing ratio of the single-doped fly ash lightweight aggregate concrete and the used material information, and substituting the minimum strength required by form removal of the concrete member into a formula (2) for carrying out inverse calculation to obtain the maturity; and finally, substituting the temperature data and the maturity data obtained by inverse calculation into a formula (1), and obtaining the member form removal time through inverse estimation, wherein the time is the predicted on-site concrete form removal time.

2. The method for rapidly predicting the actual strength of the concrete with the single-doped fly ash lightweight aggregate according to claim 1, wherein the distance between the temperature sensor and the center of the concrete test block is less than or equal to 15mm, and the temperature sensor is in full contact with the concrete test block.

3. The fast predictive mono-blended fly ash light weight of claim 1The method for predicting the actual strength of the aggregate concrete is characterized in that in the step S3, the predicted strength of the concrete test block is 150m³And (5) the strength of the concrete test piece.

4. The method for rapidly predicting the actual strength of a single-blended fly ash lightweight aggregate concrete according to claim 1, wherein the degree of ripeness in the step S3 is calculated according to the age and the curing temperature by the formula (1).

5. The method for rapidly predicting the actual strength of the single-doped fly ash lightweight aggregate concrete according to claim 1, wherein the maturity in the step S3 is directly measured by a concrete maturity tester.

Technical Field

The invention belongs to the technical field of concrete, and particularly relates to a method for quickly predicting actual strength of a single-doped fly ash lightweight aggregate concrete.

Background

Under the background that the demand of cement and concrete is continuously increased, the energy consumption and pollution in the material firing process are reduced, the utilization of solid wastes is increased, and meanwhile, other auxiliary materials are effectively used, so that the performance of the material is improved, the service life is prolonged, the potential performance of the material is developed, and the use of a novel environment-friendly material is a future development trend. The traditional concrete has the defects of great self weight, easy cracking, high manufacturing cost, high energy consumption and the like.

A novel concrete material is developed, namely the lightweight aggregate concrete is a concrete material formed by mixing lightweight aggregate instead of natural sandstone aggregate, has the characteristics of light weight, good heat insulation performance and high impermeability, and is widely applied to the engineering fields of civil high-rise buildings, large-frame bridges and the like.

In addition, dust generated during the production of cement is an important pollutant which causes environmental damage, and many researchers have made efforts to research mineral admixtures, which are substitutes for cement, in order to reduce the environmental burden caused during the production and use of cement. The mineral admixture taking the industrial waste residue or the natural mineral material as the raw material can fill the pores of the cementing material, participate in the hydration of the cementing material, improve the interface structure of the concrete and improve the strength and the durability of the concrete. The fly ash (fly ash) is used as a waste material of a thermoelectric factory, and the mixing of the fly ash (fly ash) can not only ensure the quality of concrete and reduce the cost for manufacturing the concrete, but also improve the workability, durability and later strength of the concrete, thereby becoming the most widely used substitute for countries in the world. However, the large amount of the fly ash can have a remarkable influence on the development of the concrete strength. The concrete strength is the core for guaranteeing the construction quality of the concrete, is an important basis for structural design and construction, and is also an important technical performance index of the concrete. Therefore, an explicit expression calculation model of the strength of the fly ash concrete needs to be established.

The strength of concrete is influenced by various factors, but when the mixing proportion and the construction process are determined, the curing temperature and the age become key factors influencing the strength increase of the concrete. The method for predicting the strength evolution state of the concrete structure by using the maturity method is a feasible real-time in-situ nondestructive testing technology. The maturity method is a technology which comprehensively considers the influence of time and temperature on the development of the concrete strength, and provides a relatively simple evaluation means for the real-time evaluation of the concrete structure strength.

At present, scholars at home and abroad successfully establish different types of concrete compressive strength calculation models based on maturity, however, researches on lightweight aggregate concrete are not many, and the functions of fly ash mixing amount, water-cement ratio and cement strength are not considered in the models.

Therefore, how to establish a relational expression between the maturity and the compressive strength of the fly ash lightweight aggregate concrete and provide a simple and effective means for evaluating the structural strength of the fly ash lightweight aggregate concrete is a technical problem to be solved by those skilled in the art.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information is prior art that is known to a person skilled in the art.

Disclosure of Invention

The invention provides a method for rapidly predicting actual strength of single-doped fly ash lightweight aggregate concrete, which establishes an explicit strength calculation model for rapidly predicting compressive strength of the single-doped fly ash lightweight aggregate concrete by taking fly ash doping amount, water-cement ratio, cement strength and maturity as independent variables, and provides a simple and effective means for evaluating the strength of the single-doped fly ash lightweight aggregate concrete.

In order to solve the technical problems, the invention comprises the following technical scheme:

s1, preparing a plurality of test blocks of the single-doped fly ash lightweight aggregate concrete with different doping amounts, placing the test blocks in groups at different curing temperatures for curing, testing the compressive strength at different ages, and providing a data basis for subsequently establishing a rapid testing formula for predicting the strength of the single-doped fly ash lightweight aggregate concrete;

s2, arranging a temperature sensor in the concrete test block with the single fly ash-doped lightweight aggregate, and uploading temperature data acquired by the temperature sensor to a processor; and (3) calculating the maturity value of the fly ash lightweight aggregate concrete in each age according to the data of each age and the maintenance temperature data by substituting into a formula (1):

M=∑(T-T ₀)·Δt(1)

in the formula:Mmaturity in degrees, unit DEG C·d；TIs a time interval deltatTemperature in concrete, unit ℃;T ₀the reference temperature is the temperature at which the concrete strength does not increase with the age, namely the temperature at which the hydration reaction in the concrete stops, and is usually-10 ℃; deltatIs a time interval, unitd；

Step S3, performing fitting analysis on the test strength data obtained in the step S1 and the maturity information obtained in the step S2, and establishing a strength development curve of the single-doped fly ash lightweight aggregate concrete according to a strength relational expression of the single-doped fly ash lightweight aggregate concrete obtained through the fitting analysis by using the acquired temperature, the known concrete mixing ratio and the material information, which is shown in a formula (2);

f _t =0.2632f _ce ·M·(0.0906R _FA ²+0.0253R _FA +0.9995)·(1/R _W/B -0.304)·(-0.797R _FA ²-0.359R _FA +1.426)/(0.9012M+76.3) (2)

in the formula:f _ce the cement is 28d compressive strength given in a cement factory report, and the unit is MPa;Mthe unit is the maturity of the fly ash lightweight aggregate concrete, and the unit is DEG C.d;R _FA the blending amount of the fly ash is taken as the blending amount of the fly ash;R _W/B the water-to-glue ratio is adopted;

step S4, when the concrete test block is prepared in a laboratory, obtaining the water-cement ratio, the fly ash mixing amount and 28d compressive strength information given in a cement delivery report according to the temperature data transmitted by the temperature sensor, the determined mixing ratio of the single-doped fly ash lightweight aggregate concrete and the used material information, and rapidly predicting the strength of the single-doped fly ash lightweight aggregate concrete in real time;

s5, when the concrete test block is a construction site sample, if the strength of the concrete structure at any moment is to be predicted, the rapid prediction can be carried out according to the relational expression (2) in the S3; if the minimum strength value required by form removal is known, obtaining the water-cement ratio, the fly ash mixing amount, the cement delivery strength and the historical daily average temperature record of the field environment according to the determined mixing ratio of the single-doped fly ash lightweight aggregate concrete and the used material information, and substituting the minimum strength required by form removal of the concrete member into a formula (2) for inverse calculation to obtain the maturity; and finally, substituting the temperature data and the maturity data obtained by inverse calculation into a formula (1), and obtaining the member form removal time through inverse estimation, wherein the time is the predicted on-site concrete form removal time.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the invention provides a method for rapidly predicting actual strength of single-doped fly ash lightweight aggregate concrete, which establishes an explicit rapid prediction and establishment strength calculation model of compressive strength of the single-doped fly ash lightweight aggregate concrete by taking fly ash doping amount, water-cement ratio, cement strength and maturity as independent variables. And the method provides guarantee for strength prediction of the single-doped fly ash lightweight aggregate concrete member under the condition of inconvenient field construction, and simultaneously provides convenience for field construction personnel.

Further, the distance between the temperature sensor and the center of the concrete test block is smaller than or equal to 15mm, and the temperature sensor is fully contacted with the concrete test block.

Further, in the step S3, the predicted concrete block strength is 150m³And (5) the strength of the concrete test piece.

Further, the maturity in the step S3 is calculated according to the age and the curing temperature by the formula (1).

Further, the maturity of the test piece on the construction site in the step S3 may also be measured directly by using a concrete maturity meter.

Drawings

FIG. 1 is a schematic flow chart of a method for rapidly predicting actual strength of a single-doped fly ash lightweight aggregate concrete in one embodiment of the invention;

FIG. 2 is a diagram illustrating the blending ratio of the single-blended fly ash lightweight aggregate concrete in the method for rapidly predicting the actual strength of the single-blended fly ash lightweight aggregate concrete in one embodiment of the present invention;

FIG. 3 is a graph showing the comparison between the actual compressive strength and the predicted compressive strength of fly ash lightweight aggregate concrete of different mix ratios and different ages in the method for rapidly predicting the actual strength of a single-doped fly ash lightweight aggregate concrete in one embodiment of the present invention.

Detailed Description

The method for rapidly predicting the actual strength of the single-doped fly ash lightweight aggregate concrete provided by the invention is further described in detail by combining the attached drawings and specific examples. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention. For convenience of description, the directions of "up" and "down" described below are the same as the directions of "up" and "down" in the drawings, but this is not a limitation of the technical solution of the present invention.