Prediction model and method for volume deformation of concrete doped with zeolite and expanding agent
Through the concrete volume deformation prediction model with zeolite and expansion agent, the concrete volume deformation is measured by using an embedded strain gauge, and the prediction model εp(t)=A·εas(t)2+B·εas(t)2+C is established, which solves the volume deformation problem caused by self-shrinkage of concrete and improves the safety and durability of the structure.
Patent Information
- Application Number
- CN202510496205.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-21
- Publication Date
- 2025-08-01
AI Technical Summary
The prior art is difficult to effectively control and predict volume deformation caused by self-shrinkage of concrete, affecting the durability and safety of the structure.
The concrete volume deformation prediction model is used with zeolite and expansion agent, and the concrete volume deformation is measured by an embedded strain gauge, and the prediction model εp(t)=A·εas(t)2+B·εas(t)2+C is established. Combined with the relationship between the expansion agent and the zeolite dosage, the concrete volume deformation changes are predicted.
It effectively reduces the incidence of cracks caused by self-shrinkage of concrete and improves the safety and durability of concrete structures.
Smart Images
Figure CN120412801A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a prediction model and method, and particularly to a prediction model and method for the volume deformation of concrete mixed with zeolite and expansive agent. Background Art
[0002] With the development of the construction field, concrete is increasingly widely used in building structures. Autogenous shrinkage of concrete is one of its inherent physical properties, and this phenomenon is particularly significant during the hardening process of concrete. The internal stress caused by autogenous shrinkage can lead to concrete cracking, affecting the durability and safety performance of the structure. Therefore, it becomes particularly important to understand and control the autogenous shrinkage of concrete. Autogenous shrinkage is not only the autogenous drying shrinkage caused by the decrease in air humidity, but also related to chemical shrinkage and creep caused by pore negative pressure in capillary pores. Especially in the initial stage of hydration of cementitious materials, autogenous shrinkage is extremely likely to occur, which has a significant negative impact on the properties of concrete such as strength, impermeability, and crack resistance.
[0003] To solve the problems brought by autogenous shrinkage of concrete, researchers have developed various methods to reduce or control autogenous shrinkage. Natural zeolite, as an economical and effective mineral admixture, has been widely concerned due to its water absorption characteristics. By adding zeolite, the water in the cement paste can be absorbed, maintaining a low relative humidity level, thereby reducing the autogenous shrinkage of concrete. However, although the application of zeolite is effective, its cost and effect still need to be further optimized. In addition, another commonly used method is to use compensated shrinkage concrete. This method compensates for the concrete shrinkage by generating an expansion effect during the hydration process of the concrete by adding an expansive agent, thereby effectively suppressing the autogenous shrinkage phenomenon.
[0004] In practical applications, the methods for testing the early shrinkage of concrete have also been continuously improved. Traditional methods include the Ang autogenous shrinkage test method, the capacitive micrometer method, and the staged concrete autogenous shrinkage test method, etc. In recent years, the embedded strain gauge method has gradually become the main means for testing the early shrinkage of concrete due to its high precision and stability. This method can directly measure the strain change inside the concrete, thereby more accurately evaluating the degree of autogenous shrinkage. Summary of the Invention
[0005] Object of the Invention: The object of the present invention is to provide a prediction model for the volume deformation of concrete mixed with zeolite and expansive agent to predict the change of concrete volume deformation, reduce the incidence of cracks caused by autogenous shrinkage of concrete, and improve the safety and durability of concrete structures. On the other hand, a method for prediction using the prediction model is provided.
[0006] Technical Solution: For the prediction model described in the present invention, the model for the predicted value of the volume deformation of concrete mixed with zeolite and expansive agent changing with age is:
[0007] ε pε(t) = A·ε(t) + B·ε(t) + C as (t) 2 + B·ε as (t) 2 + C;
[0008]
[0009] Wherein, t represents the age, m z represents the zeolite content, ε p (t) represents the volume deformation value of the concrete with zeolite and expansive agent, A, B, and C represent the influence coefficients related to the content of the expansive agent in the concrete, ε as (t) represents the volume deformation value of the zeolite-containing concrete at the age of t, and α, β represent parameters.
[0010] Preferably, the relationships between A, B, C and the expansive agent content are as follows:
[0011]
[0012] Wherein, m EA represents the expansive agent content.
[0013] Preferably, the relationships between α, β and the corresponding zeolite content are as follows:
[0014]
[0015] Preferably, it is used to obtain the predicted value of the volume deformation of the concrete with zeolite and expansive agent, and characterize the volume deformation of the concrete with expansive agent and zeolite;
[0016] The content of the expansive agent is 0 - 6% of the cement mass;
[0017] The content of the zeolite is 0 - 30% of the sand mass.
[0018] The prediction method of the present invention is carried out according to the following steps:
[0019] S1. Measure the volume deformation of the concrete;
[0020] S2. Pour concrete specimens with different zeolite contents and expansive agent contents;
[0021] S3. Construct a prediction model for the volume deformation of the concrete with zeolite and expansive agent;
[0022] S4. Substitute the values of the zeolite content, the expansive agent content, and the age into the prediction model to obtain the predicted value of the volume deformation of the concrete with zeolite and expansive agent.
[0023] Preferably, in S1, the embedded strain gauge is buried inside the concrete, and the volume deformation of the concrete is measured by the strain box connected to the embedded strain gauge.
[0024] Preferably, S2 includes pouring cement, fine aggregate, coarse aggregate, and water under different working conditions into a mixer in the mixing order until the mixture is evenly mixed, and immediately conducting a slump test on the concrete after mixing is completed.
[0025] Preferably, the slump of the concrete is maintained in the range of 80 - 200 cm.
[0026] Preferably, it further includes pouring the concrete meeting the slump into a PVC pipe, moving it to a vibrating table and vibrating until the mixture is vibration-compacted. After vibration, move the PVC pipe next to the computer equipment, connect the embedded strain gauge to the strain gauge, and at the same time put the temperature probe into the interior of the concrete, and seal and cure the specimen with a plastic film.
[0027] Preferably, S4 analyzes and plots the predicted values through origin software.
[0028] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages: Through the prediction model, it is convenient to know the volume deformation of concrete with any dosage of zeolite and expansive agent at any time. Through real-time testing with the testing device, the incidence rate of cracks caused by autogenous shrinkage of concrete is effectively reduced, and the safety and durability of the concrete structure are improved. Description of the Drawings
[0029] Figure 1 It is a schematic diagram comparing the test values and fitting values of the volume deformation of concrete with different zeolite dosages of the present invention;
[0030] Figure 2 It is a schematic diagram comparing the test values and fitting values of the volume deformation of concrete with 15% zeolite and expansive agent compounded of the present invention;
[0031] Figure 3 It is a schematic diagram comparing the test values and fitting values of the volume deformation of concrete with 30% zeolite and expansive agent compounded of the present invention. Detailed Embodiments
[0032] The technical solution of the present invention will be described in detail below with reference to the drawings.
[0033] The prediction model of the predicted value ε p (t) of the volume deformation of concrete with zeolite and expansive agent changing with age is:
[0034] ε p (t) = A·ε as (t) 2 + B·ε as [[ID= forty-nine ]] 2 + C;
[0035]
[0036] Among them, t represents the age, and m z represents the zeolite content, and ε p (t) represents the volume deformation value of the concrete mixed with zeolite and expansive agent, A, B, and C represent the influence coefficients related to the content of the expansive agent in the concrete, and ε as (t) represents the volume deformation value of the zeolite-mixed concrete at the age of t, and α and β represent parameters.
[0037] The parameters A, B, and C are related to the content of the expansive agent m EA The relationship is as follows:
[0038]
[0039] The relationship between the parameters α, β and the corresponding zeolite content is as follows:
[0040]
[0041] For obtaining the predicted value ε p (t) to characterize the volume deformation of the concrete mixed with expansive agent and zeolite;
[0042] The content of the expansive agent is 0 - 6% of the cement quality;
[0043] The content of the zeolite is 0 - 30% of the sand quality.
[0044] The method for prediction using the volume deformation prediction model of the concrete mixed with zeolite and expansive agent is carried out according to the following steps:
[0045] The concrete shrinkage test refers to ASTM C31M - 18, and the embedded strain gauge method is used to measure the volume deformation of the concrete at 28 days. The strain gauge is embedded inside the concrete, and the strain box connected to the strain gauge measures the volume deformation of the concrete.
[0046] S1. Test preparation.
[0047] First, clean the PVC pipe with a rag, then place the PVC pipe on a wooden board with a length and width of 17 cm. Immediately apply a circle of epoxy resin at the interface between the wooden board and the PVC pipe, and press a concrete cube with a length, width, and height of 10 cm on the top PVC pipe opening for more than half an hour to make the wooden board and the PVC pipe stably bonded. In addition, connect the strain gauge to the strain box to test whether the embedded strain gauge for the test is in good condition. Combine the above PVC pipe, strain gauge, and strain box to form the entire concrete deformation test system.
[0048] S2. Specimen pouring.
[0049] Pour the cement, fine aggregate, coarse aggregate, and water under each working condition into the mixer in the mixing order until the mixture is evenly mixed. Immediately conduct a slump test on the concrete after mixing to keep its slump within the range of 80 - 200 cm, so as to endow the concrete with good fluidity and spreadability.
[0050] S3. Specimen molding.
[0051] Pour the concrete meeting the slump requirement into a cylindrical PVC pipe with a diameter of 110 mm, a height of 420 mm, and a wall thickness of 3.2 mm. When it is poured to half of the height of the mold, place the strain gauge upright on the concrete, and then continue to add materials evenly on both sides. When the height of the concrete is close to the top, move it to the vibrating table and vibrate until the mixture is vibration-compacted. During this period, it is necessary to ensure that the position of the strain gauge does not change significantly. After vibration, move the PVC pipe next to the computer equipment, connect the strain gauge to the strain gauge instrument, and at the same time put the temperature probe into the concrete until it reaches the middle of the concrete. Then gently tap the PVC pipe to make the holes disappear. After all equipment is connected, seal the specimen with 3 layers of thick plastic film and cure it in an environment with a temperature of (20 ± 2) °C and a relative humidity of (60 ± 5)%.
[0052] S4. Specimen measurement.
[0053] Connect the strain gauge embedded in the concrete to the strain box to measure the shrinkage deformation of the concrete.
[0054] S5. Test arrangement.
[0055] After the 28-day age is reached, extract the deformation data and turn off equipment and instruments such as the strain box for the next group of tests.
[0056] Specifically as follows:
[0057] (1) The test raw materials are PII 52.5 Portland cement, zeolite, and expansive agent (a mixture of calcium oxide and calcium sulfoaluminate expansive agent prepared according to a mass ratio of 7:3).
[0058] (2) After the specimen is mixed, it is filled into a cylindrical glass tube with a diameter of 27 mm and a length of 200 mm. The pouring height of the specimen is about 2 - 3 cm. The specimen composition under each working condition is shown in Table 1 below:
[0059] Table 1 Mix proportion of concrete volume deformation test under different working conditions
[0060]
[0061]
[0062] Note: All specimens are concrete. 0.35Z15 and 0.35Z30 represent specimens with a water-cement ratio of 0.35 and zeolite dosages of 15% and 30% respectively. 0.35Z15EA3 and 0.35Z15EA6 represent specimens with a water-cement ratio of 0.35, a zeolite dosage of 15%, and expansive agent dosages of 3% and 6% respectively.
[0063] (3) Use origin software to analyze and plot the data and analyze the test data.
[0064] (4) The test data of zeolite-containing concrete with a water-cement ratio of 0.35 at different ages and the predicted curve of the model of the present invention are as Figure 1 shown. The test data of concrete containing zeolite and expansive agent at different ages and the predicted curve of the model of the present invention are as Figure 2 and Figure 3 shown. It can be seen from Figure 1 that as the zeolite dosage increases, the curve of the concrete volume deformation ε as (t) value gradually decreases. It can be seen from Figure 2 and Figure 3 that on the basis of adding zeolite, when an expansive agent is further added, the concrete volume deformation value ε p (t) is further reduced.
[0065] (5) Establish a prediction model for the change and development of the volume deformation of concrete containing zeolite and expansive agent. According to the test results, the model of the volume deformation value ε p (t) of concrete containing zeolite and expansive agent changing with time is as follows.
[0066] ε p (t) = A·ε as (t) 2 + B·ε as (t) 2 + C;
[0067]
[0068] Among them, t represents the age, m z represents the zeolite dosage, ε p (t) represents the volume deformation value of concrete containing zeolite and expansive agent, A, B, and C represent influence coefficients related to the expansive agent dosage in the concrete, ε as (t) represents the volume deformation value of zeolite-containing concrete at the age of t, and α and β represent parameters.
[0069] The relationship between the parameters A, B, and c and the expansive agent dosage m EA is as follows, and the values and correlations are shown in Table 2:
[0070]
[0071] Table 2 Values and Relevance Degrees of Parameters A, B, and C
[0072]
[0073] The relationships between parameters α, β and the corresponding zeolite dosages are as follows, and the values and relevance degrees are shown in Table 3:
[0074]
[0075]
[0076] Table 3 Values and Relevance Degrees of Parameters α, β
[0077]
[0078] (6) It can be seen from Tables 2 and 3 that the correlation degrees between the experimental values and the fitting values of the volume deformation ε p (t) of the concrete mixed with zeolite and expansive agent changing with time are all above 98%, with a relatively high correlation degree, indicating that the model can well characterize the trend of the volume deformation value ε p (t) of the concrete mixed with zeolite and expansive agent changing with time t, and the expression of the model parameter relationship is simple.
Claims
1. A prediction model for the volume deformation of concrete mixed with zeolite and expansive agent, characterized in that, The model for the variation of the predicted value of the volume deformation of zeolite- and expansive agent-containing concrete with age is as follows: ε p (t) = A·ε as (t) 2 + B·ε as (t) 2 + C; Among them, t represents the age, and m z represents the zeolite content, and ε p (t) represents the volume deformation value of the concrete mixed with zeolite and expansive agent. A, B, and C represent the influence coefficients related to the content of the expansive agent in the concrete, and ε as (t) represents the volume deformation value of the zeolite-containing concrete at the age of t. α and β represent parameters.
2. The prediction model according to claim 1, wherein The relationships between A, B, and C and the dosage of the expansive agent are as follows: Among them, m EA represents the dosage of expansive agent.
3. The prediction model according to claim 1, characterized in that The relationships between α, β and the corresponding zeolite dosages are as follows:
4. The prediction model according to claim 1, characterized in that It is used to obtain the predicted value of the volume deformation of zeolite- and expansive agent-containing concrete, and characterize the volume deformation of concrete containing expansive agent and zeolite; The dosage of the expansive agent is 0 - 6% of the mass of cement; The dosage of the zeolite is 0 - 30% of the mass of sand.
5. A method for prediction using claim 1, characterized in that It is carried out according to the following steps: S1. Measure the volume deformation of the concrete; S2. Pour concrete specimens with different zeolite dosages and expansive agent dosages; S3. Construct a prediction model for the volume deformation of zeolite- and expansive agent-containing concrete; S4. Substitute the values of the zeolite dosage, the expansive agent dosage, and the age into the prediction model to obtain the predicted value of the volume deformation of zeolite- and expansive agent-containing concrete.
6. The method according to claim 5, wherein In S1, the volume deformation of the concrete is measured by burying an embedded strain gauge inside the concrete and using a strain box connected to the embedded strain gauge.
7. The method according to claim 5, characterized in that S2 includes pouring cement, fine aggregate, coarse aggregate, and water under different working conditions into a mixer in the mixing order until the mixture is evenly mixed, and immediately conducting a concrete slump test after mixing is completed.
8. The method according to claim 7, wherein Keep the concrete slump within the range of 80 - 200 cm.
9. The method according to claim 8, wherein It also includes pouring the concrete meeting the slump into a PVC pipe, moving it to a vibrating table and vibrating until the mixture is vibration-compacted. After vibration, move the PVC pipe next to the computer equipment, connect the embedded strain gauge to a strain gauge, and at the same time put a temperature probe into the concrete, and seal and cure the specimen with a plastic film.
10. The method according to claim 5, characterized in that In S4, the predicted value is analyzed and plotted by origin software.