CN-121992954-A - Large-volume concrete cooling circulation water temperature control construction method in large-temperature difference environment

CN121992954ACN 121992954 ACN121992954 ACN 121992954ACN-121992954-A

Abstract

The invention discloses a large-volume concrete cooling circulation water temperature control construction method in a large-temperature difference environment, and belongs to the technical field of concrete construction. The method comprises the steps of S1, designing a concrete mixing ratio by taking low-temperature cement as a main cementing material, mixing fly ash or slag powder, determining the construction mixing ratio through crack resistance verification, S2, embedding a cooling water pipe and a temperature sensor in a structure based on concrete thermal parameters, connecting external temperature control equipment to form a cooling circulation system, S3, pouring concrete into a mould and layering, monitoring the temperature of the system after covering the cooling water pipe, S4, dynamically adjusting the temperature and flow of the circulating water according to real-time monitoring data, adopting a high-flow low-temperature difference mode or a low-flow high-temperature difference mode aiming at a heating period and a cooling period, carrying out surface heat preservation maintenance, S5, ensuring that the strength of the concrete reaches the standard, enabling the temperature field to be stable, and removing maintenance facilities. The invention realizes the temperature control cracking resistance of the whole process of the mass concrete, solves the cooling adaptation of the large-temperature-difference environment, and improves the construction quality and the cracking resistance.

Inventors

XU PENG
MA JIWEI
CHEN LANG
REN LICAI
MA XIAORUI

Assignees

中国华冶科工集团有限公司

Dates

Publication Date: 20260508
Application Date: 20260306

Claims (9)

1. The large-volume concrete cooling circulation water temperature control construction method in the large-temperature difference environment is characterized by comprising the following steps of: S1, taking low-temperature cement as a main cementing material, mixing fly ash or slag powder for concrete mix proportion design and trial mix, and determining a final construction mix proportion through an anti-cracking verification test; s2, planning and synchronously embedding a cooling water pipe network and a temperature sensor in a mass concrete structure based on thermal parameters of concrete in a construction mixing ratio, and connecting the cooling water pipe network and the temperature sensor to external temperature control equipment to form a cooling circulation system; S3, using the concrete mixed by the construction mixing proportion, controlling the mold entering temperature of the concrete, performing layered pouring, and starting the cooling circulation system and starting temperature monitoring after the concrete covers part of the cooling water pipe; S4, dynamically adjusting the temperature and flow of the circulating water based on real-time temperature monitoring data to control the internal temperature rise and the internal-external temperature difference of the concrete, and simultaneously combining surface heat preservation measures for maintenance; s5, stopping the cooling system and removing the maintenance facility after the strength of the concrete increases to meet the requirement and the temperature field is stable.
2. The method for controlling the temperature of the cooling circulating water of the concrete in a large-volume concrete in a large-temperature-difference environment according to claim 1, wherein in the step S1, the specific step of determining the final construction mix ratio through the crack resistance verification test comprises the following steps: S11, preparing a concrete test piece according to the preliminarily determined mixing ratio; s12, placing the test piece in a temperature circulation box, and simulating a day and night large temperature difference environment in the alpine region of the plateau for maintenance; S13, periodically observing and recording the cracking time, the number of cracks and the width of the surface of the test piece by using a crack observer; s14, comparing the cracking resistance of different proportions by taking the observation result as a key evaluation index, and finally selecting the proportion with the lowest cracking risk as a construction proportion and using the construction proportion for concrete mixing in the subsequent step.
3. The method for controlling the temperature of the large-volume concrete cooling circulation water in the large-temperature-difference environment according to claim 2, wherein the temperature control program of the temperature circulation box is that the highest temperature in daytime is 15 ℃, the lowest temperature at night is-10 ℃, the temperature rise and fall rate is 2-3 ℃ per hour, the single temperature circulation period is 24 hours, the crack observer is an electronic magnifying glass with the magnification of not less than 20 times and the measurement precision of 0.01mm, the observation frequency is 1 day, 3 days, 7 days, 14 days and 28 days after the test piece is molded, and when the crack resistance of different proportions is compared, a weighted comprehensive evaluation system with the initial crack time of 0.3, the total crack number of 0.2, the maximum crack width of 0.3 and the total crack area of 0.2 is adopted, and the proportion that the comprehensive score of the crack resistance is highest and simultaneously meets the designed compression strength and the freezing resistance index is selected.
4. The method for controlling the temperature of the concrete cooling circulation water in a large-volume environment with a large temperature difference according to claim 1, wherein in the step S2, the pipe diameter, arrangement interval and loop length of a cooling water pipe are calculated and determined according to an adiabatic temperature rise prediction curve of a construction proportion and on-site environment conditions, construction parameters comprise an adiabatic temperature rise value, a time for reaching a temperature peak, a heat conductivity coefficient and a specific heat capacity, the cooling water pipe adopts an HDPE pipe with the outer diameter of 32mm and the wall thickness of 2.0mm, the arrangement interval is vertical 0.8m and horizontal 1.2m, the length of a single loop is controlled within 250m, a temperature sensor is a PT1000 platinum resistance thermometer, the temperature sensor is distributed in a three-dimensional grid shape in the concrete, a core high-temperature area is distributed in a 1.0mx1.0mx0.8m interval in an encryption manner, a surface area is connected to a water collector in a parallel manner, and each branch of the water collector is provided with an independent regulating valve and a flowmeter, and the temperature control device with automatic data acquisition and control functions is connected.
5. The method for controlling the temperature of the cooling circulating water of the concrete in the large-volume environment with the large temperature difference according to claim 1, wherein in the step S3, the concrete molding temperature is controlled and layered pouring is performed, which comprises the following specific steps: S31, heating mixing water to 60+/-5 ℃ at a mixing station according to the construction mixing proportion, and preheating aggregate in a heat-insulating shed to above 5 ℃ by introducing hot air; s32, transporting concrete by adopting a thermal insulation tank truck with a double-layer thermal insulation tank body, and carrying out thermal insulation treatment on the tank body during transportation; S33, controlling the time from the outlet to the inlet of the concrete on the casting site to be no more than 90 minutes, adopting a layered continuous casting process, controlling the casting thickness of each layer to be 50cm, controlling the interval time between layers to be no more than the initial setting time of the concrete, controlling the vibration interval to be no more than 50cm, avoiding touching a cooling water pipe and a temperature sensor, immediately starting a cooling circulation system when the thickness of the first layer of cooling water pipe is 50cm when the casting surface of the concrete is covered, setting the initial water supply temperature to be 10-15 ℃ lower than the actual measurement temperature of a concrete core area at the moment, controlling the flow to be 1.2-1.5m 3 /h, and simultaneously automatically acquiring and recording temperature data of each measuring point at a frequency of once every 30 minutes.
6. The method for controlling the temperature of the mass concrete cooling circulation water in the large-temperature-difference environment according to claim 1, wherein in the step S4, the specific step of dynamically adjusting the temperature and the flow of the circulation water to control the internal temperature rise and the internal and external temperature difference of the concrete comprises the following steps: S41, when the rapid rising period that the temperature rising rate of the core temperature in the concrete exceeds 2 ℃ per hour in 4 continuous hours is monitored, starting a cooling mode with large flow and low temperature difference, controlling the difference between the water inlet temperature and the highest temperature in the concrete to be 10-15 ℃, and simultaneously rising the cooling water flow to 1.8-2.2 m 3 per hour so as to accelerate heat export; S42, when the temperature of a core measuring point in the concrete changes within 12 continuous hours to reach a peak value within +/-0.5 ℃ and starts to fall, switching to a cooling mode with small flow and high temperature difference, gradually reducing the difference between the water inlet temperature and the highest temperature in the concrete to be within 5-8 ℃, simultaneously reducing the cooling water flow to 0.8-1.2 m 3 /h, and controlling the cooling rate of the concrete within any 24-hour period to be continuously lower than 2 ℃ per day so as to smooth the temperature shrinkage stress.
7. The method for controlling the temperature of the mass concrete cooling circulation water in the large-temperature-difference environment according to claim 1, wherein in the step S4, the concrete step of simultaneously curing by combining surface heat preservation measures comprises the following steps: s43, after the concrete is finally set, covering a layer of plastic film with the thickness not smaller than 0.12mm for moisturizing, wherein the lap joint width between the films is not smaller than 200mm; s44, tightly covering at least one layer of rock wool heat preservation quilt with the heat conductivity coefficient not more than 0.045W/(mLak) on the plastic film; S45, when the environment is forecast to have rain and snow or the measured ambient temperature is lower than-15 ℃, a layer of waterproof canvas is additionally arranged on the heat preservation quilt, and the joint is sealed by adopting a double-channel pressing strip.
8. The method for controlling the temperature of the mass concrete cooling circulation water in the large-temperature-difference environment according to claim 1, wherein in the step S5, the concrete strength increase is judged to meet the requirement, and the concrete strength increase is judged to be: S51, using construction proportion in the field to keep at least 3 groups of test blocks under the same condition, respectively testing 3 days, 7 days and final strength, and placing the test blocks in a curing box capable of synchronously reproducing the temperature change of the solid structure and the heat preservation environment after removing the test blocks; S52, when the compressive strength test value of the test block reaches more than 75% of the design strength, and simultaneously, the difference between the highest temperature in the concrete and the minimum temperature of the surface layer of all the test points in 24 continuous hours is not more than 20 ℃, and the standard deviation of the temperature data of each test point in the period is less than 2 ℃, judging that the removal condition is met.
9. The method for controlling the temperature of the concrete cooling circulation water in the large-temperature-difference environment according to claim 8, wherein the cooling system is stopped by adopting a staged and step-type operation, the flow of cooling water is firstly reduced to 0.5m 3 /h in three times within 24 hours, meanwhile, the inflow water temperature is raised to the temperature which is not more than 5 ℃ with the environmental temperature, then the circulating water pump is stopped, the monitoring system is kept to work continuously, after the abnormal fluctuation of the temperature data is confirmed after 24 hours, the system is completely stopped, the surface maintenance facilities are orderly removed, and the appearance inspection of the concrete surface is still required for 3 days after the removal.

Description

Large-volume concrete cooling circulation water temperature control construction method in large-temperature difference environment Technical Field The invention relates to the technical field of concrete construction, in particular to a large-volume concrete cooling circulation water temperature control construction method in a large-temperature difference environment. Background The day-night temperature difference in the high-cold area of the plateau often exceeds 25 ℃, and the severe fluctuation is the most direct factor for generating temperature cracks of the mass concrete. The hydration heat release of the concrete can raise the internal temperature, and the night ambient temperature suddenly drops to minus, and the temperature stress generated by the dual temperature gradient easily exceeds the tensile strength of the concrete, so that cracks are caused and the engineering quality is influenced. The existing mass concrete cooling circulation water temperature control technology mainly reduces internal temperature peaks through pre-buried cooling water pipes and unidirectional constant water supply, has good effect under the conventional temperature difference environment, but the static method has defects when being applied to the plateau alpine environment, can press the temperature peaks in daytime, and can accelerate internal temperature reduction and increase internal and external temperature differences by continuously superposing low-temperature water supply and cold environments when the environment is quenched at night, thereby generating huge temperature stress and inducing concrete cracking, and cannot meet the requirement of crack resistance and temperature control. Therefore, the invention provides a water temperature control construction method for the cooling circulation of the concrete in a large-volume in large-temperature-difference environment. Disclosure of Invention The invention aims at solving the problems that in the background technology, a temperature peak can be pressed in daytime, when the environment is quenched at night, continuous low-temperature water is added with the cold environment, the internal temperature reduction is accelerated, the internal and external temperature difference is increased, huge temperature stress is generated, the cracking of concrete is induced, and the requirement of crack resistance and temperature control cannot be met, and provides a large-volume concrete cooling circulation water temperature control construction method in a large-temperature difference environment. The technical scheme of the invention is that the construction method for controlling the temperature of the cooling circulating water of the concrete in a large-volume concrete in a large-temperature-difference environment comprises the following steps: S1, taking low-temperature cement as a main cementing material, mixing fly ash or slag powder for concrete mix proportion design and trial mix, and determining a final construction mix proportion through an anti-cracking verification test; s2, planning and synchronously embedding a cooling water pipe network and a temperature sensor in a mass concrete structure based on thermal parameters of concrete in a construction mixing ratio, and connecting the cooling water pipe network and the temperature sensor to external temperature control equipment to form a cooling circulation system; S3, using the concrete mixed by the construction mixing proportion, controlling the mold entering temperature of the concrete, performing layered pouring, and starting the cooling circulation system and starting temperature monitoring after the concrete covers part of the cooling water pipe; S4, dynamically adjusting the temperature and flow of the circulating water based on real-time temperature monitoring data to control the internal temperature rise and the internal-external temperature difference of the concrete, and simultaneously combining surface heat preservation measures for maintenance; s5, stopping the cooling system and removing the maintenance facility after the strength of the concrete increases to meet the requirement and the temperature field is stable. Optionally, in the step S1, the specific step of determining the final construction mix through the crack resistance verification test includes: S11, preparing a concrete test piece according to the preliminarily determined mixing ratio; s12, placing the test piece in a temperature circulation box, and simulating a day and night large temperature difference environment in the alpine region of the plateau for maintenance; S13, periodically observing and recording the cracking time, the number of cracks and the width of the surface of the test piece by using a crack observer; s14, comparing the cracking resistance of different proportions by taking the observation result as a key evaluation index, and finally selecting the proportion with the lowest cracking risk as a construction propo