KR101091870B1 - Concrete cure management system - Google Patents

Abstract

The present invention wirelessly receives the temperature of the pour concrete to grasp the current pour concrete temperature data in the field office, not the installation site of the temperature measuring device, using the data to estimate the compressive strength of the concrete based on this demoulding and subsequent It relates to a system that can determine whether the process proceeds.

More specifically, as a system for managing the curing of concrete by transmitting and analyzing the temperature data measured in the concrete curing process through a wireless communication network to a PC,

A temperature sensor (10) embedded in a portion of which a temperature history of concrete is to be measured before placing concrete by using a thermistor element or a thermocouple having a measuring range of -30 to 100 degrees; A signal processor 20 for relaying power to the temperature sensor 10 and removing a noise signal transmitted from the temperature sensor 10; Wired connection to the temperature sensor 10, the CPU board for digitally converting the temperature data passed through the signal processor 20, the power board for supplying power and a wireless modem for wireless transmission of the temperature data provided from the CPU board A data logger 30 configured to include; A reception modem 40 for receiving temperature data information output from the wireless modem; And a PC 50 connected to the reception modem 40 through an RS232C cable or a USB cable to store received temperature data information and to analyze the collected temperature data by using a curing management software. It provides a concrete curing management system, characterized in that configured to include.

Concrete, Curing, Construction Environment, Sensor, Ubiquitous, Zigbee, Wireless, Temperature, Measurement

Description

Concrete cure management system

The present invention relates to a concrete curing management system, in particular, by receiving the temperature of the poured concrete wirelessly to grasp the current poured concrete temperature data from the place where the temperature measuring device is installed, and then to use the data to determine the compressive strength of the concrete The present invention relates to a system capable of estimating formwork demoulding and subsequent processing based on the estimation.

In most cases, the thermometer measurement is carried out in order to cure the quality of the cast-in-place concrete. Especially, in the case of winter-poured concrete, mass concrete, and high-strength concrete, including the low temperature, the importance of thermometer measurement is more important.

The common method used in existing construction sites is to measure the temperature, humidity, salinity, strain, etc. by using the automatic data recording method of the wired line, and then the operator decides the working situation and the future schedule based on the measured data.

However, since the manager must check the measured data related to the curing and take action accordingly, it is difficult to respond quickly and the worker must stay on the site, and the experience of the worker does not allow for scientific and systematic management. There was this.

The present invention has been made to solve the above problems, by installing the temperature sensor 10 in the concrete placement site to detect the temperature history of the concrete in real time, and then transfer it to the site PC using a short-range wireless communication network Only the temperature data can be used to estimate the maturity and compressive strength of the concrete and to determine whether the mold demoulding and the subsequent process will proceed. In addition, since the temperature data is stored in a predetermined server through a wired or wireless communication network, a remote expert can grasp the measured temperature situation in real time, thereby enabling advice and countermeasures regarding abnormality during concrete curing.

The present invention wirelessly receives the temperature of the pour concrete to grasp the current pour concrete temperature data in the field office, not the installation site of the temperature measuring device, using the data to estimate the compressive strength of the concrete based on this demoulding and subsequent It relates to a system that can determine whether the process is in progress.

More specifically, as a system for managing the curing of concrete by transmitting and analyzing the temperature data measured in the concrete curing process through a wireless communication network to a PC,

A temperature sensor (10) embedded in a portion of which a temperature history of concrete is to be measured before placing concrete by using a thermistor element or a thermocouple having a measuring range of -30 to 100 degrees; A signal processor 20 for relaying power to the temperature sensor 10 and removing a noise signal transmitted from the temperature sensor 10; Wired connection to the temperature sensor 10, the CPU board for digitally converting the temperature data passed through the signal processor 20, the power board for supplying power and a wireless modem for wireless transmission of the temperature data provided from the CPU board A data logger 30 configured to include; A reception modem 40 for receiving temperature data information output from the wireless modem; And a PC 50 connected to the reception modem 40 through an RS232C cable or a USB cable to store received temperature data information and to analyze the collected temperature data by using a curing management software. It provides a concrete curing management system, characterized in that configured to include.

When using the present invention,

First, it is possible to calculate the compressive strength automatically with only the temperature history of the poured concrete, so that it is possible to respond quickly in sites with many variables.

Second, the curing management software stored in the PC performs the calculation automatically, so even if you are not an expert, it is possible to find out when the mold dies.

Third, even if an expert is not resident, it is possible to respond, and if necessary, consult a remote expert.

The present invention relates to a concrete curing management system, and in particular, after receiving the temperature of the poured concrete wirelessly to grasp the current pouring concrete temperature data in the field office, not the temperature measuring device installation site, using the data to compress the compressed steel The present invention relates to a system capable of estimating die demoulding and subsequent processes based on the estimation.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings and preferred embodiments.

1 is a view showing the overall configuration of the present invention, as shown in Figure 1 concrete inventors management system of the present invention by transmitting the temperature data measured in the concrete curing process through a wireless communication network to the PC to analyze the curing of concrete As a system to manage, it is comprised including the temperature sensor 10, the signal processing part 20, the data logger 30, the reception modem 40, and the PC 50, and can be provided with the server 60 further. Do.

The temperature sensor 10 generally uses thermocouples (T-types), which have been found to be excellent in measuring range or accuracy, for measuring the temperature of concrete in a laboratory. It is unreasonable to apply in. Therefore, in this system, it is preferable to apply a thermistor (resistance value of 15 kV) that can be measured up to -30 ~ 100 ℃ (error range: ± 1 ℃). Thermistors are not only physically similar to thermocouples, but also much cheaper, and are the most suitable considering the temperature conditions caused by the heat of hydration of concrete and domestic outdoor air temperature conditions.

The signal processor 20 includes a constant voltage unit and a filter unit. The constant voltage unit relays a power supply for operating the temperature sensor 10, and the filter unit removes a noise signal transmitted from the temperature sensor 10. The power supply method may be both a method of directly supplying power using a power cable and a method of supplying power using a storage battery.

The data logger 30 is composed of a CPU board, a power board, and a wireless modem. The CPU board includes an analog digital converter (ADC), a CPU, a flash ROM, and an SDRAM, and digitally converts data passed through the signal processor 20.

In addition, it is preferable that the power board is designed to proceed in a power saving mode, and thus power can be supplied only at a time when data is to be processed to save electricity.

The wireless modem serves to wirelessly transmit the temperature data provided from the CPU board, and the present invention usually has an office in the field and performs wireless transmission at a short distance.

Receiving modem 40 serves to receive the temperature data transmitted through the transmission wireless modem built in the data logger 30, the receiving modem 40 is a PC 50 of the field office and RS232C cable or USB It will be connected via a cable.

Here, the method of wirelessly transmitting the temperature data from the data logger 30 to the PC 50 may use any one of infrared rays, Zigbee, Bluetooth or RF. However, in the present invention, it is preferable to use a local area network because it is sufficient to be able to use it in the field rather than a long distance.

That is, in the present invention, it is preferable to use a Zigbee communication method. Unlike conventional wireless sensor networks, ZigBee communication is attracting attention as a short-range communication that can be operated at low cost, low speed, and low power in homes and offices.It has a small amount of data but can last several months or years with a single battery. This is because of its advantages, network flexibility and scalability.

In addition, the temperature data information received by being connected to the reception modem 40 through an RS232C cable or a USB cable should be stored in the PC 50, and the PC 50 should be provided with curing management software.

In addition, the temperature data transmitted to the PC 50 is stored in a predetermined server through a wired or wireless communication network, it is possible to download and use the PC anywhere. In other words, if the temperature data is stored in the server, even if the expert does not reside in the field, in case of emergency, the expert can download the temperature data from the server and advise on the abnormality during concrete curing. If so, an expert can also run software that calculates the compressive strength by calculating the maturity level.

The curing management software estimates the compressive strength of the concrete by using the temperature data of the transmitted concrete to determine whether there is an abnormality in the concrete curing process and to respond immediately, and further curing, demoulding of the formwork and the progress of the subsequent process. Makes sense.

The curing management software mounted on the PC 50 is a basic data input module for inputting conditions related to concrete curing, and the maturity and compression of concrete for estimating concrete strength using the input basic data and received temperature data. It includes a calculation module for calculating the strength and the output module for outputting the received temperature data, the maturity of the concrete and the compressive strength as a graph over time on the monitor screen.

The basic data input module inputs basic contents related to concrete curing into a computer. The basic data input includes basic physical properties of concrete to be poured and an installation position of a temperature sensor for each channel of the data logger.

2 illustrates an embodiment in which basic data of the present invention is input. As shown in Fig. 2, the 28-day strength of the ready-mixed concrete as the basic physical properties of concrete (f ' _c (28) in Eq. Information necessary for applying the following equations (1), (2), and (3), such as the values of a and b, is input. In addition, the installation position of the temperature sensor for each channel of the data logger is also input.

The maturity of concrete in the calculation module is calculated by the equivalent age by Nurse-Saul function or Arrhenius equation, and the compressive strength of concrete is calculated by the modified equation of ACI strength estimation equation.

Ultimately, the present invention intends to estimate the strength of concrete, and for this purpose, a maturity method is adopted, which enables the strength estimation of concrete from the temperature history measured in real time from the concrete structure. That is, the temperature data measured and transmitted by the wireless sensor network is converted into a temperature change graph by the concrete curing management software, and then, it is constructed to calculate the concrete maturity and estimate the compressive strength from the relationship between temperature and time. .

First, the maturity of concrete is calculated by the equivalent age using the Nurse-Saul function or Arrhenius equation.

The equivalent age (T _es or T _ea ) of concrete shown in Equations (1) and (2) below is a structure whose temperature history is not constant due to the heat of hydration of cement, the influence of outside temperature, curing method, and the cross-sectional size of the member. Standard curing for the degree of curing (or maturity) of the concrete of the structure whose temperature history is not constant due to the method of curing of the concrete and the cross-sectional size of the member. This value is converted to a period. That is, by measuring the temperature history of the structure from the point of concrete placement to a certain point, it is possible to calculate the equivalent age of the concrete up to that point. In this system, the compressive strength was estimated by substituting the calculated equivalent age into the strength-expression equation of the aged cured concrete.

식(1)

Formula (1)

Where T _es : equivalent age (hr or day) by the Nurse-Saul function

T _r : Standard curing temperature (℃), 20 ℃ for calculating equivalent age

        θ: Daily average temperature (or average concrete temperature) (℃)

T ₀ : Standard temperature (℃), generally -10 ℃

식(2)

Equation (2)

Where T _ea : equivalent age (hr or day) by the Arrhenius equation

T _a : 293 ℃, absolute temperature (K) + 20 ℃

E: Activation energy (intrinsic value according to cement type), in case of Class 1 cement, when T _a ≤20 ℃, E = 33.5 + 1.47 (20-T _a ) KJ / mol, T _a ≥20 ℃ E = 33.5 KJ / mol

        R: Gas constant 8.314 J / mol˚K

Next, the compressive strength of the structural concrete uses a modified formula of the ACI strength estimation equation.

That is, as shown in Equation (3) below, the equivalent element (T _es or T _ea ) calculated from the temperature history instead of the actual age (t) was converted into the element (t _e ) on the right side. In addition, the compressive strength of 28 days means the average compressive strength of the 28 days of the age when the concrete applied to the site as a standard curing, but in order to estimate the strength to the safety side in consideration of the temperature difference according to the part of the structure, applying the nominal strength of the ready-mixed concrete It is also possible.

식(3)

Equation (3)

Where f ' _c (t) is the concrete compressive strength at actual age t

        t: arbitrary actual age

t _e : equivalent age at any age t

f ' _c (28): compressive strength at 28 days of age. It is appropriate to apply the nominal strength of the applied concrete in order to estimate the strength to the safety side in all parts of the structure.

       a, b: Coefficients according to the mixing conditions of concrete. 4.0 and 0.85 are applied for general formulations using ordinary Portland cement. However, in the case of concrete applied to ordinary Fordland cement, early strength expression is excellent in the case of the application of roughness marks, so the coefficient value is calculated from the 7-day and 28-day strength of the standard curing law of the concrete applied to the site. Is correct.

On the other hand, Figure 5 is a graph showing the result of comparing the compressive strength of the concrete structure estimated by using the temperature data history transmitted in the present invention and the strength of the core taken from the actual structure. As shown in Figure 5 it can be seen that the estimation results and the actual tendency of the compressive strength of the structure is very similar. In addition, it is possible to increase the accuracy of the strength estimation result by grasping the relationship between the maturity and the compressive strength by the temperature history of the site curing specimens made of concrete applied to each sage.

In addition, the curing management software mounted on the PC 50 can select the start, pause, continuation, and end of work of collecting and analyzing data.

Figure 3 shows an embodiment in which the transmitted temperature data of the present invention as a graph output on the monitor screen and an embodiment in which the calculated maturity and compressive strength of the concrete on the monitor screen as a graph.

As shown in FIG. 3, the transmitted temperature data can be shown in graphs over time on the monitor screen by the curing software. In addition, it is possible to calculate the maturity and compressive strength of concrete over time in the curing management software using the transmitted temperature data, and it is also possible to show a graph over time on the monitor screen.

Figure 4 shows a flow chart of concrete curing quality control in the field according to the present invention.

As shown in Figure 4, after placing the temperature sensor 10 in the site to be measured the temperature history of the concrete before the concrete in the field, by connecting the temperature sensor 10 to the data logger installed on the site to start the thermometer side do. When concrete pouring begins, real-time measurements of the concrete temperature and temperature history over time are made, and the measured temperature values are simultaneously transmitted to a receiver connected to the PC in the field office. The transmitted temperature data is stored on the field computer and displayed on the screen, and stored on the server via the internet network, so that the temperature data can be shared with concrete specialists in remote offices for technical support related to curing of concrete. have.

On-site quality control personnel can check the temperature change of structural concrete in real time and estimate the degree of strength development of concrete at any point in time, and manage curing in response to various on-site conditions including changes in external weather environment conditions. You can do Through this process, it is possible to determine the adequacy of the curing management in real time, and to determine the additional curing period or when to start the subsequent process.

Figure 6 shows the input window and the temperature prediction results of the concrete temperature history prediction software.

In the present invention, the PC 50 may be further provided with temperature history prediction software, and in the case of providing the PC history software, the PC 50 is interlocked with the curing management software.

Concrete temperature history prediction software of the present invention is linked with the above-mentioned curing management software, when selecting the concrete mix in the field, it is possible to simulate the temperature history in advance using the temperature history prediction software. In addition, by inputting the temperature history estimation data into the above-mentioned curing management software, as shown in Fig. 7 to estimate the degree of compressive strength of concrete over time, it is possible to secure the required construction period by member conditions and seasons It is possible to select the concrete mix of the.

As shown in FIG. 6, the specific heat, density, unit cement amount, pouring temperature, pouring time, etc. of the concrete to be poured are input to the concrete condition in the input window of the concrete temperature history prediction software, and the form outside the wall, inside the wall and Enter the material of the slab, and enter the daily average temperature, daily crossover and external wind speed in the outside conditions. In addition, in the condition of rehabilitation, there are various rehabilitation methods necessary for curing, whether there is an upper support roof, whether the opening is closed, whether a wall or slab insulation mat is provided, whether a waterproof sheet is provided, whether the styrofoam + sheet of the slab is provided, and the upper and lower temperature of the indoor side. The temperature inside the upper reserving film is entered. In addition, the size of the member is divided into a wall and a slab, and the hot wire condition is used according to whether the hot wire is used. Hereinafter, a method of predicting the concrete temperature history using the information input in the input window will be described.

The temperature change of the concrete over time can be calculated by the abnormal thermal analysis using the incremental method from the relationship between the total calorific value generated inside the concrete and the total calorific value of the surface portion.

That is, 1) the amount of heat generated by the heat of hydration of cement is calculated from the formula for predicting the thermal insulation temperature rise specified in the concrete standard specification, 2) the amount of heat supplied by the external heat source is calculated, and the amount of heat lost between external conditions 3) Finally, the amount of heat used to raise or lower the temperature of the concrete is obtained by subtracting the amount of heat lost from the total calorific value, and the temperature increase is obtained by calculating the final calorie value with respect to the volume of concrete. 4) The above 1) to 3) process is calculated in order to derive the temperature change value. Hereinafter, the ground calculation formula used in the above process will be described.

-Total calorific value inside the concrete

The total calorific value generated by the concrete inside the cement as the total of the heating value of the heating value (Q _c) and the hot wire heated by the hydration of the cement hydration calorific value (Q _c) are heat-insulated from the formula (4) concrete adiabatic temperature rise equation shown in Hydration calorie per unit time can be calculated by differentiating the temperature with respect to time and multiplying unit weight and specific heat of concrete, and multiplying the value by the cross-sectional thickness of slab to calculate the calorific value of concrete per unit time and unit surface area We can calculate from (5)

식(4)

Formula (4)

Where T: adiabatic temperature rise (℃), t: age (day), multiply by 1/24 for time, K: maximum rise temperature (℃), a: reaction rate coefficient

식(5)

Formula (5)

Where Qc: hydration calorific value (kcal / m ² hr) per unit surface area (1m ² ), ρ _c : density of concrete (2400kg / m ³ ), C _c : specific heat of concrete (0.25kcal / kg ℃), ΔT: Temperature difference of concrete due to hydration heat (℃), Δt: unit elapsed time (hour), d: cross-sectional size of member

In addition, in case of using a buried hot wire, the amount of heat generated by hot wire heating (Q _h ) is determined by the buried spacing of hot wires per unit surface area of concrete member (1m ² ). If the heating wire length per unit surface area is 5m and the heating capacity of the heating wire is 20W / m, it can be calculated by the following equation (6).

                                                             Formula (6)

-Heat loss of surface part

Surface loss of calories per unit per 1m ² hours member Q _t can be obtained from the equation (7) by the difference in heat transfer coefficient of the surface covering material (K _t), member temperature (T _c) and the outside temperature (T _e).

식(7)

Formula (7)

However, it can be said that the heat transfer coefficient according to the type and coating method of the surface coating material is somewhat different in Korea, USA and Japan shown in <Table 1> to <Table 3>. In particular, the type of coating material and the wind speed of the outside air may be the biggest error factor in the prediction of the temperature history of the concrete by the formula. As a result of previous studies on the change of heat transfer coefficient according to the wind speed of outside air, it is 12 ~ 13kcal / m ² · ℃ · hr for the experiment of 大 森川 Dam for wind speed 2 ～ 3m / sec, and 8 ～ 11 kcal / for the experiment of Mt. m ² · ° C. · hr.

-Internal temperature calculation of concrete

The calories directly related to the temperature change of the concrete can be obtained from Q _r (Q _c + Q _h -Q _t ), which is the residual heat obtained from the difference between the total calorific value and the total loss calorie derived above. The concrete temperature at the point in time can be estimated.

식(8)

Formula (8)

Where T _h + Δt: internal temperature of concrete at any time (℃), Δt: unit elapsed time (hour), Q _c : calorific value by hydration of cement, Q _h : calorific value by hot wire, Q _t : total loss calorie

Although the present invention has been described with reference to the accompanying drawings as mentioned above, various modifications and variations are possible without departing from the spirit of the present invention, and may be used in various fields. Therefore, the claims of the present invention include modifications and variations that fall within the true scope of the invention.

1 shows the overall configuration of the present invention.

2 illustrates an embodiment in which basic data of the present invention is input.

Figure 3 shows an embodiment of outputting the graph data on the monitor screen maturity and compressive strength of the concrete calculated from the temperature data and the temperature data transmitted to the present invention.

Figure 4 shows a flow chart of concrete curing quality control in the field according to the present invention.

5 is a graph showing a result of comparing the compressive strength of the concrete structure estimated using the temperature data history transmitted in the present invention and the strength of the core taken from the actual structure.

Figure 6 shows the results of the pre-simulation by the concrete temperature history prediction software for selecting the optimal concrete mix before placing the structural concrete in the present invention.

7 is a graph showing the results of estimating the degree of compressive strength expression with time by the curing management software using temperature data obtained by simulation in advance by the concrete temperature history prediction software.

<Explanation of Symbols for Main Parts of the Drawings>

1: pour concrete

10: temperature sensor

20: signal processing unit

30: data logger

40: receiving modem

50: PC

51: Expert PC

60: server

Claims (9)

As a system to manage the curing of concrete by transmitting the temperature data measured in the concrete curing process through a wireless communication network to a PC and analyzing it, A temperature sensor (10) embedded in a portion of which a temperature history of concrete is to be measured before placing concrete by using a thermistor element or a thermocouple having a measuring range of -30 to 100 degrees; A signal processor 20 for relaying power to the temperature sensor 10 and removing a noise signal transmitted from the temperature sensor 10; Wired connection to the temperature sensor 10, the CPU board for digitally converting the temperature data passed through the signal processor 20, the power board for supplying power and a wireless modem for wireless transmission of the temperature data provided from the CPU board A data logger 30 configured to include; A reception modem 40 for receiving temperature data information output from the wireless modem; And PC 50 for storing the received temperature data information connected to the reception modem 40 and the RS232C cable or a USB cable, and analyzing the collected temperature data using the curing management software; The curing management software includes a basic data input module for inputting a condition related to concrete curing; A calculation module for calculating maturity and compressive strength of concrete for estimating concrete strength using the input basic data and the received temperature data; And an output module for outputting the received temperature data, the maturity of the concrete, and the compressive strength as a graph over time on a monitor screen. The maturity of concrete in the calculation module is calculated by the equivalent age by the Nurse-Saul function or Arrhenius equation, and the compressive strength of concrete is the modified equation of the ACI strength estimation equation.

The variable f ' _c (t) of the modified equation is the concrete compressive strength at the actual age t, t is any actual age, t _e is the equivalent age at any age t, f' _c (28) is the compressive strength of 28 days of age and a and b are the concrete curing management system, characterized in that it is applied according to the mixing conditions of concrete, 4.0 and 0.85 for the general blending with ordinary Portland cement, respectively. delete In claim 1, The input basic data is a concrete curing management system, characterized in that the data including the basic properties of the concrete and the installation position of the temperature sensor for each channel of the data logger. delete In claim 1, the curing management software mounted on the PC 50, Concrete curing management system, characterized in that the selection of the start, pause, continuation, and end of the data collection and analysis work. The method according to any one of claims 1, 3 and 5, The PC 50 includes basic information including basic physical properties of concrete to be poured, physical properties of formwork, outdoor conditions related to concrete curing, maintenance conditions to be added for curing, and heating wire conditions for inputting the size of concrete members and the use of hot wires. It can be linked with the curing management software by additionally equipped with temperature history prediction software for calculating curing temperature change value over time. The concrete curing management, characterized in that by simulating the temperature history of the concrete structure to be poured by input of the basic information in advance, the degree of expression of compressive strength over time by the curing management software can be estimated using the simulation results system. The method according to any one of claims 1, 3 and 5, The power board of the data logger 30 is a concrete curing management system, characterized in that designed to proceed with the power saving mode in which power is supplied only to the time to process the data. The method according to any one of claims 1, 3 and 5, The method of wirelessly transmitting the temperature data from the data logger (30) to the PC (50) is a concrete curing management system, characterized in that any one of infrared, Zigbee, Bluetooth or RF (RF). The method according to any one of claims 1, 3 and 5, The temperature data transmitted to the PC 50 is stored in a predetermined server through a wired / wireless communication network, the concrete curing management system, characterized in that can be downloaded and utilized anywhere in the PC.

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