KR101290947B1 - Method for predicting compaction time of asphalt and recording medium storing program of the same - Google Patents

Abstract

PURPOSE: An asphalt compaction time predicting method and a recording medium recording a program implementing the same are provided to predict a temperature change profile of asphalt, thereby efficiently performing asphalt compaction. CONSTITUTION: State information, environment information and a heat conduction constant of an asphalt mixture are inputted (S1130). A temperature profile is made using the state information, the environment information and the heat conduction constant of the asphalt mixture (S1140). The temperature profile of the asphalt mixture is expressed as a temperature value of the asphalt mixture according to time. Time taken until a predetermined compaction stop temperature is calculated by applying the predetermined compaction stop temperature in the temperature profile of the asphalt mixture (S1150). [Reference numerals] (S1110) Input the state information of an asphalt mixture; (S1120) Iput environment information; (S1130) Input the heat conduction constant of the asphalt mixture; (S1140) Calculate the temperature profile of the asphalt mixture; (S1150) Calculate time taken until a predetermined compaction stop temperature

Description

Method for predicting compaction time of asphalt and recording medium storing program of the same}

The present invention relates to a method for estimating asphalt compaction time and a recording medium recording a program for implementing the method. More specifically, the state information of the asphalt mixture, environmental information and the thermal conductivity constant of the asphalt mixture are input, and the state information of the asphalt mixture. To calculate the temperature profile of the asphalt mixture using environmental information and thermal conductivity constants, and to estimate the time to the compaction stopping temperature using the calculated temperature profile of the asphalt mixture. A recording medium recorded.

In paving roads, asphalt, a mixture of asphalt and aggregates is generally used. Asphalt pavement has high resistance to slipping, low noise and good adaptability to the ground. In addition, there is an advantage that the riding comfort during driving can be suppressed and the damage of the vehicle can be suppressed.

Asphalt mixture is hardened in the public process after laying, in which the aging of asphalt continues continuously until 2 ~ 3 years after the asphalt mixture of pavement reaches limit density due to consolidation due to traffic load. This is mainly due to the oxidation reaction occurring between oxygen and asphalt in the atmosphere, but this phenomenon is accelerated when the penetration of air, water, and light becomes easy due to the large amount of voids in the asphalt pavement or the occurrence of cracks. Here, the factor which most influences the asphalt aging phenomenon of the pavement in common is the porosity of the mixture. That is, the porosity is important for laying asphalt mixture. The compaction process is an important construction process that determines the long-term compatibility of the asphalt pavement. The asphalt mixture is compacted to a suitable density and porosity by the compaction process.

The compaction process should be appropriate for the characteristics of the asphalt mixture heated by the compaction equipment or for environmental factors. By varying the compaction time and compaction method in consideration of the characteristics of the asphalt mixture or environmental factors, it is possible to resist breakage due to the load of the vehicle and the driving environment, and to prevent plastic deformation, thereby exhibiting the best common characteristics.

One of the important factors in the compaction process is the compaction temperature of the asphalt mixture. In order to efficiently carry out the compaction process, the temperature during compaction of the asphalt is important. When the asphalt is compacted at 93.3 ° C, the porosity is 2.4 times higher than the compaction at 135 ° C, and when the asphalt is compacted at 79.4 ° C, the porosity is four times higher than when compacted at 135 ° C. It means that the efficiency is lowered. Therefore, in order to perform the compaction process more efficiently, it is necessary to follow the minimum required temperature in the compaction process. However, it is not easy to continuously measure the temperature change of the asphalt mixture over time and predict compaction time from the site.

Therefore, it is possible to easily predict the temperature change of the asphalt mixture at the site compaction, and thus a method for estimating the appropriate compaction time is needed by estimating the time to the compaction stop temperature. In addition, in the prediction of the temperature profile of the asphalt mixture, there is a need for a method of calculating the compaction time by reflecting the temperature in consideration of weather conditions including atmospheric temperature, humidity, and the like.

An object of the present invention is to provide an asphalt compaction time prediction method that can predict compaction time by predicting the temperature of the asphalt mixture.

In addition, in estimating the temperature of the asphalt mixture, it is to provide an asphalt compaction time prediction method that can predict the compaction time by accurately predicting the temperature of the asphalt mixture by reflecting environmental factors and site conditions.

Another object of the present invention is to provide an asphalt compaction time prediction method with improved reliability by correcting the predicted temperature profile using temperature profile values of the asphalt mixture measured in the compaction process.

In order to achieve the above object, the asphalt compaction time prediction method according to an embodiment of the present invention, the step of receiving the state information of the asphalt mixture, the step of receiving environmental information, the step of receiving the thermal conductivity constant of the asphalt mixture, asphalt mixture Computing the temperature profile of the asphalt mixture using the state information of the environment, environmental information, the thermal conductivity constant of the asphalt mixture, and using the temperature profile of the asphalt mixture to calculate the time taken to stop the compaction temperature.

In the asphalt compaction time prediction method according to another embodiment of the present invention, the state information of the asphalt mixture may be the type of the asphalt mixture, the mixing ratio of the asphalt mixture, the thickness of the asphalt laid, and the temperature of the asphalt laid.

In the asphalt compaction time prediction method according to another embodiment of the present invention, the environmental information may be a temperature, an air temperature, a wind speed, and a cloud amount of the asphalt contact surface.

In the asphalt compaction time prediction method according to another embodiment of the present invention, the step of measuring the temperature profile of the asphalt mixture to be installed and the error of the two profiles by comparing the temperature profile of the calculated asphalt mixture and the measured asphalt mixture The method may further include calibrating the temperature profile of the asphalt mixture calculated to be the minimum value. The temperature profile of the calibrated asphalt mixture can be used to recalculate the time to compaction stop temperature.

In the asphalt compaction time prediction method according to another embodiment of the present invention the temperature profile of the asphalt mixture is

에 의해 산출될 수 있다. 산출된 온도 프로파일은 표면 온도 프로파일이다. 여기서, T_{1 (t)}는 시간 t에서의 아스팔트 혼합물의 표면 온도, T_{1 (t+Δt)}는 시간 (t+Δt)에서의 아스팔트 혼합물의 표면 온도, T_2(t)는 시간 2에서의 증분 온도, α는 아스팔트 혼합물의 열확산율, △t는 시간 변화량, △z는 아스팔트 혼합물의 두께 변화량, N_bi는 비오 넘버, Ta는 대기 온도, H_s는 태양 에너지의 영향도, a는 아스팔트 혼합물의 총흡수율, ε는 아스팔트 혼합물의 총 방출량, σ는 스테판-볼츠만 상수이다.

Can be calculated by The calculated temperature profile is a surface temperature profile. Where T _{1 (t)} is the surface temperature of the asphalt mixture at time t, T _{1 (t + Δt)} is the surface temperature of the asphalt mixture at time t + Δt, and T _{2 (t)} is at time 2 Incremental temperature, α is the thermal diffusivity of the asphalt mixture, Δt is the time variation, Δz is the thickness variation of the asphalt mixture, N _bi is the bionumber, Ta is the atmospheric temperature, H _s is the influence of solar energy, a is the asphalt mixture Is the total absorption of ε, the total emissions of the asphalt mixture, and σ is the Stefan-Boltzmann constant.

에 의해 산출될 수 있다. 산출된 온도 프로파일은 내부 온도 프로파일이다. 여기서, T_{t ,z}는 아스팔트 깊이에 따른 시간 t에서의 아스팔트 혼합물의 온도, T_(t+Δt),z는 아스팔트 깊이에 따른 시간 (t+Δt)에서의 아스팔트 혼합물의 온도이다.In the asphalt compaction time prediction method according to another embodiment of the present invention, the internal temperature profile of the asphalt mixture is

Can be calculated by The calculated temperature profile is an internal temperature profile. Where T _{t , z} is the temperature of the asphalt mixture at time t according to the asphalt depth, T _{(t + Δt), z} is the temperature of the asphalt mixture at time (t + Δt) along the asphalt depth.

A program for implementing the asphalt compaction time prediction method according to an embodiment of the present invention can be recorded on a recording medium.

Asphalt compacting time prediction method of the present invention can efficiently asphalt compaction by predicting the temperature change profile of the asphalt, the first compaction, the second compaction, the finishing compaction can be made at the appropriate temperature to improve the commonness of the paved road Can be.

The asphalt compaction time prediction method of the present invention can predict the temperature of the asphalt mixture more accurately by reflecting environmental factors in predicting the temperature of the asphalt mixture.

The asphalt compaction time prediction method of the present invention can predict a more accurate temperature profile by correcting the temperature profile of the asphalt mixture to a value that minimizes the error with the measured temperature profile of the asphalt mixture.

1 is a flowchart illustrating a method for predicting asphalt compaction time according to an embodiment of the present invention.
2 is a graph showing that the thermal conductivity varies according to the characteristics of the asphalt mixture.
3 is a flowchart illustrating a method for predicting asphalt compaction time according to another embodiment of the present invention.
4 is a view showing the predicted temperature profile and the measured temperature profile in the asphalt compaction time prediction method according to another embodiment of the present invention.
5 is a block diagram illustrating an apparatus for predicting asphalt compaction time according to an exemplary embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that, in the drawings, the same components are denoted by the same reference symbols as possible. Further, the detailed description of known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, some of the components in the drawings are exaggerated, omitted, or schematically illustrated.

1 is a flowchart illustrating a method for predicting asphalt compaction time according to an exemplary embodiment of the present invention, and FIG. 2 is a graph illustrating a change in thermal conductivity according to characteristics of an asphalt mixture.

Compaction process is a process of compacting by applying a constant pressure to the asphalt laid during road laying, and has a great impact on the performance of the road, that is, the commonness of the pavement. Roads with adequate compaction cost less to repair and can maintain long-term performance. The compaction process increases the density of the asphalt mixture laid on the road and compacts it to a uniform density. The compaction process is divided into the first compaction, the second compaction, and the finishing compaction step. A roller, tire roller, vibratory roller, etc. are used to compact the asphalt mixture. Usually, the first compaction uses a roller (mercadom, tandem roller), the second compaction, a tire, a roller or a vibrating roller, and the finishing compaction is a tire, a roller.

The first compaction is carried out at a temperature as high as possible to avoid displacement or hair cracking of the mixture with a Mercadum roller. The compaction temperature is 140 to 160 ° C. and the number of compactions is about 2 to 4 times. After the first compaction, the tire roller is continuously subjected to sufficient 8-10 times with the first compaction, and the compaction temperature is generally 110 to 130 ° C. Finishing compaction is done using tires and tandem rollers to correct unevenness or roller marks. The number of times is 2 ~ 4 times and the compaction temperature is 90 ~ 100 ℃. If the compaction temperature is too high, the asphalt mixture may not be in a stable state, and the density may be uneven or the porosity may vary depending on the location of the asphalt. Conversely, if you chop at too low a temperature, it will not be compacted to the desired density. Therefore, the compaction time is estimated by predicting the temperature of the asphalt mixture in the first compaction, the second compaction, and the final compaction process.

As asphalt has viscoelastic behavior, temperature is an important parameter not only for the mechanical properties of the asphalt mixture, but also for the compaction process for the concrete pavement of the asphalt mixture. When paving an asphalt mixture, the cooling rate of the asphalt mixture depends on the initial temperature and environmental factors (eg atmospheric temperature, weather conditions) and also affects the compaction time to achieve optimum density. The faster the cooling rate, the faster the compaction process will be, resulting in time constraints. In order to cope with this, it is necessary to predict the temperature profile of the asphalt mixture to be installed.

In order to implement the asphalt compaction time prediction method according to an embodiment of the present invention, the temperature profile of the asphalt mixture is calculated. The thermodynamic properties of the asphalt mixture (PFC) are used to calculate the temperature profile of the asphalt mixture. In an embodiment of the present invention, the temperature of the asphalt over time is determined using the thermodynamic properties of the asphalt mixture. In general, the thermal conductivity values of drainage asphalt mixtures are small compared to dense asphalt mixtures. This is because the density of the drainable asphalt and the dense asphalt is different, the density of the drainable asphalt is less than the density of the dense asphalt.

The compaction temperature profile is predicted through a simulation program based on one dimensional heat conduction equation, finite difference method, and environmental conditions.

As shown in FIG. 1, in order to perform the asphalt compaction time prediction method according to the embodiment of the present invention, state information of the asphalt mixture is received (S1110). The asphalt state information includes the type of asphalt mixture, the mixing ratio of the asphalt mixture, the thickness of the asphalt laid, the temperature of the asphalt laid, and the like. The thermal properties of the asphalt mixture, such as thermal conductivity, thermal diffusivity, and heat capacity, depend on the type of aggregate or mix ratio that makes up the asphalt mixture. For example, when the mixing ratio of asphalt is low, the porosity increases and the thermal conductivity decreases. That is, the physical properties of the asphalt mixture affects the thermal conductivity, and as shown in FIG. 2, the thermal conductivity varies according to the mixture characteristics such as asphalt amount, voids, aggregate porosity (VMA), and saturation (VFA). In FIG. 2 (a), the thermal conductivity increases as the amount of asphalt increases, and in FIG. 2 (b), the thermal conductivity decreases as the voids increase. This trend shows a similar pattern in aggregate gap (VMA) and saturation (VFA). The temperature profile of the asphalt mixture also depends on the depth of the asphalt being laid and the initial temperature of the asphalt mixture.

Next, the environment information is received (S1120). The environmental information includes the status information of the site where the asphalt is laid, such as the properties of the asphalt contact surface and the temperature of the asphalt contact surface, and weather information such as air temperature, wind speed, humidity, solar radiation level, and cloud amount. The temperature, air temperature, wind speed, humidity, solar radiation level, and cloudiness of the asphalt contact surfaces influence the cooling of the asphalt mixture. This environmental information can be used to calculate the convection and radiative effects in cooling the asphalt mixture. The characteristics and thickness of the asphalt mixture, wind speed and humidity, solar radiation levels and cloud cover are measured and entered on site. Information such as the input wind speed and cloud amount may be parameterized and used according to a preset rule. In this case, a plurality of environment parameters are generated using respective environment information input. In another embodiment, information such as wind speed, humidity, cloud cover, etc. may be received and input from the Meteorological Agency server.

The thermal conductivity constant of the asphalt mixture is received (S1130). Thermal conductivity constants of asphalt mixtures include conductivity and diffusion rate. Conductivity and diffusion are important parameters in predicting the temperature of asphalt mixtures. The conductivity and diffusivity of the asphalt mixture affect the behavior of the temperature profile. In this example, the conductivity and the diffusivity are measured using the probe method. The top needle is usually a needle or surface type probe. In this example, a 5 cm diameter surface type probe was used. Surface type probes have the advantage of being more accurate because they measure a larger area compared to needle type probes. When the surface-type probe comes in contact with the asphalt specimen, a constant current flows, and the conductivity and diffusion are calculated based on the temperature difference between the initial temperature and the heat and then the last temperature.

In another embodiment, the average density and thermal conductivity may be obtained by conductivity test of the asphalt mixture. The following is an example of conducting conductivity test using drainage asphalt. Crushed granite and PG64-22 with different modifiers at different sites were mixed to create a drainage package. The conductivity test of the drainage package was compacted in the laboratory using the plant mixture. The Marshall compactor was applied 50 times to make specimens 100 mm in diameter and 50 mm in diameter.

Aggregate distribution and mixture volume characteristics are as follows.

Conductivity was measured using two specimens, respectively. Conductivity test was conducted based on ASTM D5334-92. Instead of the needle-type needle probe sensor used as a standard, a circular sensor of a surface probe of Quickline was used. Surface type probes are more accurate than needle type probes because they have a larger measuring surface. Conductivity measurement ranges from 0.3 to 2.0 W / mK with accuracy less than 10%. In addition, the density of the asphalt mixture is measured at regular time intervals using a density density gauge on the road through which each compaction equipment passes.

Table 2 shows the measured density and thermal conductivity (k).

Three repeated tests measured the thermal conductivity values. As shown in Table 2, it can be seen that the thermal conductivity of the base layer is higher than that of the drainable asphalt mixture. This means that the thermal conductivity of the base layer is expected to increase, which is due to the larger particle to particle contact due to the smaller porosity of the dense asphalt mixture.

Next, the temperature profile of the asphalt mixture is calculated using the inputted state information, environmental information, and thermal conductivity constants of the asphalt mixture (S1140).

The theory of heat transfer is explained to calculate the temperature profile of the asphalt mixture. Heat transfer through a solid is explained by Fourier's law that the theory of transfer or heat flow in a given direction is proportional to the change in temperature in that direction by a proportional constant called thermal conductivity.

One-dimensional normal heat conduction is described by following Formula (1).

------------------------------ (식 1)

------------------------------ (Equation 1)

Here, temperature T is a dimensionless temperature and is defined as follows.

------------------------------- (식 2)

------------------------------- (Equation 2)

(T _u = unknown temperature at a specific location and time in the asphalt mixture,

T _a = ambient temperature,

T _o = initial temperature of asphalt mixture when asphalt mixture is laid)

Specific heat and thermal diffusivity are needed to explain the heat transfer flow. Specific heat refers to the amount of heat required to raise the temperature of the material by 1 degree. Thermal diffusivity refers to the rate of heat propagation.

The thermal diffusivity is defined as

---------------------------------- (식 3)

---------------------------------- (Equation 3)

(α = thermal diffusivity, m ² / s,

ρ = density, kg / m ³ ,

C = specific heat, J / kgK)

On the other hand, the temperature change rate is as follows.

---------------------------------- (식 4)

---------------------------------- (Equation 4)

Solving equations (1) and (4) on the assumption that the thermal diffusivity is constant, the partial differential equation of the heat flow transfer can be obtained as follows.

---------------------------- (식 5)

---------------------------- (Equation 5)

Solving equations (3) and (5) is as follows.

-------------------------------- (식 6)

-------------------------------- (Equation 6)

(t = hours, seconds)

In this embodiment, the thermal conductivity and thermal diffusivity are measured and input by the probe method. The temperature profile of the initial asphalt mixture is assumed to be constant and the same as after laying. In order to calculate the density change of the drainage asphalt mixture using the degree of compaction and the degree of cooling of the asphalt mixture layer, the density input is included as a function of the compaction time t. The density input changes with time t, but it is assumed that the density is uniform for the depth of the asphalt mixture layer.

The boundary conditions at the surface of the laid asphalt mixture are explained by the transfer of thermal energy with ambient temperature. The energy balance over the finite element of the asphalt mixture is derived as follows.

(식 7)

(Equation 7)

(T _{1 (t)} = surface temperature of the asphalt mixture at time t,

T _{1 (t + Δt)} = surface temperature of the asphalt mixture at time (t + Δt),

T _{2 (t)} = incremental temperature at time 2,

α = thermal diffusivity of the asphalt mixture,

Δt = time variation,

Δz = change in thickness of the asphalt mixture,

N _bi = bio number,

T _a = ambient temperature,

H _s = influence of solar energy,

a = total absorption of asphalt mixture,

ε = total discharge of asphalt mixture,

σ = Stefan-Boltzmann constant)

As the compacting process proceeds, the thermal diffusivity changes with the density due to the change in compaction degree. The changing thermal diffusivity (α) is replaced by the specific heat (C) and thermal conductivity (k) as follows.

------- (식 8)

------- (Equation 8)

Using Equation 6, the temperature T with depth z and time (t + dt) in the asphalt mixture pavement layer is determined as follows.

------------------------------- (식 9)

------------------------------- (Equation 9)

(T _{t, z} = temperature of the asphalt mixture at time t along the asphalt depth,

T _{(t + Δt), z} = temperature of the asphalt mixture at time (t + Δt) along the asphalt depth)

In order to calculate the temperature profile of the asphalt mixture according to the embodiment of the present invention, the paving temperature, the atmospheric temperature, and the existing layer surface temperature before laying were measured before pavement compaction, which is as follows.

These initial temperatures are used to define the initial and boundary conditions of the heat and thermal energy flow in the pavement layer. In this example, the temperature profile was predicted using the thermal conductivity (k) of [Table 2] and the environmental information of [Table 3].

The equations (7) to (9) described above are implemented by a finite difference program that takes into account the compactness of the measured packing density and the nonlinear deformation depending on the degree of cooling time. In each asphalt mixture test section, a numerical solution was created based on the change in average thermal conductivity values shown in Table 2 for the prediction of the cooling time. In the numerical solution process, the thickness of the 50 mm asphalt mixture was chosen to fit 10 elements in the finite-difference grid and the time step t = 1 sec was chosen to confirm that the numerical stability and accuracy were satisfied. As can be seen in FIG. 3, for most of the test section, the prediction using the installed density as a function of the cooling time is shown to be close to the prediction of the cooling time compared to the measured value. It also shows that the effect of changes in measured thermal conductivity values on cooling time less than 10 minutes has a small effect on the predicted cooling time.

으로부터도 알 수 있다. In general, the smaller the thermal conductivity value at a given density, the longer the cooling time is expected. On the other hand, the smaller the density value at a given thermal conductivity, the shorter the cooling time is predicted. This relationship is such that the change in temperature is directly proportional to thermal conductivity (k) and inversely proportional to density (ρ).

It can also be seen from.

On the other hand, the compaction process is divided into the first compaction, the second compaction, the finishing compaction process, the asphalt mixture to be installed shows a rapid temperature change on the surface, especially when the weather conditions are bad. The primary compaction temperature is therefore based on the surface temperature of the asphalt mixture. The second compaction and finishing compaction temperature, on the other hand, is based on the internal temperature of the asphalt mixture. In the present embodiment, the first compaction temperature is expressed by

(T _{1 (t)} = surface temperature of the asphalt mixture at time t,

T _{1 (t + Δt)} = surface temperature of the asphalt mixture at time (t + Δt),

T _{2 (t)} = incremental temperature at time 2,

α = thermal diffusivity of the asphalt mixture,

Δt = time variation,

Δz = change in thickness of the asphalt mixture,

N _bi = bio number,

T _a = ambient temperature,

H _s = influence of solar energy,

a = total absorption of asphalt mixture,

ε = total discharge of asphalt mixture,

sigma = Stefan-Boltzmann constant). The surface temperature profile of the asphalt mixture laid by the above formula is calculated. The surface temperature of the asphalt mixture is the basis of the first compaction temperature that should be carried out quickly at high temperatures, and the surface temperature profile is used to estimate the primary compaction temperature.

(T_{t ,z} = 아스팔트 깊이에 따른 시간 t에서의 아스팔트 혼합물의 온도, T_(t+Δt),z = 아스팔트 깊이에 따른 시간 (t+Δt)에서의 아스팔트 혼합물의 온도)로부터 산출되는 내부 온도 프로파일을 이용하여 구할 수 있다. 포설되는 아스팔트의 내부 온도는 포설층의 두께 및 다짐의 정도에 따라 변화한다. 아스팔트 혼합물의 내부 온도는 다짐을 충분히 실시하여야 하는 2차 다짐 및 마무리 다짐 온도의 기준으로 하며, 내부 온도 프로파일은 2차 다짐 및 마무리 다짐 온도를 산정하는데 이용된다.Second compaction and finishing compaction temperature

Internal temperature calculated from (T _{t , z} = temperature of asphalt mixture at time t according to asphalt depth, T _{(t + Δt), z} = temperature of asphalt mixture at time (t + Δt) along asphalt depth) Can be obtained using a profile. The internal temperature of the asphalt laid varies depending on the thickness of the laying layer and the degree of compaction. The internal temperature of the asphalt mixture is based on the secondary compaction and finishing compaction temperature at which compaction should be sufficiently carried out, and the internal temperature profile is used to estimate the secondary compaction and finishing compaction temperature.

In order to perform the asphalt compaction time prediction method according to an embodiment of the present invention, the time required until the compaction stop temperature is calculated using the temperature profile of the asphalt mixture, which is unknown (S1150). The compaction process is divided into primary compaction, secondary compaction, and final compaction, and the optimum temperature is different for each compaction process. The titration temperature of primary compaction can be 140-160 degreeC, the appropriate temperature of secondary compaction can be 110-130 degreeC, and the appropriate temperature of finishing compaction can be 90-100 degreeC. In the present embodiment, the first compaction stopping temperature was set to 130 ° C, the second compacting stopping temperature was set to 100 ° C, and the finishing compacting stopping temperature was set to 80 ° C. The compaction time can be predicted by calculating the time to reach compaction interruption temperature using the temperature profile. The first compaction temperature end time is estimated using the surface temperature profile, and the second compaction and finish compaction end time is estimated using the internal temperature profile.

3 is a flowchart illustrating a method for predicting asphalt compaction time according to another embodiment of the present invention, and FIG. 4 is a view illustrating a temperature profile and a measured temperature profile in the asphalt compaction time prediction method according to another embodiment of the present invention. to be.

In the asphalt compaction time prediction method according to another embodiment of the present invention, the temperature profile may be measured at the compaction process site to correct the predicted temperature profile.

As shown in Figure 3, in order to implement the asphalt compaction time prediction method according to another embodiment of the present invention, the state information of the asphalt mixture is received (S3110). The asphalt state information includes the type of asphalt mixture, the mixing ratio of the asphalt mixture, the thickness of the asphalt laid, the temperature of the asphalt laid, and the like.

Then, the environment information is input (S3120). The environmental information includes the status information of the site where the asphalt is laid, such as the properties of the asphalt contact surface and the temperature of the asphalt contact surface, and weather information such as air temperature, wind speed, humidity, solar radiation level, and cloud amount. A plurality of environmental parameters are generated according to preset rules using the properties of the asphalt contact surface, wind speed and humidity, solar radiation level and cloud cover.

Next, the thermal conductivity constant of the asphalt mixture is received (S3130). Thermal conductivity constants of asphalt mixtures include conductivity and diffusion rate. Conductivity and diffusion are measured by the probe method.

The temperature profile of the asphalt mixture is calculated using the input asphalt state information, environmental information, and the thermal conductivity constant of the asphalt mixture (S3140).

expression

(T _{1 (t)} = surface temperature of the asphalt mixture at time t,

T _{1 (t + Δt)} = surface temperature of the asphalt mixture at time (t + Δt),

T _{2 (t)} = incremental temperature at time 2,

α = thermal diffusivity of the asphalt mixture,

Δt = time variation,

Δz = change in thickness of the asphalt mixture,

N _bi = bio number,

T _a = ambient temperature,

H _s = influence of solar energy,

a = total absorption of asphalt mixture,

ε = total discharge of asphalt mixture,

surface temperature profile of the asphalt mixture laid by σ = Stephan-Boltzmann constant). The surface temperature profile is used to estimate the first compaction temperature.

As the compacting process proceeds, the temperature profile changes according to the compaction degree.

expression

(T _{t, z} = temperature of the asphalt mixture at time t along the asphalt depth,

T _{(t + Δt), z} = temperature of the asphalt mixture at time t + Δt along the asphalt depth) yields an internal temperature profile of the asphalt mixture that is laid. The internal temperature profile is used to estimate the secondary compaction and finish compaction temperature.

Next, the temperature profile of the asphalt mixture to be installed is measured (S3150). The temperature is measured over time and the depth of the asphalt mixture as the compaction process proceeds. In this example, a surface type probe was used to measure the temperature of the asphalt mixture. A 5 cm diameter surface type probe was used and a dynamic measurement method was applied. The temperature is shown on the general axis of the semilog graph and the time is shown on the log axis. The linear part of the curve is confirmed, and a value indicating the temperature and time at the end of the linear part is confirmed.

The temperature profile of the calculated asphalt mixture is compared with the measured temperature profile of the measured asphalt mixture to correct the temperature profile of the calculated asphalt mixture to a value that minimizes the error between the two profiles (S3160).

4 shows the predicted and measured temperature profiles. The measurements were taken at regular time intervals during compaction during drainage packaging. As shown in FIG. 4, the predicted temperature profile shows a similar pattern to the actual measured temperature. However, due to the error of the initial temperature measurement and the sudden change of the situation of the compaction field condition, the theoretical temperature and the actual measured temperature profile are bound to be in error. Therefore, the calculated temperature profile should be corrected using the temperature profile measured during the compaction process.

The temperature profile calculated by the initial condition and the measured temperature profile are compared to correct the calculated temperature profile with the minimum error. Since an error may occur during the measurement of the actual temperature profile, the error is corrected to a value that minimizes the error between the two profiles, rather than immediately correcting the temperature profile calculated by the actual measured temperature profile value. The minimum value of the root mean square (RMS) value is obtained by comparing the calculated temperature profile with the measured temperature profile to obtain the minimum error value. By using the minimum value of the RMS value, the error can be minimized and a more reliable temperature profile can be obtained.

In the asphalt compaction time prediction method according to another embodiment of the present invention, in order to more quickly correct the calculated temperature profile, only the inversely calculated thermal conductivity and thermal diffusivity may be reflected in the correction.

The thermal conductivity is back-calculated as follows by the measured temperature profile.

--- (식 10)

--- (Equation 10)

(k = thermal conductivity,

Q = calories,

T ₁ = initial measurement temperature,

T ₂ = last measurement temperature,

t ₁ = initial time,

t ₂ = last time)

이므로, 열확산율 역시 측정된 온도 프로파일과 역계산된 열전도율에 의해 역계산될 수 있다. 역계산된 열전도 상수를 재입력받아 온도 프로파일을 다시 산출한다. 온도 프로파일을 산출하기 위해서 식Where the thermal diffusivity α

Therefore, the thermal diffusivity may also be inversely calculated by the measured temperature profile and the inversely calculated thermal conductivity. The temperature profile is recalculated by inputting the inversely calculated thermal conductivity constant. To calculate the temperature profile

(T _{1 (t)} = surface temperature of the asphalt mixture at time t,

T _{1 (t + Δt)} = surface temperature of the asphalt mixture at time (t + Δt),

T _{2 (t)} = incremental temperature at time 2,

α = thermal diffusivity of the asphalt mixture,

Δt = time variation,

Δz = change in thickness of the asphalt mixture,

N _bi = bio number,

T _a = ambient temperature,

H _s = influence of solar energy,

a = total absorption of asphalt mixture,

ε = total discharge of asphalt mixture,

σ = Stefan-Boltzmann's constant)

expression

(T _{t, z} = temperature of the asphalt mixture at time t along the asphalt depth,

T _{(t + Δt), z} = temperature of the asphalt mixture at time t + Δt along the asphalt depth) is used.

Finally, using the temperature profile of the recalculated asphalt mixture, the time required to stop the compaction temperature is recalculated (S3170). The first compaction temperature end time is estimated using the surface temperature profile, and the second compaction and finish compaction end time is estimated using the internal temperature profile.

5 is a block diagram illustrating an apparatus for predicting asphalt compaction time according to an exemplary embodiment of the present invention.

As shown in FIG. 5, the asphalt compaction time predicting apparatus 500 according to an embodiment of the present invention includes an input unit 510, a controller 520, and a display unit 530. The input unit 510 receives state information, environment information, and heat conductivity constants of the asphalt mixture. The state information of the asphalt mixture includes the mixing ratio of the asphalt mixture, the thickness of the asphalt to be laid, the temperature of the asphalt to be laid, and the like. Environmental information includes the nature of the asphalt contact surface, the temperature of the asphalt contact surface, air temperature, wind speed, humidity, solar radiation level, and the like.

The controller 520 calculates the time taken until the temperature value of the asphalt mixture and the compaction stop temperature by using the state information, the environmental information, and the thermal conductivity constant of the asphalt mixture input from the input unit 510. The temperature change of the asphalt mixture depends on the condition of the asphalt mixture, such as the components of the asphalt mixture, the mixing ratio, and the like. In other words, the asphalt mixture has different thermal conductivity depending on its composition and content. This difference in thermal conductivity results in a different time taken for the compaction stop temperature of the asphalt.

The compaction stopping temperature of the asphalt is divided into the first compaction stopping temperature, the second compaction stopping temperature, and the finishing compaction stopping temperature. The first compaction stop temperature can be determined by the surface temperature profile, and the second compaction stop temperature and the finish compaction stop temperature can be determined according to the internal temperature profile of the asphalt mixture. The titration temperature at the time of primary compaction of an asphalt mixture is 140-160 degreeC, and the titration temperature at the time of secondary compaction is 110-130 degreeC. In the present embodiment, the first compaction stop temperature is 130 ° C., and the second compaction stop temperature is 100 ° C., but is not limited thereto. When laying asphalt, finish compaction is performed after the first compaction and the second compaction, and the appropriate temperature at the final compaction is 90 to 100 ° C.

The controller 520 calculates a temperature profile of the asphalt mixture using the input state information, environment information, and thermal conductivity constants of the asphalt mixture. The temperature profile of the resulting asphalt mixture is used to calculate the time it takes for the asphalt mixture to reach compaction temperature. The controller 520 inversely calculates the thermal conductivity constant using the measured temperature profile, and corrects the temperature profile using the inversely calculated thermal conductivity constant.

The display unit 530 displays the time taken until the compaction stop temperature and the compaction end time. By the data displayed on the display unit 530, it is possible to efficiently manage the compaction process time of the asphalt mixture. When the compaction end time elapses, the display unit 530 may sound an alarm or display on the screen to notify that the compaction end time is reached.

[Example]

The asphalt compaction time prediction method described above will be described once again through specific examples.

Apply the asphalt mixture to the pavement with a minimum temperature of 160 ° C. The asphalt compaction time prediction apparatus 500 inputs the type of the asphalt mixture, the mixing ratio of the asphalt mixture, the initial temperature of the asphalt, the surface temperature of the road to be asphalt paved, the atmospheric temperature, the wind speed, the cloud amount, the thermal conductivity constant, and the like. The controller 520 generates a parameter by a preset rule using the input information.

The control unit 520 of the asphalt compaction time predicting apparatus 500 includes the type of the asphalt mixture, the mixing ratio of the asphalt mixture, the initial temperature of the asphalt, the surface temperature of the road to be paved with asphalt, the air temperature, the wind speed, the cloud amount, the thermal conductivity constant. And the like to calculate the temperature profile of the asphalt mixture. The temperature profile of the asphalt mixture laid during the compaction process is measured. The measured temperature profile is compared with the calculated temperature profile and the thermal conductivity constant is reversely calculated and re-input.

The controller 520 calculates the time taken until the temperature of the asphalt mixture reaches the compaction stop temperature by using the calculated surface temperature profile and the internal temperature profile of the asphalt mixture.

The display unit 530 displays the time taken until the compaction interruption temperature and the compaction interruption time calculated according to the conditions of the installation site, and when the compaction interruption time elapses, a sound or a screen is displayed to notify the user. The display unit 530 displays different times according to the first compaction, the second compaction, and the final compaction.

The compaction process is affected by the environment of the asphalt construction site. The cooling rate of the asphalt mixture depends on the surrounding environment in which the asphalt is laid. Factors affecting the maximum density of asphalt in the field include the properties of the asphalt mixture, the temperature of the asphalt mixture at the time of laying, the thickness of the layer, the temperature and rigidity of the asphalt contact surface, the air temperature, the wind speed, the humidity, and the radiation level of solar heat. In the compaction process, the temperature profile of the asphalt mixture can be calculated to predict the temperature change.

By using this, the present invention can predict the time at which the compaction is possible and can perform the compaction process more efficiently. In addition, it is possible to know the appropriate compaction time for the first compaction, the second compaction, the final compaction, the asphalt can have an optimal density, thereby increasing the long-term commonality of the road.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of the present invention in order to facilitate description of the present invention and to facilitate understanding of the present invention and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

500: asphalt compaction time prediction device
510: input unit 520: control unit
530: display unit

Claims (7)

Receiving state information of the asphalt mixture;
Receiving environment information;
Receiving a thermal conductivity constant of the asphalt mixture;
Calculating a temperature profile of the asphalt mixture using state information of the asphalt mixture, the environment information, and a thermal conductivity constant of the asphalt mixture;
The temperature profile of the asphalt mixture is expressed as a temperature value of the asphalt mixture over time, and by substituting the compaction stop temperature set in the temperature profile of the asphalt mixture, calculating the time taken to the set compaction stop temperature; and ,
The compaction stop temperature is divided into the first compaction stop temperature, the second compaction stop temperature and the finishing compaction stop temperature,
The first compaction stop temperature is 140 ~ 160 ℃, the second compaction stop temperature is 110 ~ 130 ℃, the finishing compaction stop temperature is characterized in that 90 ~ 100 ℃ asphalt compaction time prediction method. The method of claim 1,
The state information of the asphalt mixture is asphalt compaction time prediction method, characterized in that the type of asphalt mixture, the mixing ratio of the asphalt mixture, the thickness of the asphalt laid, the temperature of the asphalt laid. The method of claim 1,
The environmental information is the asphalt compaction time prediction method, characterized in that the asphalt surface contact temperature, air temperature, wind speed, cloud amount. The method of claim 1,
Measuring a temperature profile of the asphalt mixture being deposited; And
Comparing the calculated temperature profile of the asphalt mixture with the measured temperature profile of the asphalt mixture to correct the temperature profile of the calculated asphalt mixture to a value that minimizes the error between the two profiles;
The temperature profile of the calibrated asphalt mixture is expressed as a temperature value of the asphalt mixture over time, and substitutes the compaction stop temperature set in the temperature profile of the calibrated asphalt mixture to recalculate the time taken up to the set compaction stop temperature. ,
The compaction stop temperature is divided into the first compaction stop temperature, the second compaction stop temperature and the finishing compaction stop temperature,
The first compaction stop temperature is 140 ~ 160 ℃, the second compaction stop temperature is 110 ~ 130 ℃, the finishing compaction stop temperature is characterized in that 90 ~ 100 ℃ asphalt compaction time prediction method. 5. The method according to any one of claims 1 to 4,
The temperature profile of the asphalt mixture is
expression

(T _{1 (t)} = surface temperature of the asphalt mixture at time t,
T _{1 (t + Δt)} = surface temperature of the asphalt mixture at time (t + Δt),
T _{2 (t)} = incremental temperature at time 2,
α = thermal diffusivity of the asphalt mixture,
Δt = time variation,
Δz = change in thickness of the asphalt mixture,
N _bi = bio number,
T _a = ambient temperature,
H _s = influence of solar energy,
a = total absorption of asphalt mixture,
ε = total discharge of asphalt mixture,
σ = Stefan-Boltzmann constant)
Lt; / RTI >
And the temperature profile is a surface temperature profile. 5. The method according to any one of claims 1 to 4,
The temperature profile of the asphalt mixture is
expression

(T _{t, z} = temperature of the asphalt mixture at time t along the asphalt depth,
T _{(t + Δt), z} = temperature of the asphalt mixture at time (t + Δt) along the asphalt depth),
Asphalt compaction time prediction method, characterized in that the temperature profile is an internal temperature profile. The recording medium which recorded the program which implements the asphalt compaction time prediction method in any one of Claims 1-4.

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