CN114994297A - Method for estimating residual life of snow melting on low-freezing-point ultrathin wearing layer based on snow melting performance - Google Patents
Method for estimating residual life of snow melting on low-freezing-point ultrathin wearing layer based on snow melting performance Download PDFInfo
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- 238000002844 melting Methods 0.000 title claims abstract description 89
- 230000008018 melting Effects 0.000 title claims abstract description 89
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Abstract
A method for estimating the residual life of snow melting on a low-freezing-point ultrathin wearing layer based on snow melting performance relates to a method for estimating the residual life of snow melting on a wearing layer. The invention aims to solve the problem that the service life of an asphalt mixture formed by a low-freezing-point filler cannot be effectively and accurately evaluated only by considering the precipitation of effective components under the influence of a soaking period under the action of various factors in the actual use process of a pavement. The method comprises the following steps: firstly, determining the total concentration of effective components of a low-freezing point filler in a low-freezing point ultrathin wearing layer; secondly, determining the precipitation concentration of the low-freezing-point filler; thirdly, calculating the residual concentration C of the low-freezing-point filler in any position in the Marshall test piece of the asphalt mixture formed by the low-freezing-point filler according to the Fick's two law Residue of (ii) a Fourthly, determining the optimal working concentration; wu, DouDetermining the lowest working concentration; sixthly, establishing a model; and seventhly, estimating the service life. The invention solves the defects in the estimation process of the snow melting life of the low-freezing-point asphalt mixture at the present stage.
Description
Technical Field
The invention relates to a method for estimating the residual life of snow melting on a wearing layer.
Background
The ultra-thin wearing layer with the low freezing point is formed by mixing and paving an asphalt mixture on a pavement by partially or completely replacing mineral powder with a filler with the low freezing point. In the practical use process of the ultra-thin wearing layer with the low freezing point, after the active ingredients begin to be released, the freezing points of ice and snow layers on the contact surface are lowered and begin to melt under the influence of colligative property of the dilute solution. After the water is infiltrated, the effective components in the deep layer gradually start to be released, and under the action of influence factors such as vehicle load, concentration gradient and the like, the effective components released in the deep layer can continuously migrate upwards, so that the continuous snow melting and ice suppressing effects are achieved.
The estimation of the residual life of snow melting on the ultra-thin wearing layer with the low freezing point is established on the basis of research on the migration rule of effective components, and the effective components have various reasons in the precipitation process inside the asphalt mixture, including: temperature, concentration, load, time, etc. Due to the influence of external environmental factors, the internal effective components migrate under the influence of gradient effect and water immersion.
In the existing research, the precipitation concentration of the mixture with the low freezing point directly soaked is mainly selected as the low freezing point life evaluation index in the ice and snow melting life evaluation process, which is inconsistent with the working conditions of the low freezing point asphalt pavement in the actual use process. The service life of the low-freezing-point mixture can not be effectively and accurately evaluated only by considering the precipitation condition of effective components under the influence of the soaking period alone under the action of various factors such as the pumping action of vehicle load, the influence of temperature and the like in the actual use process of the road surface.
Disclosure of Invention
The invention aims to solve the problem that the service life of an asphalt mixture formed by a low-freezing-point filler cannot be effectively and accurately evaluated only by considering the precipitation of effective components under the influence of a soaking period under the action of various factors in the actual use process of a road surface, and provides a method for estimating the residual life of snow melting of a low-freezing-point ultrathin wearing layer based on snow melting performance.
A method for estimating the residual life of snow melting on a low-freezing-point ultrathin wearing layer based on snow melting performance is completed according to the following steps:
firstly, determining the total concentration of effective components of a low-freezing point filler in a low-freezing point ultrathin wearing layer:
firstly, mineral powder is used as a filler to form an asphalt mixture Marshall test piece, then the mineral powder is replaced by the low-freezing-point filler in an equal volume manner to form the asphalt mixture Marshall test piece, and then the actual total mass M of the low-freezing-point filler in the asphalt mixture Marshall test piece formed by the low-freezing-point filler is calculated according to the formula (1) General assembly ；
In the formula: m General assembly The actual total mass of the low freezing point filler is g; m is the mass of a Marshall test piece of the asphalt mixture formed by the low freezing point filler, and 1200g is taken; w is the mass fraction of mineral powder in a Marshall test piece of the asphalt mixture formed by the mineral powder, and is taken as 5 percent; gamma ray 1 The density of the filler with low freezing point is 2.160g/cm 3 ；γ 2 The density of the ore powder is 2.830g/cm 3 ；
Secondly, the method for calculating the total concentration of the low-freezing-point filler in the marshall test piece of the asphalt mixture formed by the low-freezing-point filler comprises the following steps: actual total mass M of filler toward low freezing point General assembly Adding water, and calculating the total concentration C of the low-freezing-point filler in the Marshall test piece of the asphalt mixture formed by the low-freezing-point filler according to the formula (2) General assembly ；
In the formula: n is the molar mass of the low freezing point filler, and 58.5kg/mol is taken; l is the volume of water added, 0.5L is taken, and C is calculated General assembly ＝0.783；
Secondly, determining the precipitation concentration of the low-freezing-point filler:
respectively measuring the electric conductivities of the low-freezing-point filler solutions with the concentrations of 0.05mol/L, 0.1mol/L, 0.15mol/L, 0.2mol/L, 0.25mol/L, 0.3mol/L, 0.35mol/L and 0.4mol/L, establishing the relation between the concentration of the low-freezing-point filler solution and the electric conductivity of the low-freezing-point filler solution by taking the concentration of the low-freezing-point filler solution as a vertical coordinate and the measured electric conductivity as a horizontal coordinate, and fitting to obtain a formula (3), namely the electric conductivity D of the low-freezing-point filler solution and the precipitation concentration C of the low-freezing-point filler Precipitation out of Functional relationship between:
the conductivity D of the low-freezing-point filler solution and the precipitation concentration C of the low-freezing-point filler Precipitation out of The functional relationship between the two is shown in formula (3);
C precipitation out of ＝0.0246×D-0.1249 (3)；
Thirdly, calculating the residual concentration C of the low-freezing point filler in any position in the Marshall test piece of the asphalt mixture formed by the low-freezing point filler according to the Fick's two law Residue of ：
Soaking an asphalt mixture Marshall test piece formed by the low-freezing-point filler into 0.5L of water, and testing the residual concentration C of the low-freezing-point filler in the asphalt mixture Marshall test piece when the test release time is t Residue of The concentration distribution is reduced in a certain gradient, the concentration content of the effective components on the surface layer is low, and the concentration content of the effective components on the deep layer is high, so that the middle position of the prepared test piece is selected, and the residual concentration of the effective components at the position 3cm away from the surface layer is used as the representative value of the residual concentration in the mixture, namely C Residue of C (3, t), of marshall test piecesThe residual effective concentration C (3, t) is calculated according to the formula (4);
in the formula: c (3, t) is the concentration of the low-freezing-point filler at a distance of 3cm from the surface of the Marshall test piece, and the unit is mol/L; c s The concentration of the filler with the low freezing point on the surface of the Marshall test piece, the release time is measured as the conductivity of the water at the time t, and C is calculated according to the formula (3) Precipitation out of ，C Precipitation out Is namely C s The unit is mol/L; c 0 The release concentration of the initial low freezing point filler in the marshall test piece is 0; x is the distance from the surface of the Marshall test piece in cm; t is the release time in units of s; d (t) is the apparent diffusion coefficient of the filler with low freezing point, the standard working condition is 20 ℃, and the diffusion coefficient corresponding to 24 hours of single permeation release under the no-load action is 6.2 multiplied by 10 -6 mol/(L·m·s)；
Fourthly, determining the optimal working concentration of the asphalt mixture Marshall test piece formed by the low-freezing-point filler for melting ice and snow:
preparing low-freezing-point filler solutions with concentrations of 0mol/L, 0.01mol/L, 0.02mol/L, 0.03mol/L, 0.04mol/L, 0.05mol/L, 0.06mol/L, 0.07mol/L, 0.08mol/L, 0.09mol/L and 0.1mol/L, respectively adding ice cubes with the same volume into the low-freezing-point filler solutions with different concentrations, standing at the temperature of 10 +/-1 ℃ for a period of time, and calculating the volume V of the low-freezing-point filler solutions with different concentrations according to a formula (5) Ice melting ；
V Ice melting ＝V-V' (5)；
In the formula: v Ice melting The unit is the ice melting volume of the low freezing point filler solution with different concentrations: mL; v is the total volume of liquid obtained after ice cubes are added into the low freezing point filler solution and placed for a period of time, unit: mL; v' is the volume of the added low freezing point filler solution in units of: mL;
secondly, the concentration of the low freezing point filler solution is taken as the abscissa, and the ice melting volume V of the low freezing point filler solution with different concentrations is taken Ice melting For ordinate, draw different concentrationsThe ice melting capacity curve corresponding to the low freezing point filler solution;
obtaining the following according to the ice melting capacity curve: when the concentration of the low-freezing-point filler solution is 0.04mol/L, the highest point exists in the slope value of the ice melting volume, so that the ice and snow melting capability of the asphalt mixture Marshall test piece formed by the low-freezing-point filler is determined to be excellent when the single release concentration exceeds 0.04 mol/L;
fifthly, determining the lowest working concentration of the asphalt mixture Marshall test piece formed by the low-freezing-point filler for melting ice and snow:
manufacturing a Marshall test piece of the asphalt mixture molded by using the low-freezing-point filler, wherein the low-freezing-point filler accounts for 3.8 percent of the mass of the test piece; immersing the molded asphalt mixture Marshall test piece into 0.5L of water to be released for 0-180 days, testing the release concentration of the low-freezing-point filler every day, and drawing a release period and release concentration curve of the low-freezing-point filler by taking the number of released days as a vertical coordinate and the release concentration of the low-freezing-point filler as a horizontal coordinate; then, the image is subjected to section-by-section derivation, and the slope change value shows that when the concentration is less than 0.01mol/L, the release days exceed 20 days, the slope value is less than-0.001 and is close to zero, and when the slope change value is lower than the concentration limit value, along with the increase of the release days, the release amount of the low-freezing-point filler in the test piece is lower, the snow melting capacity is insufficient, and the service life of melting the ice and snow is prolonged, so that the single release concentration of 0.01mol/L is selected as the lowest working concentration of melting the ice and snow of the test piece;
sixthly, establishing a prediction model of the residual life of the snow melting of the low-freezing-point ultrathin wearing layer:
according to Fick's two law in step III, and through the influence of three main factors of temperature correction, load correction and period correction on the road in the actual road use process, the apparent diffusion coefficient D (t) of the road when the road actually releases the low-freezing-point filler is corrected, see formula (6):
D(t)＝K TIME ×K TEMP ×K LOAD ×D(t 0 ) (6)；
in the formula: k is LOAD Is the load influence coefficient; k TIME The age influence coefficient; k TEMP Is the temperature coefficient of influence; d (t) 0 ) Is diffusion under standard working conditionA coefficient;
firstly, correcting age influence coefficient K TIME ：
Age coefficient of influence K TIME Correcting by adopting a formula (7);
in the formula: t is exposure time, and 1d is taken; t is t 0 The soaking time is; k TIME The age influence coefficient; a is age index, a at 0 ℃ is-1.042, a at 10 ℃ is-0.9906, and a at 20 ℃ is-0.8781;
② correcting the temperature influence coefficient K TEMP ：
Coefficient of influence of temperature K TEMP Correcting by adopting a formula (8);
in the formula: e is the activation energy in the transmission process, and the value of E is 9.33232, kilojoule; r is a gas constant of 8.31451J/mol.K; t is the current temperature and is 293K; t is a unit of 0 Reference temperature, 273K respectively;
k is calculated by the formula (8) TEMP When the temperature is increased by 10 ℃, the correction coefficient is enlarged by 1.15 times;
thirdly, correcting the load influence coefficient K LOAD ：
Normally, the load influence coefficient K is corrected LOAD Calculating according to the formula (9);
K LOAD ＝β×σ γ (9)；
in the formula: beta is the correction coefficient of the number of times of the axle load action,
wherein X 1 The cycle number in a single period is ten thousand; d (t) 0 ') the permeability coefficient of the effective components under the actual measurement load condition, and the unit is mol/(L.m.s); sigma γ Is the load of the road surfaceThe stress ratio correction coefficient of the load size and the road surface damage load,
wherein σ c Is the load stress ratio;
fourthly, the calculation formula of the apparent diffusion coefficient D (t) of the low freezing point filler can be known by combining the formulas (6), (7), (8) and (9) and is shown in the formula (10);
fifth, combining the formulas (4) and (10), the residual concentration C of the low-freezing point filler in the asphalt mixture Marshall test piece formed by the low-freezing point filler Residue of The calculation formula of (2) is shown in formula (11);
seventhly, estimating the service life of the effective components with the low freezing point by combining actual meteorological data:
correcting three factors of age, temperature and load respectively according to a low freezing point filler migration rule, wherein the age influence system reaches an icing number K TIME Referring to the formula (7), the exposure time t is 1d, and the soaking time t 0 Taking 0 deg.C (existing state) at 180d temperature, and-1.042 age index, then K TIME 0.004467; coefficient of influence of temperature K TEMP Calculated using equation (8) where the reference temperature T 0 0 deg.C (273K) and 20 deg.C (293K) for current temperature T TEMP 1.32; correction of the load influence coefficient K LOAD Calculating according to the formula (9), wherein the cyclic load is 30% of ultimate failure load, namely the ratio sigma of the cyclic load to the maximum failure load c 0.3 is taken, 15000 is taken as the cycle number in a single period, X 1 Taking 1.5, D (t) 0 ' diffusion coefficient of 2.13X 10 for the measured load regime -6 mol/(L.m.s); the axial load frequency correction coefficient beta is 0.217 and the stress ratio correction coefficient sigma is respectively obtained γ 5.737, and is finally calculatedLoad correction factor K LOAD Taking 1.247;
finally, the formula (11) is adopted, and the diffusion coefficient D (t) under the standard working condition is adopted 0 ) Is 6.2X 10 -6 Taking the thickness of the ultra-thin wearing layer with the low freezing point as 2cm, namely x is 2cm, and establishing the relation between the residual concentration and the precipitation concentration of the filler with the low freezing point;
secondly, taking 0.01mol/L and 0.04mol/L determined in the fourth step and the fifth step as evaluation indexes of the service life range of the Marshall test piece of the asphalt mixture formed by the low freezing point filler; the mass fraction of the low-freezing-point filler in the test piece is 3.8%; soaking the formed asphalt mixture Marshall test piece into 0.5L of water to release, wherein the residual concentration of the low freezing point filler is lower than 0.01mol/L after 20 days, and therefore, 20d is taken as a laboratory life index;
thirdly, actual life prediction is carried out by combining meteorological data:
combining the laboratory life index with meteorological data information to carry out on-site actual conversion, and carrying out equal-scale conversion on the water addition index and the actual environment precipitation index in the experimental process so as to calculate the actual life index of the ultra-thin wearing layer formed by the low freezing point filler, wherein the formula (12) is shown;
in the formula: d is the estimated life and is expressed in d; l is 1 Adding 500mL of water for 20 days in mL for actually measuring the water adding amount in a laboratory; l is 2 The annual average precipitation after the conversion of the meteorological data,
d is the road surface area, and the actual water immersion area of the test piece is taken
Is 63.62cm 2 (ii) a L is the annual average rainfall, and the average value is 500 mm.
The invention has the advantages that:
the invention considers the separation and release processes of effective components (low-freezing-point filler) in two aspects, on one hand, the internal residual concentration of the asphalt mixture formed by the low-freezing-point filler is selected as the evaluation index of the asphalt mixture formed by the low-freezing-point filler, and the problem of service life estimation caused by the interference of external factors in the actual pavement use process is effectively avoided; on the other hand, the Fick second law is adopted to calculate the residual concentration of the effective components, corresponding diffusion coefficient correction is carried out by combining the aspects of the soaking age, the load pumping action, the migration and release of the effective components under the influence of temperature and the like, and the correction coefficient is corrected and adjusted according to the actual measurement result, so that the residual life of the low-freezing-point asphalt mixture is comprehensively judged, and the defects in the snow melting life estimation process of the low-freezing-point asphalt mixture at the present stage are overcome.
The method can obtain the estimation method of the residual life of the snow melting on the low-freezing-point ultrathin wearing layer based on the snow melting performance.
Drawings
FIG. 1 is a fitted image of conductivity versus precipitate concentration;
FIG. 2 is a fitted image of different periods;
FIG. 3 is a single cycle fit image at different temperatures;
FIG. 4 is a fitting image of the Arrhenius equation;
FIG. 5 is the corresponding ice melting capacities of solutions of different concentrations;
FIG. 6 is a graph of the single release of an asphalt mix molded with a low freezing point filler;
FIG. 7 shows the relationship between residual concentration and released concentration.
Detailed Description
The following examples further illustrate the present invention but are not to be construed as limiting the invention. Modifications and substitutions to methods, procedures, or conditions of the invention may be made without departing from the spirit of the invention.
The first embodiment is as follows: the method for estimating the residual life of the snow melt of the low-freezing-point ultrathin wearing layer based on the snow melt performance is completed according to the following steps:
firstly, determining the total concentration of effective components of a low-freezing point filler in a low-freezing point ultrathin wearing layer:
firstly, mineral powder is used as a filler to form an asphalt mixture Marshall test piece, then the mineral powder is replaced by the low-freezing-point filler in an equal volume manner to form the asphalt mixture Marshall test piece, and then the actual total mass M of the low-freezing-point filler in the asphalt mixture Marshall test piece formed by the low-freezing-point filler is calculated according to the formula (1) General assembly ；
In the formula: m General assembly The actual total mass of the low freezing point filler is g; m is the mass of a Marshall test piece of the asphalt mixture formed by the low freezing point filler, and 1200g is taken; w is the mass fraction of mineral powder in a Marshall test piece of the asphalt mixture formed by the mineral powder, and is taken as 5 percent; gamma ray 1 The density of the filler with low freezing point is 2.160g/cm 3 ；γ 2 The density of the ore powder is 2.830g/cm 3 ；
Secondly, the method for calculating the total concentration of the low-freezing-point filler in the Marshall test piece of the asphalt mixture formed by the low-freezing-point filler comprises the following steps: actual total mass M of filler toward low freezing point General assembly Adding water, and calculating the total concentration C of the low-freezing-point filler in the Marshall test piece of the asphalt mixture formed by the low-freezing-point filler according to the formula (2) General assembly ；
In the formula: n is the molar mass of the low freezing point filler, and 58.5kg/mol is taken; l is the volume of water added, 0.5L is taken, and C is calculated General assembly ＝0.783；
Secondly, determining the precipitation concentration of the low-freezing-point filler:
the electrical conductivity of the low-freezing-point filler solution with the concentration of 0.05mol/L, 0.1mol/L, 0.15mol/L, 0.2mol/L, 0.25mol/L, 0.3mol/L, 0.35mol/L and 0.4mol/L is respectively measured, and the concentration of the low-freezing-point filler solution is used as an ordinate to measureThe conductivity of the low freezing point filler solution is an abscissa, the relationship between the concentration of the low freezing point filler solution and the conductivity of the low freezing point filler solution is established, and fitting is performed to obtain a formula (3), namely the formula (3) is the conductivity D of the low freezing point filler solution and the precipitation concentration C of the low freezing point filler Precipitation out of The functional relationship between them is shown in FIG. 1:
as can be seen from fig. 1: conductivity D of low-freezing-point filler solution and precipitation concentration C of low-freezing-point filler Precipitation out The functional relationship between the two is shown in formula (3);
C precipitation out of ＝0.0246×D-0.1249 (3)；
Thirdly, calculating the residual concentration C of the low-freezing point filler in any position in the Marshall test piece of the asphalt mixture formed by the low-freezing point filler according to the Fick's two law Residue(s) of ：
Soaking an asphalt mixture Marshall test piece formed by the low-freezing-point filler into 0.5L of water, and testing the residual concentration C of the low-freezing-point filler in the asphalt mixture Marshall test piece when the release time is t Residue(s) of The concentration distribution is reduced in a certain gradient, the concentration content of the effective components on the surface layer is low, and the concentration content of the effective components on the deep layer is high, so that the middle position of the prepared test piece is selected, and the residual concentration of the effective components at the position 3cm away from the surface layer is used as the representative value of the residual concentration in the mixture, namely C Residue of C (3, t), wherein the residual effective concentration C (3, t) in the marshall test piece is calculated according to formula (4);
in the formula: c (3, t) is the concentration of the low-freezing-point filler at a distance of 3cm from the surface of the Marshall test piece, and the unit is mol/L; c s The concentration of the filler with the low freezing point on the surface of the Marshall test piece, the release time is measured as the conductivity of the water at the time t, and C is calculated according to the formula (3) Precipitation out ，C Precipitation out of Is namely C s The unit is mol/L; c 0 The release concentration of the initial low freezing point filler in the marshall test piece is 0; x is the distance from the surface of the Marshall test piece in cm; t is the release time in units of s; d (t) is the appearance of a low freezing point fillerThe diffusion coefficient is 6.2 multiplied by 10, the standard working condition is 20 ℃, and the diffusion coefficient corresponding to 24 hours of single permeation and release under the no-load action -6 mol/(L·m·s)；
Fourthly, determining the optimal working concentration of the asphalt mixture Marshall test piece formed by the low-freezing-point filler for melting ice and snow:
preparing low-freezing-point filler solutions with concentrations of 0mol/L, 0.01mol/L, 0.02mol/L, 0.03mol/L, 0.04mol/L, 0.05mol/L, 0.06mol/L, 0.07mol/L, 0.08mol/L, 0.09mol/L and 0.1mol/L, respectively adding ice cubes with the same volume into the low-freezing-point filler solutions with different concentrations, standing at the temperature of 10 +/-1 ℃ for a period of time, and calculating the volume V of the low-freezing-point filler solutions with different concentrations according to a formula (5) Ice melting ；
V Ice melting ＝V-V' (5)；
In the formula: v Ice melting The unit is the ice melting volume of the low freezing point filler solution with different concentrations: mL; v is the total volume of liquid obtained after ice cubes are added into the low freezing point filler solution and placed for a period of time, unit: mL; v' is the volume of the added low freezing point filler solution in units of: mL;
secondly, the concentration of the low freezing point filler solution is taken as the abscissa, and the volume V of the low freezing point filler solution with different concentrations for melting ice is taken Ice melting Drawing ice melting capacity curves corresponding to the low freezing point filler solutions with different concentrations as a vertical coordinate;
obtaining the following according to the ice melting capacity curve: when the concentration of the low-freezing-point filler solution is 0.04mol/L, the highest point exists in the slope value of the ice melting volume, so that the ice and snow melting capability of the asphalt mixture Marshall test piece formed by the low-freezing-point filler is determined to be excellent when the single release concentration exceeds 0.04 mol/L;
fifthly, determining the lowest working concentration of the asphalt mixture Marshall test piece formed by the low-freezing-point filler for melting ice and snow:
manufacturing a Marshall test piece of the asphalt mixture molded by using the low-freezing-point filler, wherein the low-freezing-point filler accounts for 3.8 percent of the mass of the test piece; immersing the molded asphalt mixture Marshall test piece into 0.5L of water to be released for 0-180 days, testing the release concentration of the low-freezing-point filler every day, and drawing a release period and release concentration curve of the low-freezing-point filler by taking the number of released days as a vertical coordinate and the release concentration of the low-freezing-point filler as a horizontal coordinate; then, the image is subjected to section-by-section derivation, and the slope change value shows that when the concentration is less than 0.01mol/L, the release days exceed 20 days, the slope value is less than-0.001 and is close to zero, and when the slope change value is lower than the concentration limit value, along with the increase of the release days, the release amount of the low-freezing-point filler in the test piece is lower, the snow melting capacity is insufficient, and the service life of melting the ice and snow is prolonged, so that the single release concentration of 0.01mol/L is selected as the lowest working concentration of melting the ice and snow of the test piece;
sixthly, establishing a prediction model of the residual life of the snow melting of the low-freezing-point ultrathin wearing layer:
according to Fick's two law in step III, and through the influence of three main factors of temperature correction, load correction and period correction on the road in the actual road use process, the apparent diffusion coefficient D (t) of the road when the road actually releases the low-freezing-point filler is corrected, see formula (6):
D(t)＝K TIME ×K TEMP ×K LOAD ×D(t 0 ) (6)；
in the formula: k is LOAD Is the load influence coefficient; k TIME The age influence coefficient; k TEMP Is the temperature coefficient of influence; d (t) 0 ) Is the diffusion coefficient under the standard working condition;
firstly, correcting age influence coefficient K TIME ：
Age coefficient of influence K TIME Correcting by adopting a formula (7);
in the formula: t is exposure time, 1d is taken; t is t 0 The soaking time is; k is TIME The age influence coefficient; a is age index, a at 0 ℃ is-1.042, a at 10 ℃ is-0.9906, and a at 20 ℃ is-0.8781;
② correcting the temperature influence coefficient K TEMP ：
Coefficient of influence of temperature K TEMP By using the formula (8)Correcting;
in the formula: e is the activation energy in the transmission process, and the value of E is 9.33232, kilojoule; r is a gas constant of 8.31451J/mol.K; t is the current temperature and is 293K; t is 0 Reference temperature, 273K respectively;
k is calculated by the formula (8) TEMP When the temperature is increased by 10 ℃, the correction coefficient is enlarged by 1.15 times;
thirdly, correcting the load influence coefficient K LOAD ：
Normally, the load influence coefficient K is corrected LOAD Calculating according to the formula (9);
K LOAD ＝β×σ γ (9)；
in the formula: beta is the correction coefficient of the number of times of the axle load action,
wherein X 1 The cycle number in a single period is ten thousand; d (t) 0 ') the permeability coefficient of the effective components under the actual measurement load condition, and the unit is mol/(L.m.s); sigma γ The stress ratio correction coefficient of the load of the road surface and the damage load of the road surface,
wherein sigma c Is the load stress ratio;
fourthly, the calculation formula of the apparent diffusion coefficient D (t) of the low freezing point filler can be known by combining the formulas (6), (7), (8) and (9) and is shown in the formula (10);
fifth, the residual concentration C of the low-freezing-point filler in the asphalt mixture Marshall test piece formed by the low-freezing-point filler can be known by integrating the formulas (4) and (10) Residue of The calculation formula is shown in formula (1)1)；
Seventhly, estimating the service life of the effective components with the low freezing point by combining actual meteorological data:
firstly, according to the migration rule of the low freezing point filler, three factors of age, temperature and load are respectively corrected, wherein the age influence system reaches the icing number K TIME Referring to the formula (7), the exposure time t is 1d, and the soaking time t 0 Taking temperature of 180 days as 0 deg.C (in current state), age index as-1.042, then K TIME 0.004467; coefficient of influence of temperature K TEMP Calculated using equation (8) where the reference temperature T 0 0 deg.C (273K) and 20 deg.C (293K) for current temperature T TEMP 1.32; correction of the load influence coefficient K LOAD Calculating according to the formula (9), wherein the cyclic load is 30% of ultimate failure load, namely the ratio sigma of the cyclic load to the maximum failure load c 0.3 is taken, 15000 is taken as the cycle number in a single period, X 1 Take 1.5, D (t) 0 ' diffusion coefficient of 2.13X 10 for the measured load regime -6 mol/(L.m.s); the axial load frequency correction coefficient beta is 0.217 and the stress ratio correction coefficient sigma is respectively obtained γ 5.737, and finally obtaining a load correction coefficient K through calculation LOAD Taking 1.247;
finally, the formula (11) is adopted, and the diffusion coefficient D (t) under the standard working condition is adopted 0 ) Is 6.2X 10 -6 Taking the thickness of the ultra-thin wearing layer with the low freezing point as 2cm, namely x is 2cm, and establishing the relation between the residual concentration and the precipitation concentration of the filler with the low freezing point;
secondly, taking 0.01mol/L and 0.04mol/L determined in the fourth step and the fifth step as evaluation indexes of the service life range of the Marshall test piece of the asphalt mixture formed by the low-freezing-point filler; the mass fraction of the low-freezing-point filler in the test piece is 3.8%; the formed asphalt mixture Marshall test piece is immersed into 0.5L of water to be released, and the residual concentration of the low freezing point filler is lower than 0.01mol/L after 20 days, so 20d is taken as the service life index of a laboratory;
thirdly, combining meteorological data to predict the actual service life:
combining the laboratory life index with meteorological data information to carry out on-site actual conversion, and carrying out equal-scale conversion on the water addition index and the actual environment precipitation index in the experimental process so as to calculate the actual life index of the ultra-thin wearing layer formed by the low freezing point filler, wherein the formula (12) is shown;
in the formula: d is the estimated life and is expressed in d; l is a radical of an alcohol 1 Adding 500mL of water for laboratory actual measurement, wherein the unit is mL for 20 days; l is 2 The annual average precipitation after the conversion of the meteorological data,
d is the area of the road surface, and the actual immersion area of the test piece is taken to be 90 mm;
is 63.62cm 2 (ii) a L is the annual average rainfall, and the average value is 500 mm.
The second embodiment is as follows: the first difference between the present embodiment and the present embodiment is: the low freezing point filler is anti-ice-snow melting low freezing point filler ZG-F-I. Other steps are the same as in the first embodiment.
The third concrete implementation mode: the present embodiment differs from the first or second embodiment in that: taking 1200g of m in the first step; in the first step, 0.5L is taken as L. The other steps are the same as in the first or second embodiment.
The fourth concrete implementation mode: the difference between this embodiment and one of the first to third embodiments is as follows: the concentration of the low freezing point filler solution in the second step is respectively 0.05mol/L, 0.1mol/L, 0.15mol/L, 0.2mol/L, 0.25mol/L, 0.3mol/L, 0.35mol/L and 0.4 mol/L. The other steps are the same as those in the first to third embodiments.
The fifth concrete implementation mode: the difference between this embodiment and one of the first to fourth embodiments is: the concentration of the low freezing point filler solution in the fourth step is respectively 0mol/L, 0.01mol/L, 0.02mol/L, 0.03mol/L, 0.04mol/L, 0.05mol/L, 0.06mol/L, 0.07mol/L, 0.08mol/L, 0.09mol/L and 0.1 mol/L. The other steps are the same as those in the first to fourth embodiments.
The following examples were used to demonstrate the beneficial effects of the present invention:
example 1: a method for estimating the residual life of snow melting on a low-freezing-point ultrathin wearing layer based on snow melting performance is completed according to the following steps:
firstly, determining the total concentration of effective components of a low-freezing point filler in a low-freezing point ultrathin wearing layer:
firstly, mineral powder is used as a filler to form an asphalt mixture Marshall test piece, then the mineral powder is replaced by the low-freezing-point filler in an equal volume manner to form the asphalt mixture Marshall test piece, and then the actual total mass M of the low-freezing-point filler in the asphalt mixture Marshall test piece formed by the low-freezing-point filler is calculated according to the formula (1) General assembly ；
In the formula: m General assembly The actual total mass of the low freezing point filler is g; m is the mass of a Marshall test piece of the asphalt mixture formed by the low freezing point filler, and 1200g is taken; w is the mass fraction of mineral powder in a Marshall test piece of the asphalt mixture formed by the mineral powder, and is taken as 5 percent; gamma ray 1 The density of the filler with low freezing point is 2.160g/cm 3 ；γ 2 The density of the ore powder is 2.830g/cm 3 ；
Secondly, the method for calculating the total concentration of the low-freezing-point filler in the marshall test piece of the asphalt mixture formed by the low-freezing-point filler comprises the following steps: actual total mass M of filler toward low freezing point General assembly Adding water, and calculating the total concentration C of the low-freezing-point filler in the Marshall test piece of the asphalt mixture formed by the low-freezing-point filler according to the formula (2) General assembly ；
In the formula: n is the molar mass of the low freezing point filler, and 58.5kg/mol is taken; l is the volume of water added, 0.5L is taken, and C is calculated General (1) ＝0.783；
Secondly, determining the precipitation concentration of the low-freezing-point filler:
respectively measuring the electric conductivities of the low-freezing-point filler solutions with the concentrations of 0.05mol/L, 0.1mol/L, 0.15mol/L, 0.2mol/L, 0.25mol/L, 0.3mol/L, 0.35mol/L and 0.4mol/L, establishing the relation between the concentration of the low-freezing-point filler solution and the electric conductivity of the low-freezing-point filler solution by taking the concentration of the low-freezing-point filler solution as a vertical coordinate and the measured electric conductivity as a horizontal coordinate, and fitting to obtain a formula (3), namely the electric conductivity D of the low-freezing-point filler solution and the precipitation concentration C of the low-freezing-point filler Precipitation out of Functional relationship between:
C precipitation out of ＝0.0246×D-0.1249 (3)；
Thirdly, calculating the residual concentration C of the low-freezing point filler in any position in the Marshall test piece of the asphalt mixture formed by the low-freezing point filler according to the Fick's two law Residue of ：
Soaking an asphalt mixture Marshall test piece formed by the low-freezing-point filler into 0.5L of water, and testing the residual concentration C of the low-freezing-point filler in the asphalt mixture Marshall test piece when the test release time is t Residue of The concentration distribution of the mixture is reduced in a certain gradient, the concentration content of the effective components on the surface layer is low, the concentration content of the effective components on the deep layer is high, so that the middle position of a prepared test piece is selected, and the residual concentration of the effective components at the position 3cm away from the surface layer is used as the representative value of the residual concentration in the mixture, namely C Residue of C (3, t), wherein the residual effective concentration C (3, t) in the marshall specimen is calculated according to equation (4);
in the formula: c (3, t) is the concentration of the low freezing point filler at a distance of 3cm from the surface of the Marshall test piece, and the unit is mol/L; c s Is lower than the surface of the Marshall specimenFreezing point filler concentration, measuring the electrical conductivity of water with release time at t moment, and calculating C according to formula (3) Precipitation out ，C Precipitation out of Is namely C s The unit is mol/L; c 0 The release concentration of the initial low freezing point filler in the marshall test piece is 0; x is the distance from the surface of the Marshall test piece in cm; t is the release time in units of s; d (t) is the apparent diffusion coefficient of the filler with low freezing point, the standard working condition is 20 ℃, and the diffusion coefficient corresponding to 24 hours of single permeation release under the no-load action is 6.2 multiplied by 10 -6 mol/(L·m·s)；
Fourthly, determining the optimal working concentration of the asphalt mixture Marshall test piece formed by the low-freezing-point filler for melting ice and snow:
preparing low-freezing-point filler solutions with concentrations of 0mol/L, 0.01mol/L, 0.02mol/L, 0.03mol/L, 0.04mol/L, 0.05mol/L, 0.06mol/L, 0.07mol/L, 0.08mol/L, 0.09mol/L and 0.1mol/L, respectively adding ice cubes with the same volume into the low-freezing-point filler solutions with different concentrations, standing at the temperature of 10 +/-1 ℃ for a period of time, and calculating the volume V of the low-freezing-point filler solutions with different concentrations according to a formula (5) Ice melting ；
V Ice melting ＝V-V' (5)；
In the formula: v Ice melting The unit is the ice melting volume of the low freezing point filler solution with different concentrations: mL; v is the total volume of liquid obtained after ice cubes are added into the low freezing point filler solution and placed for a period of time, unit: mL; v' is the volume of the added low freezing point filler solution in units of: mL;
secondly, the concentration of the low freezing point filler solution is taken as the abscissa, and the volume V of the low freezing point filler solution with different concentrations for melting ice is taken Ice melting Drawing ice melting capacity curves corresponding to the low freezing point filler solutions with different concentrations as a vertical coordinate;
thirdly, obtaining the following according to the ice melting capacity curve: when the concentration of the low-freezing-point filler solution is 0.04mol/L, the highest point exists in the slope value of the ice melting volume, so that the ice and snow melting capability of the asphalt mixture Marshall test piece formed by the low-freezing-point filler is determined to be excellent when the single release concentration exceeds 0.04 mol/L;
fifthly, determining the lowest working concentration of the asphalt mixture Marshall test piece formed by the low-freezing-point filler for melting ice and snow:
manufacturing an asphalt mixture Marshall test piece molded by using a low-freezing-point filler, wherein the low-freezing-point filler accounts for 3.8% of the mass of the test piece; immersing the molded asphalt mixture Marshall test piece into 0.5L of water to release for 0-180 days, testing the release concentration of the low-freezing-point filler every day, and drawing a release period and release concentration curve of the low-freezing-point filler by taking the number of days of release as a vertical coordinate and the release concentration of the low-freezing-point filler as a horizontal coordinate; then, the image is derived segment by segment, and the slope change value shows that when the concentration is less than 0.01mol/L, the release days exceed 20 days, the slope value is less than-0.001 and is close to zero, and when the slope change value is lower than the concentration limit value, along with the increase of the release days, the release amount of the low freezing point filler in the test piece is lower, the snow melting capacity is insufficient, and the service life of melting the ice and snow is reached, so that the single release concentration of 0.01mol/L is selected as the lowest working concentration of melting the ice and snow of the test piece, as shown in fig. 5 and fig. 6;
sixthly, establishing a prediction model of the residual life of the snow melt of the low-freezing-point ultrathin wearing layer:
according to Fick's two law in step III, and through the influence of three main factors of temperature correction, load correction and period correction on the road in the actual road use process, the apparent diffusion coefficient D (t) of the road when the road actually releases the low-freezing-point filler is corrected, see formula (6):
D(t)＝K TIME ×K TEMP ×K LOAD ×D(t 0 ) (6)；
in the formula: k is LOAD Is the load influence coefficient; k TIME The age influence coefficient; k TEMP Is the temperature coefficient of influence; d (t) 0 ) Is the diffusion coefficient under the standard working condition;
firstly, correcting age influence coefficient K TIME ：
The anion of the low-freezing-point filler is chloride ion, the apparent diffusion coefficient of the chloride ion in the concrete is obviously reduced along with the increase of the exposure age, meanwhile, the difficulty degree of the chloride ion diffusion at different depths is influenced by the local water saturation degree, and the diffusion coefficients of the chloride ion at different depths are different. From the results of laboratory tests and the prior structural survey, the diffusion coefficient and the time are approximately in a linear change relationship in a double logarithmic coordinate system; therefore, the time-varying relation of the diffusion coefficient is also usually expressed by a power function, and the fitting result is shown in fig. 2 and 3;
age coefficient of influence K TIME Correcting by adopting a formula (7);
in the formula: t is exposure time, 1d is taken; t is t 0 The soaking time is; k is TIME The age influence coefficient;
the residual content of effective components in the mixture with effective components in four periods of 7d, 14d, 21d and 28d under different temperature conditions of 0 ℃, 10 ℃, 20 ℃ and the like is actually measured by a Marshall test piece of the asphalt mixture molded by using the low freezing point filler, and is shown in tables 1-4;
TABLE 17 residual concentrations of active principle after action at different temperatures and depths
TABLE 214 d residual concentrations of active ingredient at various temperatures and depths after exposure
TABLE 321 d residual concentrations of active ingredient at different temperatures and depths after Effect
TABLE 428 d residual concentrations of active ingredient at various temperatures and depths after application
Calculating the permeability coefficient of the effective component according to the residual concentration of the effective component, namely, performing function fitting by using a power function image through the effective component of a fixed section in unit time, thereby solving the undetermined coefficient alpha and further calculating K by a formula TIME See FIG. 3; FIG. 3 is the result of the power function image fitting, wherein the undetermined coefficient α is shown in Table 5;
TABLE 5 fitting values of age index α at different temperatures
From the fitting data results, the fitting coefficient at 20 ℃ is-0.8781, the fitting coefficient at 10 ℃ is-0.9906, and the fitting coefficient at 0 ℃ is-1.042, i.e., the fitting coefficient gradually decreases with the increase of the period, and the period correction coefficient gradually decreases. Wherein the fitting relation of the correction coefficients under different temperature working conditions is shown in figure 4;
thus, it can be seen that: a is age index, a at 0 ℃ is-1.042, a at 10 ℃ is-0.9906, and a at 20 ℃ is-0.8781;
② correcting the temperature influence coefficient K TEMP ：
The temperature change of the service environment of the asphalt mixture formed by the low-freezing-point filler has a remarkable influence on the diffusion of chloride ions in the asphalt mixture, and the diffusion speed of the ions is accelerated due to the increase of the temperature. The effect of temperature on the chloride diffusion coefficient can generally be quantitatively described by the Arrhenius equation:
in the formula: k is a reaction rate constant at a temperature T; a is a pre-exponential factor, also called Arrhenius constant, with the same unit as k; e is activation energy, and the unit is kJ/mol; t is the absolute temperature;
in order to solve the activation energy in the solution, the conductivity of the solution at different temperatures and different periods needs to be tested, and the activation energy of the solution is converted through the conductivity; drawing a fitting image by taking lnk as a vertical coordinate and 1/T as a horizontal coordinate, and calculating the slope K of the image 1 The calculation results are shown in fig. 4; the activation energy E ═ K of the solution 1 R (R is Boltzmann constant), and E ═ K after simplification 1 *(-0.0799). Substituting the fitting result into a formula to calculate the activation energy, and calculating the temperature influence coefficient K by using an empirical formula of the temperature-influenced migration coefficient of the salt TEMP ；
Therefore, the temperature coefficient of influence K TEMP Correcting by adopting a formula (8);
in the formula: e is the activation energy in the transmission process, and the value of E is 9.33232, kilojoule; r is a gas constant of 8.31451J/mol.K; t is the current temperature and is 293K; t is 0 Reference temperature, 273K respectively;
k is calculated by the formula (8) TEMP When the temperature is increased by 10 ℃, the correction coefficient is enlarged by 1.15 times;
thirdly, correcting the load influence coefficient K LOAD ：
In general, a load influence coefficient is often introduced into a chloride ion migration and release model considering stress influence to clarify the influence of stress, and the ratio of the chloride ion diffusion coefficient under a stress state to the chloride ion diffusion coefficient under a non-stress state (relative chloride ion diffusion coefficient) is defined as a load influence coefficient K LOAD Calculating according to the formula (9);
K LOAD ＝β×σ γ (9)；
wherein beta is the correction coefficient of the number of times of axle load action, sigma γ The magnitude of the load on the road surface and the stress of the road surface damaging loadA ratio correction factor;
the parameter value determination process is as follows: first, the ultimate load condition parameters were selected according to the unconfined compressive strength values of the asphalt marshall test pieces tested by the UTM universal tester to be 45.414 KN. And then, replacing the pressure head, ensuring that the pressure head can go deep into the upper sleeve for measurement, and obtaining the ultimate compression resistance value of the Marshall test piece which is 24KN after equivalent conversion. And (3) respectively taking 30%, 50% and 80% of the ultimate failure load to test the residual concentration inside the low-freezing-point asphalt mixture test piece under the load action, and the results are shown in tables 6 and 7.
TABLE 6 residual concentration of active ingredient under different cyclic load magnitude
TABLE 7 residual concentration of active principle at different cyclic loading times
Fitting effective component permeability coefficient D (t) value solved by the concentration change value in the unit period to obtain the load action times (X) 1 Ten thousand times and permeability coefficient (Y) 1 /*10 -7 ) The fitting formula between satisfies the linear relation: y is 1 ＝3.0845X 1 That is, every 10000 times of axle load action, the axle load correction coefficient β can be expressed as:
the load stress ratio (sigma) is obtained by the same method c ) And permeability coefficient (Y) 1 /*10 -7 ) The fitting formula between satisfies the exponential function relationship:
stress ratio correction coefficient sigma γ Can be expressed as:
the corrected estimating formula of the residual life of the ice and snow melting is as follows:
the calculation formula of the apparent diffusion coefficient D (t) of the low-freezing-point filler can be seen in the formula (10) by combining the formulas (6), (7), (8) and (9);
by combining the formulas (4) and (10), the residual concentration C of the low-freezing-point filler in the Marshall test piece of the asphalt mixture formed by the low-freezing-point filler Residue(s) of The calculation formula of (2) is shown in formula (11);
in the formula: beta is the correction coefficient of the number of times of the axle load action,
wherein X 1 The cycle number in a single period is ten thousand; d (t) 0 ') the permeability coefficient of the effective components under the actual measurement load condition, and the unit is mol/(L.m.s); sigma γ The stress ratio correction coefficient of the load of the road surface and the damage load of the road surface,
wherein sigma c Is the load stress ratio;
seventhly, estimating the service life of the effective components with the low freezing point by combining actual meteorological data:
correcting three factors of age, temperature and load respectively according to a low freezing point filler migration rule, wherein the age influence system reaches an icing number K TIME Referring to the formula (7), the exposure time t is 1d, and the soaking time t 0 Taking 0 deg.C (processed) at 180 days for storageThe term index is-1.042, then K TIME 0.004467; coefficient of influence of temperature K TEMP Calculated using equation (8) where the reference temperature T 0 0 deg.C (273K) and 20 deg.C (293K) for current temperature T TEMP 1.32; correction of the load influence coefficient K LOAD Calculating according to the formula (9), wherein the cyclic load is 30% of ultimate failure load, namely the ratio sigma of the cyclic load to the maximum failure load c Taking 0.3, and taking 15000 times as the cycle number in a single period, X 1 Taking 1.5, D (t) 0 ' diffusion coefficient of 2.13X 10 for the measured load regime -6 mol/(L.m.s); the axial load frequency correction coefficient beta is 0.217 and the stress ratio correction coefficient sigma is respectively obtained γ To 5.737, the load correction factor K is finally calculated according to the formula (9) LOAD Taking 1.247;
finally, the formula (11) is adopted, and the diffusion coefficient D (t) under the standard working condition is adopted 0 ) Is 6.2X 10 -6 Taking the thickness of the ultra-thin wearing layer with the low freezing point as 2cm, namely x is 2cm, establishing the relation between the residual concentration and the precipitation concentration of the low freezing point filler, and showing in a figure 7;
secondly, taking 0.01mol/L and 0.04mol/L determined in the fourth step and the fifth step as evaluation indexes of the service life range of the Marshall test piece of the asphalt mixture formed by the low freezing point filler; the mass fraction of the low-freezing-point filler in the test piece is 3.8%; the formed asphalt mixture Marshall test piece is immersed into 0.5L of water to be released, the residual concentration of the low freezing point filler is lower than 0.01mol/L after 20 days, and therefore 20d is taken as a laboratory life index, as shown in figure 6;
thirdly, actual life prediction is carried out by combining meteorological data:
combining the laboratory life index with meteorological data information to carry out on-site actual conversion, and carrying out equal-scale conversion on the water addition index and the actual environment precipitation index in the experimental process so as to calculate the actual life index of the ultra-thin wearing layer formed by the low freezing point filler, wherein the formula (12) is shown;
in the formula: d is the estimated life, and the unit is d; l is a radical of an alcohol 1 Adding 500mL of water for 20 days in mL for actually measuring the water adding amount in a laboratory; l is 2 The annual average precipitation after the conversion of the meteorological data,
d is the area of the road surface, and the actual immersion area of the test piece is taken to be 90 mm;
is 63.62cm 2 (ii) a L is the annual average rainfall, and the average value is 500 mm.
In the embodiment, the water adding amount is 500mL/d in a single day when a single seepage process is carried out, and the service life is accumulated for 20 days; the total amount of water added in the experiment is 10000 mL; combining the annual weather data of 2020 areas of Harbin city of Heilongjiang province, wherein the rainy days account for 68 days, the snowy days account for 6 days, the average rainfall capacity of the year is 400-600 mm, the median value is 500mm, and the cumulative water addition is calculated to be 3179.25 mL/year; after the equivalent weight is converted into the actual condition, the service life of the asphalt mixture with the low-freezing-point filler accounting for 3.8 percent of the mass fraction of the test piece can reach 3.15 years.
The low freezing point filler described in example 1 is an anti-icing/snowmelt low freezing point filler ZG-F-I, purchased from harbin chenopodiaceae traffic technology co.
Claims (5)
1. A method for estimating the residual life of snow melting on a low-freezing-point ultrathin wearing layer based on snow melting performance is characterized by comprising the following steps of:
firstly, determining the total concentration of effective components of a low-freezing point filler in a low-freezing point ultrathin wearing layer:
firstly, mineral powder is used as a filler to form an asphalt mixture Marshall test piece, then the mineral powder is replaced by the low-freezing-point filler in an equal volume manner to form the asphalt mixture Marshall test piece, and then the actual total mass M of the low-freezing-point filler in the asphalt mixture Marshall test piece formed by the low-freezing-point filler is calculated according to the formula (1) General assembly ；
In the formula: m General assembly The actual total mass of the low freezing point filler is in g; m is the mass of a Marshall test piece of the asphalt mixture molded by the low-freezing-point filler; w is the mass fraction of mineral powder in a Marshall test piece of the asphalt mixture formed by the mineral powder, and is taken as 5 percent; gamma ray 1 The density of the filler with low freezing point is 2.160g/cm 3 ；γ 2 The density of the ore powder is 2.830g/cm 3 ；
Secondly, the method for calculating the total concentration of the low-freezing-point filler in the marshall test piece of the asphalt mixture formed by the low-freezing-point filler comprises the following steps: actual total mass M of filler toward low freezing point General assembly Adding water, and calculating the total concentration C of the low-freezing-point filler in the Marshall test piece of the asphalt mixture formed by the low-freezing-point filler according to the formula (2) General assembly ；
In the formula: n is the molar mass of the low freezing point filler, and 58.5kg/mol is taken; l is the volume of water added, calculated, C General assembly ＝0.783；
Secondly, determining the precipitation concentration of the low-freezing-point filler:
respectively measuring the conductivity of the low-freezing-point filler solution, establishing the relationship between the concentration of the low-freezing-point filler solution and the conductivity of the low-freezing-point filler solution by taking the concentration of the low-freezing-point filler solution as a vertical coordinate and the measured conductivity as a horizontal coordinate, and fitting to obtain a formula (3), namely the formula (3) which is the conductivity D of the low-freezing-point filler solution and the precipitation concentration C of the low-freezing-point filler Precipitation out of Functional relationship between:
conductivity D of low-freezing-point filler solution and precipitation concentration C of low-freezing-point filler Precipitation out of The functional relationship between the two is shown in formula (3);
C precipitation out of ＝0.0246×D-0.1249 (3)；
Thirdly, calculating the Marshall of the asphalt mixture formed by the low freezing point filler according to the Fick's two lawResidual concentration C of low-freezing point filler in any position in test piece Residue of ：
Soaking an asphalt mixture Marshall test piece formed by the low-freezing-point filler into 0.5L of water, and testing the residual concentration C of the low-freezing-point filler in the asphalt mixture Marshall test piece when the release time is t Residue(s) of The concentration distribution is reduced in a certain gradient, the concentration content of the effective components on the surface layer is low, and the concentration content of the effective components on the deep layer is high, so that the middle position of the prepared test piece is selected, and the residual concentration of the effective components at the position 3cm away from the surface layer is used as the representative value of the residual concentration in the mixture, namely C Residue of C (3, t), wherein the residual effective concentration C (3, t) in the marshall specimen is calculated according to equation (4);
in the formula: c (3, t) is the concentration of the low-freezing-point filler at a distance of 3cm from the surface of the Marshall test piece, and the unit is mol/L; c s The concentration of the filler with the low freezing point on the surface of the Marshall test piece, the release time is measured as the conductivity of the water at the time t, and C is calculated according to the formula (3) Precipitation out ，C Precipitation out of Is namely C s The unit is mol/L; c 0 The release concentration of the initial low freezing point filler in the marshall test piece is 0; x is the distance from the surface of the Marshall test piece in cm; t is the release time in units of s; d (t) is the apparent diffusion coefficient of the filler with low freezing point, the standard working condition is 20 ℃, and the diffusion coefficient corresponding to 24 hours of single permeation release under the no-load action is 6.2 multiplied by 10 -6 mol/(L·m·s)；
Fourthly, determining the optimal working concentration of the asphalt mixture Marshall test piece formed by the low-freezing-point filler for melting ice and snow:
preparing a low-freezing-point filler solution, respectively adding ice cubes with the same volume into the low-freezing-point filler solutions with different concentrations, standing at the temperature of 10 +/-1 ℃ for a period of time, and calculating the ice melting volume V of the low-freezing-point filler solutions with different concentrations according to a formula (5) Ice melting ；
V Ice melting ＝V-V' (5)；
In the formula: v Ice melting The unit of the volume of the ice melting of the low freezing point filler solution with different concentrations is as follows: mL; v is the total volume of liquid obtained after ice cubes are added into the low freezing point filler solution and placed for a period of time, unit: mL; v' is the volume of the added low freezing point filler solution, unit: mL;
secondly, the concentration of the low freezing point filler solution is taken as the abscissa, and the volume V of the low freezing point filler solution with different concentrations for melting ice is taken Ice melting Drawing ice melting capacity curves corresponding to the low freezing point filler solutions with different concentrations as a vertical coordinate;
obtaining the following according to the ice melting capacity curve: when the concentration of the low-freezing-point filler solution is 0.04mol/L, the highest point exists in the slope value of the ice melting volume, so that the ice and snow melting capability of the asphalt mixture Marshall test piece formed by the low-freezing-point filler is determined to be excellent when the single release concentration exceeds 0.04 mol/L;
fifthly, determining the lowest working concentration of the asphalt mixture Marshall test piece formed by the low-freezing-point filler for melting ice and snow:
manufacturing an asphalt mixture Marshall test piece molded by using a low-freezing-point filler, wherein the low-freezing-point filler accounts for 3.8% of the mass of the test piece; immersing the molded asphalt mixture Marshall test piece into 0.5L of water to release for 0-180 days, testing the release concentration of the low-freezing-point filler every day, and drawing a release period and release concentration curve of the low-freezing-point filler by taking the number of days of release as a vertical coordinate and the release concentration of the low-freezing-point filler as a horizontal coordinate; then, the image is subjected to section-by-section derivation, and the slope change value shows that when the concentration is less than 0.01mol/L, the release days exceed 20 days, the slope value is less than-0.001 and is close to zero, and when the slope change value is lower than the concentration limit value, along with the increase of the release days, the release amount of the low-freezing-point filler in the test piece is lower, the snow melting capacity is insufficient, and the service life of melting the ice and snow is prolonged, so that the single release concentration of 0.01mol/L is selected as the lowest working concentration of melting the ice and snow of the test piece;
sixthly, establishing a prediction model of the residual life of the snow melt of the low-freezing-point ultrathin wearing layer:
according to Fick's law in step III, the influence of main factors of temperature correction, load correction and period correction on the apparent diffusion coefficient D (t) of the road when the road actually releases the low-freezing-point filler is corrected by the main factors in the actual road using process, and the correction is shown in a formula (6):
D(t)＝K TIME ×K TEMP ×K LOAD ×D(t 0 ) (6)；
in the formula: k is LOAD Is the load influence coefficient; k TIME The age influence coefficient; k is TEMP Is the temperature coefficient of influence; d (t) 0 ) Is the diffusion coefficient under the standard working condition;
firstly, correcting age influence coefficient K TIME ：
Age coefficient of influence K TIME Correcting by adopting a formula (7);
in the formula: t is exposure time, 1d is taken; t is t 0 The soaking time is; k TIME The age influence coefficient; a is age index, a at 0 ℃ is-1.042, a at 10 ℃ is-0.9906, and a at 20 ℃ is-0.8781;
② correcting the temperature influence coefficient K TEMP ：
Coefficient of influence of temperature K TEMP Correcting by adopting a formula (8);
in the formula: e is the activation energy in the transmission process, and the value of E is 9.33232, kilojoule; r is a gas constant of 8.31451J/mol.K; t is the current temperature and is 293K; t is 0 Reference temperature, 273K respectively;
k is calculated by the formula (8) TEMP When the temperature is increased by 10 ℃, the correction coefficient is enlarged by 1.15 times;
thirdly, correcting the load influence coefficient K LOAD ：
Normally, the load influence coefficient K is corrected LOAD Calculating according to the formula (9);
K LOAD ＝β×σ γ (9)；
in the formula: beta is the correction coefficient of the number of times of the axle load action,
wherein X 1 The cycle number in a single period is ten thousand; d (t) 0 ') the permeability coefficient of the effective components under the actual measurement load condition, and the unit is mol/(L.m.s); sigma γ The stress ratio correction coefficient of the load of the road surface and the damage load of the road surface,
wherein sigma c Is the load stress ratio;
fourthly, the calculation formula of the apparent diffusion coefficient D (t) of the low freezing point filler can be known by combining the formulas (6), (7), (8) and (9) and is shown in the formula (10);
fifth, combining the formulas (4) and (10), the residual concentration C of the low-freezing point filler in the asphalt mixture Marshall test piece formed by the low-freezing point filler Residue of The calculation formula of (2) is shown in formula (11);
seventhly, estimating the service life of the effective components with the low freezing point by combining actual meteorological data:
correcting three factors of age, temperature and load respectively according to a low freezing point filler migration rule, wherein the age influence system reaches an icing number K TIME Referring to the formula (7), the exposure time t is 1d, and the soaking time t 0 Taking 0 deg.C (existing state) at 180d temperature, and-1.042 age index, then K TIME 0.004467; coefficient of influence of temperature K TEMP Calculated using equation (8) where the reference temperature T 0 0 deg.C (273K) and 20 deg.C (293K) for current temperature T TEMP 1.32; correction of the load influence coefficient K LOAD Calculating according to the formula (9), wherein the cyclic load is 30% of ultimate failure load, namely the ratio sigma of the cyclic load to the maximum failure load c Taking 0.3, and taking 15000 times as the cycle number in a single period, X 1 Taking 1.5, D (t) 0 ' diffusion coefficient of 2.13X 10 for the measured load regime - 6 mol/(L.m.s); the axial load frequency correction coefficient beta is 0.217 and the stress ratio correction coefficient sigma is respectively obtained γ 5.737, and finally obtaining a load correction coefficient K through calculation LOAD Taking 1.247;
finally, the formula (11) is adopted, and the diffusion coefficient D (t) under the standard working condition is adopted 0 ) Is 6.2X 10 -6 The thickness of the ultra-thin wearing layer with the low freezing point is 2cm (namely x is 2 cm), and the relation between the residual concentration and the precipitation concentration of the filler with the low freezing point is established;
secondly, taking 0.01mol/L and 0.04mol/L determined in the fourth step and the fifth step as evaluation indexes of the service life range of the Marshall test piece of the asphalt mixture formed by the low freezing point filler; the mass fraction of the low-freezing-point filler in the test piece is 3.8%; soaking the formed asphalt mixture Marshall test piece into 0.5L of water to release, wherein the residual concentration of the low freezing point filler is lower than 0.01mol/L after 20 days, and therefore, 20d is taken as a laboratory life index;
thirdly, combining meteorological data to predict the actual service life:
combining the laboratory life index with meteorological data information to carry out on-site actual conversion, and carrying out equal-scale conversion on the water addition index and the actual environment precipitation index in the experimental process so as to calculate the actual life index of the ultra-thin wearing layer formed by the low freezing point filler, wherein the formula (12) is shown;
in the formula: d is the estimated life, and the unit is d; l is 1 Adding 500mL of water for laboratory actual measurement, wherein the unit is mL for 20 days; l is a radical of an alcohol 2 As a weather numberAccording to the converted average annual precipitation amount,
d is the area of the road surface, and the actual water immersion area of the test piece is taken to be 90 mm;
is 63.62cm 2 (ii) a L is the annual average rainfall, and the average value is 500 mm.
2. The method for estimating the residual life of the snow melt of the low-freezing-point ultrathin wearing layer based on the snow melt performance as claimed in claim 1, wherein the low-freezing-point filler is an anti-ice snow melt low-freezing-point filler ZG-F-I.
3. The method for estimating the residual life of the snow melt on the basis of the snow melt performance of the low-freezing-point ultrathin wearing layer as claimed in claim 1, wherein in the first step, m is 1200 g; in the first step, L is 0.5L.
4. The method according to claim 1, wherein the concentration of the low-freezing-point filler solution in the second step is 0.05mol/L, 0.1mol/L, 0.15mol/L, 0.2mol/L, 0.25mol/L, 0.3mol/L, 0.35mol/L and 0.4mol/L, respectively.
5. The method for estimating the residual life of the snow melt of the low-freezing-point ultrathin wearing layer based on the snow melt performance as claimed in claim 1, wherein the concentrations of the low-freezing-point filler solution in the fourth step are respectively 0mol/L, 0.01mol/L, 0.02mol/L, 0.03mol/L, 0.04mol/L, 0.05mol/L, 0.06mol/L, 0.07mol/L, 0.08mol/L, 0.09mol/L and 0.1 mol/L.
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