Method for determining component content of high-rubber-content polyurethane mixture

Abstract

The invention relates to the technical field of road engineering, in particular to a method for determining the content of each component of a high-rubber-content polyurethane mixture, which comprises the following steps: heating and melting the high-rubber-content polyurethane mixture at a temperature lower than the melting point of rubber; mixing and dissolving the heated and molten mixture with an organic solvent, and filtering after dissolving polyurethane; heating and drying the filtered aggregate, and weighing the mass; standing the dried aggregate in a solvent to separate the waste rubber particles in the filtered aggregate from the stone; respectively sieving the waste rubber particles and the stones, weighing the mass and calculating; the density of the solvent is larger than that of the waste rubber particles and smaller than that of the stones. The method for determining the content of each component designed by the invention can accurately determine the content of each component of the high-rubber-content polyurethane mixture, and provides a detection means for construction quality control.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering, and particularly to a method for determining the content of each component of a polyurethane mixture with a high rubber content. Background Art

[0002] The polyurethane mixture is prepared by mixing polyurethane adhesive, graded aggregates, and waste tire rubber particles in a certain proportion. The presence of a high content of waste rubber forms a mixture structure with large voids, endowing it with excellent porous sound absorption / elastic vibration damping coupling noise reduction ability, far exceeding the existing low-noise road surface technology level, which can greatly improve the travel experience of drivers and passengers and reduce the impact of traffic noise on residents along the line. However, the existing polyurethane mixture is still mixed using an asphalt mixing plant. The polyurethane adhesive and rubber particles need external equipment and are integratedly controlled in the control room, and the accuracy of feeding is more uncertain than that of asphalt mixture. Therefore, accurately verifying the feeding accuracy and the actual production mix ratio is crucial for ensuring the performance of the polyurethane mixture and subsequent optimization of the construction process.

[0003] At present, there are many limitations in applying the conventional mixture mix ratio verification method to polyurethane mixtures. For example, the traditional combustion method will cause the complete combustion of polyurethane and waste rubber at high temperatures, and it is impossible to accurately separate each component; the centrifugal separation method is difficult to effectively separate the bonded polyurethane and rubber particles; although the solvent extraction method can separate some components, it is difficult to completely separate polyurethane and rubber. The inapplicability of these methods makes it difficult to accurately verify the actual production mix ratio of polyurethane mixtures, affecting quality control and performance optimization. In addition, the existing verification methods often take a long time and are costly, and it is difficult to meet the requirements of rapid construction and timely adjustment. Therefore, a verification calculation method for the feeding accuracy and actual production mix ratio of polyurethane mixtures is needed. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for determining the content of components of a polyurethane mixture with a high rubber content. By utilizing the difference in the melting and decomposition temperatures of waste rubber and polyurethane, and ensuring that the waste rubber does not undergo a decomposition reaction when the cementing material is fully melted, and combining the property that polyurethane is soluble in acetamide solvent, the grading composition ratio of the actual mixed aggregates on site is determined through melting and dissolution tests, which can well solve the problem in the prior art that it is difficult to accurately verify the actual production mix ratio of polyurethane mixtures.

[0005] In the first aspect, the method for determining the content of components of a polyurethane mixture with a high rubber content provided by the present invention includes: 1) Heating and melting the polyurethane mixture at a temperature lower than the melting point of rubber.

[0006] 2) Mixing and dissolving the heated and melted mixture with an organic solvent, and filtering after the polyurethane is dissolved.

[0007] 3) Heat the filtered aggregate and then dry it and weigh it.

[0008] 4) Let the dried aggregate stand in a solvent to separate the waste rubber particles in the filtered aggregate from the stone; sieve, weigh and calculate the waste rubber particles and the stone respectively; the density of the solvent is greater than the density of the waste rubber particles and less than the density of the stone.

[0009] Preferably, in step 1), the temperature of the heating and melting is not lower than 180 °C and not higher than 250 °C, preferably 200 - 240 °C.

[0010] More preferably, the heating time of the heating and melting is 5 - 10 min, preferably to completely melt the polyurethane and prevent the waste rubber from decomposing.

[0011] More preferably, in step 2), the organic solvent is a solvent that can dissolve polyurethane, is not easy to produce toxic substances and is not easy to explode, preferably an acetamide solution, more preferably an N,N - dimethylacetamide solution.

[0012] Preferably, the molten polyurethane mixture is put into an acetamide solution. After the molten polyurethane adhesive is dissolved, observe that the solvent changes from transparent to dark yellow, and collect the solvent and the sieved aggregate. In the dissolving step of the present invention, after the solution color changes from transparent to dark yellow, the subsequent steps are carried out.

[0013] Preferably, in step 3), the temperature of the heating and drying is not higher than 100 °C, preferably 70 - 80 °C; and / or the heating time of the heating and drying is 5 - 10 min, and the sum of the masses of the waste rubber and the stone is m b .

[0014] Preferably, in step 4), the dried aggregate is mixed with the solvent and allowed to stand for 30 ± 5 min, and the waste rubber particles suspended on the surface of the solvent and the stone sinking to the bottom of the solvent are collected; wherein, the density of the solvent is greater than the density of the waste rubber particles and lower than the density of the stone, and the solvent is preferably glycerol.

[0015] More preferably, in step 4), it further includes sieving after mixing the waste rubber particles with water; and / or sieving after mixing the stone with water, weighing respectively and calculating the percentage of retained mass, cumulative percentage of retained mass and mass passing rate of the stone.

[0016] More preferably, in step 4), the waste rubber particles are mixed with water and sieved through filter sieves with apertures of 2.36 mm and 1.18 mm, the waste rubber particles of different particle sizes passing through the sieve are collected and heated and dried at a temperature of 100 ± 5 °C, and the masses of the waste rubber particles of each particle size are weighed.

[0017] More preferably, in step 4), the stone material and water are mixed and passed through a filtering sieve with pore diameters of 0.075 mm, 0.15 mm, 0.3 mm, 0.6 mm, 1.18 mm, 2.36 mm, 4.75 mm, 9.5 mm, and 13.2 mm. The sieved stone materials with different particle sizes are collected and heated and dried at a temperature of 100 ± 5 °C, and the masses of the stone materials with each particle size are weighed.

[0018] More preferably, step 4) further includes: calculating the dosage of the polyurethane adhesive; the dosage of the polyurethane adhesive is calculated according to the following formula: m a =m - m b Formula 1 In the formula, m a is the dosage of the polyurethane adhesive, m is the polyurethane mixture, and m b is the sum of the masses of the waste rubber particles and the stone material.

[0019] More preferably, step 4) further includes: in the order from the largest to the smallest sieve pore diameter, they are 13.2 mm, 9.5 mm, 4.75 mm, 2.36 mm, 1.18 mm, 0.6 mm, 0.3 mm, 0.15 mm, and 0.75 mm; preferably, the cumulative sieve residue of each grade is calculated according to the following formula: In the formula, a i is the percentage of the cumulative sieve residue of the i-th sieve pore, m i is the mass of the material remaining on the i-th sieve pore, and m b is the total mass of the stone material and the waste rubber particles.

[0020] Preferably, the cumulative sieve residue is calculated according to the following formula: In the formula, A i represents the cumulative sieve residue percentage of the i-th sieve pore, and a i is the percentage of the cumulative sieve residue of the i-th sieve pore; preferably, by calculating the percentage of the cumulative sieve residue A i , the mass passing rate of each grade of the aggregate is calculated, and the actual production mix ratio of the polyurethane mixture is obtained.

[0021] Preferably, the mass passing rate is calculated according to the following formula: In the formula, P i represents the mass passing rate of the i-th sieve pore, and A i represents the cumulative sieve residue percentage of the i-th sieve pore.

[0022] Further preferably, the content of waste rubber in the polyurethane mixture is not less than 10%. According to specific embodiments of the present invention, the polyurethane mixture is a high rubber content polyurethane mixture, and the content of waste rubber in the polyurethane mixture is not less than 10%.

[0023] The method for determining the component content of the polyurethane mixture provided by the present invention takes the pavement core sample or the Marshall specimen formed in the laboratory as the research object. Through steps such as heating, dissolving, separating, filtering, and evaporating, by utilizing the difference in the melting and decomposition temperatures of waste rubber and polyurethane and the difference in the densities of waste rubber and stone materials, and combining with the property that polyurethane is soluble in acetamide solvent, the composition ratio of each component of the mixture is determined through melting and dissolution tests. In particular, the specific process and parameters are optimized to achieve more accurate separation and quantitative analysis of each component of the polyurethane mixture composed of polyurethane adhesive, waste rubber particles, and mineral materials, thereby more accurately verifying the mix ratio and ensuring the performance of the mixture and the quality of the road surface.

[0024] In the second aspect, the present invention provides the application of the method for determining the component content of the above-mentioned high rubber content polyurethane mixture, especially in the verification and calculation of the component content of the high rubber content polyurethane mixture in the pavement core sample, the Marshall specimen formed in the laboratory, and / or the high rubber content polyurethane mixture mixed in the asphalt mixing plant. The method provided by the present invention heats and melts the polyurethane mixture at a temperature below the melting point of rubber, mixes and dissolves the heated and melted mixture with an organic solvent to obtain a dissolved mixture liquid, separates, filters, and evaporates the dissolved mixture liquid, and then weighs and calculates. It is applicable to the analysis of pavement core samples and Marshall specimens that have been formed in the laboratory. By processing and analyzing the samples, accurate verification of the component content of the high rubber content polyurethane mixture is achieved.

[0025] The beneficial effects of the present invention are at least as follows: The method for determining the component content of the high rubber content polyurethane mixture provided by the present invention realizes the effective separation and precise quantification of the mixture components by combining solvent dissolution and melting tests and utilizing the melting temperature difference between polyurethane and waste rubber. This method operates below 500°C, avoiding the complete combustion of polyurethane and rubber caused by high temperature, thus overcoming the limitations of the traditional combustion method in verifying the mix ratio of the mixture. Through steps such as temperature-controlled heating, selective solvent dissolution, multi-stage screening, fine filtration, and weighing calculation, this method can gradually separate each component of the mixture and finally obtain the accurate component ratio. This innovative method significantly improves the accuracy and reliability of verifying the actual production mix ratio of the high rubber content mixture, providing a more effective solution for material proportioning in road engineering. Description of the Drawings

[0026] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is a flowchart for determining the content of each component of the high rubber content polyurethane mixture provided by the embodiment of the present invention.

[0028] Figure 2 It is a diagram of the cored sample of the mixture provided by the embodiment of the present invention.

[0029] Figure 3 It is a diagram of the heating and melting of the mixture provided by the embodiment of the present invention.

[0030] Figure 4 It is a diagram of the dissolution of the mixture in the acetamide organic solvent provided by the embodiment of the present invention.

[0031] Figure 5 It is a color comparison diagram of the acetamide organic solvent before and after dissolving the polyurethane adhesive provided by the embodiment of the present invention.

[0032] Figure 6 It is an aggregate composition diagram of the mixture after completely separating the polyurethane adhesive provided by the embodiment of the present invention.

[0033] Figure 7 It is a separation diagram of waste rubber particles and stones provided by the embodiment of the present invention. Detailed implementation manners

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0035] In the ranges disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0036] For those without specific technologies or conditions indicated in the embodiments, they shall be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications. For those instruments and the like without the manufacturer indicated, they are all conventional products that can be obtained through regular channels. The methods are all conventional methods unless otherwise specified, and the raw materials can all be obtained from public commercial channels unless otherwise specified. For those without specific technologies or conditions indicated in the embodiments, they shall be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications.

[0037] In some embodiments of the present invention, the method for determining the component content of the high rubber content polyurethane mixture includes: 1) Heating and melting the polyurethane mixture at a temperature below the melting point of the rubber.

[0038] 2) Mixing and dissolving the heated and melted mixture with an organic solvent, and filtering after the polyurethane is dissolved.

[0039] 3) Heating, drying and weighing the filtered aggregate.

[0040] 4) Standing the dried aggregate in the solvent to separate the waste rubber particles in the filtered aggregate from the stone; sieving, weighing and calculating the waste rubber particles and the stone respectively; the density of the solvent is greater than the density of the waste rubber particles and less than the density of the stone. The method for determining the content of each component designed in the embodiments of the present invention can accurately determine the content of each component of the high rubber content polyurethane mixture and ensure the performance of the mixture and the pavement quality. The present invention combines the solvent dissolution and melting tests, utilizes the melting temperature difference between polyurethane and waste rubber and the density difference between waste rubber and stone, and separates and calculates the proportion of each component through specific steps such as heating, dissolving, separating, filtering and evaporation, effectively solving the problems that the actual production mix ratio of the high rubber content pavement cannot be calculated and the verification accuracy is insufficient.

[0041] The method provided by the embodiments of the present invention is applicable to the high rubber content polyurethane mixture, and realizes effective separation and accurate calculation by utilizing the differences in the physical and chemical properties of the two materials. This method is carried out below 500 °C, avoiding the problem of complete combustion of polyurethane and waste rubber at high temperatures, and overcoming the inaccuracy and limitations of the traditional combustion method in verifying the mix ratio of such mixtures. The present invention combines the solvent dissolution and melting tests, utilizes the melting temperature difference between polyurethane and waste rubber, and realizes the gradual separation of the mixture components through multiple steps such as heating, dissolving, separating, filtering and evaporation, and finally obtains the accurate proportion of each component aggregate through weighing and calculation. This method combines the characteristics of the solvent dissolution method and the melting method, and realizes the accurate separation and quantitative analysis of the mixture components through selective solvent dissolution and temperature control.

[0042] As a preferred embodiment, in step 1), the temperature of the heating and melting is not lower than 180°C and not higher than 250°C, preferably 200 - 240°C, such as 200, 205, 210, 215, 220, 225, 230, 235°C, etc. and any values and ranges therebetween. In the present invention, the melting temperature of the polyurethane is not lower than 180°C, and the initial melting temperature of the waste rubber is 250°C. Preferably, the mixture is melted and decomposed at a temperature in the range of 200 - 240°C. Conducting a melting test at the preferred melting temperature can better ensure that the physical state of the rubber particles is not damaged while ensuring the difference in the melting and decomposition temperatures of the waste rubber and the polyurethane, and melt and disperse the mixture.

[0043] In a further preferred embodiment, the heating time of the heating and melting is 5 - 10 min, preferably used to completely melt the polyurethane without decomposition of the waste rubber. For example, the heating time is 5, 6, 6.5, 7, 7.5, 8, 9, 10 min, etc. and any values and ranges therebetween. By controlling the heating time, it is ensured that the polyurethane is fully melted without affecting the physical state of the waste rubber, thereby achieving the preliminary separation of the two materials.

[0044] In the embodiment of the present invention, with reference to the on-site production mix ratio of the polyurethane mixture, by utilizing the difference in the melting and decomposition temperatures of the waste rubber and the polyurethane, and combining the property that the polyurethane is soluble in acetamide solvent, the gradation composition ratio of the actual on-site mixed ore is determined through melting and dissolution tests, and then compared with the designed mix ratio; the melting temperature of the polyurethane is not lower than 180°C, and the initial melting temperature of the waste rubber is 250°C. The mixture is melted and decomposed at a temperature in the range of 200 - 240°C for 5 - 10 min. By using the melting point difference and dissolution properties of the two materials, the polyurethane adhesive is separated, and the rubber particles and stones are retained. Especially under the preferred conditions, at a specific heating temperature and heating time, the polyurethane can be completely melted while the waste rubber does not decompose. The method for determining the component content of the high rubber content polyurethane mixture designed by the present invention effectively solves the problem that the actual production mix ratio of the polyurethane pavement cannot be calculated or the verification accuracy is insufficient.

[0045] In a further preferred embodiment, in step 2), the organic solvent is a solvent that can dissolve polyurethane, is not prone to generating toxic substances, and is not explosive, preferably an acetamide solution, more preferably an N,N-dimethylacetamide solution. In the present invention, compared with other solvents, the preferred N,N-dimethylacetamide solvent can not only better dissolve the melted polyurethane adhesive, but also is not prone to generating toxic substances and is not explosive, and has better comprehensive effects.

[0046] In a preferred embodiment, the molten polyurethane mixture is put into an acetamide solution. After the molten polyurethane adhesive is dissolved and the solvent changes from transparent to dark yellow, the solvent and the sieved aggregates are collected. In the dissolution step of the present invention, the subsequent steps are carried out after the solution color changes from transparent to dark yellow. In the present invention, the criterion for judging whether the polyurethane is completely dissolved is that the solution color changes from transparent to dark yellow to ensure the integrity of the dissolution process.

[0047] In a preferred embodiment, in step 3), the temperature of the heating and drying is not higher than 100 °C, preferably 70 - 80 °C; and / or, the heating time of the heating and drying is 5 - 10 min, and the sum of the masses of the waste rubber and the stone is m b .

[0048] As a preferred embodiment, in step 4), the dried aggregates are mixed with the solvent and left standing for 30 ± 5 min, and the waste rubber particles suspended on the surface of the solvent and the stones sinking to the bottom of the solvent are collected; wherein, the density of the solvent is greater than the density of the waste rubber particles and lower than the density of the stones, and the solvent is preferably glycerol. Compared with other solvents, the selected specific solvent glycerol has the best effect.

[0049] In a further preferred embodiment, in step 4), it further includes sieving after mixing the waste rubber particles with water; and / or sieving after mixing the stones with water, weighing them respectively and calculating the individual sieve residue, cumulative sieve residue and mass passing rate of the stones.

[0050] In a further preferred embodiment, in step 4), the waste rubber particles are mixed with water and sieved through filter sieves with pore sizes of 2.36 mm and 1.18 mm, and the waste rubber particles of different particle sizes passing through the sieve are collected and heated and dried at a temperature of 100 ± 5 °C, and the masses of the waste rubber particles of each particle size are weighed.

[0051] In a further preferred embodiment, in step 4), the stones are mixed with water and sieved through filter sieves with pore sizes of 0.075 mm, 0.15 mm, 0.3 mm, 0.6 mm, 1.18 mm, 2.36 mm, 4.75 mm, 9.5 mm, 13.2 mm, and the stones of different particle sizes passing through the sieve are collected and heated and dried at a temperature of 100 ± 5 °C, and the masses of the stones of each particle size are weighed.

[0052] In the embodiment of the present invention, the evaporation solvent temperature is preferably 100 °C, which can effectively evaporate solvents such as acetamide without affecting other components and ensure the accuracy of the final weighing result.

[0053] In the embodiment of the present invention, the gradual separation of the components of the mixture is achieved through multiple steps such as heating, dissolution, separation, filtration and evaporation, and finally the precise ratio of each component aggregate is obtained through weighing and calculation.

[0054] In the embodiments of the present invention, step 4) further includes: calculating the dosage of the polyurethane adhesive; the dosage of the polyurethane adhesive is calculated according to the following formula: m a =m - m b Formula 1 In the formula, m a is the dosage of the polyurethane adhesive, m is the polyurethane mixture, and m b is the sum of the masses of the waste rubber particles and the stone.

[0055] In the embodiments of the present invention, step 4) further includes: in the order from the largest to the smallest sieve hole diameters, which are 13.2 mm, 9.5 mm, 4.75 mm, 2.36 mm, 1.18 mm, 0.6 mm, 0.3 mm, 0.15 mm, 0.75 mm (setting the mass of each single grade to be m 1 、m 2 、m 3 、m 4 、m 5 、m 6 、m 7 、m 8 、m 9 ); preferably, the cumulative sieve residue of each grade is calculated according to the following formula: In the formula, a i is the cumulative sieve residue percentage of the i-th sieve hole, m i is the mass of the material remaining on the i-th sieve hole, and m b is the total mass of the stone and the waste rubber particles.

[0056] In the embodiments of the present invention, the cumulative sieve residue is calculated according to the following formula: In the formula, A i represents the cumulative sieve residue percentage of the i-th sieve hole, and a i is the cumulative sieve residue percentage of the i-th sieve hole; preferably, by calculating the cumulative sieve residue percentage A i , the mass passing rate of each grade of the aggregate is calculated, and the actual production mix ratio of the polyurethane mixture is obtained.

[0057] In the embodiments of the present invention, the mass passing rate is calculated according to the following formula: In the formula, P i represents the mass passing rate of the i-th sieve hole, and A iTo represent the cumulative sieve residue percentage of the i-th sieve hole. In the present invention, on the basis of optimizing the process and its conditions, each calculation formula is also improved. Through the overall optimization design of the scheme, technical obstacles can be well overcome, and the content of each component of the polyurethane mixture with a high rubber content can be well determined.

[0058] In an embodiment of the present invention, the content of waste rubber in the polyurethane mixture is not less than 10%. According to a specific embodiment of the present invention, the polyurethane mixture is a polyurethane mixture with a high rubber content, and the content of waste rubber in the polyurethane mixture is not less than 10%, preferably 13% - 60% (by weight percentage), such as 13%, 15%, 18%, 25%, 30%, 45%, 60%, etc. and any value therebetween. The embodiment of the present invention provides a method for determining the content of each component of the polyurethane mixture, taking the core sample drilled from the road surface or the Marshall specimen formed in the laboratory as the research object. Through steps such as heating, dissolving, separating, filtering, and evaporating, by using the difference in the melting and decomposition temperatures of waste rubber and polyurethane and the difference in the densities of waste rubber and stone, and combining the property that polyurethane is soluble in acetamide solvent, the composition ratio of each component of the mixture is determined through melting and dissolution tests. Especially by optimizing the specific process and parameters, more accurate separation and quantitative analysis of each component of the polyurethane mixture composed of polyurethane adhesive, waste rubber particles, and mineral materials are realized, so as to more accurately verify the mix ratio and ensure the performance of the mixture and the quality of the road surface.

[0059] In a preferred embodiment of the present invention, the method for determining the content of components of the polyurethane mixture with a high rubber content includes the following steps: 1) Weigh the core sample drilled from the road surface or the Marshall specimen formed in the laboratory as m, and heat it at a temperature of 200 - 240 °C for 5 - 10 min to obtain the molten polyurethane mixture; until all the polyurethane adhesive is melted and the mixture presents a dispersed state.

[0060] 2) Mix and dissolve the molten polyurethane mixture with an acetamide solution. After all the molten polyurethane adhesive is dissolved, observe that the solvent changes from transparent to dark yellow, and collect the sieved aggregate.

[0061] 3) Put the sieved aggregate into an oven at 70 - 80 o °C and heat for 5 - 10 min, then weigh the mass as m b .

[0062] 4) Let the dried aggregate stand in glycerol solvent for 30 min, and collect the waste rubber particles suspended on the surface of the solvent and the stone sinking to the bottom of the solvent.

[0063] 5) Dry the waste rubber particles and the stone sinking to the bottom of the solvent collected in step four at 100 o °C.

[0064] 6) Place the waste rubber particles in an aqueous solution and pass them through sieve meshes with pore sizes of 2.36 mm and 1.18 mm, and collect the sieved waste rubber particles with different particle sizes.

[0065] 7) Heat the sieved waste rubber particles with different particle sizes in step 5 in a heating furnace at 100 ± 5 °C until all the water solvent remaining on the surface of the stone material has evaporated, and then weigh the mass of the waste rubber materials with different particle sizes.

[0066] 8) Calculate the dosage of the polyurethane adhesive for the pavement core sample or the Marshall sample formed in the laboratory as m a =m - m b .

[0067] 9) Place the weighed stone materials in step 4 in an aqueous solution and pass them through sieve meshes with pore sizes of 0.075 mm, 0.15 mm, 0.3 mm, 0.6 mm, 1.18 mm, 2.36 mm, 4.75 mm, 9.5 mm, and 13.2 mm, and collect the filtrate and the sieved stone materials with different particle sizes.

[0068] 10) Heat the collected sieved stone materials with different particle sizes in a heating furnace at 100 ± 5 °C until all the water solvent remaining on the surface of the stone material has evaporated, weigh the mass of the stone materials with different particle sizes, add them to the mass of the waste rubber with different particle sizes, and calculate the cumulative percentage retained, the cumulative percentage passing, and the percentage passing by mass of the stone materials.

[0069] Example 1 This example provides a method for determining the component content of a polyurethane mixture with a high rubber content. The method provided in this example is described below in combination with Figures 1-7 Describe the method provided in this example.

[0070] In this example, the target void ratio of the mixture is set to 24%, the coarse aggregate is basalt stone material, the fine aggregate is limestone stone material, and the binder is a moisture-curing one-component polyurethane adhesive. Three different gradations are designed within the gradation range, and the mineral aggregate gradation is preferably determined through tests as shown in Table 1, where the addition amount of mineral powder is 3% and the proportion of the polyurethane adhesive is 4.5%.

[0071] Table 1 Mineral aggregate gradation

[0072] Set the target rubber particle content of the mixture to 15%. Based on the equal-volume replacement method, use rubber particles with particle sizes of 1.18 mm and 2.36 mm to partially replace the stone materials with the same particle sizes, and the replacement contents for each gear are 5% and 10% respectively.

[0073] Through the scattering and bleeding tests, the dosage range of the binder polyurethane in the polyurethane mixture was determined to be 4.42% - 4.51% (calculated based on the total mass of mineral aggregates before replacing rubber particles) according to the inflection points of the two curves, and the appropriate dosage of polyurethane was finally determined to be 4.5%.

[0074] Based on the above mixture ratio design parameters of the mixture, a polyurethane pavement was laid, and core samples were taken after the pavement was built for a period of time. The actual production mixture ratio parameters of each component of the mixture were calculated by using a method for determining the component content of a high rubber content polyurethane mixture provided by the present invention, and compared with the designed mixture ratio, providing a reference for exploring the influence of the mixture ratio parameters of each component on its noise reduction / road performance, and also providing a theoretical basis for subsequent optimization of the construction process. The method for determining the component content of the high rubber content polyurethane mixture provided in the embodiment of the present invention ( Figure 1 ), the specific steps are as follows: (1) After weighing the mass m of the pavement core sample ( Figure 2 ), it was placed in an oven, and the oven temperature was set at 220 °C and heated for 7 min to ensure that all the polyurethane adhesives were melted and the mixture showed a dispersed state.

[0075] In step (1), mainly through the difference in the melting and decomposition temperatures of waste rubber and polyurethane, it is ensured that without damaging the physical state of the waste rubber, the polyurethane adhesive is melted into a flowing state, laying a foundation for the complete dissolution of the polyurethane adhesive in the organic solvent in step (2). Among them, the melting temperature of polyurethane is lower than 200 °C, and the initial melting temperature of waste rubber is 300 °C. The mixture is heated in the temperature range of 200 - 240 °C to make the mixture in a completely dispersed and loose state, and it is more conducive to subsequent operations. The melting process of the polyurethane mixture is shown in Figure 3 .

[0076] (2) The molten and loose polyurethane mixture was immediately put into acetamide organic solvent. After all the polyurethane adhesives were dissolved, it was observed that the solvent changed from transparent to dark yellow (the result is as shown in Figures 4-5 ), and the aggregate waste rubber and stone ( Figures 6-7 ) were collected.

[0077] (3) The collected aggregate waste rubber and stone were heated in an oven at 75 o °C for 7 min and then weighed as m b . The dried aggregate was put into glycerol solvent and left standing for 30 min, and the waste rubber particles suspended on the surface of the solvent and the stone sinking to the bottom of the solvent were collected.

[0078] (4) The waste rubber particles and the stone sinking to the bottom of the solvent collected in step three were dried at 100 o °C respectively.

[0079] (5) Place the waste rubber particles in an aqueous solution and pass them through sieve meshes with pore sizes of 2.36 mm and 1.18 mm, and collect the sieved waste rubber particles with different particle sizes.

[0080] (6) Place the sieved waste rubber particles with different particle sizes from step four in a heating furnace at 100 °C for heating. After all the water solvents remaining on the surface of the stone materials have evaporated, weigh the mass of the waste rubber materials with each particle size.

[0081] (7) Calculate the dosage of the polyurethane adhesive for the pavement core drilling specimen or the Marshall specimen formed in the laboratory as m a = m - m b .

[0082] (8) Place the weighed stone materials m b in an aqueous solution and pass them through sieve meshes with pore sizes of 0.075 mm, 0.15 mm, 0.3 mm, 0.6 mm, 1.18 mm, 2.36 mm, 4.75 mm, 9.5 mm, and 13.2 mm, and collect the filtrate and the sieved stone materials with different particle sizes.

[0083] (9) Place the collected sieved stone materials with different particle sizes in a heating furnace at 100 °C for heating. After all the water solvents remaining on the surface of the stone materials have evaporated, weigh the mass of the stone materials with each particle size, add it to the mass of the waste rubber with each particle size, and calculate the cumulative sieve residue, cumulative sieve retention, and mass passing rate of the stone materials.

[0084] Take a pavement core drilling specimen of 636.5 g. After operating according to the above four steps, the remaining aggregate mass on each engineering sieve hole and the dosage of each component are shown in Tables 2 and 3.

[0085] Table 2 Aggregate weights of sieve holes with different particle sizes

[0086] Table 3 Dosages of each component

[0087] Calculate the cumulative sieve residue results of the aggregate with different particle size sieve holes according to Equation 1 above, and the calculation results are shown in Table 4.

[0088] Table 4 Cumulative sieve residue results of aggregate with different particle size sieve holes

[0089] Calculate the cumulative sieve retention results of the aggregate with different particle size sieve holes according to Equation 2 above, and the calculation results are shown in Table 5.

[0090] Table 5 Cumulative sieve retention results of aggregate with different particle size sieve holes

[0091] Based on the cumulative sieve residue results of aggregates with different particle sizes in Table 5, combined with Equation 3, calculate the mass passing rate of aggregates with different particle sizes, and then determine the mixture ratio. The calculation results are shown in Table 6.

[0092] Table 6 Actual production mixture ratio of polyurethane pavement

[0093] Mutually verify the results obtained by the above polyurethane mixture ratio calculation and verification method with the mixture ratio parameters to test the accuracy of the calculation results of this method, as shown in Tables 7 - 8.

[0094] Table 7 Comparative analysis results of the dosages and mixture ratios of each component of the pavement

[0095] Table 8 Comparative analysis results of the designed and actual production mixture ratios of polyurethane pavement

[0096] Example 2 Adopt the method of Example 1, the difference is that in step (1), the oven temperature is set at 200 °C and heated for 10 min to ensure that all the polyurethane adhesives are melted and the mixture shows a dispersed state.

[0097] Take 701 g of the core sample of the pavement. After operating according to the above four steps, the comparative analysis results of the dosages and mixture ratios of each component of the pavement are shown in Table 9, and the comparative analysis results of the designed and actual production mixture ratios of polyurethane pavement are shown in Table 10.

[0098] Table 9 Comparative analysis results of the dosages and mixture ratios of each component of the pavement

[0099] Table 10 Comparative analysis results of the designed and actual production mixture ratios of polyurethane pavement

[0100] Example 3 Adopt the method of Example 1, the difference is that in step (1), the oven temperature is set at 240 °C and heated for 5 min to ensure that all the polyurethane adhesives are melted and the mixture shows a dispersed state.

[0101] Take 690 g of the core sample of the pavement. After operating according to the above four steps, the comparative analysis results of the dosages and mixture ratios of each component of the pavement are shown in Table 11, and the comparative analysis results of the designed and actual production mixture ratios of polyurethane pavement are shown in Table 12.

[0102] Table 11 Comparative analysis results of the dosages and mixture ratios of each component of the pavement

[0103] Table 12 Comparative Analysis Results of Polyurethane Pavement Design and Actual Production Mix Ratio

[0104] Example 4 The method of Example 1 was adopted, with the difference that in step (1), the oven temperature was set at 180 °C and heated for 5 min, and the mixture showed a dispersed state.

[0105] Take 700 g of the pavement core sample. After operating according to the above four steps, the comparative analysis results of the dosage and mix ratio of each component of the pavement are shown in Table 13, and the comparative analysis results of the polyurethane pavement design and actual production mix ratio are shown in Table 14.

[0106] Table 13 Comparative Analysis Results of the Dosage and Mix Ratio of Each Component of the Pavement

[0107] Table 14 Comparative Analysis Results of Polyurethane Pavement Design and Actual Production Mix Ratio

[0108] Example 4 The method of Example 1 was adopted, with the difference that in step (1), the oven temperature was set at 250 °C and heated for 10 min, and the mixture showed a dispersed state.

[0109] Take 705 g of the pavement core sample. After operating according to the above four steps, the comparative analysis results of the dosage and mix ratio of each component of the pavement are shown in Table 15, and the comparative analysis results of the polyurethane pavement design and actual production mix ratio are shown in Table 16.

[0110] Table 15 Comparative Analysis Results of the Dosage and Mix Ratio of Each Component of the Pavement

[0111] Table 16 Comparative Analysis Results of Polyurethane Pavement Design and Actual Production Mix Ratio

[0112] Combining Examples 1 - 5, the melting temperature and melting time of the molded sample should be within the preferred range. When the temperature is low, the melting time should be extended; when the temperature is high, the melting time should be shortened. When the melting temperature is low and the melting time is short, the polyurethane adhesive is not easily completely melted, and part of it is entangled with the waste rubber, and it cannot be completely dissolved when adding acetamide, resulting in a low content of polyurethane adhesive and a high content of waste rubber. When the melting temperature is high and the melting time is long, the polyurethane adhesive is completely melted, and part of the waste rubber decomposes, resulting in a low content of waste rubber and a relatively large content of 0.075 - 0.3 mm stone materials.

[0113] Comparative Example 1 Take 710 g of road surface core samples. After operating in accordance with the "Test Procedures for Bitumen and Bituminous Mixtures in Highway Engineering" (JTG-E20-T0735-2011), the comparative analysis results of the dosages and mix ratios of each component of the road surface are shown in Table 17, and the comparative analysis results of the road surface design and actual production mix ratios are shown in Table 18.

[0114] Table 17 Comparative Analysis Results of Dosages and Mix Ratios of Each Component of the Road Surface

[0115] Table 18 Comparative Analysis Results of Polyurethane Road Surface Design and Actual Production Mix Ratios

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the content of components of a high rubber content polyurethane mixture, characterized in that: include: 1) Heat and melt the polyurethane mixture at a temperature lower than the melting point of the rubber; 2) Mixing and dissolving the heated and molten mixture with an organic solvent, and filtering the polyurethane after it is dissolved; 3) Heat and dry the filtered aggregate and weigh its mass; 4) The dried aggregate is placed in a solvent to separate the waste rubber particles from the stone in the aggregate; the waste rubber particles and the stone are sieved, weighed and calculated respectively; the density of the solvent is greater than the density of the waste rubber particles and less than the density of the stone.

2. The method for determining the component contents of a high rubber content polyurethane mixture according to claim 1, characterized in that: In step 1), the heating and melting temperature is not less than 180°C and not more than 250°C, preferably 200-240°C; and / or the heating and melting heating time is 5-10 minutes, preferably for completely melting the polyurethane without decomposing the waste rubber.

3. The method for determining the component contents of a high rubber content polyurethane mixture according to claim 2, characterized in that: In step 2), the organic solvent is a solvent that can dissolve polyurethane, is not likely to produce toxic substances, and is not explosive, preferably an acetamide solution, more preferably an N,N-dimethylacetamide solution; Preferably, the heated and molten mixture is placed in an N,N-dimethylacetamide solution, and preferably, after the molten polyurethane adhesive is dissolved and the solvent changes from transparent to dark yellow, the organic solvent and the sieved aggregate are collected.

4. The method for determining the component content of a high rubber content polyurethane mixture according to any one of claims 1 to 3, characterized in that: In step 3), the heating and drying temperature is not higher than 100°C, preferably 70-80°C; and / or the heating time of the heating and drying is 5-10min, and the sum of the mass of the waste rubber and the stone is m b .

5. The method for determining the component contents of a high rubber content polyurethane mixture according to any one of claims 1 to 4, characterized in that: In step 4), the dried aggregate is mixed with a solvent and allowed to stand for 30±5 minutes, and the waste rubber particles suspended on the surface of the solvent and the stones sunk to the bottom of the solvent are collected; wherein the density of the solvent is greater than the density of the waste rubber particles and lower than the density of the stones; and the solvent is preferably glycerol; And / or, step 4) further includes mixing the waste rubber particles with water and then sieving; and / or, mixing the stone with water and then sieving, weighing the mass respectively and calculating the individual sieve residues, cumulative sieve residues and mass pass rate of the stone.

6. The method for determining the component contents of a high rubber content polyurethane mixture according to claim 5, characterized in that: In step 4), the waste rubber particles and water are mixed and passed through filter sieves with apertures of 2.36 mm and 1.18 mm, the sieved waste rubber particles of different particle sizes are collected and heated and dried at a temperature of 100±5° C., and the mass of the waste rubber particles of each particle size is weighed; And / or, the stone and water are mixed and passed through filter sieves with pore sizes of 0.075mm, 0.15mm, 0.3mm, 0.6mm, 1.18mm, 2.36mm, 4.75mm, 9.5mm, and 13.2mm, the sieved stones of different particle sizes are collected and heated and dried at a temperature of 100±5°C, and the mass of stones of each particle size is weighed.

7. The method for determining the component contents of a high rubber content polyurethane mixture according to any one of claims 1 to 6, characterized in that: Step 4) also includes: calculating the amount of polyurethane adhesive; Preferably, the amount of the polyurethane adhesive is calculated according to the following formula: m a =mm b Formula 1 In the formula, m a is the mass of polyurethane adhesive, m is the mass of polyurethane mixture, m b It is the sum of the mass of waste rubber particles and stone.

8. The method for determining the component contents of a high rubber content polyurethane mixture according to any one of claims 1 to 7, characterized in that: Step 4) further includes: in descending order of sieve hole particle size, the sieve holes are 13.2 mm, 9.5 mm, 4.75 mm, 2.36 mm, 1.18 mm, 0.6 mm, 0.3 mm, 0.15 mm, and 0.75 mm; Preferably, the number of mesh holes per level is calculated according to the following formula: In the formula, a i is the percentage of residue in the ith sieve hole, m i is the mass of material remaining on the i-th sieve hole, m b is the total mass of stone and waste rubber particles; Preferably, the cumulative sieve residue is calculated according to the following formula: In the formula, A i is the cumulative percentage of residue in the ith sieve hole, a i is the percentage of the residual screen of the i-th sieve hole; preferably, the percentage of the residual screen A is calculated by i , calculate the mass passing rate of each aggregate level and obtain the actual production mix ratio of the mixture; Preferably, the mass pass rate is calculated according to the following formula: Where P i A is the mass passing rate of the i-th sieve hole. i It represents the cumulative residue percentage of the i-th sieve hole.

9. The method for determining the component contents of a high rubber content polyurethane mixture according to any one of claims 1 to 8, characterized in that: The content of waste rubber in the polyurethane mixture is not less than 10%.

10. Application of the method for determining the content of components of a high rubber content polyurethane mixture according to any one of claims 1 to 9, characterized in that: It is used in the verification calculation of the content of each component of drilled core specimens of mixed pavement, laboratory-molded Marshall specimens and / or high-rubber polyurethane mixtures mixed in asphalt mixing plants.

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