In-situ hot-recycled mixture based on discontinuous blending strategy and its targeted design method

Abstract

The present invention discloses an in-situ hot regeneration mixture based on an intermittent blending strategy and a targeted design method thereof, which belongs to the technical field of in-situ hot regeneration technology. The present invention realizes the targeted proportioning of the regeneration mixture through steps one and two, that is, according to the mineral gradation of the regeneration mixture and the mineral gradation of RAP, the addition amount of minerals of each particle size is targetedly calculated; by adding minerals of corresponding particle sizes with targeted precision, compared with the existing addition of minerals of all particle sizes, the asphalt mixture of the present application will not have the problem of too fine minerals, thereby ensuring the density and durability of the road surface, making the road surface less prone to cracking and fragmentation, improving the bearing capacity and durability of the road surface, and improving the flatness of the road surface; then adjusting the regeneration agent that needs to be added to the regeneration mixture through steps five and six to ensure that the recycled material and the added material can be evenly mixed, thereby ensuring that the regeneration mixture has good high and low temperature stability and water stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of in-situ heat regeneration technology, and in particular relates to an in-situ heat regeneration mixture based on an intermittent blending strategy and a targeted design method thereof. Background Art

[0002] Asphalt pavement maintenance and renovation and expansion construction generate a large amount of waste materials. Recycling these waste materials not only reduces environmental pollution but also reduces material consumption, making it an important and urgent means of achieving sustainable development in road transportation. Asphalt pavement recycling equipment is used to mix a certain proportion of new materials, such as new aggregate, recycled binder, and asphalt regeneration agent, with recycled asphalt mixture materials, inorganic recycled materials, and other asphalt pavement materials to create a recycled mixture. This mixture is then spread and compacted to form the pavement structure layer.

[0003] Existing recycled mixtures generally select a certain proportion of new aggregate and use this material as an additive; because the new aggregate is an asphalt mixture with a determined proportion; the additive contains minerals of all particle sizes, but RAP does not necessarily lose minerals of all particle sizes, and minerals of some particle sizes may not need to be added at all; in this case, using a determined proportion of new aggregate as an additive may cause the synthetic gradation of the recycled round material to be too fine after addition. In order to eliminate this deviation, it is necessary to adjust the asphalt dosage or the mixing ratio of the regeneration agent; this results in a very complicated process of forming the recycled mixture, and also causes the process of forming the recycled mixture to take too long and have low mixing efficiency.

[0004] In summary, the existing design scheme of recycled mixtures has the problems of complicated process and low efficiency. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and provide an in-situ hot recycled mixture based on an intermittent blending strategy and a targeted design method thereof. The design is novel and reasonable, the design time is short, the obtained recycled mixture has a good laying effect, and is easy to promote and use.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A targeted design method for in-situ hot-recycling mixture based on a discontinuous blending strategy includes the following steps:

[0008] Step 1: Obtain recycled asphalt mixture (RAP), conduct indoor tests on the RAP, and determine the asphalt dosage and mineral aggregate gradation of the RAP;

[0009] Step 2: Determine the mineral gradation of the recycled mixture based on the pavement performance requirements and the recycled thickness. Combined with the mineral gradation of RAP, the addition ratio of minerals of different particle sizes is calculated in a targeted manner.

[0010] Step 3: Calculate the amount of asphalt to be added based on the asphalt content of the RAP, the aggregate gradation, and the total asphalt content of the recycled mixture;

[0011] Step 4: Determine the additive according to the calculated asphalt dosage and the addition ratio of each particle size mineral aggregate, and mix the additive with RAP to form a recycled mixture;

[0012] Step 5: Add regeneration agent according to the set regeneration agent mixing ratio, and compare the calculated value of the dynamic viscosity of the regenerated mixture after adding the regeneration agent with the test value to see if they are consistent. If not, increase the regeneration agent mixing ratio according to the set interval and add it again; if so, use the current regeneration agent mixing ratio as the final regeneration agent mixing ratio; the set regeneration agent mixing ratio is expressed by the following formula:

[0013]

[0014] Among them, β is the mixing ratio of regeneration agent, P b is the total asphalt content of the recycled mixture, P nb is the amount of asphalt to be added, K is the percentage, K∈[0%,20%];

[0015] Step 6: Conduct a leakage test on the recycled mixture to obtain the corresponding asphalt loss rate. When the leakage loss rate exceeds the set threshold, reduce the amount of asphalt to be added and repeat step 4: conduct a leakage test on the recycled mixture until the corresponding asphalt loss rate is ≤ the set threshold. Use the corresponding recycled mixture as the final recycled mixture.

[0016] Furthermore, if the added asphalt is modified asphalt, the threshold is set to 0.2, and if the added asphalt is unmodified asphalt, the threshold is set to 0.1.

[0017] Furthermore, in step six, if the amount of asphalt to be added after reduction is less than the set asphalt amount threshold, the amount of asphalt to be added will no longer be reduced, but the amount of coarse material added to the mineral material will be increased and the amount of fine material added to the mineral material will be reduced. The asphalt amount threshold is set in the range of 30% to 40%.

[0018] Furthermore, in step 3, the calculation formula for the amount of asphalt to be added is:

[0019]

[0020] Among them, P nb is the amount of asphalt to be added, P b is the total asphalt content of the recycled mixture, P ob is the asphalt content in RAP, and R is the blending ratio of RAP.

[0021] Furthermore, the test value of the dynamic viscosity of the recycled mixture after adding the regeneration agent is obtained by measuring the viscosity test; the calculated value of the dynamic viscosity of the recycled mixture after adding the regeneration agent is obtained by calculating the following formula:

[0022] lgη mix =(1-α-β)lgη old +(α+β)lgη new

[0023] Among them, η mix is the dynamic viscosity of the regenerated mixture at the first temperature after adding the regeneration agent, η old is the dynamic viscosity of RAP at the first temperature, η new is the dynamic viscosity of the additive at the first temperature after adding the regeneration agent, α is the proportion of added asphalt, and β is the mixing ratio of the regeneration agent;

[0024] The calculation formula for the ratio of added asphalt is as follows:

[0025]

[0026] Among them, P nb is the amount of asphalt to be added, P b is the total asphalt content of the recycled mixture.

[0027] Furthermore, indoor tests employ extraction tests or combustion tests.

[0028] Furthermore, the method also includes: adding a first set amount and a second set amount of asphalt to the final recycled mixture determined in step six, respectively, to form a first recycled mixture and a second recycled mixture respectively; performing Marshall tests on the final recycled mixture, the first recycled mixture, and the second recycled mixture, respectively, and selecting the recycled mixture with the highest stability in the Marshall test as the best recycled mixture; the second set amount is equal to 2 times the first set amount, and the range of the first set amount is 0.1% to 0.3%.

[0029] The present invention also discloses an in-situ hot-regenerated mixture based on a discontinuous blending strategy. The in-situ hot-regenerated mixture is prepared using the above-mentioned targeted design method for in-situ hot-regenerated mixture based on a discontinuous blending strategy.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] The targeted design method of in-situ hot recycled mixture based on the discontinuous blending strategy realizes the targeted proportioning of the recycled mixture through steps one and two, that is, according to the mineral gradation of the recycled mixture and the mineral gradation of RAP, the addition amount of minerals of various particle sizes is targetedly calculated; by adding minerals of corresponding particle sizes with targeted precision, compared with the existing addition of minerals of all particle sizes, the asphalt mixture of the present application will not have the problem of too fine minerals, thereby ensuring the density and durability of the road surface, making the road surface less prone to cracking and fragmentation, improving the bearing capacity and durability of the road surface, and improving the smoothness of the road surface; through step one and two, the targeted design method of in-situ hot recycled mixture based on the discontinuous blending strategy realizes the targeted proportioning of the recycled mixture, that is, according to the mineral gradation of the recycled mixture and the mineral gradation of RAP, the addition amount of minerals of various particle sizes is targetedly calculated; by adding minerals of corresponding particle sizes with targeted precision, compared with the existing addition of minerals of all particle sizes, the asphalt mixture of the present application will not have the problem of too fine minerals, thereby ensuring the density and durability of the road surface, making the road surface less prone to cracking and fragmentation, improving the bearing capacity and durability of the road surface, and improving the smoothness of the road surface; by step two and three Step three calculates the additives for asphalt, and step four realizes the mixing of the recycled material and the additives, which facilitates the calculation and adjustment of the subsequent steps; then steps five and six adjust the regeneration agent that needs to be added to the recycled mixture to ensure that the recycled material and the additives can be evenly mixed; specifically, the calculated value and the test value of the dynamic viscosity of the recycled mixture after adding the regeneration agent are compared to determine the regeneration agent blending ratio, and the amount of regeneration agent and asphalt is adjusted through leakage test to improve the accuracy of the components of the recycled mixture; thereby ensuring that the recycled mixture has good high and low temperature stability and water stability.

[0032] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of a process embodiment of a targeted design method for in-situ hot regeneration mixture based on a discontinuous blending strategy of the present invention;

[0034] Figure 2 Schematic representation of the mineral gradation data of RAP of an embodiment of the targeted design method of in-situ hot regeneration mixture based on the discontinuous blending strategy of the present invention;

[0035] Figure 3 A schematic diagram of a line graph of RAP mineral gradation data of an embodiment of a targeted design method for in-situ hot regeneration mixture based on a discontinuous blending strategy of the present invention;

[0036] Figure 4 Schematic representation of mineral gradation data of recycled mixture in an embodiment of the targeted design method of in-situ hot recycled mixture based on discontinuous blending strategy of the present invention;

[0037] Figure 5 A schematic diagram of a broken line graph of mineral material gradation data of a recycled mixture according to an embodiment of the targeted design method for in-situ hot recycled mixture based on a discontinuous blending strategy of the present invention;

[0038] Figure 6 A schematic diagram of a histogram of three major indicators and dynamic viscosity of a recycled mixture according to an embodiment of the targeted design method for in-situ hot recycled mixture based on a discontinuous blending strategy of the present invention;

[0039] Figure 7 This is a schematic diagram of the gradation data of the additive mineral material according to an embodiment of the targeted design method of the in-situ hot regeneration mixture based on the discontinuous blending strategy of the present invention;

[0040] Figure 8 Schematic representation of synthetic gradation data of recycled mixture according to an embodiment of the method for targeted design of in-situ hot recycled mixture based on discontinuous blending strategy of the present invention;

[0041] Figure 9 Schematic diagram of fatigue life of two recycled mixtures at different strain levels in an embodiment of the targeted design method for in-situ hot recycled mixture based on discontinuous blending strategy of the present invention. DETAILED DESCRIPTION

[0042] Example of a targeted design method for in-situ hot-recycled mixture based on a discontinuous blending strategy:

[0043] like Figure 1-9 As shown in Figure 2, the targeted design method of in-situ hot-recycling mixture based on the discontinuous blending strategy includes the following steps:

[0044] Step 1: Obtain recycled asphalt mixture (RAP), conduct indoor tests on the RAP, and determine the asphalt dosage and mineral gradation of the RAP. The indoor tests are extraction tests or combustion tests.

[0045] Specifically, the RAP is an AC-16 asphalt concrete slab cut from the original road surface of a highway. The corresponding AC-16 asphalt upper layer of the original road surface is subjected to an extraction test according to the JTGE20-2011 test procedure to determine the asphalt content and mineral gradation of the RAP. The asphalt content of the RAP is 4.58%, and the mineral gradation of the RAP is as follows: Figure 2 and Figure 3 shown.

[0046] Depend on Figure 2 and Figure 3 It can be seen that the RAP gradation has exceeded the upper limit of the AC-16 gradation required by the project, and a certain proportion of new mineral aggregate should be added to fine-tune the RAP gradation. Further aggregate testing was conducted on the RAP, and the results of the aggregate test are shown in Table 1. Three major index tests were also conducted on the RAP, and the data for the three major indexes of the RAP are shown in Table 2. These tests observed the current performance of the RAP.

[0047] Table 1

[0048]

[0049] Table 2

[0050]

[0051] Step 2: Determine the mineral gradation of the recycled mixture according to the pavement performance requirements and the recycled thickness, and then combine it with the mineral gradation of RAP to calculate the addition ratio of each particle size of minerals, that is, the mineral gradation of the additive. Optimize and adjust the synthetic gradation of the recycled mixture. The gradation design aims to improve the surface function of the pavement and enhance the anti-skid performance, and to target the supplement of the coarse aggregate lost in the original pavement. Specifically, the mineral gradation of RAP, the mineral gradation of the recycled mixture and the mineral gradation of the additive correspond to the data, such as Figure 4 and Figure 5 As shown. Figure 4 and Figure 5 It can be seen that: without adding the two grades of stone of 0-4mm and 4-7mm in the additives, and only targeted addition of coarse aggregate and mineral powder, the synthetic gradation of the recycled mixture is effectively adjusted, which can achieve the design goal of restoring the anti-skid performance of the road surface. This shows that the RAP gradation itself has replaced part of the fine aggregate. If a continuously graded new material containing a certain proportion of fine aggregate is added, the synthetic gradation of the recycled mixture may be too fine. In the synthetic gradation of the recycled mixture, RAP accounts for 80% and new mineral material accounts for 20%. The new mineral material is composed of 16-22mm, 11-16mm, 7-11mm, and mineral powder, accounting for 2.0%, 13.0%, 3.0%, and 2.0% respectively. According to the conversion of pure new materials, the mineral gradation of the added material is 16-22mm: 11-16mm: 7-11mm: mineral powder = 10%: 65%: 15%: 10%, and it is a discontinuously graded mineral material. The specific mineral gradation is as follows Figure 7 shown.

[0052] Step 3: Calculate the amount of asphalt to be added based on the asphalt content of RAP, aggregate gradation and the total asphalt content of the recycled mixture.

[0053] In step 3, the calculation formula for the amount of asphalt to be added is:

[0054]

[0055] Among them, P nb is the amount of asphalt to be added, P b is the total asphalt content of the recycled mixture, P ob is the asphalt content in RAP, and R is the blending ratio of RAP.

[0056] Based on the characteristics of engineering materials, climate and traffic volume, the total asphalt consumption of AC-16 hot-in-place recycled mixture is estimated to be P b (%) is 4.4%. RAP asphalt content P ob is 4.58%, and the RAP content R is 80%, then the amount of asphalt to be added is P nb It is 0.74%.

[0057] Step 4: Determine the additive according to the calculated amount of asphalt to be added and the addition ratio of mineral aggregates of various particle sizes, and mix the additive with RAP to form a recycled mixture.

[0058] Step 5: Add regeneration agent according to the set regeneration agent mixing ratio, and compare the calculated value of the dynamic viscosity of the regenerated mixture after adding the regeneration agent with the test value to see if they are consistent. If not, increase the regeneration agent mixing ratio according to the set interval and add it again; if so, use the current regeneration agent mixing ratio as the final regeneration agent mixing ratio; the set regeneration agent mixing ratio is expressed by the following formula:

[0059]

[0060] Among them, β is the mixing ratio of regeneration agent, P b is the total asphalt content of the recycled mixture, P nb is the amount of asphalt to be added, K is the percentage, K∈[0%,20%].

[0061] Specifically, the asphalt used as the additive is SBSI-C modified asphalt, and the regeneration agent is HH-X type asphalt regeneration agent.

[0062] Specifically, the test value of the dynamic viscosity of the recycled mixture after adding the regeneration agent is obtained by measuring the viscosity test. The calculated value of the dynamic viscosity of the recycled mixture after adding the regeneration agent is calculated by the following formula:

[0063] lgη mix =(1-α-β)lgη old +(α+β)lgη new

[0064] Among them, η mix is the dynamic viscosity of the regenerated mixture at the first temperature after adding the regeneration agent, η o ld is the dynamic viscosity of RAP at the first temperature, η new is the dynamic viscosity of the additive at the first temperature after adding the regeneration agent, α is the proportion of added asphalt, and β is the mixing ratio of the regeneration agent;

[0065] The calculation formula for the ratio of added asphalt is as follows:

[0066]

[0067] Among them, P nb is the amount of asphalt to be added, P b is the total asphalt content of the recycled mixture.

[0068] In this embodiment, the first temperature is 60°C. The values ​​of K are 0, 0.03, 0.05, and 0.07, and the corresponding values ​​of β are 0.00, 0.02, 0.04, and 0.06. old ,η new and η mix The calculated values ​​are shown in Table 3.

[0069] Table 3

[0070] Parameter value <![CDATA[η o ld test value]]> <![CDATA[η new Test Value]]> <![CDATA[η mix Calculated Value]]> α＝0.17，β＝0 362.5 122.4 301.4 α＝0.17，β＝0.03 362.5 122.4 291.7 α＝0.17，β＝0.05 362.5 106.2 276.7 α＝0.17，β＝0.07 362.5 93.8 262.1

[0071] The experimental and calculated results in Table 5 show that the 60°C dynamic viscosity of the mixed asphalt gradually decreases with increasing regeneration agent content, indicating that the addition of the regeneration agent effectively improves the fluidity of the old asphalt. Specifically, when the regeneration agent content is 0%, the 60°C dynamic viscosity of the regenerated asphalt is 301.4 (Pa·s). However, as the content increases to 3%, 5%, and 7%, the corresponding dynamic viscosities decrease to 291.7 (Pa·s), 276.7 (Pa·s), and 262.1 (Pa·s), respectively. This trend indicates that the addition of the regeneration agent restores the properties of the old asphalt to a certain extent, bringing it closer to the fluidity of the added material, thereby improving the overall performance of the recycled mixture. The regenerated viscosity values ​​of the mixed asphalt are consistently within the range of 260 to 300 Pa·s. The viscosity changes relatively steadily with increasing regeneration agent content, with no sudden or abnormal changes. This indicates that the selected regeneration agent type and content are generally appropriate and can meet the actual project requirements.

[0072] As the proportion of regeneration agent increases, the dynamic viscosity tends to be stable; therefore, there is no need to keep increasing the proportion of regeneration agent. Therefore, the specific value of the regeneration agent proportion is determined by the dynamic viscosity calculation value of the recycled mixture. The three major indicators of the recycled asphalt and the dynamic viscosity at 60℃ after adding asphalt and regeneration agent are measured. The specific measurement data are shown in Table 4 and Figure 6 shown.

[0073] Table 4

[0074]

[0075] In Table 4 and Figure 6In the results, with the increase of the regeneration agent dosage, the performance of the recycled mixture has changed significantly. Specifically, first, as the regeneration agent dosage increases from 0% to 7%, the needle penetration value increases significantly from 28.4 (0.1mm) to 68.4 (0.1mm); the ductility value increases to more than 100cm, and the softening point decreases, but the decrease is not large and remains within a reasonable range. This shows that the addition of the regeneration agent does not significantly weaken the thermal stability of the asphalt, but achieves the regeneration effect by improving its fluidity and low-temperature performance. This shows that the addition of the regeneration agent effectively reduces the viscosity of the asphalt, improves its softness and fluidity, and is beneficial to the construction of the recycled mixture. Secondly, with the increase of the regeneration agent dosage, the 60°C dynamic viscosity gradually decreases, and the 60° viscosity test value of the recycled asphalt when the regeneration agent addition is 5% is different from the calculated value η mix Basically close. That is to say, when the regeneration agent addition amount is 5% (as a percentage of the mass of the old asphalt), the performance of the regenerated asphalt meets the three major indicators and requirements of A-70 asphalt. Therefore, it is preliminarily determined that the regeneration agent addition amount is 5% (as a percentage of the mass of the old asphalt).

[0076] Step 6: Conduct a leakage test on the recycled mixture to obtain the corresponding asphalt loss rate. When the leakage loss rate exceeds the set threshold, reduce the amount of asphalt to be added and repeat step 4: conduct a leakage test on the recycled mixture until the corresponding asphalt loss rate is ≤ the set threshold. Use the corresponding recycled mixture as the final recycled mixture.

[0077] Specifically, if the added asphalt is modified asphalt, the threshold is set to 0.2; if the added asphalt is unmodified asphalt, the threshold is set to 0.1. In this embodiment, the added asphalt is modified asphalt, and the corresponding threshold is set to 0.2. According to step three, the amount of asphalt to be added is 0.74%. Calculating that the added amount accounts for 20% of the recycled mixture, the asphalt content in the recycled mixture is approximately 3.7%. Therefore, leakage tests were conducted based on asphalt content of 3.5%, 3.7%, and 3.9% in the recycled mixture. The specific leakage test results are shown in Table 5.

[0078] Table 5

[0079]

[0080] According to the leakage test results, the asphalt content of the recycled mixture at 3.5% and 3.7% meets the regulatory requirements. Therefore, 3.7% is used as the asphalt content of the recycled asphalt. Furthermore, at 3.7% asphalt content, the degree of asphalt precipitation is still relatively high; therefore, 3.5% is the preferred asphalt content of the recycled mixture.

[0081] To further ensure the performance of the recycled mixture, in step 6, if the amount of asphalt to be added after the reduction is less than the set asphalt dosage threshold, the amount of asphalt to be added is not reduced. Instead, the amount of coarse aggregate added to the aggregate is increased and the amount of fine aggregate added is reduced. The asphalt dosage threshold is set in the range of 30% to 40%. In this embodiment, when adjusting the recycled asphalt in step 6, since the amount of asphalt to be added basically does not need to be adjusted, the step of adjusting the aggregate gradation is not performed. This also shows that the method of discontinuous aggregate gradation makes the preparation of the recycled mixture not only highly precise but also highly efficient.

[0082] To improve the accuracy of the recycled mixture's performance, the method further includes: adding a first set amount and a second set amount of asphalt to the final recycled mixture determined in step 6, respectively, to form a first recycled mixture and a second recycled mixture; performing a Marshall test on the final recycled mixture, the first recycled mixture, and the second recycled mixture, respectively, and selecting the recycled mixture with the highest stability in the Marshall test as the optimal recycled mixture. The second set amount is equal to twice the first set amount, and the first set amount ranges from 0.1% to 0.3%. In this embodiment, the first set amount is 0.2%. The Marshall test was conducted in accordance with the JTG E20-2011 test protocol. The test results are shown in Table 6.

[0083] Table 6

[0084]

[0085] According to the stability data in Table 6, it is not necessary to increase the amount of asphalt. The final recycled mixture in step 6 is the optimal recycled mixture.

[0086] In order to verify the performance of the recycled mixture, the above-obtained recycled mixture was tested. Specifically, the ratio of RAP to additives in the recycled mixture was 1:4. The synthetic gradation of the hot recycled mixture was reviewed according to this additive ratio. The results are shown in Figure 8 By comparison Figure 4 and Figure 8 It can be found that the machine damage results are basically the same.

[0087] A comparative experiment was also conducted to analyze the performance of the recycled mix. The recycled mix synthesized using the discontinuous grading method of this embodiment was designated Type G, while the recycled mix generated using the conventional continuous grading method was designated Type C. The two recycled mixes were tested for high-temperature stability, low-temperature crack resistance, water stability, fatigue performance, and water permeability to analyze and compare their performance differences.

[0088] Type C recycled material is prepared according to the following data: RAP + 5% regeneration agent (calculated as a percentage of the mass of the old asphalt) + 25% continuous AC-16 graded additive (calculated as a percentage of the mass of the old asphalt mixture, the oil-stone ratio is 4.2%, and the mineral aggregate gradation is: 16~22mm: 11~16mm: 7~11mm: 4~7mm: 0~4mm: mineral powder = 10:29:15:11:30:5).

[0089] Type G recycled material is prepared according to the following data: RAP + 5% regeneration agent (calculated as a percentage of the mass of the old asphalt) + 25% additive (calculated as a percentage of the mass of the old asphalt mixture, oil-stone ratio 3.5%, 16-22mm: 11-16mm: 7-11mm: mineral powder = 10:65:15:10).

[0090] The two recycled mixtures were subjected to rutting test, low temperature bending test, immersion Marshall test, freeze-thaw splitting test, water seepage test and fatigue performance test respectively. The test results are shown in Table 7. The fatigue life of the two recycled mixtures at different strain levels is shown in Table 8 and Figure 9 .

[0091] Table 7

[0092] project Type C recycled material G type recycled material Project requirement value Residual stability (%) 92.1 93.6 ＞90 Freeze-thaw splitting strength ratio (%) 88.7 91.2 ＞85 Dynamic stability (times / mm) 7625 8750 ≥5000 <![CDATA[Maximum flexural tensile strain ε B (με)]]> 2855.6 2828.4 ≥2800 Water permeability coefficient (ml / min) 12 36 ≤80

[0093] Table 8

[0094]

[0095] From Table 6, Table 7 and Figure 9 The analysis revealed the following: First, both Type C and Type G recycled materials met or exceeded project requirements across all performance indicators. Specifically, with the exception of the water permeability coefficient, Type G recycled material demonstrated superior performance in high-temperature stability, low-temperature crack resistance, water stability, and fatigue performance. Due to the inclusion of discontinuously graded new materials in Type G recycled material, the gradation of the recycled mixture was optimized, resulting in a reliable dosage of regeneration agent and superior overall performance. Second, Type C recycled material performed better in terms of water permeability coefficient. This indicates that Type C recycled material exhibits superior resistance to water penetration due to the inclusion of a higher amount of fine aggregate in the additives, which helps to seal pores and reduce water infiltration. Finally, in terms of fatigue life, Type G recycled material generally exhibited higher fatigue life than Type C recycled material at various strain levels. This indicates that Type G recycled material exhibits superior fatigue performance under repeated loading. Due to the effective restoration of the dense skeleton structure of Type G recycled material, the long-term stability and durability of the recycled pavement are enhanced.

[0096] Example of in-situ hot-recycled mixture based on discontinuous blending strategy:

[0097] The in-situ hot-recycled mixture based on the discontinuous blending strategy is prepared using the above-mentioned targeted design method for in-situ hot-recycled mixture based on the discontinuous blending strategy. This embodiment is implemented with reference to the above-mentioned embodiment of the targeted design method for in-situ hot-recycled mixture based on the discontinuous blending strategy, which will not be repeated here.

[0098] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A targeted design method for in-situ hot-regeneration mixture based on a discontinuous blending strategy, characterized by: The following steps are included: Step 1: Obtain recycled asphalt mixture (RAP), conduct indoor tests on the RAP, and determine the asphalt dosage and mineral aggregate gradation of the RAP; Step 2: Determine the mineral gradation of the recycled mixture based on the pavement performance requirements and the recycled thickness. Combined with the mineral gradation of RAP, the addition ratio of minerals of different particle sizes is calculated in a targeted manner. Step 3: Calculate the amount of asphalt to be added based on the asphalt content of the RAP, the aggregate gradation, and the total asphalt content of the recycled mixture; Step 4: Determine the additive according to the calculated asphalt dosage and the addition ratio of each particle size mineral aggregate, and mix the additive with RAP to form a recycled mixture; Step 5: Add regeneration agent according to the set regeneration agent mixing ratio, and compare the calculated value of the dynamic viscosity of the regenerated mixture after adding the regeneration agent with the test value to see if they are consistent. If not, increase the regeneration agent mixing ratio according to the set interval and add it again; if so, use the current regeneration agent mixing ratio as the final regeneration agent mixing ratio; the set regeneration agent mixing ratio is expressed by the following formula: in, is the regeneration agent mixing ratio, is the total asphalt content of the recycled mixture, is the amount of asphalt to be added, As a percentage, K ∈[0%,20%]; Step 6: Perform a leakage test on the recycled mixture to obtain the corresponding asphalt loss rate. When the leakage loss rate exceeds the set threshold, reduce the amount of asphalt to be added, repeat step 4, perform a leakage test on the recycled mixture, until the corresponding asphalt loss rate is ≤ the set threshold, and use the corresponding recycled mixture as the final recycled mixture; In step 3, the amount of asphalt to be added is calculated as follows: in, is the amount of asphalt to be added, is the total asphalt content of the recycled mixture, is the asphalt content in RAP, is the blending ratio of RAP; The test value of the dynamic viscosity of the recycled mixture after adding the regeneration agent is obtained by measuring the viscosity test; the calculated value of the dynamic viscosity of the recycled mixture after adding the regeneration agent is obtained by calculating the following formula: in, is the dynamic viscosity of the recycled mixture at the first temperature after adding the regeneration agent, is the dynamic viscosity of RAP at the first temperature, It is the dynamic viscosity of the added material at the first temperature after adding the regeneration agent. The ratio of asphalt added is is the mixing ratio of the regeneration agent; The calculation formula for the ratio of added asphalt is as follows: in, is the amount of asphalt to be added, is the total asphalt content of the recycled mixture.

2. The method for targeted design of in-situ hot-regeneration mixture based on discontinuous blending strategy according to claim 1 is characterized in that: If the added asphalt is modified asphalt, the threshold is set to 0.2; if the added asphalt is unmodified asphalt, the threshold is set to 0.

1.

3. The targeted design method for in-situ hot-regeneration mixture based on the discontinuous blending strategy according to claim 1 is characterized in that: In step six, if the amount of asphalt to be added after reduction is less than the set asphalt amount threshold, the amount of asphalt to be added will no longer be reduced, but the amount of coarse material added to the mineral material will be increased and the amount of fine material added to the mineral material will be reduced. The asphalt amount threshold is set in the range of 30% to 40%.

4. The method for targeted design of in-situ hot-regeneration mixture based on discontinuous blending strategy according to claim 1 is characterized in that: The indoor test adopts an extraction test or a combustion test.

5. The method for targeted design of in-situ hot-regeneration mixture based on discontinuous blending strategy according to claim 1 is characterized in that: The method also includes: adding a first set amount and a second set amount of asphalt to the final recycled mixture determined in step six, respectively, to form a first recycled mixture and a second recycled mixture respectively; performing Marshall tests on the final recycled mixture, the first recycled mixture and the second recycled mixture, respectively, and selecting the recycled mixture with the highest stability in the Marshall test as the best recycled mixture; the second set amount is equal to 2 times the first set amount, and the range of the first set amount is 0.1% to 0.3%.

6. In-situ hot-recycled mixture based on discontinuous blending strategy, characterized by: The in-situ hot recycled mixture is prepared by using the in-situ hot recycled mixture targeted design method based on the discontinuous blending strategy described in any one of claims 1 to 5.

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