RUBBER PARTICLE-DOPED COMPOSITE CHIP SEAL AND CONSTRUCTION METHOD THEREOF

Abstract

Disclosed are a rubber particle-doped composite chip seal and a construction method thereof. The chip seal includes: a coarse aggregate in a lower layer, a fine aggregate in an upper layer, and an SBS-modified emulsified asphalt binding and encapsulating the coarse aggregate and the fine aggregate into a whole, wherein the coarse aggregate is a gravel having a particle size of 4.75 mm to 7.1 mm, the fine aggregate is rubber particles having a particle size of 1.18 mm to 4.75 mm after pre-treatment, and the fine aggregate has a doping amount of 30% to 45% of a volume of all aggregates.

Claims

1-17. (canceled)

18. A rubber particle-doped composite chip seal, comprising: a coarse aggregate in a lower layer; a fine aggregate in an upper layer; and a styrene-butadiene-styrene (SBS)-modified emulsified asphalt binding and encapsulating the coarse aggregate and the fine aggregate into a whole, wherein the coarse aggregate is a gravel having a particle size of 4.75 mm to 7.1 mm, the fine aggregate is rubber particles having a particle size of 1.18 mm to 4.75 mm after pre-treatment, and the fine aggregate has a doping amount of 30% to 45% of a volume of all aggregates.

19. The rubber particle-doped composite chip seal of claim 18, wherein the gravel is an alkaline gravel.

20-22. (canceled)

23. A method for construction of a rubber particle-doped composite chip seal, the method comprising: spreading an SBS-modified emulsified asphalt evenly on an existing pavement, then spreading a coarse aggregate, and then spreading a fine aggregate; and spreading a layer of an asphalt anti-stripping agent on the fine aggregate after the SBS-modified emulsified asphalt is solidified to obtain a specimen, and then subjecting the specimen to rolling compaction to smooth to obtain a complete chip seal.

24. The method for construction of the rubber particle-doped composite chip seal of claim 23, wherein the chip seal has a thickness of 6 mm to 12 mm.

25. The method for construction of the rubber particle-doped composite chip seal of claim 23, wherein the gravel is coarse aggregate is an alkaline gravel.

26-28. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIGURE shows a structural diagram of the chip seal according to an embodiment of the present disclosure.

[0034] In Figure, 1 represents rubber particles; 2 represents a gravel; and 3 represents an SBS-modified emulsified asphalt.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the examples of the present disclosure. Apparently, the described examples are merely a part, not all of the examples of the present disclosure. Based on the examples of the present disclosure, all other examples obtained by a person of ordinary skill in the art without creative efforts should fall within the scope of the present disclosure.

Example 1

[0036] This example provided a preferred method for pre-treating waste rubber particles for a chip seal, which was specifically performed as follows:

[0037] 1) A waste rubber tire was subjected to crushing, roller compaction, and grinding, obtaining untreated rubber particles having a particle size of 1.18 mm to 2.36 mm. The untreated rubber particles were placed in an alkali solution and subjected to alkali washing at 25 C. for 2 h, wherein the alkali solution was a mixed solution of NaClO and deionized water, with a concentration of 2%. After the alkali washing was finished, the resulting rubber particles were washed with distilled water until they were clear, then placed in an oven and dried until a mass of the washed rubber particles did not change, obtaining treated rubber particles. The treated rubber particles were taken out for later use.

[0038] 2) The treated rubber particles were placed in an ammonia-containing solution and subjected to ammoniation at 60 C. for 2 h, wherein the ammonia-containing solution was a mixed solution of urea and deionized water, with a concentration of 2%. After the ammoniation was finished, the resulting rubber particles were washed with distilled water until they were clear, then placed in the oven until a mass of the washed rubber particles did not change, obtaining pre-treated rubber particles. The pre-treated rubber particles were taken out for later use.

[0039] The pre-treated rubber particles were subjected to a brush test using a wet wheel abrasion meter. The brush test was performed as follows: 54 g of an SBS-modified emulsified asphalt was spread on an asphalt felt having a diameter of 280 mm, and then 120 g of the pre-treated rubber particles were weighted and spread on the SBS-modified emulsified asphalt, waiting for solidifying to be completed.

Comparative Example 1

[0040] This comparative example was different from Example 1 in that the rubber particles were untreated, and the remaining steps were the same as those in Example 1.

Comparative Example 2.1

[0041] This comparative example was different from Example 1 in that the rubber particles were subjected to alkali washing only with the alkali solution in Example 1, and the remaining steps were the same as those in Example 1.

Comparative Example 2.2

[0042] This comparative example was different from Example 1 in that the rubber particles were treated only with urea, and the remaining steps were the same as those in Example 1.

Comparative Example 2.3

[0043] This comparative example was different from Example 1 in that the rubber particles were subjected to the alkali washing with a mixed solution of NaOH and deionized water, with a concentration of 3%, and the remaining steps were the same as those in Example 1.

[0044] The results of the brush test of Example 1 and Comparative Examples 1 to 2 are summarized in Table 1. As shown in Table 1: compared with Example 1, the shedding rate of the rubber particles in Comparative Example 1 to 2 is higher than that in Example 1. The shedding rate in Comparative Example 1 reaches 50.31%, which is approximately 7.04 times that of Example 1. The shedding rate in Comparative Example 2.1 reaches 17.97%, which is approximately 2.51 times that of Example 1, The shedding rate in Comparative Example 2.2 reaches 21.69%, which is approximately 3.03 times that of Example 1. The shedding rate in Comparative Example 2.3 reaches 47.47%, which is approximately 6.64 times that of Example 1.

TABLE-US-00001 TABLE 1 Modification of rubber particles Serial Number Pre-treating Mode Brush shedding rate (%) Example 1 NaClO + urea 7.15 Comparative Example 1 No treatment 50.31 Comparative Example 2.1 NaClO 17.97 Comparative Example 2.2 Urea 21.69 Comparative Example 2.3 NaOH 47.47

[0045] Although both NaClO and NaOH have strong oxidizing properties, NaClO solution can oxidize the CC double bonds in rubber particles to break the bonds, and the oxidation generates carbonyl groups. The polar groups, amino and carbonyl, are grafted on the surface of rubber particles by treatment with urea solution, thereby increasing the wettability of rubber particles and emulsified asphalt. At the same time, these groups react with groups in the asphalt at the interface area to increase the interface bonding strength. The adhesion between the rubber particles and the emulsified asphalt can be further increased by treating the rubber particles with NaClO solution and urea. The pre-treatment effect of NaClO or urea alone is lower than that of NaClO and urea.

Example 2

[0046] This example provided a rubber particle-doped composite chip seal, consisting of a coarse aggregate in a lower layer, a fine aggregate in an upper layer, and an SBS-modified emulsified asphalt binding and encapsulating the coarse aggregate and the fine aggregate into a whole, wherein the coarse aggregate was a gravel having a particle size of 4.75 mm to 7.1 mm; and the fine aggregate was the rubber particles having a particle size of 1.18 mm to 2.36 mm pre-treated according to Example 1.

[0047] A production process of a traditional composite-gradation chip seal specimen was performed as follows:

[0048] At room temperature, a corresponding mass of SBS-modified emulsified asphalt was accurately weighed and spread on an asphalt felt with a spreading diameter of 280 mm. A limestone was subjected to a first spreading, that is, the limestone was spread on an upper layer of the SBS-modified emulsified asphalt, wherein a volume of the limestone accounted for 50% to 70%, and the limestone had a particle size of 4.75 mm to 7.1 mm. Then the limestone was subjected to a second spreading, wherein a volume of the limestone accounted for 30% to 50%, and the limestone had a particle size of 1.18 mm to 2.36 mm, obtaining a specimen. After the specimen was subjected to full rolling compaction, a chip seal specimen was completely solidified for later use.

[0049] In order to test the performance of the rubber particle-doped composite chip seal, a rubber particle-doped composite chip seal specimen was produced in this example. The differences between the production processes of the rubber particle-doped composite chip seal specimen and the traditional composite-gradation chip seal were as follows: under the condition that the amount of the limestone in the first spreading kept unchanged, the limestone in the second spreading was replaced with the same volume of the rubber particles obtained after pre-treatment as in Example 1. The pre-treated rubber particles were spread on an upper layer of a gravel in the first spreading, wherein a volume of the pre-treated rubber particles accounted for 30% to 50%, and a particle size of the pre-treated rubber particles was 1.18 mm to 2.36 mm, obtaining a specimen. After the specimen was subjected to full rolling compaction, a chip seal specimen was completely solidified for later use.

[0050] It should be noted that the amount of the gravel was determined by a design method of a Shaanxi chip seal. That is, the gravel was spread all over a rut plate test mold, and a spreading amount of the gravel per unit area was converted by calculating a gravel mass and a rut plate test mold area. The spreading amount of the gravel per unit area was shown in Table 2, and the internal dimension of the rut plate test mold was 30 cm30 cm. The amount of the gravel was calculated according to formula (1):

[00005]$\begin{array}{cc}{m}_s=\mathrm{AAR}{S}_s{r}_i& \left(1\right)\end{array}$

[0051] wherein m.sub.S represents the amount of the gravel (g); AAR represents a spreading amount of the gravel per unit area (kg/m.sup.2); r.sub.1 represents a spreading proportion of an i-th type of the gravel (%); and S.sub.S represents a spreading area (m.sup.2), wherein the asphalt felt had an area of 0.0616 m.sup.2.

TABLE-US-00002 TABLE 2 Spreading amount of the gravel per unit area Particle size of gravel 7.1-9.5 mm 4.75-7.1 mm 2.36-4.75 mm Mass of gravel used (g) 894 693 423 spreading amount AAR 9.93 7.70 4.70 (kg/m.sup.2)

[0052] It should be noted that for composite-gradation chip seal, the amount of the asphalt was calculated according to formula (2):

[00006]$\begin{array}{cc}{m}_A=\left({\mathrm{EAR}}_1{r}_1+{\mathrm{EAR}}_2{r}_2\right)S_A& \left(2\right)\end{array}$

[0053] wherein m.sub.A represents an amount of the SBS-modified emulsified asphalt (g); EAR.sub.1 and EAR.sub.2 represent spreading amounts of asphalts corresponding to the coarse aggregate and the fine aggregate, respectively (L/m.sub.2); r.sub.1 and r.sub.2 represent spreading proportions of the coarse aggregate and the fine aggregate, respectively (%); and SA represents a spreading area (m.sup.2); wherein the asphalt felt had an area of 0.0616 m.sup.2.

[0054] The spreading amount of the asphalt was determined according to formulas (3) and (4) based on a McLeod Design calculation method:

[00007]$\begin{array}{cc}\mathrm{EAR}=\frac{\frac{0.2}{0.5}VHT+S+A}{R}& \left(3\right)\end{array}$$\begin{array}{cc}H=\frac{M}{1.139285+0.011506\mathrm{FI}}& \left(4\right)\end{array}$

[0055] wherein EAR represents the spreading amount of the asphalt (L/m.sup.2); V represents a void ratio of a loose gravel (%); H represents an average minimum size of the gravel (mm); T represents a traffic volume correction factor; S represents a road condition correction factor; A represents an amount of the asphalt absorbed by the gravel (g); R represents a solid content of the emulsified asphalt (g); M represents a median size of the gravel (mm); FI represents a needle flake index; G represents a relative bulk density of a gross volume; W represents a unit mass of the loose gravel (kg/m.sup.3); and E represents an aggregate loss coefficient.

[0056] Since this example is an indoor experiment, partial values in formulas (2) to (4) are as follows: E=1, S=0; a residual content of the emulsified asphalt is about 55.5%, taking R=0.555, considering low-grade traffic highways and taking T=0.75; it was generally believed that the absorption rate of the asphalt by the gravel is 1%, and the amount of the asphalt increases by about 0.09 L/m.sup.2, such that A=0.09 is at this time.

[0057] The calculation results of the spreading amount of the asphalt are shown in Table 3. In this example, only the pre-treated rubber particles are used to replace the fine aggregate (small particle-size gravel) in the traditional composite-gradation chip seal, and the amount of the asphalt does not change with the rubber particles. Therefore, by substituting the data in Table 2 into formula (2), the total amount of the SBS-modified emulsified asphalt in the rubber particle-doped composite chip seal specimen can be obtained.

TABLE-US-00003 TABLE 3 Calculation table for the spreading amount of the asphalt Calculation Particle size range of gravel parameters 7.1-9.5 mm 4.75-7.1 mm 2.36-4.75 mm M (mm) 8.3 5.9 3.5 FI (%) 12.0 10.7 8.2 H (mm) 6.50 4.67 2.77 W 1386 1375 1369 G 2.665 2.661 2.658 V (%) 48.0 48.3 48.5 E 1 1 1 T 0.75 0.75 0.75 S 0 0 0 A 0.09 0.09 0.09 R 0.555 0.555 0.555 EAR (L/m.sup.2) 1.85 1.38 0.91

[0058] In should be noted that according to the doping amount of the rubber particle in this example, the gravel having the same particle size is replaced by the rubber particles (namely the fine aggregate) by an equal volume method. An amount of the repalced gravel is calculated according to formula (1), and the amount of the rubber particle is calculated according to formula (5):

[00008]$\begin{array}{cc}{m}_R=\frac{m_S}{{}_S}{}_R& \left(5\right)\end{array}$

[0059] wherein m.sub.R represents the amount of the rubber particle (g); m.sub.S represents a mass of the gravel having the same particle size replaced by the rubber particles by equal volume method according to the amount of the rubber particle (g); .sub.S represents an apparent density of the gravel (g/cm.sup.3); and .sub.R represents an apparent density of the rubber particles (g/cm.sup.3).

Comparative Example 3

[0060] This comparative example was different from Example 2 in that the spread rubber particles had a particle size of 2.36 mm to 4.75 mm, and the remaining steps were the same as those in Example 2.

[0061] The chip seal specimens in Example 2 and Comparative Example 3 were subjected to a noise test using the indoor tire accelerated sliding test, and measured with a decibel meter. The test results are shown in Table 4. Table 4 also includes the amounts of the rubber particles and the sphalt calculated in Example 2 and Comparative Example 3.

TABLE-US-00004 TABLE 4 Noise value of tire rolling and falling Rubber Rubber Decibel value/dB particle particle Asphalt Comparative doping amount amount/g amount/g Example 2 Example 3 30% 36.7 76.3 65.5 65.6 35% 42.8 74.9 64.6 64.8 40% 48.9 73.4 63.9 64.1 45% 55.0 71.9 63.3 63.6 50% 61.1 70.5 63.0 63.4

[0062] As shown in Table 4:

[0063] 1) As the doping amount of the rubber particles increases from 30% to 50%, the decibel values generated by the chip seal specimens in Comparative Example 3 and Example 2 gradually decrease. Example 2 is reduced from 65.5 dB to 63.0 dB, and Comparative Example 3 is reduced from 65.6 dB to 63.4 dB. This indicates that increasing the doping amount of the rubber particles can improve the sound absorption capacity of chip seal pavement and reduce the noise generated by tire pumping.

[0064] 2) When the rubber particle size increases from 1.18 mm to 2.36 mm to 2.36 mm to 4.75 mm, the overall decibel value of Example 3 is higher than that of Comparative Example 2. That is to say, the increase in the particle size of the rubber particles has a certain impact on the sound absorption capacity of chip seal pavement. Moreover, the greater the doping amount of the rubber particles, the more obvious this effect is.

[0065] A tire vertical vibration attenuation test was conducted to conduct the vibration attenuation test on Example 2 and Comparative Example 3. The tires used were van tires (tire pressure 0.25 MPa, 165/70R13). The test results are shown in Table 5. As shown in Table 5, as the doping amount of the rubber particles increases, the vibration attenuation coefficient gradually increases, but the growth rate slows down after 45%. This indicates that when the doping amount of the rubber particles is in a range of 30% to 45%, the rubber particle-doped composite chip seal has a desirable shock absorption effect. Comparing Example 2 and Comparative Example 3, the particle size of the rubber particles increases and the shock absorption effect is improved.

TABLE-US-00005 TABLE 5 Test results of tire free vibration attenuation of chip seal Rubber particle Vibration attenuation coefficient doping amount Example 2 Comparative Example 3 0% 5.554 5.554 30% 5.954 6.047 35% 6.137 6.250 40% 6.456 6.756 45% 6.614 6.935 50% 6.708 7.027

Comparative Example 4

[0066] This comparative example was different from Example 2 in that the gravel in the first spreading had a particle size of 7.1 mm to 9.5 mm, and the rubber particles in the second spreading had a particle size of 2.36 mm to 4.75 mm, and the remaining steps were the same as in Example 2.

Comparative Example 5

[0067] This comparative example was different from Example 2 in that the gravel in the first spreading had a particle size of 7.1 mm to 9.5 mm, and the rubber particles in the second spreading had a particle size of 4.75 mm to 7.1 mm, and the remaining steps were the same as in Example 2.

[0068] The products obtained in Example 2, Comparative Example 3, Comparative Example 4, and Comparative Example 5 were subjected to a 5-min brush test using a wet wheel abrasion meter, wherein the rubber particles used in the brush test included untreated rubber particles and pre-treated rubber particles. The test results are shown in Table 6.

TABLE-US-00006 TABLE 6 Results of brush test Particle Proportion Shedding rate (%) Particle size of the of the Untreated Pre-treated Experimental size of the rubber rubber rubber rubber group gravel particles particles particles particles Comparative 7.1-9.5 4.75-7.1 30% 19.09 11.68 Example 5 mm mm 35% 22.17 13.26 40% 28.93 15.07 45% 40.51 19.75 50% 48.59 24.19 Comparative 7.1-9.5 2.36-4.75 30% 14.32 7.59 Example 4 mm mm 35% 17.74 8.93 40% 23.62 11.73 45% 27.26 14.54 50% 34.89 17.29 Comparative 4.75-7.1 2.36-4.75 30% 9.61 5.63 Example 3 mm mm 35% 12.37 7.02 40% 15.79 8.48 45% 20.58 9.42 50% 24.79 13.09 Example 2 4.75-7.1 1.18-2.36 30% 7.05 3.85 mm mm 35% 8.86 4.71 40% 11.62 5.36 45% 13.05 6.97 50% 15.46 8.14

[0069] As shown in Table 6

[0070] 1) For the untreated rubber particle-doped chip seal, when the particle size of the gravel is determined, with the same proportion of the rubber particles, the brush shedding rate increases as the particle size of the rubber particles increases. The average shedding rates of the rubber particles at different proportions in Comparative Example 5, Comparative Example 4, Comparative Example 3, and Example 2 are 31.9%, 23.6%, 16.6%, and 11.2%, respectively. This indicates that reducing in the particle size of the rubber particles can effectively reduce the brush shedding rate of the chip seal, and the shedding rate of Example 2 is much lower than that of Comparative Examples 3, 4, and 5.

[0071] 2) In the pre-treated rubber particle-doped chip seal, the overall shedding rate of the chip seal can also be reduced, with the same law as that of the untreated rubber particle-doped chip seal. Moreover, the average shedding rates of the rubber particles at different proportions in Comparative Example 5, Comparative Example 4, Comparative Example 3, and Example 2 are 16.8%, 12.0%, 8.7%, and 5.8%, which are reduced by 47.3%, 49.1%, 47.6%, and 48.2%, respectively, compared with the untreated rubber particle-doped chip seal. Obviously, the use of the pre-treated rubber particles in the chip seal can significantly reduce the brush shedding rate of the rubber particles.

[0072] 3) For the gravel and rubber particles having specific particle sizes, the proportion of rubber particles increases and the shedding rate of the chip seal increases.

[0073] Comparative Example 6

[0074] This comparative example was different from Example 2 in that the gravel in the first spreading had a particle size of 7.1 mm to 9.5 mm, and the gravel in the second spreading had a particle size of 4.75 mm to 7.1 mm, and the remaining steps were the same as in Example 2.

Comparative Example 7

[0075] This comparative example was different from Example 2 in that the gravel in the first spreading had a particle size of 7.1 mm to 9.5 mm, and the gravel in the second spreading had a particle size of 2.36 mm to 4.75 mm, and the remaining steps were the same as in Example 2.

Comparative Example 8

[0076] This comparative example was different from Example 2 in that the gravel in the first spreading had a particle size of 4.75 mm to 7.1 mm, and the gravel in the second spreading had a particle size of 2.36 mm to 4.75 mm, and the remaining steps were the same as in Example 2.

Comparative Example 9

[0077] This comparative example was different from Example 2 in that the gravel in the first spreading had a particle size of 4.75 mm to 7.1 mm, and the gravel in the second spreading had a particle size of 1.18 mm to 2.36 mm, and the remaining steps were the same as in Example 2.

[0078] The chip seal specimens in Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, Comparative Example 6, Comparative Example 7, Comparative Example 8, and Comparative Example 9 were subjected to a brush noise test using a wet wheel abrasion test and a decibel meter. The anti-skid performance of the chip seal specimens was evaluated with reference to a manual sand laying method and the pendulum friction meter method in the Field Test Methods of Highway Subgrade and Pavement (JTG 3450-2019). The particle size comparison and test results of the gravel and rubber particles in Example 2 and Comparative Examples 3 to 9 are shown in Table 7 and Table 8.

TABLE-US-00007 TABLE 7 Brush noise and anti-skid performance of the rubber particle-doped composite chip seal Proportion Particle Particle size of the Experimental size of the of the rubber rubber Structural group gravel/mm particles/mm particles L.sub.10 L.sub.50 L.sub.90 L.sub.eq depth Example 2 4.75-7.1 1.18-2.36 30% 77.9 76.2 75.3 76.3 2.18 35% 77.5 75.9 75.0 76.0 2.05 40% 75.4 75.5 73.4 75.6 1.97 45% 75.6 74.9 73.0 75.0 1.83 50% 75.4 74.7 72.6 74.8 1.64 Comparative 4.75-7.1 2.36-4.75 30% 77.5 76.4 74.8 76.5 2.57 Example 3 35% 77.1 76.2 74.2 76.3 2.50 40% 76.5 75.7 73.9 75.8 2.34 45% 75.8 75.5 73.5 75.6 2.22 50% 75.8 75.1 73.1 75.2 2.08 Comparative 7.1-9.5 2.36-4.75 30% 79.2 77.5 76.8 77.6 3.20 Example 4 35% 78.7 77.6 76.6 77.7 3.02 40% 78.3 77.4 75.8 77.5 3.04 45% 78.6 77.2 76.1 77.3 2.87 50% 78.4 76.8 75.9 76.9 2.77 Comparative 7.1-9.5 4.75-7.1 30% 79.7 78.1 77.7 78.2 3.44 Example 5 35% 79.0 77.7 76.5 77.8 3.30 40% 78.9 77.8 76.4 77.9 3.29 45% 78.7 77.7 76.6 77.8 3.25 50% 78.3 77.2 76.2 77.3 3.01 Notes L.sub.10 represents a noise level exceeded 10% of the time during the test, which is equivalent to an average peak value of the noise; L.sub.50 represents a noise level exceeded 50% of the time during the test, which is equivalent to an average of the noise; L.sub.90 represents a noise level exceeded 90% of the time during the test, which is equivalent to a background value of the noise; L.sub.eq represents a continuous sound level during the test; Structural depth: evaluating the roughness of the pavement; the smaller the structural depth, the closer the gravel arrangement and the better the anti-skid performance are.

TABLE-US-00008 TABLE 8 Brush noise of the chip seal without doping rubber particles Particle size Particle size of the gravel of the gravel in the Proportion of in the first second small-particle- Experimental spreading/ spreading/ size Structural group mm mm aggregates L.sub.10 L.sub.50 L.sub.90 L.sub.eq depth Comparative 7.1-9.5 4.75-7.1 30% 80.3 78.6 77.8 78.7 3.30 Example 6 35% 79.5 78.5 77.2 78.6 3.27 40% 79.7 78.6 77.5 78.7 3.10 45% 79.8 78.5 76.7 78.7 3.12 50% 79.4 78.5 77.5 78.6 2.88 Comparative 7.1-9.5 2.36-4.75 30% 80.5 78.5 77.6 78.6 3.19 Example 7 35% 79.8 78.5 77.5 78.6 2.85 40% 79.6 78.4 77.2 78.5 2.87 45% 80.3 78.4 78.2 78.5 2.73 50% 79.8 78.4 77.9 78.5 2.64 Comparative 4.75~7.1 2.36~4.75 30% 79.1 77.8 76.5 77.9 2.31 Example 8 35% 78.6 77.7 76.2 77.8 2.37 40% 78.8 77.5 76.1 77.6 2.21 45% 78.5 77.6 76.5 77.7 2.12 50% 78.3 77.5 75.5 77.6 1.84 Comparative 4.75~7.1 1.18~2.36 30% 78.8 77.5 76.8 77.6 2.10 Example 9 35% 78.6 77.6 76.7 77.7 1.96 40% 78.3 77.4 76.5 77.5 1.90 45% 78.3 77.3 76.3 77.4 1.70 50% 78.5 77.3 76.4 77.4 1.55 Notes L.sub.10 represents a noise level exceeded 10% of the time during the test, which is equivalent to an average peak value of the noise; L.sub.50 represents a noise level exceeded 50% of the time during the test, which is equivalent to an average of the noise; L.sub.90 represents a noise level exceeded 90% of the time during the test, which is equivalent to a background value of the noise; L.sub.eq represents a continuous sound level during the test; Structural depth: evaluating the roughness of the pavement; the smaller the structural depth, the closer the gravel arrangement and the better the anti-skid performance are.

[0079] It can be seen from Tables 7 and 8 that:

[0080] 1) The average noise values of Comparative Example 5, Comparative Example 4, Comparative Example 3, and Example 2 are 77.8 dB, 77.4 dB, 75.9 dB, and 75.5 dB, respectively. The average noise values of Comparative Examples 9, 8, 7, and 6 are 78.6 dB, 78.5 dB, 77.7 dB, and 77.5 dB, which are reduced by 0.8 dB, 1.1 dB, 1.8 dB, and 2.0 dB, respectively, compared with the chip seal without doping rubber particles. In Comparative Examples 5 and 4, the gravels have a particle size of 7.1 mm to 9.5 mm. Compared with Comparative Examples 6 and 7, the reduction in the noise value is not significant, even if partial rubber particles are added, while the noise values in Comparative Example 3 and Example 2 are reduced by 1.8 dB and 2.0 dB, respectively. The result indicates that the particle size of the coarse aggregate (gravel) in the chip seal has a greater influence on the noise value. The selection of the gravel having a particle size of 4.75 mm to 7.1 mm in combination with the rubber particles can effectively reduce the brush noise of the chip seal.

[0081] The reason for the reduction in the brush noise of the chip seal is that the rubber particles have a desirable elasticity and play a buffering role in the chip seal. When the brush head contacts the chip seal, the rubber particles deform to store energy. After the brush head leaves the chip seal, the rubber particles resume their deformation. Compared with the direct collision between the gravel and the rubber pipes, this process reduces the impact and vibration, thereby reducing the noise value.

[0082] 2) For the chip seal without doping rubber particles, the particle size of the gravel in the first spreading is reduced from 7.1 mm to 9.5 mm to 4.75 mm to 7.1 mm, and the structural depth decreases accordingly. For example, the average structural depth in Comparative Example 6 is 3.13 mm, and the average structural depth in Comparative Example 8 is 2.17 mm, which is reduced by 30.7% compared with that of Comparative Example 6. This is mainly due to the large gaps when the gravel having large-diameter is arranged in a single layer. The reduction in the particle size can make the arrangement of the gravel tighter, such that the smoothness and slip resistance of the surface of the chip seal are slightly improved.

[0083] Comparing the structural depths of the chip seal with and without doping rubber particles, it can be seen that the structural depth of the chip seal with doping rubber particles has an upward trend. Taking the proportion of the fine aggregate (rubber particles or small-sized gravel) at 30% as an example, the structural depths of Comparative Example 5, Comparative Example 4, Comparative Example 3, and Example 2 are 3.44 mm, 3.20 mm, 2.57 mm, and 2.18 mm, respectively, while the structural depths of Comparative Examples 6, 7, 8, and 9 are 3.30 mm, 3.19 mm, 2.31 mm, and 2.10 mm, respectively, which are slightly lower than those of the former. Analysis of the reasons for this shows that the rubber particles have the characteristics of high elasticity, which is prone to rebound during the compaction process, resulting in some gaps between the rubber particles. Therefore, the structural depth of the rubber particle-doped composite chip seal increases slightly, but has no significant increase, indicating that the rubber particles have little influence on the slip resistance performance of the chip seal.

[0084] Combining Tables 4 to 8, it can be seen that the vibration reduction effect of Comparative Example 3 is better than that of Example 2. However, since the rubber particles of Comparative Example 3 have a larger particle size than those of Example 2, the brush shedding rate of Example 2 is much better. Generally speaking, Example 2 has the best overall performance. However, when the practical engineering requires higher shock absorption for the chip seal, the gravel and rubber particles in Comparative Example 3 can also be selected.

Example 3

[0085] Specific steps were performed as follows:

[0086] At room temperature, 73.4 g of an SBS-modified emulsified asphalt (shown in Table 4) was accurately weighed and spread on an asphalt felt with a spreading diameter of 280 mm. A first spreading was conducted, that is, a gravel was spread on an upper layer of the SBS-modified emulsified asphalt, wherein the gravel was limestone with a mass of 284.5 g, a volume proportion of 60%, and a particle size of 4.75 mm to 7.1 mm. Then a second spreading was conducted, that is, rubber particles pre-treated as the manner in Example I were spread on an upper layer of the gravel, wherein the rubber particles had a mass of 48.9 g, a volume proportion of 40%, and a particle size of 1.18 mm to 2.36 mm, obtaining a specimen. The specimen was subjected to full rolling compaction, obtaining a chip seal specimen. After the chip seal specimen was completely solidified, the solidified chip seal specimen was subjected to an accelerated loading test using a wheel loader, and the loading conditions were 0.3 MPa and 120 times/min, respectively.

Comparative Example 10

[0087] This comparative example was different from Example 3 in that the volume proportion of the limestone accounted for 70%, the volume proportion of the rubber particles accounted for 30%, and the remaining steps were the same as in Example 3.

Comparative Example 11

[0088] This comparative example was different from Example 3 in that the volume proportion of the limestone accounted for 65%, the volume proportion of the rubber particles accounted for 35%, and the remaining steps were the same as in Example 3.

Comparative Example 12

[0089] This comparative example was different from Example 3 in that the volume proportion of the limestone accounted for 55%, the volume proportion of the rubber particles accounted for 45%, and the remaining steps were the same as in Example 3.

Comparative Example 13

[0090] This comparative example was different from Example 3 in that the volume proportion of the limestone accounted for 50%, the volume proportion of the rubber particles accounted for 50%, and the remaining steps were the same as in Example 3.

[0091] Test results of Example 3 and Comparative Examples 10 to 13 are shown in Table 9. It can be seen from Table 9 that:

[0092] When the mass proportion of the gravel to the rubber particles is fixed, as the number of loading times increases, the shedding rate of the rubber particles in the chip seal specimens in Example 3 and Comparative Examples 10 to 13 gradually increases. When the loading times are the same and the mass proportion of the rubber particles gradually increases from 30% to 50%, the shedding rate of the rubber particles decreases and then increases. There is a minimum shedding rate when the mass proportion of the rubber particles is 40%. When the number of the loading times is 100,000, the shedding rate of the chip seal specimen in Example 3 is only 30.46%, and that of Comparative Example 11 is 34.25%. it can be seen that when the proportion of the rubber particles is in a range of 35% to 40%, the shedding rate of the chip seal is extremely low and the sound absorption capacity of the pavement is strong. According to the results of Example 3 and Comparative Example 12, it is inferred that when the proportion of the rubber particles is in a range of 40% to 43%, the shedding rate of the chip seal is lower and the sound absorption capacity of the pavement is also stronger.

TABLE-US-00009 TABLE 9 Long-term shedding rate Proportion of the Shedding rate (%) Serial rubber 5,000 10,000 20,000 40,000 60,000 100,000 Number particles times times times times times times Comparative 30% 9.57 17.30 22.09 29.09 32.40 37.19 Example 10 Comparative 35% 5.52 11.80 16.94 24.36 28.92 34.25 Example 11 Example 3 40% 4.35 10.29 16.22 22.15 25.71 30.46 Comparative 45% 6.61 13.42 20.64 27.46 31.38 36.13 Example 12 Comparative 50% 8.54 19.63 26.25 32.86 36.49 42.25 Example 13

[0093] To sum up, in the pre-treatment tests of Example 1 and Comparative Examples 1 to 2, the rubber particles treated with NaClO solution and urea solution have the best adhesion to the SBS-modified emulsified asphalt and the lowest shedding rate, followed by the pre-treatment mode using NaClO or urea alone. In the brush test of the chip seal specimens in Example 2 and Comparative Examples 3 to 5, the chip seal prepared with SBS-modified emulsified asphalt, 4.75 mm to 7.1 mm of gravel, and 1.18 mm to 2.36 mm of pre-treated rubber particles in Example 2 have the lowest shedding rate, followed by the chip seal prepared with 2.36 mm to 4.75 mm of pre-treated rubber particle in the Comparative examples. In the brush noise test of Example 2 and Comparative Examples 3 to 9, when the doping amount of the rubber particles is greater than 40%, the noise reduction rate of the chip seal-based pavement slows down, and the reduction is more obvious after 45%. In addition, when the doping amount of the rubber particles is too large, the brush shedding rate of the chip seal increases rapidly. Therefore, it is better to control the doping amount of the rubber particles in a range of 30% to 45%, preferably within 35% to 40%. Through the tire accelerated sliding noise test in Example 2 and Comparative Example 3, it can be seen that the larger particle size of gravel makes the noise of the chip seal louder, so the gravel particle size is controlled doping amount 4.75 mm to 7.1 mm. Through the accelerated loading test of Example 3 and Comparative Examples 10 to 13 to simulate the actual shedding of the rubber particle-doped composite chip seal, for the chip seal composed of SBS-modified emulsified asphalt, 4.75 mm to 7.1 mm of the gravel, and 1.18 mm to 2.36 mm of the rubber particles, when the doping amount of the rubber particles is in a range of 30% to 45%, the shedding rate of the chip seal is lower, the pavement has a stronger sound absorption capacity. The above properties are most stable at a doping amount of 35% to 40%, leading to a lower long-term shedding rate.

Example 4

[0094] This example provided a method for constructing a rubber particle-doped composite chip seal, which was performed as follows: an SBS-modified emulsified asphalt was spread evenly on an existing pavement, then a gravel was spread, and then pre-treated rubber particles prepared according to Example 1 were spread, obtaining a specimen. Then the specimen was subjected to full rolling compaction to smooth, obtaining a complete chip seal. The rubber particle-doped composite chip seal obtained after construction had a thickness of 6 mm to 12mm, and preferably 8 mm to 10 mm.

[0095] Specifically, when the gravel had a particle size of 4.75 mm to 7.1 mm, the rubber particles had a particle size of 1.18 mm to 2.36 mm, and the rubber particles had a doping amount of 40%, the rubber particle-doped composite chip seal obtained after construction had a thickness of about 10 mm.

[0096] This example had the following beneficial effects:

[0097] Suitable spreading proportion and particle size ranges of the gravel and the rubber particles are adopted to make the interlocking between the aggregates and rubber particles tighter, thereby improving the service life of the rubber particle-doped composite chip seal, and providing the road sound absorption performance, shock absorption performance and driving comfort. The above construction of the chip seal is conducted at room temperature, without heating, pre-mixing and other steps, which greatly reduces the number of construction steps and greatly improves the efficiency of the construction, while also avoiding the problem of the segregation of the coarse and fine aggregates (the gravel) during the spreading. When the pre-treated rubber particles have a particle size of 1.18 mm to 2.36 mm and a doping amount of 35% to 40%, the overall performance of the chip seal is the best.

[0098] Contents not detailed in the present disclosure may be the prior art.

[0099] The above descriptions are only the preferred embodiments of the present disclosure, but not to limit the scope of the present disclosure. Any modifications, equivalent substitutions, and improvements made within the spirit and scope of the present disclosure should fall within the scope of the present disclosure.