A non-full-thickness cement pavement overlay material and its construction process

Abstract

This invention discloses a non-full-thickness cement pavement overlay material and its construction process. The non-full-thickness cement pavement overlay material is composed of basalt, shape memory particles, limestone powder, and high-elasticity modified asphalt. It can improve the crack resistance of the stress-absorbing layer, delay longitudinal reflective cracking, and extend the service life of the pavement. The construction process involves fine milling the cement pavement to create grooves on the surface; uniformly applying a high-strength interlayer adhesive across the entire pavement; then, spreading the non-full-thickness cement pavement overlay material on top of the high-strength interlayer adhesive as a stress-absorbing layer. This pavement structure can reduce the consumption of building materials such as stone and asphalt by approximately 30%, resulting in significant environmental and economic benefits. Finally, after the non-full-thickness cement pavement overlay material is constructed, a 4-5cm thick wearing layer is applied on top, effectively enhancing the surface wear resistance, extending the service life of the pavement, and improving driving comfort and safety.

Description

Technical Field

[0001] This invention belongs to the field of highway maintenance technology, specifically relating to a non-full-thickness cement pavement overlay material and its construction process. Background Technology

[0002] Cement pavement has excellent load-bearing capacity and durability, possessing advantages such as high strength, high load-bearing capacity, wear resistance, and impact resistance. Even after long-term use, cement pavement still retains significant economic value. Currently, maintenance and renovation are the main means of maximizing its remaining value. Asphalt pavement has advantages such as good toughness, seamless construction, low noise, and rapid construction. Therefore, most urban road standard sections use a combination of these two pavement structures, designing the vehicular road surface as cement pavement and the non-motorized vehicle road surface as asphalt pavement. In recent years, to improve pavement service performance, large-scale overlaying of asphalt onto cement pavements has begun.

[0003] If the cracking properties of the old cement pavement and asphalt pavement are not properly addressed during the renovation process, and an asphalt concrete layer is directly added, the longitudinal joints of the rigid-flexible overlap will quickly reflect onto the asphalt concrete layer under the action of external traffic loads and temperature cycles, forming longitudinal reflective cracks in the asphalt concrete layer. This seriously affects the performance of the added layer, making the added asphalt concrete extremely prone to cracking and causing adverse social impacts.

[0004] To improve the crack resistance of asphalt concrete, the common practice is to increase the thickness of the asphalt concrete layer, generally not less than 10cm, which is called full-thickness overlay. A stress-absorbing layer can also be set between the cement concrete pavement and the asphalt concrete layer. However, because the road surface elevation is raised after the cement pavement is overlaid with asphalt concrete, it is not used in bridge and tunnel sections with height restrictions. In addition, the increase in road surface elevation will also require corresponding modification and improvement of the roadside guardrails, further increasing the project cost.

[0005] Non-full-thickness asphalt overlays are thinner than full-thickness overlays, typically 6-7 cm thick. They mainly consist of a 4-5 cm upper anti-skid and wear-resistant layer and a lower stress-absorbing layer, with a bonding layer between the stress-absorbing layer and the original cement concrete pavement. However, reducing the overlay thickness can easily lead to a decrease in the crack resistance of the asphalt concrete. Summary of the Invention

[0006] This invention aims to at least partially solve one of the technical problems in the related art. Therefore, the main objective of this invention is to provide an asphalt concrete pavement structure for cement pavements, aiming to solve the problems of excessive pavement height after cement pavement overlay and decreased crack resistance of asphalt concrete after asphalt overlay due to reduced thickness.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A non-full-thickness cement pavement overlay material composition includes basalt, shape memory particles, limestone mineral powder, and high-elasticity modified asphalt.

[0009] Furthermore, the non-full-thickness cement pavement overlay material is composed of basalt with a particle size of 5-10mm: basalt with a particle size of 0.1-3mm: shape memory particles: limestone powder: high-elasticity modified asphalt in a ratio of 50-60:18-23:17-25:3-6:6-9 by weight.

[0010] Furthermore, the shape memory particles are composed of waste rubber powder, isocyanate, and epoxidized soybean oil;

[0011] Furthermore, the shape memory particles are composed of a mixture of waste rubber powder, isocyanate, and epoxidized soybean oil in a mass ratio of 90:4:6.

[0012] Furthermore, the method for preparing the shape memory particles includes: 1) first cutting waste rubber into particles with a particle size of 2-4 mm, swelling them with an organic solvent for 1 hour; separating the swollen rubber powder with a filter screen, transferring it to an oven for drying, and obtaining waste rubber powder;

[0013] 2) After mixing the waste rubber powder from step 1) with isocyanate and epoxidized soybean oil, heat it to 110°C and then use a closed rubber mixing mill for plasticizing and mixing to obtain modified rubber. Then, apply 30MPa pressure to the modified rubber at 160°C to compress its volume to 85%-95% of the pressure-free state. After removing the pressure, place the modified rubber at -10°C for 2 hours and then cut it into particles with a particle size of 1mm to obtain shape memory particles.

[0014] Furthermore, the organic solvent is one or more of toluene, methanol, and castor oil;

[0015] Furthermore, the high-elasticity modified asphalt is a mixture of elasticizer, plasticizer and asphalt; the elasticizer is one or more of SBS, SEBS, and SIS; the plasticizer is one or two of dibutyl phthalate and dioctyl phthalate.

[0016] Furthermore, the preparation process of the high-elasticity modified asphalt is as follows: heat the base asphalt to 140°C, add 4%-8% of the asphalt mass fraction of the elasticity enhancer, stir for 8-15 minutes and raise the temperature to 170°C, shear at 5000 rpm for 50 minutes; finally add 1%-2% of the asphalt mass fraction of the plasticizer, stir for 25-35 minutes, and the high-elasticity modified asphalt is obtained.

[0017] This invention also provides a construction process for non-full-thickness cement pavement overlay materials, specifically including fine milling of the cement pavement to create grooves on the road surface; and uniformly applying a high-strength interlayer adhesive to the entire pavement at a rate of 0.3–0.5 kg / m². 2 Finally, a non-full-thickness cement pavement overlay material is spread on top of the high-strength interlayer adhesive as a stress-absorbing layer.

[0018] Furthermore, it also includes constructing a 4-5cm thick wearing course on top of the non-full-thickness cement pavement overlay material after the construction of the overlay material.

[0019] Furthermore, the groove depth is 1.2–1.7 mm, and the interlayer high-strength adhesive is prepared by shearing and stirring at 70% C for 1 h with hydrogenated C9 resin with a molecular weight of 1,000–2,000, SIS with a molecular weight of 150,000–200,000, matrix asphalt, and xylene in a ratio of 11:4:33:52.

[0020] Furthermore, the wear layer is composed of 10-15mm basalt, 5-10mm basalt, 0-5mm basalt, mineral powder, polyester fiber, and SBS modified asphalt in a mass ratio of 40:22:29:9:0.2:6.2.

[0021] Furthermore, the preparation and construction process of the non-full-thickness cement pavement overlay material is as follows: a mixture of basalt, limestone mineral powder and high-elasticity modified asphalt in the specified formula is mixed at a temperature of 180℃ for 45 seconds; then it is transported to the construction site and spread on the cement concrete pavement using a paver with a paving thickness of 1-2 cm, and then rolled 3-4 times with a steel wheel roller; after the temperature of the mixture drops to the range of 60-80℃, shape memory particles are sprinkled and rolled 1-2 times with a steel wheel roller.

[0022] Furthermore, the preparation process of the wear-resistant asphalt mixture is as follows: basalt and mineral powder are heated to 180°C, SBS modified asphalt is heated to 160°C, then basalt and polyester fiber are stirred for 10 seconds, SBS modified asphalt and mineral powder are added and stirred for 40 seconds to obtain the wear-resistant asphalt mixture.

[0023] Furthermore, the construction process of the wear course asphalt mixture is as follows: the asphalt mixture is spread on the base surface with a thickness of 4-5cm, and then compacted 4-5 times using a 12-ton steel wheel roller.

[0024] Compared with the prior art, the present invention has at least the following advantages:

[0025] 1) The bonding strength of commonly used emulsified asphalt adhesives in my country is 0.5-0.7MPa and 0.1-0.2MPa at 25℃ and 60℃, respectively. However, the high-strength interlayer adhesive in this application has a bonding strength of more than 1.0MPa and more than 0.4MPa at 25℃ and 60℃, respectively. The high-strength interlayer adhesive can solve the problem of insufficient bonding strength of ordinary adhesives at high temperatures.

[0026] 2) Improved crack resistance of asphalt concrete: By spreading non-full-thickness cement pavement overlay material as a stress-absorbing layer, the crack resistance of the stress-absorbing layer of the pavement structure is effectively improved, the longitudinal reflective cracking of the pavement is delayed, and the service life of the pavement is increased.

[0027] 3) It can reduce the consumption of building materials such as stone and asphalt in road overlay by about 30%, which has significant environmental and economic benefits.

[0028] (4) Reduce the rise in road elevation caused by road overlay and reduce the impact of road overlay on the clearance of tunnels and underpasses. Overlay can be carried out without modifying the old road guardrails, curbs and other ancillary facilities, which indirectly saves costs.

[0029] (5) Adding a wear layer to high-intercalation oil-rich asphalt can not only enhance the wear resistance of the surface layer and extend the service life of the road surface, but also improve driving comfort and safety. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0031] When a quantity, concentration, or other value or parameter is described as a range, preferred range, or preferred upper and lower limits, it should be understood that it is equivalent to specifically disclosing any range by combining any pair of upper or preferred values ​​with any lower or preferred values, regardless of whether the range is specifically disclosed. Unless otherwise stated, the numerical range values ​​listed herein include the endpoints of the range and all integers and fractions within that range.

[0032] Unless otherwise stated, all percentages, parts, ratios, etc. in this document are by mass.

[0033] The materials, methods, and embodiments described herein are exemplary and should not be construed as limiting unless otherwise stated.

[0034] Example 1

[0035] A non-full-thickness cement pavement overlay material, the raw material composition of the mixture includes: basalt with a particle size of 5-10mm: basalt with a particle size of 0.1-3mm: shape memory particles: limestone mineral powder: high-elasticity modified asphalt = 50:19:17:4:6 by mass.

[0036] The added shape memory particles are composed of a mixture of waste rubber powder, isocyanate, and epoxidized soybean oil in a mass ratio of 90:4:6.

[0037] The preparation method of shape memory particles includes: first, cutting waste rubber into particles with a particle size of 2-4 mm, and swelling them with toluene for 1 hour; separating the swollen rubber powder with a filter screen, transferring it to an oven for drying to obtain waste rubber powder; mixing the obtained waste rubber powder with isocyanate and epoxidized soybean oil, heating it to 110℃, and then using a closed rubber mixing mill for plasticizing and mixing to obtain modified rubber; then applying a pressure of 30 MPa to the modified rubber at 160℃ to compress its volume to 85%-95% of the pressure-free state; after removing the pressure, placing the modified rubber at -10℃ for 2 hours, and then cutting it into particles with a particle size of 1 mm.

[0038] The preparation process of high-elasticity modified asphalt is as follows: heat the base asphalt to 140℃, add 4% SBS by mass of asphalt, stir for 9 min and heat to 170℃, shear at 5000 rpm for 50 min; finally add 1% dibutyl phthalate by mass of asphalt and stir for 25 min.

[0039] Example 2

[0040] Same as Example 1, except that the non-full-thickness cement pavement overlay material composition includes: basalt with a particle size of 5-10mm: basalt with a particle size of 0.1-3mm: shape memory particles: limestone mineral powder: high-elasticity modified asphalt = 52:20:19:4:8 by weight.

[0041] Methanol is used to swell waste rubber during the preparation of shape memory particles.

[0042] The preparation process of high-elasticity modified asphalt is as follows: heat the base asphalt to 140℃, add 4% SEBS by mass of asphalt, stir for 9 minutes and heat to 170℃, shear at 5000 rpm for 50 minutes; finally add 2% dioctyl phthalate by mass of asphalt and stir for 28 minutes.

[0043] Example 3

[0044] Same as Example 1, except that the non-full-thickness cement pavement overlay material composition includes: basalt with a particle size of 5-10mm: basalt with a particle size of 0.1-3mm: shape memory particles: limestone mineral powder: high-elasticity modified asphalt = 58:22:24:6:9 by weight.

[0045] Castor oil is used to swell waste rubber during the preparation of shape memory particles.

[0046] The preparation process of high-elasticity modified asphalt is as follows: heat the base asphalt to 140℃, add 6% SEBS by mass of asphalt, stir for 9 min and heat to 170℃, shear at 5000 rpm for 50 min; finally add 2% by mass of asphalt mixture of dibutyl phthalate and dioctyl phthalate, and stir for 30 min.

[0047] Example 4

[0048] Same as Example 1, except that the non-full-thickness cement pavement overlay material composition includes: basalt with a particle size of 5-10mm: basalt with a particle size of 0.1-3mm: shape memory particles: limestone mineral powder: high-elasticity modified asphalt = 60:22:20:8:7.

[0049] In the preparation of shape memory particles, a mixture of methanol and castor oil is used to swell waste rubber.

[0050] The preparation process of high-elasticity modified asphalt is as follows: heat the base asphalt to 140℃, add 8% of the asphalt mass fraction of a mixture of SEBS and SIS, stir for 15 min and heat to 170℃, shear at 5000 rpm for 50 min; finally add 1% of the asphalt mass fraction of a mixture of dibutyl phthalate and dioctyl phthalate, and stir for 35 min.

[0051] Comparative Example 1

[0052] The non-full-thickness cement pavement overlay material provided in this comparative example has the same composition and proportion as that in Example 2, except that it does not contain shape memory particles and has not been modified by SBS and dibutyl phthalate; its preparation process is the same as that in Example 1.

[0053] Comparative Example 2

[0054] The non-full-thickness cement pavement overlay material provided in this comparative example has the same composition and proportion as that in Example 2. The difference is that the shape memory particles are waste rubber particles with a particle size of 2-4 mm, and no organic solvent swelling or modification treatment such as isocyanate and epoxidized soybean oil is used.

[0055] Comparative Example 3

[0056] The non-full-thickness cement pavement overlay material provided in this comparative example has the same composition and proportion as that in Example 2. The difference is that the high-elasticity modified asphalt is a base asphalt, that is, a base asphalt that has not been modified by SBS and dibutyl phthalate.

[0057] Furthermore, the construction process of the non-full-thickness cement pavement overlay material prepared in Examples 1-4 and Comparative Examples 1-3 of this application is as follows: Specifically, it includes fine milling the cement pavement to form grooves on the road surface (groove depth is 1.5mm); uniformly spraying an interlayer high-strength adhesive on the entire pavement; and spreading the non-full-thickness cement pavement overlay material on top of the interlayer high-strength adhesive as a stress-absorbing layer (the preparation and construction process of this non-full-thickness cement pavement overlay material is as follows: mixing a mixture of basalt, limestone mineral powder and high-elasticity modified asphalt at a temperature of 180°C for 4... 5s; then transport to the construction site, use a paver to spread it on the cement concrete road surface, the paving thickness is 1.5cm, and use a steel wheel roller to roll it 3-4 times; after the temperature of the mixture drops to the range of 70℃, spread shape memory particles, and use a steel wheel roller to roll it 1-2 times; after the construction is completed, construct a 4cm thick wearing course on top, composed of 10-15mm basalt, 5-10mm basalt, 0-5mm basalt, mineral powder, polyester fiber: SBS modified asphalt in a mass ratio of 40:22:29:9:0.2:6.2, and after paving, use a 12-ton steel wheel roller to roll it 4-5 times;

[0058] The high-strength interlayer adhesive is prepared by shearing and stirring at 70°C for 1 hour with hydrogenated C9 resin of molecular weight of 1000-2000, SIS of molecular weight of 150,000-200,000, Shell 70 base bitumen, and xylene in a ratio of 11:4:33:52.

[0059] The preparation process of the wear course asphalt mixture is as follows: basalt and mineral powder are heated to 180°C, SBS modified asphalt is heated to 160°C, then basalt and polyester fiber are stirred for 10 seconds, SBS modified asphalt and mineral powder are added and stirred for 40 seconds to obtain the wear course asphalt mixture.

[0060] The construction process for this wearing course asphalt mixture is as follows: the wearing course asphalt mixture is spread on the base surface with a thickness of 4cm, and then compacted 4 to 5 times using a 12-ton steel wheel roller.

[0061] Comparative Example 4

[0062] The non-full-thickness cement pavement overlay material provided in this comparative example has the same composition and proportions as that in Example 2. The difference lies in its preparation and construction process: a mixture of basalt, limestone powder, high-elasticity modified asphalt, and shape memory particles is mixed at 180°C for 45 seconds; then it is transported to the construction site and spread on the cement concrete pavement using a paver to a thickness of 1.5 cm, and compacted 3-4 times using a steel wheel roller. The remaining construction process is the same as in Example 2. This application uses Example 2 as an example to conduct performance tests on the non-full-thickness cement pavement overlay materials prepared in Example 2 and Comparative Examples 1-4. The results are shown in the table below:

[0063] Table 1 Comparison of Asphalt Mixture Performance

[0064]

[0065] As can be seen from the data in the table above, there is no significant difference in the bonding strength between the comparative example and the embodiment. This is because the main factor affecting the bonding strength is the interlayer bonding material. Both the embodiment and the comparative example use high-strength adhesives, and therefore both have high bonding strength.

[0066] Comparative Example 1, which did not use shape memory particles, showed significantly lower low-temperature bending strain than Example 2. The crack resistance of the mixture was significantly reduced after the shape memory particles were not used, and the dynamic stability characterizing the high-temperature performance of the mixture showed a slight increase.

[0067] The rubber granules used in Comparative Example 2 were not swollen or modified. Compared to Example 2, Comparative Example 2 showed a decrease in both low-temperature flexural strain and dynamic stability. This is because the unswollen and unmodified rubber granules have low elasticity and are difficult to fuse with asphalt, resulting in numerous interfaces within the stress-absorbing layer and preventing it from forming a cohesive whole.

[0068] Comparative Example 3 uses base asphalt, which has poor low-temperature performance and dynamic stability. This is mainly because the base asphalt lacks SBS modification and does not have an SBS cross-linked network structure inside. The asphalt modulus and elasticity are lower than those of SBS modified asphalt, resulting in a significant decrease in the performance of the mixture.

[0069] Comparative Example 4 uses shape memory particles mixed with asphalt, stone, etc., without the spreading process. Its low-temperature bending strain is less than that of Example 2. This is mainly because the shape memory particles are subjected to high temperature of 170℃-190℃ during the mixing process, which causes plastic deformation and expansion, and the shape memory function is damaged.

[0070] Based on the performance of the above embodiments and comparative examples, it can be seen that using swollen and modified shape memory materials can effectively improve the low-temperature crack resistance of stress absorption layers.

[0071] The non-full-thickness cement pavement overlay material of the present invention, when used for paving cement pavement asphalt concrete, results in a pavement with superior performance in all aspects compared to traditional pavement structures. Furthermore, it allows for a thinner pavement and significantly improves the crack resistance of the stress-absorbing layer.

[0072] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A non-full-thickness cement pavement overlay material, characterized in that, The non-full-thickness cement pavement overlay material is composed of basalt with a particle size of 5-10mm: basalt with a particle size of 0.1-3mm: shape memory particles: limestone powder: high-elasticity modified asphalt in a ratio of 50-60:18-23:17-25:3-6:6-9 by weight; wherein the preparation method of the shape memory particles includes: 1) First, cut the waste rubber into particles with a particle size of 2-4mm, and swell it with an organic solvent for 1 hour; use a filter screen to separate the swollen rubber powder, and transfer it to an oven to dry it to obtain waste rubber powder. 2) The waste rubber powder obtained in step 1) is mixed with isocyanate and epoxidized soybean oil in a mass ratio of 90:4:

6. After heating to 110°C, it is plasticized and mixed using a closed rubber mixing mill to obtain modified rubber. Then, the modified rubber is subjected to a pressure of 30MPa at 160°C to compress its volume to 85%-95% of the pressure-free state. After removing the pressure, the modified rubber is placed at -10°C for 2 hours and then sheared into particles with a particle size of 1mm to obtain shape memory particles. The preparation process of the high-elasticity modified asphalt is as follows: heat the base asphalt to 140°C, add 4%-8% of the asphalt mass fraction of the elasticity enhancer, stir for 8-15 minutes and heat to 170°C, shear at 5000 rpm for 50 minutes; finally add 1%-2% of the asphalt mass of the plasticizer, stir for 25-35 minutes, and the high-elasticity modified asphalt is obtained.

2. The non-full-thickness cement pavement overlay material according to claim 1, characterized in that, The organic solvent is one or more of toluene, methanol, and castor oil.

3. The non-full-thickness cement pavement overlay material according to claim 1, characterized in that, The elasticizer is one or more of SBS, SEBS, and SIS; the plasticizer is one or two of dibutyl phthalate and dioctyl phthalate.

4. A construction process for a non-full-thickness cement pavement overlay material according to any one of claims 1-3, characterized in that, The method comprises the following steps: performing fine milling treatment on the cement pavement to form grooves on the road surface; uniformly spraying interlayer high-strength adhesive on the whole pavement, and the spraying amount is 0.3-0.5 kg / m 2 Finally, the non-full-thickness cement pavement overlay material is spread on the interlayer high-strength adhesive as a stress absorption layer.

5. The construction process of the non-full-thickness cement pavement overlay material according to claim 4, characterized in that, This also includes constructing a 4-5cm thick wearing course on top of the overlay material after the construction of the non-full-thickness cement pavement.

6. The construction process of the non-full-thickness cement pavement overlay material according to claim 5, characterized in that, The groove depth is 1.2~1.7mm, and the interlayer high-strength adhesive is prepared by shearing and stirring at 70°C for 1h with hydrogenated C9 resin with a molecular weight of 1000~2000, SIS with a molecular weight of 150,000~200,000, matrix asphalt, and xylene in a ratio of 11:4:33:

52.

7. The construction process of the non-full-thickness cement pavement overlay material according to claim 6, characterized in that, The wear layer is composed of 10-15mm basalt, 5-10mm basalt, 0-5mm basalt, mineral powder, polyester fiber, and SBS modified asphalt in a mass ratio of 40:22:29:9:0.2:6.2.

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