Preparation method of emulsified asphalt cold recycled mixture prefabricated part

Abstract

The invention discloses a preparation method of an emulsified asphalt cold recycled mixture prefabricated part, and belongs to the field of municipal engineering and highway engineering construction. According to the specific scheme, the method comprises the following steps: step 1, uniformly stirring and mixing 93.0-96.6 parts of asphalt mixture reclaimed materials, 0-2 parts of diffusion components and 0.5-1.5 parts of cement to obtain a mixture A; 2, uniformly stirring and mixing 2.9-4.7 parts of emulsified asphalt, water and the mixture A to obtain a mixture B; 3, the mixture B is poured into a prefabricated part mold, and compaction is conducted through a high-pressure static pressure or high-frequency vibration compaction method; and 4, after compaction, mold removal is conducted immediately, and a test piece obtained after mold removal is cured at the normal temperature for the specified age, so that the emulsified asphalt cold recycled mixture prefabricated part is obtained. According to the prefabricated part prepared by the method, asphalt mixture recycled waste materials are fully recycled, and the prefabricated part has the characteristics of low cost, convenience in production and processing, ecological environmental protection and good mechanical and corrosion-resistant properties.

Description

Technical Field

[0001] The invention belongs to the field of municipal engineering and highway engineering construction, and specifically relates to a method for preparing an emulsified asphalt cold recycled mixture prefabricated component. Background Art

[0002] With the gradual improvement of the current highway network, my country's road infrastructure development has gradually transitioned from the period of "mainly focusing on construction" to a new development stage of "equal emphasis on construction and maintenance" and "mainly focusing on maintenance". The waste of land resources and environmental pollution caused by the accumulation of recycled asphalt mixture (RAP) generated during asphalt pavement maintenance have become serious environmental problems. How to recycle and reuse RAP has become a key technical problem in the current road construction field. Asphalt pavement regeneration technology can not only absorb RAP well, but also reduce the consumption of non-renewable resources such as asphalt and stone.

[0003] Recycled asphalt prefabricated components have received widespread attention as a recycling solution. Recycled asphalt mixtures have good resistance to salt corrosion and water damage, and are particularly suitable for highways and ordinary roads in seasonally frozen areas. In these areas, highway curbs, slope protection structures and drainage ditches are often damaged by rainwater, snow melting agents, etc., affecting drainage and use functions. Recycled asphalt prefabricated components not only improve the poor durability of traditional cement materials, but also greatly increase the recycling rate of old asphalt materials, broadening the application field of recycling technology.

[0004] At present, most of the research on recycled asphalt mixture prefabricated components relies on the modification effect of modifiers such as SBS, polymer fibers, and plastics, and uses thermal regeneration to achieve fluidity and performance improvement. The Chinese invention patents with publication numbers CN113998923A and CN117645432A respectively disclose two prefabricated components and preparation methods that achieve 100% utilization of road milling materials. The developed prefabricated components have good mechanical properties, water resistance and erosion resistance, but the defects of these solutions include: 1) Both solutions require the addition of modifiers, and both require heating to ensure the fluidity of the materials and the uniform mixing of different materials; 2) The solution of CN113998923A requires the preparation of an emulsified asphalt slurry seal to ensure the water resistance and mechanical properties of the prefabricated components; 3) The proportion of mineral admixtures in CN117645432A is relatively high, reaching 8% to 12%. These defects lead to the high cost of prefabricated components and excessive mechanical properties in non-load-bearing application scenarios.

[0005] Compared with hot recycling technology, cold recycling technology does not require heating and insulation during the production and transportation of the mixture, which can not only adapt to the low-temperature production environment and reduce harmful gas emissions, but also has unique advantages in energy conservation and emission reduction. Compared with traditional cement-based prefabricated blocks, emulsified asphalt has strong chemical stability, is not easy to react chemically with salt, and the molded blocks have low modulus and good toughness. Therefore, the prefabricated blocks provided by the present invention are environmentally durable and have a longer service life. Studies have shown that the full life cycle energy consumption and carbon emissions of cold recycling technology can be reduced by 56.4% and 49.7% respectively compared with hot recycling technology. However, since the strength formation of cold recycled mixtures depends on the evaporation of water, and the molding of prefabricated components has high requirements for the integrity of the early mixture, there are few reports on cold recycled prefabricated components in current research. Summary of the invention

[0006] The present invention aims to utilize the low-carbon and environmentally friendly advantages of cold recycling technology to provide a method for preparing a prefabricated component of an emulsified asphalt cold recycled mixture that has good salt corrosion resistance and water damage resistance of asphalt mixture and does not rely on high-volume mineral admixtures. The prepared prefabricated components can be used for municipal and highway construction, for the construction of ancillary facilities such as side ditches and shoulders, and for paving pavement structures such as pedestrian walkways and driving lanes.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing an emulsified asphalt cold recycled mixture prefabricated component comprises the following steps:

[0009] Step 1: 93.0-96.6 parts of asphalt mixture recycled material, 0-2 parts of diffusion component and 0.5-1.5 parts of cement are put into a mixer and stirred for 30-50 seconds to mix them evenly to obtain mixture A;

[0010] Step 2: Add 2.9-4.7 parts of emulsified asphalt and water into a mixer and mix with mixture A, and stir for 30-50 seconds to obtain mixture B;

[0011] Step 3: Pour mixture B into the prefabricated component mold at one time. The mold size can be prepared according to the size of the building block, and compact it by high-pressure static pressure or high-frequency vibration compaction;

[0012] Step 4: demolding is performed immediately after compaction, and the demolded specimens are cured at room temperature for a specified age to obtain emulsified asphalt cold recycled mixture prefabricated components.

[0013] In step 1, the diffusion component is a light petroleum product, which includes one or more of kerosene, diesel, and gasoline.

[0014] In step one, the recycled asphalt mixture is divided into two or more grades through screening and used in grades to meet the requirements for the grading of emulsified asphalt recycled mixture in the "Technical Specifications for Highway Asphalt Pavement Regeneration" JTG / T 5521-2019.

[0015] In step 2, the emulsified asphalt uses modified emulsified asphalt, and the modifier used for modification includes one or more of water-based epoxy resin, liquid SBS, polyurethane, isocyanate, and SBR.

[0016] In step three, the vibration frequency of the high-frequency vibration compaction is greater than or equal to 5000 times / min, and the amplitude is greater than or equal to 15 mm.

[0017] In step three, the pressure of the high-pressure static pressure is greater than or equal to 250 MPa, and the static pressure time is greater than or equal to 5 s.

[0018] In step 2, the water content is determined based on the optimal moisture content determined by the compaction test and the moisture content of the recycled asphalt mixture.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The emulsified asphalt cold recycled mixture prefabricated components prepared by the present invention achieve 100% utilization of RAP, and the whole process does not require heating. It adopts the preparation method of high-pressure static pressure or high-frequency vibration, and can achieve immediate demoulding without relying on the addition of a large amount of mineral admixtures. Compared with cement-based prefabricated components, the prefabricated components provided by the present invention significantly improve the salt corrosion resistance and water damage resistance of the prefabricated components. Compared with hot-recycled asphalt mixture prefabricated components, since the production process does not require heating, it has the advantages of environmental protection and simple production and processing. The prefabricated components prepared by this method fully recycle the waste materials of asphalt mixture recycling materials, and have the characteristics of low cost, convenient production and processing, and ecological and environmental protection. At the same time, they have good mechanical properties and corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 : Precast components prepared with unscreened RAP after demoulding;

[0022] Figure 2 : Precast components prepared with screened RAP after demoulding; DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] The following examples and comparative examples are used to test the beneficial effects of the present invention:

[0025] Embodiment 1:

[0026] This embodiment provides a method for preparing a prefabricated component of an emulsified asphalt cold recycled mixture, which is carried out according to the following steps:

[0027] 1. Weigh 95 parts of recycled asphalt mixture, 4.5 parts of emulsified asphalt (determined according to the solid content of emulsified asphalt), 0.5 parts of cement, and appropriate amount of water (determined according to the optimal moisture content determined by the compaction test and the moisture content of recycled asphalt mixture) by mass.

[0028] 2. Put the recycled asphalt mixture and cement weighed in step 1 into a mixer and stir for 30-50 seconds to make them evenly mixed;

[0029] 3. Put the emulsified asphalt and water weighed in step 1 into the mixer and continue stirring for 30-50 seconds until they are fully mixed;

[0030] 4. Pour the cold recycled mixture obtained in step 3 into the mold of the prefabricated block at one time, and compact it by vibration compaction, with a vibration frequency of 5000 times / minute and an amplitude of 15mm;

[0031] 5. The test piece obtained in step 4 is demolded immediately, and the demolded test piece is cured at room temperature for 7 days to obtain an emulsified asphalt cold recycled mixture prefabricated component.

[0032] Embodiment 2:

[0033] This embodiment provides a method for preparing prefabricated components of emulsified asphalt cold recycled mixture, which differs from Embodiment 1 in that: in step 2, 2 portions of diffusion components are added, and the diffusion components are kerosene, and the rest are the same as Embodiment 1.

[0034] Embodiment 3:

[0035] This embodiment provides a method for preparing prefabricated components of emulsified asphalt cold recycled mixture, which differs from Embodiment 1 in that: the recycled asphalt mixture is screened at 4.75 and divided into two grades, including 60 parts of 0-5mm components and 40 parts of 5-25mm components, which are added to the mixer in sequence, and the rest are the same as Embodiment 1.

[0036] The emulsified asphalt cold recycled mixture prefabricated components prepared in Example 1 and Example 3 were immediately demoulded. Figure 1 and Figure 2 As shown, it can maintain good integrity and has good strength and good resistance to salt corrosion and water damage after maintenance.

[0037] Embodiment 4:

[0038] This embodiment provides a method for preparing prefabricated components of emulsified asphalt cold recycled mixture, which differs from Embodiment 2 in that the emulsified asphalt uses SBS modified emulsified asphalt, and the rest is the same as Embodiment 2.

[0039] Embodiment 5:

[0040] This embodiment provides a method for preparing emulsified asphalt cold recycled mixture prefabricated components, which differs from Embodiment 3 in that the emulsified asphalt adopts water-based epoxy-SBS composite modified emulsified asphalt, and the rest is the same as Embodiment 3.

[0041] Comparative Example 1:

[0042] Example 1 of a regenerated asphalt concrete prefabricated component and a preparation method disclosed in CN 117645432A.

[0043] With reference to industry standards, the road performance of the recycled asphalt concrete prefabricated components in each embodiment and comparative example was tested, and the test results are shown in the following table:

[0044] Table 1

[0045]

[0046] As can be seen from the above, although the compressive strength of the emulsified asphalt cold recycled mixture prefabricated component prepared by the present invention is lower than that of comparative example 1, it fully meets the requirements of prefabricated component C15. After curing, the prefabricated component has good strength and good resistance to salt corrosion and water damage. In addition, the preparation process of the present invention does not require heating, does not rely on the addition of a large amount of mineral admixtures, and can achieve immediate demoulding, which is low in cost and has good environmental benefits.

[0047] In specific implementation, those skilled in the art may further pre-treat the recycled asphalt mixture, including mechanical crushing and fine separation, adding regeneration agent, etc. In the present invention, the detailed operation of the pre-treatment of the recycled asphalt mixture is not particularly limited or described.

[0048] In specific implementation, those skilled in the art can combine the above-mentioned implementation schemes with common sense to obtain a preferred embodiment of the method for preparing prefabricated components of emulsified asphalt cold recycled mixture of the present invention.

[0049] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a prefabricated component of an emulsified asphalt cold recycled mixture, characterized in that: The following steps are involved: Step 1: 93.0-96.6 parts of asphalt mixture recycled material, 0-2 parts of diffusion component and 0.5-1.5 parts of cement are stirred and mixed to obtain mixture A; Step 2: Stir and mix 2.9 to 4.7 parts of emulsified asphalt, water and mixture A to obtain mixture B; Step 3: Pour the mixture B into the prefabricated component mold and compact it by high-pressure static pressure or high-frequency vibration compaction; Step 4: demolding is performed immediately after compaction, and the demolded specimens are cured at room temperature for a specified age to obtain emulsified asphalt cold recycled mixture prefabricated components.

2. The preparation method according to claim 1, characterized in that: In step 1, the diffusion component is a light petroleum product.

3. The preparation method according to claim 2, characterized in that: The light petroleum product includes one or more of kerosene, diesel and gasoline.

4. The preparation method according to claim 1, characterized in that: In step 1 and step 2, the stirring and mixing time is 30-50s.

5. The preparation method according to claim 1, characterized in that: In step one, the recycled asphalt mixture is divided into two or more grades through screening and used in grades to meet the requirements for the grading of emulsified asphalt recycled mixture in the "Technical Specifications for Highway Asphalt Pavement Regeneration" JTG / T 5521-2019.

6. The preparation method according to claim 1, characterized in that: In step 2, the emulsified asphalt uses modified emulsified asphalt, and the modifier used for modification includes one or more of water-based epoxy resin, liquid SBS, polyurethane, isocyanate, and SBR.

7. The preparation method according to claim 1, characterized in that: In step three, the vibration frequency of the high-frequency vibration compaction is greater than or equal to 5000 times / min, and the amplitude is greater than or equal to 15 mm.

8. The preparation method according to claim 1, characterized in that: In step three, the pressure of the high-pressure static pressure is greater than or equal to 250 MPa, and the static pressure time is greater than or equal to 5 s.

9. The preparation method according to claim 1, characterized in that: In step 2, the water content is determined based on the optimal moisture content determined by the compaction test and the moisture content of the recycled asphalt mixture.

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