Method for preparing road base material by using construction waste recycled aggregate

Abstract

The invention relates to the technical field of building materials, in particular to a preparation method of a road base material using construction waste recycled aggregate. Comprising the steps of raw material pretreatment, raw material fine treatment, sorting, high-speed grinding and solidification mixing. According to the method, high-value utilization of urban solid waste such as waste incineration fly ash, engineering muck and decoration waste can be greatly promoted; and meanwhile, the pressure of raw material shortage in road engineering construction can be effectively relieved, a foundation is laid for sustainable development of the traffic industry, the aggregate angularity can be improved, the interlocking force and the shear strength can be improved, strengthening liquid soaking is chemical strengthening, microcracks can be repaired, the water absorption rate can be reduced, and the water damage risk can be reduced.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a method for preparing road base materials using recycled aggregates from construction waste. Background Technology

[0002] The road base course is a layered structure constructed on the surface of the subgrade (or subbase) using a single material laid in layers according to specific technical measures. The quality of its materials directly affects the quality and performance of the road surface. The base course is the load-bearing layer of the entire road and plays a role in stabilizing the road surface. Road base courses are divided into inorganic binder stabilized base courses and crushed / gravel base courses.

[0003] Construction waste is a general term encompassing engineering spoil, engineering mud, construction waste, demolition waste, and renovation waste. It includes waste soil, materials, and other waste generated during the construction, expansion, renovation, and demolition of various buildings, structures, and pipelines, as well as during residential home decoration and renovation. It does not include construction waste that has been inspected and identified as hazardous waste.

[0004] Currently, the main materials used in the base course of highways in my country are crushed stone, gravel, and slag. The over-exploitation and extraction of these materials have had a significant impact on the environment and are leading to the depletion of limited natural resources. In the construction sector, with the rapid development of urban construction, the amount of construction waste is increasing daily. Statistics show that my country produces 40 to 50 million tons of urban construction waste annually, the main components of which are waste bricks, mortar, and concrete.

[0005] Construction waste has poor mechanical properties, and regulations in the highway engineering industry stipulate that construction waste cannot be directly used as road filler. Since construction waste is non-combustible, it is disposed of by means of landfill and stockpiling. These disposal methods require a large amount of land and consume a lot of disposal funds, and also pollute the environment.

[0006] Because the performance of recycled aggregates from construction waste is lower than that of natural crushed stone, and the quality of recycled products is difficult to guarantee, the specific application of construction waste in road base materials requires extensive exploration to meet the performance requirements of these materials. Furthermore, to increase the scale of resource utilization, in addition to conventional construction waste, other waste materials are often added to road base materials. When these other waste materials have low performance and are toxic, they further reduce the performance of the road base materials and introduce toxicity, making them unsuitable for direct use in highways.

[0007] To address the aforementioned problems associated with construction waste, this invention provides a method for preparing road base materials using recycled aggregates from construction waste. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing road base material using recycled aggregate from construction waste, so as to solve the problems mentioned in the background art.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing road base material using recycled aggregate from construction waste, comprising the following steps:

[0010] S1, raw material pretreatment: collect construction waste raw materials, manually sort and remove impurities, put the raw materials into a jaw crusher, crush them to obtain pretreated raw materials, the average diameter of the pretreated raw materials is less than 350mm;

[0011] S2, raw material fine processing, the pre-treated raw materials are crushed a second time using a cone crusher to obtain secondary processed materials with an average diameter of less than 40mm. The secondary processed materials are then fed into a multi-stage linkage equipment to remove residual metals, light materials and mud powder to obtain finely processed aggregates.

[0012] S3, the obtained finely processed aggregate is fed into the separator and divided into primary aggregate, secondary aggregate and tertiary aggregate according to the particle size. The oversized finely processed aggregate is returned to the cone crusher for secondary crushing.

[0013] S4, take a quantitative mixture of silica hydrochloric acid solution, organosilicon hydrophobic agent and boric acid, and react at 80℃ for 3 hours to form a curing agent;

[0014] S5, three grades of aggregate are fed into a vertical crusher for high-speed grinding, and then soaked in a strengthening liquid for 24 hours to obtain solidified aggregate;

[0015] S6. The cured aggregate and curing agent are mixed in a ratio of 35:1 to 12:1 to obtain the finished road base material.

[0016] In a more optimized manner, in step S2, the multi-stage linkage equipment includes a magnetic separator for removing residual metals, an air separator for separating light materials, and a desliming screen for removing mud powder.

[0017] In a more optimized manner, the lightweight materials include plastics and wood chips; the average particle size of the mud powder shown is less than 1 mm; and the impurity content of the refined aggregate is less than 1% after being processed by a multi-stage linkage equipment.

[0018] Ideally, the average particle size of the primary aggregate is 0–5 mm, the average particle size of the secondary aggregate is 6–16 mm, and the average particle size of the tertiary aggregate is 17–32 mm.

[0019] Ideally, the reinforcing solution is an epoxy emulsion or an acetic acid solution, with the epoxy emulsion having a solid content of 10-15% and the acetic acid solution having a concentration of ≥80%.

[0020] Ideally, during high-speed grinding, the grinding rate should exceed 2200 r / min. Ideally, the step...

[0021] In step S6, the mass ratio of cured aggregate to curing agent is 24:1.

[0022] Ideally, the water absorption rate of the finished road base material should be less than 5%, and the crushing value should be less than 15%.

[0023] Ideally, the compaction degree of the finished road base material should be greater than 96% during construction.

[0024] In a more optimized manner, during step S6, a silane coupling agent and nanocellulose can also be added during mixing to obtain the finished product.

[0025] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0026] (1) This invention can remove foreign objects such as steel bars, wood, and plastics, avoiding damage to subsequent equipment and impurities mixed into the aggregate; by crushing large pieces of construction waste to less than 400mm by a jaw crusher, conditions can be created for fine crushing; magnetic separation can remove residual metal (such as steel bars) and prevent the base material from expanding and cracking due to metal corrosion; air separation can separate light materials such as wood chips and plastics and improve the density of aggregates; mud removal screen can remove mud powder less than 1mm, reduce water absorption rate and enhance the frost resistance of the base.

[0027] (2) In this invention, high-speed grinding is mechanical activation, which can increase the angularity of aggregate, improve the interlocking force and shear strength, while immersion in strengthening liquid is chemical strengthening, which can repair micro-cracks, reduce water absorption rate and reduce the risk of water damage.

[0028] (3) In this invention, the addition of curing agent can provide a gelling effect, enhance the overall strength and stability, improve the interfacial adhesion of aggregate, improve durability, and ensure compaction uniformity; in addition, the addition of silane coupling agent (0.5-1%) can enhance the bonding strength between epoxy resin and aggregate, and the addition of nanocellulose can optimize the interface structure of recycled aggregate-matrix and reduce the porosity by more than 30%.

[0029] (4) This invention can greatly promote the high-value utilization of urban solid waste such as fly ash from waste incineration, construction waste, and decoration waste; at the same time, it can effectively alleviate the pressure of raw material shortage in road construction and lay the foundation for the sustainable development of the transportation industry. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] This invention provides a method for preparing road base material using recycled aggregate from construction waste, comprising the following steps:

[0032] S1, Raw Material Pretreatment: Collect construction waste raw materials, manually sort and remove impurities, and feed the raw materials into a jaw crusher for crushing to obtain pretreated raw materials with an average diameter of less than 350mm. This step can remove foreign objects such as steel bars, wood, and plastics, avoiding subsequent equipment damage and impurities from mixing into the aggregate; by coarsely crushing large pieces of construction waste to below 400mm using a jaw crusher, conditions are created for fine crushing.

[0033] S2, raw material fine processing: the pre-treated raw materials are crushed a second time using a cone crusher to obtain secondary processed materials with an average diameter of less than 40mm. The secondary processed materials are then fed into a multi-stage linkage device to remove residual metals, light materials and mud powder to obtain finely processed aggregates.

[0034] Impact crushers can crush materials to below 40mm in a secondary process, which can optimize the aggregate particle size distribution; magnetic separation can remove residual metal (such as steel bars) and prevent the base material from expanding and cracking due to metal corrosion; air separation can separate light materials such as wood chips and plastics, and improve the density of aggregates; and mud removal screens can remove mud powder below 1mm, reduce water absorption, and enhance the frost resistance of the base.

[0035] In this step, the multi-stage linkage equipment includes a magnetic separator for removing residual metals, an air separator for separating light materials, and a desliming screen for removing mud powder. Light materials include plastics and wood chips; the average particle size of the mud powder is less than 1 mm; after processing by the multi-stage linkage equipment, the impurity content of the refined aggregate is less than 1%.

[0036] In step S3, the refined aggregate is fed into a sorting machine and separated into primary, secondary, and tertiary aggregates according to particle size. Oversized refined aggregates are returned to a cone crusher for secondary crushing. In this step, the average particle size of the primary aggregate is 0–5 mm, the average particle size of the secondary aggregate is 6–16 mm, and the average particle size of the tertiary aggregate is 17–32 mm. Separating the aggregate into three grades ensures that the gradation meets road base specifications, improves raw material utilization, and reduces waste.

[0037] S4, take a quantitative mixture of silica hydrochloric acid solution, organosilicon hydrophobic agent and boric acid, and react at 80℃ for 3 hours to form a curing agent;

[0038] S5. The three grades of aggregate are fed into a vertical crusher for high-speed grinding. After grinding, they are soaked in a strengthening liquid for 24 hours to obtain solidified aggregate. The strengthening liquid in this step is either epoxy emulsion or acetic acid solution. The epoxy emulsion has a solid content of 10-15%, and the acetic acid solution has a concentration ≥80%. During high-speed grinding, the grinding rate is greater than 2200 r / min.

[0039] High-speed grinding is a mechanical activation process that increases the angularity of aggregates, enhances interlocking force and shear strength, while immersion in strengthening liquid is a chemical strengthening process that can repair micro-cracks, reduce water absorption, and minimize the risk of water damage.

[0040] S6. Mix the cured aggregate and curing agent in a ratio of 35:1 to 12:1, with the optimal ratio being 24:1. This yields the finished road base material. Silane coupling agents and nanocellulose can also be added during mixing to produce the final product. The resulting road base material has a water absorption rate of less than 5%, a crushing value of less than 15%, and a compaction degree greater than 96% during construction.

[0041] The addition of curing agents can provide a gelling effect, enhance the overall strength and stability, improve the interfacial adhesion of aggregates, improve durability, and ensure uniform compaction. In addition, the addition of silane coupling agents (0.5-1%) can enhance the bonding strength between epoxy resin and aggregates, and the addition of nanocellulose can optimize the interface structure of recycled aggregates and matrix, reducing porosity by more than 30%.

[0042] The present invention verifies the performance of the prepared road base material through several embodiments, as shown in Table 1, and the material properties are shown in Table 2.

[0043] Table 1. Additive content in each embodiment.

[0044] project Example 1 Example 2 Example 3 Example 4 Example 5 Epoxy emulsion solid content 13％ 10％ 15％ 13％ 13％ The ratio of solidified aggregate to solidifying agent content 24:1 24:1 24:1 35:1 12:1 Mixed silica hydrochloric acid solution content (wt%) 55 55 55 55 55 Organosilicon water-repellent content (wt%) 2 2 2 2 2 boric acid wt% 1.3 1.3 1.3 1.3 1.3

[0045] Table 2 Performance of the finished products obtained from each embodiment

[0046]

[0047] As can be seen from the data in Table 2, the performance of the road base materials prepared in each embodiment can meet the usage standards, and the road base material in Embodiment 1 has the best performance.

[0048] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing road base material using recycled aggregate from construction waste, characterized in that, Includes the following steps: S1, raw material pretreatment: collect construction waste raw materials, manually sort and remove impurities, put the raw materials into a jaw crusher, crush them to obtain pretreated raw materials, the average diameter of the pretreated raw materials is less than 350mm; S2, raw material fine processing, the pre-treated raw materials are crushed a second time using a cone crusher to obtain secondary processed materials with an average diameter of less than 40mm. The secondary processed materials are then fed into a multi-stage linkage equipment to remove residual metals, light materials and mud powder to obtain finely processed aggregates. S3, the obtained finely processed aggregate is fed into the separator and divided into primary aggregate, secondary aggregate and tertiary aggregate according to the particle size. The oversized finely processed aggregate is returned to the cone crusher for secondary crushing. S4, take a quantitative mixture of silica hydrochloric acid solution, organosilicon hydrophobic agent and boric acid, and react at 80℃ for 3 hours to form a curing agent; S5, three grades of aggregate are fed into a vertical crusher for high-speed grinding, and then soaked in a strengthening liquid for 24 hours to obtain solidified aggregate; S6. The cured aggregate and curing agent are mixed in a ratio of 35:1 to 12:1 to obtain the finished road base material.

2. The method for preparing road base material using recycled aggregate from construction waste according to claim 1, characterized in that: In step S2, the multi-stage linkage equipment includes a magnetic separator for removing residual metals, an air separator for separating light materials, and a mud screen for removing mud powder.

3. The method for preparing road base material using recycled aggregate from construction waste according to claim 2, characterized in that: The lightweight materials include plastics and wood chips; the average particle size of the mud powder shown is less than 1 mm; the impurity content of the refined aggregate is less than 1% after being processed by a multi-stage linkage equipment.

4. The method for preparing road base material using recycled aggregate from construction waste according to claim 1, characterized in that: The average particle size of the primary aggregate is 0-5 mm, the average particle size of the secondary aggregate is 6-16 mm, and the average particle size of the tertiary aggregate is 17-32 mm.

5. The method for preparing road base material using recycled aggregate from construction waste according to claim 1, characterized in that: The strengthening liquid is an epoxy emulsion or an acetic acid solution, wherein the epoxy emulsion has a solid content of 10-15% and the acetic acid solution has a concentration of ≥80%.

6. The method for preparing road base material using recycled aggregate from construction waste according to claim 1, characterized in that: During the high-speed grinding process, the grinding rate is greater than 2200 r / min.

7. The method for preparing road base material using recycled aggregate from construction waste according to claim 1, characterized in that: In step S6, the mass ratio of cured aggregate to curing agent is 24:

1.

8. The method for preparing road base material using recycled aggregate from construction waste according to claim 1, characterized in that: The finished road base material has a water absorption rate of less than 5% and a crushing value of less than 15%.

9. The method for preparing road base material using recycled aggregate from construction waste according to claim 1, characterized in that: The compaction degree of the finished road base material must be greater than 96% during construction.

10. The method for preparing road base material using recycled aggregate from construction waste according to claim 1, characterized in that: In step S6, silane coupling agent and nanocellulose can also be added during mixing to obtain the finished product.

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