Recycled aggregate high-toughness cement stabilizing material for road base and preparation method of recycled aggregate high-toughness cement stabilizing material

Abstract

The invention discloses a recycled aggregate high-toughness cement stabilizing material for a road base and a preparation method of the recycled aggregate high-toughness cement stabilizing material, and belongs to the technical field of road engineering materials. The material is prepared from the following components in parts by weight: 40 to 50 parts of recycled coarse aggregate, 20 to 30 parts of recycled fine aggregate, 4 to 6 parts of cement, 3 to 5 parts of mineral powder, 2 to 4 parts of metakaolin, 1 to 2 parts of polymer emulsion, 0.1 to 0.3 part of polypropylene fiber, 0.2 to 0.4 part of water reducing agent and 6 to 8 parts of water. The preparation method comprises the following steps: uniformly mixing the dry materials, uniformly mixing the polymer emulsion, the water reducing agent and the water in a container, adding the mixture into the dry materials, stirring, and finally adding the fibers and uniformly dispersing. Through the synergistic toughening effect of the polymer emulsion and the fibers and the micro-aggregate filling effect of the mineral admixture, the crack resistance, toughness and durability of the recycled aggregate road material are remarkably improved, high-added-value resource utilization of the construction waste is achieved, and the recycled aggregate road material is suitable for all levels of road bases and has the advantages of being low in cost, environmentally friendly and excellent in performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of road engineering materials, in particular to a high-toughness cement stabilized material prepared from construction waste recycled aggregate and a preparation method thereof, which is suitable for road base construction. BACKGROUND

[0002] With the continuous advancement of urbanization in China, a large amount of construction waste is generated in old city reconstruction and infrastructure construction, of which about 30%-40% is waste concrete and bricks. The traditional disposal method of these construction wastes is mainly landfill and stacking, which not only occupies a large amount of land resources, but also pollutes the soil and water. Crushing and screening the construction waste into recycled aggregate and using it in road engineering is one of the effective ways to realize its resource utilization. At present, cement stabilized gravel material is widely used in road base, and its aggregate is mainly derived from natural stone. Large-scale mining of natural stone will cause problems such as mountain destruction and deterioration of ecological environment. Using recycled aggregate to partially or completely replace natural aggregate can effectively alleviate resource pressure and reduce engineering cost, which has significant environmental and economic benefits. However, recycled aggregate has inherent defects such as high porosity, high water absorption, low strength and large crushing value due to the attachment of old cement mortar on its surface, which leads to large dry shrinkage, high brittleness and easy cracking of the cement stabilized material prepared therefrom, seriously affecting the long-term service performance and service life of the road base, which greatly limits the large-scale application of recycled aggregate in high-grade roads. Therefore, it has become a technical problem to be solved in the field to develop a road base material that can not only absorb a large amount of recycled aggregate, but also has high crack resistance and excellent road performance. SUMMARY

[0003] The present application aims to overcome the shortcomings of the prior art and provide a recycled aggregate high-toughness cement stabilized material for road base and a preparation method thereof. The material significantly improves the toughness and anti-dry-shrinkage-cracking performance of the recycled aggregate cement stabilized material through composite modification technology, realizes efficient resource utilization of construction waste under the premise of ensuring mechanical strength.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0005] A recycled aggregate high-toughness cement stabilized material for road base, in terms of weight parts, comprises the following raw materials: recycled coarse aggregate (5-20mm): 40-50 parts; recycled fine aggregate (0-5mm): 20-30 parts; cement: 4-6 parts; mineral powder: 3-5 parts; metakaolin: 2-4 parts; polymer emulsion (solid content ≥40%): 1-2 parts; polypropylene fiber: 0.1-0.3 parts; water reducing agent: 0.2-0.4 parts; water: 6-8 parts.

[0006] Preferably, the recycled aggregate is derived from construction waste concrete, and meets the technical requirements of a crushing value of ≤20% and a water absorption rate of ≤8%; the polymer emulsion is a styrene-acrylic emulsion or an acrylate emulsion, which forms a polymer film after molding, wraps the aggregate and cement hydration products, and plays a role of toughening, enhancing adhesion and blocking cracks; the polypropylene fiber has a length of 6-12 mm and is subjected to hydrophilic surface treatment, so as to improve the dispersibility of the fiber in the slurry and the adhesion of the fiber to the matrix, and play a secondary strengthening and blocking effect; and the water reducing agent is a polycarboxylic acid-based high-performance water reducing agent, which is used to reduce the water consumption and improve the material density.

[0007] The application also provides a preparation method of the material, comprising the following steps:

[0008] S1. Recycled coarse aggregate, recycled fine aggregate, cement, mineral powder and metakaolin are weighed according to the proportion, and are put into a mixer for dry mixing for 1-2 minutes until they are uniformly mixed;

[0009] S2. The polymer emulsion, the water reducing agent and water are mixed in a container and are stirred uniformly;

[0010] S3. The solution obtained in S2 is slowly added to the dry materials in S1 while the mixer is kept stirring, and the stirring is continued for 2-3 minutes, so that the mixture is uniformly mixed;

[0011] S4. Polypropylene fibers are added to the mixer, and the stirring is continued for 1-2 minutes, so that the fibers are uniformly dispersed in the mixture without agglomeration;

[0012] S5. The mixture is discharged and can be used for on-site paving and compaction.

[0013] Compared with the prior art, the application has the following beneficial effects:

[0014] (1) The unity of high performance and resource regeneration is realized: the material meets the requirements of mechanical strength and durability of high-grade road base, realizes the bulk and high-value utilization of construction waste recycled aggregate, and has excellent engineering performance and remarkable environmental and economic benefits.

[0015] (2) The crack resistance and long-term durability are significantly improved: the material as a whole has extremely low dry shrinkage stress and excellent crack resistance, can effectively inhibit the generation and development of base cracks, and has excellent resistance to freeze-thaw and environmental erosion, thereby ensuring the long-term stable service of the road.

[0016] (3) The material has excellent construction ease of use and economy: the mixture has good workability, is easy to be paved and compacted on site, has high construction efficiency, and has low raw material cost and wide sources, and is very suitable for large-scale application in road base engineering of all levels.

[0017] (4) Promote green construction and sustainable development: the popularization and application of the technology can significantly reduce the consumption of natural mineral resources in engineering construction and reduce the land occupation and environmental pollution caused by construction waste disposal. DETAILED DESCRIPTION

[0018] The application will be further described in conjunction with specific embodiments, but the application is not limited to these embodiments.

[0019] Example 1

[0020] A recycled aggregate high-toughness cement stabilized material for road base comprises, by weight fraction, the following components: recycled coarse aggregate (5-20mm): 45 parts; recycled fine aggregate (0-5mm): 25 parts; P.O 42.5 cement: 5 parts; S95 grade mineral powder: 4 parts; metakaolin: 3 parts; benzene-polymer emulsion (solid content 48%): 1.5 parts; polypropylene fiber (12mm, hydrophilic treatment): 0.2 parts; polycarboxylic acid water reducing agent: 0.3 parts; water: 7 parts. The recycled aggregate is derived from construction waste concrete and needs to meet the technical requirements of crushing value ≤20% and water absorption rate ≤8%; the polymer emulsion is benzene-polymer emulsion or acrylate emulsion, which forms a polymer film after molding, wrapping the aggregate and cement hydration products, playing the role of toughening, enhancing bonding and crack resistance; the polypropylene fiber has a length of 6-12mm and is subjected to hydrophilic surface treatment to improve its dispersibility in the slurry and adhesion to the matrix, playing the role of secondary strengthening and crack resistance; the water reducing agent is a polycarboxylic acid high-performance water reducing agent, which is used to reduce the water consumption and improve the material density.

[0021] A preparation method of a recycled aggregate high-toughness cement stabilized material for road base is as follows:

[0022] S1Pour the recycled coarse and fine aggregate, cement, mineral powder and metakaolin into a mixer and dry mix for 90 seconds;

[0023] S2Mix the benzene-polymer emulsion, water reducing agent and water uniformly in another container;

[0024] S3Slowly pour the above-mentioned mixed solution into the dry materials in the running state of the mixer and stir for 150 seconds;

[0025] S4Add polypropylene fiber and continue to stir for 120 seconds and discharge;

[0026] S5Prepare test pieces according to the Highway Engineering Inorganic Binder Stabilized Material Test Specification (JTG E51-2009), maintain them under standard conditions and test their performance.

[0027] Example 2

[0028] A recycled aggregate high-toughness cement stabilized material for road base, comprising the following components in parts by weight: recycled coarse aggregate (5-20 mm): 40 parts; recycled fine aggregate (0-5 mm): 30 parts; P.O 42.5 cement: 6 parts; S95 grade mineral powder: 3 parts; metakaolin: 4 parts; benzene propylene emulsion (solid content 48%): 2 parts; polypropylene fiber (12 mm, hydrophilic treatment): 0.3 parts; polycarboxylic acid water reducing agent: 0.4 parts; water: 8 parts. The recycled aggregate is derived from construction waste concrete and needs to meet the technical requirements of crushing value ≤20% and water absorption rate ≤8%; the polymer emulsion is benzene propylene emulsion or acrylate emulsion, which forms a polymer film after molding, wrapping the aggregate and cement hydration products, playing the role of toughening, enhancing bonding and blocking; the polypropylene fiber has a length of 6-12 mm and is subjected to hydrophilic surface treatment to improve its dispersibility in the slurry and the bonding force with the matrix, playing the role of secondary strengthening and blocking; the water reducing agent is a polycarboxylic acid high-performance water reducing agent, which is used to reduce the water consumption and improve the material density.

[0029] A preparation method of a recycled aggregate high-toughness cement stabilized material for road base is as follows:

[0030] S1 pour the recycled coarse and fine aggregate, cement, mineral powder and metakaolin into a mixer and dry mix for 90 seconds;

[0031] S2 mix the benzene propylene emulsion, water reducing agent and water in another container uniformly;

[0032] S3 slowly pour the mixed solution into the dry materials in the running state of the mixer and stir for 150 seconds;

[0033] S4 add the polypropylene fiber and continue to stir for 120 seconds and discharge;

[0034] S5 prepare test pieces according to the Highway Engineering Inorganic Binder Stabilized Material Test Code (JTG E51-2009), maintain under standard conditions and perform performance testing.

[0035] Example 3

[0036] A recycled aggregate high toughness cement stabilized material for road base, comprising the following components in parts by weight: recycled coarse aggregate (5-20mm): 50 parts; recycled fine aggregate (0-5mm): 20 parts; P.O 42.5 cement: 4 parts; S95 grade mineral powder: 5 parts; metakaolin: 2 parts; styrene-acrylic emulsion (solid content 48%): 1 part; polypropylene fiber (12mm, hydrophilic treatment): 0.1 part; polycarboxylic acid water reducing agent: 0.2 parts; water: 6 parts. The recycled aggregate is derived from construction waste concrete, and needs to meet the technical requirements of crushing value ≤20% and water absorption ≤8%; the polymer emulsion is a styrene-acrylic emulsion or an acrylate emulsion, which forms a polymer film after molding, wrapping the aggregate and cement hydration products, and plays a role in toughening, enhancing adhesion and crack resistance; the polypropylene fiber has a length of 6-12mm and is subjected to hydrophilic surface treatment to improve its dispersibility in the slurry and adhesion to the matrix, and plays a secondary strengthening and crack resistance effect; the water reducing agent is a polycarboxylic acid high-performance water reducing agent, which is used to reduce the water consumption and improve the material density.

[0037] A preparation method of a recycled aggregate high toughness cement stabilized material for road base is as follows:

[0038] S1 pour the recycled coarse and fine aggregate, cement, mineral powder and metakaolin into a mixer and dry mix for 90 seconds;

[0039] S2 mix the styrene-acrylic emulsion, water reducing agent and water in another container uniformly;

[0040] S3 slowly pour the above-mentioned mixed solution into the dry materials in the running state of the mixer, and stir for 150 seconds;

[0041] S4 add the polypropylene fiber, continue to stir for 120 seconds, and discharge;

[0042] S5 prepare test pieces according to the "Highway Engineering Inorganic Binder Stabilized Material Test Code" (JTG E51-2009), maintain under standard conditions, and perform performance testing.

[0043] Performance testing:

[0044] In order to evaluate the performance of the material, the unconfined compressive strength and splitting strength of the above-mentioned three different mix proportions are evaluated, as shown in Table 1.

[0045] Table 1 Strength performance evaluation table

[0046]

[0047] From the performance test results above, it can be seen that: (1) the recycled aggregate high toughness cement stabilized material prepared by the application can meet the specification requirements of high-grade road base material through the unconfined compressive strength and splitting strength experiments. (2) The cement stabilized material prepared by the application can significantly reduce the raw material cost and improve the resource utilization rate of solid waste under the premise of ensuring the road performance, and can absorb a large amount of construction waste recycled aggregate. (3) The cement stabilized material prepared by the application can significantly improve the anti-drying shrinkage cracking performance and durability of the material through the composite toughening effect of polymer emulsion and polypropylene fiber, and can still maintain good structural integrity after freeze-thaw cycle.

[0048] Therefore, the application adopts the above-mentioned recycled aggregate high toughness cement stabilized material for road base, which is prepared by mixing recycled aggregate, cement, mineral powder, metakaolin, polymer emulsion, polypropylene fiber, water reducing agent and water in a certain proportion. The material can significantly improve the crack resistance, toughness, durability and volume stability of the material when applied to the road base, and can realize the bulk and high-value utilization of construction waste, which has significant environmental, economic and social benefits.

[0049] In the description of the present specification, the description of referring to the terms "one experimental example", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in conjunction with the experimental example or example are included in at least one experimental example or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same experimental example or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more experimental examples or examples in a suitable manner.

[0050] Finally, it should be pointed out that: the above experimental examples are only used to illustrate the technical solutions of the present application but not to limit it, although the present application has been described in detail with reference to the preferred experimental examples, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A recycled aggregate high-ductility cement stabilized material for road base, characterized by, The raw materials include, in parts by weight, recycled coarse aggregate (5-20mm): 40-50 parts; recycled fine aggregate (0-5mm): 20-30 parts; cement: 4-6 parts; mineral powder: 3-5 parts; metakaolin: 2-4 parts; polymer emulsion (solid content ≥40%): 1-2 parts; polypropylene fiber: 0.1-0.3 parts; water reducing agent: 0.2-0.4 parts; and water: 6-8 parts. The recycled coarse aggregate and the recycled fine aggregate are derived from construction waste concrete, have a crushing value of not more than 20%, and a water absorption rate of not more than 8%.

2. A recycled aggregate high ductility cement stabilized material for road base according to claim 1, characterized in that, The polypropylene fiber has a length of 6-12mm and is subjected to hydrophilic surface treatment.

3. The recycled aggregate high ductility cement stabilized material for road base according to claim 1, characterized in that, The polymer emulsion is a styrene-acrylic emulsion or an acrylate emulsion.

4. The recycled aggregate high ductility cement stabilized material for road base according to claim 1, characterized in that, The water reducing agent is a polycarboxylic acid-based high-performance water reducing agent.

5. The recycled aggregate high ductility cement stabilized material for road base according to claim 1, characterized in that, The method comprises the following steps:

6. A method of producing a recycled aggregate high ductility cement stabilized material as claimed in any one of claims 1 to 5, characterized in that, S1. The recycled coarse aggregate, the recycled fine aggregate, the cement, the mineral powder, and the metakaolin are put into a mixer and dry-mixed for 1-2 minutes to obtain a mixture; S2. The polymer emulsion, the water reducing agent, and water are mixed and stirred uniformly; S3. The mixture solution is slowly added to the dry mixture of step S1 under stirring, and stirred for 2-3 minutes to obtain a mixture; S4. The polypropylene fiber is added, and the mixture is continuously stirred for 1-2 minutes until the fiber is uniformly dispersed in the mixture; S5. The recycled aggregate high-toughness cement stabilized material is obtained. The material is used for paving and compacting of a road base, and the performance test method is performed according to the “Highway Engineering Inorganic Binder Stabilized Material Test Specification” (JTG E51-2009).

7. The method of claim 6, wherein, The material has a 7d unconfined compressive strength of not less than 3.0MPa, a 28d unconfined compressive strength of not less than 4.5MPa, and a 28d splitting strength of not less than 0.6MPa.

8. The material of claim 1, wherein, ​

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