A flexible concrete material suitable for assembled pavement and its preparation method and application

Abstract

The present invention discloses a flexible concrete material suitable for prefabricated pavement, a preparation method thereof, and an application thereof. The flexible concrete material is prepared from the following components, measured by weight: 435-460 parts of modified cement, 20-40 parts of fly ash, 0.3-0.5 parts of air entraining agent, 4-6 parts of water reducer, 1100-1200 parts of coarse aggregate, 540-560 parts of fine aggregate, 35-60 parts of modified rubber-fiber dispersion, and 190-230 parts of water. The concrete material can be used to prepare a flexible concrete prefabricated road slab that meets the requirements of transportation, lifting, and on-site assembly and has the characteristics of both asphalt concrete and cement concrete materials. The flexible concrete prefabricated road slab can effectively solve the problems of rutting on roads with complex traffic volume and the coordination of the allowable deformation of prefabricated prefabricated pavement and supporting foundation.

Description

Technical Field

[0001] The present invention relates to the field of concrete preparation, and in particular to a flexible concrete suitable for assembled pavement, a preparation method thereof, and an application thereof. Background Art

[0002] Traditional pavement projects typically use on-site pouring for cement pavement or continuous paving for asphalt pavement. However, traditional pavement construction suffers from low efficiency, long construction periods, high labor and equipment requirements, and significant disruption to residents near the construction site. Furthermore, subsequent maintenance is difficult to perform accurately and quickly, making it difficult to adapt to the development of smart roads. Prefabricated paving technology offers a promising solution.

[0003] However, traditional cement concrete materials have high rigidity, resulting in poor bending resistance for the resulting prefabricated concrete slabs. The inability to adapt to differential deformation of the roadbed significantly limits the promotion and application of prefabricated concrete pavements. Furthermore, while municipal roads are currently primarily asphalt-paved, due to traffic channelization, rutting is unavoidable at traffic lights, bus stops, and bus lanes after a period of use. This is due to the natural properties of asphalt pavement. Therefore, concrete is often used for paving these sections, but the junction of traditional concrete and asphalt pavements lacks aesthetic appeal, impacting the cityscape. Furthermore, these locations are prone to traffic congestion, and repairs and slab replacements can easily cause traffic jams, significantly impacting society.

[0004] Chinese patent document CN202011037700.X provides a wet-mix concrete specifically for prefabricated walls and a preparation method thereof, which is composed of the following raw materials in weight fractions: 50-80 parts of cement, 20-30 parts of crushed stone powder, 15-30 parts of crushed stone, 25-40 parts of fine sand, 5-10 parts of cement viscosity enhancer, 2-6 parts of cement viscosity reducer, 1-3 parts of sulfate, and 100-150 parts of water; however, the concrete has insufficient tensile strength and is prone to splitting.

[0005] Chinese patent document CN202211665846.8 discloses a lightweight, high-strength, and high-durability concrete for prefabricated buildings and a preparation method thereof. The components include cement, water, fine aggregate, light coarse aggregate, composite admixtures, water reducer, polyacrylonitrile fiber, and basalt fiber; however, the elastic modulus of the concrete is relatively high and the toughness is relatively low.

[0006] In view of this, there is an urgent need to propose a flexible concrete material with low elastic modulus, high toughness, and that meets the requirements of transportation, lifting and on-site assembly and has the characteristics of both asphalt concrete and cement concrete for use in prefabricated road panels, in order to solve the problems of rutting on pavement with complex traffic volume, and the coordination of allowable deformation of prefabricated assembled pavements and supporting foundations, thereby promoting the rapid development and large-scale application of prefabricated pavements. Summary of the Invention

[0007] In order to address the deficiencies in the prior art, the purpose of the present invention is to provide a flexible concrete material for prefabricated pavements, a preparation method and application thereof, and to prepare flexible concrete prefabricated road panels that meet the requirements of transportation, lifting and on-site assembly and have the properties of both asphalt concrete and cement concrete materials, which can effectively solve the problems of rutting on pavements with complex traffic volume, and the coordination of allowable deformation of prefabricated prefabricated pavements and supporting foundations.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A flexible concrete material suitable for prefabricated pavement is prepared from the following components, measured by weight: 435-460 parts of modified cement, 20-40 parts of fly ash, 0.3-0.5 parts of air entraining agent, 4-6 parts of water reducer, 1100-1200 parts of coarse aggregate, 540-560 parts of fine aggregate, 35-60 parts of modified rubber-fiber dispersion, and 190-230 parts of water.

[0010] Preferably, the fly ash has a fineness value of less than 13%, a water content of less than 1.0%, a SO3 volume fraction of less than 4.5%, and a water solubility of less than 98%.

[0011] Preferably, the coarse aggregate is a well-graded crushed stone with a particle size of 2 to 20 mm; the fine aggregate is machine-made sand with a fineness modulus of 3.0 to 3.6 and an apparent density of 2500 to 2700 kg / m 3 .

[0012] Preferably, the modified cement preparation method is: adding epoxy resin to cement and stirring evenly to obtain the modified cement; the volume ratio of epoxy resin to cement is 10-20:100.

[0013] Preferably, the preparation method of the modified rubber-fiber dispersion is as follows: adding rubber particles to a 10-20wt% NaOH solution and soaking for 12-24 hours, washing and drying to obtain modified rubber; adding basalt fiber to a 40-60wt% sodium starch phosphate solution and soaking for 12-24 hours, drying to obtain modified fiber; adding the modified rubber and modified fiber to an EVA emulsion, and then adding PAM, stirring and ultrasonically vibrating for 10-20 minutes to obtain a modified rubber-fiber dispersion.

[0014] Preferably, the rubber particles are waste tire rubber particles with a mesh size of 10 to 80 and an apparent density of 740 to 760 kg / m 3 .

[0015] Preferably, the basalt fiber has an average length of 12 to 20 mm, a diameter of 10 to 25 μm, and a density of 2.60 to 2.75 g / cm 3, tensile strength 1000~1100MPa, elastic modulus 6~10GPa, elongation at break <3%.

[0016] Preferably, the weight ratio of modified rubber, modified fiber, EVA emulsion and PAM is 1:1.5-2:3-5:0.5-1.

[0017] The present invention also claims a method for preparing the flexible concrete, comprising the following steps:

[0018] (1) Add coarse aggregate, fine aggregate, modified rubber-fiber dispersion, modified cement, fly ash, and water into a mixer in order by weight, and dry mix for 3 to 5 minutes to obtain a slurry;

[0019] (2) Add water reducing agent and air entraining agent to the slurry and stir for 3 to 5 minutes to obtain a flexible concrete material.

[0020] The present invention also claims protection for an application of the flexible concrete in an assembled pavement.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1) The present invention provides a flexible concrete material. By using modified cement and modified rubber-fiber dispersion, a flexible concrete prefabricated road slab is prepared that meets the requirements of transportation, lifting and on-site assembly and has the characteristics of both asphalt concrete and cement concrete materials. This effectively solves the problems of rutting on roads with complex traffic volume and the coordination of allowable deformation between prefabricated assembled pavements and supporting foundations, promoting the rapid development and large-scale application of assembled pavements.

[0023] 2) The present invention provides a modified rubber-fiber dispersion, which, when incorporated into concrete materials, can fully utilize the advantages of both rubber and fiber materials, so that the concrete has good ductility, toughness, crack resistance and damage resistance, thereby obtaining a flexible concrete material with low elastic modulus and high toughness.

[0024] 3) The present invention provides a modified rubber-fiber dispersion. Pre-treating rubber particles with a NaOH solution can improve the hydrophilicity of the rubber aggregate surface and the performance of the interface transition zone in concrete, effectively improve the bonding strength between the rubber aggregate and cement stone, affect the migration behavior of water in concrete, and further affect the water absorption and drying shrinkage of the concrete, thereby improving the workability of the concrete and reducing the loss of concrete strength caused by the addition of rubber particles; basalt fiber is modified using sodium starch phosphate, and the phosphate group chemically bonds with the fiber surface, which can increase the fiber surface roughness and specific surface area, and can also improve the tensile strength and elongation at break of the basalt fiber, thereby improving the flexibility of the concrete material; EVA emulsion has strong acid and alkali corrosion resistance and strong bonding properties, which can enhance the bonding between rubber and basalt fiber. Through a dispersant and ultrasonic vibration, the rubber and basalt fiber are evenly distributed in the EVA emulsion, and finally a modified rubber and modified basalt fiber blend is obtained.

[0025] 4) The present invention provides a modified cement, wherein the epoxy resin can affect the initial dissolution process of the main minerals in the cement, reduce the hydration heat release rate, prolong the setting time of the cement-based material, promote the growth of silicate crystals in the cement-based material, and enhance the flexural strength and toughness of the cement-based material. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0027] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from commercially purchased raw materials.

[0028] The present invention will be further described below with reference to specific examples.

[0029] Example 1

[0030] A method for preparing a flexible concrete material suitable for assembled pavement comprises the following steps:

[0031] (1) 10-mesh rubber particles were added to a 20 wt% NaOH solution and soaked for 24 h, washed, and dried to obtain modified rubber; basalt fiber was added to a 60 wt% sodium starch phosphate solution and immersed for 24 h, and dried to obtain modified fiber; 10 g of modified rubber and 20 g of modified fiber were added to 50 g of EVA emulsion, and then 10 g of PAM was added, stirred, and ultrasonically vibrated for 20 min to obtain a modified rubber-fiber dispersion;

[0032] (2) Add 20 g of epoxy resin E51 to 100 g of PO42.5 ordinary Portland cement and stir evenly to obtain modified cement;

[0033] (3) 1133 g of coarse aggregate, 549 g of fine aggregate, 45 g of modified rubber-fiber dispersion, 447 g of modified cement, 40 g of fly ash, and 210 g of water were added to a mixer in order by weight and dry-mixed for 5 min to obtain a slurry;

[0034] (4) Add 4 g of water reducer and 0.5 g of air entraining agent to the slurry and stir for 5 min to obtain a flexible concrete material.

[0035] Example 2

[0036] A method for preparing a flexible concrete material suitable for assembled pavement comprises the following steps:

[0037] (1) 10-mesh rubber particles were added to a 20 wt% NaOH solution and soaked for 24 h, washed, and dried to obtain modified rubber; basalt fiber was added to a 60 wt% sodium starch phosphate solution and immersed for 24 h, and dried to obtain modified fiber; 10 g of modified rubber and 20 g of modified fiber were added to 50 g of EVA emulsion, and then 10 g of PAM was added, stirred, and ultrasonically vibrated for 20 min to obtain a modified rubber-fiber dispersion;

[0038] (2) Add 20 g of epoxy resin E51 to 100 g of PO42.5 ordinary Portland cement and stir evenly to obtain modified cement;

[0039] (3) 1133 g of coarse aggregate, 549 g of fine aggregate, 35 g of modified rubber-fiber dispersion, 447 g of modified cement, 40 g of fly ash, and 210 g of water were added to a mixer in order by weight and dry-mixed for 5 min to obtain a slurry;

[0040] (4) Add 4 g of water reducer and 0.5 g of air entraining agent to the slurry and stir for 5 min to obtain a flexible concrete material.

[0041] Example 3

[0042] A method for preparing a flexible concrete material suitable for assembled pavement comprises the following steps:

[0043] (1) 10-mesh rubber particles were added to a 20 wt% NaOH solution and soaked for 24 h, washed, and dried to obtain modified rubber; basalt fiber was added to a 60 wt% sodium starch phosphate solution and immersed for 24 h, and dried to obtain modified fiber; 10 g of modified rubber and 20 g of modified fiber were added to 50 g of EVA emulsion, and then 10 g of PAM was added, stirred, and ultrasonically vibrated for 20 min to obtain a modified rubber-fiber dispersion;

[0044] (2) Add 20 g of epoxy resin E51 to 100 g of PO42.5 ordinary Portland cement and stir evenly to obtain modified cement;

[0045] (3) 1133 g of coarse aggregate, 549 g of fine aggregate, 60 g of modified rubber-fiber dispersion, 447 g of modified cement, 40 g of fly ash, and 210 g of water were added to a mixer in order by weight and dry-mixed for 5 min to obtain a slurry;

[0046] (4) Add 4 g of water reducer and 0.5 g of air entraining agent to the slurry and stir for 5 min to obtain a flexible concrete material.

[0047] Comparative Example 1

[0048] A method for preparing a concrete material comprises the following steps:

[0049] (1) 10-mesh rubber particles were added to a 20 wt% NaOH solution and soaked for 24 h, washed, and dried to obtain modified rubber; basalt fiber was added to a 60 wt% sodium starch phosphate solution and immersed for 24 h, and dried to obtain modified fiber; 10 g of modified rubber and 20 g of modified fiber were added to 50 g of EVA emulsion, and then 10 g of PAM was added, stirred, and ultrasonically vibrated for 20 min to obtain a modified rubber-fiber dispersion;

[0050] (2) 1133 g of coarse aggregate, 549 g of fine aggregate, 45 g of modified rubber-fiber dispersion, 447 g of PO42.5 ordinary Portland cement, 40 g of fly ash, and 210 g of water were added to a mixer in order by weight and dry-mixed for 5 min to obtain a slurry;

[0051] (3) Add 4 g of water reducer and 0.5 g of air entraining agent to the slurry and stir for 5 min to obtain concrete material.

[0052] Comparative Example 2

[0053] A method for preparing a concrete material comprises the following steps:

[0054] (1) Add 20 g of epoxy resin E51 to 100 g of PO42.5 ordinary Portland cement and stir evenly to obtain modified cement;

[0055] (2) 1133 g of coarse aggregate, 549 g of fine aggregate, 15 g of 10-mesh rubber particles, 30 g of basalt fiber, 447 g of modified cement, 40 g of fly ash, and 210 g of water were added to a mixer in order by weight and dry-mixed for 5 min to obtain a slurry;

[0056] (3) Add 4 g of water reducer and 0.5 g of air entraining agent to the slurry and stir for 5 min to obtain concrete material.

[0057] The concrete materials prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were respectively subjected to performance tests. The 28d compressive strength, 28d flexural strength, and splitting tensile strength of the concrete were measured with reference to GB / T50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Ordinary Concrete", the elastic modulus of the concrete was measured with reference to GB / T50082-2019 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete", and the peak load deflection, toughness, and equivalent initial bending strength of the concrete were measured with reference to CECS13-2009 "Standard for Test Methods for Fiber Concrete".

[0058] Table 1 Concrete performance test data

[0059]

[0060]

[0061] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A flexible concrete material suitable for assembled pavement, characterized in that: The present invention is prepared from the following components in parts by weight: 435-460 parts of modified cement, 20-40 parts of fly ash, 0.3-0.5 parts of air entraining agent, 4-6 parts of water reducer, 1100-1200 parts of coarse aggregate, 540-560 parts of fine aggregate, 35-60 parts of modified rubber-fiber dispersion, and 190-230 parts of water; The modified rubber-fiber dispersion is prepared as follows: rubber particles are added to a 10-20 wt% NaOH solution and soaked for 12-24 hours, washed, and dried to obtain modified rubber; basalt fibers are added to a 40-60 wt% sodium starch phosphate solution and soaked for 12-24 hours, and dried to obtain modified fibers; Add modified rubber and modified fiber to EVA emulsion, then add PAM, stir and ultrasonically vibrate for 10-20 minutes to obtain modified rubber-fiber dispersion; The modified cement preparation method comprises: adding epoxy resin to cement and stirring uniformly to obtain the modified cement; the volume ratio of epoxy resin to cement is 10-20:100; The weight ratio of modified rubber, modified fiber, EVA emulsion and PAM is 1: (1.5~2): (3~5): (0.5~1).

2. The flexible concrete material according to claim 1, characterized in that: The fly ash has a fineness value of less than 13%, a water content of less than 1.0%, a SO3 volume fraction of less than 4.5%, and a water solubility of less than 98%.

3. The flexible concrete material according to claim 1, characterized in that: The coarse aggregate is well-graded crushed stone with a particle size of 2 to 20 mm; the fine aggregate is machine-made sand with a fineness modulus of 3.0 to 3.6 and an apparent density of 2500 to 2700 kg / m³.

4. The flexible concrete material according to claim 1, characterized in that The rubber particles are waste tire rubber particles with a mesh size of 10-80 and an apparent density of 740-760 kg / m³.

5. The flexible concrete material according to claim 1, characterized in that: The basalt fiber has an average length of 12-20 mm, a diameter of 10-25 μm, a density of 2.60-2.75 g / cm³, a tensile strength of 1000-1100 MPa, an elastic modulus of 6-10 GPa, and an elongation at break of less than 3%.

6. A method for preparing the flexible concrete according to any one of claims 1 to 5, characterized in that: The steps include: (1) Add coarse aggregate, fine aggregate, modified rubber-fiber dispersion, modified cement, fly ash, and water into a mixer in order by weight and stir for 3-5 minutes to obtain a slurry; (2) Add water reducer and air entraining agent to the slurry and stir for 3 to 5 minutes to obtain flexible concrete material.

7. Use of the flexible concrete according to any one of claims 1 to 5 in an assembled pavement.

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