Polymer modified recycled aggregate concrete material, concrete slab and preparation method thereof

Abstract

The invention discloses a polymer modified recycled aggregate concrete material which comprises the following components in parts by mass: 70-90 parts of modified recycled aggregate B; 0-30 parts of cement; 1-3 parts of steel fiber; wherein the modified recycled aggregate B is obtained by modifying a recycled aggregate A through polymer particles; compared with the prior art, after the recycled aggregate A is modified and reinforced by the polymer particles, the strength and toughness of the recycled aggregate A are improved, the strength and toughness of a matrix phase cement-based material are further improved by adding the steel fibers, and integral reinforcement is formed under the condition that the polymer particles penetrate through a three-dimensional network, so that the strength and toughness of the recycled concrete are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of concrete, and in particular to a polymer-modified recycled aggregate concrete material, a concrete board and a preparation method thereof. Background Art

[0002] Compared with natural aggregates, recycled aggregates have old mortar attached to their surface, and have the physical properties of high water absorption, high pressure crushing value, high porosity and low density. In addition, there are multiple interface transition zones inside the recycled concrete prepared from them, resulting in poor performance of the freshly mixed recycled aggregate concrete and poor performance stability, making it difficult to achieve widespread application in engineering.

[0003] In the prior art, mechanical grinding, wrapping or soaking in cement slurry or alkali solution, biological deposition and other methods are used to improve the strength of aggregates; for example, CN115572135B discloses a method for preparing high-strength corrosion-resistant recycled concrete, comprising the following steps:

[0004] Step 1: crushing the waste concrete blocks, screening out the recycled concrete coarse aggregate and the recycled concrete fine aggregate, and then weighing the recycled concrete coarse aggregate and the recycled concrete fine aggregate for later use;

[0005] Step 2: adding silicate cement, fly ash, water reducing agent, bentonite, reinforcing steel fiber, modified phenolic fiber and water to the recycled concrete coarse aggregate and the recycled concrete fine aggregate, stirring and mixing to obtain a mixed slurry;

[0006] Step 3: Pour the mixed slurry in step 2 into the formwork, compact it, sprinkle water for curing, and demold it to obtain high-strength and corrosion-resistant recycled concrete.

[0007] The high-strength corrosion-resistant recycled concrete uses waste concrete as the aggregate of the concrete, which effectively saves resources, makes full use of construction waste, reduces the cost of processing construction waste, and turns waste into treasure. Water reducing agent, bentonite, reinforced steel fiber, and modified phenolic fiber are added to the concrete aggregate. The surface of the steel fiber is copper-plated to increase the roughness of the steel fiber surface, thereby increasing the specific surface area, and then the copper-plated surface is treated with a treatment liquid containing sodium dodecyl sulfate, coumarone resin, and silicon. Alkane coupling agent, stearic acid, polyvinyl alcohol and sulfobutyl-β-cyclodextrin, coumarone resin and sulfobutyl-β-cyclodextrin have strong bonding properties and can be loaded on the rough copper-plated surface after being blended with stearic acid and polyvinyl alcohol. When mixed with mixed aggregate, the reinforcing steel fiber can enter the gap inside the recycled aggregate. Due to the bonding properties of coumarone resin and sulfobutyl-β-cyclodextrin, the gap inside the recycled aggregate can be effectively shrunk, thereby effectively improving the mechanical properties, crack resistance and anti-penetration properties of the recycled concrete.

[0008] However, a large amount of additives are used in the above-mentioned high-strength corrosion-resistant recycled concrete, which results in a relatively high cost. In addition, the compressive strength of the high-strength corrosion-resistant recycled concrete is about 50 MPa, and its compressive resistance is relatively poor. Summary of the invention

[0009] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a polymer-modified recycled aggregate concrete material, a concrete slab and a preparation method thereof, so as to solve the problems in the prior art that the cost of recycled concrete is relatively high and the compressive strength is relatively poor.

[0010] To achieve the above-mentioned object, the first aspect of the present invention adopts the following technical solution: a polymer-modified recycled aggregate concrete material, calculated by weight, comprising:

[0011] Modified recycled aggregate B 70-90 parts;

[0012] 10-30 parts of cement;

[0013] 1-3 parts of steel fiber;

[0014] The modified recycled aggregate B is obtained by modifying the recycled aggregate A with polymer particles.

[0015] Preferably, the mass ratio of the recycled aggregate A to the polymer particles is 10:0.5-1.5.

[0016] Preferably, the polymer particles are one or more of nylon 6, nylon 66, and nylon 610.

[0017] Preferably, the particle size of the recycled aggregate A is 0.16-4.75 mm.

[0018] The second aspect of the present invention also adopts the following technical solution: a concrete slab is formed by pressing and curing the polymer modified recycled aggregate concrete material described in the first aspect of the present invention.

[0019] The third aspect of the present invention also adopts the following technical solution: According to the preparation method of the polymer modified recycled aggregate concrete material described in the first aspect of the present invention, the method comprises the following steps:

[0020] Recycle waste concrete from construction projects and crush it to form recycled aggregate A;

[0021] The recycled aggregate A is mixed with polymer particles at a temperature of 220-260°C for 10-30 minutes, and then cooled and crushed to form modified recycled aggregate B;

[0022] The modified recycled aggregate B, cement and steel fiber are mixed evenly.

[0023] The fourth aspect of the present invention also adopts the following technical solution: the method for preparing the concrete slab according to the second aspect of the present invention comprises the following steps:

[0024] Pressing the polymer modified recycled aggregate concrete material into a board at 270° C. and 10 MPa;

[0025] The panels were then cured at 80°C for 48 hours and then immersed in water for 26 days.

[0026] Technical principle:

[0027] The recycled aggregate A is modified by using polymer particles. The polymer particles melt at high temperature and become liquid. They can penetrate into the cracks of the recycled aggregate A and can also wrap the recycled aggregate A, forming a polymer film on the surface of the recycled aggregate A, so that the modified recycled aggregate B has high strength and low water absorption. In addition, after the modified recycled aggregate B is mixed with cement and steel fiber, the polymer on the surface of the modified recycled aggregate B melts again under high temperature and high pressure and then penetrates into the surface of some cement particles and steel fibers to form a polymer network structure inside the polymer modified recycled aggregate concrete material, which solidifies into a three-dimensional isolated structure after cooling. After steam and immersion curing, the cement is hydrated and the steel fibers are solidified to further improve the overall strength, so that the recycled concrete has good strength and toughness.

[0028] Furthermore, since the polymer particles are nylon, they have strong adhesiveness and can improve the interface strength between aggregate and cement. After cooling, the compressive strength of nylon usually reaches more than 60 MPa and the flexural strength reaches more than 90 MPa.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The polymer modified recycled aggregate concrete material mainly includes recycled aggregate A, polymer particles, cement and steel fiber, and has few components and relatively low cost;

[0031] 2. After the recycled aggregate A is modified and strengthened by polymer particles, the strength and toughness of the recycled aggregate A are improved. The addition of steel fibers further improves the strength and toughness of the matrix phase cement-based materials, and forms an overall reinforcement under the three-dimensional network of polymer particles, thereby significantly improving the strength and toughness of the recycled concrete;

[0032] 3. The preparation process is simple, the operation and control are convenient, and continuous production is possible. It has strong industrialization capabilities and broad market prospects. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below through specific embodiments:

[0034] Example 1

[0035] Step 1: Recycle the waste concrete from the construction project and crush it into recycled aggregate A with a particle size of 0.16 to 4.75 mm;

[0036] Step 2: Put recycled aggregate A, nylon 610 particles and nylon 6 in a high-temperature mixer at a mass ratio of 10:0.25:0.25, mix at 220°C for 30 minutes, and form modified recycled aggregate B after cooling and crushing;

[0037] Step 3: Evenly mix 70 parts of modified recycled aggregate B, 30 parts of cement and 1 part of steel fiber to form recycled concrete dry material C.

[0038] Step 4: Press the recycled concrete dry material C into a plate D in a high temperature and high pressure device at 270°C and 10MPa;

[0039] Step 5: Place plate D in 80°C steam curing for 48 hours, then soak it in water for 26 days and then test its performance.

[0040] Example 2

[0041] Step 1: Recycle the waste concrete from the construction project and crush it into recycled aggregate A with a particle size of 0.16 to 4.75 mm;

[0042] Step 2: Put the recycled aggregate A and nylon 66 particles in a high-temperature mixer at a mass ratio of 10:1.5, mix them at 260°C for 10 minutes, and form modified recycled aggregate B after cooling and crushing;

[0043] Step 3: Evenly mix 90 parts of modified recycled aggregate B, 10 parts of cement, and 3 parts of steel fiber to form recycled concrete dry material C.

[0044] Step 4: Press the recycled concrete dry material C into a plate D in a high temperature and high pressure device at 270°C and 10MPa;

[0045] Step 5: Place plate D in 80°C steam curing for 48 hours, then soak it in water for 26 days and then test its performance.

[0046] Example 3

[0047] Step 1: Recycle the waste concrete from the construction project and crush it into recycled aggregate A with a particle size of 0.16 to 4.75 mm;

[0048] Step 2: Put the recycled aggregate A and nylon 6 particles in a high-temperature mixer at a mass ratio of 10:1, mix them at 240°C for 20 minutes, and form modified recycled aggregate B after cooling and crushing;

[0049] Step 3: Evenly mix 80 parts of modified recycled aggregate B, 20 parts of cement and 2 parts of steel fiber to form recycled concrete dry material C.

[0050] Step 4: Press the recycled concrete dry material C into a plate D in a high temperature and high pressure device at 270°C and 10MPa;

[0051] Step 5: Place plate D in 80°C steam curing for 48 hours, then soak it in water for 26 days and then test its performance.

[0052] Comparative Example 1

[0053] Step 1: Recycle the waste concrete from the construction project and crush it into recycled aggregate A with a particle size of 0.16 to 4.75 mm;

[0054] Step 2: Evenly mix 80 parts of recycled aggregate A, 20 parts of cement, and 2 parts of steel fiber to form recycled concrete dry material B.

[0055] Step 3: Press the recycled concrete dry material B into board D in a high temperature and high pressure device at 270°C and 10MPa;

[0056] Step 4: Place plate D in 80°C steam curing for 48 hours, then soak it in water for 26 days and then test its performance.

[0057] Comparative Example 2

[0058] Step 1: Recycle the waste concrete from the construction project and crush it into recycled aggregate A with a particle size of 0.16 to 4.75 mm;

[0059] Step 2: Put the recycled aggregate A and nylon 6 particles in a high-temperature mixer at a mass ratio of 10:1, mix them at 240°C for 20 minutes, and form modified recycled aggregate B after cooling and crushing;

[0060] Step 3: Evenly mix 80 parts of modified recycled aggregate B and 20 parts of cement to form recycled concrete dry material C.

[0061] Step 4: Press the recycled concrete dry material C into a plate D in a high temperature and high pressure device at 270°C and 10MPa;

[0062] Step 5: Place plate D in 80°C steam curing for 48 hours, then soak it in water for 26 days and then test its performance.

[0063] The test results of compressive strength and flexural strength of the above-mentioned Examples 1-3 and Comparative Examples 1-2 are shown in the following table.

[0064] Compressive strength(MPa) Flexural strength(MPa) Example 1 87.5 12.3 Example 2 56.5 8.5 Example 3 68.2 9.6 Comparative Example 1 26.5 5.1 Comparative Example 2 38.8 6.4

[0065] It can be seen from the above table that the compressive strength of the recycled concrete prepared by the present invention can reach more than 60 MPa, and the flexural strength can reach more than 9 MPa; by comparing Example 3 with Comparative Example 1, since the recycled aggregate A is not modified by polymer particles and is directly mixed with cement and steel fiber, the compressive strength decreases by 61.14%, and the flexural strength decreases by 46.88%; by comparing Example 3 with Comparative Example 2, since steel fiber is not added, the compressive strength decreases by 43.11%, and the flexural strength decreases by 33.33%.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A polymer modified recycled aggregate concrete material, characterized in that: Calculated by mass, including: Modified recycled aggregate B 70-90 parts; 10-30 parts of cement; 1-3 parts of steel fiber; The modified recycled aggregate B is obtained by modifying the recycled aggregate A with polymer particles.

2. The polymer modified recycled aggregate concrete material according to claim 1, characterized in that: The mass ratio of the recycled aggregate A to the polymer particles is 10:0.5-1.

5.

3. The polymer modified recycled aggregate concrete material according to claim 1 or 2, characterized in that: The polymer particles are one or more of nylon 6, nylon 66, and nylon 610.

4. The polymer modified recycled aggregate concrete material according to claim 1 or 2, characterized in that: The particle size of the recycled aggregate A is 0.16-4.75 mm.

5. A concrete slab, characterized in that: The polymer modified recycled aggregate concrete material according to any one of claims 1 to 4 is pressed and then cured.

6. The method for preparing a polymer-modified recycled aggregate concrete material according to any one of claims 1 to 4, characterized in that: The following steps are involved: Recycle waste concrete from construction projects and crush it to form recycled aggregate A; The recycled aggregate A is mixed with polymer particles at a temperature of 220-260°C for 10-30 minutes, and then cooled and crushed to form modified recycled aggregate B; The modified recycled aggregate B, cement and steel fiber are mixed evenly.

7. The method for preparing a concrete slab according to claim 5, characterized in that: The following steps are involved: Pressing the polymer modified recycled aggregate concrete material into a board at 270° C. and 10 MPa; The panels were then cured at 80°C for 48 hours and then immersed in water for 26 days.