A self-compacting lightweight concrete based on modified rubber and preparation method thereof

Abstract

The present invention relates to a self-compacting lightweight concrete based on modified rubber and a preparation method thereof, wherein the concrete comprises by weight: 450-500 parts of cement, 60-80 parts of mineral powder, 40-50 parts of microbeads, 40-50 parts of fly ash, 50-60 parts of silica fume, 550-700 parts of river sand, 0-130 parts of rubber particles, 470-540 parts of ceramsite, 140-160 parts of water, 50-120 parts of steel fiber, 16-20 parts of water reducer, and 0-1 part of thickener; the rubber particles are modified rubber particles, and the modification method of the rubber particles is: the rubber particles are immersed in a polyvinyl acetate modifier solution, and the rubber particles are fully infiltrated with the modifier solution and then dried and stored. The self-compacting lightweight concrete based on modified rubber of the present invention has the advantages of light weight, high strength, high toughness and crack resistance, and suitable viscosity and easy pumping construction.

Description

Technical Field

[0001] The invention relates to the field of concrete materials, and in particular to a self-compacting lightweight concrete based on modified rubber and a preparation method thereof. Background Art

[0002] Self-compacting lightweight concrete is made by replacing part or all of the aggregate in ordinary self-compacting concrete with lightweight aggregate to meet the demand for lightweight concrete in high-rise buildings. It fully combines the advantages of self-compacting concrete that it does not require vibration and lightweight concrete that has a small weight. However, self-compacting lightweight concrete has the disadvantages of being brittle, having poor toughness, poor fatigue resistance, and poor crack resistance. At the same time, lightweight aggregate concrete is more prone to pump blockage than ordinary concrete. The smaller the density of the lightweight aggregate and the larger the particle size, the more difficult it is to pump.

[0003] Rubber concrete is a concrete made by adding a certain amount of waste rubber particles or waste rubber powder to ordinary concrete. It has the characteristics of low elastic modulus, high damping, high energy dissipation and good crack resistance. However, the addition of rubber particles will lead to a significant decrease in the mechanical properties of concrete, mainly because the hydrophobicity of rubber and the hydrophilicity of cement paste make it impossible to form a strong chemical bond between them, and the interfacial bonding force is weak. At the same time, using rubber particles to prepare concrete will make the working performance of concrete worse and reduce fluidity. The higher the amount of rubber particles added, the more obvious the decrease in self-compacting properties, which is not conducive to concrete pumping construction.

[0004] At present, most researchers aim to improve the mechanical properties of rubber concrete by modifying the rubber surface. Common modification methods include water washing, NaOH modification, coupling agent modification, etc. The water washing method will waste water resources and cause water pollution, and the mechanical properties of rubber concrete will not be significantly improved. In the NaOH method, if too much NaOH is added, it will be detrimental to the improvement of the hydrophilic properties of rubber. The optimal concentration is difficult to define, and the rubber needs to be washed with water after modification with NaOH. There are many operation steps. If there is any residue, it will be detrimental to the durability of concrete. The coupling agent production process is complicated and the cost is high.

[0005] Prior art, such as the invention patent with publication number CN111170697A, discloses a modified rubber particle lightweight ultra-high performance concrete and a preparation method thereof, which is prepared with cement, fly ash microbeads, silica fume, pottery sand, rubber particles, copper-plated steel fiber, water-based epoxy resin, water-retaining shrinkage-reducing internal curing agent, water-reducing agent and water as main raw materials. The rubber particles are modified with NaOH, and the obtained concrete is light in weight, strong in impact resistance and abrasion resistance. However, the addition of NaOH-modified rubber particles is still not conducive to concrete pumping. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a self-compacting lightweight concrete based on modified rubber and a preparation method thereof, which combines the advantages of self-compacting lightweight concrete and rubber concrete, and solves the problem that the addition of rubber particles increases the difficulty of concrete pumping.

[0007] The technical objectives of the present invention are achieved through the following technical solutions:

[0008] A self-compacting lightweight concrete based on modified rubber comprises, by weight, 450-500 parts of cement, 60-80 parts of mineral powder, 40-50 parts of microspheres, 40-50 parts of fly ash, 50-60 parts of silica fume, 550-700 parts of river sand, 0-130 parts of rubber particles, 470-540 parts of ceramsite, 140-160 parts of water, 50-120 parts of steel fiber, 16-20 parts of water reducer, and 0-1 part of thickener. The rubber particles are modified rubber particles. The modification method of the rubber particles is: immersing the rubber particles in a modifier solution, fully soaking the rubber particles in the modifier solution, and then drying and storing them. The modifier is a polyvinyl acetate modifier.

[0009] Furthermore, the particle size of the rubber particles before modification is 0.15-4.75 mm, the fineness modulus is 2.6, and the apparent density is 1.16 g / cm 3 , bulk density is 365kg / m 3 .

[0010] Furthermore, the sphericity of the modified rubber particles is 0.68-1.0.

[0011] Furthermore, the cement is P·Ⅱ52.5 silicate cement with a specific surface area of ​​450m 2 / kg-480m 2 / kg, loss on ignition ≤3.5%, sulfur trioxide content ≤3.5%, magnesium oxide content ≤5%.

[0012] Furthermore, the mineral powder is S95 mineral powder with a specific surface area of ​​450m 2 / kg-500m 2 / kg, fluidity ratio ≥95%, 7d activity ≥70%, 28d activity ≥95%.

[0013] Furthermore, the microspheres are fly ash microspheres, the particle size distribution range is 0.5 μm to 4 μm, the SiO2 content is 56.8%, and the specific surface area is 2430 m 2 / kg.

[0014] Furthermore, the fly ash is Class I fly ash, has a water requirement ratio of ≤95%, a specific surface area of ​​645m2 / kg, a loss on ignition of ≤5%, and an activity index of ≥70%.

[0015] Furthermore, the silica fume has SiO2 ≥85.0%, an activity index ≥105%, a total alkali content ≤1.5%, a chlorine content ≤0.1%, and a water demand ratio ≤125%.

[0016] Furthermore, the river sand is medium sand, with a mud content of ≤2.0%, a fineness modulus of 2.6, and an apparent density of 2.62 g / cm 3 , bulk density is 1502kg / m 3 .

[0017] Furthermore, the ceramsite is 800-grade crushed stone shale ceramsite with a particle size of 5-10 mm, a 1h water absorption rate of 2.5%, a cylinder pressure strength of 8.2 MPa, and a bulk density of 830 kg / m 3 .

[0018] Further, the steel fiber is a hook-end type steel fiber with a length of 12 mm and a diameter of 0.21 mm.

[0019] Furthermore, the water reducing agent is a PCA type polycarboxylate water reducing agent, with a water reducing rate of >30% and a density of 1050kg / m 3 -1110kg / m 3 .

[0020] Furthermore, the thickener is hydroxypropyl methylcellulose.

[0021] The present invention also provides a method for preparing a self-compacting lightweight concrete based on modified rubber, the method comprising the following steps:

[0022] Step 1: Pre-wet the ceramsite 1 hour in advance, and record the weight of the ceramsite before and after pre-wetting to determine the water consumption;

[0023] Step 2, the pre-wetted ceramsite is mixed and stirred evenly with river sand, rubber particles modified with polyvinyl acetate modifier, silica ash, mineral powder, fly ash and microbeads to obtain a mixture A;

[0024] Step 3, adding cement, water reducing agent, thickener and remaining water to mixture A and stirring evenly to obtain slurry B;

[0025] Step 4: Add steel fiber to slurry B and stir evenly to obtain self-compacting lightweight concrete based on modified rubber.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The self-compacting lightweight concrete prepared by adding modified rubber in the present invention has excellent workability and pumpability. On the one hand, the present invention effectively suppresses the floating of lightweight aggregate by adding an appropriate amount of thickener; reduces the maximum particle size of aggregate to reduce the required pumping pressure; and designs the composite admixture system and sand ratio to jointly adjust the viscosity and fluidity of the concrete mixture for easy pumping construction; on the other hand, after the present invention uses polyvinyl acetate to modify the rubber, it can increase the bonding force between rubber particles and cement-based materials, and improve the fluidity of concrete based on the sliding property of the polymer chain segment, and at the same time can introduce an appropriate amount of air content. These evenly distributed tiny bubbles can significantly increase the fluidity of the concrete mixture and reduce the plastic viscosity, thereby improving the workability and pumpability of the concrete.

[0028] 2. The present invention replaces a part of river sand with rubber particles, which can reduce the apparent density of concrete, improve the toughness of self-compacting lightweight concrete, prevent concrete cracking, reduce rubber pollution, and realize the reuse of resources.

[0029] 3. The rubber particles of the present invention are relatively round in shape, which can reduce the adverse porosity in the concrete after the rubber particles are added, and at the same time can reduce the large bubble content in the concrete caused by the large amount of air entrained on the rubber surface during mixing, reduce the air content of the concrete, improve the density of the concrete, and thus improve the mechanical properties and working performance of the concrete.

[0030] 4. The present invention uses polyvinyl acetate to modify the surface of rubber particles. The molecular structure of the modifier has a dioxygen bond at the end of the acetate, which is hydrophilic and can form hydrogen bonds with polar molecules in the concrete composition; it has a polyethylene hydrocarbon chain at the other end, which is hydrophobic and can interact with rubber, thereby enhancing the bonding performance between rubber and cement-based materials, improving the compressive strength and tensile strength of concrete, and enhancing the toughness and crack resistance of concrete. The modifier is easy to obtain, economical and friendly, and harmless to people who come into contact with the produced concrete.

[0031] 5. The present invention incorporates steel fibers, which can play a role in toughening, crack resistance and improving the strength of rubber concrete in concrete. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below in conjunction with specific embodiments:

[0033] A self-compacting lightweight concrete based on modified rubber, comprising, by weight: 450-500 parts of cement, 60-80 parts of mineral powder, 40-50 parts of microspheres, 40-50 parts of fly ash, 50-60 parts of silica fume, 550-700 parts of river sand, 0-130 parts of rubber particles, 470-540 parts of ceramsite, 140-160 parts of water, 50-120 parts of steel fiber, 16-20 parts of water reducer, and 0-1 part of thickener;

[0034] The cement is P·Ⅱ52.5 silicate cement with a specific surface area of ​​450m 2 / kg-480m 2 / kg, loss on ignition ≤3.5%, sulfur trioxide content ≤3.5%, magnesium oxide content ≤5%;

[0035] The mineral powder is S95 mineral powder with a specific surface area of ​​450m 2 / kg-500m 2 / kg, mobility ratio ≥95%, 7d activity ≥70%, 28d activity ≥95%;

[0036] The microspheres are fly ash microspheres with a particle size distribution range of 0.5 μm to 4 μm, a SiO2 content of 56.8%, and a specific surface area of ​​2430 m 2 / kg.

[0037] The fly ash is Class I fly ash, with a water requirement ratio of ≤95% and a specific surface area of ​​645m 2 / kg, loss on ignition ≤5%, activity index ≥70%;

[0038] Silica fume SiO2 ≥ 85.0%, activity index ≥ 105%, total alkali content ≤ 1.5%, chlorine content ≤ 0.1%, water requirement ratio ≤ 125%;

[0039] The river sand is medium sand, with mud content ≤2.0%, fineness modulus of 2.6, and apparent density of 2.62g / cm 3 , bulk density is 1502kg / m 3 ;

[0040] The ceramsite is 800 grade crushed stone shale ceramsite with a particle size of 5-10mm, a water absorption rate of 2.5% in 1h, a cylinder pressure strength of 8.2MPa, and a bulk density of 830kg / m 3 ;

[0041] The steel fiber is a hook-end steel fiber with a length of 12 mm and a diameter of 0.21 mm;

[0042] The water reducer is PCA type polycarboxylate water reducer, with a water reduction rate of >30% and a density of 1050kg / m 3 -1110kg / m 3 ;

[0043] The thickener is hydroxypropyl methylcellulose, which is a white powder;

[0044] The rubber particles are modified rubber particles, and the rubber particles are immersed in a modifier solution, the modifier is a polyvinyl acetate modifier, and the modification steps are as follows:

[0045] S1. The waste rubber is mechanically crushed and then shaped. The rubber particle size is 0.15-4.75mm, the fineness modulus is 2.6, and the apparent density is 1.16g / cm 3 , bulk density is 365kg / m 3 , preferably rubber particles with a sphericity of 0.68-1.0;

[0046] S2. Soaking the rubber particles in a polyvinyl acetate modifier, and drying the rubber particles after they are fully soaked to obtain modified rubber particles. The polyvinyl acetate modifier has a solid content of 52% and a pH of 6.

[0047] The present invention also provides a method for preparing the above-mentioned self-compacting lightweight concrete based on modified rubber, comprising the following steps:

[0048] Step 1, pre-wetting the ceramsite 1 hour in advance, and record the weight of the ceramsite before and after pre-wetting to determine the water consumption; the weight change of the ceramsite before and after pre-wetting is the water absorption of the ceramsite, and the total water consumption minus the water absorption of the ceramsite is the subsequent remaining water volume;

[0049] Step 2, the pre-wetted ceramsite is mixed and stirred evenly with river sand, rubber particles modified with polyvinyl acetate modifier, silica ash, mineral powder, fly ash and microbeads to obtain a mixture A;

[0050] Step 3, adding cement, water reducing agent, thickener and remaining water to mixture A and stirring evenly to obtain slurry B;

[0051] Step 4: Add steel fiber to slurry B and stir evenly to obtain self-compacting lightweight concrete based on modified rubber.

[0052] In order to make the effect of the present invention clearer, the present invention provides the following comparative examples and embodiments:

[0053] Comparative Example 1

[0054] A self-compacting lightweight concrete based on modified rubber, wherein the required single proportions of each component are calculated by weight: 457 parts of cement, 66 parts of mineral powder, 40 parts of microspheres, 40 parts of fly ash, 52 parts of silica fume, 700 parts of river sand, 473 parts of ceramsite, 144 parts of water, 71 parts of steel fiber, 18.2 parts of high-efficiency water reducing agent, and 0.06 parts of thickener.

[0055] The specific preparation steps are as follows:

[0056] Step 1: Pre-wet the ceramsite 1 hour in advance and record the weight of the ceramsite before and after pre-wetting;

[0057] Step 2: Add the pre-wetted ceramsite, river sand, silica ash, mineral powder, fly ash and microbeads into a mixer and mix evenly to obtain a mixture A1;

[0058] Step 3: Add cement, water reducing agent, thickener and remaining water to mixture A1 and mix well to obtain slurry B1;

[0059] Step 4: Add steel fiber into slurry B1, mix well and then discharge from the machine.

[0060] Comparative Example 2

[0061] A self-compacting lightweight concrete based on modified rubber, the required single ratio of each component is calculated by weight fraction: 457 parts of cement, 66 parts of mineral powder, 40 parts of microspheres, 40 parts of fly ash, 52 parts of silica fume, 665 parts of river sand, 31 parts of rubber particles, 473 parts of ceramsite, 144 parts of water, 71 parts of steel fiber, 18.2 parts of high-efficiency water reducer, and 0.06 parts of thickener. The specific preparation steps are as follows:

[0062] Step 1: Pre-wet the ceramsite 1 hour in advance and record the weight of the ceramsite before and after pre-wetting;

[0063] Step 2: Add the pre-wetted ceramsite, river sand, rubber particles, silica fume, mineral powder, fly ash and micro beads into a mixer and mix them evenly to obtain a mixture A2;

[0064] Step 3: Add cement, water reducing agent, thickener and remaining water to mixture A2 and mix well to obtain slurry B2;

[0065] Step 4: Add steel fiber into slurry B2, stir evenly and then discharge from the machine.

[0066] Comparative Example 3

[0067] A self-compacting lightweight concrete based on modified rubber, the required single ratio of each component is calculated by weight fraction: 457 parts of cement, 66 parts of mineral powder, 40 parts of microspheres, 40 parts of fly ash, 52 parts of silica fume, 630 parts of river sand, 62 parts of rubber particles, 473 parts of ceramsite, 144 parts of water, 71 parts of steel fiber, 18.2 parts of high-efficiency water reducer, and 0.06 parts of thickener. The specific preparation steps are as follows:

[0068] Step 1: Pre-wet the ceramsite 1 hour in advance and record the weight of the ceramsite before and after pre-wetting;

[0069] Step 2: Add the pre-wetted ceramsite, river sand, rubber particles, silica fume, mineral powder, fly ash and micro beads into a mixer and mix evenly to obtain a mixture A3;

[0070] Step 3: Add cement, water reducing agent, thickener and remaining water to mixture A3 and mix well to obtain slurry B3;

[0071] Step 4: Add steel fiber into slurry B3, mix well and then discharge from the machine.

[0072] Comparative Example 4

[0073] A self-compacting lightweight concrete based on modified rubber, the required single ratio of each component is calculated by weight fraction: 457 parts of cement, 66 parts of mineral powder, 40 parts of microspheres, 40 parts of fly ash, 52 parts of silica fume, 595 parts of river sand, 93 parts of rubber particles, 473 parts of ceramsite, 144 parts of water, 71 parts of steel fiber, 18.2 parts of high-efficiency water reducer, and 0.06 parts of thickener. The specific preparation steps are as follows:

[0074] Step 1: Pre-wet the ceramsite 1 hour in advance and record the weight of the ceramsite before and after pre-wetting;

[0075] Step 2: Add the pre-wetted ceramsite, river sand, rubber particles, silica fume, mineral powder, fly ash and micro beads into a mixer and mix them evenly to obtain a mixture A4;

[0076] Step 3: Add cement, water reducing agent, thickener and remaining water to mixture A4 and mix well to obtain slurry B4;

[0077] Step 4: Add steel fiber into slurry B4, mix well and then discharge from the machine.

[0078] Comparative Example 5

[0079] A self-compacting lightweight concrete based on modified rubber, the required single ratio of each component is calculated by weight fraction: 457 parts of cement, 66 parts of mineral powder, 40 parts of microspheres, 40 parts of fly ash, 52 parts of silica fume, 560 parts of river sand, 124 parts of rubber particles, 473 parts of ceramsite, 144 parts of water, 71 parts of steel fiber, 18.2 parts of high-efficiency water reducer, and 0.06 parts of thickener. The specific preparation steps are as follows:

[0080] Step 1: Pre-wet the ceramsite 1 hour in advance and record the weight of the ceramsite before and after pre-wetting;

[0081] Step 2: Add the pre-wetted ceramsite, river sand, rubber particles, silica fume, mineral powder, fly ash and micro beads into a mixer and mix evenly to obtain a mixture A5;

[0082] Step 3: Add cement, water reducing agent, thickener and remaining water to mixture A5 and mix well to obtain slurry B5;

[0083] Step 4: Add steel fiber into slurry B5, mix well and then discharge from the machine.

[0084] Example 1

[0085] A self-compacting lightweight concrete based on modified rubber, which is different from Comparative Example 2 in that the modifier is 7.8 parts. The specific preparation steps are as follows:

[0086] Step 1: Soak the rubber particles in the modifier in advance for modification, and after sufficient soaking, dry the rubber particles and store them for later use;

[0087] Step 2: Pre-wet the ceramsite 1 hour in advance and record the weight of the ceramsite before and after pre-wetting;

[0088] Step 3: Add the pre-wetted ceramsite, river sand, rubber particles, silica fume, mineral powder, fly ash and micro beads into a mixer and mix evenly to obtain a mixture A6;

[0089] Step 4: Add cement, water reducing agent, thickener and remaining water to mixture A6 and mix well to obtain slurry B6;

[0090] Step 5: Add steel fiber to slurry B6, mix well and then exit the machine.

[0091] Example 2

[0092] A self-compacting lightweight concrete based on modified rubber, which is different from Comparative Example 3 in that the modifier is 15.5 parts. The specific preparation steps are as follows:

[0093] Step 1: Soak the rubber particles in the modifier in advance for modification, and after sufficient soaking, dry the rubber particles and store them for later use;

[0094] Step 2: Pre-wet the ceramsite 1 hour in advance and record the weight of the ceramsite before and after pre-wetting;

[0095] Step 3: Add the pre-wetted ceramsite, river sand, rubber particles, silica fume, mineral powder, fly ash and micro beads into a mixer and mix evenly to obtain a mixture A7;

[0096] Step 4: Add cement, water reducing agent, thickener and remaining water to mixture A7 and mix well to obtain slurry B7;

[0097] Step 5: Add steel fiber into slurry B7, stir evenly and then discharge from the machine.

[0098] Example 3

[0099] A self-compacting lightweight concrete based on modified rubber, which is different from Comparative Example 4 in that the modifier is 23.3 parts. The specific preparation steps are as follows:

[0100] Step 1: Soak the rubber particles in the modifier in advance for modification, and after sufficient soaking, dry the rubber particles and store them for later use;

[0101] Step 2: Pre-wet the ceramsite 1 hour in advance and record the weight of the ceramsite before and after pre-wetting;

[0102] Step 3: Add the pre-wetted ceramsite, river sand, rubber particles, silica fume, mineral powder, fly ash and micro beads into a mixer and mix evenly to obtain a mixture A8;

[0103] Step 4: Add cement, water reducing agent, thickener and remaining water to mixture A8 and mix well to obtain slurry B8;

[0104] Step 5: Add steel fiber into slurry B8, stir evenly and then discharge from the machine.

[0105] Example 4

[0106] A self-compacting lightweight concrete based on modified rubber, which is different from Comparative Example 5 in that the modifier is 31.0 parts. The specific preparation steps are as follows:

[0107] Step 1: Soak the rubber particles in the modifier in advance for modification, and after sufficient soaking, dry the rubber particles and store them for later use;

[0108] Step 2: Pre-wet the ceramsite 1 hour in advance and record the weight of the ceramsite before and after pre-wetting;

[0109] Step 3: Add the pre-wetted ceramsite, river sand, rubber particles, silica ash, mineral powder, fly ash and micro beads into a mixer and mix evenly to obtain a mixture A9;

[0110] Step 4: Add cement, water reducing agent, thickener and remaining water to mixture A9 and mix evenly to obtain slurry B9;

[0111] Step 5: Add the steel fiber evenly into slurry B9, stir evenly and then discharge from the machine.

[0112] Table 1 Comparative proportions

[0113]

[0114]

[0115] Table 2 Example mix ratio

[0116] The test data after verification are shown in Table 3 below:

[0117] Table 3 Test items and data

[0118]

[0119]

[0120] From Table 3, we can see that:

[0121] (1) From Comparative Examples 1-5, it can be seen that as the amount of unmodified rubber particles increases, the expansion, 28d compressive strength and 28d splitting tensile strength of the prepared concrete gradually decrease, and the tension-compression ratio and plastic viscosity gradually increase. This shows that the unmodified rubber particles have an adverse effect on the compressive strength and tensile strength of the concrete, increasing the difficulty of pumping, but can improve the toughness of the concrete, thereby reducing the potential cracks caused by shrinkage of the concrete.

[0122] (2) Compared with Comparative Example 1, the maximum increase in the concrete tension-compression ratio of Examples 1-4 is 17.5%, which fully demonstrates the toughening effect of the rubber particles and the ability to prevent concrete cracking.

[0123] (3) Compared with Comparative Examples 2-5, the concrete prepared by modified rubber particles in Examples 1-4 has a 28d compressive strength increased by 11.0%-20.4%, a splitting tensile strength increased by 11.4%-23.2%, and an expansion increased by 3.6%-8.2% compared with the concrete prepared by unmodified rubber particles. The tensile-compression ratio is higher than that of the concrete prepared by adding unmodified rubber particles, and the plastic viscosity also shows a generally decreasing trend compared with the unmodified concrete. This shows that the addition of modified rubber particles can improve the mechanical properties and workability of concrete, and can also improve the pumping performance, toughness and crack resistance of concrete.

[0124] This embodiment is only a further explanation of the present invention, not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed, but as long as it is within the scope of the claims of the present invention, it will be protected by the patent law.

Claims

1. A self-compacting lightweight concrete based on modified rubber, characterized in that: The concrete comprises, by weight, 450-500 parts of cement, 60-80 parts of mineral powder, 40-50 parts of microspheres, 40-50 parts of fly ash, 50-60 parts of silica fume, 550-700 parts of river sand, 0-130 parts of rubber particles, 470-540 parts of ceramsite, 140-160 parts of water, 50-120 parts of steel fiber, 16-20 parts of water reducer, and 0-1 part of thickener; the rubber particles are modified rubber particles; the modification method of the rubber particles is: immersing the rubber particles in a modifier solution, fully soaking the rubber particles in the modifier solution, and then drying and storing; the modifier is a polyvinyl acetate modifier; The particle size of the rubber particles before modification is 0.15-4.75 mm, the fineness modulus is 2.6, and the apparent density is 1.16 g / cm 3 , bulk density is 365kg / m 3 ; The sphericity of the modified rubber particles is 0.68-1.

0.

2. A self-compacting lightweight concrete based on modified rubber according to claim 1, characterized in that: The cement is P·Ⅱ52.5 silicate cement with a specific surface area of ​​450m 2 / kg-480m 2 / kg, loss on ignition ≤3.5%, sulfur trioxide content ≤3.5%, magnesium oxide content ≤5%.

3. A self-compacting lightweight concrete based on modified rubber according to claim 1, characterized in that: The mineral powder is S95 mineral powder with a specific surface area of ​​450m 2 / kg-500m 2 / kg, fluidity ratio ≥95%, 7d activity ≥70%, 28d activity ≥95%.

4. A self-compacting lightweight concrete based on modified rubber according to claim 1, characterized in that: The microbeads are fly ash microbeads, with a particle size distribution range of 0.5 μm to 4 μm, a SiO2 content of 56.8%, and a specific surface area of ​​2430 m 2 / kg.

5. The self-compacting lightweight concrete based on modified rubber according to claim 1, characterized in that: The fly ash is Class I fly ash, with a water requirement ratio of ≤95% and a specific surface area of ​​645m 2 / kg, loss on ignition ≤5%, activity index ≥70%.

6. A self-compacting lightweight concrete based on modified rubber according to claim 1, characterized in that: The silica fume has SiO2≥85.0%, an activity index≥105%, a total alkali content≤1.5%, a chlorine content≤0.1%, and a water requirement ratio≤125%.

7. A self-compacting lightweight concrete based on modified rubber according to claim 1, characterized in that: The river sand is medium sand, with a mud content of ≤2.0%, a fineness modulus of 2.6, and an apparent density of 2.62 g / cm 3 , bulk density is 1502kg / m 3 .

8. The self-compacting lightweight concrete based on modified rubber according to claim 1, characterized in that: The ceramsite is 800-grade crushed stone shale ceramsite with a particle size of 5-10 mm, a 1h water absorption rate of 2.5%, a cylinder pressure strength of 8.2 MPa, and a bulk density of 830 kg / m 3 .

9. The self-compacting lightweight concrete based on modified rubber according to claim 1, characterized in that: The steel fiber is a hook-end steel fiber with a length of 12 mm and a diameter of 0.21 mm.

10. The self-compacting lightweight concrete based on modified rubber according to claim 1, characterized in that: The water reducer is a PCA type polycarboxylate water reducer with a water reduction rate of >30% and a density of 1050 kg / m 3 -1110 kg / m 3 .

11. The self-compacting lightweight concrete based on modified rubber according to claim 1, characterized in that: The thickener is hydroxypropyl methylcellulose.

12. A method for preparing a self-compacting lightweight concrete based on modified rubber according to any one of claims 1 to 11, characterized in that: The method comprises the following steps: Step 1: Pre-wet the ceramsite 1 hour in advance, and record the weight of the ceramsite before and after pre-wetting to determine the water consumption; Step 2, mixing the pre-wetted ceramsite with river sand, rubber particles modified by polyvinyl acetate modifier, silica ash, mineral powder, fly ash and microbeads to obtain a mixture A; Step 3, adding cement, water reducing agent, thickener and remaining water to mixture A and stirring evenly to obtain slurry B; Step 4: Add steel fiber to slurry B and stir evenly to obtain self-compacting lightweight concrete based on modified rubber.

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