Concrete with high elastic modulus and ultra-high performance and preparation method thereof

Abstract

The invention discloses concrete with high elastic modulus and ultra-high performance and a preparation method thereof, and relates to the field of building materials, and the concrete comprises the following components: 420-500 parts of cement, 110-200 parts of a mineral admixture, 810-980 parts of quartz sand, 310-380 parts of brown aluminum oxide aggregate, 25-30 parts of steel fiber, 14-26 parts of a superplasticizer, 100-120 parts of water and 20-30 parts of a nano modifier. According to the invention, the quartz sand and brown aluminum oxide are used as aggregates, so that the use amount of cementing materials such as cement is reduced, and the cost can be saved while the hydration heat release and shrinkage cracking of the materials are reduced. The brown fused alumina aggregates with different particle sizes and brown fused alumina powder in the mineral admixture can enhance the compressive strength, elastic modulus, hardness and water absorption capacity of the concrete.

Description

Technical Field

[0001] The invention relates to the field of building materials, and in particular to a high elastic modulus ultra-high performance concrete and a preparation method thereof. Background Art

[0002] Ultra-high performance concrete (UHPC) has been used in many large-scale buildings, bridges and other projects due to its advantages such as ultra-high strength and good durability. However, with the increasing complexity of engineering requirements, higher requirements are placed on the elastic modulus of concrete. The elastic modulus of existing ordinary ultra-high performance concrete cannot meet certain scenarios with high-strength load-bearing and strict anti-deformation requirements, such as the cable anchorage area of ​​large-span bridges and key parts of high-rise seismic structures. It is urgent to develop a high elastic modulus ultra-high performance concrete to fill this technical gap. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention provides a high elastic modulus ultra-high performance concrete and a preparation method thereof.

[0004] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0005] Provided is a high elastic modulus ultra-high performance concrete comprising the following components:

[0006] 420-500 parts of cement, 110-200 parts of mineral admixture, 810-980 parts of quartz sand, 310-380 parts of brown corundum aggregate, 25-30 parts of steel fiber, 14-26 parts of high-efficiency water reducing agent, 100-120 parts of water, and 20-30 parts of nano modifier.

[0007] Furthermore, the mineral admixture is obtained by mixing silica fume powder, fly ash, slag powder and brown corundum powder in a mass ratio of 1:1:1.3-1.8:0-0.7.

[0008] Furthermore, the particle size of the quartz sand is 6 to 8 mm; the particle size of the brown corundum aggregate is 1 to 5 mm.

[0009] Furthermore, the brown corundum aggregate is obtained by mixing brown corundum coarse aggregate and brown corundum fine aggregate in a ratio of 2:1, the particle size of the brown corundum coarse aggregate is 3-5 mm, the particle size of the brown corundum fine aggregate is 1-3 mm, and the fineness modulus of the brown corundum fine aggregate is 1.3-1.7.

[0010] Furthermore, the nano modifier is obtained by mixing nano silicon dioxide and an organic silane coupling agent in a ratio of 3:1.

[0011] Furthermore, the organic silane coupling agent is KH-550, KH-560 or KH-570 coupling agent.

[0012] Furthermore, the cement is silicate cement or ordinary silicate cement with strength grade 52.5 or 52.5R.

[0013] A method for preparing the above-mentioned high elastic modulus ultra-high performance concrete is characterized by comprising the following steps:

[0014] S1: Dry mix cement, mineral admixture, quartz sand and brown corundum aggregate for later use;

[0015] S2: Take Add water to the blender; add the mixture mixed with S1 to the blender and stir for 2 to 3 minutes;

[0016] S3: Mix the high-efficiency water reducing agent and nano modifier with the remaining water and add them into the mixer, and add steel fiber at the same time, mix and stir for 8 to 10 minutes to obtain a mixture of high elastic modulus ultra-high performance concrete.

[0017] Furthermore, in step S3, after mixing and stirring, a vibrator is used to vibrate for 2 to 4 minutes.

[0018] The beneficial effects of the present invention are:

[0019] The present invention uses quartz sand and brown corundum as aggregates, reduces the amount of cementitious materials such as cement, and can save costs while reducing the heat release and shrinkage cracking of materials during hydration. Brown corundum aggregates of different particle sizes and brown corundum powder in mineral admixtures can enhance the compressive strength, elastic modulus, hardness and water absorption capacity of concrete.

[0020] With the addition of steel fibers, when the concrete material is destroyed, the initial cracks and cavities inside the material expand further, which requires more energy to destroy the material, thus improving the material's resistance to destruction and inhibiting the destruction of the material, the generation and expansion of cracks. The application scope of ultra-high performance concrete is expanded to meet the material requirements of engineering structures that require high strength, high toughness and high durability. DETAILED DESCRIPTION

[0021] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0022] Example 1

[0023] The following preparation method is used to prepare a mixture of high elastic modulus ultra-high performance concrete, specifically:

[0024] S1: Dry mix cement, mineral admixture, quartz sand and brown corundum aggregate for later use;

[0025] Among them, 420-500 parts of cement, cement is silicate cement or ordinary silicate cement with strength grade 52.5 or 52.5R; 110-200 parts of mineral admixture, 810-980 parts of quartz sand, 310-380 parts of brown corundum aggregate; mineral admixture is silica fume powder, fly ash, slag powder and brown corundum powder mixed in a mass ratio of 1:1:1.3-1.8:0.7. The particle size of quartz sand is 6-8mm; the particle size of brown corundum aggregate is 1-5mm. Brown corundum aggregate is obtained by mixing brown corundum coarse aggregate and brown corundum fine aggregate in a ratio of 2:1, the particle size of brown corundum coarse aggregate is 3-5mm, the particle size of brown corundum fine aggregate is 1-3mm, and the fineness modulus of brown corundum fine aggregate is 1.3-1.7.

[0026] S2: Take Add water to the blender; add the mixture mixed with S1 to the blender and stir for 2 to 3 minutes;

[0027] S3: Mix the high-efficiency water reducer and nano modifier with the remaining water, add them to the stirrer, and add steel fiber at the same time. Mix and stir for 8 to 10 minutes, and then vibrate with a vibrator for 2 to 4 minutes; the mixture of high elastic modulus ultra-high performance concrete is obtained. After the obtained mixture is poured into the mold, it is not necessary to vibrate. The high-efficiency water reducer is a polycarboxylic acid high-efficiency water reducer with a water reduction rate of >35%. The nano modifier is obtained by mixing nano silicon dioxide and an organic silane coupling agent in a ratio of 3:1. The organic silane coupling agent is a coupling agent of KH-550, KH-560 or KH-570.

[0028] Example 2

[0029] The difference between this embodiment and embodiment 1 is that there is no brown corundum powder in the mineral admixture. During dry mixing in S1, quartz sand and brown corundum aggregate are first mixed and dry mixed for 5 to 8 minutes, and then cement and other mineral admixtures are added and stirred and mixed.

[0030] Comparative Example 1

[0031] The difference between this comparative example and Example 1 is that the following steps are adopted:

[0032] A1: Dry mix cement, mineral admixture, quartz sand, brown corundum aggregate and nano modifier and set aside;

[0033] A2: Mix the high-efficiency water reducer with water, add all the water into the blender, add the mixture mixed in S1 into the blender and mix well;

[0034] A3: Add the steel fiber into the blender and mix well.

[0035] Comparative Example 2

[0036] The difference between this comparative example and Example 1 is that the brown corundum fine aggregate is replaced by river sand fine aggregate of the same proportion and specification.

[0037] Comparative Example 3

[0038] The difference between this comparative example and Example 1 is that the brown corundum coarse aggregate is replaced by granite coarse aggregate of the same proportion and specification; and the brown corundum fine aggregate is replaced by river sand fine aggregate of the same proportion and specification.

[0039] Comparative Example 4

[0040] The difference between this comparative example and Example 1 is that no nano-modifier is added.

[0041] Examples 1-2 and Comparative Examples 1-4 were prepared into φ100*200 mm ultra-high performance concrete specimens for compressive strength, elastic modulus, Poisson's ratio, splitting strength and hardness tests. The test results on the 28th day are shown in Table 1.

[0042] Table 1

[0043]

[0044] It can be seen from Table 1 that there is no obvious difference in the performance of the test pieces prepared by Example 1 and Example 2.

[0045] Compared with Example 1, Comparative Example 1 has no significant changes in hardness and Poisson's ratio, while the compressive strength, elastic modulus and splitting strength are slightly reduced.

[0046] At the same time, a slump speed comparison experiment was carried out using Comparative Example 1 and Example 1. The results showed that although Comparative Example 1 and Example 1 used the same water-cement ratio, when stirring to the same slump, Comparative Example 1 took 4 to 6 times longer than Example 1; combined with the large rate of change in splitting strength, it may be that at the same mixing time, the slump of Comparative Example 1 was high, resulting in the steel fibers falling and agglomerating in the mixture under the action of vibration, resulting in uneven mixture and affecting the splitting strength.

[0047] Compared with Example 1, except for the Poisson's ratio, the other properties of Comparative Example 2 were significantly reduced.

[0048] Compared with Example 1 and Comparative Example 2, except for the Poisson's ratio, the other properties of Comparative Example 3 are significantly reduced.

[0049] Compared with Example 1, the compressive strength, elastic modulus, splitting strength and hardness of Comparative Example 4 are significantly reduced, and the reduction is greater than that of Comparative Example 1.

[0050] In summary, the compressive strength, elastic modulus, splitting strength and hardness of the present invention are significantly higher than those of granite as coarse aggregate and river sand as fine aggregate; brown corundum aggregate plays an important role in UHPC; and in the preparation process, the use of brown corundum aggregate cannot directly adopt the existing conventional concrete mixing method, and water needs to be added twice to prepare a concrete mixture with a suitable slump in a suitable time. However, in special cases, such as requiring the concrete mixture to have good fluidity, directly using the existing conventional concrete mixing method, the performance of the obtained concrete is reduced less, but high modulus ultra-high performance concrete can also be obtained.

Claims

1. A high elastic modulus ultra-high performance concrete, characterized in that: In parts by weight, it includes the following components: 420-500 parts of cement, 110-200 parts of mineral admixture, 810-980 parts of quartz sand, 310-380 parts of brown corundum aggregate, 25-30 parts of steel fiber, 14-26 parts of high-efficiency water reducing agent, 100-120 parts of water, and 20-30 parts of nano modifier.

2. The high elastic modulus ultra-high performance concrete according to claim 1, characterized in that: The mineral admixture is obtained by mixing silica fume powder, fly ash, slag powder and brown corundum powder in a mass ratio of 1:1:1.3-1.8:0-0.

7.

3. The high elastic modulus ultra-high performance concrete according to claim 1, characterized in that: The particle size of the quartz sand is 6-8 mm; the particle size of the brown corundum aggregate is 1-5 mm.

4. The high elastic modulus ultra-high performance concrete according to claim 3, characterized in that: The brown corundum aggregate is obtained by mixing brown corundum coarse aggregate and brown corundum fine aggregate in a ratio of 2:

1. The particle size of the brown corundum coarse aggregate is 3-5 mm, the particle size of the brown corundum fine aggregate is 1-3 mm, and the fineness modulus of the brown corundum fine aggregate is 1.3-1.

7.

5. The high elastic modulus ultra-high performance concrete according to claim 1, characterized in that: The nano modifier is obtained by mixing nano silicon dioxide and an organic silane coupling agent in a ratio of 3:

1.

6. The high elastic modulus ultra-high performance concrete according to claim 5, characterized in that: The organic silane coupling agent is KH-550, KH-560 or KH-570 coupling agent.

7. The high elastic modulus ultra-high performance concrete according to claim 1, characterized in that: The cement is silicate cement or ordinary silicate cement with strength grade 52.5 or 52.5R.

8. A method for preparing high elastic modulus ultra-high performance concrete according to any one of claims 1 to 7, characterized in that: The steps include: S1: Dry mix cement, mineral admixture, quartz sand and brown corundum aggregate for later use; S2: Take Add water to the blender; add the mixture mixed with S1 to the blender and stir for 2 to 3 minutes; S3: Mix the high-efficiency water reducing agent and nano modifier with the remaining water and add them into the mixer, and add steel fiber at the same time, mix and stir for 8 to 10 minutes to obtain a mixture of high elastic modulus ultra-high performance concrete.

9. The preparation method according to claim 8, characterized in that: In the step S3, after mixing and stirring, a vibrator is used to vibrate for 2 to 4 minutes.

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