An ultra-high performance concrete containing volcanic rock powder and a preparation method and application thereof

Abstract

The application relates to an ultra-high performance concrete containing volcanic rock powder and a preparation method and application thereof, the ultra-high performance concrete comprises the following components in parts by weight: cement 700-750 parts, silica flour 40-50 parts, volcanic rock powder 500-550 parts, machine-made sand 1800-2000 parts, water reducing agent 25-35 parts, and water 195-205 parts; the specific surface area of the volcanic rock powder is greater than or equal to 500 m 2 / kg, and the loss on ignition is less than or equal to 1.5%. Compared with the prior art, the ultra-high performance concrete can not only enhance the compressive strength of the ultra-high performance concrete, but also effectively reduce the drying shrinkage of the ultra-high performance concrete.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, and in particular relates to an ultra-high performance concrete containing volcanic rock powder, its preparation method and application. Background Technology

[0002] Ultra-high performance concrete (UHVPC) generally refers to concrete with a cubic compressive strength greater than 120 MPa. Due to its high strength, high corrosion resistance, and durability, UHVPC offers advantages such as reduced structural size, lighter structural weight, land savings, lower energy consumption, and lower structural maintenance and reconstruction costs. Therefore, it is widely used in structures, and its technological development has become a key focus and research area in the construction industry. Furthermore, with the increasing trend in building design towards high-rise and super high-rise buildings, large spans, underground structures, and harsh service environments for concrete, UHVPC has significant application advantages in large-scale projects such as super high-rise buildings, cross-sea bridges, and offshore oil platforms.

[0003] However, existing ultra-high performance concrete uses a high amount of cement (usually as high as 800-1000 kg / m³). 3 The high heat of hydration and severe shrinkage cracking in ultra-high performance concrete (UHVPC) result in high early-stage hydration heat and significant shrinkage cracking. Furthermore, its low water-cement ratio (typically less than 0.2) leads to high viscosity in the concrete paste, posing challenges in practical construction. In addition, commonly used UHVPC mix designs require a wide variety of cementitious materials, typically four or more, and the cement used is 52.5 silicate cement, further limiting its application in real-world engineering projects.

[0004] With the increasing development of admixture technologies such as nanomaterials (CN114890742A), high-strength fibers (CN113620661A), and others, the compressive strength of ultra-high performance concrete has been significantly improved. However, technical problems such as easy drying shrinkage, low fluidity, and construction difficulties still need to be solved. Summary of the Invention

[0005] The purpose of this invention is to overcome the defect of easy drying shrinkage in existing ultra-high performance concrete and to provide an ultra-high performance concrete containing volcanic rock powder, its preparation method and application.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] An ultra-high performance concrete containing volcanic rock powder comprises the following components by weight: 700-750 parts cement, 40-50 parts silica fume, 500-550 parts volcanic rock powder, 1800-2000 parts manufactured sand, 25-35 parts water-reducing agent, and 195-205 parts water; wherein the specific surface area of ​​the volcanic rock powder is ≥500 m² / g. 2 / kg, loss on ignition not greater than 1.5%.

[0008] Furthermore, the particle size distribution of the volcanic rock powder is 0.3–240 μm.

[0009] Furthermore, the micropore distribution of the volcanic rock powder is 5–140 nm.

[0010] Furthermore, the volcanic rock powder has a 28-day activity index ≥105%.

[0011] Furthermore, the cement is silicate cement, and the standard consistency water content of the cement is no more than 26%.

[0012] Furthermore, the cement is P·O 42.5 ordinary Portland cement, and the 28-day mortar compressive strength of the cement is ≥48MPa.

[0013] Furthermore, the particle size distribution of the silica fume is 200-1000 nm.

[0014] Furthermore, the fineness modulus of the manufactured sand is 2.7 to 3.0, the stone powder content is ≤3 wt%, and the clay content is ≤0.5 wt%.

[0015] Furthermore, the manufactured sand is Zone II sand with a fineness modulus of 2.7 to 3.0 and an MB value of less than 1.4.

[0016] Furthermore, the water-reducing agent is a liquid polycarboxylate-based water-reducing agent.

[0017] Furthermore, the water-reducing agent has a solid content between 35% and 45% and a water reduction rate of ≥30%.

[0018] Furthermore, the 28-day compressive strength of the ultra-high performance concrete is ≥140MPa.

[0019] The present invention also provides a method for preparing ultra-high performance concrete containing volcanic rock powder, comprising the following steps: mixing the components in proportion and mechanically stirring for 2-5 minutes to obtain the ultra-high performance concrete.

[0020] This invention also provides an application of ultra-high performance concrete containing volcanic rock powder as a high-strength building material.

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

[0022] (1) The ultra-high performance concrete of the present invention contains loose and porous volcanic rock powder, which can not only enhance the compressive strength of ultra-high performance concrete, with a 28-day compressive strength of not less than 140 MPa, but also effectively reduce the drying shrinkage of ultra-high performance concrete.

[0023] (2) The volcanic rock powder of the present invention is a highly active natural auxiliary cementitious material that can replace the slag powder and fly ash in the original ultra-high performance concrete, and can further replace part of the cement, effectively reducing the amount of cement used and reducing carbon emissions.

[0024] (3) The volcanic rock powder of the present invention has a small adsorption of water-reducing agent, and will not cause an increase in the fluidity loss of concrete paste under high dosage.

[0025] (4) The ultra-high performance concrete prepared by this invention uses relatively low cement content, large mineral admixture content, short concrete mixing time, and low overall cost, and can achieve large-scale production, with broad application prospects. Attached Figure Description

[0026] Figure 1 This is a surface morphology diagram of the volcanic rock powder particles of the present invention.

[0027] Figure 2 This describes the particle size distribution of the volcanic rock powder particles of the present invention.

[0028] Figure 3 This describes the micropore distribution of volcanic rock powder particles according to the present invention. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0030] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available. The volcanic rock powder of this invention was purchased from Tibet Wuyang Industrial Co., Ltd.; the water-reducing agent was manufactured by Sika (China) Co., Ltd. 1200 series polycarboxylate superplasticizer.

[0031] Example 1:

[0032] An ultra-high performance concrete containing volcanic rock powder has the following components per cubic meter: 720 kg cement, 43 kg silica fume, 525 kg volcanic rock powder, 1960 kg manufactured sand, 33 kg water-reducing agent, and 200 kg water. After all materials are prepared, the above components are mixed and stirred in a forced mixer for 2.5 minutes to obtain the ultra-high performance concrete of this embodiment. The concrete exhibits excellent workability and exhibits no segregation or bleeding.

[0033] Example 2:

[0034] An ultra-high performance concrete containing volcanic rock powder has the following components per cubic meter: 750 kg cement, 40 kg silica fume, 550 kg volcanic rock powder, 1800 kg manufactured sand, 35 kg water-reducing agent, and 195 kg water. After all materials are prepared, the above components are mixed and stirred in a forced mixer for 3 minutes to obtain the ultra-high performance concrete of this embodiment. The concrete exhibits excellent workability and exhibits no segregation or bleeding.

[0035] Example 3:

[0036] An ultra-high performance concrete containing volcanic rock powder has the following components per cubic meter: 700 kg cement, 50 kg silica fume, 500 kg volcanic rock powder, 2000 kg manufactured sand, 25 kg water-reducing agent, and 205 kg water. After all materials are prepared, the above components are mixed and stirred in a forced mixer for 5 minutes to obtain the ultra-high performance concrete of this embodiment. The concrete exhibits excellent workability and exhibits no segregation or bleeding.

[0037] Comparative Example 1:

[0038] An ultra-high performance concrete that does not contain volcanic rock powder has the following components per cubic meter: 750 kg cement, 45 kg silica fume, 275 kg fly ash, 275 kg slag powder, 1960 kg manufactured sand, 33 kg water-reducing agent, and 200 kg water. After all materials are prepared, the above components are mixed and stirred in a forced mixer for 3 minutes to obtain the ultra-high performance concrete of this comparative example.

[0039] The expansion of Examples 1-3 and Comparative Example 1 was tested according to GB / T 8077-2000 standard, the 28-day compressive strength of Examples 1-3 and Comparative Example 1 was tested according to GB / T 50081-2002 standard, and the 28-day drying shrinkage of Examples 1-3 and Comparative Example 1 was determined according to GB / T 50092-1996 standard. The results are shown in Table 1.

[0040] Table 1 Test Results

[0041]

[0042] Table 1 shows that the ultra-high performance concrete made by replacing commonly used mineral admixtures such as volcanic rock powder and fly ash with volcanic rock powder has good workability and mechanical properties. Furthermore, the volcanic rock powder particles possess a large number of micropores (such as...) Figure 1-3 As shown, this gives it excellent water retention properties, which can effectively reduce the drying shrinkage of concrete and reduce the generation of concrete cracks when used in ultra-high performance concrete.

[0043] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A type of ultra-high performance concrete containing volcanic rock powder, characterized in that, It includes the following components by weight: 700-750 parts cement, 40-50 parts silica fume, 500-550 parts volcanic rock powder, 1800-2000 parts manufactured sand, 25-35 parts water-reducing agent, and 195-205 parts water. The specific surface area of ​​the volcanic rock powder is ≥500 m². 2 / kg, loss on ignition ≤1.5%; The volcanic rock powder has a particle size distribution of 0.3~240μm, a micropore distribution of 5~140nm, and a 28d activity index ≥105%, and is used to reduce the drying shrinkage of concrete. The ultra-high performance concrete has a 28-day compressive strength ≥140MPa.

2. The ultra-high performance concrete containing volcanic rock powder according to claim 1, characterized in that, The cement is silicate cement, and the standard consistency water content of the cement is ≤26%.

3. The ultra-high performance concrete containing volcanic rock powder according to claim 1, characterized in that, The particle size distribution of the silica fume is 200-1000 nm.

4. The ultra-high performance concrete containing volcanic rock powder according to claim 1, characterized in that, The manufactured sand has a fineness modulus of 2.7 to 3.0, a stone powder content of ≤3%, and a clay lump content of ≤0.5%.

5. The ultra-high performance concrete containing volcanic rock powder according to claim 1, characterized in that, The water-reducing agent is a liquid polycarboxylate-based water-reducing agent.

6. The ultra-high performance concrete containing volcanic rock powder according to claim 5, characterized in that, The water-reducing agent has a solid content between 35% and 45 wt% and a water reduction rate of not less than 30%.

7. A method for preparing ultra-high performance concrete containing volcanic rock powder as described in any one of claims 1-6, characterized in that, The process includes the following steps: mixing the components in proportion and mechanically stirring for 2-5 minutes to obtain the ultra-high performance concrete.

8. The application of the ultra-high performance concrete containing volcanic rock powder as described in any one of claims 1-6 as a high-strength building material.

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