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Low-viscosity, anti-cracking and high-strength wet-spraying concrete and preparation method thereof

A high-strength technology of wet shotcrete, which is applied in the field of low-viscosity crack-resistant high-strength wet shotcrete and its preparation, can solve the difficulties in meeting the needs of rapid support of cavern structures, increasing the amount of sprayed concrete cementitious materials, and difficult to meet pumping requirements. In order to achieve the effect of reducing the risk of cracking, good construction performance and expanding the spacing

Active Publication Date: 2018-10-02
NANJING HYDRAULIC RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Reducing the water-binder ratio and adding highly active cementitious materials are the two main means to improve the strength of shotcrete, but this will cause two problems: first, the viscosity of the concrete will increase, and the flow resistance will increase, making it difficult to meet the requirements during the construction process. Pumping and injection requirements, prone to accidents such as pipe blockage
Second, low water-binder ratio will increase the amount of cementitious materials in shotcrete, which will increase the adverse shrinkage and deformation, and increase the risk of concrete cracking
[0017] The above-mentioned anti-cracking (shrinkage compensation) shotcrete has a strength grade of C25~C30 (25MPa~38.2MPa), which is difficult to meet the rapid support requirements of cavern structures under high ground stress conditions
None of the above-mentioned high-strength shotcrete mentions viscosity reduction and anti-cracking measures

Method used

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  • Low-viscosity, anti-cracking and high-strength wet-spraying concrete and preparation method thereof
  • Low-viscosity, anti-cracking and high-strength wet-spraying concrete and preparation method thereof
  • Low-viscosity, anti-cracking and high-strength wet-spraying concrete and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0058] The composition ratio of the materials is shown in Table 1.

[0059] Table 1 The base mix ratio (kg / m) of the anti-cracking component and the viscosity adjusting component 3 )

[0060]

[0061] The water-binder ratio of the wet sprayed concrete is 0.35, the cement used is P O42.5, the mineral powder is S95 grade, nano-SiO 2 The volume average particle diameter D (4,3) The sand is machine-made sand with a fineness modulus of 2.8, the stone is artificial gravel of 5mm to 10mm, the water reducing agent is a high-performance water reducing agent with a water reducing rate of 28%, and the non-alkali liquid quick-setting agent has a compressive strength of 28d The ratio is 124%. Cement, nano-SiO in cementitious materials 2 The mixing ratio of mineral powder and slag is 90:5:5, and anti-cracking and viscosity-reducing measures are not used. It is used as the base mixing ratio, and the number is 1.

Embodiment 2

[0063] The composition ratio of the materials is shown in Table 2.

[0064] Table 2 The base mix ratio (kg / m 3 )

[0065]

[0066] The water-binder ratio of the wet sprayed concrete is 0.35, the cement used is P O42.5, the mineral powder is S95 grade, nano-SiO 2 The volume average particle diameter D (4,3) The sand is 73nm, the sand is machine-made sand with a fineness modulus of 2.8, the stone is artificial gravel of 5mm to 10mm, the water reducing agent is a high-performance water reducing agent with a water reducing rate of 28%, and the non-alkali liquid quick-setting agent has a compressive strength of 28d The ratio is 124%. Cement, nano-SiO in cementitious materials 2The mixing ratio of mineral powder and mineral powder is 79:10:11. The mixing ratio of the expansion component, the internal maintenance component and the hybrid synthetic fiber in the anti-cracking component is 60:1:16, and the expansion component used is a modified rosin resin acid-coated calcium ox...

Embodiment 3

[0068] The composition ratio of materials is shown in Table 3.

[0069] Table 3 The basic mixing ratio (kg / m) of adding viscosity adjustment components and not mixing anti-cracking components 3 )

[0070]

[0071] The water-binder ratio of the wet sprayed concrete is 0.35, the cement used is P·O 42.5, the mineral powder is S95 grade, nano-SiO 2 The volume average particle diameter D (4,3) The sand is 75nm, the sand is machine-made sand with a fineness modulus of 2.8, the stone is artificial gravel of 5mm to 10mm, the water reducing agent is a high-performance water reducing agent with a water reducing rate of 28%, and the non-alkali liquid quick-setting agent has a compressive strength of 28d The ratio is 124%. Cement, nano-SiO in cementitious materials 2 The mixing ratio of mineral powder and mineral powder is 85:8:7. Added a certain amount of viscosity adjusting components, the viscosity adjusting components are methallyl alcohol ether, sodium methacrylate, alkoxy po...

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Abstract

The invention discloses low-viscosity, anti-cracking and high-strength wet-spraying concrete and a preparation method thereof. The wet-spraying concrete comprises the following components: 470-485kg / m<3> of a cementing material, 165-175kg / m<3> of water, 5-11kg / m<3> of a viscosity regulating component, 38.5-40.5kg / m<3> of an anti-cracking component, 8.0-8.5kg / m<3> of a water reducing component, 900-950kg / m<3> of fine aggregate, 750-780kg / m<3> of coarse aggregate and 40-42kg / m<3> of an alkali-free liquid accelerator. The wet-spraying concrete has 28d compressive strength of 65MPa or above; undera slump condition of 200mm plus or minus 10mm, the emptying time of an inverted slump cone is shorter than 15s; in an early anti-cracking test, the total cracking area per unit area is not greater than 250mm<2> / m<2>, and the cracking grade is L-IV; in a ring cracking test, no cracking occurs within 56d, and the cracking tendency is low. The wet-spraying concrete is high in strength, low in viscosity, good in anti-cracking performance and easy to pump and construct through spraying, and facilitates improvement on the bearing capacity and the water-proof performance of a sprayed concrete liningstructure.

Description

technical field [0001] The invention belongs to the technical field of support materials for underground spaces, and in particular relates to a low-viscosity crack-resistant high-strength wet shotcrete and a preparation method thereof. technical background [0002] The anchor shotcrete system formed by the combination of anchor rod and shotcrete plays an important role in the support of underground space. It can reduce the relaxation of surrounding rock, exert the self-stabilization ability of surrounding rock, and improve the timeliness and stability of support. However, with the in-depth development of the western region, the number of tunnels with large buried depths and long distances has increased, and the problem of high ground stress has become prominent. Taking the underground powerhouse caverns of Jinping I Hydropower Station as an example, the measured ground stress at 16 measuring points is as high as 20.0MPa~35.7MPa. Unfavorable engineering geological disasters ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B28/04C04B111/34
CPCC04B28/04C04B2111/00155C04B2111/00724C04B2111/00732C04B2111/343C04B2201/50C04B14/062C04B18/141C04B14/06C04B14/02C04B2103/302C04B2103/12C04B20/0076C04B22/064C04B24/34C04B24/24C04B16/0625C04B16/0633C04B24/023C04B24/04C04B24/2647C04B22/14C04B24/16
Inventor 宁逢伟白银蔡跃波陈波丁建彤张丰
Owner NANJING HYDRAULIC RES INST
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