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Nanoscale shotcrete modified admixture

A technology of sprayed concrete and admixtures, applied in the field of concrete admixtures

Active Publication Date: 2014-10-22
NANJING HYDRAULIC RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Nanomaterials have been widely used in high performance concrete [2,3], but as a New admixtures for modifying the specific properties of shotcrete (rebound rate, setting time, primary spray layer thickness) are rarely reported

Method used

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  • Nanoscale shotcrete modified admixture
  • Nanoscale shotcrete modified admixture

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Embodiment 1, nanoscale shotcrete modified admixture mass consists of:

[0030] nano-SiO 2 : 82.5 copies;

[0031] Fly ash: 10 parts;

[0032] Naphthalene-based surfactant: 7.5 parts.

[0033] The dosage of the modified admixture of nano-scale shotcrete is 10% of the cement mass, and the dosage of the quick-setting agent is 8% of the total mass of the cement and the nano-admixture, which are added at the nozzle. Concrete spraying is carried out by wet spraying process. The shotcrete mix ratio is as follows:

[0034] Mixing ratio of sprayed concrete with nano admixture

[0035]

[0036] The setting time of the sprayed concrete is 90s, the rebound rate is 6.0%, and the thickness of the sprayed layer is 50cm.

Embodiment 2

[0037] Example 2. The mass composition of nano-scale sprayed concrete modified admixture is:

[0038] nano-SiO 2 : 62.5 copies;

[0039] Fly ash: 10 parts;

[0040] Zeolite powder: 20 parts;

[0041] Naphthalene-based surfactant: 7.5 parts.

[0042] Concrete mix ratio, spraying process are the same as Example 1. The setting time of the sprayed concrete is 95s, the rebound rate is 6.5%, and the thickness of the sprayed layer is 45cm.

Embodiment 3

[0043] Embodiment 3, nanoscale shotcrete modified admixture mass consists of:

[0044] nano-SiO 2 : 62.5 copies;

[0045] Fly ash: 10 parts;

[0046] 20 parts of metakaolin;

[0047] Naphthalene-based surfactant: 7.5 parts.

[0048] Concrete mix ratio, spraying process are the same as Example 1. The setting time of the shotcrete is 88s, the rebound rate is 6.0%, and the thickness of the sprayed layer is 55cm.

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Abstract

The invention relates to a nanoscale sprayed concrete modified-admixture, which comprises the following components in parts by weight: 60-95 parts of nano SiO2, 5-40 parts of ultrafine mineral admixture and 0-10 parts of surfactant, wherein the nano SiO2 is a high-activity nano-particle materials of which the SiO2 content is at least 95 percent. The volume mean diameter D (4 and 3) of powder particles of the nanoscale sprayed concrete modified-admixture is at most 150 nm. The ultrafine mineral admixture is prepared from one or several of coal ash, zeolite powder, metakaolin and slag powder, and the surfactant is prepared from one of organic powder of polycarboxylic acids, naphthalenes, aliphatics, sulfamates and the like. The admixture is mixed into a sprayed concrete mixture according to 5-15 percent of mass of cement. Through the nanoscale sprayed concrete modified-admixture, the rebound ratio of the wet sprayed concrete can be at most 8 percent, the setting time can be at most 2 minutes, and the thickness of one-step spray coating is at least 35 cm.

Description

technical field [0001] The invention relates to a concrete admixture, in particular a modified admixture for nano-scale shotcrete, which is used for reducing the rebound rate of the shotcrete, shortening the setting time and increasing the thickness of the primary sprayed layer. Background technique [0002] During tunnel construction, in order to ensure construction safety, reduce tunnel surrounding rock relaxation, timely control the development of ground pressure, and more importantly, to control the reduction of surrounding rock self-supporting ability, so as to make full use of the surrounding rock's own self-supporting ability, Usually shotcrete is used for primary support. [0003] In order to give full play to the supporting effect of shotcrete, it must be done: the shotcrete is closely attached to the surrounding rock, that is, the bonding strength with the surrounding rock is high; after the excavation of the tunnel, it is hoped that the surrounding rock can be con...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B14/04
Inventor 陈波丁建彤蔡跃波白银宁逢伟
Owner NANJING HYDRAULIC RES INST