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Process of making manhole cover of chemical pre-stressed steel fiber reinforced concrete

A technology of steel fiber concrete and fiber concrete, applied in water conservancy projects, artificial islands, underwater structures, etc., can solve structural cracking, low concrete flexural strength, manhole cover crack resistance, impact resistance, poor fatigue resistance, etc. question

Inactive Publication Date: 2004-03-10
嘉兴学院土木工程研究所
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] In the prior art, the manufacturing method of the steel fiber concrete manhole cover is to put the prepared steel fiber concrete into the steel coaming and form it by vibration, after 12 to 72 hours of parking, demoulding, and then natural curing for 7 to 28 days , the inner side of the steel hoarding is welded and fixed with reticular reinforcing steel bars; ordinary Portland cement is commonly used in concrete, because no prestress is applied in the structure, and the flexural strength of concrete itself is low. As a result, the crack resistance, impact resistance and fatigue resistance of the manhole cover are poor, and it is easy to cause the structure to crack in advance under the repeated action of a relatively large frequency of vehicle load after the manhole cover is laid, thereby reducing the bearing capacity of the structure and shortening the life of the manhole cover. Service life of manhole cover

Method used

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Examples

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Comparison scheme
Effect test

Embodiment 1

[0028] Example 1: UEA concrete expansion agent is used to replace 15% of ordinary Portland cement with a strength grade of 42.5, and a chemically prestressed steel fiber concrete with a steel fiber volume ratio of 1.5% is prepared. The prepared steel fiber The concrete is placed in the steel hoarding and shaped by vibration. After one day of natural curing, it is demoulded, placed in the finished product yard, watered twice a day, and cured for 28 days before leaving the factory. According to the JC889-2001 "Steel Fiber Concrete Inspection Manhole Cover" standard, the manhole cover was tested: after adding 15% UEA concrete expansion agent, the concrete strength of the manhole cover increased by 5.3%, the crack load increased by 28.7%, and the failure load increased by 2.7%. .

Embodiment 2

[0029] Example 2: Use 42.5-grade alunite expansive cement to replace ordinary Portland cement with a strength grade of 42.5, and at the same time add 1.5% volume ratio of steel fibers to prepare chemically prestressed steel fiber concrete. It is required to set up the steel skeleton of the manhole cover, then put in fresh concrete, form it by vibration, and demould after one day of natural curing. Place the manhole cover after demoulding in a pool maintained at normal temperature for 5 days, then stack it to the finished product yard, sprinkle water twice a day, and leave the factory after 28 days. The mechanical properties of the manhole cover are tested: the concrete strength of the manhole cover is increased by 7.1%, the crack load is increased by 31.5%, and the failure load is increased by 3.6%.

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Abstract

In the present invention prepared steel fiber reinforced concrete is filled into steel enclosure with reinforcing steel bar net inside and through vibration to form, letting stand for 12-72 hr, demolding and curing for 7-28 days, the manhole cover is produced. The cement in the concrete is self-stressed expanding cement or Portland cement added with concrete expanding agent. Owing the self-expanding stress or chemical prestress, the said manhole cover has raised breaking resistance and long service life.

Description

technical field [0001] The invention relates to a manufacturing method of a well cover. Background technique [0002] In the prior art, the manufacturing method of the steel fiber concrete manhole cover is to put the prepared steel fiber concrete into the steel coaming and form it by vibration, after 12 to 72 hours of parking, demoulding, and then natural curing for 7 to 28 days , the inner side of the steel hoarding is welded and fixed with reticular reinforcing steel bars; ordinary Portland cement is commonly used in concrete, because no prestress is applied in the structure, and the flexural strength of concrete itself is low. As a result, the crack resistance, impact resistance and fatigue resistance of the manhole cover are poor, and it is easy to cause the structure to crack in advance under the repeated action of a relatively large frequency of vehicle load after the manhole cover is laid, thereby reducing the bearing capacity of the structure and shortening the life ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B28/04
CPCC04B28/04
Inventor 蒋元海
Owner 嘉兴学院土木工程研究所
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