JPS5825569B2 - Lining method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lining method that can suppress the amount of laitance that occurs when lining the inner surface of a metal pipe (mainly a cast iron pipe or steel pipe) rotating at a low speed with a gravity multiple of 10 or less with cement mortar. It is.

Conventionally, in order to line the inner surface of an iron pipe with cement mortar, ordinary cement mortar is spread evenly on the inner surface of the lining pipe, and then the pipe is usually rotated at a high speed with a gravity multiple of 20 or more to firmly centrifugally press the mortar onto the inner surface of the pipe. A method has been adopted.

However, in order to apply such a high centrifugal force to a particularly large-diameter pipe, it is complicated to install reinforcing tires to prevent the iron pipe from bending, and noise pollution problems arise.

To solve this problem, a method has been proposed that uses commercially available ultra-early strength cement (product name: Jet Cement) and centrifuges it at low speed, but this method results in the formation of a large amount of laitance in the mortar layer after lining. New problems arose in that the layer became soft and easily peeled off even if the surface was polished and a seal coat agent was applied, and a large amount of laitance had to be treated during polishing.

The inventor of the present invention has completed the present invention as a result of intensive research to solve this problem. Choreographing a cement mortar containing a cement quick-setting agent as the main component and alkyl cellulose in an amount of 0.05 to 0.5% by weight based on the cement.
It is centrifugal.

The present invention will be explained in detail below.

The cement quick setting agent used in the present invention is composed of calcium aluminate and gypsum, and the calcium aluminate includes 3CaO-A1203, CaO・Al2O
3,12CaO・7A1203, 11Ca0・7A1203・CaF2. 3Ca0, 3A1203, CaF2, etc. are used,
Among these, amorphous materials having these compositions are preferred from the viewpoint of strength development and laitance suppression effect.

In addition, the ratio of gypsum to this is preferably in the range of 0.3 to 2 times by weight; if the amount of gypsum is too small than this, the cement mortar will set rapidly and become unstable, and if it is too much more than this, the cement mortar will become unstable. Strength development deteriorates.

Also, calcium aluminate CaO/A 120
s If the weight ratio is small, the amount of gypsum may be increased, and if the nucleation is large, the opposite may be the case.

Furthermore, although any form of gypsum may be used, insoluble anhydrite (anhydrite) is the most preferable from the viewpoint of strength development and suppression of laitance generation, and if rapid setting is a problem, anhydrite may be used. It is best to use it in combination with hemihydrate gypsum or known letter goo.

The fineness of the cement quick setting agent having such a composition is preferably 4,000 to 8,000 ca/t in Blaine value, and the amount thereof added to the cement is preferably about 3 to 20% by weight.

The cement quick-setting agent can be used by mixing it with cement in advance, or by feeding the cement quick-setting agent slurry and mortar slurry separately and mixing them just before lining.
A so-called 1.5 shot method can be used.

Alkylcellulose is an essential component for suppressing laitance generation, and even if Poval, which is a water-soluble polymer substance of the same quality, is used, the effect will not be expressed.

The ratio of alkyl cellulose to cement is 0.05
The amount is 0.5% by weight, and if the amount is less than this, there will be no effect of suppressing laitance, and if the amount is too much, the fluidity of the mortar will decrease, making it impractical.

As the alkyl cellulose, methyl cellulose, ethyl cellulose, etc. can be used, but methyl cellulose is preferred from the viewpoint of availability.

The use of alkyl cellulose causes some foaming, which makes work difficult, but if this becomes a problem, it is desirable to use a commercially available antifoaming agent such as a silicone type or nonionic type.

As a method for adding alkyl cellulose, it is preferable to mix it in powder form with cement or a cement quick setting agent in advance.

Further, it is possible to add a commercially available cement expansion agent, fly ash, silica, or other bulking agent to the cement mortar.

According to the method of the present invention, even when lining is performed at a low speed with a gravity multiple of 10 or less, the occurrence of laitance in the mortar layer is small;
Furthermore, even if a seal coat is applied after polishing, it does not peel off.

The present invention will be explained below with reference to Examples.

Example Ordinary Portland cement 2.35 to 9, fly ash 0.41 kg, cement expansion agent (Denki Kagaku Kogyo product name Denka CSA #20) 0.24 kg, natural sand 7
．． 50 kg of methylcellulose (Shin-Etsu Chemical Co., Ltd. splitting product name Metrose 8000) 3S' and 1.35 kg of water were mixed in a mortar mixer, and this was mixed with CaO/Al2O3.
Cement quick-setting agent 240 with a play value of about 6000 cvi/fl, which is a mixture of equal weight of insoluble anhydrite to amorphous calcium aluminate with a weight ratio of 1.21 or 0.56.
1. Water 1201, citric acid 3g, potassium carbonate 9g and nonio antifoaming agent (San Nopco ■ PD-1) 1.5f
A slurry containing the above was added, and the two were thoroughly mixed to produce a rapid-setting mortar.

The flow value of this mortar according to JISR5201 is 17
It was 0m7W.

Next, the mortar was sprinkled on the inner surface of an iron pipe with an inner diameter of 255% and a length of 500X to a thickness of 13%, and the gravity multiplier was 5.
Centrifuged for 15 minutes at
℃, gelation occurred 11 minutes after crosstalk).

After the lined tube was left indoors for a day and night, the amount of laitance generated on the lined surface was measured by scraping off the soft layer with a spoon.

As a result, the weight ratio of CaO/Al2O3 using amorphous calcium aluminate of 1.21 was 0.40?
/25cd, and the one using the one with nucleation of 0.56 is 0.21? It was 725c4.

Furthermore, a vinyl chloride seal coat material was applied to the scraped surfaces of both lining layers, and the adhesion state was observed one month later, but neither peeled off.

For comparison, a mortar layer lined in the same manner without the addition of methyl cellulose and antifoaming agent was measured, and the mortar layer using amorphous calcium aluminate with a CaO/Al2O3 weight ratio of 1.21 was 1.13 f? 7
25c4, and the one with a nucleation of 0.56 was 0.321t725c4.

Similarly, when the seal coat material was applied and the adhesion state was measured, the former material (with nucleation of 1.21) was easily peeled off with a fingernail, but the latter material was good.

Claims (1)

[Claims] 1. On the inner surface of a metal tube rotating at a low speed with a gravity multiple of 10 or less,
When applying the cement mortar, a cement mortar containing a cement quick-setting agent mainly composed of calcium aluminate and gypsum and alkyl cellulose in an amount of 0.05 to 0.5% by weight based on the cement is used. A method for lining the inner surface of metal tubes. 2 Claims that use a cement mortar in which the cement quick-setting agent has a weight ratio of insoluble anhydrite to amorphous calcium aluminate of 0.3 to 2, and 3 to 20% by weight of this to the cement. The lining method according to item 1. 3. The running method according to claim 1 or 2, wherein the alkylcellulose is methylcellulose.