JPH0765700B2 - Water lining pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a cement mortar lining pipe such as a steel pipe and a cast iron pipe supplied for water supply, and more specifically, an object thereof is to suppress the pH rise of tap water. Regarding water lining pipes.

[Conventional technology and its problems]

Conventionally, as this type of lining pipe, a steel pipe / cast iron pipe, which has been subjected to centrifugal lining and then steam-cured, has been used in which ordinary Portland cement or expansion cement is used as a binder. However, when running domestic water such as drinking water or industrial water like tap water, there was a problem that the alkali in the cement mortar was eluted and the pH of tap water increased. If alumina cement mortar is used as a countermeasure against this, the pH rise can be suppressed to some extent, but it has not been sufficiently satisfactory.

As a result of various studies by the present inventor to eliminate the above-mentioned drawbacks,
After lining the alumina cement mortar to the steel pipe and cast iron pipe, we obtained the finding that it is sufficient to use a water supply lining pipe in which the contact surface of the lining layer with tap water is carbonated,
The present invention has been completed.

[Means for solving problems]

That is, the present invention is a lining pipe for water supply, which has a carbonation layer on the contact surface of the lining layer of cement mortar containing calcium aluminate as a main component with tap water.

The details of the present invention will be described below.

The cement containing calcium aluminate as the main component used in the present invention means CA, CA ₂ , C _{3 where} CaO is C and Al ₂ O ₃ is A.
A and C ₁₂ A _{7 and the} like, which is a hydraulic substance containing at least one of the calcium aluminates as a main component,
Alumina cement is usually used.

Alumina cement (hereinafter referred to as AC) is a tube mill, vibration mill, and roller mill that uses clinker synthesized by a firing method and / or an electrofusion method using an alumina source such as bauxite or Bayer alumina and a calcia source such as quicklime or limestone. It is crushed with a crusher such as.

The sand used for AC mortar can be sea sand, mountain sand, river sand, etc. If necessary, admixtures such as gypsum and slaked lime, and set retarders such as carboxylic acids and sulfonic acids may be used in AC mortar.

The lining is performed by centrifugal molding, and it is preferable that the lining is performed with a centrifugal force that does not cause aggregate separation in AC mortar.

After lining, to provide a carbonized layer on the contact surface of the lining layer with tap water (hereinafter referred to simply as the contact surface), leave it in the presence of carbon dioxide gas for a long time or use carbonated water with dry ice etc. The method of carbonation is not particularly limited.

The thickness of the carbonation layer is preferably 0.1 to 2 mm, more preferably 0.2 to 1 mm. When the carbonation layer exceeds 2 mm, peeling is likely to occur due to running water, and when it is less than 0.1 mm, the pH increase cannot be sufficiently suppressed, which is not preferable. The thickness of the carbonation layer in the present invention is the thickness from the contact surface up to where neutral (pH = 7) is exhibited by coating the cut surface of the lining tube with phenolphthalein.

〔Example〕

 Next, the present invention will be further described with reference to Examples.

Example 1 100 parts by weight of AC (alumina cement No. 2: manufactured by Denki Kagaku Kogyo), 200 parts by weight of sand (2.5 mm below river sand) and 50 parts by weight of water were kneaded with a mortar mixer to prepare AC mortar.

While rotating this AC mortar into a steel pipe with an inner diameter of 100 mm, a length of 500 mm and a thickness of 5 mm at 200 rpm while throwing it up to a thickness of 5 mm and smoothing the surface, the rotation of the steel pipe is increased and high speed compaction at 800 rpm is performed.
I went for a minute. After that, stop the rotation, drain the lining surface, remove the leitance part with a brush, perform high-speed compaction again, and then perform steam curing at 45 ° C / 4Hr, AC
A mortar lining tube was made.

Further, this lining pipe was left in carbon dioxide gas to prepare a lining pipe having a carbonation layer of a predetermined thickness, and the physical properties of the material on the 7th day of age were measured. The results are shown in Table-1.

The physical properties were measured by the following methods.

(1) pH: After washing the pipe with water on the 7th day to remove the scale, soak it in running water of 6 m / sec for 1 hour, drain it, and fill it with distilled water for 24 hours. The variation was measured.

(2) Peeling: On the 7th day of age, the pipe was washed with water to remove the scale, and the peeling after immersing in running water of 20 m / sec for 24 hours was visually observed.

As shown in Table 1, when the water supply lining pipe of the present invention is used, a rise in pH of tap water can be sufficiently suppressed and peeling due to running water does not occur.

〔The invention's effect〕

By using the lining pipe for water supply of the present invention, it is possible to suppress an increase in pH of tap water, and it is possible to supply drinking water having no bitterness especially when used for a water supply pipe.

Claims (1)

[Claims] 1. A lining pipe for water supply, which has a carbonation layer on the contact surface of the lining layer of cement mortar containing calcium aluminate as a main component with tap water.