JPS613745A - Cement mortar lining iron pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cement mortar lined its pipe.

The inner surfaces of iron pipes used for water and sewage pipes, industrial water pipes, etc. are lined with mortar, mainly made of Portland cement, for corrosion prevention purposes. The mortar lining method uses centrifugal force in the case of straight pipes.
In the case of irregularly shaped tubes, this is usually done using a trowel, centrifugal projection method, or opening. Therefore, the unhardened mortar used in lining construction must have appropriate fluidity, enough stickiness to prevent the part applied to the upper inner surface of the iron pipe from peeling off or falling off, and flexibility to withstand the vibrations that occur during transportation to the curing room. Ru. In addition to the above, the cured mortar μ is required to have early strength, adhesion to the surface of iron pipes, water resistance, crack resistance (no cracking), chemical resistance, etc. However, the conventional mortar mainly composed of l/L/trand cement cannot fully satisfy the above performance, and is used immediately after lining, after mortar curing, or at piping construction sites, etc. There were defects such as peeling, falling off, cracking, splitting, and chipping. These defects often occur on the end face of large-diameter iron pipes that are subject to large strain due to their own weight. Therefore, during a water pressure test of the steel pipe, water penetrated through the defective part and the water pressure did not rise, making it impossible to perform the water pressure test. I failed the exam.

These defective I-lined pipes were mortar-lined again after the entire surface of the μ section or the defective portion was removed. Therefore, much effort was required for removal work and repair work.

The present invention relates to a cement mortar lined iron pipe that reduces the defects described above.

The present invention uses a cement mortar-lined iron pipe in which cement mortar μ obtained by blending acrylic-styrene copolymer emuldigon with cement is coated on the inner surface of the iron pipe.

The acrylic-styrene copolymer emulsion used in the present invention is a copolymerized emulsion of styrene and acrylic ester in an arbitrary ratio, and has a particle size of 0.5 μm or less, a solid content of about 50%, and a viscosity of 100%. ~10n 0cpv25℃
, a resin emulsion with a pH of 7.0 to 9.0, required (
(Depending on the situation, compositions modified with dispersants made of anionic or nonionic surfactants, antifoaming agents, antifreeze agents made of ethylene glycol or organic solvents, film-forming accelerators made of various plasticizers, etc.) may also be used. included.

Cement-based mortar means one in which 5 times the amount of aggregate is added to cement. Cement here refers to hydraulic cement such as Portland cement.
Includes Portland yarn, mixed cement system, and special cement system. Portland type is normal Portland cement,
These include early-strength Portland cement, ultra-early strength Portland cement, white Portland cement, oil well cement, and sulfate-resistant cement. In addition, mixed cement systems include blast furnace cement, silica cement, and fly ash cement, and special cement systems include aluminum cement, expansive cement, color cement, and jet cement. Next, the amount of the acrylic-styrene copolymer emulsion to be added is 0.1 to 0.1 to the solid weight equivalent to the above cement.
0.3 parts is suitable. That is, if it is less than 0.1 part, the effect of the present invention cannot be obtained, and if it is more than 0.3 part, the water resistance decreases and is not suitable. Further, the amount of water added is arbitrarily determined based on the amount of aggregate to cement, the amount of acrylic-styrene copolymer emulsion m7 added, etc., so as to provide suitable flow characteristics.

The present invention uses acrylic-styrene copolymer emulsilon, which has a higher viscosity than water, compared to conventional cement-aggregate-water system mortar, so the uncured mortar itself has viscosity and flexibility. No peeling or falling off even immediately after lining. Similarly, it can withstand vibrations generated during transportation to the curing room. Additionally, the amount of water in the mortar can be reduced. In other words, the amount of water required to maintain a constant softness (flow value) K that does not interfere with application work, even if the sum of the water contained in the 75ζ emuldigon and the water added later, can be much smaller than with conventional mortar. It is.

In other words, there is less excess water that does not participate in the hardening of the cement, and a mortar A/W with a dense structure can be obtained after hardening. Furthermore, since the water retention property is increased, the contact area and surface with the iron pipe are less likely to dry out (and the adhesion (adhesive strength) to the iron pipe is significantly improved without creating a brittle layer. The resin (acrylic-styrene copolymer resin) that exists between the crystals or aggregate increases mutual bonding strength, prevents water and carbon dioxide from entering, and prevents heat generated between the iron pipe and the mortar layer due to temperature changes. It absorbs the strain caused by differences in expansion coefficients and deformation during movement.These interactions improve the adhesion, water resistance, deformation followability, and durability of the mortar lining layer.Therefore, immediately after mortar lining , part or all of the mortar lining layer peels off or falls off, or cracks or splits occur during steam curing or during transportation to a piping construction site, etc.
The rate of occurrence of chipping is significantly lower in the method of the present invention than in the conventional method.

It should be noted that methods of improving cement mortar by adding various thermoplastic resin emulsions or various synthetic rubber latexnes have also been proposed, but in terms of water resistance, etc., the improvement by the acrylic-styrene copolymer emulsion of the present invention cannot be achieved. do not have.

Next, the present invention will be explained by examples.

Example 1 and Comparative Example 1 Portland cement, sand, acrylic-styrene copolymer emulsion (solid content 50%, viscosity 6°cps/25°C
, PH 8,6'> (AS emulzidinone and water were self-combined to make the mortar of Example 10. Also, the mortar without AS emulsion was the mortar of Comparative Example 1. These mortar compositions and flow values are shown in Table 1.

Next, mortar lining was applied to the V-shaped cast iron straight pipe (duct tie of fi 250M) using a known method using a rapid core force. Approximately 2
After leaving it for an hour, steam curing it for about 15 hours, and then for another 1 hour.
It was left outside for several months to cure and then transported by truck to the piping site. After steam curing, after outdoor curing, and at each point in time at the piping site, the cumulative total of defective pipes (cracks or chips are determined by second-visual observation. Peeling between iron pipes and mortar Wt: by hammering test using a small mallet). It is shown in Table 2.

As is clear from the table, the cumulative defective rate is 50% using the conventional method.
On the other hand, in the present invention, it was significantly reduced by 10%.

Claims (2)

[Claims] (1) A cement mortar-lined iron pipe characterized by coating the inner surface of the iron pipe with a cement-based mortar obtained by blending an acrylic-styrene copolymer emulsion with cement. (2) The amount of the acrylic-styrene copolymer emulsion added is 0.1 to 0.0 in terms of solid weight relative to cement.
The cement mortar-lined iron pipe according to claim 1, characterized in that three parts of cement-based mortar are applied to the inner surface of the iron pipe.