JPH01316596A - Corrosion resisting mortar-lined tube - Google Patents

Abstract

PURPOSE:To have a tube with good acid resistance and also simplify the process of corrosion resisting tube manufacture by lining a concrete tube or the like with a specifically combined mortar composition which includes specific emulsions of synthetic high polymer. CONSTITUTION:The inner surface and the outer surface of a concrete tube or the inner surface of a mortar-lined cast iron tube are lined with a mortar composition composed of (a) 20-40% by weight of Portland ciment, (b) 30-50% by weight of aggregate, (c) 3-8% by weight of silica, (d) 10-20% by weight of high polymeric emulsion of epoxy resin (solid portion of resin) and (e) 10-20% by weight of water.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to concrete pipes, mortar lined cast iron pipes,
Or regarding pipes with improved corrosion resistance on the concrete surface of mortar-lined steel pipes, especially corrosion-resistant mortar-lined pipes suitable for water supply, sewerage, industrial water supply, or seawater plant piping that are often installed outdoors or underground. It is.

[Prior Art] Typical concrete pipes, such as centrifugal reinforced concrete pipes, which are usually called Huum pipes, mortar-lined cast iron pipes, and mortar-lined steel pipes, all use centrifuges rotated by a motor 1 as shown in Figure 1. A pre-assembled cylindrical formwork 3 is placed on the wheels 2, and while the formwork 3 is rotating, ready-mixed concrete 4 is poured into it, and excess water is squeezed out using a centrifugal process. Force compaction is carried out, followed by constant temperature rise and steam curing at a maximum temperature of 65°C for about 6 hours.

Centrifugal reinforced concrete pipes are cooled down to the outside temperature,
In particular, pressure pipes should be cured in water or by sprinkling water for about a week.
It is used as is for piping.

After steam curing, mortar-lined cast iron pipes or mortar-lined steel pipes are sealed with approximately 20 μm of vinyl or acrylic synthetic resin paint to prevent neutralization of the lining surface and to prevent erosion by sterilizing chlorine in tap water. There is.

It was developed in 1988 as a water pipe to obtain water resistance and corrosion resistance.
As disclosed in No. 170480, there is a vibrator made of mortar containing pieces of glass fiber whose inner wall is coated with resin (especially vinyl chloride resin), and inorganic materials such as concrete and asbestos buried outdoors or underground. In order to improve the corrosion resistance not only from the inside of the pipe but also from the outer circumferential side, it was used as a lining pipe.
As disclosed in No. 1, there are pipes made of concrete or the like whose inner and outer peripheral surfaces are coated with synthetic resins such as vinyl chloride resin and polyethylene resin.

[Problems to be solved by the invention] Conventional fume pipes, etc. have the following problems: ◎When concrete pipes are used for sewerage and wastewater is flowing, hydrogen sulfide gas is released due to the action of sulfate-reducing bacteria. may occur. This is oxidized to sulfuric acid by aerobic bacteria growing on damp walls in the air, and reacts with lime in the concrete to produce calcium sulfate, which is contained in the raw cement at about 8% due to the presence of moisture on the wall surface. Trilime aluminate 3CaO・A! further reacts with 1203,
Etson Gite 3, which causes expansion failure due to its good crystallinity
CaO@AlI2O3ψ3CaS0 ・32H20 is generated. Due to this mechanism, the wall surface of the air layer on the inner circumferential surface of the sewer becomes brittle due to erosion, which can lead to cracking of the concrete due to corrosion of the reinforcing steel, resulting in poor strength deterioration.

(b) If the pipe is exposed to environmental factors that promote corrosion and deterioration after being buried outdoors or underground, the pipe will erode from the outside. In particular, when a concrete pipe is buried in acidic soil or underground where seawater has entered, the strength deteriorates from the outer periphery.

(c) Conventional mortar cast iron pipes or mortar lined steel pipes require a seal coat process after steam curing, which takes a long time.

(→Conventional concrete pipes whose inner or outer circumferential surfaces are coated with a synthetic resin layer require a resin layer coating process after the concrete pipe forming and curing process, which is a complex and time-consuming process.

The present invention solves the problems listed in L, that is, it has excellent acid resistance, prevents expansion failure, cracking, and strength deterioration, and
The aim is also to simplify and shorten the process.

[Means for solving the problem] The inventor of the present invention has previously filed a patent application for patent application No. 61-3055.
By lining concrete pipes with a predetermined combination of mortar compositions containing emulsions of specific synthetic polymers filed as No. The present invention was completed by discovering that it is possible to provide a lining pipe with suitable characteristics as plant piping for water or seawater.

In other words, the gist of the present invention is that the inner circumferential surface of a concrete pipe made of concrete, reinforced concrete, or fiber-reinforced concrete, or the inner circumferential surface and outer circumferential surface of these concrete pipes, (a) 20 to 40% by weight of Portland cement
(b) Aggregate 30-50% by weight (e) Silica 3-8% by weight (d) Epoxy resin polymer emulsion (resin solid content > 10-20% by weight) (e)
A corrosion-resistant mortar lined pipe characterized in that it is lined with a mortar composition comprising 10 to 20% by weight of water.

The present invention will be explained in detail below.

The mortar composition of the present invention contains Portland cement, aggregate, activated silica, pigment, synthetic polymer emulsion, and water as essential components. As the Portland cement, ordinary Portland cement, early-strength Portland cement, white Portland cement, etc. can be used, and medium-heat, blast-furnace cement, alumina cement, and super-fast-hardening cement are also effective.

The amount of cement used is 20 to 40% by weight, and if the amount of cement is less than 20% by weight, the strength will be significantly reduced.
If it exceeds % by weight, the amount of shrinkage will increase. As the aggregate used, silica sand No. 3, No. 4, No. 5, No. 6, No. 7, etc. is generally used because this material is usually used in a thickness of 1 to 5 mm.

Powdered silica is used, but fine powder
Preferably, it is less than um. As the silica, for example, silica fume, siliceous dust, etc., which are by-products when manufacturing silicon or silicon alloys, are preferably used.

The amount of silica used is 3 to 8% by weight, which improves durability.

Effective in increasing and reducing water resistance.

However, if it is less than 3% by weight, no effect will be obtained, and if it exceeds 8% by weight, the amount of water added will increase and the fluidity of the mortar composition will deteriorate, resulting in a significant decrease in workability.

In addition, although it is not essential in this application, various pigments are mixed according to the user's request to achieve the desired color, but in the case of this mortar composition, 1 to 4% by weight of a white pigment (titanium white) is mixed. This results in a finished color similar to that of concrete pipes, etc.

Synthetic polymer emulsion (resin solid content) is 10-20
Weight% is preferable, and if it is lower than 10 yen 2%, waterproof performance/
Insufficient carbonation performance, salt damage resistance, and chemical resistance.

However, if it exceeds 20% by weight, although the performance described above is very good, the strength development of the mortar is delayed and the workability during construction becomes very poor.

The amount of water added is adjusted to 334i according to the user's work softness.

Examples of synthetic polymer emulsions include acrylic polymer emulsions, vinyl acetate polymers, emulsions, SBR polymer emulsions, ethylene-vinyl acetate polymer emulsions, styrene-acrylic polymer emulsions, and epoxy resin polymers. Although there are molecular emulsions, epoxy resin emulsions are preferred in the present invention. This epoxy resin emulsion is composed of a main resin and a curing agent, and contains the following essential components.

The main ingredient is a liquid bisphenol-based epoxy resin with an epoxy equivalent of 170 to 270, which is produced by reacting bisphenol A with a large excess of evilorhydrin in the presence of an alkali, and can be produced by a method known to those skilled in the art. It is possible.

These commercial products include Evodite EL-1, Evodite EL-2 (manufactured by Showa Kobunshi), Epicoat 80B, Epicoat 828 (manufactured by Yuka Shell Epoxy), and Evodite) Y.
D-115, Evototo Y D-117 (manufactured by Tobu Kasei), etc.

The curing agent is a water-dispersible or water-soluble polyamide amine resin. Polyamide amine resin is basically (1)
0.5 at 150 to 250°C using polymerized fatty acids, (2) polyalkylene polyamines, and (3) other modifiers.
It is obtained by reacting for up to 15 hours, if necessary under reduced pressure.

(1) Polymerized fatty acids include soybean oil, cottonseed oil, rapeseed oil,
The main component is dia-acid obtained by the Diels-Adler reaction of linoleic acid, oleic acid, etc., which are the main components of dehydrated castor oil, tall oil, linseed oil, coconut oil, safflower oil, rice bran oil, beef tallow, and Spanish mackerel oil. It contains a small amount of trimer acid and monomer acid.

(2) Polyalkylene polyamines include ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

(3) Other modifiers include ■acetic acid, caprylic acid,
Monocarboxylic acids such as stearic acid, oleic acid, benzoic acid, or oxalic acid, maleic acid.

Dicarboxylic acids such as succinic acid, mazelaic acid, diethylmalonic acid, adipic acid, isophthalic acid, and terephthalic acid, ■Glycine, β-alanine, γ-aminobutyric acid, ε
- Amino acids such as aminocaproic acid and their lactams, (1) esters of polymerized fatty acids, (2) cycloaliphatic amines such as acrylonitrile and acrylic acid esters, (2) cyclic aliphatic amines such as isophorone diamine, and (4) aromatic amines such as xylene diamine. A commercially available product of these water-dispersible or water-soluble polyamide amine resins is SDK''l.

SDK”2 (Showa Mini-Showa Kobunshi), Tomide 2
45 (manufactured by Gshikasei) Shrimp Link 3GO, Shrimp Link 38
0 (manufactured by Akzo Hemy), ADEKA Hardener EH-20
3. Adeka Hardener EH-204R, etc. can be mentioned.

The ratio of epoxy resin and polyamide amine resin varies depending on the epoxy equivalent of the epoxy resin, the amine value of the polyamide amine resin, and the polymer composition, but is 100:80 to 1.
00: About 20, but usually 100 near 0-1
00; about 40.

In the present invention, a concrete pipe is lined with the above mortar composition, and the concrete pipe to which it is applied is the inner circumferential surface or both the inner circumferential surface and the outer circumferential surface of a concrete pipe made of concrete, reinforced concrete, or fiber-reinforced concrete. This is the inner peripheral surface of a mortar-lined cast iron pipe or mortar-lined steel pipe whose inner peripheral surface is lined with cement mortar or fiber-reinforced cement mortar.

In this case, the amount of mortar composition used is 0 per application area.
．． 75 kg/nf to 7.5 kg/r+f (coating thickness, approximately 0.5 to 5 mm) is preferable, more preferably 2
kg/M to 3 kg/G (coating thickness, approximately 1.5 to 2 mm).

If it is less than 0.75 kg, the acid resistance will deteriorate in terms of water permeability, and if it exceeds 7.5 kg/c-, sagging will occur after application and before curing.

When lining the outer circumferential surface of a concrete pipe or the like with the mortar composition of the present invention, it may be applied by spray or feeder before placing fresh concrete into the formwork during wheel-type centrifugal forming during the manufacturing process. It may be applied by spray, brush or trowel before or after post-mold curing (eg wet curing). If applied after curing, make sure the outer diameter meets the standard and wait for 14 days, preferably 2 days.
It is preferable to carry out natural curing for 8 days.

In addition, when lining the inner circumferential surface of a concrete pipe or the like with the mortar composition of the present invention, after centrifugal compaction of the fresh concrete is completed in wheel-type centrifugal forming, it can be sprayed or fed with a feeder while being centrifugally formed. It may be finished to a predetermined inner diameter dimension, and may be applied by spraying, brushing, or troweling before, after, or during curing such as steam curing or wet curing. If it is applied after steam curing, it is preferable to make sure that the inner diameter conforms to the standard and to allow natural curing for 14 days, preferably 28 days.

The fibers of the fiber-reinforced concrete of the present invention include alkali-resistant glass fibers, stainless steel or steel fibers, inorganic fibers such as asbestos and rock wool, organic fibers such as polyethylene polypropylene, vinylon, aramid carbon, or bulb, or organic or inorganic fibers. This also includes items that are used in combination with various types of strings.

[Example] Examples will be described below to clarify the effects of the present invention, but the technical scope of the present invention is not limited thereto.

The mortar compositions for lining used in the examples were three types, A, B, and C listed in Table 1, and only the synthetic polymer emulsion was changed. A is the composition of the present invention, formulation B, C is for comparison, and B is a commercially available ethylene-vinyl acetate polymer emulsion (abbreviated as EvA).
, C used commercially available SBR type emulzidine (abbreviated as 5BR).

The epoxy resin polymer emulsion A is prepared in the following manner. Evodite EL-125k is added to a polyamide amine aqueous solution in which 15 kg of SDK"1 is dissolved in 60 kg of water.
g was added and stirred for 5 minutes using a hand mixer to obtain 100 kg of an epoxy resin polymer emulsion consisting of 40% epoxy resin and polyamide amine resin.

Table 1 During centrifugal forming of C-type 1500φ centrifugal force reinforced concrete pipe, before adding fresh concrete, A, B,
The mortar composition of C was applied to the inner peripheral surface of the steel formwork at a rate of 2 kg/dC.
The thickness was about 1.5 am). After that, fresh concrete was poured in and compacted, and then the mortar compositions A, B, and C mixed earlier were again poured into the inner circumferential surface using a feeder at a rate of 2 kg/dc (approximately 1.5 mm thick). After compacting and rotating for 3 minutes, steam curing and demolding,
Natural curing (approximately 20° C., approximately 65% R, H) was performed for one day. After that, use a diamond cutter to cut approximately 30cm x 30
A test piece was prepared by cutting out a 11.2 cm thick plate and sealing the cut surface with epoxy resin.
%R, H, air curing was performed for 3 weeks. Approximately 30cm x 30cm x Il, 2 pieces cut from the test piece and a commercially available centrifugal reinforced concrete pipe C type 1500φ
Adhesive strength test, corrosion resistance test using cm thick test piece,
A carbonation acceleration test and a wear resistance test were conducted.

[Adhesive strength test]

For each sample of A, B, and C, 5 samples were tested using a Kenken type (Ministry of Construction Building Materials Research Institute method) contact force tester using a 4cIIIX4CI11 steel attachment for materials aged 3 months and 1 year. The average values of those conducted are shown in the table below. However, Table 2 shows the outer lining surface, and Table 3 shows the inner lining surface.

[Corrosion resistance test]

Corrosion tests using sulfuric acid, hydrochloric acid, and seawater were conducted on the various test specimens prepared above in a chemical immersion bath that could be automatically adjusted to constant pi conditions over a period of two years.

Sulfuric acid and hydrochloric acid are kept at a constant pH of 4, and seawater is recycled to maintain the pH.
was 8. The temperature was 20°C in all cases.

(2) Sulfuric acid and hydrochloric acid immersion test Although the A-lining test pieces of the products of the present invention were all colored brown, no change was observed in the surface hardness.

After 6 months, the cement that served as a binder for the test pieces lined with comparative products B and C melted away from the surface, and the layer that appeared to be sand peeled off just by rubbing it with your hands.

Progress of deterioration was observed in the concrete test piece after one week, and the immersion test was discontinued after one month.

■ Seawater immersion test After being immersed in seawater for 2 years, the specimen was cut and its cross section was 0.0%.
Table 4 shows the average value of the depth of white coloring (silver chloride) from the inner and outer peripheries of each sample measured by spraying the IN AgNO3 solution on three samples.

(Space below) [Accelerated carbonation test] Various test specimens were placed in an accelerated neutralization test device (40°C, 90% R,
The carbonation depth from the inner and outer circumferential surfaces was determined by placing the pieces in a chamber (H, Co2 concentration 10%), cutting them after three months, spraying a phenolphthalein solution, and measuring the area of discoloration. The number of samples was three for each, and the average values are shown in Table 5.

(Margin below) Since the CO2 concentration in the atmosphere is 0.03%, the temperature is 40°C.

A three-month test under accelerated conditions of 90% R, H, and Co2 concentration of 10% is several hundred times more severe.

[Abrasion resistance test]

Various test specimens that had been immersed in seawater for 2 years were cut out to a diameter of 100 mm and used as test specimens. The wear resistance of the inner circumferential surface of this specimen was tested using a taper abrasion tester. However, the wear wheel was H22, the load was mtooor, and the cycle was 1000 times, and Table 6 is the average value of three samples.

Table 6 [Effects of the invention] The corrosion-resistant mortar lined pipe according to the present invention can be used for waterworks,
It has adhesive strength and corrosion resistance suitable for sewerage, industrial water supply, or seawater plant piping, and serves as a protection pipe from neutralization reactions and salt damage.

Further, the mortar composition used in the present invention can be applied to both damp and dry concrete surfaces without any problem, and hardens through a hydration reaction similar to that of concrete. Manufacturers can manufacture corrosion-resistant mortar-lined pipes without reducing productivity by simply adding an additional process to the normal manufacturing process for concrete pipes, mortar-lined cast iron pipes, and mortar-lined steel pipes. The process can be simplified and shortened.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a wheel-type centrifugal forming machine used for manufacturing the corrosion-resistant mortar-lined pipe of the present invention.

Claims (1)

[Claims] 1. The inner circumferential surface of a concrete pipe made of concrete, reinforced concrete, or fiber-reinforced concrete, or the inner circumferential surface and outer circumferential surface of these concrete pipes, or cement mortar or fiber-reinforced cement. The inner peripheral surface of a mortar-lined cast iron pipe or mortar-lined steel pipe lined with (a) 20 to 40% by weight of Portland cement (b) 30 to 50% by weight of aggregate (c) 3 to 8% by weight of silica ( A corrosion-resistant mortar lined pipe characterized in that it is lined with a mortar composition consisting of: d) an epoxy resin polymer emulsion (resin solid content) of 10 to 20% by weight; and (e) 10 to 20% of water. 2. A corrosion-resistant mortar-lined pipe, wherein the mortar composition according to claim 1 further contains 1 to 4% by weight of a pigment.