JPS642834B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a cement-based injection material composition and a buried pipe repair method using the same, and in particular, it can be easily repaired while buried as a countermeasure against aging of existing (buried) metal pipes such as water pipes. The purpose is to provide construction methods that can be used. Pipe is a type of pipe cleaning method used as a repair method for buried pipes such as cast iron or steel water distribution pipes, water conveyance pipes, power generation penstock pipes, gas pipes, etc. when they have deteriorated or cracked. Reverse construction method is known. This method involves inserting a polyethylene pipe with a small diameter inside the buried pipe to form a certain gap between the inner surface of the buried pipe (main pipe) and the outer surface of the polyethylene pipe, and then injecting (press-fitting) a cement-based injection material into this space. ) and harden it to strengthen and repair the three-layer structure consisting of the main pipe, cement layer, and polyethylene pipe. The cement-based injection materials used in the above-mentioned pipe reverse construction method have excellent fluidity and are easy to injection (press-fit), have little separation of materials such as breathing phenomena, and have high material strength after hardening. It is required to have excellent adhesive strength with the inner surface of the buried pipe and to not cause shrinkage cracks after curing. Currently, for these purposes, attempts are being made to use cementitious injection material compositions in which bentonite is added to cement milk consisting of cement and water. However, although the addition of bentonite has some effect on improving the fluidity of the injection material due to its suspension performance and thixotropic properties, if the injection material composition is left standing, there will be a lot of floating water and the material will separate. Further, there is a decrease in the strength of the material after injection, resulting in problems such as a decrease in adhesive strength with the buried pipe. The inventors of the present invention have conducted extensive research in consideration of these technical issues, and have found that cement milk (or cement paste) consisting of cement and water is combined with water-soluble cellulose alone or with water-soluble cellulose ether, a cement dispersant, and an antifoaming agent. The present invention was completed after confirming that an excellent cementitious injection material composition can be obtained by adding a chemical agent, and that repair work for buried pipes can be easily carried out by using this injection material composition. According to the present invention, by using the above-mentioned additive components, protective colloid properties and dispersibility are imparted, and even if the cement-based injection material composition is left standing after preparation, floating water does not occur, and cement Components do not settle, and separation of materials is drastically reduced. The fluidity of the material is excellent, making press-fitting (injection) work easy, and since there is no separation of the material, problems such as material clogging during the press-fitting process are eliminated. Due to its viscosity and thixotropy,
The adhesiveness between the material after injection and the inner surface of the existing pipe (buried pipe) is strengthened, and the adhesive strength after curing is greatly improved, and the three-layer structure of the main pipe, cement layer, and polyethylene pipe is firmly integrated. . Furthermore, due to the water reduction and dispersion effect, it exhibits good fluidity even under low water/cement ratio conditions, resulting in increased material strength and no cracking after curing. This brings about some very remarkable effects. The present invention will be explained in detail below. (a) The water-soluble cellulose ether used in the present invention is typified by alkyl cellulose, hydroxyalkyl cellulose, and hydroxyalkyl alkyl cellulose, and the desirable substituents (number of carbon atoms) and degree of substitution of these cellulose ethers are The alkyl group has 1 to 2 carbon atoms and the degree of substitution (DS) per anhydroglucose unit is 1.0.
~2.5 (preferably 1.3 to 2.0) alkyl cellulose, the hydroxyalkyl group has 2 to 2 carbon atoms
Hydroxyalkylcellulose having 4 carbon atoms and a molar degree of substitution (MS) per anhydroglucose unit of 1.0 to 3.5 (preferably 1.5 to 2.5), hydroxyalkyl cellulose having 2 to 4 carbon atoms and molar substitution per anhydroglucose unit. It is a hydroxyalkyl alkylcellulose having an alkyl group having 1 to 2 carbon atoms and a degree of substitution (DS) per anhydroglucose unit of 0.5 to 2.5, and a viscosity of 0.05 to 2.0. It is preferable that the value at 20° C. in a 2% aqueous solution is 15 to 100,000 CPS. Such cellulose ethers include methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, hydroxybutylmethylcellulose,
Examples include hydroxyethylethylcellulose and hydroxybutylethylcellulose. Among the cellulose ethers mentioned above, hydroxyalkyl alkyl cellulose exhibits high protective colloidal properties and water retention properties, and is effective in preventing separation of materials such as the breathing phenomenon. Hydroxypropyl methyl cellulose is particularly excellent in this respect. be. In the present invention, in addition to the above (a) water-soluble cellulose ether, (b) a cement dispersant and (c) an antifoaming agent are used if necessary. This (b) cement dispersant includes those whose main component is lignin sulfonate, those whose main component is polyoxyethylene alkylaryl ether, those whose main component is polyol composite, and those whose main component is aromatic polycyclic condensate. Examples include those whose main component is a sulfonate of water-soluble melamine-formalin resin (methylolmelamine), and those whose main component is a sulfonate of water-soluble melamine-formalin resin (methylolmelamine). Among these, lignin sulfonate-based dispersants are particularly superior in that they exhibit a dispersing effect without impairing the fluidity of the material when used in combination with the above-mentioned water-soluble cellulose ether, and also provide a water-reducing effect. There is. The proportion of component (B) used is 0 to 300 parts by weight, preferably 50 parts by weight, per 100 parts by weight of component (B).
~250 parts by weight. (c) Antifoaming agents include polyoxyethylene-polyoxypropylene block copolymers that are resistant to alkalinity, nonionic special compounds, higher alcohols,
Examples include tributyl phosphate and silicone. Particularly desirable are those whose main component is a polyoxyethylene-polyoxypropylene block copolymer. The use of these antifoaming agents suppresses air entrainment into the cement injection material, increases material strength after curing, and improves adhesive strength. Antifoaming agents based on oxypropylene block copolymers are preferred. The usage ratio of (c) component is (b) component
The amount is 0 to 100 parts by weight, preferably 20 to 50 parts by weight, per 100 parts by weight. The amount of the additives mentioned above is the amount used when component (a) is used alone, or the total amount of component (a) and these when components (b) and (c) are used together.
0.01 to 10 parts by weight (preferably 0.05 to 3 parts by weight)
(parts by weight). 0.01
If it is less than 10 parts by weight, the effect will be small, and if it is added in excess of 10 parts by weight, the viscosity of the cement-based injection material will increase significantly, and the adhesive force with the pipe wall will become stronger, resulting in a large pressure being applied during injection. Therefore, the problem arises that construction becomes difficult. The additives may be added by dry blending them into cement or by dissolving them in additive water beforehand. It should be noted that there is no problem in adding inorganic additives such as bentonite along with the above additives, and in construction where there is a large gap between the existing pipe and the polyethylene pipe inserted therein, fine-grained aggregate such as silica sand may be used. It may also be a pouring material composition made into mortar by adding agarite, slag, alumina-silica microspheres, etc. Next, a method of repairing a buried pipe using the cement-based injection material composition of the present invention will be explained. First, water will be cut off in the construction section, and bent pipes, T-shaped pipes, etc. will be excavated and cut. After this, clean and remove rust etc. from the inner surface of the buried pipe. Insert a plastic pipe such as a polyethylene pipe into the cleaned buried pipe. One span is approximately 100m as standard, and after excavating and cutting the pipe, connect the wire rope to the winch on the opposite side, and pull it in from the cut pipe opening. Existing pipes that have been cut and removed will be replaced with new pipes and connected and restored. For the connecting part, use a special short pipe and a short brim pipe between the short pipes to connect to the existing installation. Prior to injection, the inserted polyethylene pipe is filled with water and the internal pressure is adjusted to approximately 2 kg/cm ² . The through hole of the special short pipe is connected to a grouting pump directly connected to a grout mixer, and cement milk, which is a cement-based injection material composition according to the present invention, is injected into the gap between the buried pipe and the polyethylene pipe. When the injection material composition according to the present invention is used for injection, there is no material separation of cement milk after water injection, and the gap between the buried pipe and the polyethylene pipe can be completely filled with one injection. This means that when the same cement milk is injected again after a certain period of time (30 minutes to 2 hours) has passed after the first injection, the specific gravity of the cement milk flowing out from the discharge port will be lower than that of the cement milk injected from the injection port. It was confirmed that there was no phenomenon of material separation such as floating water in the first injection material. As a result, the workability was significantly improved and the construction time was shortened. On the other hand, when conventional cement-based injection with bentonite added is used, floating water occurs inside the pipe after a certain period of time (30 minutes to 60 minutes) after injection.
It is necessary to repeat the process of injecting cement milk for the second and third time (minutes), and then draining the floating water inside the pipe from the discharge port. As a result, the problem arises that the construction time for each section is significantly extended. Next, a specific example will be given. However, the additives used in each example are as follows. 〇Bentonite...250 mesh pass product (manufactured by Nippon Bentonite Co., Ltd.) 〇Water-soluble cellulose ether...Metrose
90SH-30000 (manufactured by Shin-Etsu Chemical Co., Ltd.) Cement dispersant... Pozolith 5L (manufactured by Nisso Master Builders Co., Ltd.) Antifoaming agent...SN-14HP (manufactured by San Nobuco Co., Ltd.) Example 1 Cement In order to investigate the separation status of system injection materials,
Immediately put the kneaded ingredients into a 500ml graduated cylinder and let it stand to measure the breathing water volume (floating water volume).
was measured. In addition, a flow test was conducted to examine the fluidity of this material. However, the flow cone is 42.5mmφ
A ring of ×30 mmH was used, and the spreading width of the material was measured without vibration. To prepare the materials, cement and additives were mixed in advance, put into a mixer, water was added, and kneaded for 2 minutes. A mortar mixer specified in JIS R5201 was used as the mixer. The results are shown in Table 1.

[Table] *Amount of additive used is weight% of cement
Example 2 The effect of using the cellulose ether additive according to the present invention and bentonite together as an additive composition for cement-based injection materials, and the addition method of adding the additives: mixing powder with cement and adding it dissolved in water. We investigated the differences between cases. The breathing test and flow test were conducted in the same manner as in Example 1. The results are shown in Table 2.

[Table] * Additives and bentonite usage amounts are weight percent based on cement.
Example 3 The strength of cement-based injection material was measured under the following conditions. Measuring device: Amsler type compression testing machine Specimen dimensions: 4 x 4 x 16 cm Curing and material age of the sample: 20°C, 85% RH air curing material age: 28 days Material adjustment was performed using the same method as in Example 1. did. The results are shown in Table 3.

[Table] Additive: Bentonite Example 4 A construction experiment was conducted under the following conditions using a pouring material to which the additive according to the present invention and bentonite were added. 〇Injection distance 80m 〇Buried pipe inner diameter; 450m/mφ 〇Polyethylene pipe diameter; 420m/mφ 〇Water pressure; 1.8Kg/cm ² 〇Group material composition

【table】

[Table] To knead the materials, cement and additives were mixed in advance, and then water was added and kneaded using a ground mixer. A second injection was made one hour after the first injection, and a third injection was made two hours later.The specific gravity and amount of water poured out of the cement milk flowing out from the discharge port were measured. Checked the filling status. The results are shown in Table 4.

【table】

Claims (1)

[Claims] 1. For 100 parts by weight of cement, (a) 100 parts by weight of water-soluble cellulose ether, (b) 0 parts by weight of cement dispersant.
300 parts by weight and (iii) a cementitious injection material composition comprising 0.01 to 10 parts by weight of an additive consisting of 0 to 100 parts by weight of an antifoaming agent and 50 to 100 parts by weight of water. 2. Insert a plastic pipe into the buried pipe to form a void between the inner surface of the buried pipe and the outer surface of the plastic pipe, and add (a) 100 parts by weight of water-soluble cellulose ether to 100 parts by weight of cement in this void. parts by weight, (b) cement dispersant 0 to 300 parts by weight, and (c)
0.01 to 10 additives consisting of 0 to 100 parts by weight of antifoaming agent
A buried pipe repair method characterized by injecting and curing a cement-based injection material made by adding 50 to 100 parts by weight of water and 50 to 100 parts by weight.