JP2009084118A - Method for producing cement concrete tube by using cement concrete for centrifugal molding, and cement concrete tube produced by the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a cement concrete tube by which can obtain expansibility, can improve chemical deterioration resistance and crack resistance, and increases external pressure strength, and to provide the cement concrete tube produced by the method. <P>SOLUTION: In the method for producing cement concrete tube, a binder composed of an inorganic substance containing alumina cement, SiO<SB>2</SB>and Al<SB>2</SB>O<SB>3</SB>, and an aggregate are blended, and are kneaded at a water/binder ratio of 22 to 60%, so as to prepare cement concrete for centrifugal molding, the cement concrete for centrifugal molding is injected inside a base cement concrete tube subjected to centrifugal molding by using a cement composition containing portland cement, a fine aggregate, a coarse aggregate and a water reducing agent, centrifugal molding is performed, so as to form the internal layer of the base cement concrete tube, and thereafter, hardening is performed at 40 to 80°C by heat curing. In the method for producing a cement concrete tube, the thickness of the internal layer is ≤50% of the total tube thickness. The cement concrete tube is produced by the method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a method for producing a cement concrete pipe using cement for forming centrifugal force mainly used in the field of civil engineering and architecture, and the cement concrete pipe.

  In chemical factories that manufacture and handle chemicals, sewerage facilities that handle various chemicals and pollutants, advanced water treatment plants, etc., centrifugal force molding made of concrete that is highly resistant to chemical degradation There is a need to use concrete pipes.

  In addition, for the repair and reinforcement of centrifugally formed concrete pipes that are placed in a chemically harsh environment, a protective material is installed to cover the deteriorated part, or a protective material is installed on the surface after repair. Yes.

  As a protective material used for such repair and reinforcement, it is necessary to apply a paint or cement with high chemical resistance to protect the surface or to periodically repair.

  An alumina cement that is resistant to chemical deterioration and excellent in corrosion resistance is known (see Patent Document 1).

  Moreover, the manufacturing method of the high intensity | strength mortar hardening body etc. which age the mortar containing an alumina cement and slag at the temperature of 30 degreeC or more are also known (refer patent document 2).

  Alumina cement, however, has rapid initial strength development compared to Portland cement, but has a problem that long-term strength is reduced due to hydrate conversion.

JP 2003-261372 A JP 2006-062946 A

  Even if the chemical deterioration resistance of the cement concrete pipe is high, if cracks occur, salt and sulfate may enter the cement concrete and deteriorate the reinforcing bars. Crack resistance and high external pressure strength (bending strength) are required. It was done.

The present invention blends a binder composed of an alumina cement, an inorganic substance containing SiO ₂ and Al ₂ O ₃ and an aggregate, and kneads them at a water / binder ratio of 22 to 60% for centrifugal force molding. Cement concrete for centrifugal force molding is prepared on the inside of a base cement concrete pipe prepared by preparing a cement concrete and centrifugally molded using a cement composition containing Portland cement, fine aggregate, coarse aggregate, and water reducing agent. Is formed by centrifugal force forming to form an inner layer of a base cement concrete pipe, and then cured by heating curing at 40 to 80 ° C., and SiO ₂ and Al ₂ O ₃ in 100 parts of inorganic material containing, in SiO ₂ is 45 to 98 parts, there is provided a process for the preparation of the cement concrete pipes Al ₂ O ₃ is 0.5 to 45 parts, the inner layer having a thickness of, 3 mm or more, ZenkanAtsu 50% or less of the cement concrete pipe A manufacturing method, a cement concrete pipe which is manufactured by the manufacturing method of the cement concrete pipes.

  By producing a centrifugally formed concrete pipe by the method of the present invention, expandability is obtained, and it becomes possible to improve crack resistance in addition to conventional chemical degradation resistance, and to increase external pressure strength. Is possible.

Unless otherwise specified, parts and% used in the present invention are based on mass.
Moreover, the cement concrete said by this invention is a general term for cement paste, mortar, and concrete.

  The alumina cement used in the present invention is obtained from a clinker pulverized product containing monocalcium aluminate as a main mineral. For example, in a commercial product, trade name “DENKA ALUMINUM CEMENT 1” manufactured by Denki Kagaku Kogyo Co., Ltd. “Denka Alumina Cement No. 2”, “Denka High Alumina Cement”, trade names “SECAR 71” and “SECAR 80” manufactured by Lafarge can be used.

The fineness of the alumina cement is preferably 2,000 to 8,000 cm ² / g in terms of the hydration activity in terms of the specific surface area of the brain (hereinafter referred to as the brain value). If it is less than 2,000 cm ² / g, the reactivity between the inorganic substance containing SiO ₂ and Al ₂ O ₃ may be deteriorated, and if it exceeds 8,000 cm ² / g, curing will be faster and workability will be difficult to ensure. There is a fear.

The inorganic substance containing SiO ₂ and Al ₂ O ₃ (hereinafter referred to as silica-containing substance) used in the present invention is composed mainly of SiO ₂ and Al ₂ O ₃ as chemical components.
Examples of the silica-containing material include FCC which is a catalyst for fluid catalytic cracking, trade name “Hi Clay” of waste activated clay incineration, and coal ash (fly ash).

The content of SiO ₂ and Al ₂ O ₃ component of the silica-containing material is a SiO ₂ is 45 to 98 parts, Al ₂ O ₃ is preferably 0.5 to 45 parts, of SiO ₂ is 50 to 85 parts, Al ₂ O ₃ is more preferably 5 to 35 parts. Outside this range, there is a possibility that a sufficient expansion amount and external pressure strength cannot be obtained.

The fineness of the silica-containing material used in the present invention is preferably from 1,000 to 7,000 cm ² / g, more preferably from 2,000 to 6,000 cm ² / g, in terms of Blaine value. If it is less than 1,000 cm ² / g, the hydration activity is insufficient and the strength and expansion may be insufficient, and if it exceeds 7,000 cm ² / g, the pulverization power is excessively applied, which may be uneconomical.

  In the present invention, the silica-containing material is preferably 5 to 50 parts, more preferably 10 to 40 parts, in 100 parts of the binder composed of alumina cement and silica-containing material. If it is less than 5 parts, a sufficient expansion amount may not be obtained, and an increase in external pressure strength may not be expected. If it exceeds 50 parts, a sufficient expansion amount and compressive strength may not be obtained, and an increase in external pressure strength may not be expected.

The aggregate used in the present invention is not particularly limited, and materials usually used for cement concrete production such as crushed sand, river sand, sea sand, quartz sand, lime sand, crushed stone, river gravel, and limestone should be used. Is possible.
The amount of aggregate used is not particularly limited, but is preferably 50 to 300 parts with respect to 100 parts of the binder. If the amount is less than 50 parts, the amount of the binder may increase, which may be uneconomical. If the amount exceeds 300 parts, fluidity and expandability cannot be obtained, and an increase in external pressure strength may not be expected.

  The amount of water used in the present invention is 22 to 60%, preferably 30 to 50% in terms of water / binder ratio. If it is less than 22%, it may be difficult to ensure the predetermined fluidity. If it exceeds 60%, a sufficient expansion amount and strength cannot be obtained, and an increase in external pressure strength may not be expected.

  In the present invention, in addition to alumina cement, silica-containing material, and aggregate material, water reducing agent, high performance water reducing agent, AE water reducing agent, fluidizing agent, setting modifier, vinylon fiber, acrylic fiber, and carbon One or two or more kinds of fibrous substances such as fibers can be used as long as the object of the present invention is not impaired.

  The mixing method of each material in this invention is not specifically limited, It may mix when each material is mixed, and it does not interfere even if the one part or all part is mixed beforehand.

  Any existing apparatus can be used as the mixing apparatus, and examples thereof include a tilting cylinder mixer, a Henschel mixer, a V-type mixer, and a Nauter mixer.

  The kneading method in the present invention is not particularly limited. For example, the material mixed in 10 to 20 minutes is used for 60 to 180 seconds from the addition of water using a tilting barrel mixer, a biaxial forced mixer, an omni mixer, and the like. It is usual to knead to the extent.

  In the present invention, the centrifugal force-forming cement concrete of the present invention is introduced into the inner surface of a centrifugally formed base cement concrete pipe, and is centrifugally molded. Then, the centrifugal force-forming cement of the present invention is applied to the inner surface of the base cement concrete pipe. An inner layer of concrete is formed, but it is also possible to form a cement concrete pipe by centrifugal molding only with the cement for forming centrifugal force.

The manufacturing method of the base cement concrete pipe can be a normal method and is not particularly limited.
For example, Portland cement, fine aggregate, coarse aggregate, and water reducing agent can be kneaded with water to prepare cement concrete, and then base cement concrete pipe can be formed by centrifugally forming it. is there.
Portland cement, fine aggregate, coarse aggregate, and water reducing agent are not particularly limited, and those that are usually used can be used.
Centrifugal force molding conditions are not particularly limited. For example, cement concrete is charged at low speed G2.5, low speed G2.5-5 for 5-10 minutes, medium speed G10-20, 2-8 minutes, And it is possible to form a base cement concrete pipe by centrifugal molding at a high speed G30-40 under three-stage centrifugal force molding conditions for 5-15 minutes.

In this invention, the cement concrete for centrifugal force shaping | molding of this invention is thrown into the inner surface of the shape | molded base cement concrete pipe, and the inner layer of a base cement concrete pipe is formed.
In the present invention, the method of forming the inner layer of the base cement concrete pipe is not particularly limited. For example, the centrifugal concrete of the present invention is formed on the inner surface of the molded base cement concrete pipe at a low speed G2. 5 at three low speed G2.5-5, 1-5 minutes, medium speed G10-20 1-3 minutes, high speed G30-40 5-15 minutes. It is normal.

  The inner layer thickness formed from the cement concrete for centrifugal forming is preferably 3 mm or more and 50% or less of the tube thickness, more preferably 5 mm or more and 30% or less of the tube thickness. If it is less than 3 mm, the external pressure strength may not increase, and even if it exceeds 50% of the tube thickness, an increase in external pressure strength cannot be expected.

In the present invention, for example, by performing heat curing after forming the centrifugal force, expandability can be obtained and the external pressure strength can be increased.
The method of heating curing is not particularly limited, and both steam curing and autoclave curing are possible.
The curing temperature is preferably 40-80 ° C, more preferably 50-65 ° C. If the curing temperature is outside the above range, the amount of expansion may be small, and an increase in external pressure strength cannot be expected.

  In the present invention, the pre-treatment time from centrifugal force molding to warm curing is particularly important, preferably within 8 hours, and more preferably from 2 to 4 hours. If the preposition time is outside this range, the amount of expansion is small, and the external pressure strength may be small. However, this does not apply when curing is delayed using a setting modifier or the like.

  The heating rate of heat curing is also particularly important, preferably 10 ° C./hr or more, and more preferably 20 ° C./hr. If the rate of temperature rise is slow, the amount of expansion becomes small and the external pressure strength may be reduced, and if the rate of temperature rise is too fast, cracks may occur.

  The holding time of the curing temperature is not particularly limited, but is usually preferably about 3 to 6 hours. If it is less than 3 hours, the amount of expansion will be small and the external pressure strength may be small. Even if it is cured beyond 6 hours, no further increase in external pressure strength can be expected.

  Hereinafter, the present invention will be further described based on experimental examples of the present invention, but the present invention is not limited thereto.

Experimental example 1
Cement 450 kg / m ^3, water 170 kg / m ^3, fine aggregates 612kg / m ^3, with coarse aggregate 1,145kg / m ^3, and water reducing agent 2.7 kg / m ^3, slump 8cm, s / a35%, and W / C37.8% concrete mix was used and mixed for 3 minutes with a 50 liter planetary forced kneading mixer to prepare 30 liters of concrete.
The prepared concrete is put into a mold for forming a centrifugal force having a diameter of 20 cm, a length of 30 cm and a thickness of 4 cm. The centrifugal force is low speed G2.5 for 5 minutes, medium speed G10 for 2 minutes, and high speed G30 for 5 minutes. The outer layer of the centrifugal force molded specimen was formed under three-stage centrifugal force molding conditions.
Next, using a binder consisting of 80 parts of alumina cement and 20 parts of silica-containing material, and mixing the water / binder ratio and binder / sand ratio shown in Table 1, knead in a mortar mixer for 2 minutes, and then form a centrifugal force. A mortar for the inner layer of the test specimen was prepared.
In a 20 ° C environment, insert the inner layer mortar prepared with a low-speed G2.5 centrifugal force so that the inner layer thickness is 5 mm. Centrifugal force molding conditions for 1 minute at low-speed G2.5 and 10 minutes at high-speed G30 The inner layer was formed. Thereafter, the preheating time was 4 hours, the temperature was raised at a rate of 15 ° C./hr, the temperature was kept at 65 ° C. for 5 hours, and then a natural temperature drop steam curing was performed to form a centrifugal force molded specimen. After demolding at a material age of 1 day, water curing was performed and an external pressure test was conducted at a material age of 7 days. The results are also shown in Table 1.
When the water / binder ratio was small and mixing was difficult, a water reducing agent was added to such an extent that mold filling was possible.
For comparison, 100 parts of cement, 200 parts of sand, and 50 parts of water were mixed to prepare a plain mortar for the inner layer, and a centrifugally formed concrete tube was similarly formed.
Measure the external pressure strength of the molded centrifugal force molded concrete pipe and the inner layer formed with plain mortar and measure the external pressure strength of the molded concrete tube (centrifugal force molded specimen external pressure strength / plain mortar to form the inner layer) The external pressure strength ratio was calculated from the external pressure strength of the centrifugally formed concrete pipe. The results are also shown in Table 1.

<Materials used>
Alumina cement: AC, trade name “Denka Alumina Cement No. 1” manufactured by Denki Kagaku Kogyo Co., Ltd., density 3.00g / cm ³ , brain value 5,000cm ² / g
Silica-containing material A: FCC of fluid catalytic cracking catalyst, commercially available, SiO ₂ 65.7%, Al ₂ O ₃ 27.5%, density 2.70 g / cm ³
Fine aggregate: Natural sand from Himekawa water system, Niigata prefecture, density 2.62g / cm ³
Coarse aggregate: Crushed stone from Himekawa water system, Niigata prefecture, aggregate size 5-13mm, density 2.64g / cm ³
Water: Tap water reducing agent: Polycarboxylic acid-based high-performance water reducing agent, commercial cement: Ordinary Portland cement, sand made by Denki Kagaku Kogyo Co., Ltd .: Standard sand

<Measurement method>
External pressure strength: Bending strength, measured according to JIS A 5372 “Precast reinforced concrete products” Annex 3. Centrifugal molded specimens with a diameter of 20 x length of 30 cm x thickness of 4.5 cm, or formed by forming an inner layer with plain mortar, a brand name made by Marui Manufacturing Co., Ltd. Using HI-TRITRON (3000KN) compression tester, load and measure from above and below

Experimental example 2
The experiment was performed in the same manner as in Experimental Example 1 except that the inner layer mortar formed using the binder shown in Table 2 and the mixture of water / binder ratio 50% and binder / sand ratio 1/2 was used. The results are also shown in Table 2.

<Materials used>
Silica-containing material B: Waste activated clay incineration, Toei Chemical Co., Ltd. trade name “Hi-Clay”, commercial product, SiO ₂ 79.8%, Al ₂ O ₃ 9.25%, density 1.97 g / cm ³
Silica substance C: fly ash, cement admixture, commercial product, SiO ₂ 60.0%, Al ₂ O ₃ 27.0%, density 2.05g / cm ³

Experimental example 3
Table 3 shows the inner layer mortar prepared by using 80 parts of alumina cement, 20 parts of silica-containing material, 20 parts of water, binder ratio of 50% water / binder ratio, and 1/2 binder / sand ratio. The same operation as in Experimental Example 1 was performed except that the thickness of the inner layer mortar was adjusted.
The total thickness of the centrifugally formed concrete pipe formed by forming the inner layer with the formed centrifugal force test specimen and plain mortar was constant at 4.5 cm. The results are also shown in Table 3.

Experimental Example 4
Table 4 shows the inner layer mortar prepared using 80 parts of alumina cement, 20 parts of silica-containing material, 20 parts of water, 50% water / binder ratio, and 1/2 binder / sand ratio. The experiment was performed in the same manner as in Experimental Example 1 except that steam curing was performed at a preliminary time, a heating rate of 15 ° C / hr, a curing temperature of 65 ° C, and a holding time of 5 hours. The results are also shown in Table 4.

Experimental Example 5
Using a mortar for an inner layer prepared using a binder comprising 80 parts of alumina cement, 20 parts of silica-containing material, 20% water / binder ratio, and a binder / sand ratio of 1/2, The experiment was performed in the same manner as in Experimental Example 1 except that the steam curing was performed at the time, the heating rate shown in Table 5, the curing temperature 65 ° C., and the holding time 5 hours. The results are also shown in Table 5.

Experimental Example 6
Using a mortar for an inner layer prepared using a binder comprising 80 parts of alumina cement, 20 parts of silica-containing material, 20% water / binder ratio, and a binder / sand ratio of 1/2, The test was performed in the same manner as in Experimental Example 1 except that steam curing was performed at the time, the heating rate of 15 ° C./hr, the curing temperature of 65 ° C., and the holding time shown in Table 6. The results are also shown in Table 6.

Claims (4)

A cement concrete for centrifugal force molding is prepared by blending a binder composed of alumina cement, an inorganic substance containing SiO ₂ and Al ₂ O ₃ and an aggregate, and kneading at a water / binder ratio of 22-60%. Then, the cement concrete for centrifugal force molding is put inside the base cement concrete pipe formed by centrifugal force molding using a cement composition containing Portland cement, fine aggregate, coarse aggregate, and water reducing agent, A method for producing a cement concrete pipe, which is formed by centrifugal force forming to form an inner layer of a base cement concrete pipe and then cured by heat curing at 40 to 80 ° C. 100 parts of an inorganic substance containing SiO ₂ and Al ₂ O _3, of SiO ₂ is 45 to 98 parts, the production method of cement concrete pipe according to claim 1 Al ₂ O ₃ is 0.5 to 45 parts.   The method for producing a cement concrete pipe according to claim 1 or 2, wherein the thickness of the inner layer is 3 mm or more and 50% or less of the total pipe thickness.   The cement concrete pipe manufactured with the manufacturing method of the cement concrete pipe as described in any one of Claims 1-3.