JP2007176740A - Thickening mortar - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide thickening mortar having excellent thickening applicability by a plastering process, in which reduction in strength after the application that has been easily generated by increasing the thickening applicability is hardly caused, the generation of cracks can be suppressed as well, and, even in the case a lightweight aggregate is largely used for lightening, a difference in strength with mortar only using a common aggregate can be remarkably reduced. <P>SOLUTION: The thickening mortar comprises: fine aggregate composed of lightweight aggregate and common aggregate or fine aggregate composed of lightweight aggregate; portland cement; an alkaline-earth metal sulfate; an expanding agent; a thickener; and a dispersant. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cement-based thickening mortar mainly used for repairing mortar and concrete structures.

Repair of mortar and concrete structures using cement-based mortar is mainly carried out by either spraying the mortar (spraying method) or applying (left plastering method) to the repaired part. In general, spraying methods are often used for thin construction layers and large construction areas. For example, repairing the back of reinforced concrete structures and building ceilings The plastering method is often adopted for objects that are difficult to perform and repair sites that require a thicker construction layer. Since the mortar used for the spraying method is mainly due to the instantaneous setting of the mortar due to the fixation of the mortar to the construction target structure, a mortar containing a quick setting component or a setting promoting component is used. (For example, see Patent Document 1.) On the other hand, the mortar used in the plastering method cannot ensure the pot life and the construction is extremely difficult. A thickener, a polymer resin, or the like is blended in order to improve adhesion to the body. (For example, refer to Patent Document 2.) When the construction mortar layer is thickened by the plastering method, the drying shrinkage after curing is increased and the possibility that cracks are likely to occur increases. Further, the thick mortar layer is likely to peel off or sag from the construction target structure. In order to prevent such cracks and to fix the structure to the structure, it is possible to increase the polymer resin component in the mortar. However, the increase in the polymer resin component is liable to increase the viscosity so that the plastering workability is hindered or the strength is easily lowered even when the work is performed. In particular, in the thick mortar used for repairing the ceiling portion of a structure, in order to prevent peeling due to its own weight, a lightweight aggregate is often used for the aggregate (see, for example, Patent Document 3). It is more likely to drop.
Japanese Patent Laid-Open No. 11-322397 JP-A-2005-15306 Japanese Patent Laid-Open No. 2003-119063

  The present invention is a mortar excellent in plastering workability by plastering method, it is difficult to reduce strength after construction, cracking can be suppressed, and even when a large amount of lightweight aggregate is used for weight reduction It is an object of the present invention to provide a thickened mortar that can suppress a decrease in strength and can significantly reduce a difference in strength from a mortar using only ordinary aggregate as an aggregate.

  As a result of intensive investigations for solving the problems, the present inventors have used at least a lightweight aggregate as a fine aggregate, and a mortar in which alkaline earth sulfate, an expansion material, a thickener and a dispersant are added to Portland cement. However, it has good thickness workability regardless of the construction location, does not generate large shrinkage that leads to cracks, and has high bond phase strength, so even if a large amount of lightweight aggregate is used for the aggregate, it is strong The knowledge that a mortar with a small decrease in expression was obtained was obtained, and the present invention was completed.

  That is, the present invention is a thickening mortar represented by the following (1) to (2). (1) Thickness comprising a fine aggregate made of lightweight aggregate and normal aggregate or a fine aggregate made of lightweight aggregate, Portland cement, alkaline earth metal sulfate, expansion material, thickener and dispersant. Attached mortar. (2) The thickening mortar according to (1), further comprising one or more of polymer dispersion, re-emulsifying powder resin, and fiber.

  ADVANTAGE OF THE INVENTION According to this invention, the mortar for thickening which is excellent in thickening property and plastering finish property, and has high intensity | strength expression property is obtained. In addition, even when using lightweight aggregates for weight reduction, it is possible to obtain the same strength as mortar using ordinary aggregates, so even if it is difficult to construct due to its own weight, it should be used as a thickening repair material etc. Can do.

  The thickening mortar of the present invention comprises a fine aggregate made of lightweight aggregate and normal aggregate, or a fine aggregate made of lightweight aggregate, Portland cement, alkaline earth metal sulfate, expansion material, thickener and dispersant. It is a mortar composition containing. The Portland cement used in the thickening mortar of the present invention is a main component for forming a mortar binder phase. For example, any Portland cement such as normal, early strength, very early strength or moderate heat can be used. From the viewpoint of cost and handleability, ordinary Portland cement is preferable. However, in order to perform repair work in a short period of time, it is more preferable to use early strength or super early strength Portland cement, or a combination of ordinary Portland cement and ordinary Portland cement.

  Examples of the alkaline earth metal sulfate used in the thickening mortar of the present invention include magnesium sulfate, calcium sulfate, and barium sulfate, and one or more of these can be used. Thickening workability is improved by blending alkaline earth metal sulfate. 1-9 mass parts is preferable with respect to 100 mass parts of Portland cement, and, as for the compounding quantity of alkaline-earth metal sulfate, 2-8 mass parts is more preferable. If the blending amount of the alkaline earth metal sulfate is less than 1 part by mass, the blending effect cannot be obtained, so that it is not suitable. If it exceeds 9 parts by mass, the setting may proceed too quickly, making it difficult to knead the blend. So it is not appropriate.

  The expansion material used in the thickening mortar of the present invention is not particularly limited as long as it can be used for mortar and concrete. For example, calcium lime as an active ingredient as a hydration-expandable expansion agent or calcium The thing which uses sulfa aluminate as an active ingredient can be mentioned. By blending and using the expansion material, drying shrinkage is mainly suppressed, the shape and dimension stability of the construction part can be achieved, and the occurrence of shrinkage cracks can be prevented. 2-15 mass parts is preferable with respect to 100 mass parts of Portland cement, and, as for the usage-amount of an expandable material, 3-13 mass parts is more preferable. If the amount of the expanded material used is less than 2 parts by mass, the shrinkage cannot be sufficiently suppressed and cracks tend to appear, which is not appropriate. On the other hand, if it exceeds 15 parts by mass, there is a risk of overexpansion, which is not appropriate.

  Further, the thickener used in the thickening mortar of the present invention may be any as long as it can be used in mortar or concrete, and examples thereof include water-soluble cellulose derivatives and polyvinyl alcohols. Examples of the water-soluble cellulose derivative include cellulose derivatives such as methyl cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl cellulose, and cellulose sulfate. By blending a thickener, the adhesion of the mortar to the structure during plastering can be strengthened, and the occurrence of dry cracks after the repair, and peeling / peeling can be prevented. The amount of the thickener used is preferably 0.2 to 1.0 parts by weight with respect to 100 parts by weight of Portland cement, and less than 0.2 parts by weight is not suitable because only mortar with poor adhesion can be obtained. If it exceeds 1.0 part by mass, the viscosity becomes too high and the mixing resistance at the time of blending is increased, which may impair workability.

  Further, the dispersant used in the thickening mortar of the present invention may be any one that can be used in mortar or concrete, and includes a fluidizing agent, a water reducing agent, a high performance water reducing agent, an AE water reducing agent, and a high performance AE water reducing agent. What is called can be used. Specifically, water reducing agents such as naphthalene sulfonic acid, melamine, lignin, and polycarboxylic acid can be exemplified. Of these, naphthalene sulfonic acid-based dispersants are preferred because their water-reducing effect is hardly reduced even when used in combination with thickeners. By blending a dispersant, the unit water amount can be lowered and the strength can be improved without hindering workability, and even when a thickener is blended, a homogeneous blend is easily obtained. The amount of the dispersant used is preferably 0.5 to 1.5 parts by mass, more preferably 0.6 to 1.3 parts by mass with respect to 100 parts by mass of Portland cement. If the amount is less than 0.5 parts by mass, the blending effect does not appear sufficiently, so that it is not appropriate. If the amount exceeds 1.5 parts by mass, the effect may be delayed.

  In addition, the thickening mortar of the present invention uses only a lightweight fine aggregate as a fine aggregate, or uses a lightweight aggregate and a normal aggregate in combination. For example, since it is necessary to reduce the weight of the mortar to be used depending on the construction site such as the ceiling, at least a lightweight aggregate is used to reduce the weight of the mortar. When a light aggregate and a normal aggregate are used in combination, the reduction effect becomes higher as the use ratio of the light aggregate increases, and the lightest aggregate is the highest when only the light aggregate is used. In the present invention, the use ratio of both the lightweight aggregate and the ordinary aggregate is not particularly limited, but the proportion of the lightweight aggregate in the fine aggregate is surely performed regardless of the construction location. Is preferably 70% by volume or more. The ordinary aggregate may be any material that can be used for mortar and concrete, and examples thereof include river sand, sea sand, mountain sand, and crushed sand. The lightweight aggregate can be any of organic lightweight aggregates, such as EVA calcium carbonate foam aggregate and styrene foam aggregate, and lightweight aggregates of natural or artificial inorganic materials. It is preferable to use an inorganic lightweight aggregate because it is easy to ensure the property. Lightweight aggregates of inorganic materials are not particularly limited as long as they have an absolute dry specific gravity of 1.8 or less. For example, natural lightweight aggregates crushed and sized volcanic gravel, natural ore such as expansive shale and rhyolite are necessary. Artificial lightweight aggregates fired with foaming aid, industrial by-products and waste such as expanded slag, coal ash, sewage sludge incineration ash, municipal waste incineration ash, etc. Lightweight aggregate etc. are mentioned. The fine aggregate used in the present invention is preferably 3 to 10 parts by mass, more preferably 4 to 9 parts by mass with respect to 100 parts by mass of Portland cement, regardless of whether it is a lightweight aggregate or a normal aggregate. If it is less than 3 parts by mass, it is difficult to improve the water-tightness after construction, and if it exceeds 10 parts by mass, the strength development may be deteriorated.

  Moreover, it is preferable that the thickening mortar of this invention is a thing in which any 1 type (s) or 2 or more types of polymer dispersion, re-emulsification type powder resin, and a fiber were mix | blended in addition to the said component.

  The polymer dispersion and re-emulsifying powder resin that can be used in the thickening mortar of the present invention may be any one that can be used in cement, mortar, or concrete. For example, the polymer dispersion or re-emulsification type specified in JIS A6203 Powder resin can be used. More specifically, examples of the polymer dispersion include resins such as polyacrylic acid ester, styrene butadiene, and ethylene vinyl acetate, and examples of the re-emulsifying powder resin include vinyl acetate / vinyl versatate, vinyl acetate / versaic acid. Examples include vinyl / acrylic acid esters. By blending the polymer dispersion or the re-emulsifying powder resin, the adhesion to the concrete structure is further increased, and the water shielding property is greatly improved. The amount of the polymer dispersion or re-emulsifying powder resin used is preferably 0.02 to 0.7 parts by mass in terms of solid content, based on 100 parts by mass of Portland cement, when these are used in combination. . If it is less than 0.02 parts by mass, it is not suitable because almost no compounding effect can be obtained, and if it exceeds 0.7 parts by mass, it is not suitable because it tends to increase viscosity and increase kneading resistance, and the plastering workability tends to decrease. .

  The fiber that can be used in the thickening mortar of the present invention may be any water-insoluble one that can be used in mortar or concrete, such as acrylic fiber, vinylon fiber, aramid fiber, polypropylene fiber, polyethylene fiber, etc. Examples thereof include polymer fiber, carbon fiber, alkali-resistant fiber glass, and stainless steel fiber. By blending and using fibers, thickening enhancement and cracking suppression can be imparted without increasing the blending amount of the thickening component, polymer dispersion or re-emulsifying powder resin. The blending amount of the fiber is preferably 0.1 to 0.5 parts by mass with respect to 100 parts by mass of Portland cement. If it is less than 0.1 parts by mass, the blending effect will be poor, so it is not suitable. If it exceeds 0.5 parts by mass, the mixing and workability will decrease unless the water cement ratio is increased, and the strength will decrease if the water cement ratio is increased. Is not appropriate.

  Further, the thickening mortar of the present invention may be one in which components other than those described above are blended within a range not losing the effects of the present invention. Examples of such components include latent hydraulic materials such as blast furnace slag and sewage sludge molten slag, pozzolanic reactive materials such as coal ash and silica fume, air entraining agents, antifoaming agents, shrinkage reducing materials, rust preventives, white flower Examples thereof include an inhibitor, a water repellent, and a pigment.

  The manufacturing method of the thickening mortar of the present invention is not particularly limited, and can be prepared by a method similar to a general cement-based mortar material. For example, the compounding materials are collectively charged into a commercially available mortar mixer, Add water and mix. The blending amount of water is preferably 14 to 18 parts by mass with respect to 100 parts by mass of the total powder component in the mortar. If it is less than 14 parts by mass, the kneading resistance at the time of blending is increased, so that it is not appropriate. If it exceeds 18 parts by mass, the strength development is reduced, and thickening tends to be difficult. Further, the thickening mortar according to the present invention can be plastered by a method similar to that used in a conventional cement-based mortar repair material.

Hereinafter, the present invention will be described in detail by way of examples.
[Production of Restoring Material] The materials and water selected from A1 to A2, B1 to B4, C1 to C3, D, E, F1 to F4, G1 to 2, and H1 to 3 shown below are shown in Table 1. It put into the mortar mixer so that it might become a compounding quantity, and it mixed for 3 minutes under the temperature of about 20 degreeC, and produced the mortar (this invention products 1-8, reference products 11-17).

A1: Normal Portland cement (manufactured by Taiheiyo Cement Co., Ltd.)
A2: Early strong Portland cement (manufactured by Taiheiyo Cement Co., Ltd.)
B1; Type II anhydrous gypsum (manufactured by Central Glass Co., Ltd.)
B2: Magnesium sulfate (commercially available reagent)
B3: Aluminum sulfate (commercially available reagent)
B4: Sodium aluminate (commercially available reagent)
C1: Quicklime expansion agent (trade name “Pacific Expan”, manufactured by Taiheiyo Materials Co., Ltd.)
C2: Calcium sulfa aluminate-based swelling agent (trade name “DENKA CSA”, manufactured by Denki Kagaku Kogyo Co., Ltd.)
C3: Calcium sulfa aluminate-based swelling agent (trade name “Pacific Gypcal” manufactured by Taiheiyo Materials Co., Ltd.)
D: Hydroxypropyl methylcellulose (trade name “90SH-4000”, manufactured by Shin-Etsu Chemical Co., Ltd.)
E: Naphthalene sulfonic acid-based high-performance water reducing agent (trade name “Mighty 100”, manufactured by Kao Corporation)
F1: ordinary fine aggregate (mountain sand, particle size 0.15 to 0.6 mm, FM = 1.52)
F2: Organic material-based lightweight fine aggregate (foamed styrene beads, bulk specific gravity 0.05, particle size 1-2 mm)
F3: inorganic material-based lightweight fine aggregate (EVA-calcium carbonate foam, bulk specific gravity 0.13, particle size 1-2 mm)
F4; inorganic material-based lightweight fine aggregate (trade name “Pacific Perlite S”, bulk specific gravity 0.17, maximum particle size 0.15 mm, manufactured by Taiheiyo Materials Co., Ltd.)
G1: Styrene butadiene polymer dispersion (trade name “Pacific CXB”, manufactured by Taiheiyo Materials Co., Ltd.)
G2; acrylic styrene re-emulsified powder resin (trade name “LL512”, manufactured by Asahi Kasei Chemicals Corporation)
H1: Acrylic fiber (length: about 12mm)
H2: Steelmaking slag powder (BET specific surface area 1.5 m ² / g)
H3: Silica fume (BET specific surface area 20 m ² / g)

  [Evaluation of workability] The mortar produced was examined for crack cutting and elongation, and plastering workability was evaluated, and the thickness of the vertical wall surface and ceiling surface by plastering work was evaluated. The test methods and evaluation criteria for each item are as follows. The evaluation results are shown in Table 2.

  <Cutting off> A fresh mortar was put on a 100 × 100 × 15 cm flat surface of a 100 × 100 cm concrete plate with a commercially available metal hammer, and was applied twice to a thickness of about 4 cm. Visually inspect the finish of the painted surface, confirm that the surface is substantially smooth, and that there was almost no restorative material remaining on the used hammer. Judged to be dead.

  <Stretch elongation> The restoration material collected on the flat surface of the concrete was coated with a hammer and spread with a hammer so that the entire surface of 100 × 100 cm had a thickness of about 2 cm. Those that were spread over the entire surface within 5 minutes were judged to be “good” and the others were judged to be “bad”.

  <Thickness of wall surface> Targeting a vertical wall surface, in accordance with a method prescribed in Japan Highway Public Corporation Standard JHS 416 (Cross-section Restoration Material Quality Standard Test Method), Plaster the mortar prepared in the above, and after 24 hours, visually determine that no dripping, slipping, or peeling was found on the mortar, and that the wall thickness was good, otherwise Was judged to be “poor” on the wall thickness.

  <Thickness of the ceiling surface> In conformity with the method stipulated in Japan Highway Public Corporation Standard JHS 416 (Cross Section Restoration Material Quality Standard Test Method), the inner dimensions are vertical on a 150 x 150 x 60 mm concrete plate installed horizontally. A stainless steel frame having a height of 195 mm, a width of 140 mm, and a height of 50 mm was attached, the prepared mortar was filled into the spacer frame, and the surface of the filled mortar was leveled with a hammer. Immediately after leveling the surface horizontally, the concrete plate was inverted 180 degrees (turned over) with the frame attached. Visually, no mortar dripping or dropping or spacer peeling was judged to be “good” for the ceiling surface thickness, and the others were judged to be “poor” for the ceiling surface thickness.

[Evaluation of Cured Body] The mortar cured body was evaluated by examining the compressive strength and cracking occurrence after curing of the produced mortar by the following method. The results are shown in Table 2.
<Compressive strength characteristics> The prepared fresh mortar is filled into a mold, and a cylindrical specimen having a diameter of 5 cm and a length of 10 cm is prepared and cured for 48 hours in a constant temperature and humidity chamber at a temperature of 20 ° C. and a humidity of 80%. And then demolded. The obtained specimen was cured in water at 20 ° C. until the predetermined age until the age of 7 days. Then, the compressive strength was measured for the specimens that were further cured for 3 days and 28 days in a constant temperature and humidity chamber of 20 ° C. and 60% humidity.

  <Crack occurrence state of mortar hardened body> About the specimen used for the compressive strength test, the presence or absence of surface cracks was visually confirmed immediately before the compressive strength measurement of the 28-day curing specimen.

  From Table 2, it can be seen that all the products of the present invention have good workability, no cracks are observed after curing, and the strength development is also good.

Claims (2)

A thick mortar comprising fine aggregate made of lightweight aggregate and ordinary aggregate or fine aggregate made of lightweight aggregate, Portland cement, alkaline earth metal sulfate, expansion material, thickener and dispersant. Furthermore, the thickening mortar of Claim 1 formed by containing any 1 type (s) or 2 or more types of polymer dispersion, re-emulsification type | mold powder resin, and a fiber.