JP6997579B2 - Mortar composition and mortar - Google Patents

Description

The present invention relates to mortar compositions and mortars.

The mortar that fills the hollow part of the structure is used for fixing the upper and sewer pipes in the shield tunnel, filling for building a horizontal plane, and filling the gap between the propulsion pipe and the ground in the secondary construction of the shield method. It is used for filling the inside of pipes necessary for burying water pipes that can no longer be used. Since such mortar may be pumped over a long distance, it is required to suppress the occurrence of material separation (bleeding) in the process. Therefore, clay-based minerals such as bentonite, which have the property of retaining a large amount of water, are often used in the mortar used for filling cavities in anticipation of suppressing material separation (for example, Patent Document 1, Patent Document 1, Patent Document 2 etc.).

Japanese Unexamined Patent Publication No. 2007-297274 Japanese Unexamined Patent Publication No. 2013-049590

However, bentonite is vulnerable to alkali, and when it is premixed with cement, if the alkali elutes from the cement due to the moisture in the air over time, the water immobilization ability of bentonite decreases, and there is a concern that bleeding is likely to occur. Therefore, there is a demand for mortar using a material that replaces bentonite.

An object of the present invention is to provide a new mortar composition and mortar in which the occurrence of bleeding is suppressed.

As a result of diligent studies on the above-mentioned problems, the present inventor has found that by using a lightweight aggregate in addition to the inorganic powder, the occurrence of bleeding can be suppressed by its water-immobilizing ability, and the invention has been completed.

That is, the present invention provides the following [1] to [5].
[1] It contains hydraulic cement, inorganic powder, and lightweight aggregate, and the content of the inorganic powder is 60 to 95 parts by mass with respect to 100 parts by mass of the total of hydraulic cement and inorganic powder, and the lightweight bone. A mortar composition in which the content of the material is 8 to 35 parts by mass with respect to a total of 100 parts by mass of the hydraulic cement and the inorganic powder.
[2] The mortar composition of [1], wherein the inorganic powder is at least one powder selected from the group consisting of calcium carbonate, fly ash, silica fume, blast furnace slag and silica stone.
[3] The mortar composition of [1] or [2], wherein the bulk specific gravity of the lightweight aggregate is 0.05 to 0.8 kg / L.
[4] The mortar composition according to any one of [1] to [3], further comprising a thickener.
[5] The mortar composition according to any one of [1] to [4] and water are contained, and the content of water is 50 to 100 parts by mass with respect to 100 parts by mass in total of the hydraulic cement and the inorganic powder. There is a mortar.

According to the present invention, it is possible to provide a new mortar composition and mortar in which the occurrence of bleeding is suppressed.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited thereto.

The mortar composition of the present embodiment contains hydraulic cement, an inorganic powder, and a lightweight aggregate.

Various hydraulic cements can be used, and examples thereof include various Portland cements such as ordinary, early-strength, ultra-fast-strength, low-heat and moderate heat, eco-cement, and quick-hardening cement. As the hydraulic cement, one type may be used alone, or two or more types may be used in combination.
Some quick-hardening cements contain calcium sulfates as an active ingredient, and contain 11CaO ・ 7Al ₂ O ₃・ CaX ₂ (X indicates a halogen atom) or 3CaO ・ 3Al ₂ O ₃・ CaSO ₄ (auyne). Those contained as active ingredients are also included.
Further, a quick-hardening admixture prepared by blending calcium aluminates and an inorganic salt such as gypsum, which is added to Portland cement, can also be used as the quick-hardening cement. The calcium aluminates may be either crystalline or amorphous, or may be a mixture of crystalline and amorphous.

The inorganic powder is a powder of an inorganic substance different from the above hydraulic cement. Examples of the inorganic powder include powders of calcium carbonate, fly ash, silica fume, blast furnace slag, silica stone and the like. Among these, calcium carbonate, fly ash, and silica fume are preferable, calcium carbonate and fly ash are more preferable, and calcium carbonate is further preferable, from the viewpoint of economy. As the inorganic powder, one type may be used alone, or two or more types may be used in combination. The calcium carbonate is not particularly limited as long as it contains calcium carbonate as a main component, and may be chemically purified calcium carbonate or may be prepared by crushing limestone into fine powder. ..

The content of the inorganic powder is 60 to 95 parts by mass, preferably 65 to 95 parts by mass, and more preferably 70 to 90 parts by mass with respect to 100 parts by mass of the total of the hydraulic cement and the inorganic powder. When the content of the inorganic powder is within the above range, it is easy to secure the pot life while maintaining the strength at the time of curing, and it is easy to suppress the increase in heat of hydration.

The lightweight aggregate is not particularly limited, and for example, pearlite, which is an inorganic foamable aggregate obtained by firing and foaming obsidian, pearl rock, etc., fly ash balloons generated in a thermal power plant, and foamed glass particles (glass balloon). ) Etc. can be mentioned. As the lightweight aggregate, one type may be used alone, or two or more types may be used in combination. The particle size of the lightweight aggregate is preferably 0.05 to 5 mm, more preferably 0.1 to 3 mm, further preferably 0.1 to 1.5 mm, and particularly preferably 0.1 to 1 mm. When the particle size of the lightweight aggregate is within the above range, it is easy to suppress the occurrence of bleeding and it is easy to secure better fluidity.

The lightweight aggregate preferably has a bulk specific gravity of 0.05 to 0.8 kg / L, more preferably 0.07 to 0.5 kg / L, and further preferably 0.1 to 0.3 kg / L. preferable. When the bulk specific gravity is in the above range, the unit volume mass of the mortar is made lighter, the occurrence of bleeding is easily suppressed, the pumping by the mortar pump is easier, and it is easy to secure better fluidity. Here, the bulk specific density refers to the bulk specific density of the lightweight aggregate when one type of lightweight aggregate is used, and refers to the bulk specific gravity of a mixture of lightweight aggregates when two or more types are used together.

The content of the lightweight aggregate is 8 to 35 parts by mass, preferably 10 to 30 parts by mass, more preferably 10 to 25 parts by mass, and 10 to 20 parts by mass with respect to 100 parts by mass in total of the water-hardening cement and the inorganic powder. By mass is even more preferred, 12 to 20 parts by mass is even more preferred, and 12 to 17 parts by mass is particularly preferred. When the content of the lightweight aggregate is within the above range, it is easy to suppress the occurrence of bleeding.

The mortar composition of the present embodiment may contain a thickener. The type of thickener is not particularly limited, and examples thereof include a cellulose-based thickener, an acrylic-based thickener, a guar gum-based thickener, and a starch-based thickener. The thickener is preferably a cellulosic thickener, and examples thereof include carboxymethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. As the thickener, one type may be used alone, or two or more types may be used in combination. The molecular weight of the thickener may be adjusted according to its use. For example, a high molecular weight thickener has more excellent material separation resistance when used in an environment with water.

The content of the thickener is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass, and 0.05 to 0.5 parts by mass with respect to 100 parts by mass of the total of the hydraulic cement and the inorganic powder. The mass part is more preferable. When the content of the thickener is within the above range, the material is more difficult to separate, bleeding is easily suppressed, and better fluidity is easily ensured.

The mortar composition of the present embodiment may contain a water reducing agent. The water reducing agent includes a high performance water reducing agent, a high performance AE water reducing agent, an AE water reducing agent and a fluidizing agent. Examples of such a water reducing agent include water reducing agents specified in JIS A 6204: 2011 “Chemical admixture for concrete”. Examples of the water reducing agent include a polycarboxylic acid-based water reducing agent, a naphthalene sulfonic acid-based water reducing agent, a lignin sulfonic acid-based water reducing agent, a melamine-based water reducing agent, and an acrylic water-reducing agent. Among these, a melamine-based water reducing agent is preferable. As the water reducing agent, one type may be used alone, or two or more types may be used in combination.

The content of the water reducing agent is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass, and 0.05 to 0.5 parts by mass with respect to 100 parts by mass of the total of the hydraulic cement and the inorganic powder. The portion is more preferable. When the content of the water reducing agent is within the above range, it is easy to suppress bleeding and it is easy to secure better fluidity.

In the mortar composition of the present embodiment, various admixtures may be used as long as the effects of the present invention are not impaired. Examples of the admixture include foaming agents, swelling agents, gypsum, quick-hardening agents, waterproofing agents, rust preventives, shrinkage reducing agents, water retention agents, pigments, water repellents, and efflorescence inhibitors.

The mortar composition of the present embodiment can be prepared by mixing with a kneading device usually used, and the device is not particularly limited. Examples of the kneading device include a grout mixer, a hobert mixer, a hand mixer, a tilting mixer, a twin-screw mixer, and the like.

The mortar composition of the present embodiment can be prepared as a mortar by mixing with water, and the content of the water may be appropriately adjusted according to the intended use. The water content is preferably 50 to 100 parts by mass, more preferably 60 to 90 parts by mass, and even more preferably 65 to 85 parts by mass with respect to 100 parts by mass of the total of the hydraulic cement and the inorganic powder. When the water content is within the above range, it is easy to suppress bleeding and it is easy to secure better fluidity.

The mortar of the present embodiment preferably has a unit volume mass of 0.8 to 1.5 kg / L, more preferably 0.85 to 1.4 kg / L, and further preferably 0.9 to 1.3 kg / L. preferable. When the unit volume mass is within the above range, the weight is even lighter, so that the influence of the mortar's own weight is less likely to occur, and it is difficult to apply a load to the construction site.

The preparation of the mortar of the present embodiment can use the same kneading equipment as a normal mortar, and is not particularly limited. As the kneading tool, for example, the above-mentioned one can be used.

Since the mortar composition and the mortar of the present embodiment are less likely to cause bleeding and are lightweight, they can be used not only in a normal casting place but also in a higher casting place. The mortar composition and mortar of the present embodiment can be appropriately selected depending on the fluidity (viscosity). For example, filling in a narrow space such as a gap between a concrete structure and a steel plate, filling in a pipe, and shielding. It can be suitably used for filling various cavities such as backfilling in the construction method, filling the back of the structure, filling the cavity under the floor of the structure, and filling the void in the lower part of the road.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

The materials used in the examples are as follows.
Cement: Ordinary Portland cement (manufactured by Taiheiyo Cement)
Calcium carbonate: Fine limestone powder (manufactured by Kondo Lime Industry Co., Ltd.)
Fly ash: Fly ash (manufactured by Taiheiyo Cement)
Lightweight aggregate: pearlite-based pearlite (manufactured by Pacific pearlite), particle size 0.6 mm or less Thickener: hydroxypropylmethylcellulose-based (manufactured by Shin-Etsu Chemical Co., Ltd.)
Water reducing agent: Melamine sulfonic acid-based water reducing agent (manufactured by BASF Pozoris)

[Making mortar]
In an environment of 20 ° C., various materials were added to a cylindrical container at the blending ratios shown in Table 1, water was added, and the mixture was kneaded with a hand mixer for 60 seconds to prepare a mortar. The amount of water was 75 parts by mass with respect to 100 parts by mass of the total of cement and inorganic powder.

Each item was evaluated by the following method. The evaluation results are shown in Table 1.
[Measurement of bleeding rate]
The bleeding rate 3 hours after kneading was measured according to JIS A 1123: 2012 “Concrete bleeding test method”.
[Measurement of flow value]
JIS R 5201: 2015 "Physical test method for cement" 12. The flow value was measured for the mortar immediately after kneading in accordance with the flow value (without falling motion) after removing the flow cone using the flow cone specified in the flow test.
[Measurement of J funnel flow down value]
The J14 funnel flow time was measured in accordance with the JSCE standard JSCE-F 541-2013 "Fluidity test method for filled mortar (draft)".
[Measurement of unit volume mass]
The unit volume mass was measured in accordance with JIS A 1171: 2016 “Test Method for Polymer Cement Mortar” 6.4 Unit Volume Mass Test.

From Table 1, bleeding occurs in the mortar composition in which 8 to 35 parts by mass of lightweight aggregate is blended in addition to 60 to 95 parts by mass of the inorganic powder with respect to 100 parts by mass of the hydraulic cement and the inorganic powder in total. Is remarkably suppressed, and it can be seen that the filling property into the hollow portion of the structure is excellent. Although the mortar compositions of Examples 4 and 8 were closed in the J14 funnel flow value test, they can be sufficiently used in, for example, pumping filling, vibration filling, and the like.

Claims (5)

Contains hydraulic cement, limestone fine powder, lightweight aggregate having a bulk specific density of 0.05 to 0.8 kg / L, and a water reducing agent .
The content of the limestone fine powder is 60 to 95 parts by mass with respect to a total of 100 parts by mass of the hydraulic cement and the limestone fine powder .
A mortar composition for filling a cavity, wherein the content of the lightweight aggregate is 8 to 35 parts by mass with respect to a total of 100 parts by mass of the hydraulic cement and the fine powder of limestone . The mortar composition for filling a cavity according to claim 1, wherein the content of the water reducing agent is 0.01 to 2 parts by mass with respect to 100 parts by mass in total of the hydraulic cement and the fine powder of limestone . The mortar composition for filling a cavity according to claim 1 or 2, further comprising a thickener in an amount of 0.01 to 2 parts by mass with respect to a total of 100 parts by mass of hydraulic cement and limestone fine powder . The mortar composition for filling a cavity according to any one of claims 1 to 3 and water are included.
A mortar having a water content of 50 to 100 parts by mass with respect to a total of 100 parts by mass of the hydraulic cement and the limestone fine powder . The mortar according to claim 4, wherein the unit volume mass is 0.8 to 1.5 kg / L.