JP7583592B2 - Anchor Fixing Material - Google Patents

Description

The present invention relates to an anchor fixing material that fixes elements such as deformed bars, reinforcing bars, anchor bolts, and rock bolts into bored holes.

In the field of architecture and civil engineering, fixing materials have traditionally been used to drill holes into hard materials such as concrete, stone, bricks, blocks, and bedrock, and to secure elements such as reinforcing bars, anchor bolts, and rock bolts.

Methods of fixing the elements are divided into two types: like metal anchor bolts, where the tip of the anchor bolt expands when buried, and fixes the element in place; and adhesive materials are used to fix the elements around the bolt. Adhesive materials can be divided into organic and inorganic fixing materials.

A known inorganic anchoring material is one that contains a hydraulic substance containing cement and calcium aluminate in a destructible container made of Heatlon paper, reducing insertion resistance when driving the anchor (Patent Document 1).

Also known is a capsule for fixing elements, which contains cement, calcium aluminosilicate glass or calcium aluminate glass, gypsum, aggregate, colloidal silica, microfibrillated fibrous cellulose, water, and a setting retarder in an easily breakable container (Patent Document 2).

Furthermore, a rapid hardening cement composition for use as an anchor element fixing material containing an alkali metal carbonate, an aluminate, an inorganic compound, calcium aluminate, and a water-retentive substance is known (Patent Document 3).

When the inorganic fixing materials described in Patent Documents 1 to 3 are fixed in the boreholes, the cement composition containing cement, calcium aluminate, and aggregate is allowed to absorb water. However, in the case of Patent Document 2 in particular, the water and aggregate may be stored in a mixed state for a long period of time, causing the aggregate and water to separate, preventing the fixing material from being mixed uniformly, and the element may not be completely fixed in the borehole.

JP 2011-079708 A JP 2009-114000 A JP 2006-335586 A

As mentioned above, it is practically necessary for the fixing material to be mixed uniformly, but considering the expansion of applications to various construction sites, fixing materials that are easy to apply to holes on the top surface and in the horizontal direction, have good pumpability, and can achieve good adhesion without flowing out of the holes during construction will become more important in the future.

The present invention aims to provide an anchor fixing material that has the plasticity to not flow out of holes that are horizontally or upwardly filled, and is easy to handle so that it can be pumped with a pump or the like, and that fixes the anchor element inserted into the insertion hole with high adhesion without the fixing material flowing out during construction.

As a result of extensive research, the inventors discovered that the above problems could be solved by using an expanding agent, a plasticizer, and cement containing specific components, and thus completed the present invention.

The present invention is as follows.
[1] An anchor fixing material comprising cement, an expanding agent, and a plasticizer, the expanding agent containing eelimite and ternesite, and a mass ratio of the eelimite to the ternesite (eelimite/ternesite) being 1 to 40.
[2] The anchor fixing material according to [1], wherein the plasticizer contains SiO ₂ and the amount of the SiO ₂ is 85 parts by mass or more per 100 parts by mass of the plasticizer.
[3] The anchor fixing material according to [1] or [2], wherein the plasticizer has a BET specific surface area of 5 m ² /g to 70 m ² /g.

The anchor fixing material of the present invention, which contains cement, an expanding agent, and a plasticizer, is mixed with water to have plasticity that prevents it from flowing out even when filled into holes in the horizontal or upward direction, while also being easy to handle and capable of being pumped with a pump or the like. When fixing an anchor element inserted into an insertion hole, the fixing material does not flow out during construction, and the anchor element can be fixed tightly.

The following describes in detail an embodiment of the present invention, but the present invention is not limited to this embodiment. In this specification, "parts" and "%" are based on mass unless otherwise specified.

[cement]
The cement used in the present invention typically includes various types of commercially available Portland cement, such as normal, early strength, medium heat, low heat, and extra early strength Portland cement, various mixed cements in which fly ash or blast furnace slag is mixed with these Portland cements, and ecocement, and these can also be used in a finely powdered form.

[Expansion material]
The expanding agent used in the present invention contains eelimite and ternesite. The expanding agent can fix the anchor element with high adhesion. The details are explained below.

(Elimite)
Eelimite is a mineral represented by the formula 3CaO.3Al _{2 O} 3.CaSO ₄ , which is hydrated in the presence of gypsum or the like to form ettringite (3CaO.Al _{2 O 3.3CaSO} 4.32H ₂ O), which contributes to improving early strength.

From the viewpoint of reactivity, the particle size of Elimite is preferably 4,500 to 12,000 cm ² /g, and more preferably 5,000 to 10,000 cm ² /g, in terms of Blaine specific surface area.

The content of Elimite is preferably 5 to 35 parts, more preferably 8 to 30 parts, per 100 parts of expanding agent. A content of 5 to 35 parts can improve initial strength.

(Ternesite)
Ternesite is a mineral represented by _{5CaO.2SiO2.SO3} , _and promotes the hydraulic reaction of eelimite. Moreover, since ternesite itself hardly reacts, it is presumed to play a role like a filler and improve fluidity retention. Therefore, flow-down can be reduced.

The content of ternesite is preferably 0.05 to 20 parts, more preferably 0.1 to 15 parts, and even more preferably 1 to 10 parts, per 100 parts of expanding agent. By having a content of 0.05 to 20 parts, it is possible to improve both the hardening acceleration and the fluidity retention of Elimite.

Here, the mass ratio of eelimite to ternesite (eelimite/ternesite) is preferably 1 to 40, more preferably 4 to 35, and even more preferably 5 to 30. If the mass ratio is less than 1, good expansion properties, particularly a large rate of length change, may not be obtained when applied as an expansion agent. Also, if the mass ratio exceeds 40, it becomes difficult to obtain the hardening-promoting effect of ternesite on eelimite.

The expanding agent containing eelimite and ternesite can be produced, for example, by blending CaO raw material, Al ₂ O ₃ raw material, SiO ₂ raw material, and CaSO ₄ raw material, mixing and grinding them, then firing them at 1100 to 1600°C to synthesize clinker, and grinding them to a Blaine specific surface area of about 2000 to 6000 cm ² /g. The mass ratio of eelimite to ternesite can be adjusted by the ratio of the raw materials. Examples of CaO raw materials include limestone and slaked lime, examples of Al ₂ O ₃ raw materials include bauxite and aluminum ash, etc., examples of SiO 2 raw materials include silica stone, etc., and examples of CaSO ₄ raw materials include gypsum dihydrate, gypsum hemihydrate, and anhydrous gypsum.

(Plasticizer)
The plasticizer used in the present invention contains _SiO2 as a chemical component, and is preferably 85 parts or more, more preferably 90 parts or more, per 100 parts by mass of the plasticizer. By being 85 parts or more, high plasticity can be exhibited. The "plasticization" referred to here refers to the property of preventing the fixing material from overflowing during application while maintaining non-fluidity after application. This property can provide the effect of making it easier to handle (facilitating processing) when pumping or filling holes. Here, the _SiO2 content in the plasticizer can be measured by fluorescent X-ray diffraction.
Plasticizers containing _SiO2 include, for example, silica fume.

The BET specific surface area of the plasticizer is preferably 5 m ² /g to 70 m ² /g, and more preferably 10 m ² /g to 60 m ² /g. If the specific surface area (BET) is 5 m ² /g or more, sufficient plasticity can be easily ensured, and if it is 70 m ² /g or less, pumping can be improved.

In 100 parts by mass of the anchor fixing material consisting of cement, expanding agent, and plasticizer, the amount of cement is preferably 85 to 98 parts, and more preferably 90 to 95 parts. The amount of expanding agent is preferably 0.5 to 8 parts, and more preferably 1 to 5 parts. Furthermore, the amount of plasticizer is preferably 0.5 to 10 parts, and more preferably 2 to 8 parts. Having the above components within the specified range in 100 parts by mass of the anchor fixing material results in good adhesion, ease of handling, and plasticity.

In addition to aggregates such as sand and gravel, the anchor fixing material of the present invention can contain one or more of the following: water reducing agents, high-performance water reducing agents, air-entraining water reducing agents, high-performance air-entraining water reducing agents, fluidizing agents, antifoaming agents, thickening agents, rust inhibitors, antifreeze agents, shrinkage reducing agents, polymer emulsions and setting regulators, as well as cement hardening agents, clay minerals such as bentonite and zeolite, and anion exchangers such as hydrotalcite, within a range that does not substantially impair the object of the present invention.

The anchor fixing material of the present invention can be mixed with water and filled into the drilled hole into which the anchor is to be inserted. However, for example, in construction conditions where a large amount of material is used, the anchor fixing material can be mixed with water in a construction mixer or the like, pumped, and the material can be filled into the hole before the anchor is inserted.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these.

(Experimental Examples 1 to 6)
Of the 100 parts by mass of anchor fixing material consisting of cement, an expansion agent, and a plasticizer, 90 parts by mass of cement, 5 parts by mass of expansion agent, and 5 parts by mass of plasticizer were used, and a cement paste with a water/anchor fixing material ratio of 40% was prepared in a room at 20°C, and the compressive strength, length change rate, and flow were measured. The results are shown in Table 1.

(Materials used)
Water: tap water Cement: ordinary Portland cement, commercially available Plasticizer: silica fume with _SiO2 content of 99.3%, BET specific surface area 45 ^m2 /g
Expansion agent: CaO raw material (limestone), _{Al2O3 raw} material (bauxite), _SiO2 raw material (silica stone), and _CaSO4 raw material (anhydrous gypsum) were mixed, crushed, and then fired at 1,200°C to synthesize clinker. The clinker was then crushed in a ball mill to a Blaine specific surface area of 3,000 ^cm2 /g to produce an expansion agent with the composition shown in Table 1.
The mineral composition was calculated based on the chemical composition determined from X-ray fluorescence and the results of powder X-ray diffraction identification.

(Test Method)
Compressive strength: Test specimens of 4 x 4 x 16 cm were prepared in accordance with JIS R 5201, and the compressive strength at an age of 7 days (7d) was measured.
- Length change: Measured and evaluated at 7 days (7d) in accordance with JIS A 6202. If the shrinkage is large, the adhesion and fixation between the anchor and the existing structure cannot be sufficiently secured after construction, and conversely, if the expansion is too large, the existing structure may be destroyed. Therefore, the evaluation method was ◯ (expansion strain is -200×10 ^-6 to 1000×10 ^-6 ) and × (expansion strain is less than -200×10 ^-6 ).
・Flow: In accordance with JIS R 5201-2015 "Physical Testing Methods for Cement," the flow value was measured immediately after the flow cone was removed from the mixture and after 15 hits. The material was then left to stand for 60 minutes and similar measurements were performed to confirm the change in flow. The static state is the plasticity of the material, and 120 mm or less is desirable. After 15 hits, it is the pumpability, and 160 mm or more is desirable.

Table 1 shows that by using an expansive material with a specific mineral ratio, it has good flow retention and can achieve sufficient expansion to set the holes and anchors in place after hardening.

(Experimental Examples 7 to 13)
A cement paste with a water/anchor material ratio of 40% was prepared in a room at 20°C using 90 parts by mass of cement, 5 parts by mass of expansion agent, and 5 parts by mass of plasticizer out of 100 parts by mass of the anchor fixing material, and measurements were taken of compressive strength, flow immediately after mixing (immediately after the flow cone was removed and after 15 strokes), and length change. The method of determining the length change was the same as in Experiments 1 to 6. As a comparative example without the addition of plasticizer, a cement paste with a water/anchor fixing material ratio of 40% was similarly tested using 95 parts by mass of cement and 5 parts by mass of expansion agent out of 100 parts by mass of the anchor fixing material. The test results are shown in Table 2.

(Materials used)
Water: tap water Cement: ordinary Portland cement, commercially available product Expansion agent: 30 parts of Elimite, 1.5 parts of Ternesite (No. 4 used in Experiment 1)
Plasticizer A: Silica fume with _SiO2 content of 84.1%, specific surface area (BET) of 20 ^m2 /g
Plasticizer B: Silica fume with _SiO2 content of 90.9%, specific surface area (BET) of 33 ^m2 /g
Plasticizer C: Silica fume with _SiO2 content of 95.8%, specific surface area (BET) of 18 ^m2 /g
Plasticizer D: Silica fume with _SiO2 content of 98.5%, specific surface area (BET) of 74 ^m2 /g
Plasticizer E: Silica fume with _SiO2 content of 98.7%, specific surface area (BET) of 20 ^m2 /g
To the plasticizer: silica fume with a _SiO2 content of 99.3%, specific surface area (BET) of 45 ^m2 /g (same as the plasticizer used in Experimental Example 1).

From Table 2, it can be seen that by using a plasticizer having a specific _SiO2 and a specified specific surface area, good plasticity and sufficient flow spread at 15 strokes can be obtained.
In the comparative example, Test No. 13, the flow value immediately after the flow cone was removed was large, so there was a high possibility that the material would flow out during construction in the horizontal or upward direction.
The evaluation by measuring the change in length was ◯ (expansion strain was −200×10 ⁻⁶ to 1000×10 ⁻⁶ ).

The anchor fixing material of the present invention can be suitably used in the fields of civil engineering and construction.

Claims (1)

The composition comprises a cement, an expanding agent, and a plasticizer, the expanding agent containing eelimite and ternesite, and a mass ratio of the eelimite to the ternesite (eelimite/ternesite) is 1 to 40 ;
The plasticizer contains SiO ₂ , the amount of the SiO ₂ being 85 parts by mass or more per 100 parts by mass of the plasticizer, and the anchor fixing material is silica fume having a BET specific surface area of 5 m ² /g to 70 m ² /g.