JP2021123507A - Highly durable back-filling grout material - Google Patents

Abstract

To provide a back-filling grout material having enhanced initial strength in 2 hour material age and having sufficient long-age strength, thereby having excellent durability to repeated loads.SOLUTION: This invention relates to a highly durable back-filling grout material, characterized in that the fiber is a dissociative bundled fiber which is kept in a converged state during dry blend and is defibrated into single fibers after the dry blend. Preferably, the fiber is a dissociative bundled fiber in which, when the fiber is kneaded with the grout material and water to obtain a grout, an aggregation ratio 2 minutes after starting the kneading is 20% or less. In the highly durable back-filling grout material, flow-down time of the grout kneaded in a ratio (W/B) between water and the grout material of 35-65%, measured by JA funnel flow test, is 30 seconds or less; and compression strength in 2 hour material age of the grout after hydration hardening is 2 N/mm2 or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to a backfill grout material that is introduced into a gap under a concrete pavement plate and has high durability against powdering due to repeated loading and excellent initial strength at a material age of 2 hours.

In the construction of concrete pavement slabs such as precast RC pavement slabs and precast PC pavement slabs, spacers are usually installed between the pavement slab and the upper surface of the roadbed in order to adjust the level in the horizontal direction in order to install the pavement slab. , A gap of about 1 mm to 30 mm is formed between the upper surface of the roadbed and the lower surface of the pavement slab. A backfill grout is injected into this gap to form a structure that uniformly transmits the weight of the concrete pavement slab and the load generated by the running of traffic to the roadbed.

Further, it is known that the concrete pavement slab constructed on the soft ground is slightly subsided because the ground is compacted by the weight of the concrete pavement slab and the load over time. In order to restore the height of the subsided pavement surface, the concrete pavement slab may be lifted and adjusted for non-landing, and backfill grout may be injected into the gap created between the lower surface and the roadbed.

In such concrete pavement work, in the pavement of facilities such as airport aprons, quick construction is required because the construction is time-constrained, and quick hardness is also required for the backfill grout so as to cope with it. In addition, resistance to powdering due to repeated fatigue due to traffic load is also required.

As the backfill grout material, Japanese Patent Application Laid-Open No. 8-290951 (Patent Document 1) describes a backfill grout material containing cement, calcium aluminate, gypsum, and alumina dross as main components. In this backfill grout material, calcium aluminate and gypsum accelerate the development of initial strength, and alumina dross suppresses long-term strength and reduces volume reduction.

However, although the backfill grout material of Patent Document 1 has quick hardening properties, it does not have sufficient resistance to powdering due to repeated loading. Therefore, as described in Japanese Patent Application Laid-Open No. 2011-144103 (Patent No. 5311584: Patent Document 2), a backfill grout material having improved fatigue durability has been developed. This backfill grout material is mainly composed of cement and fast-hardening material and is blended with inorganic or organic short fibers. The fast-hardening material is blended to accelerate the development of initial strength and short fibers are blended. Increases resistance to powdering due to repeated loading.

The backfill grout material of Patent Document 2 contains short fibers to improve powder resistance, but on the other hand, a large amount of quick-hardening material is blended in order to obtain quick-hardening property. Specifically, a large amount of quick-hardening material ranging from 25% by mass to 40% by mass is blended with respect to cement. However, when the amount of the quick-hardening material is large, the powder resistance to repeated loading tends to decrease. On the other hand, if the amount of the quick-hardening material is small and the time required for curing is too long, material separation is likely to occur, and the short fibers are biased toward the upper surface of the grout, and sufficient fatigue durability cannot be obtained. Therefore, there has been proposed a backfill grout material in which the content of the quick-hardening material is 1 to 6% by mass to ensure appropriate fluidity and time until gelation (Japanese Unexamined Patent Publication No. 2019-11233: Patent Document 3). ). However, this backfill grout material has a low compressive strength at the age of 2 hours.

Further, a grout material containing a mineral powder filler (Patent No. 3372012: Patent Document 4) and a grout composition containing calcium aluminosilicate, gypsum, etc. (Japanese Patent Laid-Open No. 2004-210557: Patent Document 5) are known. However, the durability is low in both cases.

On the other hand, as a fiber material for reinforcing cement, short reinforcing fibers in which genbuiwa fibers are bundled with a resin are known (Japanese Patent Laid-Open No. 2012-56780), and a fiber bundle in which a large number of single fibers are bundled is an isocyanate compound. A reinforcing fiber material that is hardened with a resin and whose surface is treated with an epoxy resin is known (International Publication No. 2016-117435). However, since these reinforcing fiber materials are made by bundling single fibers and hardening them with a resin, when they are blended in the grout, the fiber materials are not dispersed in the single fibers and are present in the grout as an aggregate, so that they are reinforced. The effect may not be sufficient.

Japanese Unexamined Patent Publication No. 8-290951 Japanese Unexamined Patent Publication No. 2011-144103 (Patent No. 5311584) Japanese Unexamined Patent Publication No. 2019-11233 Japanese Patent No. 3372012 Japanese Unexamined Patent Publication No. 2004-210557 Japanese Unexamined Patent Publication No. 2012-56780 International Publication No. 2016-117435

The backfill grout material of the present invention solves the above-mentioned conventional problems, and the type and amount of fibers to be blended in the grout are examined, and the backfill grout material of Patent Document 3 has a material age of 2 hours. Provides a backfill grout that enhances the initial strength of the grout, has sufficient long-term strength, and has excellent fatigue durability against repeated loads. In addition, in this invention, the powder which does not add water is called a backfill grout, and the backfill grout which is hydrated and hardened including the liquid state until water is added and kneaded and hardened is called a backfill grout. The backfill grout formed by the backfill grout material of the present invention is referred to as the backfill grout of the present invention.
Further, the production of grout material by mixing materials such as fibers and cement excluding water is called dry mixing, and the process of adding water to powdered grout material and kneading to produce grout is called kneading.

The present invention relates to a backfill grout material or the like having the following constitution.
[1] A backfill grout material for concrete pavement slabs containing cement as a main component and containing a quick-hardening material, fibers, a water reducing agent, and a coagulation adjusting agent. A highly durable backfill grout material characterized by being a dissociable focused fiber that later defibrate into a single fiber.
[2] The above-mentioned fiber is a dissociative focusing fiber having an agglutination rate of 20% or less 2 minutes after the start of kneading when the grout material and water are kneaded to form a grout. Highly durable backfill grout material.
[3] The highly durable backfill grout according to the above [1] to the above [2], wherein the content of the dissociative focused fibers is 0.05% by volume or more and less than 0.40% by volume with respect to the grout. Material.
[4] The content of the dissociative focused fibers is 0.05% by volume or more and less than 0.40% by volume with respect to the grout, and the content of the focused fibers having a fiber length of 6 mm or more is 0.1% by volume. The highly durable backfilling grout material according to the above [1] to the above [3], which is less than the above.
[5] The highly durable backfill grout material according to any one of the above [1] to the above [4], wherein the dissociative focusing fiber is an aramid fiber.
[6] The highly durable backfill grout material according to any one of the above [1] to [5], wherein the content of the fast-hardening material is 8% by mass or more and 40% by mass or less with respect to the cement.
[7] The above [1] to the above [7], which contains a re-emulsified powder resin, and the content of the re-emulsified powder resin is 3.0% by mass or more and 6.0% by mass or less in the internal division of the backfill grout material. Highly durable backfill grout material according to any one of 6].
[8] The highly durable backfill grout material according to the above [7], wherein the re-emulsified powder resin is an acrylic re-emulsified powder resin.
[9] The content of the water reducing agent is 0.05% by mass or more and 1.0% by mass or less with respect to the cement, and the content of the coagulation adjusting agent is 0.00 to 3.0% by mass with respect to the cement. The highly durable backfill grout material according to any one of the above [1] to the above [8], which is less than or equal to%.
[10] The flow time of the JA grouting flow test of the grout obtained by kneading the above grout material at a water grout material ratio (W / B) of 35 to 65% is 30 seconds or less, and the grout material age after hydration hardening 2 The highly durable backfill grout material according to any one of the above [1] to the above [9], which has a compressive strength of 2 N / mm ^{2 or more over time.}
[11] High durability characterized by having ^{a compressive strength of 20 N / mm 2} or more at 7 days of age formed by the backfill grout material according to any one of the above [1] to [10]. Backfill grout.

[Specific explanation]
The backfill grout material of the present invention (hereinafter referred to as a grout material) is a backfill grout material for concrete pavement slabs containing cement as a main component, a fast-hardening material, fibers, a water reducing agent, and a coagulation adjusting agent. The focused fiber is a highly durable backfill grout material characterized by being a dissociable focused fiber that is defibrated into a single fiber by dry mixing.

The grout material of the present invention contains cement as a main component. As the cement, ordinary Portland cement, early-strength Portland cement, moderate heat Portland cement, blast furnace cement, fly ash cement, white cement and the like can be used.

The grout lumber of the present invention includes a fast-hardening lumber. Fast hardwood is _a mixture of _C 12 _{A 7} calcium aluminate ground product, such as (Blaine specific surface area 4000~6000cm ² / g) and anhydrite (Blaine specific surface area 5000~12000cm ² / g), ultra rapid setting cement, alumina cement Etc. can be used. The fast-hardening material composed of a mixture of pulverized calcium aluminate and anhydrous gypsum contains approximately 40:60 to 60:40 mass ratio of pulverized calcium aluminate and anhydrous gypsum. As a commercially available product, for example, Coca Ace Super (trade name) manufactured by Mitsubishi Materials Corporation can be used.

The content of the quick-hardening material is preferably 8% by mass or more and 40% by mass or less with respect to the cement. When the content of the fast-hardening material is in the above range, the compressive strength of the grout for 2 hours can be increased to ^{2 N / mm 2 or more.} If the content of the fast-hardening material is less than 8% by mass, it is difficult to increase the compressive strength at 2 hours of age to the above strength. On the other hand, if the content of the quick-hardening material exceeds 40% by mass, the cost of the raw material increases, which is not preferable.

The grout material of the present invention contains fibers, which are dissociative focused fibers. The focused fiber is a bundle of fibers in which a plurality of single fibers are integrated, and the dissociative focused fiber is a focused fiber that is defibrated into a single fiber after dry mixing with cement or the like, and further, a grout material. Is a focused fiber having a property of being hard to aggregate when kneaded with water. Specifically, for example, it is a focused fiber having an agglutination rate S of 20% or less after 2 minutes of kneading.

The agglutination rate S is a mass ratio of the amount of agglutination generated during kneading to the total amount of the blended fibers, and is represented by, for example, the following formula [1]. In the present invention, the agglomerate is a residue on the sieve having a sieve opening of 4 mm.
Agglutination rate S = (G / M) × 100 ・ ・ ・ [1]
(M is the total mass of the blended fiber, G is the amount of agglutinating substance)

Dissociative focused fibers are not hardened with a binder such as resin, but are dried in a bundle with water or oil soaked between a plurality of single fibers, and integrated by intermolecular force or the like. It is a thing. As the oil, for example, straight silicone oil, modified silicone oil and the like are used. The oil content (oil content) is preferably 1.0% by mass or more and 5.0% by mass or less with respect to the fiber.

The focused fibers treated with oil are defibrated into single fibers after dry mixing of grout material, but since the fiber surface has water repellency, this water repellency causes water repellency in the presence of water during kneading with water. It has the property of dispersing fibers in the grout without being entangled with each other. Therefore, agglutination (lump) is unlikely to occur during kneading, and the agglutination rate S is small. On the other hand, the focused fibers that have not been treated with oil have good hydrophilicity because they contain water instead of oil, easily form agglutinates during kneading, and have a large agglutination rate S. The focusing fiber used in the present invention is mainly an oil-treated focusing fiber, and has a small agglutination rate because it is difficult to agglutinate during kneading.

As described above, the dissociative focusing fibers used in the present invention are difficult to agglutinate because they maintain a focused state during dry mixing, and are less likely to agglutinate due to the water repellency of oil even when kneading with water, for example. It is a focused fiber having an agglutination rate S of 20% or less. The dissociative focused fibers used in the present invention are not limited to those treated with oil as long as the agglutination rate S is 20% or less.

The dissociative focused fiber is, for example, a bundle of about 300 to about 1200 single fibers having a fiber diameter of about 10 to about 30 μm and integrated. The integrated shape of the focusing fibers may be a flat plate shape or a rod shape. By including such dissociative focused fibers, the focused fibers are less likely to be defibrated into single fibers to form lumps in the grout, so that the strength of the grout is increased and the fatigue durability is improved.

The dissociative focused fiber is preferably a short fiber having a fiber length of 2 to 4 mm. A single fiber having an appropriate length may be focused to form a focused fiber, and then cut to a fiber length of 2 to 4 mm. By using the focused fibers having a fiber length of 2 to 4 mm, there is little lumps in the fibers when the grout is kneaded, and the fluidity of the fresh grout is kept good.

The content of the dissociative focused fibers is preferably 0.05% by volume or more and less than 0.40% by volume, and more preferably 0.15% by volume or more and 0.25% by volume or less with respect to the grout. If the content of the focused fibers is less than 0.05% by volume, the reinforcing effect becomes insufficient, and if it exceeds 0.40% by volume, the fluidity of the fresh grout decreases, which is not preferable. Further, the focused fiber is preferably a short fiber having a fiber length of 2 to 4 mm, and the amount of the fiber having a fiber length of 6 mm or more is preferably less than 0.1% by volume. Fibers with a fiber length of 6 mm or more tend to aggregate because the fiber length is long, and the aggregation rate S after kneading the grout for 2 minutes may exceed 20%, and the amount of fibers having a fiber length of 6 mm or more is 0.1. If it is more than% by volume, the fluidity is lowered, which is not preferable.

As the material of the dissociable focusing fiber, polyamide fiber (trade name: aramid fiber), polyvinyl alcohol fiber (trade name: vinylon fiber), carbon fiber or the like can be used. Of these, aramid fiber is preferable because it has a high tensile strength of 350 kg / mm ² and can increase the fatigue durability of grout with a small amount.

The grout material of the present invention can contain a re-emulsified powder resin. The re-emulsified powder resin is a powdered resin that can be re-emulsified by adding a stabilizer or the like to a rubber latex or a resin emulsion, and is defined in the Japanese Industrial Standards (JIS A 6203). As the re-emulsified powder resin, for example, acrylic type, acrylic-beova type, EVA (ethylene / vinyl acetate copolymer) type, SBR (styrene / butadiene rubber) type and the like are known. An acrylic type is preferable to further enhance the fatigue durability of grout.

By containing the re-emulsified powder resin, the fatigue durability of the grout can be enhanced even if the amount of the quick-hardening material is increased. Specifically, the grout material of the present invention contains a fast-hardening material content of 8% by mass or more and 40% by mass or less, and a re-emulsified powder resin in an amount of 3.0 to 6.0% by mass in the grout material. By doing so, it is possible to maintain the fluidity of the JA funnel flow time of 30 seconds or less for the fresh grout and enhance the fatigue durability of the grout. If the content of the re-emulsified powder resin is less than 3.0% by mass, the above effect is poor, and if it exceeds 6.0% by mass, water is insufficient at the time of kneading and the fluidity is deteriorated.

In the backfill grout material of Patent Document 3, it is shown that the content of the re-emulsified powder resin is preferably 0.5 to 8% by mass of the cement, but the content of the fast-hardening material of this backfill grout material is Is limited to 1 to 6% by mass with respect to cement, and the amount of the quick-hardening material in the embodiment is 3% by mass, and the amount of the re-emulsified powder resin is 2% by mass. Therefore, it is not possible to know from Patent Document 3 the effect of using the re-emulsified powder resin in the above-mentioned content on a fast-hardened lumber of 8 to 40% by mass with respect to cement.

The grout material of the present invention can contain an inseparable agent in water. As the inseparable agent in water, MC (methyl cellulose), HPMC (hydroxypropyl methyl cellulose), HEMC (hydroxyethyl methyl cellulose), HMP polymer (modified acrylamide monomer), guar gum derivative (hydroxypropyl guar) and the like can be used.

The grout material of the present invention contains a water reducing agent. By including a predetermined amount of water reducing agent, the fluidity of the fresh grout is improved, and it becomes possible to inject it into the gap under the concrete pavement plate by natural flow. The content of the water reducing agent is preferably 0.05 to 1.0% by mass with respect to the cement. If the content of the water reducing agent is less than 0.05% by mass, the effect of the water reducing agent is poor, and if it exceeds 1.0% by mass, the fluidity of the grout becomes excessive and material separation occurs, and the fibers float on the upper surface of the grout. May come. As the water reducing agent, a commercially available polycarboxylic acid salt-based high-performance water reducing agent (trade name: Melflux, etc.) can be used.

The grout material of the present invention contains a coagulation modifier. As the coagulation adjusting agent, an inorganic carbonate, an inorganic sulfate, an oxycarboxylic acid, an oxycarboxylic acid salt and the like can be used. By containing the coagulation adjuster, an appropriate time until gelation (time until the start of coagulation) is secured to maintain good fluidity during construction, and after the above time elapses, bleeding is caused by the progress of gelation. By suppressing the generation of short fibers and increasing the viscosity of the grout, the separation of short fibers in the grout is suppressed and the dispersibility of the short fibers is improved.

The content of the coagulation adjuster is preferably 0.0 to 3.0% by mass with respect to the cement. If the content of the coagulation adjuster exceeds 3.0% by mass, the time until the start of coagulation is too long, and the short fibers are likely to be unevenly distributed on the grout surface to cause material separation.

The grout material of the present invention may contain an inorganic filler. As the inorganic filler, ordinary calcium carbonate powder for roads, fly ash, silica fume and the like can be used. Of these, ordinary calcium carbonate powder for roads, fly ash and the like are preferable, and ordinary calcium carbonate for roads and the like are particularly preferable.

The grout material of the present invention is a concrete standard specification (standard edition) (JSCE F-) in a grout mixed with a water grout material ratio (W / B) of 35 to 65% when water is added to the grout material. 531-2018 "PC grout fluidity test method (draft)" [JSCE]) has a fluidity of 30 seconds or less in the JA funnel flow test. In the following description, the JA funnel flow test is a JA funnel flow test based on the above standards by the Japan Society of Civil Engineers. If the flow time exceeds 30 seconds, the fluidity is low, and it becomes difficult to satisfactorily inject into the voids under the concrete pavement slab. If the water grout material ratio (W / B) is less than 35%, the required fluidity cannot be obtained, and the flow time of the JA funnel test generally exceeds 35 seconds. On the other hand, when the water grout material ratio (W / B) exceeds 65%, it becomes difficult to suppress bleeding.

The grout made of the grout material of the present invention is excellent in long-term strength of a material age of 7 days or more, has high powder-forming resistance to repeated loads, and is excellent in fatigue durability. Specifically, the compressive strength of a material age of 7 days or more is 20 N / mm ² or more.

The fatigue durability of grout can be evaluated from the wheel tracking test specified in the water immersion wheel tracking test method (Pavement Survey / Test Method Handbook (edited by Japan Road Association (2019))). For fatigue durability, the strain generated on the lower surface of the grout is directly measured, and the strain generated on the grout in the actual structure is calculated by three-dimensional finite element analysis, and this calculated value is used to design the concrete standard specification. (Established in 2017) It can be evaluated according to the fatigue strength formula of concrete shown in [Civil Engineering Society].

The grout material of the present invention has a high initial strength of grout while maintaining good fluidity of fresh grout by containing dissociative focused fibers. The focused fibers are less likely to agglomerate during dry mixing and are uniformly dispersed. On the other hand, if unfocused fibers are used, they tend to be lumpy during dry mixing (premix) and cannot be uniformly dispersed. Further, since the surface of the dissociative focused fibers that has been treated with oil has water repellency, the fibers are dispersed without being entangled with each other in the presence of water due to the water repellency, and are uniformly dispersed in the grout. Therefore, the fatigue durability of grout can be improved.

The grout of the present invention has a compressive strength of 2 N / mm ² or more at a material age of 2 hours. Therefore, it is suitable for use in an environment where service is required in a short time after construction. For example, in pavement repair such as an apron at an airport facility, it is necessary to be able to operate in a short time of about several hours after construction, and the grout material of the present invention can be used in such a short time.

The grout material containing the re-emulsified powder resin of the present invention enhances fatigue durability against repeated loads when the content of the quick-hardening material is increased to increase the initial strength at a material age of 2 hours.

Further, the grout material of the present invention has good fluidity, and the flow time of the grout mixed at a water grout material ratio (W / B) of 35 to 65% is 30 seconds or less in the JA funnel test. Therefore, for example, the back side of a concrete pavement slab having a size of 0.4 m × 4.5 m × a gap of 5 mm can be filled by natural flow. Further, the displacement followability with respect to the load is good.

Specifically, for example, in the above-mentioned WT test (wheel tracking test), the grout of the present invention has a crack density under a repeated load of 2000 times under the condition of using a loading plate (polycarbonate plate) having a thickness of 5 mm. It is about 0.002%, has a much smaller crack density than the conventional grout material, and has high fatigue durability against repeated loads.

Further, the grout of the present invention has a compressive strength of 20 N / mm ² or more at 7 days of age, has sufficient long-term strength, and has high fatigue durability against repeated loads. Even if it is repeatedly loaded by an aircraft or a large vehicle, it is unlikely to become powdery due to fatigue. Therefore, it can be suitably used as a backfill grout for paved slabs such as container yards of airports and port facilities where aircraft and large vehicles enter and exit.

Graph showing fracture energy test results Side view of WT test Planar explanatory view of WT test

Hereinafter, examples of the present invention will be shown together with comparative examples. Table 1 shows the materials used. Table 2 shows the blending ratio of the base grout material.

[Example 1]
Focused fiber A (surface oil treatment: oil content 2% by mass, water content 0% by mass) shown in Table 1 was added to the base grout material having the blending ratio shown in Table 2 and the fiber addition rate was 0.20 volume with respect to the grout. The grout material in the form of powder was produced by blending so as to be% and dry-mixing. After completion of the dry mixing, a powdery grout material was placed on a sieve having a mesh opening of 4 mm to recover the agglomerate G1, and the agglutination rate (S ₁ ) was determined by the above formula [1].
Next, water was added so that the ratio of the water grout material was 50%, and the mixture was kneaded for 2 minutes. After the kneading was completed, the agglomerates G2 were collected through a slurry-like grout on a sieve having a mesh opening of 4 mm, and the agglutination rate (S ₂ ) was determined by the above formula [1]. In addition, the flow time of the JA funnel test was measured. The results are shown in Table 3 (sample of the present invention).

On the other hand, as the comparative sample 1, a fibrous body (focused fiber, no surface oil treatment, water content 5%) in which aramid single fiber is moistened and integrated is used, and this is used as the base glaut material for the glaut. The fibers were blended so as to have a fiber addition rate of 0.20% by volume, and the aggregation rate (S ₁ ) after completion of the dry mixing was determined in the same manner as in the sample of the present invention. Further, water was added and the grout material was kneaded at a water grout material ratio of 50%, and the agglutination rate (S ₂ ) and the JA funnel flow time 2 minutes after the start of kneading were determined. The results are shown in Table 3 (Comparative Sample 1).
Further, as the comparative sample 2, a rose aramid single fiber was used, and this was blended with the base grout material so that the fiber addition ratio was 0.20% by volume with respect to the grout, in the same manner as the sample of the present invention. The agglomeration rate (S _{1 ) after the dry mixing, the agglomeration rate (S 2} ) 2 minutes after the start of kneading, and the JA funnel flow time were determined. The results are shown in Table 3 (Comparative Sample 2).

As shown in Table 3, in the sample of the present invention, both the agglutination rate (S ₁ ) after dry mixing and the agglutination rate (S ₂ ) after kneading are much smaller than those of comparative samples 1 and 2, and the fibers of the fiber The lumps are unlikely to occur, and the single fibers are well dispersed in the grout. Therefore, it has good fluidity, and the JA funnel flow time is 20 seconds or less.
On the other hand, Comparative Sample 1 is a focused fiber in a water-containing state, and since the surface is not oil-treated, the fibers have good hydrophilicity when they come into contact with water. Aggregate) is formed. Therefore, the agglutination rate (S ₂ ) after kneading is as high as 36%, and the JA funnel flow time also exceeds 20 seconds.
Further, when the aramid single fiber of the comparative sample 2 is used, the agglutination rate (S ₁ ) after the dry mixing and the agglutination rate (S ₂ ) after the kneading are significantly larger than those of the sample of the present invention and the comparative sample 1. Is expensive. Moreover, in the flow test, the flow path is blocked in the middle.

[Example 2]
The focused fibers A shown in Table 1 were mixed with the base grout having the blending ratio shown in Table 2 in a dry manner by blending the fiber amounts shown in Table 4 to prepare a premixed powder grout material. Water was added to this, and the grout was prepared by kneading at a water grout material ratio of 50% for 2 minutes. The fresh properties of this grout were visually observed and the following tests were conducted. These results are shown in Table 4.
Test method JA funnel flow test: JA funnel flow test specified in the concrete standard specification (standards) (JSCE F-531-2018 "PC grout fluidity test method (draft)" [JSCE]).
Compressive strength: Compliant with JSCE-G505-2018 "Compressive strength test method for mortar or cement paste using cylindrical specimen".
Tensile strength: Compliant with JIS A 1113: 2018 "Split tensile strength test method for concrete".
Bending strength: Compliant with JIS R 5201: 2015 "Physical test method for cement".
Fracture energy: Performed according to the standard (JSCE-G552 "Bending strength and bending toughness test method of steel fiber reinforced concrete"). The fracture energy is calculated based on the area surrounded by the load-deflection diagram between the break points from the start of the test. In this embodiment, the calculation was made based on the area surrounded by the load-deflection diagram up to a displacement of 5 mm.
Test Results The fresh properties of the grout were good up to a fiber content of 0.25% by volume, but when the fiber content was 0.40% by volume, there were many fiber balls and the fresh properties of the grout deteriorated. When the fiber content is 0.05% by volume to 0.25% by volume, the flow time is 20 seconds or less, the fluidity is good, and the tensile strength, bending strength, and fracture energy are improved. When the fiber content is 0.15% by volume to 0.25% by volume, the tensile strength and the bending strength are high. Therefore, the amount of the focused fiber A blended in the grout is preferably 0.05% by volume or more and less than 0.40% by volume, preferably 0.15% by volume to 0.25% by volume.

[Example 3]
The re-emulsified powder resin in the blending amount shown in Table 5 was added to the base grout material having the blending shown in Table 2. Further, the focused fiber A was added in an amount of 0.05% by volume based on the grout and kneaded at a ratio of the water grout material to 50% to prepare grout (samples A1 to A5). The JA funnel flow test was performed on these samples (A1 to A5) in accordance with the standard (JSCE-F531-2018). In addition, a compressive strength test was conducted to measure the static elastic modulus.
The compressive strength test uses a φ5 x 10 cm test piece and complies with the standard (JSCE-G505-2018: Civil Engineering Society standard "Compressive strength test method for mortar or cement paste using a columnar specimen (draft)"). , 2 hours and 7 days of compressive strength were measured.
For the static elastic modulus, a test piece of φ5 × 10 cm was used, and the static elastic modulus of 7 days of age was measured according to the standard (JIS A 1149: 2017 “Concrete static elastic modulus test method””.
The results are shown in Table 6.

As shown in Table 6, when the blending amount of the re-emulsified powder resin is in the range of 3 to 5% by mass, the kneaded state is good, and when it is 6% by mass, it is a little difficult to be compatible with water, but the flow time and the age of the material are 2 hours. The compressive strength of is good. On the other hand, when the blending amount of the re-emulsified powder resin is 7% by mass, it takes time to knead uniformly. Therefore, the content of the re-emulsified powder resin is preferably 3 to 6% by mass based on the internal division of the grout material. Further, all of the samples A2 to A4 of the present invention have a compressive strength of 4 N / mm ² or more at a material age of 2 hours, which exceeds the target strength of 2 N / mm ^2.

[Example 4]
To the base grout material of Table 2, the re-emulsified powder resin of the blending amount shown in Table 7, the focusing fiber A (3 mm) and the focusing fiber B (6 mm) are added, and the mixture is kneaded with the water grout material ratio shown in Table 7 to grout. (Samples B1 to B6) were prepared. The JA funnel flow test was performed on these samples (B1 to B6) in accordance with the standard (JSCE-F531-2018). Furthermore, a filling property test and a fracture energy test were performed.
In the filling property test, a test device having a width of 400 mm, a length of 4500 mm, and a gap of 5 mm was filled with grout under a natural flow having a head difference of 1000 mm, and the time required for the grout to reach the tip from the start of filling was measured. In the destructive energy test, a test piece of 20 × 100 × 400 mm was used, and the destructive energy was measured by a universal testing machine.
The results of the JA funnel flow test and the filling property test are shown in Table 7. The results of the destructive energy test are shown in FIG.

As shown in Table 7, in the grout material containing the re-emulsified powder resin, the sample B3 containing 0.25% by volume of the focused fiber A (3 mm) had a funnel flow time of 25 seconds and had good fluidity. It is shown and the filling time is short. On the other hand, the funnel of the flow test was blocked in the sample B4 containing 0.15% by volume of the focusing fiber B (6mm), and the sample B5 containing 0.1% by volume of the focusing fiber B (6mm) could not be injected during the filling property test. become. On the other hand, as shown in sample B6, when the total amount of fibers is 0.1% by volume and the content of the focused fibers B (6 mm) is 0.05% by volume, an appropriate fluidity is exhibited and it is natural. It can be filled in the flow. Therefore, the total content of the focused fibers is preferably 0.05 to 0.25% by volume, and the amount of fibers having a fiber length of 6 mm or more is preferably less than 0.1% by volume.

Further, as shown in the graph of FIG. 1, by including the focusing fiber A, the displacement with respect to the load is large and the displacement followability is high (Sample B2). Further, by including the re-emulsified powder resin, the displacement (displacement followability) with respect to the load becomes larger and better (Sample B3).

[Example 5]
Wheel tracking tests were performed on the samples B1, B2, and B3 in Table 7.
The wheel tracking test (WT test) was conducted in accordance with the flooded wheel tracking test method (Pavement Survey / Test Method Handbook (edited by Japan Road Association (June 2007))). The test conditions are shown in Table 8. The outline of the test method is shown in FIGS. 2 and 3. As shown in the figure, a test body (backfill grout) 11 is placed on the upper surface of the simulated roadbed material (Styrofoam) 10 and pressed by a restraint plate 12, and a load plate (polycarbonate plate: thickness 5 mm) 13 is installed on the upper surface. The traveling wheel 14 was pressed from the upper side of the loading plate 13, and the traveling times shown in Table 8 were reciprocated to measure the number of times the grout was damaged. Table 9 shows the test conditions for the WT test.

Sample B1 was destroyed in 1500 WT tests, so the test was discontinued. No destruction was observed in the fibers-rich samples B2 and B3 even in 2000 WT tests. In the state of the plate after 2000 times of the WT test, the crack density of the sample B2 is 0.009%, whereas the crack density of the sample B3 is 0.002%, and the sample B3 of the present invention is in the WT test. It was shown that the resistance to fatigue durability was remarkably high. It is considered that the result of 2000 times in the test of the loaded plate 5 mm corresponds to the result of about 20,000 times in the test of the loaded plate 10 mm of Patent Document 3.

10-Simulated roadbed material (Styrofoam), 11-Test specimen (Backfill grout),
12-Restriction plate 12, 13-Loading version (polycarbonate version), 14-Running wheel

Claims (11)

A backfill grout material for concrete pavement slabs containing cement as the main component, fast-hardening material, fiber, water reducing agent, and coagulation adjuster. A highly durable backfill grout material characterized by being a dissociative focused fiber that defibrates into fibers. The highly durable back according to claim 1, wherein the fiber is a dissociative focused fiber having an agglutination rate of 20% or less 2 minutes after the start of kneading when the grout material and water are kneaded to form a grout. Filled grout material. The highly durable backfill grout material according to claim 1 or 2, wherein the content of the dissociative focused fibers is 0.05% by volume or more and less than 0.40% by volume with respect to the grout. The content of the dissociative focused fibers is 0.05% by volume or more and less than 0.40% by volume with respect to the grout, and the content of the focused fibers having a fiber length of 6 mm or more is less than 0.1% by volume. The highly durable backfill grout material according to any one of claims 1 to 3. The highly durable backfill grout material according to any one of claims 1 to 4, wherein the dissociative focusing fiber is an aramid fiber. The highly durable backfill grout material according to any one of claims 1 to 5, wherein the content of the fast-hardening material is 8% by mass or more and 40% by mass or less with respect to the cement. Any of claims 1 to 6, which contains a re-emulsified powder resin and the content of the re-emulsified powder resin is 3.0% by mass or more and 6.0% by mass or less in the internal division of the backfill grout material. Highly durable backfill grout material described in. The highly durable backfill grout material according to claim 7, wherein the re-emulsified powder resin is an acrylic re-emulsified powder resin. The content of the water reducing agent is 0.05% by mass or more to 1.0% by mass or less with respect to the cement, and the content of the coagulation adjusting agent is 0.00 to 3.0% by mass or less with respect to the cement. The highly durable backfill grout material according to any one of claims 1 to 8. The flow time of the JA grouting flow test of the grout obtained by kneading the above grout material at a water grout material ratio (W / B) of 35 to 65% is 30 seconds or less, and the grout material age is compressed by 2 hours after hydration hardening. The highly durable backfill grout material according to any one of claims 1 to 9, wherein the strength is 2 N / mm ^{2 or less.} A highly durable backfill grout having ^{a compressive strength of 20 N / mm 2} or more formed by the backfill grout according to any one of claims 1 to 10 and having a material age of 7 days.

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