JP2019210170A - Spraying material - Google Patents

Abstract

To provide a spraying material with extra high strength which is pumpable and sprayable, and can be applied by spraying method.SOLUTION: A spraying material of this invention containing at least moderate heat cement, blast furnace slag powder, and silica fume as powder, and further contains a high-performance water reducing agent, aggregate, quick setting agent, and water. The compressive strength after 28 days after spraying is 70 N/mmor more. In the spraying material composition of this invention, the water powder ratio (W/P) is preferably, 15% or more and 25% or less, and more preferably, the base concrete in which the quick-setting material has been removed, or the base mortar has a plastic viscosity of 5 Pa s or more and 25 Pa s or less, and a yield value of 0.01 Pa or more and 15 Pa or less.SELECTED DRAWING: None

Description

  The present invention relates to an extremely high strength spray material.

  In a mountain tunnel method such as NATM, it is common to prevent collapse of a natural mountain by spraying sprayed concrete onto the natural ground surface exposed by excavation. The shotcrete mixes the concrete pumped by the concrete pump with the rapid setting agent and sprays it on the ground surface.

Most of conventional conventional shotcrete has a compressive strength of about 18 N / mm ^{2 at} the age of 28 days, and what is called high strength shotcrete is the compressive strength at the age of 28 days. Some sprayed concrete showing about 40 N / mm ² was found (Patent Document 1).

  When constructing a mountain tunnel construction method in a mountain where a crush zone appears under conditions of high earth covering and high earth pressure, higher strength shotcrete is required to ensure safety and reduce costs. . However, conventional ultra-high-strength concrete has high viscosity due to the high amount of powder, so that the workability such as pumpability and sprayability is not sufficient, and spraying can be performed. Can not.

JP 2001-302322 A

  It is an object of the present invention to provide a spraying material that has a pumpability and sprayability and is capable of being sprayed while being ultra-high strength.

Means for solving the problems of the present invention are as follows.
1. Containing at least medium heat cement, blast furnace slag powder, and silica fume as powder,
In addition, it contains high-performance water reducing agent, aggregate, quick setting agent, water,
A spray material having a compressive strength of 70 N / mm ² or more when 28 days have elapsed after spraying.
2. The water powder ratio (W / P) is 15% or more and 25% or less. Spray material as described in.
3. 1. The base concrete or base mortar excluding the rapid setting agent has a plastic viscosity of 5 Pa · s to 25 Pa · s, and a yield value of 0.01 Pa to 15 Pa. Or 2. Spray material as described in.
4). The quick setting agent is liquid. ~ 3. The spraying material in any one of.
5. Containing at least medium heat cement, blast furnace slag powder, and silica fume as powder,
A powdery composition for a spraying material, wherein the compressive strength is 28 N / mm ² or more after 28 days from spraying.

The spray material of the present invention has a very high compressive strength of 70 N / mm ² or more when 28 days have elapsed after spraying. Therefore, the spray material of the present invention can be suitably used in a site where the ground pressure is high. The spray material of the present invention is excellent in pumpability and sprayability even though it has an ultra-high strength, and can be sprayed. The spray material of the present invention using a liquid quick-setting agent can realize strength development and a low rebound rate.

The spray material of the present invention contains at least moderately heated cement, blast furnace slag powder, and silica fume as powder, and further includes a high-performance water reducing agent, an aggregate, a quick setting agent, and water. The compression strength (hereinafter referred to as spray compression strength) after 28 days is 70 N / mm ² or more.

With the above configuration, the flowability, viscosity, or rheological properties such as the yield value or plastic viscosity of the spray material can be within the required range, and the required pumpability and sprayability of the spray material of the present invention can be achieved. And an ultra-high strength spray material can be obtained. In the present invention, ultra-high strength means that the compressive strength of the spray material during spraying is at least 70 N / mm ² or more. The spray material of the present invention preferably has a spray compressive strength of 80 N / mm ² or more, more preferably 90 N / mm ² or more, and most preferably 100 N / mm ² or more.

The spray material of the present invention contains at least moderately heated cement, blast furnace slag powder, and silica fume as powders. As long as the spray material of the present invention satisfies a spray compression strength of 70 N / mm ² or more, Portland cement, slag, limestone powder, alumina powder, silica sol, carbide powder, nitride powder, quartz powder, fly ash, etc. It can be included as a powder.

  The spray material of the present invention maintains its deformability when an external force is applied, such as during kneading or pumping, and conversely, when sprayed, it deforms even when a collision force against the spray surface is applied. Therefore, the conflicting characteristics of suppressing rebound are required. From the rheological point of view, it is desirable to have pseudoplasticity or thixotropy (at least the state in which the dilatant behavior is suppressed) at the time of kneading and pumping. Is required. According to the present invention, it is possible to obtain an ultra-high-strength spray material that has the required flow characteristics and rheological characteristics as described above, and has good spray performance that was not obtained with conventional spray concrete.

"Medium heat cement"
Medium-heated cement is a medium-heated Portland cement specified in JIS R5210, and has a lower heat of hydration than ordinary Portland cement. The spray material of the present invention is characterized by using medium-heated Portland cement, and the mechanism is unknown, but the spray material blended with medium-heat Portland cement is compared with the spray material blended with ordinary Portland cement. And it is excellent in pumpability and sprayability.
In the spray material of the present invention, the blending amount of moderately hot Portland cement in the powder is not particularly limited as long as the spray compressive strength of 70 N / mm ² or more is satisfied, but it is preferably 40% by weight or more.

"High-strength admixture containing blast furnace slag powder"
Blast furnace slag powder is obtained as a by-product when iron metal is produced from iron ore using a blast furnace, and has a performance similar to that of cement, such as having latent hydraulic properties. Widely used in the civil engineering and construction fields as a raw material and a component of cement admixtures. The high-strength admixture containing blast furnace slag used here is based on silica fume and blast furnace slag gypsum based admixture. By replacing a part of the binder, high-strength concrete of 70 N / mm ² or more can be manufactured.
In the spray material of the present invention, the blending amount of the high-strength admixture containing the blast furnace slag powder in the powder is not particularly limited as long as the spray compressive strength of 70 N / mm ² or more is satisfied. Preferably there is.

  As the blast furnace slag powder used in the present invention, those available as cement admixtures can be used without particular limitation. However, when the spray material of the present invention requires ultra-high strength characteristics, dilatancy phenomenon occurs in fresh mortar and fresh concrete with a low water-powder ratio blended with blast furnace slag powder, and these are difficult to mix. Become. In order to suppress the dilatancy phenomenon, it is preferable to use blast furnace slag powder containing 1 wt% or more and 10 wt% or less of particles of 90 μm or more that do not pass through a sieve having a nominal opening of 90 μm defined in JIS Z8801-1. The dilatancy phenomenon means that when a sudden external force is applied to a fluid-semi-fluid system consisting of powder and water to cause deformation, water near the surface is sucked into the internal particle gap. This is a phenomenon that becomes hard and temporarily in a solid state, but returns to its original state when the external force is no longer applied and left to stand.

By using a blast furnace slag powder in which particles of 90 μm or more are 1% to 10%, a high strength admixture containing the blast furnace slag powder having a broad particle size distribution can be obtained. If the particles of 90 μm or less of the blast furnace slag powder are less than 1.0%, it becomes difficult to suppress the occurrence of the dilatancy phenomenon, and breathing is likely to occur. Moreover, since the ratio of a coarse blast furnace slag powder will increase when the particle | grains of 90 micrometers or more exceed 10%, intensity | strength expression property worsens.
Furthermore, although there are substantially no particles of 90 μm or more in a general binder, blast furnace slag powder containing particles of 90 μm or more is due to the presence of particles of 90 μm or more between the binder and the fine aggregate. Since the powder filling property is improved, mortar and concrete having low viscosity can be obtained.

  When fresh mortar or fresh concrete is produced using an ultra-high strength admixture containing blast furnace slag powder having a broad particle size distribution by mixing powders with different particle size distributions, the plastic viscosity and yield value are reduced, and the water powder Even with a low water composition having a ratio (W / P) of 20% or less, the dilatancy phenomenon is less likely to occur and mixing is facilitated. In addition, the cured concrete also has ultra-high strength due to its low water composition.

"Silica fume"
Silica fume is spherical ultrafine particles obtained by collecting dust in exhaust gas generated when silicon metal, ferrosilicon, silicon alloy, zirconium, etc. are produced. Silica fume can be used without particular limitation as a cement admixture, and is not limited in terms of quality such as particle size and BET specific surface area.
Silica fume is a spherical ultrafine particle, and therefore, when a high-performance water reducing agent is used in combination, it imparts good fluidity to the cement kneaded material. And the spray material of this invention has the outstanding pumpability and sprayability by including a silica fume.
In the spray material of the present invention, the blending amount of silica fume in the powder is not particularly limited as long as the spray compression strength of 70 N / mm ² or more is satisfied, but it is preferably 5% by weight or more.

"High performance water reducing agent"
The high-performance water reducing agent is defined in JIS A6204. As high performance water reducing agents, polycarboxylic acid ether compounds, naphthalene sulfonic acid compounds, melamine sulfonic acid compounds, amino sulfonic acid compounds, alkylallyl sulfonic acid compounds and derivatives or modified products thereof, polyether derivatives, Polyglycol derivatives, ester compounds, and those containing a mixture thereof as the main component can be used.
In the present invention, since the water powder ratio (W / P) is extremely low, a high-performance water reducing agent recommended by the manufacturer for ultra-high-strength concrete is preferable, and those containing a polycarboxylic acid ether compound are particularly preferable. For example, “Master Grenium SP8HU” manufactured by BASF Japan Co., Ltd., “Mighty 3000TH” manufactured by Kao Co., Ltd., “Tupole SSP-104” manufactured by Takemoto Yushi Co., Ltd. “Floric SF500U” manufactured by Floric Co., Ltd., Nippon Seika Co., Ltd. “SEICAMENT 1200NT” manufactured by the company is exemplified.
The high-performance water reducing agent may be used in a recommended blending amount, but is usually 1 part by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the powder. In addition, an antifoaming agent can be used in combination with a high-performance water reducing agent in order to defoam the air entrained during kneading.

"aggregate"
In the spray material of the present invention, the aggregate is not particularly limited, and a conventionally known aggregate can be used. For example, the fine aggregates include river sand, sea sand, mountain sand, quartz sand, crushed sand, limestone sand, recycled aggregate sand, calcined bauxite ground sand, iron ore ground sand, and quartz porphyry. There may be mentioned crushed sand, slag-based fine aggregate, or mixtures thereof. As the coarse aggregate, river gravel, land gravel, crushed stone, slag coarse aggregate, or a mixture thereof can be used. In the spray material of the present invention, as the aggregate, only a fine aggregate can be used, or a fine aggregate and a coarse aggregate can be used in combination. The blending ratio of fine aggregate and coarse aggregate in the aggregate and the blending amount of the aggregate with respect to the powder can be selected as appropriate according to the application in which the spray material is used.

"Admixture"
In the spray material of the present invention, the admixture is not particularly limited, and conventionally known materials can be used. For example, limestone fine powder, quartz fine powder, meteorite fine powder, rock fine powder, gypsum and the like can be mentioned.

"Quick setting agent"
The spray material of the present invention includes a quick setting agent. By including the quick setting agent, the viscosity of the spray material increases, and the amount that flows down after spraying decreases. As the quick setting agent, calcium aluminate-based, calcium sulfoaluminate-based, aluminate-based powders, aluminate-based, water-soluble aluminum salt-based liquids, etc. are used without particular limitation. be able to. Among these, liquid quick setting agents are preferable because of the development of strength and the reduction of the rebound rate. Specifically, the rebound rate can be reduced to 10% or less by using a liquid quick setting agent.

"Other ingredients"
The spraying material which concerns on this invention can contain other components other than the said powder, a high performance water reducing agent, and an aggregate. Examples of other components include so-called admixtures, fibers such as metal fibers and / or organic fibers.

  The admixture is an additive used for many purposes such as improvement of fluidity and strength development, setting control, and improvement of durability, and at least one kind can be used. As this admixture, a high-performance AE water reducing agent, a fluidizing agent, an antifoaming agent, a setting accelerator, a setting retarding agent, a thickener, a shrinkage reducing agent, a foaming agent, a rust preventive agent, etc. can be used alone. It can be used in multiple combinations.

  Examples of the fibers include metal fibers, organic fibers, inorganic fibers, or composite (hybrid) fibers obtained by mixing metal fibers with organic fibers or inorganic fibers. Examples of metal fibers that can be mixed include steel fibers, high-tensile steel fibers, stainless steel fibers, and titanium fibers. Organic fibers include polypropylene (PP) fiber, polyvinyl alcohol (PVA) fiber, aramid fiber, polyethylene fiber, ultra-high strength polyethylene fiber, polyethylene terephthalate (PET) fiber, rayon fiber, nylon fiber, and polyvinyl chloride fiber. Polyester fiber, acrylic fiber, alkali-resistant glass fiber, etc. can be used. As the inorganic fiber, carbon fiber, basalt fiber obtained by melting and spinning natural basalt, glass fiber, silica fiber, and the like can be used.

  The spray material of the present invention can be made into a cement-based material (concrete, mortar, or cement paste) by mixing and kneading water in addition to the above components. At this time, the water powder ratio (W / P), which is a mass percentage of water and powder, is preferably 15.0% or more and 25.0% or less from the viewpoint of pumpability and sprayability. Further, since the spray compression strength can be increased when the water powder ratio is small, the water powder ratio is more preferably 20.0% or less, and further preferably 18.0% or less. Preferably, it is most preferably 16.5% or less.

  The spray material of the present invention has a low plastic viscosity and yield value as compared with the conventional Portland cement-based spray material by including the above-described components. Here, the plastic viscosity is a viscosity after starting the flow, and if the plastic viscosity is low, the inside of the hose or the like can be transported with a small pressure. The yield value is a stress value at the start of flow. When the yield value is low, the yield value can be sucked with a small pressure. The spray material of the present invention preferably has a mortar (matrix) plastic viscosity of 25 Pa · s or less. The spray material of the present invention preferably has a mortar (matrix) yield value of 15 Pa or less. On the other hand, at the time of spraying, if the plastic viscosity and yield value are too low, problems of rebound and sag are likely to occur. Therefore, the plastic viscosity is preferably 5 Pa · s or more, and the yield value is preferably 0.01 Pa or more. . In the present invention, the plastic viscosity and yield value mean the plastic viscosity and yield value of so-called base mortar or base concrete excluding the rapid setting agent, unless otherwise specified.

  The spraying material of the present invention can be subjected to construction such as kneading and spraying using commonly used equipment.

"material"
The materials shown in Table 1 below were used.

"Test method"
Compressive strength test method and specimen manufacturing method 1) Compressive strength test method and specimen manufacturing method The specimen for the compressive strength test has a diameter of 50 mm according to JIS A1132: 2014 “How to make a specimen for concrete strength test”. It was manufactured with a height of 100 mm.
The compressive strength test was performed according to JIS A1108: 2006 “Concrete compressive strength test method”. The curing was a sealed curing under a 20 ° C environment.
2) Test method for compressive strength of shotcrete and specimen preparation method The test specimen for test of compressive strength of shotcrete is JSCE-F 561-2005 “Test specimen for test of compressive strength of shotcrete (mortar). In accordance with “How to Make (Draft)”, it was manufactured with a diameter of 100 mm and a height of 200 mm.
The compressive strength test was measured in accordance with JIS A1107: 2012 “Method for collecting core from concrete and compression test method”. The curing was a sealed curing under a 20 ° C environment.

・ Measurement method of plastic viscosity and yield value Plastic viscosity and yield value are as follows: “Watanabe, Hashimoto, Takeda: Examination on evaluation of fluidity in pipe of ultra high strength mortar, Proceedings of Annual Conference of Japan Society of Civil Engineers, V-135, pp , 269-270, 2017, 17.9 ".

・ Flow (mortar flow, concrete flow)
(1) Measuring method of mortar flow In accordance with JIS R5201: 2015 “Physical testing method of cement 12. Flow test”, the measurement was performed without applying vibration.
(2) Measuring method of concrete flow It measured according to JIS A 1150: 2007 "slump flow test of concrete".

-Measuring method of air quantity The air quantity was measured according to JIS A1128: 2005 "Test method by pressure of air quantity of fresh concrete-air chamber pressure method".
-Measuring method of rebound rate It measured according to JSCE-F 563-2005 "Rebound rate test method (draft) of shotcrete (mortar)".

“Experiment 1”
Each material was kneaded with the blending ratio shown in Table 2 to prepare a mortar, and each test was performed. The test results are shown in Table 3 below.

Compared with the mixing | blending 1-3 which uses normal Portland cement, the yield value and the plastic viscosity of the mixing | blendings 4-6 using a moderately-heated cement fell remarkably.
When the blending amount of the blast furnace slag powder was increased, the plastic viscosity tended to decrease for both ordinary Portland cement and moderately heated cement. Yield values tended to decrease for normal Portland cement and to increase for medium heat cement.

"Experiment 2"
Based on Formulation 5, which was excellent in the balance of strength, plastic viscosity, and yield value in Experiment 1, the water / powder ratio (W / P) was changed to concrete, and each test was performed. The formulation and results are shown in Tables 4 and 5 below.

  The concrete containing the coarse aggregate had a viscosity higher than that of the mortar, and the viscosity was further increased when the water / powder ratio was decreased. In addition, since the increase in viscosity was obvious in the formulations 7 to 9, the yield value and the plastic viscosity were not measured. In particular, since the formulation 9 was confirmed to be very high in visual observation, various measurements were performed. not going.

“Experiment 3”
Returning to Formulation 5, which was excellent in balance of strength, plastic viscosity, and yield value in Experiment 1, the mortar was prepared by adding silica fume, and each test was performed. The formulations and results are shown in Tables 6 and 7 below.

  Compared with the blend 5 containing 20% by weight of the blast furnace slag powder in the powder, the blend 10 in which half of the blast furnace slag powder was replaced with silica fume had a slightly increased yield value but a reduced plastic viscosity. Further, as shown in Formulation 11, by including silica fume, the yield value and the plastic viscosity could be kept low even if the water powder ratio was reduced. Moreover, although the mixing | blending 12 was high-viscosity, coexistence of a rheological characteristic and intensity | strength can be expected by increasing water.

“Experiment 4”
Coarse aggregate was blended with blend 11 to make concrete, and each test was performed. The formulation and results are shown in Tables 8 and 9 below.

It was suggested that the blend 13 was sufficiently low in yield value and plastic viscosity even as concrete.
From the knowledge so far, the hardened material sprayed with concrete has a compressive strength reduced to about 70 to 80% as compared with the case where it is hardened by a normal method. Compound 13 had excellent compressive strength after 28 days of 138 N / mm ² and was expected to maintain high compressive strength even when sprayed.

"Experiment 5"
A spray material was prepared based on the formulation 13 and the formulation shown in Table 10 below, and each test was performed. The formulation and results are shown in Tables 10 and 11 below.

The spray material of the present invention was able to be sprayed with excellent pumpability and sprayability because of its low yield value and low plastic viscosity even as a small concrete having a water powder ratio of 17 to 19. Moreover, spray compression strength was as high as 94-95 N / mm < ² >, and was super high strength. Furthermore, the rebound rate of the formulation 14 is as low as 4.0%, and the rebound rate is not measured for the formulations 15 and 16, but it is predicted from the visual observation at the time of spraying that the rebound rate is equivalent. The

Claims (5)

Containing at least medium heat cement, blast furnace slag powder, and silica fume as powder,
In addition, it contains high-performance water reducing agent, aggregate, quick setting agent, water,
A spray material having a compressive strength of 70 N / mm ² or more when 28 days have elapsed after spraying.   The spray material according to claim 1, wherein the water powder ratio (W / P) is 15% or more and 25% or less.   The spraying according to claim 1 or 2, wherein the plastic viscosity of the base concrete or base mortar excluding the rapid setting agent is 5 Pa · s to 25 Pa · s, and the yield value is 0.01 Pa to 15 Pa. material.   The spray material according to any one of claims 1 to 3, wherein the quick setting agent is liquid. Containing at least medium heat cement, blast furnace slag powder, and silica fume as powder,
A powdery composition for a spraying material, wherein the compressive strength is 28 N / mm ² or more after 28 days from spraying.