Grout composition and grout

Abstract

To provide a grout composition and a grout which enable materials and water to be readily integrated, exhibit superior workability, have superior flowability as evaluated by flow and J14 funnel flow time, and demonstrate high compressive strength.SOLUTION: A grout composition comprises cement, siliceous fine powder, fine aggregate, and a water-reducing agent. The siliceous fine powder has a SiO2 content of 96 mass% or more, a BET specific surface area of 5 to 16 m2 / g, and an ignition loss of 1.0 mass% or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a grout composition and grout.

Background Art

[0002] In the construction or repair of civil engineering and building structures, or the installation of machinery, etc., a highly fluid cement-based grout material is used. In recent years, the quality of concrete used in civil engineering and building structures has been improved to be of high performance and high strength, and high strength development performance has also been required for the grout materials used.

[0003] As a method for producing high-strength mortar and concrete, a method using silica fume containing 90% or more of SiO2 as an admixture and having a water-binder ratio of 25% or less is known (Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since silica fume is ultrafine particles, it is likely to aggregate and has a problem of poor dispersibility in mortar and concrete. Especially when the water-binder ratio of mortar and concrete is small, the water affinity is poor (it takes time until the water and the material are integrated when kneading with water), and the fluidity is reduced. When the addition amount of the water reducing agent is increased to improve the fluidity, although the spread in the lateral direction is improved, it may not contribute so much to the improvement of the J14 funnel flow-down time, which is carried out as an evaluation of the fluidity of the grout material.

[0006] Accordingly, an object of the present invention is to provide a grout composition and a grout that are excellent in workability with easy integration of materials and water, excellent in fluidity evaluated by flow and J14 funnel flow-down time, and exhibit high compressive strength.

Means for Solving the Problems

[0007] As a result of intensive studies by the present inventors on the above problems, it has been found that by using a siliceous fine powder having a high SiO2 content, a small loss on ignition, and a specific BET specific surface area, a grout composition and a grout excellent in workability and fluidity and exhibiting high compressive strength can be obtained.

[0008] That is, the present invention is as follows. [1] A grout composition containing cement, siliceous fine powder, fine aggregate, and a water reducing agent, wherein in the siliceous fine powder, the SiO2 content is 96% by mass or more, the BET method specific surface area is 5 to 16 m 2 / g, and the loss on ignition is 1.0% by mass or less. [2] The grout composition according to [1], further containing a foaming agent. [3] The grout composition according to [1] or [2], wherein the content of the siliceous fine powder is 10 to 50 parts by mass with respect to 100 parts by mass of cement. [4] A grout containing the grout composition according to [1] or [2] and water, wherein the water content is 30 to 70 parts by mass with respect to 100 parts by mass of cement. [4] The grout according to [4], wherein the flow-down time of the J14 funnel measured in an environment at 20°C according to the Japan Society of Civil Engineers Standard JSCE-F 541-2013 "Test Method for Fluidity of Filling Mortar" is 6 to 10 seconds.

Effects of the Invention

[0009] According to the present invention, it is possible to provide a grout composition and a grout that are excellent in workability with easy integration of materials and water, excellent in fluidity evaluated by flow and J14 funnel flow-down time, and exhibit high compressive strength.

Modes for Carrying Out the Invention

[0010] Hereinafter, an embodiment of the present invention will be described in detail. Regarding the description of the content in this specification, it is in terms of solid content conversion and anhydride conversion. For those containing liquids, the water contained therein is included in the water content.

[0011] The grout composition of this embodiment contains cement, silica fine powder, fine aggregate, and a water reducing agent.

[0012] Various cements can be used. For example, various Portland cements such as ordinary, early strength, ultra-early strength, low heat, and medium heat; blended cements containing blast furnace slag, fly ash, or silica fume; eco-cement; rapid hardening cement, etc. can be mentioned. As the cement, ordinary Portland cement or early strength Portland cement is preferable from the viewpoint of being easily compatible with both strength development and fluidity improvement. The cement may be used alone or in combination of two or more.

[0013] The silica fine powder is a material mainly composed of SiO2, and examples include those obtained as by-products when producing ferrosilicon or metallic silicon, those of zirconia origin obtained as by-products when producing fused zirconia, those synthesized from silicon or silicon dioxide, etc. The silica fine powder according to this embodiment has an SiO2 content of 96% by mass or more, a BET specific surface area of 5 to 16 m 2 / g, and a loss on ignition of 1.0% by mass or less.

[0014] The SiO2 content of the silica fine powder is 96% by mass or more. If the SiO2 content of the silica fine powder is outside the above range, impurities increase and fluidity decreases. The SiO2 content of the silica fine powder is preferably 97% by mass or more, more preferably 98% by mass or more, and still more preferably 99% by mass or more. The SiO2 content of the silica fine powder may be less than 100% by mass. If the SiO2 content of the silica fine powder is within the above range, the material and water are more likely to be compatible, and the fluidity tends to be excellent. The SiO₂ content of the silica fine powder can be measured by a fluorescent X-ray analyzer.

[0015] The BET specific surface area of the silica fine powder is 5 to 16 m 2 / g. When the BET specific surface area of the silica fine powder is less than 5 m 2 / g, material separation is likely to occur. When it exceeds 16 m 2 / g, the wettability when adding water and kneading is poor, and a material with good fluidity cannot be obtained. From the viewpoint of better wettability and easier obtaining of good fluidity, the BET specific surface area of the silica fine powder is preferably 7 to 15.5 m 2 / g, more preferably 8 to 15 m 2 / g, and even more preferably 10 to 14.8 m 2 / g. The BET specific surface area can be measured by the nitrogen adsorption method or the like.

[0016] The loss on ignition of the silica fine powder is 1.0 mass% or less. When the loss on ignition exceeds 1.0 mass%, the amount of water reducing agent adsorbed by unburned carbon increases, resulting in a decrease in fluidity. From the viewpoint of easily obtaining good fluidity and further improving the finish during hardening, the loss on ignition of the silica fine powder is preferably 0.8 mass% or less, more preferably 0.6 mass% or less, and even more preferably 0.4 mass% or less. The loss on ignition can be measured by heating strongly in an electric furnace adjusted to 1000 °C for 15 minutes according to JIS A 6207:2016 "Silica Fume for Concrete" and based on the weight change before and after strong heating.

[0017] The pH of the silica fine powder is preferably 2 to 6, more preferably 2 to 5.5, and even more preferably 2 to 5. If the pH of the silica fine powder is within the above range, the dispersibility of the silica fine powder is good, and the wettability when adding water and kneading is likely to be improved. The pH of the silica fine powder can be measured using a 50% by mass slurry obtained by stirring water and the silica fine powder in an environment of 20°C.

[0018] The content of the silica fine powder is preferably 10 to 50 parts by mass, more preferably 12 to 40 parts by mass, still more preferably 15 to 30 parts by mass, and particularly preferably 17 to 25 parts by mass with respect to 100 parts by mass of cement. If the content of the silica fine powder is within the above range, water affinity, material separation resistance, and fluidity are further improved, and the compressive strength also tends to be high.

[0019] Examples of the fine aggregate include river sand, silica sand, crushed sand, gypsum stone, limestone sand, slag aggregate, etc. As the fine aggregate, it is preferable to use silica sand, limestone sand, etc. whose particle size is adjusted to a particle size that does not contain fine powder or coarse aggregate from among these. The fine aggregate may be used alone or in combination of two or more. The fine aggregate is preferably one having a particle size of 5 mm or less (the fraction passing through a 5 mm sieve) which is usually used.

[0020] The particle size of the fine aggregate is not particularly limited and can be adjusted within the range of the required particle size of the fine aggregate. The particle size of the fine aggregate can be considered from the coarse grain ratio defined by JIS A 1102:2014 "Test method for sieving of aggregates". From the viewpoint that better fluidity is easily obtained and bleeding is easily suppressed when made into grout, the coarse grain ratio of the fine aggregate is preferably 1 to 4, more preferably 1.5 to 3.8, and still more preferably 2 to 3.8.

[0021] The content of the fine aggregate is preferably 50 to 300 parts by mass, more preferably 80 to 280 parts by mass, still more preferably 100 to 270 parts by mass, and particularly preferably 120 to 220 parts by mass with respect to 100 parts by mass of cement. If the content of the fine aggregate is within the above range, the fluidity will be further improved.

[0022] The water reducing agent includes high-performance water reducing agents, high-performance AE water reducing agents, AE water reducing agents, and fluidizing agents. Examples of such water reducing agents include those specified in JIS A 6204:2011 "Chemical admixtures for concrete". Examples of water reducing agents include polycarboxylic acid-based water reducing agents, naphthalene sulfonic acid-based water reducing agents, lignin sulfonic acid-based water reducing agents, and melamine-based water reducing agents. Among these, lignin sulfonic acid-based water reducing agents and naphthalene sulfonic acid-based water reducing agents are preferred. The water reducing agent may be used alone or in combination of two or more kinds.

[0023] The content of the water reducing agent is preferably 0.5 to 3.0 parts by mass in terms of solid content with respect to 100 parts by mass of cement, more preferably 0.8 to 2.5 parts by mass, and even more preferably 1.0 to 2.0 parts by mass. If the content of the water reducing agent is within the above range, it is likely to have excellent resistance to material segregation and fluidity.

[0024] The grout composition of this embodiment may contain a foaming agent. Examples of the foaming agent include powders of amphoteric metals such as aluminum and zinc, and peroxide substances. The foaming agent may be used alone or in combination of two or more kinds.

[0025] The content of the foaming agent is preferably 0.0005 to 0.007 parts by mass with respect to 100 parts by mass of cement, more preferably 0.001 to 0.005 parts by mass, and even more preferably 0.0015 to 0.003 parts by mass. If the content of the foaming agent is within the above range, it is easy to prevent the settlement reduction after filling and less likely to cause a strength reduction due to excessive expansion.

[0026] In the grout composition of this embodiment, various admixtures (materials) may be blended as long as the effects of the present invention are not impaired. Examples of the admixtures (materials) include expansion materials, defoaming agents, gypsum, mirabilite, cement polymers, waterproof agents, rust preventives, shrinkage reducing agents, water retention agents, pigments, water repellents, efflorescence preventives, fibers, blast furnace slag fine powder, stone powder, clay mineral powder, slag powder, fly ash, inorganic fillers, pozzolan, etc.

[0027] The method for manufacturing the grout composition of the present embodiment is not particularly limited. For example, it can be manufactured by mixing with a gravity mixer such as a V-type mixer or a tilting concrete mixer, or a mixer such as a Henschel mixer, an injection mixer, a ribbon mixer, or a paddle mixer.

[0028] The grout composition of the present embodiment can be prepared as grout by mixing with water, and the water content can be appropriately adjusted according to the application. The water content is preferably 30 to 70 parts by mass, more preferably 32 to 60 parts by mass, and still more preferably 35 to 50 parts by mass with respect to 100 parts by mass of cement. If the water content is within the above range, it is easier to ensure fluidity and suppress the occurrence of material separation and the decrease in strength development.

[0029] For the preparation of the grout of the present embodiment, the same kneading equipment as that for ordinary grout compositions can be used, and it is not particularly limited. Examples of the kneading equipment include a mortar mixer, a grout mixer, a hand mixer, a tilting drum mixer, a twin-shaft mixer, etc.

[0030] For the grout of the present embodiment, the flow-down time of the J14 funnel measured at 20°C in accordance with the Japan Society of Civil Engineers standard JSCE-F 541-2013 "Test Method for Fluidity of Filling Mortar" is preferably 6 to 10 seconds, more preferably 6 to 9 seconds, and still more preferably 6 to 8.5 seconds. If the flow-down time of the J14 funnel of the grout is within the above range, the workability and filling property of the grout will be further improved.

[0031] The grout composition and grout of the present embodiment are such that the material and water are easily integrated, have excellent fluidity, and exhibit high compressive strength. Therefore, the grout composition and grout of the present embodiment can be suitably used for the construction or repair of civil engineering and building structures, filling of gaps, etc.

Examples

[0032] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. All examples were conducted under an environment of 20°C.

[0033] [Materials] Cement: Ordinary Portland cement Siliceous fine powders A to G: Commercially available products. Each property is shown in Table 1. Fine aggregate: Silica sand Water reducing agent: Naphthalene sulfonic acid-based water reducing agent Foaming agent: Aluminum powder

[0034]

Table 1

[0035] For siliceous fine powders A to G, commercially available siliceous fine powders were used. The SiO2 content of the siliceous fine powder was measured by a fluorescent X-ray analyzer, the BET specific surface area was measured by the nitrogen adsorption method, the loss on ignition was measured by heating strongly in an electric furnace adjusted to 1000°C for 15 minutes and measuring the weight change before and after the strong heating, and the pH was measured by mixing each siliceous fine powder shown in Table 1 and water with a hand mixer to prepare a slurry with a siliceous fine powder concentration of 50% by mass and measuring the pH of the slurry with a pH meter.

[0036] [Mix design of grout composition] Cement, siliceous fine powder, fine aggregate, water reducing agent and foaming agent were mixed and designed at the ratios shown in Table 2. The coarse grain ratio of the fine aggregate was 3.1 for Examples 1 to 3 and 6 and Comparative Examples 1 to 4, 2.8 for Example 4, and 3.7 for Example 5.

[0037] [Production of grout] The designed grout composition and water were added to a 10 L cylindrical container and kneaded with a hand mixer for 90 seconds to produce grout. Water was added at the ratio shown in Table 2.

[0038] [Evaluation method] The following evaluation method was used to evaluate various grouts. The results are shown in Table 2. Each test was conducted at 20°C. ·Measurement of J funnel flow value: In accordance with the Japan Society of Civil Engineers Standard JSCE-F 541-2013 "Test Method for Fluidity of Grout (Draft)", the J14 funnel flow-down time was measured. · Fluidity test: The fluidity test was carried out in accordance with the flow test of JIS R 5201:2015 "Physical Test Methods for Cement". The flow value was the drawn flow value (0 strikes). · Fluidization time (water familiarity): For a predetermined amount of water, after the grout composition was put in while stirring with a hand mixer, the time (seconds) until the grout composition and water were integrated (the grout was fluidized) was measured visually. If the fluidization time was within 30 seconds, the water familiarity was good. · Compressive strength: In accordance with the Japan Society of Civil Engineers Standard JSCE-G 505-2018 "Test Method for Compressive Strength of Mortar or Cement Paste Using Cylindrical Specimens (Draft)", the compressive strength of the grout hardened body at 28 days of age was measured. The dimensions of the specimens were a diameter of 50 mm and a height of 100 mm. Curing was wet curing in the mold until 24 hours of age. After 24 hours, the mold was removed, and thereafter, water curing was carried out until the predetermined age. For Comparative Examples 1 to 4, since the fluidity of the grout (J funnel flow-down value, flow value) was extremely poor, the compressive strength was not measured.

[0039]

Table 2

[0040] The grout of the example had good water familiarity (fluidization time), the flow-down time was 10 seconds or less, and the table flow value of 0 strikes was 250 mm or more, so the fluidity was also good, and it had excellent workability and showed a high compressive strength of 70 N / mm 2 or more at 28 days of age. On the other hand, the grouts of the comparative examples were not excellent in water familiarity and fluidity.

Claims

1. A grout composition comprising cement, silica fine powder, fine aggregate, and a water reducing agent, wherein in the silica fine powder, the SiO ２ content is 96% by mass or more, the BET specific surface area is 5 to 16 m ２ / g, and the loss on ignition is 1.0% by mass or less.

2. The grout composition according to claim 1, further comprising a foaming agent.

3. The grout composition according to claim 1 or 2, wherein the content of the silica fine powder is 10 to 50 parts by mass with respect to 100 parts by mass of the cement.

4. A grout comprising the grout composition according to claim 1 or 2 and water, wherein the content of the water is 30 to 70 parts by mass with respect to 100 parts by mass of the cement.

5. The grout according to claim 4, wherein the flow-down time of the J14 funnel measured in an environment at 20°C in accordance with the Japan Society of Civil Engineers standard JSCE-F 541-2013 "Test Method for Fluidity of Filling Mortar" is 6 to 10 seconds.

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