Filler for rebar joints

Abstract

A filler for rebar joints, the filler containing cement, an expansive material, silica fume, a water-reducing agent, and a fine aggregate, wherein: the fine aggregate has a wear weight loss of 3% or less using a 0.09-mm sieve in an aggregate wear test carried out using a Los Angeles Machine; and in 100 mass% of fine aggregate, the content ratio of particles having grain sizes of 0.3-2 mm is 60-90 mass%, and the content ratio of particles having grain sizes of less than 0.3 mm is 10-40 mass%.

Description

[Technical Field]

[0001] The present invention relates to a filler for reinforcing bar joints. [Background technology]

[0002] Traditionally, the mortar material used in civil engineering and construction work has generally been cement with a water-reducing agent added. Furthermore, calcium sulfoaluminate-based or lime-based expansive materials, or foaming agents such as aluminum powder, are added to create non-shrinkage materials, and these are mixed with river sand or silica sand to form pastes or mortars. They are particularly widely used in filling small voids in concrete structures, voids in inverted construction, repair and reinforcement of structures, and filling spaces under the base plates of machinery and equipment, as well as under track decks.

[0003] Generally, the mortar material used as a filling material in civil engineering and construction work is called grout, and there are various types of grout, including PC grout, grout for prepacked concrete, backfill grout for tunnels and shields, precast grout, grout for repairing and reinforcing structures, grout for rebar joints, grout under bridge bearings, grout under pavement decks, grout under track decks, and grout under nuclear power plant containment vessels.

[0004] In recent years, the quality of concrete used in civil engineering and architectural structures has improved, and the performance required of mortar materials used as grout has also increased, with high strength, high fluidity, low shrinkage, etc. being required depending on the application.

[0005] In particular, mortar filled in joints connecting reinforcing bars in structures such as reinforced concrete and precast concrete requires increased strength and improved joint strength due to the increasing size of reinforced concrete structures and the increased strength of concrete to improve earthquake resistance. Therefore, mortar with high fluidity, high strength development, and low shrinkage is desired.

[0006] Patent Document 1 describes a cement-based grout composition, for example, as a steel joint grout. It describes a composition consisting of cement, fine aggregate, a water-reducing agent, an expansive agent, an inorganic fine powder, and a foaming substance. The composition describes that the amount of water-reducing agent is 0.05 to 4 parts by mass per 100 parts by mass of cement, and that, per 100 parts by mass of the water-reducing agent, the amounts of a melamine sulfonate-based water-reducing agent are 10 to 30 parts by mass, a naphthalene sulfonate-based water-reducing agent are 55 to 85 parts by mass, and a lignin sulfonate-based water-reducing agent are 5 to 20 parts by mass. It also describes that the expansive agent is preferably one whose main components are free lime, calcium aluminoferrite, and anhydrous gypsum.

[0007] Patent Document 2 describes a cement composition that can also be used as a filler for joints. It contains high-belite cement, silica fume, a cement dispersant primarily composed of a polycarboxylic acid polymer compound having a polyalkylene glycol chain, a lime-based admixture or an organic shrinkage-reducing agent, a substance that generates pressure to counteract the shrinkage force resulting from the hydration reaction of the high-belite cement, and fine aggregate with a specific gravity of 3.4 or higher and a water absorption rate of 0.5 to 1.5%. It also describes that a lime-based expansive agent or a ground mixture of gypsum and clinker containing CaO crystals is preferred as the expansive agent.

[0008] Patent Document 3 describes a filler for reinforcing bar joints and a method of filling reinforcing bar joints using the same. The reinforcing bar joint filler contains cement, an expansive material, a fine pozzolan powder, a water-reducing agent, and fine aggregate, and describes that the expansive material is a calcium aluminoferrite-based expansive material, the fine pozzolan powder is a siliceous powder with a silicon dioxide (SiO2) content of 90% or more and a hydrogen ion concentration in the acidic range, and the water-reducing agent is a polycarboxylic acid-based water-reducing agent. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-171162 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-286064 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-94674 Summary of the Invention [Problem to be solved by the invention]

[0010] With the current trend of constructing many skyscrapers, there is a demand for further improvements in the performance of reinforcing bar joints. In particular, in addition to the technology of Patent Document 3, it is necessary to satisfy high reinforcing bar joint performance other than tensile strength and to provide the effect of preventing settlement of the mortar surface by a low bleeding rate. Under these circumstances, the object of the present invention is to provide a filler for reinforcing bar joints that provides mortar with high fluidity, dimensional stability and high strength in the hardened body, and further prevents cracking by a low bleeding rate. [Means for solving the problem]

[0011] The present inventors have conducted extensive research to solve the above problems, and have discovered that by focusing on the particle size distribution of silica fume, a water-reducing agent, and fine aggregate, as well as the expansive agent used, and on abrasion loss measured with a Los Angeles testing machine, it is possible to obtain a filler for reinforcing bar joints that provides mortar with high fluidity, dimensional stability and high strength in its hardened form, and is suitable for preventing settlement of the mortar surface, and thus have completed the present invention.

[0012] That is, the present invention is as follows. [1] A filler for rebar joints containing cement, an expansive agent, silica fume, a water-reducing agent, and fine aggregate, wherein the fine aggregate has an abrasion loss of 3% or less when measured using a 0.09 mm sieve in an aggregate abrasion test using a Los Angeles testing machine, and the content of particles with a particle size of 0.3 to 2 mm is 60 to 90 mass% of 100 mass% of the fine aggregate, and the content of particles with a particle size of less than 0.3 mm is 10 to 40 mass%. [2] The filler for reinforcing bar joints according to [1], wherein the content of the expansive material is 3 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the cement. [3] A filler for reinforcing bar joints according to [1] or [2], wherein the content of the silica fume is 3 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the cement. [4] The filler for reinforcing bar joints according to any one of [1] to [3], wherein the content of the water reducing agent is 0.05 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the cement. [5] The filler for reinforcing bar joints according to any one of [1] to [4], wherein the content of the fine aggregate is 50 parts by mass or more and 300 parts by mass or less per 100 parts by mass of the cement. [6] The fine aggregate has a density of 2.6 g / cm 3 The filler for reinforcing bar joints according to any one of [1] to [5], which is a heavy aggregate. [7] The filler for reinforcing bar joints according to any one of [1] to [6], which contains a foaming agent. [8] The filler for reinforcing bar joints according to any one of [1] to [7], which contains an antifoaming agent. [Effects of the Invention]

[0013] According to the present invention, the filler for reinforcing bar joints has high fluidity in the mortar, and the hardened body has dimensional stability and high strength, and can prevent cracking. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described in detail below. The specific embodiments shown below are merely examples, and the present invention is not limited to these.

[0015] [Filler for rebar joints] The reinforcing bar joint filler of the present invention contains cement, an expansive material, silica fume, a water-reducing agent, and fine aggregate. The reinforcing bar joint filler of the present invention may further contain a foaming agent and an antifoaming agent. Hereinafter, the cement composition contains cement, an expansive material, silica fume, and a water-reducing agent.

[0016] <Fine aggregate> The fine aggregate used in the present invention is preferably a heavy aggregate, and is not particularly limited as long as it can develop strength and maintain fluidity. Examples include ferronickel slag, ferrochrome slag, olivine, magnetite, hematite, copper slag, and electric furnace oxidizing slag. In the present invention, one or more of these can be used in combination. The density of the fine aggregate is 2.6 g / cm. 3 It is preferable that the concentration is 2.9 g / cm or more. 3 It is more preferable that the density of the fine aggregate is 2.6 g / cm or more. 3 When the weight of the aggregate is above this level, the fluidity of the mortar is good and the materials are less likely to separate. When used as a premix product, dry sand is preferable, and the maximum particle size is preferably 2.0 mm in terms of fluidity. The density of fine aggregate can be measured in accordance with the method specified in JIS A 1109:2006, "Testing Method for Density and Water Absorption of Fine Aggregate."

[0017] Furthermore, the fine aggregate has an abrasion loss of 3% or less on a 0.09mm sieve, as measured by an aggregate abrasion test using a Los Angeles tester. The abrasion loss is preferably 2.5% or less, and even more preferably 2.0% or less. Furthermore, the content of particles with a particle size of 0.3 to 2 mm is preferably 60 to 90% by mass, more preferably 70 to 85% by mass, and the content of particles with a particle size of less than 0.3 mm is preferably 10 to 40% by mass, and more preferably 15 to 30% by mass. Because the fine aggregate has an appropriate hardness and particle size, when used as a filler for rebar joints, the mortar has high fluidity, the hardened body has dimensional stability and high strength, and is crack-resistant. The content ratio of particles with particle diameters of 0.3 to 2 mm and the content ratio of particles less than 0.3 mm were determined by separating particles with particle diameters of 0.3 to 2 mm and less than 0.3 mm using a 0.3 mm sieve and measuring the mass of each.

[0018] The abrasion loss using a 0.09 mm sieve in the aggregate abrasion test using a Los Angeles tester is measured using the following formula in accordance with JIS A 1121:2007 "Test method for abrasion of coarse aggregate using a Los Angeles tester." Wear loss (%) = (m1-m2) / m1 x 100 m1: total mass of the sample before testing (g) m2: Mass (g) of the sample remaining on the 0.09 mm sieve after the test

[0019] The amount of fine aggregate used is preferably 50 to 300 parts by mass, more preferably 50 to 200 parts by mass, per 100 parts by mass of cement. When the amount of fine aggregate used is 50 to 300 parts by mass per 100 parts by mass of cement, the amount of shrinkage is small and the strength and fluidity are high.

[0020] <Expansive material> The expansive additive of the present invention includes calcium sulfoaluminate-based expansive additives, calcium aluminoferrite-based expansive additives, lime-based expansive additives, and gypsum-based expansive additives, among which calcium sulfoaluminate-based expansive additives are preferred. The use of calcium sulfoaluminate-based expansive additives provides excellent bleeding prevention, prevents the mortar surface from sinking, and provides dimensional stability, thereby efficiently preventing cracking of the hardened body.

[0021] Calcium sulfoaluminate-based expansive materials are manufactured by blending CaO raw materials, Al2O3 raw materials, Fe2O3 raw materials, and CaSO4 raw materials in a specified ratio and heat treating them using an electric furnace or rotary kiln, generally at 1,100 to 1,600°C. At heat treatment temperatures of 1,100 to 1,600°C, the resulting expansive material has sufficient expansion performance, but if the heat treatment temperature exceeds 1,600°C, the anhydrous gypsum may decompose.

[0022] Examples of CaO raw materials include limestone and slaked lime, examples of Al2O3 raw materials include bauxite and aluminum ash, examples of Fe2O3 raw materials include copper slag and commercially available iron oxide, and examples of CaSO4 raw materials include gypsum dihydrate, gypsum hemihydrate, and anhydrous gypsum.

[0023] The fineness of the expansive material is 4,000 cm in Blaine value. 2 / g or more 9,000cm 2 / g or less is preferable, and 5,000 cm 2 / g or more 8,000cm 2 The content of the expansive material is preferably 3 parts by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of cement. In this case, the occurrence of bleeding can be suppressed.

[0024] <Silica fume> The silica fume used in this invention is used to achieve good fluidity, bleeding prevention, and strength development, particularly at low water ratios. It is obtained as a by-product in the zirconia manufacturing process, and although its primary particle size is larger than that of conventional silica fume, it is less likely to aggregate. For these reasons, the silicon dioxide (SiO2) content of the silica fume is preferably 85% or more, and more preferably 90% or more. It is preferable that the hydrogen ion concentration is in the acidic range. The hydrogen ion concentration here refers to the value obtained by adding 20 g of silica fume to 100 g of pure water, stirring the mixture with a magnetic stirrer for 5 minutes, and then measuring the hydrogen ion concentration in the suspension with a pH meter.

[0025] Silica fume can be produced, for example, by oxidizing fine silicon metal powder in a flame or by melting fine siliceous raw material powder in a high-temperature flame, by adjusting the heat treatment conditions of the raw material to a collection temperature of 550° C. or higher. Silica fume can also be produced by electromelting zircon sand in an electric furnace, collecting it in a cyclone, etc., and then classifying it.

[0026] The preferred specific surface area of ​​zirconia-derived silica fume is 5 to 13 m2 in terms of BET specific surface area from the viewpoint of fluidity and strength development. 2 / g, and 8 to 12m 2 / g is more preferred.

[0027] The average particle size of zirconia-derived silica fume is larger than that of conventional silica fume collected from exhaust gases generated when producing metallic silicon or ferrosilicon in an arc furnace, which is 0.1 to 0.3 μm, and is preferably about 1 μm or less.

[0028] The amount of silica fume used is preferably 3 to 20 parts by mass, more preferably 5 to 15 parts by mass, per 100 parts by mass of cement. By using 3 to 20 parts by mass of silica fume per 100 parts by mass of cement, sufficient strength is achieved, the ball bearing effect reduces the load during mixing, and excellent fluidity is obtained with a specified amount of water.

[0029] <Water reducing agent> The water reducing agent used in the present invention is a general term for those which have a dispersing effect and an air-entraining effect on cement, and which improve fluidity and increase strength, and specific examples include naphthalene sulfonic acid-based water reducing agents, melamine sulfonic acid-based water reducing agents, lignin sulfonic acid-based water reducing agents, and polycarboxylic acid-based water reducing agents, but in the present invention, polycarboxylic acid-based water reducing agents are preferred. Use of a polycarboxylic acid-based water reducing agent improves fluidity retention.

[0030] The water-reducing agent can be used in either powder or liquid form, but when used as a premix product, powder is preferred. The content of the water-reducing agent per 100 parts by mass of cement in powder form is preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 2 parts by mass.

[0031] High fluidity is obtained when the content of the water-reducing agent is 0.05 to 5 parts by mass per 100 parts by mass of cement. Furthermore, a melamine sulfonic acid-based water-reducing agent and a lignin sulfonic acid-based water-reducing agent can be used in combination within a range that does not impair the effects of the present invention.

[0032] <Foaming agent> In the present invention, in order to obtain initial expansion of the mortar after mixing, a foaming agent that generates gas when mixed with water can be used in combination. The foaming agent is not particularly limited, and examples thereof include metal powder and peroxide. Among them, aluminum powder is preferred in terms of the amount added and the effect. However, since the surface of aluminum powder is easily oxidized and becomes covered with an oxide film, which reduces reactivity, aluminum powder whose surface has been surface-treated with vegetable oil, mineral oil, stearic acid, or the like is preferred.

[0033] The amount of foaming agent used is preferably 0.0001 to 0.003 parts by mass, more preferably 0.0002 to 0.003 parts by mass, and even more preferably 0.001 to 0.002 parts by mass, per 100 parts by mass of cement. An amount of 0.0001 part or more can effectively prevent subsidence of the mortar surface, and an amount of 0.003 part or less can prevent excessive foaming and a decrease in strength.

[0034] <Antifoaming agent> In the present invention, it is preferable to use an antifoaming agent. The antifoaming agent is not particularly limited, but a mixture of a special nonionic surfactant and silica is an example. The amount used is preferably 0.3 parts by mass or less, more preferably 0.1 parts by mass or less, per 100 parts by mass of cement. If the amount is 0.3 parts by mass or less, the defoamed bubbles will not rise in large quantities to the cement mortar surface.

[0035] <Cement> Examples of cements that can be used in the present invention include various types of Portland cement, such as ordinary, early-strength, extra-early-strength, low-heat, and moderate-heat cements; various blended cements obtained by mixing these Portland cements with blast furnace slag, fly ash, silica, limestone fine powder, etc.; and waste-recycled cement, so-called ecocement. Of these, ordinary or early-strength cements are preferred in terms of mixability and strength development.

[0036] From the viewpoint of manufacturing cost and strength development, the Blaine value of cement is set to 2,500 to 7,000 cm 2 / g, and 3,000 to 4,500 cm 2 The Blaine value is determined in accordance with JIS R 5201:2015 "Physical testing methods for cement."

[0037] [Rebar joint filling construction method] The reinforcing bar joint filler of the present invention is used by adding water to the reinforcing bar joint filler, mixing it, and then applying it. Specifically, water is first mixed with the reinforcing bar joint filler to prepare mortar. There are no particular limitations on the method for mixing the mortar, but it is preferable to use a hand mixer with a rotation speed of 900 rpm or more, a normal high-speed grout mixer, or a biaxial forced mixer.

[0038] When mixing with a hand mixer or high-speed grout mixer, a predetermined amount of water is placed in a mixing container such as a pail or mixer, and then the premixed rebar joint filler is added while the mixer is rotating, and the mixture is mixed for at least two minutes. When mixing with a forced mixer, the premixed mixture is added to the mixer, and the predetermined amount of water is added while the mixer is rotating, and the mixture is mixed for at least two minutes. A mixing time of two minutes or more makes it easier to obtain mortar with the appropriate fluidity.

[0039] After the rebar is inserted into the joint, the mixed mortar is filled into the joint, usually using a diaphragm-type manual pump or a squeeze-type mortar pump. The mortar then hardens, and the rebar is firmly fixed in place by the joint.

[0040] The amount of water used in the present invention for mixing is not particularly limited, but is preferably 10 to 30 parts by mass, more preferably 10 to 20 parts by mass, per 100 parts by mass of the reinforcing bar joint filler. Within this range, the fluidity and strength are high. [Example]

[0041] [Experimental Example 1] Cement was mixed with 100 parts by mass of cement and the amounts of expansive additive, silica fume, water-reducing agent, fine aggregate, foaming agent, and antifoaming agent shown in Table 2 to prepare a filler for rebar joints. 15 parts by mass of water was added to 100 parts by mass of the cement composition to prepare a mortar. The flow, bleeding rate, expansion / shrinkage rate, compressive strength, and length change rate of the prepared mortar were measured at a temperature of 20°C.

[0042] <Materials used> (a) Cement: Ordinary Portland cement, Blaine value 3,300 cm 2 / g, commercially available (b) Expanding agent: calcium sulfoaluminate, Blaine value 6,000 cm 2 / g, commercially available (c) Silica fume: Silica fume containing zirconium oxide, zirconium oxide content 5%, BET specific surface area 12 m 2 / g, pH 3.0, commercially available (d) Water reducing agent: Polycarboxylic acid-based water reducing agent, commercially available (e) Fine aggregate The content percentage of fine aggregate shown below is rounded to the nearest 10% by mass. (e-1) Fine aggregate A: Ferro-nickel slag aggregate, density 3.11 g / cm 3 , maximum aggregate diameter 2.0mm, aggregate abrasion loss by Los Angeles tester (using 0.09mm sieve) 1.2%, content of particles 0.3-2mm by mass 80%, content of particles less than 0.3mm by mass 20%, commercially available (e-2) Fine aggregate B: Ferrochrome slag aggregate, density 3.12 g / cm 3, maximum aggregate diameter 2.0mm, aggregate abrasion loss by Los Angeles tester (using 0.09mm sieve) 1.4%, content of particles 0.3-2mm by mass 80%, content of particles less than 0.3mm by mass 20%, commercially available (e-3) Fine aggregate C: olivine aggregate, density 3.00g / cm 3 , maximum aggregate diameter 2.0mm, aggregate abrasion loss by Los Angeles tester (using 0.09mm sieve) 0.9%, content of particles 0.3-2mm by mass 80%, content of particles less than 0.3mm by mass 20%, commercially available (e-4) Fine aggregate D: Ferro-nickel slag aggregate, density 3.11 g / cm 3 , maximum aggregate diameter 2.0mm, aggregate abrasion loss by Los Angeles tester (using 0.09mm sieve) 1.2%, content of particles 0.3-2mm by mass 20%, content of particles less than 0.3mm by mass 80%, commercially available (e-5) Fine aggregate E: Ferro-nickel slag aggregate, density 2.95 g / cm 3 , maximum aggregate diameter 2.0mm, aggregate abrasion loss by Los Angeles tester (using 0.09mm sieve) 3.9%, content of particles 0.3-2mm by mass 80%, content of particles less than 0.3mm by mass 20%, commercially available (e-6) Fine aggregate F: Steelmaking slag aggregate, density 3.61 g / cm 3 , maximum aggregate diameter 2.0mm, aggregate abrasion loss by Los Angeles tester (using 0.09mm sieve) 2.5%, content of particles 0.3-2mm by mass 80%, content of particles less than 0.3mm by mass 20%, commercially available (e-7) Fine aggregate G: Silica sand, density 2.60g / cm 3 , maximum aggregate diameter 2.0mm, aggregate abrasion loss by Los Angeles tester (using 0.09mm sieve) 4.8%, content of particles 0.3-2mm by mass 80%, content of particles less than 0.3mm by mass 20%, commercially available (e-8) Fine aggregate H: Limestone aggregate, density 2.60 g / cm 3 , maximum aggregate diameter 2.0mm, aggregate abrasion loss by Los Angeles tester (using 0.09mm sieve) 4.0%, content of particles 0.3-2mm by mass 80%, content of particles less than 0.3mm by mass 20%, commercially available (e-9) Fine aggregate I: Ferrochrome slag aggregate, density 3.10 g / cm 3 , maximum aggregate diameter 2.0mm, aggregate abrasion loss by Los Angeles tester (using 0.09mm sieve) 4.0%, content of particles 0.3-2mm by mass 20%, content of particles less than 0.3mm by mass 80%, commercially available (e-10) Fine aggregate J: Ferro-nickel slag aggregate, density 3.11 g / cm 3 , maximum aggregate diameter 2.0mm, aggregate abrasion loss by Los Angeles tester (using 0.09mm sieve) 1.2%, content of particles 0.3-2mm by mass 60%, content of particles less than 0.3mm by mass 40%, commercially available (e-11) Fine aggregate K: Ferro-nickel slag aggregate, density 3.11 g / cm 3 , maximum aggregate diameter 2.0mm, aggregate abrasion loss by Los Angeles tester (using 0.09mm sieve) 1.2%, content of particles 0.3-2mm by mass 90%, content of particles less than 0.3mm by mass 10%, commercially available (e-12) Fine aggregate L: Ferro-nickel slag aggregate, density 3.05 g / cm 3 , maximum aggregate diameter 2.0mm, aggregate abrasion loss by Los Angeles tester (using 0.09mm sieve) 3.0%, content of particles 0.3-2mm by mass 80%, content of particles less than 0.3mm by mass 20%, commercially available (e-13) Fine aggregate M: Ferro-nickel slag aggregate, density 3.11 g / cm 3 , maximum aggregate diameter 2.0mm, aggregate abrasion loss by Los Angeles tester (using 0.09mm sieve) 1.2%, content of particles 0.3-2mm by mass 100%, content of particles less than 0.3mm by mass 0%, commercially available (f) Foaming agent: Aluminum powder (surface-treated), commercially available (g) Antifoaming agent: A mixture of special nonionic surfactant and silica, commercially available (h) Water: Tap water Table 1 shows the fine aggregates A to M.

[0043] [Table 1]

[0044] <Evaluation method> (1) Flow: Measured in accordance with JASS 15 M-103 "Quality Standards for Self-Leveling Materials." A Φ50 x 100 mm polyvinyl chloride resin pipe was used as the flow container. Mortar was filled into the pipe and then pulled up. After the mortar stopped spreading, the diameters in two perpendicular directions were measured, and the average value was taken as the flow value. (2) Bleeding rate: In accordance with JSCE-F 542-1999, the mortar prepared in each example and comparative example was placed in a container, and three hours later, the bleeding water was collected. The ratio of the amount of bleeding water to the volume of the sample was taken as the bleeding rate. (3) Expansion and shrinkage rate: In accordance with JSCE-F 542-1999, the depth from the top surface of the bridge to the glass plate was measured 24 hours after the mortar prepared in each example and comparative example was placed in the formwork, and the expansion and shrinkage rate was calculated from the difference from the base length. (4) Compressive strength: Measured in accordance with JSCE-G 505-1999. The size of the specimen was φ50mm x 100mm, and after one day it was demolded and cured in water. Tests were conducted on specimens aged 28 days, and the compressive strength was determined. (5) Length change rate: Measured in accordance with JIS A 6202:2017 Appendix A "Test method for expansive additive mortar expansion." The specimen was cured underwater after one day, and the length change rate was calculated from the length of the specimen after seven days. The results are shown in Table 2.

[0045] [Table 2]

[0046] From Table 2, it can be seen that the filler for rebar joints used in the examples has a relatively high flow rate, which gives the mortar high fluidity, a relatively low bleeding rate, which prevents the mortar surface from subsiding, a relatively low expansion / shrinkage rate, which gives the hardened body dimensional stability, which prevents cracking of the hardened body, and a relatively high compressive strength, which gives the hardened body high strength. Using the conditions shown in these examples as a reference, Experimental Example 2, shown below, was carried out.

[0047] [Experimental Example 2] A filler for rebar joints was prepared from 100 parts by mass of cement, 10 parts by mass of expansive additive, 10 parts by mass of silica fume, 0.5 parts by mass of water-reducing agent, 0.001 parts by mass of foaming agent, 0.1 parts by mass of antifoaming agent, and the types and amounts of fine aggregate shown in Table 3. Mortar was prepared by adding 15 parts by mass of water to 100 parts by mass of the cement composition. The materials used for the mortar were the same as those in Experimental Example 1.

[0048] As in Experimental Example 1, the flow, bleeding rate, expansion / shrinkage rate, compressive strength, and rate of change in length of the prepared mortar were measured at a temperature of 20°C. Next, the rebars used were those specified in JIS G 3112:2010 "Steel bars for reinforced concrete" with the type symbol SD490 and designation D32, and the joints were S10U / II, using the post-grouting method.After inserting the rebar into the joint, mixed mortar was filled into the joint's injection port using a diaphragm-type manual pump, and after confirming that the mortar was being discharged from the joint's air outlet, the mortar filling was completed, thereby creating a rebar joint specimen.

[0049] The prepared rebar joint specimens were cured in a 20°C constant temperature room until the specified age (28 days), and then tested according to the method specified in the "Rebar Joint Performance Judgment Standards" described in the "2007 Edition: Commentary on Technical Standards Related to Building Structures." The evaluation was based on whether the rebar joint filler after curing at 20°C met the A-class performance specified in the "Rebar Joint Performance Judgment Standards."

[0050] <Reinforcing bar joint performance criteria> The rebar joint specimens were subjected to unidirectional tensile tests, unidirectional cyclic tests, elastic region positive and negative cyclic tests, and plastic region positive and negative cyclic tests to determine the tensile strength, stiffness reduction rate, slippage, and toughness, and it was confirmed whether each met the rebar joint performance criteria (Class A). 1c E. 20c E is 0.95δ at the first and 20th loading, respectively. y0is the secant stiffness of the jointed rebar at stress 20c δ s , 4c δ s are the slip deformations of the joint rebar at the 20th and 4th loading, respectively, and ε u is the ultimate strain of the jointed rebar, and ε y is the yield strain of the bonded rebar. The results are shown in Table 3 along with the rebar joint performance criteria (Class A).

[0051] [Table 3]

[0052] From Table 3, it was found that the reinforcing bar joint specimens of the examples met the reinforcing bar joint performance evaluation criteria (Class A). From this, it can be determined that the filler for reinforcing bar joints of the present invention can achieve high reinforcing bar joint performance and can connect reinforcing bars sufficiently firmly using joints.

Claims

1. A filler for reinforcing bar joints containing cement, an expansive agent, silica fume, a water-reducing agent, and fine aggregate, wherein the fine aggregate has an abrasion loss of 3% or less when measured using a 0.09 mm sieve in an aggregate abrasion test using a Los Angeles testing machine, and the content of particles with particle diameters of 0.3 to 2 mm is 60 to 90 mass% of 100 mass% of the fine aggregate, and the content of particles with particle diameters less than 0.3 mm is 10 to 30 mass%.

2. The filler for reinforcing bar joints according to claim 1, wherein the content of the expansive material is 3 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the cement.

3. 3. The filler for reinforcing bar joints according to claim 1, wherein the content of the silica fume is 3 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the cement.

4. The filler for reinforcing bar joints according to any one of claims 1 to 3, wherein the content of the water reducing agent is 0.05 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the cement.

5. The filler for reinforcing bar joints according to any one of claims 1 to 4, wherein the content of the fine aggregate is 50 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the cement.

6. The fine aggregate has a density of 2.6 g / cm ３ The filler for reinforcing bar joints according to any one of claims 1 to 5, which is a heavy aggregate.

7. The filler for reinforcing bar joints according to any one of claims 1 to 6, which contains a foaming agent.

8. The filler for reinforcing bar joints according to any one of claims 1 to 7, which contains an antifoaming agent.

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