Underwater non-dispersible mortar composition and member thereof

Abstract

To provide an underwater non-dispersible mortar composition having characteristics of low strength, high fluidity, and difficulty in becoming turbid, and to provide an underwater non-dispersible mortar member.SOLUTION: An underwater non-dispersible mortar composition according to the present invention comprises water, cement, fine aggregate, and an underwater non-dispersible admixture. A water-cement ratio is 140% or more, and a content of the underwater non-dispersible admixture is 3.0 kg / m3 or more. It is preferable that the underwater non-dispersible mortar composition according to the present invention further comprise an AE water-reducing agent, and a content of the AE water-reducing agent be 1.00 to 5.00 kg / m3. An underwater non-dispersible mortar member according to the present invention is made of the above underwater non-dispersible mortar composition.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an underwater non-segregating mortar composition and a member made of the underwater non-segregating mortar composition. [Background technology]

[0002] When constructing structures in bodies of water such as rivers, lakes, coastlines, harbors, and oceans, underwater non-segregating hydraulic compositions (mortar compositions, concrete compositions) are used, which have the characteristic that the materials do not easily separate even underwater. Various techniques have been proposed for hydraulic compositions that do not separate underwater.

[0003] For example, Patent Document 1 proposes an underwater non-separating mortar composition that contains a polycarboxylic acid-based water-reducing agent and a thickener, and the polycarboxylic acid-based water-reducing agent contains one or more alkali metals and one or more alkaline earth metals as chemical components. In addition, Patent Document 2 discloses a method for producing a viscoelastic composition containing an expanding agent, an accelerator, and a thickener, the expanding agent having a Blaine specific surface area of ​​4,000 to 7,000 cm 2 / g, and the blending amount of the expanding material is 10 to 30 kg / m 3 and the blending amount of the accelerator is 10 to 40 kg / m 3 An underwater non-segregating concrete composition has been proposed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-114692 [Patent Document 2] Japanese Patent Application Publication No. 2017-031037 Summary of the Invention [Problem to be solved by the invention]

[0005] The underwater non-segregating hydraulic compositions proposed in Patent Documents 1 and 2 are technologies aimed at improving early strength (compressive strength at the age of 24 hours or 18 hours). Meanwhile, the present inventors have conducted detailed studies on the properties required for an underwater non-segregating mortar composition and have arrived at the following points.

[0006] In some cases, the mortar material (hardened body) that has been applied underwater must be excavated using a shield tunneling machine or similar. In such cases, if the mortar material has a high compressive strength, excavation takes time and can cause wear and damage to the cutter bit. Therefore, the underwater non-segregating mortar composition may be required to have the property of "low strength." Furthermore, when using a concrete plant ship to install mortar components on the seabed, the time required to re-moor the ship (such as retrieving and setting up the anchor) is time-consuming, and the varying oceanographic conditions severely limit the construction period. Furthermore, it is necessary to avoid time-wasting situations such as clogging of the mortar composition in the piping during construction. Therefore, in order to improve workability and enable the work to be completed within the limited construction period, underwater non-segregating mortar compositions may be required to have the property of "high fluidity." Furthermore, when the mortar composition is applied underwater, the release of constituent components from the mortar composition may cause the water around the application site to become turbid. Therefore, there are cases where the underwater non-segregating mortar composition is required to have the property of being "resistant to becoming turbid." Therefore, the present inventors wanted to create an underwater non-segregating mortar composition that has all of the properties of "low strength," "high fluidity," and "low turbidity."

[0007] From this viewpoint, an object of the present invention is to provide an underwater non-separating mortar composition and an underwater non-separating mortar member that have the properties of low strength, high fluidity, and resistance to turbidity. [Means for solving the problem]

[0008] The above problems can be solved by the following means. The underwater non-segregation mortar composition according to the present invention is an underwater non-segregation mortar composition containing water, cement, fine aggregate, and an underwater non-segregation admixture, wherein the water-cement ratio is 140% or more, and the content of the underwater non-segregation admixture is 3.0 kg / m 3 That's all. According to the present invention, since the water-cement ratio is equal to or greater than a predetermined value and the content of the underwater anti-segregation admixture is equal to or greater than a predetermined value, the three properties of low strength, high fluidity, and resistance to turbidity can be exhibited. The underwater non-segregating mortar composition according to the present invention contains an air-entraining water-reducing agent, and the content of the air-entraining water-reducing agent is 1.00 to 5.00 kg / m 3 In the underwater non-segregation mortar composition according to the present invention, the underwater non-segregation admixture preferably contains a water-soluble cellulose ether. In the underwater non-segregation mortar composition according to the present invention, the water-cement ratio is preferably 150 to 200%, and the content of the underwater non-segregation admixture is preferably 4.3 to 5.0 kg / m 3 It is preferable that: According to the present invention, the three properties of low strength, high fluidity, and resistance to turbidity can be more reliably exhibited. The underwater non-segregating mortar member according to the present invention comprises the above-mentioned underwater non-segregating mortar composition. According to the present invention, the underwater non-separating mortar member can exhibit three properties: low strength, high fluidity, and resistance to turbidity. [Effects of the Invention]

[0009] The underwater non-separating mortar composition and the underwater non-separating mortar member according to the present invention have the properties of low strength, high fluidity, and resistance to turbidity. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a graph showing the compressive strength of Samples 1 to 3 at each age. [Figure 2] 1 is a graph showing the relationship between the cement-water ratio and the compressive strength at 28 days for Samples 1 to 3. [Figure 3] 1 is a graph showing the compressive strength of Sample 4 at each age. DETAILED DESCRIPTION OF THE INVENTION

[0011] The underwater non-separating mortar composition and the underwater non-separating mortar member according to this embodiment will be described below. [Underwater non-segregating mortar composition] The underwater non-segregation mortar composition according to this embodiment contains water, cement, fine aggregate, and an underwater non-segregation admixture, has a water-cement ratio of at least a predetermined value, and contains at least a predetermined value of the underwater non-segregation admixture. The underwater non-segregation mortar composition according to this embodiment may also contain an AE water-reducing agent. Each of the constituent elements will be described in detail below.

[0012] (Underwater non-segregating admixture) The underwater anti-segregation admixture is an admixture used in a mortar composition to be cast in water, and is an admixture that inhibits material segregation in water by its thickening effect. For example, the underwater non-separating admixture may be an agent containing water-soluble cellulose ether as the main component (specifically, the content of this component is 70 w / w% or more). More specifically, the underwater non-separating admixture may be Asuka Clean (registered trademark) manufactured by Shin-Etsu Chemical Co., Ltd., Taiheiyo Elcon (registered trademark) manufactured by Taiheiyo Materials Co., Ltd., or Hydrocrete (registered trademark) UWE (registered trademark) manufactured by Mitsui Chemicals Industrial Products, Inc.

[0013] The content of the anti-segregation admixture in water in the mortar composition is 3.0 kg / m 3 More than 3.5 kg / m is preferable. 3 More than 4.0kg / m 3 More than 4.3kg / m 3 More than 4.5kg / m 3 The above is more preferable. When the content of the underwater non-segregation admixture is equal to or greater than a predetermined value, separation of the materials in water is suppressed, and the mortar composition can exhibit the effect of being "less likely to become cloudy" during construction, etc. On the other hand, the upper limit of the content of the underwater anti-segregation admixture in the mortar composition is not particularly limited, and is, for example, 10.0 kg / m 3 Below, 7.0kg / m 3 Below 5.0kg / m 3 The following is the result.

[0014] (water-cement ratio) The water-cement ratio (= water content (kg / m)) in the mortar composition 3 ) / Cement content (kg / m 3 ) × 100) is preferably 140% or more, more preferably 145% or more, and even more preferably 150% or more. When the water-cement ratio is equal to or greater than the predetermined value, the mortar member after construction has a "low strength" and the mortar composition exhibits the effect of "high fluidity" during construction, etc. On the other hand, the upper limit of the water-cement ratio in the mortar composition is not particularly limited, and is, for example, 250% or less, 220% or less, or 200% or less. Instead of the water-cement ratio, the cement-water ratio (= cement content (kg / m 3 ) / water content (kg / m 3 )) is used as a parameter, the cement-water ratio is, for example, 0.40 or more, 0.45 or more, 0.50 or more, and 0.714 or less, 0.69 or less, 0.67 or less.

[0015] The water is not particularly limited, and tap water, sludge water, etc. can be used. The water content in the mortar composition is, for example, 300 kg / m 3 More than 330kg / m 3 More than 360kg / m 3 or more, 450 kg / m 3 Below 400kg / m 3 Below 390kg / m 3 The following is the result. Examples of cement include ordinary Portland cement, high-early-strength Portland cement, ultra-high-early-strength Portland cement, moderate-heat Portland cement, low-heat Portland cement, and sulfate-resistant Portland cement, as specified in JIS R5210:2019. One or more types may be used. In addition to cement, blast furnace slag, fly ash, and the like may also be included as binders. The cement content in the mortar composition is, for example, 130 kg / m 3 More than 150kg / m 3 More than 180kg / m 3 or more, 450 kg / m 3 Below 400kg / m 3 Below 390kg / m 3 The following is the result.

[0016] (fine aggregate) Examples of fine aggregate include mountain sand, river sand, sea sand, crushed sand, silica sand, lime sand, and washed sand, and those that comply with JISA5005:2020 can be used. The content of fine aggregate in the mortar composition is, for example, 800 kg / m 3 More than 1000kg / m 3 More than 1300kg / m 3 or more, 1600 kg / m 3 Below 1500kg / m 3 Below 1400kg / m 3 The following is the result.

[0017] (AE water reducing agent) AE water-reducing agents are a type of chemical admixture specified in JISA6204:2011, and are admixtures with air-entraining properties. The content of AE water-reducing agent in the mortar composition is 1.00 kg / m 3 More than 2.00 kg / m is preferable. 3 More than 3.00kg / m 3 More than 3.50kg / m 3 The above is more preferable. When the content of the AE water-reducing agent is equal to or greater than the predetermined value, the mortar composition can more reliably exhibit "high fluidity." On the other hand, the upper limit of the content of the AE water-reducing agent in the mortar composition is not particularly limited, and is, for example, 5.0 kg / m 3 Below 4.5kg / m 3 Below, 4.0kg / m 3 The following is the result.

[0018] (fine limestone powder) The mortar composition according to the present embodiment may contain limestone fine powder instead of part of the cement in order to achieve a water-cement ratio of at least a predetermined value. The limestone fine powder is not particularly limited, but is preferably one that complies with the specifications of JISA5008-1995. The content of limestone fine powder in the mortar composition is, for example, 50 kg / m 3 More than 80kg / m 3 More than 150kg / m 3 or more, 300 kg / m 3 Below 200kg / m 3 Below 190kg / m 3 The following is the result.

[0019] (others) The mortar composition according to this embodiment may contain, as appropriate, conventionally known materials used in mortars (such as fibers, chemical admixtures specified in JISA6204:2011 other than the above-mentioned underwater non-segregating admixtures and AE water-reducing agents), as long as the desired effects of the present invention are not impaired.

[0020] (Physical properties: compressive strength) The compressive strength of the mortar composition according to this embodiment in water at 28 days is 5.00 N / mm 2 Preferably less than 4.00N / mm 2 Below, 3.80N / mm 2 The following is more preferable: By having a compressive strength of a predetermined value or less, the strength of the mortar member after construction can be more reliably reduced, making the member suitable for processing such as excavation.

[0021] (Physical properties: Intensity ratio in water and air) The underwater and air strength ratio of the mortar composition according to this embodiment (= compressive strength in water at 28 days old (N / mm 2 ) / Compressive strength in air at 28 days (N / mm 2 )) is preferably 0.76 or more, more preferably 0.78 or more. When the underwater / air strength ratio is a predetermined value or more, the mortar composition can more reliably exhibit its resistance to turbidity, and the risk of turbidity of water around the construction site can be avoided.

[0022] (Physical properties: slump flow) The slump flow value of the mortar composition according to this embodiment is preferably 590 mm or more, more preferably 600 mm or more. By having a slump flow value equal to or greater than a predetermined value, the mortar composition can more reliably exhibit its high fluidity characteristics, and prolongation of the construction period can be avoided.

[0023] [Underwater non-segregating mortar components] The underwater non-separating mortar member according to this embodiment is a member (hardened body after construction) made of the above-mentioned underwater non-separating mortar composition. Furthermore, the underwater non-separating mortar component of this embodiment is highly fluid and does not easily become cloudy during construction, and exhibits low strength after construction, so as mentioned above, it is preferably applied to structures in water areas where the construction period is limited, and more preferably to structures that require processing (such as excavation) after construction.

[0024] [Underwater non-segregating mortar composition and method for manufacturing components thereof] The method for producing an underwater non-separating mortar composition according to this embodiment includes the steps of preparing the above-mentioned materials, and the method for producing an underwater non-separating mortar member according to this embodiment includes the steps of mixing, pouring, etc., after the above-mentioned steps. The treatment in each step may be carried out under conditions generally used for producing a mortar composition or a mortar member. [Example]

[0025] [sample] Tables 1 and 2 show the formulations of the samples (mortar compositions) used in the examples. The materials shown in Tables 1 and 2 are as follows: Cement: Ordinary Portland cement (Ube Mitsubishi Cement Co., Ltd.) Fine aggregate: washed sand (Daiichi Sekisan Transport Co., Ltd.) Underwater anti-separation agent: Taiheiyo Elcon (Taipei Material Co., Ltd.) AE water reducing agent: FLORIC (registered trademark) S (FLORIC Co., Ltd.) Limestone powder: Microncal (registered trademark) MC-75 (Asahi Komatsu Co., Ltd.) The air volume in the table is a value measured in accordance with JISA1128:2020, and the mortar temperature is a value measured by measuring the mixed sample with a commercially available thermometer.

[0026] [Table 1]

[0027] [Table 2]

[0028] (Test content: Compression strength test) The air specimen was prepared in accordance with JISA1132:2020, and the underwater specimen was prepared in accordance with JSCE-F504-1999, as follows: For the air specimens, the materials listed in Tables 1 and 2 were mixed and then poured into a formwork (inner diameter 100 mm, height 200 mm). The mixture was then cured in an atmosphere of 20°C until it reached the specified age, and the formwork was removed to prepare the air specimens. For the underwater specimens, the materials listed in Tables 1 and 2 were mixed and then poured in approximately 10 batches into a formwork (inner diameter 100 mm, height 200 mm) placed with its opening facing upwards in a tank filled with tap water. The formwork filled with the materials was then removed from the tank and allowed to cure in an atmosphere of 20°C until the specified age was reached, after which the formwork was removed to prepare the underwater specimens. Compressive strength tests were conducted on each specimen in accordance with JISA1108:2018. The underwater and air strength ratio is calculated by the following formula: 2 ) / Compressive strength in air at each age (N / mm 2 ) was calculated.

[0029] (Test content: Slump flow test) The slump flow test was carried out on each sample (mortar composition) after mixing in accordance with JISA1150:2020. The temperature at the test site was approximately 20°C.

[0030] (Test content: visual test) In the visual test, when preparing the test specimens for underwater use in the compressive strength test described above, it was visually confirmed whether or not turbidity occurred in the water tank. The visual test was evaluated on two levels: "pass" (no turbidity occurred or acceptable turbidity occurred) and "fail" (unacceptable turbidity occurred).

[0031] (Evaluation criteria: low strength) "Low strength" was evaluated based on the compressive strength in water at 28 days old (compressive strength of test specimen for underwater use). Specifically, the compressive strength in water at 28 days is 5N / mm 2 The following cases were rated as "low strength":

[0032] (Evaluation criteria: high flow) "High flow" was evaluated based on the slump flow value. Specifically, a sample having an average slump flow value of 590 mm or more was evaluated as having "high fluidity."

[0033] (Evaluation criteria: resistance to turbidity) The "resistance to turbidity" was evaluated based on the underwater / air intensity ratio and the results of a visual test. Specifically, if the underwater / air strength ratio was 0.76 or higher and the visual inspection test was passed, the product was evaluated as "very resistant to turbidity" (non-separation indicated by a circle in the table); if either of these conditions was met, the product was evaluated as "resistant to turbidity" (non-separation indicated by a triangle in the table); and if neither of these conditions was met, the product was evaluated as "prone to turbidity" (non-separation indicated by an x ​​in the table).

[0034] (Discussion of results) Fig. 1 is a graph showing the compressive strength at each age of Samples 1 to 3. Fig. 2 is a graph showing the relationship between the cement-water ratio and the compressive strength at an age of 28 days for Samples 1 to 3. Fig. 3 is a graph showing the compressive strength at each age of Sample 4. In addition, the compressive strength in water at 28 days in Figure 2 is 4.00 N / mm 2 In other words, it was confirmed that the water-cement ratio was 150% (cement-water ratio was 0.67) when low strength was ensured (thick line in Fig. 2). Therefore, Sample 4 shown in Fig. 3 and Table 2 adopted the water-cement ratio (150%) and set the content of the underwater anti-segregation admixture at 4.5 kg / m 3 The amount of the sample was increased to 100%.

[0035] The results in Figure 1 and Table 1 confirm that the compressive strength decreases as the water-cement ratio increases. Furthermore, it was confirmed that when the water-cement ratio exceeds a certain value, not only high fluidity but also low strength can be achieved. In addition, according to the results in Figure 2, there is a correlation between the cement-water ratio and the compressive strength in water at 28 days, and the compressive strength is 4.0 N / mm 2 It was confirmed that if the desired value is to be less than this, the water-cement ratio should be set to 150% or more (cement-water ratio should be 0.67 or less).

[0036] Comparing Sample 4 shown in Figure 3 and Table 2 with Samples 1 to 3 shown in Figure 1 and Table 1, it was confirmed that the effect of "less likely to become cloudy" can be more reliably achieved as the content of the underwater anti-segregation admixture increases. Furthermore, based on the results of Sample 4, it was confirmed that the effects of "low strength," "high fluidity," and "resistance to turbidity" could be achieved simultaneously.

Claims

1. An underwater non-segregating mortar composition containing water, cement, fine aggregate, and an underwater non-segregating admixture, The water-cement ratio is 140% or more, The content of the underwater non-segregating admixture is 3.0 kg / m ３ The underwater non-segregating mortar composition characterized by the above.

2. Contains AE water reducing agent, The content of the AE water reducing agent is 1.00 to 5.00 kg / m ３ 2. The underwater non-segregating mortar composition according to claim 1, wherein

3. 3. The underwater non-segregating mortar composition according to claim 1, wherein the underwater non-segregating admixture contains a water-soluble cellulose ether.

4. The water-cement ratio is 150 to 200%, The content of the underwater non-segregating admixture is 4.3 to 5.0 kg / m ３ 3. The underwater non-segregating mortar composition according to claim 1 or 2, wherein

5. An underwater non-segregating mortar member comprising the underwater non-segregating mortar composition according to claim 1 or 2.

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