hydraulic components

Abstract

To provide medium flow concrete with improved resistance to material separation without lowering the water-powder ratio, while ensuring equivalent flowability compared to medium flow concrete made with ordinary Portland cement alone.SOLUTION: A hydraulic composition of the present invention comprises: a binder consisting of 47 to 89 parts by mass of Portland cement clinker, 10 to 50 parts by mass of ground blast furnace slag powder, and 1 to 3 parts by mass of gypsum (the total amount of binder is 100 parts by mass); a high-performance AE water reducer containing a thickening component; coarse aggregate; fine aggregate; and water. The hydraulic composition has a fine aggregate ratio of 55 to 60%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a hydraulic composition. More specifically, it relates to a hydraulic composition that is fluid, resistant to material separation, and less prone to material separation due to compaction. [Background technology]

[0002] In recent years, construction projects using concrete have seen an increase in cases where filling concrete formwork is difficult due to the increasing complexity of component shapes and the increased amount of reinforcing steel. Furthermore, the decline in the number of workers and engineers inevitably leads to a decrease in work efficiency.

[0003] To address these problems, high-flow concrete that does not require compaction has been developed and is in use. However, this high-flow concrete inevitably increases costs because it requires the use of large amounts of powders such as cement and admixtures such as high-performance air-enhanced water-reducing agents during its manufacture, and it also presents problems such as complicated quality control due to its properties.

[0004] To address the problems in the above-mentioned construction work and the issues with high-flow concrete, the application of "high-flow concrete requiring compaction (hereinafter referred to as medium-flow concrete)," which has higher fluidity than ordinary concrete but requires compaction during construction, is gradually progressing. For example, several cases of its application to tunnel lining concrete have been reported (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Kazuhiko Suwazono, et al., "Construction of Tunnel Lining with Thickening Agent-Based Medium-Flow Concrete - Tsunagi Tunnel (Provisional Name) on the South Kyushu West Bypass Expressway," Concrete Engineering, April 2012, Vol. 50, No. 4, pp. 366-371 (368). [Overview of the project] [Problems that the invention aims to solve]

[0006] Medium-flow concrete has the advantage of being highly fluid and requiring minimal compaction for filling. However, due to the need to minimize cement usage, it tends to have a high water-to-powder ratio and a large unit water content, which makes it prone to material segregation if the compaction time is prolonged. [Means for solving the problem]

[0007] The inventors conducted research to solve the above problems. They found that by replacing the cement used in medium-flow concrete with blast furnace slag fine powder through internal substitution, using a high-performance AE water-reducing agent containing a thickening component, and adjusting the fine aggregate ratio to a predetermined value, it is possible to improve the resistance to material segregation while maintaining fluidity without lowering the water-to-powder ratio of the concrete, thus completing the present invention.

[0008] In other words, the present invention relates to a hydraulic composition comprising a binder consisting of 47 to 89 parts by mass of Portland cement clinker, 10 to 50 parts by mass of blast furnace slag fine powder, and 1 to 3 parts by mass of gypsum (total binder amounting to 100 parts by mass), a high-performance AE water-reducing agent containing a thickening component, coarse aggregate, fine aggregate, and water, wherein the fine aggregate ratio is 55 to 60%. In the hydraulic composition of the present invention, it is preferable that the slump flow value is 40 to 50 cm and the air content is 3.0 to 6.0%. [Effects of the Invention]

[0009] According to the hydraulic composition of the present invention, compared to the case where medium-flow concrete is made using only ordinary Portland cement, it is possible to improve resistance to material segregation without lowering the water-to-powder ratio while ensuring equivalent fluidity, and to provide medium-flow concrete in which material segregation does not occur even at a compaction time of 10 seconds, in which material segregation can occur in ordinary medium-flow concrete. [Modes for carrying out the invention]

[0010] The binder used in the hydraulic composition of the present invention consists of Portland cement clinker, blast furnace slag powder, and gypsum.

[0011] Portland cement clinker is not particularly limited as long as it is the clinker used in the manufacture of ordinary Portland cement according to JIS standards. Generally, the mineral composition shown in the Bogue formula is approximately 50-67% C3S, 12-20% C2S, 7-15% C3A, and 7-15% C4AF.

[0012] The fineness of Portland cement clinker can be within the range of commonly used particles, such as 3000-4500 cm². 2 It is preferable that the amount be adjusted to / g. The powderiness may also be adjusted by adding gypsum.

[0013] The method for producing Portland cement clinker is not particularly limited, and it can be easily obtained by preparing and mixing known cement (clinker) raw materials in predetermined proportions to achieve desired mineral ratios and coefficients, and then firing them in a known method (e.g., an SP kiln or an NSP kiln).

[0014] The method for preparing and mixing the cement raw materials can also be any known method as appropriate. For example, the composition of waste, by-products, and other raw materials (CaO sources such as limestone, quicklime, and slaked lime; SiO2 sources such as silica; Al2O3 sources such as clay; Fe2O3 sources such as iron, etc.) can be measured in advance, and the mixing ratio of each raw material can be calculated from the proportion of each component in these raw materials so that it falls within the above range, and the raw materials can be mixed in that ratio.

[0015] Furthermore, the raw materials used in the manufacture of Portland cement clinker are the same as those conventionally used in the manufacture of Portland cement clinker, without any particular restrictions. It is also possible to utilize waste materials, by-products, etc.

[0016] In the production of Portland cement clinker, it is preferable to use one or more from waste materials, by-products, etc. from the viewpoint of promoting the effective use of waste materials, by-products, etc. More specifically, examples of usable waste materials and by-products include blast furnace slag, steelmaking slag, non-ferrous ore slag, coal ash, sewage sludge, water purification sludge, paper sludge, construction-generated soil, foundry sand, dust, incineration fly ash, molten fly ash, chlorine bypass dust, wood chips, waste bleaching clay, bottles, waste tires, shells, municipal waste and its incineration fly ash, etc. (Among these, there are those that become cement raw materials and heat energy sources.)

[0017] The binder used in the hydraulic composition of the present invention contains, in addition to the above Portland cement clinker, blast furnace slag fine powder and gypsum as essential components.

[0018] As the blast furnace slag fine powder, blast furnace slag fine powder known as a cement admixture can be used. Specifically, those conforming to JIS A 6206 "Blast Furnace Slag Fine Powder for Concrete" can be used without limitation. The fineness of the blast furnace slag fine powder may be within the generally used range, and it is preferably adjusted to 4000 - 5000 cm 2 / g.

[0019] Regarding gypsum, gypsum known as a raw material for cement production such as gypsum dihydrate, hemihydrate gypsum, anhydrous gypsum, etc. can be used without particular limitation. Specifically, by-product gypsum dihydrate such as flue gas desulfurization gypsum, phosphogypsum, etc., natural gypsum dihydrate, hemihydrate gypsum, type II anhydrous gypsum, etc. are included.

[0020] The binder used in the hydraulic composition of the present invention consists of 47 - 89 parts by mass of Portland cement clinker, 10 - 50 parts by mass of blast furnace slag fine powder, and 1 - 3 parts by mass of gypsum (assuming the total amount of the binder is 100 parts by mass). Outside this range, the fluidity decreases or abnormal setting occurs. It is preferably in the range where the Portland cement clinker is 52 - 84 parts by mass, the blast furnace slag fine powder is 15 - 45 parts by mass, and the gypsum is 1 - 3 parts by mass.

[0021] Regarding the grinding method for preparing the fineness of Portland cement clinker, blast furnace slag fine powder, and gypsum powder, which constitute the binder used in the hydraulic composition of the present invention, known techniques can be used without particular limitation. After individually grinding each component, they may be mixed, or they may be ground after mixing. As the grinder, a ball mill, a vertical mill, etc. can be used. Also, it can be produced by mixing the individually produced Portland cement and blast furnace slag fine powder.

[0022] Here, each material of the binder used in the present invention may be used alone, or two of Portland cement (a mixture of Portland cement clinker and gypsum) and blast furnace slag fine powder may be used, or blast furnace cement (a mixture of Portland cement and blast furnace slag) may be used.

[0023] The hydraulic composition of the present invention contains, in addition to the above binder, a high-performance AE water reducer containing a thickening component, coarse aggregate, fine aggregate, and water.

[0024] The high-performance AE water reducer containing a thickening component is mainly composed of a polycarboxylic acid-based compound containing a thickening component, and any one that conforms to JIS A 6204 "Chemical admixtures for concrete" can be used. The addition rate of the high-performance AE water reducer containing a thickening component is not a problem as long as it is within the range recommended by the manufacturer, but 1.0 to 1.5% with respect to the powder mass is preferable. Examples of the high-performance AE water reducer containing a thickening component include Florick SF500F manufactured by Florick Co., Ltd.

[0025] For the coarse aggregate and fine aggregate, known ones used in general concrete production can be used without particular limitation. Specifically, crushed stone, crushed sand, river gravel, hill sand, sea sand, limestone aggregate, etc. For the size of the coarse aggregate, it is preferable to use those with a size of 10 to 25 mm. The usage amount of the coarse aggregate is 700 to 1000 kg / m 3This is preferable. For the fine aggregate, it is preferable to use one with a coarseness ratio of about 2.4 to 2.8, or a mixture of several types of fine aggregate to achieve the specified coarseness ratio. The amount of fine aggregate used is 900 to 1200 kg / m³. 3 This is preferable. Furthermore, the volume ratio of fine aggregate to the total aggregate (hereinafter referred to as the fine aggregate ratio) is 55-60%. If it falls outside this range, the resistance to material segregation decreases or the fluidity decreases. The preferred range for the fine aggregate ratio is 56.5-58.5%.

[0026] Any water used in general concrete production can be used without any particular restrictions. Specifically, tap water, groundwater, etc., can be used as long as they conform to JIS A 5308 "Ready-Mixed Concrete".

[0027] The slump flow value and air content are preferably within the range that conforms to JIS A 5308 "Ready-Mixed Concrete," specifically, a slump flow value of 40-50 cm and an air content of 3.0-6.0% are preferred. By keeping within this range, it is possible to improve the resistance to material segregation while maintaining the fluidity of the concrete, and furthermore, because it conforms to JIS A 5308 "Ready-Mixed Concrete," it is possible to create a highly versatile hydraulic composition.

[0028] The slump flow value and air content are measured according to JIS A 1150 "Test Method for Slump Flow of Concrete" and JIS A 1128 "Test Method for Air Content of Fresh Concrete by Pressure".

[0029] The hydraulic composition of the present invention is a normal-strength concrete controlled by slump flow within the JIS A 5308 "Ready-Mixed Concrete" category, and generally corresponds to medium-flow concrete when the slump flow value is 40-50 cm.

[0030] In the present invention, the method for producing a hydraulic composition by kneading (mixing) Portland cement, finely powdered blast furnace slag, a high-performance AE water reducing agent containing a thickening component, coarse aggregate, fine aggregate and water can be used without particular limitation by the conventional production methods in ready-mixed concrete plants and concrete precast product plants.

[0031] In the present invention, generally, a mixer used for kneading a hydraulic composition can be used without limitation as long as it is a mixer for kneading mortar or concrete. Specifically, examples thereof include a pan mixer, a forced double-shaft mixer, a tilting mixer, a mortar mixer, a hand mixer and the like.

Example

[0032] Hereinafter, the present invention will be described more specifically by way of examples. However, the present invention is not limited to these examples.

[0033] Medium-flow concrete was kneaded using ordinary Portland cement (NC), finely powdered blast furnace slag (BS), a high-performance AE water reducing agent containing a thickening component (admixture), coarse aggregate, fine aggregate and water, and various tests were carried out, and the fresh properties and material segregation resistance were evaluated.

[0034] (Materials used) NC: Ordinary Portland cement manufactured by Tokuyama Corporation (containing 98 parts by mass of Portland cement clinker and 2 parts by mass of gypsum; density 3.16 g / cm 3 , fineness 3210 cm 2 / g), BS: Esment 40P manufactured by Nippon Steel Blast Furnace Cement Co., Ltd. (density 2.91 g / cm 3 , fineness 3980 cm 2 / g), Admixture: Florick SF500F manufactured by Florick Co., Ltd., Coarse aggregate: Hard sandstone crushed stone 2010 produced in Miyano, Yamaguchi City, Yamaguchi Prefecture (apparent dry density 2.69 g / cm 3 ) and 1505 (apparent dry density 2.69 g / cm 3 ), Fine aggregate: Crushed sand produced in Kumehigashi, Shunan City, Yamaguchi Prefecture (apparent dry density 2.66 g / cm3 (Coarse grain ratio 2.79) and hill sand from Onga, Fukuoka Prefecture (Surface dry density 2.58 g / cm³) 3 , coarse grain ratio 1.21) I used it.

[0035] The fine aggregate was mixed with crushed sand and dune sand in a ratio of 81.8%:18.2% so that the coarseness ratio of the synthesized sand was 2.55. The ratio of water to binder (water-to-binder ratio (W / B)) was set at 55%.

[0036] A 100L pan-type forced mixer (TM-100) manufactured by Taiheiyo Kiko Co., Ltd. was used for mixing. The mixing procedure was as follows: first, the powder, coarse aggregate, and fine aggregate were added to the mixer and stirred for 30 seconds, then the admixture and water were added and mixed for 90 seconds. The target fresh properties for the medium-flow concrete were a slump flow value of 45±5cm and an air content of 4.5±1.5%. Table 1 shows the mixing ratio of the binders used in each example, Table 2 shows the level of the medium-flow concrete, and Table 3 shows the results of various tests.

[0037] The various measurement methods are as follows. (1) Slump measurement: Measured according to the method in accordance with JIS A 1101. (2) Measurement of slump flow: Measured according to the method in accordance with JIS A 1150. (3) Measurement of air volume: Measured according to the method in accordance with JIS A 1128. (4) Measurement of coarse aggregate retention rate: The measurement was performed in accordance with the coarse aggregate settlement test, which was considered by the Japan Concrete Institute Concrete Committee 358 Research Subcommittee on Mix Design and Construction Technology for High-Flow Concrete Requiring Compaction.

[0038] Specifically, the test involves pouring 20 liters of concrete into a bucket container with a diameter of 30 cm and a height of 35 cm, inserting a rod-shaped vibrator (Exen Corporation D32D, vibration frequency 200-242 Hz) into the center of the container, 1 cm from the bottom, and vibrating it for a predetermined time. Then, 2 liters of the surface layer of the concrete is collected and wet-screened to wash out the coarse aggregate, and the ratio of the amount of coarse aggregate to the design value is measured. Here, wet screening means washing the concrete using a sieve with a mesh size smaller than or equal to the minimum size of the coarse aggregate, separating the coarse aggregate from the other materials. In this test, the greater the degree of material separation, the more the coarse aggregate settles to the bottom, reducing the amount of coarse aggregate washed out and resulting in a smaller test result. Regarding the vibration time, we set it at 10 seconds, which is the median of the recommended vibration time of "approximately 5 to 15 seconds" for ordinary concrete as described in the Standard Specifications for Concrete and the Standard Specifications and Commentary for Building Construction JASS5. For medium-flow concrete, we set it at 6 seconds because the compaction time is shorter than that of ordinary concrete.

[0039] [Table 1]

[0040] [Table 2]

[0041] [Table 3]

[0042] The reference example was tested using ordinary concrete with a slump value of 18 cm, which is commonly used. The residual aggregate content after 10 seconds of vibration, which is the typical compaction time for concrete, was 75.0%.

[0043] Comparative Examples 1 and 2 were conducted to demonstrate the effects of the binder of the present invention, using conventional techniques such as conventional medium-flow concrete made only with ordinary Portland cement and without blast furnace slag powder. Comparative Example 1 was an example of medium-flow concrete that satisfied the target slump flow value and target air content. The slump flow value was 44.5 cm and the air content was 5.0%, satisfying the target values. However, the coarse aggregate retention rate was 65.2% at a compaction time of 6 seconds and 57.8% at a compaction time of 10 seconds, significantly lower than the values ​​of the reference example. Comparative Example 2 was based on Comparative Example 1, but the water content was increased to 175 kg / m³ to improve the coarse aggregate retention rate. 3 By reducing the compaction time, the coarse aggregate retention rate improved to 88.7% at 6 seconds of compaction and to 74.2% at 10 seconds of compaction, showing a better coarse aggregate retention rate than Comparative Example 1, but the slump flow value decreased to 37.0 cm.

[0044] Comparative Example 3 is an example where the fine aggregate ratio falls outside the range specified in the present invention. Using the same ratio of binder as in Example 3, the fine aggregate ratio was set to 60.6%, which is outside the range specified in the present invention. Although the coarse aggregate retention rate was 86.9% at a compaction time of 6 seconds and 75.1% at a compaction time of 10 seconds, the slump flow value decreased to 36.3 cm. From the results of the comparative example, it can be seen that it is difficult to improve the coarse aggregate retention rate while securing the target slump flow unless the requirements of the present invention are satisfied.

[0045] Examples 1-3 show the results when the binder was mixed in the proportions shown in Table 1 and the mix design conditions were as shown in Table 2. In all three examples, while satisfying the target slump flow value, it was confirmed that a good coarse aggregate retention rate of 80% or more was observed at a compaction time of 6 seconds, and 68% or more was observed at a compaction time of 10 seconds. From this, it can be seen that the present invention can suppress material segregation at 6 seconds, which is an appropriate compaction time for medium-flow concrete, and that even at 10 seconds, which is an appropriate compaction time for ordinary concrete, the degree of material segregation can be suppressed more than that of ordinary medium-flow concrete.

Claims

1. A hydraulic composition comprising a binder consisting of 47 to 89 parts by mass of Portland cement clinker, 10 to 50 parts by mass of blast furnace slag fine powder, and 1 to 3 parts by mass of gypsum (total amount of binder being 100 parts by mass), a high-performance AE water-reducing agent containing a thickening component, coarse aggregate, fine aggregate, and water, characterized in that the fine aggregate ratio is 55 to 60%.

2. The hydraulic composition according to claim 1, wherein the slump flow value is 40 to 50 cm and the air content is 3.0 to 6.0%.

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