JP4863383B2 - Shell-containing concrete and method for producing the same - Google Patents

Description

  The present invention relates to concrete using a shell as an aggregate and a method for producing the same.

  Shells such as scallops and oysters are industrial wastes generated by processing marine products in the production area, and their treatment is important due to demands for environmental protection and the like, and their recycling is a problem. As a part of such recycling, various proposals for mixing shells into concrete have been made so far, many of which are, for example, concrete moldings for fishing ground facilities of Patent Document 1 and molding methods thereof, and fishing reefs of Patent Document 2 As in the case of blocks, reef block manufacturing methods, and reef block use methods, scallops and oysters are mixed into the concrete as it is for the purpose of purifying water and improving bioadhesion. It was a block with protrusions and recesses made by protruding shells, a method for manufacturing the block, and the like.

In addition, a technique for utilizing a shell as an aggregate for concrete has also been proposed. For example, as in cement concrete of Patent Document 3, shell concrete of Patent Document 4 and a manufacturing method thereof, the shell is made of fine aggregate or coarse aggregate. Is disclosed for blending concrete that is crushed so as to conform to the standard particle size and replaced with fine aggregate or coarse aggregate.
JP 2003-61504 A JP 2000-41525 A Japanese Patent Laid-Open No. 06-271348 JP 2004-51407 A

  Attempts to mix shells with concrete are mainly aimed at the effective use of recycling shells that are marine waste. Patent Documents 1 and 2 of the prior art described above are advantageous in terms of both the recycling rate per unit amount and the manufacturing cost because the shells are mixed into the concrete without changing the hands, but the original performance and quality of the concrete, that is, The strength cannot be expected, but it is rather a defective product for concrete. Therefore, the use is limited to the case where it is used as a biological adhesion floor of a fishing reef.

  In Patent Documents 3 and 4, since the shell is used as an aggregate, the finished concrete can be used in a large amount as ordinary concrete. However, in order to use it as a fine aggregate, it takes time and labor to finely pulverize the shell, and there is no technical problem, but the cost increases. On the other hand, in order to use it as a coarse aggregate, it is necessary to pulverize like a fine aggregate, but the cost is low because coarse pulverization is sufficient. However, a shell, for example, a scallop has a flat shape as shown in FIG. 1 (a). Even if this shell is roughly crushed, as a coarse aggregate as shown in FIG. 1 (b), Since it is still flat and directional, the performance rate is also poor. Further, the surface of the shell has a pore structure and has high water absorption. For this reason, when the coarsely crushed shell is used as the coarse aggregate of concrete, predetermined workability cannot be obtained, and the strength of the concrete after solidification tends to vary.

  The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a shelled concrete having a good balance between shell recycling rate, cost, and quality, and a method for manufacturing the same.

  In order to achieve the above object, as a result of intensive studies and research by the present inventors, the present invention is a flat material for shells such as scallops and oysters, and replaces all coarse aggregates with shells in shelled concrete. Rather, it is preferable to use a mixture of crushed stone and shells as the coarse aggregate. The mixing ratio of the shells is most effective when the volume ratio is 60% at maximum, and the shell is the standard particle size of the coarse aggregate. However, if the particle size of the shell is 20 mm or less, the fine particles of 5 mm or less are contained in an amount of about 30 to 50%, and the fine particles of 75 μm or less are mixed so as to be 5% or less, the concrete is mixed. The present inventors have obtained the knowledge that sometimes good workability can be obtained and the predetermined strength is satisfied, and the present invention has been achieved.

That is, the shell-concrete concrete according to the present invention is obtained by mixing shell chips obtained by crushing shells such as scallops and oysters with a portion of the coarse aggregate of concrete, and the mixing amount of the shell chips is coarse in the concrete blend. Ri 20 to 60% der by volume to aggregate, grain size grain size 5mm following content in the distribution of the shell tip is characterized by a 30 to 50%.

According to this shelled concrete, the shell chip is replaced with a portion of the coarse aggregate of the concrete and mixed at a volume ratio of 20 to 60% with respect to the coarse aggregate in the concrete composition. Realize shelled concrete with a good balance between recycling rate, cost and quality.

  In the shell-concrete concrete, the shell chip preferably has a particle size range of 20 mm or less. In the particle size distribution of the shell chip, it is preferable that the content of the particle size of 5 mm or less is 30 to 50%. Moreover, it is preferable that the content rate of a fine particle part (0.075 mm or less) is 5% or less in the particle size distribution of the said shell chip.

The method for producing a shell-containing concrete according to the present invention includes mixing a shell chip obtained by crushing shells such as scallops and oysters with a part of the coarse aggregate , and mixing the mixture with the coarse aggregate in the concrete mixture. The volume ratio is 20 to 60%, and the content ratio of the particle size of 5 mm or less in the particle size distribution of the shell chip is 30 to 50% .

According to this method for producing concrete with shells, the shell chip is replaced with a part of the coarse aggregate of concrete and mixed at a volume ratio of 20 to 60% with respect to the coarse aggregate in the concrete composition. Produce shelled concrete with a good balance between recycling rate, cost and quality.

  In the concrete production method, the particle size range of the shell chip is preferably 20 mm or less. In the particle size distribution of the shell chip, it is preferable that the content ratio of the particle size of 5 mm or less is 30 to 50%. In the particle size distribution of the shell chip, the content of fine particles (0.075 mm or less) is preferably 5% or less.

  According to the concrete with shells and the method for producing the same according to the present invention, concrete with shells having a good balance between shell recycling rate, cost, and quality can be realized.

Hereinafter, the best mode for carrying out the present invention will be described. The concrete with shells according to the present embodiment is obtained by using a shell chip as shown in FIG. 1 (b) obtained by crushing a scallop shell as shown in FIG. 1 (a) with a crusher so that the particle size is 20 mm or less. It replaces with a part of aggregate and mixes, and the mixing amount of this shell chip | tip is 20 to 60% by volume ratio with respect to the coarse aggregate in a general concrete mixing | blending.

  In addition, oyster shells can be used other than scallops, and scallop shells and oyster shells are relatively large as industrial wastes in aquatic processing, so that recycling of industrial wastes can be achieved effectively.

  Concrete is a mixture of coarse aggregates such as cement and crushed stone, fine aggregates such as sand and water, etc. at a predetermined ratio. A description will be given of a decrease in strength when the mixing ratio (volume ratio) at the time of mixing is changed with reference to FIG.

In addition, the above-mentioned concrete mix is concrete used for a general structure and has a design standard strength of 18 to 30 N / mm ² and a concrete for producing a slump of 8 to 18 cm. The concrete containing shells is a concrete containing shells in which a part of the coarse aggregate is replaced with shell chips within a predetermined volume ratio in such a concrete mixture.

FIG. 2 is a graph showing the strength reduction rate of concrete obtained by replacing the shell chips obtained from the scallop shell and the oyster shell in this embodiment with a part of the coarse aggregate and mixing them.

In FIG. 2, scallop shells and oyster shells are crushed to a particle size of 20 mm or less , replaced with a portion of coarse aggregate , and mixed with shelled concrete and coarse bone. Normal concrete without shell chips is obtained under the same conditions except for the mixing of shell chips, and the compressive strength of concrete with shells is expressed as a percentage of the compressive strength of normal concrete without shell chips in coarse aggregate. Show.

As can be seen from Fig. 2, the concrete with shells mixed by replacing shell chips with a part of coarse aggregate tends to decrease in strength as the mixing ratio of shell chips increases for both scallops and oysters. It can be seen that if the mixing ratio with respect to the normal coarse aggregate is 60% by volume, the necessary and sufficient strength can be obtained.

  Further, if the mixing ratio of shell chips to ordinary coarse aggregate is 20% by volume, shells such as scallops and oysters will be used in a considerable amount, and scallops and oysters that are industrial waste. Shells can be efficiently recycled, and the shell recycling rate is increased.

  In addition, scallops and oyster shells can be used if they are roughly crushed so as to have a particle size of 20 mm or less, and it is not necessary to crush them finely, so that the cost does not increase.

As described above, according to the concrete with shells of the present embodiment, in the concrete blending for producing concrete having a design standard strength of 18 to 30 N / mm ² and a slump of 8 to 18 cm, Even if part of the coarse aggregate is replaced with shell chips up to about 60% (volume ratio), there is no problem in the quality of the concrete. In this way, necessary and sufficient quality (strength) can be obtained while maintaining the recycling rate of the shells that are waste to a considerable degree, and the cost is not increased. Therefore, it is possible to realize shelled concrete having a good balance between the shell recycling rate, cost, and quality.

  Further, in the shell-containing concrete according to the present embodiment, the particle size range of the shell chip is 20 mm or less, and the content of the particle size of 5 mm or less in the particle size distribution of the shell chip is set to 30 to 50%, which is favorable. A slump can be obtained, good workability can be obtained, and a predetermined strength can also be satisfied. Moreover, a more favorable slump can be obtained by setting the content of fine particles (0.075 mm or less) to 5% or less in the particle size distribution of the shell chip.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a present Example.

  The concrete blending table in Examples 1 to 4 is shown in the following Table 1, and the particle size accumulation curves of scallops 1, 2, and 3 used in Examples 1 to 4 as shown in Table 1 are shown in FIG. Scallops 1, 2, and 3 in Table 1 have different particle size distributions, and their particle size accumulation curves are different as shown in FIG.

  The particle size accumulation curve in FIG. 3 is a curve representing the result (particle size distribution state) obtained by particle size analysis by a particle sieving test in terms of the percentage of particles smaller than a certain particle size and the particle size (logarithm). It was obtained according to the “Soil Grain Size Testing Method” (JGS 0131-2000) of the Geotechnical Society standard.

  As shown in FIG. 3, scallops 1 to 3 each have a maximum particle size of 20 mm, but the content of the particle size of 5 mm or less is 31% for scallop 1, 43% for scallop 2, and 46% for scallop 3. .

  The content of fine particles having a particle size of 0.075 mm or less was 1.4% for scallop 1, 0.65% for scallop 2, and 2.43% for scallop 3.

  Each of the scallops 1, 2 and 3 has a particle size accumulation curve having a finer particle content than the JSCE standard particle size indicated by the broken line in FIG.

Slump test, air amount and compressive strength test for each concrete of Examples 1 to 4 and Comparative Example obtained by replacing the scallops 1, 2, and 3 with a part of coarse aggregate as shown in Table 1 The results are shown in Table 2 below. The slump test was conducted in accordance with JIS A 1101-1998, the compressive strength test was conducted in accordance with JIS A 1108-1999, and the air amount test was conducted in accordance with JIS A 1128.

  When the results of Examples 1, 3, and 4 with a mixing ratio of 60% were compared with the ordinary concrete of the comparative example, the compressive strength decreased because scallops were mixed, but it was found that the necessary and sufficient strength was obtained. In addition, there is no significant difference in strength due to the difference between scallops 1, 2, and 3.

  On the other hand, the slump increases in the order of Examples 3, 4 and 1, and Example 3 is the value closest to ordinary concrete. In addition, it is easier to obtain a predetermined slump when the content is 5 mm or less, but if there are too many fine particles of 0.075 mm or less, the slump tends to be small.

  Next, comparing Example 1 with a scallop 1 mixing ratio of 60% and Example 2 with 40% mixing, Example 2 with a mixing ratio of 40% has a lower strength reduction ratio, but slump is more than ordinary concrete. Is also getting bigger.

As described above, according to the present embodiment, when the shell chip is replaced with a part of coarse aggregate and mixed with concrete, the strength decreases according to the mixing ratio, but the volume ratio is up to about 60%. Necessary and sufficient strength can be obtained.

  Moreover, a favorable slump can be obtained by setting the particle diameter of the shells to be mixed to a maximum of 20 mm and adjusting the content of the particle diameter of 5 mm or less to 30 to 50%. Furthermore, in addition to the above conditions, a more favorable slump can be obtained by suppressing the content of fine particles having a particle size of 0.075 mm or less to 5% or less.

As described above, the best mode for carrying out the present invention has been described. However, the present invention is not limited to these, and various modifications are possible within the scope of the technical idea of the present invention. For example, in the present embodiment, scallops and oysters are listed as shells that can be mixed with a part of the coarse aggregate of concrete, but the present invention is not limited to scallops and oysters, and other shells. Other shells may be mixed with scallop or oyster shells.

Moreover, in this Embodiment and an Example, although the shell chip mixed by replacing with a part of coarse aggregate in concrete has a particle size accumulation curve like FIG. 3, a particle size range is 20 mm or less. The particle size does not include those having a particle size of 20 mm or more. For example, the particle size (opening of the sieve mesh) when the percentage of passage in FIG. 3 is 100% may exceed 20 mm. It may be included to some extent within the range that can be obtained.

It is a figure (a) which shows the external appearance photograph of the scallop shell which can be utilized for this Embodiment, and the figure (b) which shows the external appearance photograph of the scallop shell chip crushed to a particle size of 20 mm or less. It is a graph which shows the strength decreasing rate of the concrete obtained by replacing the shell chip | tip obtained from the scallop shell and the oyster shell in this Embodiment with some coarse aggregates , and mixing them. It is a graph which shows each particle size accumulation curve of the scallops 1, 2, and 3 used for Examples 1 to 4.

Claims (6)

Shell chips made by crushing shells such as scallops and oysters are mixed with a part of the coarse aggregate of concrete,
Ri 20 to 60% der by volume mixture weight relative coarse aggregate in the concrete formulation of the shell tip,
A concrete with shells, wherein the content of particles having a particle size of 5 mm or less is 30 to 50% in the particle size distribution of the shell chips .   The concrete with shells according to claim 1, wherein the shell chip has a particle size of 20 mm or less. The concrete with shells according to claim 1 or 2 , wherein the content of fine particles (0.075 mm or less) in the particle size distribution of the shell chips is 5% or less. Replace the scallop and oyster shell shell chips with concrete with a part of the coarse aggregate , mix,
The mixing amount of the shell chip is 20 to 60% by volume with respect to the coarse aggregate in the concrete blend ,
A method for producing a shell-containing concrete, wherein a content ratio of a particle size of 5 mm or less in the particle size distribution of the shell chip is 30 to 50% . The method for producing concrete with shells according to claim 4 , wherein the shell chip has a particle size of 20 mm or less. The method for producing concrete with shells according to claim 4 or 5 , wherein the content of fine particles (0.075 mm or less) in the particle size distribution of the shell chips is 5% or less.