JP4640735B2 - Recycled concrete and method for producing recycled concrete - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to recycled concrete obtained by recycling concrete lumps discharged as construction by-products and a method for producing recycled concrete.
[0002]
[Prior art]
As a construction by-product, the amount of concrete lumps generated due to the dismantling of concrete structures is the largest. In the future, it is expected that the amount of concrete lumps discharged from the structure will increase with the aging of the structure.
Therefore, the reuse of concrete is required from the standpoint of saving resources and reducing environmental burden in building materials.
[0003]
[Problems to be solved by the invention]
However, concrete lumps are mainly limited to use as roadbed materials, and the reuse rate is currently as low as about 65%.
In addition, in order to meet the quality standards that have been set for recycled aggregate concrete, it has been subjected to advanced processing such as crushing, sorting (foreign matter removal), particle size adjustment, and moisture content management. Although research on the technology for regeneration processing has been conducted, secondary processing and tertiary processing are required, and there are problems in terms of labor and cost.
In view of the above, there is a demand for a more effective recycling method that has a high reuse rate and does not require a high level of processing with respect to the concrete blocks discharged from the concrete structure.
[0004]
In view of the above circumstances, the object of the present invention is more effective as recycled concrete having high strength and excellent durability without subjecting the concrete mass discharged along with the demolition of the concrete structure to the concrete mass. To be reusable.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the invention described in claim 1 is, for example, as shown in FIG. 1, between a large number of concrete blocks 2 obtained by breaking an existing concrete structure and the large number of concrete blocks. Filled concrete 3 which is filled and contains coarse aggregate The particle size of the concrete block is 20 mm or more It is characterized by that.
[0006]
In the recycled concrete according to claim 1, since it comprises the large number of concrete lumps and the filled concrete filled between the many concrete lumps, the concrete lumps can be reused as recycled concrete, Aggregates are contained not only in concrete lumps but also in filled concrete between concrete lumps, so that the overall aggregate has coarse aggregates and has uniform properties. it can.
Therefore, when recycling a large number of concrete lumps obtained by breaking existing concrete structures, for example, concrete lumps discharged with the dismantling of concrete structures, it is necessary to apply advanced treatment to make concrete aggregates. It can be easily reused, saving resources in construction materials and reducing the environmental load. Furthermore, since the filled concrete containing coarse aggregate is filled between a large number of concrete blocks, the compression strength of the entire recycled concrete can be increased as compared with the case where mortar is filled. Therefore, compared with the case where mortar is used as the filler, the durability is improved and the (compression) strength is increased.
In addition, when building re-concrete using concrete lumps generated locally, there is no need to consider the disposal cost of the concrete lumps, and the cost of constructing the structure is based on ordinary ready-mixed concrete (green concrete). It is cheaper than
[0007]
The invention according to claim 2 is the recycled concrete according to claim 1, for example, as shown in FIG.
The concrete block 2 has a particle size of about 20 mm or more and about 200 mm or less.
[0008]
In the recycled concrete according to claim 2, the same effect as in claim 1 can be obtained, and the particle size of the concrete lump is about 20 mm or more and about 200 mm or less. The filling concrete is uniformly filled between the two, and the variation of the concrete block in the recycled concrete is reduced. Therefore, it is possible to obtain a suitable recycled concrete by making the entire compressive strength substantially uniform.
That is, if the particle size of the concrete block is smaller than about 20 mm, the concrete block itself may be smaller than the coarse aggregate in the concrete block, and if the particle size is larger than about 200 mm, the concrete block There is a great variation in the compressive strength of recycled concrete using The particle size of the concrete block is preferably about 20 mm or more and less than about 100 mm, more preferably about 25 mm to 80 mm. When the particle size is about 20 mm or more and less than about 100 mm, the compression strength is more stable than when the particle size is about 20 mm or more and about 200 mm or less, and when the particle size is about 25 mm to 80 mm, the compression strength is more stable and stable. The compressive strength of the entire concrete can be made uniform.
[0009]
Invention of Claim 3 is the manufacturing method of the recycled concrete which manufactures the recycled concrete of Claim 1 or 2, Comprising: As shown, for example in FIG.
A concrete charging step of charging the filled concrete containing coarse aggregate into the recycled concrete molding form 5;
A concrete lump charging step of charging the concrete lump 2 into a mold into which the filled concrete 3 has been charged;
A vibration step of vibrating the concrete block and the filled concrete in the mold is provided.
[0010]
In the method for producing recycled concrete according to claim 3, the filled concrete is thrown into a form for molding recycled concrete in the concrete charging step, and the concrete filled into the concrete block is charged in the concrete block charging step. The concrete lump and the filled concrete in the mold are vibrated in the vibration step, and the vibrated concrete lump and the filled concrete are mixed and compacted. The reclaimed concrete described can be produced.
That is, high-quality recycled concrete can be easily manufactured through the filling concrete charging step, the concrete lump charging step, and the vibration step, and unlike the conventional case, high-grade processing is not performed when the concrete lump is reused.
[0011]
The invention according to claim 4 is the method for producing recycled concrete according to claim 3, for example, as shown in FIG.
The recycled concrete to be manufactured is constructed by being divided into a plurality of layers, and is formed by sequentially repeating the filling concrete charging step, the concrete lump charging step, and the vibration step from the lower layer.
[0012]
In the method for producing recycled concrete according to claim 4, the same effect as that of the invention according to claim 3 can be obtained, and the recycled concrete to be produced is sequentially filled with the filled concrete from the lower layer, Since the concrete lump charging step and the vibration step are repeated and compacted for each layer, the concrete lump, the filled concrete, and the concrete lump, filled concrete and Coarse aggregates contained in these are arranged without variation as a whole, and recycled concrete having a suitable high launch height can be produced.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of recycled concrete and a method for producing recycled concrete according to the present invention will be described below with reference to FIGS.
First, the structure of the recycled concrete which concerns on this invention is demonstrated using FIG.
A recycled concrete 1 according to the present invention shown in FIG. 1 includes a large number of concrete blocks 2 obtained by breaking an existing concrete structure, and is filled between the large number of concrete blocks 2 and includes coarse aggregate. It consists of filled concrete 3.
[0014]
The particle size of the concrete block 2 is about 20 mm to 200 mm (about 20 mm to about 200 mm), preferably about 20 mm to about 100 mm, more preferably about 25 mm to about 80 mm. The resulting demolished concrete is crushed with a concrete crusher or the like. By producing recycled concrete together with the filled concrete 3 using the concrete block 2 of this numerical size, the variation in strength of the recycled concrete itself is suppressed.
The filled concrete 3 contains coarse aggregates such as gravel and crushed stone, and is filled between a large number of concrete blocks 2.
[0015]
According to the recycled concrete 1, the concrete block 2 obtained by breaking the existing concrete block structure can be reused as the recycled concrete 1, and the coarse aggregate is not only between the concrete block 2 but also between the concrete blocks 2. Since it is contained also in the filling concrete 3, the recycled concrete 1 is in a state having a coarse aggregate as a whole. In addition to this, since the concrete lump 2 has a particle size of about 20 mm to 80 mm, in the recycled concrete 1, the concrete lump 2 and the filled concrete 3 containing coarse aggregate are arranged without variation, and per unit of these. The ratio becomes substantially uniform, and the recycled concrete 1 has properties such as compressive strength and the like that do not vary as a whole.
Therefore, when reusing a large number of concrete lumps discharged due to the dismantling of existing concrete structures, unlike the conventional case, there is no need to apply advanced processing to aggregate for concrete, and the concrete lumps can be easily recycled. It can be used to produce recycled concrete having good properties, and can save resources and reduce environmental load in construction materials. In addition, the cost of constructing the structure is lower when the recycled concrete is manufactured using the concrete lump generated locally, compared with the case of manufacturing using ordinary ready-mixed concrete (green concrete).
[0016]
Next, the manufacturing method of the said recycled concrete is demonstrated.
In the method for producing recycled concrete 1 having the above-described configuration, a concrete charging process in which a recycled concrete molding form is prepared and concrete containing coarse aggregate is put into the recycled concrete molding mold, and the concrete block A concrete lump loading step of loading the concrete into the mold into which the concrete has been charged, and a vibration step of vibrating the concrete lump and the concrete in the mold. In addition, the recycled concrete 1 of this embodiment is manufactured by dividing into a plurality of layers.
This will be described with reference to FIG.
FIG. 2 is a diagram showing schematic steps of the method for producing recycled concrete according to the present invention in the order of (a) to (d).
[0017]
First, as shown to Fig.2 (a), the filling concrete 3 is thrown in in the recycled concrete shaping | molding form 5 for shape | molding recycled concrete (concrete throwing process). At this time, the mold 5 is formed according to the shape of the recycled concrete 1 to be manufactured. In addition, the filled concrete 3 is fed into a mold 5 from a mixer truck or the like through a throwing portion such as a flange, and the amount of filled concrete 3 to be fed is divided into a plurality of layers of the recycled concrete 1 to be produced. The amount is required for one layer.
Next, as shown in FIG. 2 (b), the concrete block 2 is put into the mold 5 from above the filled concrete 3 put into the mold 5 through a conveying means such as a belt conveyor. It is arranged (buried) in the filled concrete 3 in the frame 5 (concrete lump charging step). The input amount of the concrete block 2 at this time is an amount necessary for one layer when the recycled concrete 1 to be manufactured is divided into a plurality of layers, similarly to the input amount of the filled concrete 3. Moreover, you may perform surface washing | cleaning and a water absorption process to the concrete lump 2 thrown in. Surface cleaning / water absorption treatment means that after the surface of the concrete block 2 is washed with water, the surface that has been immersed in water for a predetermined time, for example, 24 hours or more, is taken out, the surface is dried, and the surface is dried (the surface is dried). State).
[0018]
Then, as shown in FIG. 2 (c), the vibrator 7 is placed in the recycled concrete molding form 5, and the filled concrete 3 and the concrete block 2 in the form 5 are vibrated and compacted.
At this time, the filled concrete 3 is filled between the concrete blocks 2, and the coarse aggregate of the filled concrete 3 is uniformly arranged between each of the many concrete blocks 2 in the mold 5. As a result, a recycled concrete layer having a uniform compressive strength without variation is formed. In addition, after the compaction process is finished, the vibrator 7 is removed from the filled concrete 3 and the concrete block 2 in the mold 5.
Then, as shown in FIG. 2 (d), recycled concrete is formed in order from the lower layer by repeating filling concrete charging, concrete lump charging, and vibration steps. That is, in order to construct the upper layer part of the recycled concrete layer from the recycled concrete layer constructed by previously filling the concrete and the concrete block, concrete containing coarse aggregate is formed in the same manner as in the previous method. After putting in the reclaimed concrete molding form, and then putting the concrete block into the formwork in which the concrete is put, the vibrator 7 is inserted again into the formwork, and the concrete block and concrete in the formwork are inserted. Vibrate and tighten. This is repeated until the predetermined launch height is reached, and the recycled concrete 1 is formed in order from the lower layer.
[0019]
According to the above-mentioned recycled concrete manufacturing method, high-quality recycled concrete can be easily manufactured through the concrete charging process, the concrete lump charging process and the vibration process. Will not be applied.
In addition, the recycled concrete 1 to be manufactured is formed by repeating the concrete charging step, the concrete lump charging step, and the vibration step from the lower layer sequentially and compacting each layer, so that it is constructed with the concrete lump and concrete. Even if the launch height of recycled concrete is increased, the concrete lump, concrete, and coarse aggregate contained in them are arranged without variation throughout, and a suitable launch height with high durability and improved compressive strength. High recycled concrete can be manufactured.
[0020]
The recycled concrete 1 is configured by using a filled concrete 3 containing coarse aggregate as a filler to be filled between a large number of concrete blocks 2.
Below, the comparison between the recycled concrete according to the present invention and the recycled concrete in which filled mortar is filled between a large number of concrete blocks will be described based on the data of each experiment conducted on the recycled concrete.
[0021]
First, the influence on the compressive strength of recycled concrete due to the difference in the size of the concrete block 2 will be described with reference to FIG.
FIG. 3 is a diagram for explaining variation in compressive strength in recycled concrete having concrete lumps of different sizes (particle size of about 25 mm to 80 mm and about 100 mm to 200 mm), and (a) shows concrete lumps of different particle sizes. The figure which compared the compressive strength of the core extract | collected from arbitrary positions, respectively from the provided recycled concrete, (b) shows the perspective view of the recycled concrete block containing the concrete lump with a particle size of about 25 mm-80 mm, and a core extraction position A cross-sectional view taken along line AA of the block, (c) is a plan view showing a core collection position in a 900 × 900 × 900 recycled concrete block containing a concrete block having a particle size of about 100 to 200 mm, and a cutting position of the collection core It is a perspective view of the core which shows.
[0022]
Two types of concrete blocks having a particle size of about 25 mm to 80 mm and a particle size of about 100 mm to 200 mm are used. Recycled concrete blocks of 600 × 600 × 600 mm (see FIG. 3B) and reclaimed concrete of 900 × 900 × 900 mm, respectively. A block (see FIG. 3 (c)) is prepared, and a core is collected from a predetermined location shown in FIG. 3 (a) (see FIGS. 3 (b) and 3 (c)). The effect on strength characteristics was investigated. Each recycled concrete block has a water-cement ratio of 55% and a unit coarse aggregate amount of 290 (l / mm ^Three These blocks were manufactured by the post-packed concrete method. The post-packed concrete construction method is a method in which after filling concrete into a mold for molding recycled concrete, the concrete chunk is poured into the mold from above the filled concrete. Is the same.
[0023]
Each of the collected cores from the recycled concrete block has a length of 600 mm in a vertical direction from a predetermined location (location indicated by reference numerals 1 to 4 shown in the AA sectional view of FIG. X After collecting a cylindrical body having a bottom surface of Φ150 mm, the cylindrical body is vertically cut at a length of 300 mm (see FIG. 3C) and divided into two parts (Φ150 × 300 mm / piece).
Each of the sampling cores is provided with Nos. 1 to 4 corresponding to the locations of reference numerals 1 to 4 and a reference numeral indicating one of the upper and lower portions thereof.
And the compressive strength was measured for the collection cores collected from each recycled concrete block at the age of 28 days (FIG. 3 (a)).
As shown in FIG. 3 (a), recycled concrete using a concrete lump having a particle size of about 25 mm to 80 mm has an average compression degree of the sampled core of 30.3 (N / mm). ² ), And the coefficient of variation showed a value of 2.9%. Those using a particle size of about 100 mm to 200 mm have an average compressive strength of 28.9 (N / mm ² ), The coefficient of variation was 6.4%. For comparison, recycled concrete using a concrete block having a particle size of about 25 to 80 mm has a high compressive strength, and variation due to the core collection position is also small.
Coarse aggregates in concrete are often used with a particle size of 20 mm. For this reason, the minimum value of the particle size of the concrete block is 20 mm.
In addition, if the particle size of the concrete block is about 200 mm or less, it becomes a recycled concrete having excellent durability and high compressive strength. However, as shown in FIG. 3, the particle size of less than about 100 mm is about 100 mm or more. The variation is less than the compressive strength of recycled concrete using a concrete block.
Therefore, it is desirable that the concrete lump has a particle size of about 20 mm or more and less than about 100 mm (in the figure, about 25 mm or more and about 80 mm or less). The concrete lump has a particle size within this range and filled concrete. Recycled concrete can obtain a stable compressive strength without variation.
[0024]
FIG. 4 is a diagram showing the compressive strength at 7, 28, and 91 days of age for recycled concrete and fillers using various fillers having different unit coarse aggregate amounts. In the figure, the unit coarse aggregate amount = g. In FIG. 4, the unit coarse aggregate amount is 0 (l / m ^Three ), In other words, the mortar is “-●-”, the unit coarse aggregate amount is 0 (l / m) ^Three Recycled concrete using the filler of (-) is shown by the graph “− ○ −”. Moreover, the unit coarse aggregate amount 230 (l / m ^Three ) As a filler, “− ▲ −”, unit coarse aggregate amount 230 (l / m) ^Three Recycled concrete using the filler of ()) is shown by the graph “−Δ−”. Furthermore, the unit coarse aggregate amount 290 (l / m ^Three ) Is indicated by a graph of “− ■ −”, and the unit coarse aggregate amount 290 (l / m) ^Three ) Recycled concrete using fillers is indicated by “-□-”, and the unit coarse aggregate amount 350 (l / m) ^Three ) In the graph of “-◆-”, the unit coarse aggregate amount 350 (l / m ^Three Recycled concrete using the filler of ()) is indicated by the graph “− ◇ −”.
As shown in FIG. 4, the unit coarse aggregate amount (g) 0 (l / m ^Three ), That is, the compressive strength of the mortar (-●-) at the age of 7 days is about 22 (N / mm). ² ), Recycled concrete (-○-) using mortar has a compressive strength of about 11 (N / mm) ² ). The unit coarse aggregate amount 230, 290, 350 (l / m ^Three Similarly, the compressive strength of recycled concrete using the filler (filled concrete) is lower than the compressive strength of the filler (filled concrete) alone.
[0025]
In addition, the compressive strength of recycled concrete at any age of 7 days, 28 days, and 91 days has a unit coarse aggregate amount of 0 (l / m ^Three ) Recycled concrete using filled concrete containing coarse aggregate has higher compressive strength than recycled concrete using mortar. For example, at a material age of 7 days, the compressive strength of recycled concrete using mortar is about 11 (N / mm ² ), While the unit coarse aggregate amount is 230, 290, 350 (l / m) ^Three ), That is, the compressive strength of recycled concrete using filled concrete is about 14, 16, 18 (N / mm), respectively. ² ). At the age of 28 days, the compressive strength of recycled concrete using mortar (g = 0) is about 17 (N / mm). ² ), While the unit coarse aggregate amount is 230, 290, 350 (l / m) ^Three ), That is, the compressive strength of recycled concrete using filled concrete is about 22, 26, 27 (N / mm), respectively. ² ). Furthermore, even at a material age of 91 days, the compressive strength of recycled concrete using mortar is about 22 (N / mm ² ), While the unit coarse aggregate amount is 230, 290, 350 (l / m) ^Three ) With a compressive strength of recycled concrete using filler of about 28, 31, 32 (N / mm), respectively ² ). In this way, recycled concrete using filled concrete containing coarse aggregate has a higher compressive strength than that using mortar (filled mortar) as the filler, for example, 20 (N / Mm ² ) The above is demonstrated, and the compression strength is increased.
[0026]
Here, the correlation between the unit coarse aggregate volume of the filler and the compressive strength of the recycled concrete at the age of 28 days is shown in FIG. In FIG. 5, the coarse aggregate contained is 0 (l / m) at the left end shown by the graph of ●. ^Three ) And the compressive strength of the mortar is 45 (N / mm ² ). This coarse aggregate amount is 0 (l / m ^Three ) Mortar is used as a filler, and the compression strength (represented by a graph) of recycled concrete formed with concrete blocks is about 18 (N / mm ² ). Then, when coarse aggregate is added to the filler (= filled concrete) and the unit coarse aggregate volume of the filler is increased, the compressive strength of the filler decreases accordingly. For example, the unit coarse aggregate volume 100 (l / m ^Three ) Is about 41 (N / mm) ² ), Unit coarse aggregate volume 200 (l / m) ^Three ) Is about 38 (N / mm) ² ), Unit coarse aggregate volume 350 (l / m) ^Three ) Is about 34 (N / mm) ² )
[0027]
On the other hand, the recycled concrete shown by the graph of (circle) becomes large in compressive strength with the increase in a unit coarse aggregate volume. For example, the unit coarse aggregate volume of the filler is 100 (l / m ^Three ), The compressive strength of recycled concrete is 20 (N / mm) ² ), Unit coarse aggregate volume of filler is 200 (l / m) ^Three ) The compression strength of recycled concrete is 23 (N / mm) ² ), The unit coarse aggregate volume of the filler is 350 (l / m) ^Three ), The compression strength of recycled concrete is about 26 (N / mm) ² ).
The compressive strength ratio between the filler and recycled concrete is such that the unit coarse aggregate amount is 0,230,290,350 (l / m ^Three ) Was about 0.38, 0.63, 0.75, 0.81 and increased with an increase in the amount of unit coarse aggregate. Therefore, the use of filled concrete as a filler in recycled concrete using a concrete block can improve the compressive strength as compared with the case of using mortar as the filler. Regarding the unit coarse aggregate volume of recycled concrete, the unit volume mass of recycled concrete using filled concrete is 2.32 (t / m ^Three ) And filled mortar (2.23 (t / m ^Three )), It is preferable to use filled concrete as a filler when recycled concrete is applied to a solidified block or the like.
The unit coarse aggregate amount of the filled concrete is at least 0 to 350 (l / m ^Three If the unit coarse aggregate amount is increased within the range of), the compressive strength of the recycled concrete using the filled concrete increases with the increase of the unit coarse aggregate amount. Therefore, by increasing the unit coarse aggregate amount in the filled concrete within the range of the above unit coarse aggregate amount, the compressive strength of the recycled concrete using the filled concrete whose unit coarse aggregate amount is increased is increased. can do. Therefore, the compressive strength of recycled concrete can be adjusted by increasing / decreasing the unit coarse aggregate amount of the filled concrete. The unit coarse aggregate amount is 350 (l / m ^Three ), The compressive strength of recycled concrete is likely to increase as the unit coarse aggregate amount increases, and the unit coarse aggregate amount is 350 (l / m). ^Three ) The compressive strength of recycled concrete can be adjusted even if it is larger.
[0028]
Fig. 6 shows the results of a freeze-thaw resistance test of recycled concrete when using different fillers, and shows the correlation between the number of cycles and the relative kinematic modulus. Fig. 7 shows a constant water cement ratio. It is a figure which shows the drying shrinkage | contraction of the filler (filled concrete and filled mortar) from which the amount of unit coarse aggregates differs, and recycled concrete using the same.
In FIG. 6, “− ● −”, “− ▲ −”, “− ■ −”, and “− ◆ −” are respectively the water cement ratio (indicated by W / C = in the figure) and the unit coarse aggregate amount ( It is a graph of recycled concrete using different filled concrete (indicated by G = in the figure), which are designated as Experiment Nos. 1 to 4, respectively. “− × −” is a graph showing recycled concrete using filled mortar as a filler, which is Experiment No. 5.
[0029]
As shown in Fig. 6, in recycled concrete (No. 5) using filled mortar, when the process of freezing and thawing is performed once, one cycle, fine cracks are generated on the entire surface in 30 cycles. Due to the progress of the cracks, the concrete was peeled off, and the relative dynamic elastic modulus became 60% or less at 180 cycles, and the relative dynamic elasticity could not be measured at 210 cycles.
As recycled concrete using filled concrete, water-cement ratio is 55% and unit coarse aggregate amount is 230 (l / m ^Three ) Filled concrete (No. 4) showed the same result as the filled mortar, and the relative dynamic elastic modulus became 60% or less at 150 cycles, and the relative dynamic elasticity could not be measured at 210 cycles. This is because the unit coarse aggregate amount of the filler in the recycled concrete of Experiment No. 4 is small.
However, when the water cement ratio is 55%, the unit coarse aggregate amount is 290 (l / m ^Three ) Filled concrete (No. 1) has a relative dynamic elastic modulus of 60% or more up to 240 cycles, so increasing the unit coarse aggregate amount of filled concrete only improves the strength characteristics of recycled concrete In addition, the freeze-thaw resistance can be improved. Furthermore, the unit coarse aggregate amount 290 (l / m ^Three ) Recycled concrete (No. 2 and No. 3) using filled concrete with a water-cement ratio of 45% and 35% has a relative kinematic modulus of 90% or more up to 300 cycles, which is good. It has freeze-thaw resistance.
Thus, in a cold district where the recycled concrete is frozen, the unit coarse aggregate amount is 290 (l / m) in the filled concrete. ^Three ) Or more, and the water-cement ratio is preferably 55% or less. Thus, the unit coarse aggregate amount of the filled concrete is 290 (l / m ^Three As described above, when the water cement ratio is 55% or less, the recycled concrete has a high relative kinematic modulus.
[0030]
Next, with reference to FIG. 7, the length change of the recycled concrete at the time of using filling concrete and a filling mortar as a filler filled between many concrete blocks is demonstrated.
In FIG. 7, “− ○ −” is the drying concrete of the previous experiment No. 1, △ is the recycled concrete of the previous experiment No. 4, and “□” is the drying shrinkage of the recycled concrete of the previous experiment No. 5. It is a graph to show. "-●-" is the filled concrete used for the recycled concrete of Experiment No. 1, "▲" is the filled concrete used for the recycled concrete of Experiment No. 4, and "-■-" is the recycled concrete of Experiment No. 5. It is a graph which shows each of the filling mortar used for concrete. As is apparent from this figure, the drying shrinkage decreases as the unit coarse aggregate amount of the filler increases.
Therefore, from the viewpoint of drying shrinkage, it is more effective to use filled concrete as a filler used for recycled concrete than to use filled mortar.
[0031]
In addition, as shown in FIG. 8, when filled concrete is used as a filler for recycled concrete and when filled mortar is used, it can be seen that filled concrete is worn and resistance is improved. .
FIG. 8 shows that the water cement ratio is 55% and the unit coarse aggregate amount is 290 (l / m ^Three ) Is a chart showing the wear coefficient of recycled concrete (experiment No. 1: shown in graph D) and recycled concrete (shown in graph E) using filled mortar with a water-cement ratio of 55%. . The test for examining the abrasion resistance was performed by sandblasting using specimens that were standardly cured until the age of 28 days.
As shown in this figure, recycled concrete D using filled concrete has a slightly smaller wear coefficient and less variation in the wear coefficient than E when filled mortar is used. As a result, it can be seen that the recycled concrete using the filled concrete is improved in wear resistance as well as strength characteristics and freeze-thaw resistance.
Furthermore, although not shown, as a result of examining the mass change rate of fillers (filled concrete and filled mortar) having a constant water-cement ratio and different unit coarse aggregate amounts, and recycled concrete using the filler, the unit coarseness of the filler was determined. The mass change rate decreases as the aggregate amount increases. Thus, in terms of mass change rate, filled concrete is more effective as a filler used in recycled concrete than filled mortar containing no coarse aggregate.
[0032]
Differences between recycled concrete using filled concrete and those using filled mortar are listed below.
Recycled concrete using filled concrete shows better strength characteristics than those using filled mortar, and 20-40 (N / mm ² ) The above compressive strength can be ensured.
With the increase in the amount of unit coarse aggregate of filled concrete, the compressive strength of recycled concrete using this increases.
Recycled concrete using concrete lumps having a particle size of about 25 to 80 mm has a small variation in strength and uniform recycled concrete quality.
Recycled concrete using filled concrete has a large unit coarse aggregate amount, which is advantageous for application to a solidified block or the like as compared with the case of using filled mortar.
Recycled concrete using filled concrete can improve freeze-thaw resistance compared to the case of using filled mortar.
Recycled concrete using filled concrete can reduce drying shrinkage compared to the case of using filled mortar.
Recycled concrete using filled concrete can be worn away and improved in resistance compared to the case of using filled mortar.
[0033]
Moreover, in the recycled concrete 1 which concerns on this invention, the filling concrete containing a coarse aggregate is used instead of the filling mortar which does not contain a coarse aggregate as a filler filled between many concrete blocks. Therefore, it is possible to use a standard product that has been JIS standard for filling concrete in accordance with the compressive strength of the concrete lump or the recycled concrete produced.
On the other hand, when filled mortar is used as the filler, it is necessary to order a mortar blended so as to have a required strength, which is troublesome.
[0034]
The above-mentioned recycled concrete was manufactured by a method (post-packed concrete method) in which after filling concrete into a mold for molding recycled concrete, the concrete lump is poured into the mold from above the filled concrete. Regardless of this, the recycled concrete produced may be produced in any manner as long as it is composed of a large number of concrete blocks and filled concrete containing coarse aggregates. For example, it may be manufactured by a pre-packed method in which a concrete lump is put into a recycled concrete molding form and then filled concrete is put into the form from above the concrete lump.
However, comparing this pre-packed method with the post-packed concrete method, in view of the fact that the filled concrete contains coarse aggregate, after the filled concrete, the method of pouring the concrete block from above the filled concrete However, it is possible to spread over the entire concrete mass into which the filled concrete is charged or to produce a more suitable recycled concrete.
Also with concrete lumps , Including coarse aggregate The recycled concrete may be manufactured by mixing with the filled concrete and then placing it in a form for recycled concrete. Recycled concrete produced in this way can be used as a whole between concrete blocks. Including coarse aggregate Filled concrete is prevalent and suitable.
[0035]
In addition, the recycled concrete 1 may be any object as long as it is composed of a large number of concrete blocks and filled concrete.
For example, it may be used for unreinforced concrete such as a rooting block or caisson lid used for rooting work.
Below, the construction method at the time of using the recycled concrete which concerns on this invention as a solidified block is demonstrated.
[0036]
FIG. 9 and FIG. 10 are construction outline diagrams showing a method for producing a solidified block (recycled concrete) by the method for producing recycled concrete according to the present invention.
The root-clamping block 10 is obtained by breaking a mold 50 for molding a root-carrying block, filling concrete 30 to be put into the mold by the mixer truck 31, and an existing concrete structure. It is roughly composed of a concrete block 20 that is introduced after the concrete 30.
The formwork 50 is installed at a predetermined position where the rooting block 10 is manufactured at the site. In this embodiment, a plurality of the formwork 50 are arranged in a line as shown in FIG.
Further, at the site, a belt conveyor 21 for putting the concrete block 20 into the formwork 50, a hopper 22 for moving the concrete block 20 to the belt conveyor 21, and a backhoe 24 for putting the concrete block 20 into the hopper 22; A concrete crusher 26 for crushing the transported concrete block 20A (before the concrete block 20 is crushed) is installed.
That is, as shown in FIG. 9A, the concrete block 20 </ b> A is carried to the site by a conveying means such as a truck 27. Then, as shown in FIG. 9B, the concrete block 20 </ b> A that has been carried is put into the concrete crusher 26 by the backhoe 28 and pulverized to form a large number of concrete blocks 20. Here, for the sake of convenience, a large number of concrete lumps 20 are crushed and crushed with a glass 200.
[0037]
Each of the crushed concrete blocks 20 has a size of about 25 to 80 mm. After pulverization, the crushed concrete lump 20 is installed in a predetermined place, that is, in the vicinity of a predetermined formwork to be placed (for example, “after pulverization” in FIG. Glass 200 "portion) and washed as shown in FIG. 9 (c). In addition, the concrete lump 20A carried in may be in a state of being pulverized to a particle size of about 25 to 80 mm when the existing structure is demolished. In that case, the trouble of finely pulverizing with the concrete crusher 26 can be saved on site.
[0038]
Next, as shown in FIG. 9 (d), the concrete lump 20 pulverized to a size of about 25 mm to 80 mm is put into the hopper 22 by the backhoe 24 from the glass 200 after pulverization, and the belt conveyor via the hopper 22 21 and is put into the mold 5 from the belt conveyor 21.
The manufacturing method of the root block in this formwork 50 is manufactured similarly to the manufacturing method of the previous recycled concrete 1.
That is, before the concrete lump 20 is thrown into the mold 50, a predetermined amount of filled concrete 30 is thrown into the mold 50 from the mixer truck 31, and the concrete lump 20 is put into the mold 50. It is thrown in from the top of the already filled concrete 30.
And the root block 10 is manufactured by compacting by vibrating with a vibrator (not shown). In addition, this root hardening block 10 is divided and manufactured by the concrete lump 20 and the filling concrete 30 similarly to the recycled concrete 1 mentioned above.
[0039]
Thus, after manufacturing the root hardening block 10 which applied recycled concrete, the root hardening block manufactured adjacent to the manufactured root hardening block 10 is manufactured similarly. This process is repeated to produce solidified blocks arranged in a row.
In this embodiment, the formwork of the root block may be used as it is integrated with the main body, or may be removed after placing the concrete block and the filled concrete.
[0040]
In the above embodiment, the root block is manufactured by dividing the concrete block and the filled concrete into a plurality of layers in the mold, but the present invention is not limited to this. Instead, it may be manufactured by putting packed concrete into a mold and then putting a large number of concrete blocks and compacting them.
Moreover, the apparatus etc. which throw in a concrete lump into a formwork are arbitrary, and it is needless to say that a concrete detailed structure etc. can be changed suitably.
[0041]
【The invention's effect】
As described above, according to the recycled concrete according to the first aspect of the invention, the concrete block can be reused as recycled concrete, and the coarse aggregate is not only a concrete block but also a filled concrete between a large number of concrete blocks. Since it is also contained, it will be in the state which has the coarse aggregate as a whole, and can have the property made uniform. Therefore, when recycling concrete lumps discharged with the dismantling of concrete structures, it is not necessary to use advanced treatment to make concrete aggregates, which can be easily reused, saving construction materials. Resource and environmental load can be reduced. Furthermore, compared to recycled concrete using mortar as a filler filled between the concrete blocks, it has excellent durability and strong compressive strength, and can be raised in several layers to increase the launch height. it can.
[0042]
According to the reclaimed concrete according to claim 2, the same effect as in claim 1 can be obtained, and the particle size of the concrete lump is about 20 mm or more and about 200 mm or less. During this period, the filled concrete is uniformly filled, and there is less variation in the concrete mass in the recycled concrete, and the overall compressive strength can be made substantially uniform.
[0043]
According to the method for producing recycled concrete according to claim 3, the mold in which concrete is thrown into a mold for molding recycled concrete in the concrete charging step, and the concrete block is put into the concrete in the concrete lump charging step. 3. The recycled concrete according to claim 1, wherein the concrete block and the concrete in the mold are vibrated in the vibration step, and the vibrated concrete block and the concrete are mixed and compacted. Can be manufactured.
That is, high-quality recycled concrete can be easily manufactured only through the concrete charging process, the concrete lump charging process, and the vibration process, and unlike the conventional case, high-grade processing is not performed when the concrete lump is reused.
[0044]
In the method for producing reclaimed concrete according to claim 4, the same effect as that of the invention according to claim 3 can be obtained, and the reclaimed concrete to be produced is sequentially added from the lower layer to the concrete charging step, concrete. Since the lump charging step and the vibration step are repeated and compacted for each layer, the concrete lump, concrete and the The included coarse aggregate is arranged without any variation, and a recycled concrete having a suitable high launch height can be manufactured.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of recycled concrete according to the present invention.
FIG. 2 is a schematic process diagram for explaining a process for manufacturing the recycled concrete of FIG. 1;
FIG. 3 is a diagram for explaining the influence on the compressive strength of recycled concrete due to the difference in the size of the concrete block 2;
FIG. 4 is a diagram showing compressive strengths of recycled concrete and fillers using various fillers having different unit coarse aggregate amounts at 7, 28, and 91 days of age.
FIG. 5 is a diagram showing the correlation between the unit coarse aggregate volume of the filler and the compressive strength of the 28-day age of recycled concrete.
FIG. 6 is a diagram showing the results of a freeze-thaw resistance test of recycled concrete when using different fillers.
FIG. 7 is a diagram showing drying shrinkage of fillers (filled concrete and filled mortar) having a constant water cement ratio and different unit coarse aggregate amounts and recycled concrete using the filler.
FIG. 8 is a diagram showing test results comparing the abrasion resistance of recycled concrete using filled concrete and filled mortar as fillers.
FIG. 9 is a diagram showing a schematic process of a manufacturing method of a root hardening block to which recycled concrete according to the present invention is applied.
10 is a top view of a construction site where a process of manufacturing the root block shown in FIG. 6 is performed. FIG.
[Explanation of symbols]
1 Recycled concrete
2,20 concrete block
3,30 Filled concrete
5 Formwork
7 Vibrator
10 Root hardening block (recycled concrete)
50 Formwork for mold-blocking blocks (formwork)

Claims (4)

A number of concrete mass obtained by breaking the existing concrete structures, filled between each other said multiple of concrete mass and, Ri Do and a compacting concrete containing coarse aggregate,
Recycled concrete, wherein the concrete block has a particle size of 20 mm or more .   The recycled concrete according to claim 1, wherein the concrete block has a particle size of about 20 mm or more and about 200 mm or less.   A method for producing recycled concrete according to claim 1 or 2, wherein a concrete charging step of charging a filled concrete containing coarse aggregate into a form for molding recycled concrete; and A method for producing recycled concrete, comprising: a concrete lump charging step for pouring into a formwork in which is placed, and a vibration step for vibrating the concrete lump and the concrete in the formwork.   4. The recycled concrete manufacturing method according to claim 3, wherein the recycled concrete to be manufactured is constructed by being divided into a plurality of layers, and is formed by repeating the concrete charging step, the concrete lump charging step, and the vibration step sequentially from the lower layer. A method for producing recycled concrete.

Images