JP2017056615A - Reutilization method of surplus ready-mixed concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reutilization method of surplus ready-mixed concrete capable of effectively utilizing natural resources by eliminating energy loss and economic burden accompanied with an operation and the like in the treatment and disposal of surplus ready-mixed concrete by a ready-mixed concrete manufacturer.SOLUTION: Surplus ready-mixed concrete such as ready-mixed concrete produced with specific blending in a ready-mixed concrete factory, transported by a dedicated transport vehicle with an agitation unit after production and not unloaded within a time, excess ready-mixed concrete and rejected ready-mixed concrete in confirmation tests of flowability and the like implemented at a site is utilized as the raw material of concrete products by selecting one of the following ways to adjust a water and cement ratio (W/C): adding cement; mixing with the other surplus ready-mixed concrete; and additional mixing with kneading water.SELECTED DRAWING: Figure 1

Description

  Produced in a ready-mixed factory with a specified formulation, transported by a dedicated transporter equipped with a stirring device after manufacture, unloaded in time, unprocessed ready-mixed, surplus ready-mixed, fluidity implemented on site, etc. This is related to the method of reusing surplus ready-mixed concrete, which is raw concrete that failed in the confirmation test.

  In the ready-mixer manufacturer, the processing and disposal of surplus ready-mixed concrete (hereinafter referred to as surplus ready-mixed concrete) is problematic due to energy loss and economic burden associated with these operations. Here, surplus cooked rice is manufactured at a ready-mixed plant at a ready-mixed plant, transported by a dedicated transporter equipped with an agitator after production, and unloaded in time, unfinished cooked food, on-site It is defined as raw concrete that failed in the confirmation test of fluidity conducted.

  JIS ready-mixed concrete (hereinafter referred to as ready-mixed concrete) (JIS A 5308) manufactured at the current ready-mixed factory is manufactured by mixing cement, aggregate (sand and gravel), water, admixture, etc. Refers to the condition from delivery to unloading. The ready-mixer for construction uses JIS, JASS, etc., and determines the usage time, temperature, etc. in consideration of environmental conditions at the construction site.

  However, surplus components such as raw components that were canceled after manufacturing due to user convenience or natural conditions, surplus components after placement, raw components that failed on site inspection, raw components that could not be delivered by the scheduled time, Generally, disposal processing, solid-liquid separation processing, disposal, etc. are performed.

  The cost associated with this is borne by the raw control company. Such surplus kon varies depending on the factory scale and regional differences, but there is also a report of 3 to 4% of the sales volume (symbiotic cooperative association report).

  In addition, natural sand and gravel are used in the preparation of ready-mixed food, and it is mixed in the ready-mixed food at a mass ratio of about 80%. Therefore, the disposal of surplus kon means the same as the disposal of natural resources.

  Most of the surplus raw concrete is brought back to the raw concrete factory and processed into industrial waste. In addition, aggregates classified in the processing process may be reused. However, most of the ready-mix factories manufacture ready-mixed concrete for use in construction. There are few cases where it is effectively used as raw material for raw materials because of the reason that this image gives a bad impression to customers.

  On the other hand, the manufacture of concrete products (precast concrete) is often produced in product factories, and unlike raw concrete for construction, there is no provision for handling until placement. In addition, there are a wide variety of concrete products, and the degree of freedom to use various mixtures and admixtures is greater than that for construction concrete.

  At present, there are cases where concrete blocks and the like are manufactured by placing them in a formwork as a reuse of surplus raw concrete. However, most of the cured products are not used for quality control in the state of raw concrete (before curing) that affects strength quality, and are used for applications that do not cause problems with the structure. Yes.

As a method of manufacturing reclaimed concrete, there are the following patent documents, such as pile head surplus parts removed after casting cast-in-place concrete piles, and it is difficult to use as recycled aggregate. The entire amount of waste concrete mass containing weak concrete part is effectively used as aggregate of recycled concrete.
JP 2006-326906 A

  This Patent Document 1 is a method for producing recycled concrete using raw concrete made of water, cement and aggregate, crushing a plurality of concrete blocks having different strengths, and using the entire amount of the crushed material as the aggregate. Based on the strength required for recycled concrete, the mixing ratio of concrete lumps having different strengths is adjusted, and the total amount of crushed material of these concrete lumps is used as an aggregate.

  The strength of each concrete block is lower than the strength of the cement paste portion of recycled concrete, and the mixing ratio of concrete blocks having different strengths at a certain water-cement ratio and aggregate addition ratio and the strength of recycled concrete Then, the mixing ratio of the concrete blocks having different strengths is determined based on this relationship.

  The above-mentioned patent document 1 regenerates all the fine and coarse particles obtained by crushing and crushing a concrete lump generated when demolishing an existing concrete structure from the viewpoint of effective use of resources. It is proposed to be used as an aggregate of concrete, and is not intended to reuse surplus surplus waste, nor does it bring about an economic effect of reducing the labor of processing waste waste surplus waste.

  The object of the present invention is to eliminate the inconveniences of the conventional example, and to process and dispose of surplus raw material in the raw material manufacturer, thereby losing energy loss and economic burden associated with these operations, etc., and making effective use of natural resources. A method for reusing surplus concrete that can be produced is provided.

  In order to achieve the above object, the present invention is manufactured in a ready-mixed factory at a ready-mixed factory, transported by a dedicated transporter equipped with a stirring device after manufacture, and unloaded in time, Cement is added to surplus raw con that is a raw con that has failed in the confirmation test for fluidity, etc. conducted on site, and is mixed with other surplus raw cond. The gist is to select one of these and adjust the water-cement ratio (W / C) to be used as a raw material for concrete products.

  According to the first to sixth aspects of the present invention, most of the ready-mixed kon used at the construction site is manufactured with a predetermined composition in the ready-mixed factory, and a dedicated agitator (stirrer) is mounted after the manufacture. It is transported with a transport vehicle (raw concrete car), and unloading is carried out within the prescribed time in handling the raw concrete for construction, but the raw concrete that could not be unloaded within this time, surplus raw concrete, on-site Raw kon which failed in the confirmation test such as fluidity carried out is returned to the manufacturing factory and discarded as surplus raw corn as it is, or surplus kon is classified in the factory (solid-liquid separation process), It is processed as industrial waste by volume reduction treatment, etc., aggregates collected after classification are used in our own factory, and used as roadbed materials, but surplus raw concrete is used without such treatment be able to.

  The composition of ready-mixed concrete for construction is different in each construction site, and the surplus ready-mixed concrete is unnecessary concrete in the construction site, and there are cases where the cleaning water of the concrete pump is mixed. In ready-mixed cars, water is added to facilitate subsequent cleaning, so it must be considered different from the concrete composition at the time of shipment.

  In other words, the mix of ready-mixed kon loaded on each live-con vehicle that brings back surplus kon from the site is not stable and must be considered to be all different.

  The present invention measures the water / cement ratio (W / C) of unnecessary surplus concrete that is often disposed of in general, and improves the W / C to meet the required performance of concrete products depending on the application. Therefore, in order to reuse as raw concrete for concrete products, it is a regeneration technology for surplus raw concrete that manufactures raw concrete by adding cement or admixture afterwards. As a result, the quality of the concrete product can be ensured while saving the raw material for the concrete product.

  Aggregate classified in the process of surplus raw concrete may be reused, but many raw concrete factories manufacture raw concrete for construction, and control and reuse according to quality regulations in the production of raw concrete for construction There are few cases where the image of raw kon is used effectively as raw konbu raw material because of the bad impression on customers.

  The present invention is used as a raw material for concrete products (precast concrete), and the manufacture of concrete products (precast concrete) is often produced in product factories. There is no provision for this. In addition, there are a wide variety of concrete products, and the degree of freedom to use various mixtures and admixtures is greater than that for construction concrete.

  At present, there are cases where concrete blocks and the like are manufactured by placing them in a formwork as a reuse of surplus raw concrete. However, most of the cured products are not used for quality control in the state of raw concrete (before curing) that affects strength quality, and are used for applications that do not cause problems with the structure. Yes.

In the present invention according to claim 4, the water cement ratio (W / C) is adjusted by measuring the unit water amount of surplus raw concrete, and the unit water amount (the amount of water contained per 1 m ^{3 of} raw concrete) The gist is to confirm that the water cement ratio (W / C) suitable for strength quality is within the usable range.

  According to the fourth aspect of the present invention, it is known that the strength of concrete is related to the water cement ratio (W / C), and the inverse cement water ratio (C / W) is proportional to the strength in a linear function. Although it is related and is often used for strength estimation, etc., based on such a reliable theory, the range of W / C in terms of quality management is set based on the target strength of concrete products using surplus raw concrete. The surplus raw concrete can be made into a quality that can be used for concrete concrete raw concrete.

As described above, the method for reusing ready-mixed concrete according to the present invention eliminates the energy loss and economic burden associated with these operations, etc., in the processing and disposal of surplus ready-mixed concrete in the ready-mixed manufacturer, and aims to effectively use natural resources. Is something that can be done. Specifically, it has the following effects.
1) Economic effects Earlier, it was stated that 3-4% of the sales volume of ready-mixed food is surplus. The profit and loss of the ready-mix factory is about several percent, while 3 to 4% of surplus ready-mixed can be used as valuable resources, which leads to an improvement in profit and loss. In addition, the expansion of cooperation between ready-mixed concrete factories and product factories can produce concrete products, which leads to cost reduction of concrete products.
2) Environmental effects Effective use of natural resources and energy saving associated with concrete product manufacturing.
3) Effective utilization of surplus raw concrete There are cases where surplus raw concrete is separated and classified and used as raw aggregate or roadbed material. Compared with these effective utilization methods, in the case of the present invention, the labor of classifying surplus raw waste, the loss of energy, and the amount of waste generated are reduced in terms that the surplus raw waste can be used as it is. In addition, the amount of compression is further increased by cooperation with multiple factories.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As a first embodiment of the present invention, a ready-mixed container manufactured in a ready-mixed factory at a ready-mixed factory and transported by a dedicated transporter equipped with a stirring device after manufacture and unloaded in time, surplus As a raw material for concrete products by adjusting the cement-to-water ratio (W / C) by post-adding cement to surplus ready-mixed concrete that has failed in the confirmation test for fluidity, etc. It is what you use.

  In the method for recycling ready-mixed concrete according to the present invention, strength is set mainly by adjusting W / C, and its form is shown in the flow charts of FIGS. Although the 1st form in it is set as the post-addition cement, first, the processing flow of the surplus raw-comb in a general raw-con factory is first demonstrated with reference to FIG.

  When processing surplus cooked rice at a ready-mixed plant, it is added to an agitator of a ready-mixed vehicle with surplus cooked food, and then discharged, solid-liquid separated, and separated into coarse particles and suspended water. Coarse particles are reused as recovered aggregate or RC material (roadbed material) or disposed as waste.

  On the other hand, sludge is agglomerated and reduced in volume with a filter press or the like for industrial waste disposal. Moreover, when solid-liquid separation is not performed, the surplus raw concrete is hardened and disposed of as industrial waste as concrete waste (concrete waste).

  On the other hand, the present invention is manufactured in a ready-mixed factory at a ready-mixed plant, transported by a dedicated transporter equipped with a stirring device after manufacture, and unloaded in time, unprocessed ready-mixed, Adjust the water-cement ratio (W / C) of surplus raw concrete that is unacceptable in the fluidity test conducted at the site, add the cement and water afterwards, and use it as a raw material for concrete products . Further, if necessary, the recycle blending is adjusted by selecting and examining reuse in the flowchart shown in FIG.

Furthermore, the water cement ratio (W / C) is adjusted by measuring the unit water volume of surplus raw concrete, and the water quantity (the amount of water contained per 1 m ^{3 of} raw concrete) matches the strength quality of the concrete product. It is confirmed by confirming that the ratio is within the usable range in terms of the ratio (W / C).

In other words, when using surplus raw concrete for concrete products (precast concrete), in order to adjust the water-cement ratio (W / C), the cement or water content is adjusted, re-kneaded, and is subject to disposal. as a management method of producing the available concrete (refresh concrete) playing the surplus production configuration, to measure the unit water surplus raw Con, the unit water amount (amount of water contained in the fresh concrete 1 m ³ per) are of concrete products After confirming that the water cement ratio (W / C) suitable for strength quality is within the usable range, surplus raw concrete is used as a raw material for concrete products.

  When manufacturing a concrete product using surplus surplus concrete, it can be used even if there are multiple types of surplus surplus concrete. The term “plurality” as used herein refers to the number of surplus raw concrete transportation vehicles (raw concrete vehicles).

  The ready-mixed concrete used at the construction site is transported when the quality and composition of the ready-mixed concrete loaded at the factory shipment is clarified. However, surplus kon may be watered on site. Therefore, it is safer to consider that the unit water volume of the loaded raw concrete differs depending on the raw concrete car.

  Further, surplus raw food containers include raw food containers that have been canceled before being loaded onto a raw food container car at the time of shipment, and raw food containers that have not been made into a predetermined composition due to problems during manufacturing.

  There may be a plurality of surplus cookers shown in FIG. 1, and even if the W / C of each cooker is different, it is confirmed that the W / C converted from the unit amount of water when these are mixed is in a range suitable for the quality. If possible, it is determined that the required performance is satisfied. However, if the starting time of the setting of the ready-mixed concrete that is affected by the hydration of the ready-mixed raw material cement is set to 5 to 6 hours, it is not used as a raw material for the concrete product if there is only one type of surplus ready-made concrete that will pass the starting time. Like that.

  In other words, setting W / C within a range that satisfies the required quality increases the possibility of ensuring strength quality. However, since the quality is not promised after the start time of the live control, such live control is not guaranteed. Do not use. However, since the initial start time varies depending on the influence of the delay agent and the temperature, the initial start time for management is managed as a usable time in consideration of these.

  The unit water amount is measured using a method selected from a method of obtaining a sample by drying, a method of obtaining from a unit volume mass, a method of obtaining electrically, a method of using a reagent, and a method of using radiation. However, in the case of using a plurality of surplus kon, it is less likely to be affected by an error that differs depending on the measurement method when unified to one unit water amount measurement method.

  Concrete products are shipped in a state where a predetermined strength and quality can be ensured. The determination may be made by measuring the strength from a separately prepared specimen for strength measurement at the time of manufacture, or a method of directly measuring the product using a test hammer. The strength determination is obtained from the converted value of the test hammer and the relational expression obtained from the actual strength test.

  Although the case where the amount of unit cement is increased by the post-added cement has been described in the first embodiment, the second embodiment is mixing with other surplus kon. W / C is adjusted by changing the mixing ratio with surplus raw concrete having different W / C.

  Furthermore, you may make it adjust W / C by adding kneading water as 3rd Embodiment. That is, it is a case where moisture is added in the setting of W / C.

  In general, surplus cooked rice is returned to the manufacturer's cooker plant and processed. Therefore, the concrete product manufacturing place will be a ready-mixed factory. However, unlike the concrete product manufacturing factory, the ready-mix factory may not be able to secure a curing place or personnel associated with the concrete product manufacturing, so several ready-mixed factories will manufacture in cooperation.

  For that purpose, it is also necessary to share information on surplus raw kon (W / C, time after kneading, presence / absence of water addition, etc.). In addition, a network that allows the surplus cookers to easily adjust the W / C and the like required for the product to be manufactured is constructed so that these can be used at the participating plant factories.

  FIG. 3 shows an image of information sharing using surplus raw food. Vehicles equipped with surplus raw concrete that want to return to the participating raw concrete factories use the communication line to register information with the central management and provide information to product manufacturers who use surplus raw concrete.

  As a result, the raw concrete truck loaded with surplus raw concrete can be supplied to other users without returning to the manufacturer's factory. In addition, since the manufacturer can obtain the surplus kon corresponding to the required quality of the product from several places and prepare for manufacturing adjustment, the timing that can be used within the pot life is not lost.

  By making such information available not only between ready-mixed factories but also in concrete product factories, it can be supplied as raw materials for more advanced products than concrete products that can be manufactured in ready-mixed factories. Become.

  In concrete product factories, there are many opportunities not only to use advanced bar arrangements and formwork depending on the product application, but also to develop these.

  On the other hand, in the ready-mix factory, the use of surplus cooked rice is only used as a destination, and it is easy to use unfinished products and simple formwork, so the variety of uses is inferior.

  In order to use the surplus concrete as a raw material for the concrete product, a slurry may be added to the surplus raw concrete in FIG.

  In general, when a polymer-based admixture is added later, there are many cases in which high-speed stirring is performed with an agitator mounted on a ready-mixed vehicle.

  However, in the addition of the cement, the mixing efficiency deteriorates if the added amount increases even if the cement is added to the agitator mounted on the ready-mixed vehicle directly with the addition of the cement.

  When re-kneading by adding an additive such as cement to the surplus raw kon, what can be added to the addition target to be slurried is added to the slurry and mixed. FIG. 4 and FIG. 5 show images in the case of adding the slurry to the surplus kon. Although FIG. 5 shows a batch mixer, a continuous mixer may be used.

  When using an existing mixer or a special mixer for re-kneading the surplus kon, if it cannot be put directly into the mixer, supply the surplus kon using a pump, and stir and mix with the object to be mixed .

  Next, the method for calculating W / C of surplus corn will be described in more detail. Fig. 6 is a schematic diagram of the state of raw kon and surplus raw kon at the time of manufacture as showing the basis for calculating W / C of surplus raw kon. Basically, sand, gravel and cement in surplus kon are Remains in the state ratio. The amount that fluctuates is often the amount of water.

  That is, in a general concrete blending setting, the addition ratio of cement and sand / gravel is not extremely changed, and the range of the moisture addition ratio is small. For example, when expressed in terms of moisture content, the amount of change is as small as 7 to 10% and about 3%. In the cement, the adhesive force due to the hydration reaction with the relatively small amount of moisture is integrated with the aggregate and greatly affects the strength. The strong correlation between W / C and strength is the relationship between the extremely small amount of water and the amount of cement, so adjustment of a very small amount of moisture change is important. In addition, it can be said that the strength in blending is set on the basis of the extremely small width W / C.

  That is, in the case of general concrete, the strength can be estimated by setting W / C without knowing the exact volume.

If it demonstrates in FIG. 9, the mixing | blending setting suitable for the required intensity | strength of a concrete product can be performed in the following procedures.
・ Cement of surplus concrete and S / G (fine aggregate and coarse aggregate) remain the same.
Therefore, since W / C is a mass ratio, ΔWwt may be obtained.
-W '/ C is easily obtained by measuring the unit water amount W' of surplus raw concrete.

Next, in order to set the W / C required for the product and to change the W / C of the surplus control unit,
(1) Water is added if the surplus raw food W ′ / C is smaller than the product W / C.
(2) When surplus kon W '/ C is larger than product W / C, cement is added.
(3) In the case of using a plurality of surplus crumbs, W ′ / W of each surplus crumb is obtained to obtain the ratio of the total ΣW ′ of each surplus crumb and ΣC which is a cement mass meter.
(4) The increase / decrease in the W / C of a plurality of surplus corn is adjusted by using the result calculated in (3) and (1) or (2) together.
-When placing in a formwork, since it calculates with a volume, in order to obtain | require a required volume, it is necessary to obtain | require synthetic | combination volume (SIGMA) V.
(5) The increased or decreased A ′ is obtained by a test using an air meter or the like. Or it calculates | requires by actually measuring the wet density (rho) 'of the surplus raw synthetic | combination synthesized. Thereby, the volume V ′ is obtained.
(6) When calculating the ratio of each volume,
Sum of each volume excluding air amount Va ′ Vx = {(Wwt / ρw) + (W / C / ρc) + (Wg / ρg) + (Ws / ρs)}
Sum of each mass for each volume Wx = Wwt + W / C + Wg + Ws
Wet density ρx = Wx / Vx obtained by removing air amount ΔVa ′
The air volume VA ′ is a value obtained by subtracting Vx from the volume V ′ obtained from the actually measured wet density in (5).
VA '= V'-Vx

  The example which mixed the raw concrete from which said 2nd Embodiment differs is demonstrated.

  A compression test was performed by setting the mixing ratio from W / C for different surplus raw kon A and B shown in Table 1 below. In this case, the expression strength target is the quality strength of the concrete product. Since the test result exceeds the expression intensity target, the strength quality is satisfied.

The expression strength target value is called nominal strength in the mix of ready-mixed concrete, and shows the same tendency as the relationship with W / C of surplus concrete, so there is no problem with strength and it can be applied. .
Table 1 below shows the relationship between strength and W / C when different surplus kon after 4 hours of pot life is mixed.


The W / C of surplus kon of A and B is calculated from the unit amount of water.
W + C of A + B is calculated from W / C of A and B.

  FIG. 7 shows the relationship between W / C and compression strength of different surplus corn.

Next, an example of the post-added cement of the first embodiment will be further described.
Table 2 below shows the composition at the time of shipment of ready-mixed concrete.

The unit water amount of surplus raw concrete at the time of shipment shown in Table 2 above was measured by a microwave oven method, and a result of 199.9 kg / m ³ was obtained. From the ratio with the amount of cement in the mixture, W / C = 57.1% is obtained. Here, the blending is determined so that the W / C of the ready-mixed concrete used for the product concrete is 55%.

  Since the freshly cooked kon varies depending on the amount of water added, moisture and sand / gravel may be separated and settled.Therefore, the composition of the surplus kon is not estimated from the wet density. It may be calculated from the wet density while taking into account the state of the raw concrete. In that case, it is preferable to consider the amount of air.

In this example, when converted to moisture 24.9 + W / C shown in Table 2, 193.9 / 350 = 55.4%, and the blending amount per unit volume in this state was determined. At that time, since the fine aggregate S (sand) and coarse aggregate G (gravel) are reduced in volume in the same way as the volume of cement is reduced, the average density (specific gravity) of sand and gravel is shown in Table-2. It is necessary to calculate. Since the density (specific gravity) of cement and water is stable, it can be easily obtained by reverse calculation.
1000- (350 / 3.15) + (175/1) = 713.9L Average density = 1.788 / 713.9 = 2.505

In this example, it was estimated that the wet density of surplus kon decreased due to an increase in moisture, and the volume of cement, sand and gravel decreased accordingly. In other words, each blending amount per 1 m ³ (1000 L) of surplus kon is obtained by calculating backward from the moisture content of surplus kon.

Next, the blending amount for making the concrete product W / C = 55% is obtained by blending cement per 1 m ³ of surplus kon. In this calculation, the cement mass is obtained by calculating backward from the water content, and 363.4 kg / m ³ is obtained. Therefore, W / C = 55% can be set by adding 13.4 kg of the cement shortage.

Table 3 below shows the composition of each ready-mixed state.

  Since Table 3 calculates W / C based on the raw concrete volume, it was assumed that the volume of sand and gravel was reduced by the amount of fresh raw concrete at the time of shipment. On the other hand, the ready-mixed concrete recycled for concrete products calculates the amount of cement from the set W / C and the amount of water, so that the volume of sand and gravel is further reduced in the formulation.

In actual work, since W / C is merely reduced, the cement shortage obtained from Table 3 is simply added and agitated according to the amount of surplus kon.
In the increase / decrease of W / C in the mixing of concrete, when the amount of cement is constant, the mixing is suppressed so that the separation due to the amount of moisture in the ready-mixed corn is less than the volume of the ready-made kon, so the increase / decrease in the amount of moisture is negligible. The amount of cement is large, and the influence of cement adhesive strength on the change in W / C is great.

  As shown in FIG. 8, the smaller the W / C, the greater the strength. At the W / C = 55% of the post-added cement, it is intermediate between the compressive strength results at the time of shipment and the surplus surplus concrete. It can be seen that even after cement addition based on W / C, it can be adequately handled.

  In the case of post-added cement, when re-stirring is performed smoothly by adding cement, it is preferable to add admixtures such as a fluidizing agent and a water reducing agent according to the fourth embodiment. The addition amount of the admixture may be handled in the same manner as general concrete blending.

  When high-strength ready-mixed concrete becomes surplus concrete, add after sand. The W / C of high-strength raw concrete is small compared to other raw concrete, so when using this, it is necessary to adjust by adding moisture.

At that time, increasing the amount of water may affect the bleeding (material separation) and the like, so there are cases where the aggregate needs to be added later. In this embodiment, the aggregate amount was adjusted simultaneously with the addition of water.
(1) Shipped as a blend of high-strength concrete (60-55-20N, air volume 3%).
And compression strength at the age of 28 days, was 72.2N / mm ^2.

(2) About the ready-mixed concrete shipped with the mixing | blending of said Table 4, it returned to the factory as a surplus ready-mixed state in 150kg / m < ³ > hydrated state. (For the amount of water, the test described in the previous section was performed.)
-Since it was found that 150 kg / m ^{3 was} added, the apparent W / C was (170 + 150/532) × 100 = 60%.
・ Volume increased by 0.15 m ³ , and apparent formulation was as follows.
-Material separation occurred in this state. In this state, it is usually a solid-liquid separation process. However, since the material is separated (bleeding) with a large amount of water, it can be reused by adding sand as an admixture without changing W / C. did. In this case, sand was used because it was desired to increase the viscosity and reduce the influence on fluidity by using an admixture such as slag with small particle size. On the contrary, an admixture with a small particle diameter is preferable when it is desired to have viscosity.

(3) A formulation for improving handling (usability) was examined without increasing the viscosity, and sand was added after 300 kg / m ³ .
As a result, the volume increased by 0.114 m ³ (300 kg ÷ ρ2.63 = 0.114), and the apparent composition was as follows.
・ Material separation was eliminated, workability was improved, and handling sufficient for placing was obtained. The slump flow was 51cm and the air volume was 2.4%.
And compression strength at the age of 28 days, was 23.9N / mm ^2.
Thus, in the present invention, other admixtures may be added later instead of sand. However, it must be formulated in consideration of the density of the admixture.

  Since concrete products have different shapes and dimensions, the strength of the concrete itself is generally collected by collecting specimens for compression testing at the time of production of raw concrete, and testing at a specified age. The same method is used for the quality check of the compression strength of the present invention. However, the quality of concrete products must be satisfied at the time of shipment.

  In concrete products, since there is a correlation between the strength of concrete and the hardness of the concrete surface, there is a test hammer (or Schmidt hammer) as a measuring instrument to measure the rebound hardness. Therefore, it can be measured without damaging the product. However, the accuracy is not always stable.

  Therefore, the correlation between the product made from surplus concrete and the value of the compression test was determined and used. FIG. 9 shows the results.

  Moreover, each compressive strength was expressed more than 20% compared with the nominal strength used by the mixing | blending of concrete. As a result, it was determined that the blending correction based on the W / C using surplus raw concrete can be used sufficiently without departing from the strength characteristics of a general concrete blending.

  In addition, in the method of manufacturing concrete using surplus raw concrete, the use can be made possible even when the water cement ratio (W / C) converted from the unit water amount satisfying the requirement of the concrete product is deviated.

  This can increase the amount of surplus corn that can be used for concrete products. However, the concept of pot life and the quality control of products as described in the previous draft shall be the same.

  About surplus kon, unit water quantity is measured based on W / C at the time of shipment, current unit water quantity is obtained, and W / C is converted. Up to this point, the same as in the previous section. Here, even in a state where the required performance is not satisfied, as a possibility of reuse shown in the flowchart of FIG. 2, the post-addition fluidizing agent or the like described above is added. A water reducing agent or the like is used when fluidity at the time of placing is ensured by the structure of the formwork or bar arrangement, the amount of placement, or the like, or when remixing is difficult by blending.

  As a fifth embodiment, fiber addition is performed. This is a case where mixing of fibers (polypropylene fiber, vinylon fiber, steel fiber, etc.) is required for concrete products.

  In the sixth embodiment, an admixture is added. FIG. 10 shows a regenerated blend in which an admixture is added afterwards. The part A in the figure is a surplus raw mix component, and the admixture of the B part is mixed and regenerated into a ready mix for concrete products. As an admixture, slag, calcium carbonate, fly ash, papermaking sludge, ready-mixed sludge and aggregate (aggregates include recycled aggregates such as recycled sand) etc. are mixed to adjust the density and workability etc. Also improve the effective formulation.

  Mixing of fibers and admixtures cannot be solved by W / C alone, so a compounding test may be required in advance. If the compound has already been proven, add fibers and admixtures. In some cases, it is possible to adjust the W / C from the excluded formulation.

  As shown in FIG. 10, it is possible to modify the blending by considering the portion A as a concrete foundation blend and considering the W / C as a reference. Moreover, in such a case, not only W / C but also the fluidity in the raw cooking state may be used as the management value.

It is a flowchart which shows 1st Embodiment of the reuse method of the ready-mixed concrete of this invention. It is a flowchart which shows other embodiment of the reuse method of the ready-mixed concrete of this invention. It is a sharing image figure of surplus raw kon information. It is explanatory drawing of the 1st example in the case of adding a slurry to surplus raw concrete. It is explanatory drawing of the 2nd example in the case of adding a slurry to surplus raw concrete. It is explanatory drawing which shows the calculation basis of W / C of surplus raw control. It is a graph which shows W / C and compression strength of different surplus raw material. It is a graph which shows the compressive strength result which added post-added cement to surplus raw concrete. It is a correlation figure of the compressive strength of concrete using a surplus raw concrete, and a test hammer. It is a conceptual diagram of the reproduction | regeneration mixing | blending using a mixture. It is a flowchart which shows the processing concept of surplus raw material.

  Produced in a ready-mixed factory with a specified formulation, transported by a dedicated transporter equipped with a stirring device after manufacture, unloaded in time, unprocessed ready-mixed, surplus ready-mixed, fluidity implemented on site, etc. This is related to the method of reusing surplus ready-mixed concrete, which is raw concrete that failed in the confirmation test.

  In the ready-mixer manufacturer, the processing and disposal of surplus ready-mixed concrete (hereinafter referred to as surplus ready-mixed concrete) is problematic due to energy loss and economic burden associated with these operations. Here, surplus cooked rice is manufactured at a ready-mixed plant at a ready-mixed plant, transported by a dedicated transporter equipped with an agitator after production, and unloaded in time, unfinished cooked food, on-site It is defined as raw concrete that failed in the confirmation test of fluidity conducted.

  JIS ready-mixed concrete (hereinafter referred to as ready-mixed concrete) (JIS A 5308) manufactured at the current ready-mixed factory is manufactured by mixing cement, aggregate (sand and gravel), water, admixture, etc. Refers to the condition from delivery to unloading. The ready-mixer for construction uses JIS, JASS, etc., and determines the usage time, temperature, etc. in consideration of environmental conditions at the construction site.

  However, surplus components such as raw components that were canceled after manufacturing due to user convenience or natural conditions, surplus components after placement, raw components that failed on site inspection, raw components that could not be delivered by the scheduled time, Generally, disposal processing, solid-liquid separation processing, disposal, etc. are performed.

  The cost associated with this is borne by the raw control company. Such surplus kon varies depending on the factory scale and regional differences, but there is also a report of 3 to 4% of the sales volume (symbiotic cooperative association report).

  In addition, natural sand and gravel are used in the preparation of ready-mixed food, and it is mixed in the ready-mixed food at a mass ratio of about 80%. Therefore, the disposal of surplus kon means the same as the disposal of natural resources.

  Most of the surplus raw concrete is brought back to the raw concrete factory and processed into industrial waste. In addition, aggregates classified in the processing process may be reused. However, most of the ready-mix factories manufacture ready-mixed concrete for use in construction. There are few cases where it is effectively used as raw material for raw materials because of the reason that this image gives a bad impression to customers.

  On the other hand, the manufacture of concrete products (precast concrete) is often produced in product factories, and unlike raw concrete for construction, there is no provision for handling until placement. In addition, there are a wide variety of concrete products, and the degree of freedom to use various mixtures and admixtures is greater than that for construction concrete.

  At present, there are cases where concrete blocks and the like are manufactured by placing them in a formwork as a reuse of surplus raw concrete. However, most of the cured products are not used for quality control in the state of raw concrete (before curing) that affects strength quality, and are used for applications that do not cause problems with the structure. Yes.

As a method of manufacturing reclaimed concrete, there are the following patent documents, such as pile head surplus parts removed after casting cast-in-place concrete piles, and it is difficult to use as recycled aggregate. The entire amount of waste concrete mass containing weak concrete part is effectively used as aggregate of recycled concrete.
JP 2006-326906 A

  This Patent Document 1 is a method for producing recycled concrete using raw concrete made of water, cement and aggregate, crushing a plurality of concrete blocks having different strengths, and using the entire amount of the crushed material as the aggregate. Based on the strength required for recycled concrete, the mixing ratio of concrete lumps having different strengths is adjusted, and the total amount of crushed material of these concrete lumps is used as an aggregate.

  The strength of each concrete block is lower than the strength of the cement paste portion of recycled concrete, and the mixing ratio of concrete blocks having different strengths at a certain water-cement ratio and aggregate addition ratio and the strength of recycled concrete Then, the mixing ratio of the concrete blocks having different strengths is determined based on this relationship.

  The above-mentioned patent document 1 regenerates all the fine and coarse particles obtained by crushing and crushing a concrete lump generated when demolishing an existing concrete structure from the viewpoint of effective use of resources. It is proposed to be used as an aggregate of concrete, and is not intended to reuse surplus surplus waste, nor does it bring about an economic effect of reducing the labor of processing waste waste surplus waste.

  The object of the present invention is to eliminate the inconveniences of the conventional example, and to process and dispose of surplus raw material in the raw material manufacturer, thereby losing energy loss and economic burden associated with these operations, etc., and making effective use of natural resources. A method for reusing surplus concrete that can be produced is provided.

  In order to achieve the above object, the present invention is manufactured in a ready-mixed factory at a ready-mixed factory, transported by a dedicated transporter equipped with a stirring device after manufacture, and unloaded in time, Cement is added to surplus raw con that is a raw con that has failed in the confirmation test for fluidity, etc. conducted on site, and is mixed with other surplus raw cond. The gist is to select one of these and adjust the water-cement ratio (W / C) to be used as a raw material for concrete products.

In addition, the present invention adjusts the water-cement ratio (W / C), measures the unit water amount of surplus raw concrete, and the unit water amount (the amount of water contained per 1 m ^{3 of} raw concrete) contributes to the strength quality of the concrete product. The gist is to confirm by confirming that the water cement ratio (W / C) is within a usable range.

According to the first to third aspects of the present invention, most of the ready-mixed kon used at the construction site is manufactured with a predetermined composition at the ready-mixed factory, and a dedicated agitator (stirring device) is mounted after the manufacture. It is transported with a transport vehicle (raw concrete car), and unloading is carried out within the prescribed time in handling the raw concrete for construction, but the raw concrete that could not be unloaded within this time, surplus raw concrete, on-site Raw kon which failed in the confirmation test such as fluidity carried out is returned to the manufacturing factory and discarded as surplus raw corn as it is, or surplus kon is classified in the factory (solid-liquid separation process), It is processed as industrial waste by volume reduction treatment, etc., aggregates collected after classification are used in our own factory, and used as roadbed materials, but surplus raw concrete is used without such treatment be able to.

  The composition of ready-mixed concrete for construction is different in each construction site, and the surplus ready-mixed concrete is unnecessary concrete in the construction site, and there are cases where the cleaning water of the concrete pump is mixed. In ready-mixed cars, water is added to facilitate subsequent cleaning, so it must be considered different from the concrete composition at the time of shipment.

  In other words, the mix of ready-mixed kon loaded on each live-con vehicle that brings back surplus kon from the site is not stable and must be considered to be all different.

  The present invention measures the water / cement ratio (W / C) of unnecessary surplus concrete that is often disposed of in general, and improves the W / C to meet the required performance of concrete products depending on the application. Therefore, in order to reuse as raw concrete for concrete products, it is a regeneration technology for surplus raw concrete that manufactures raw concrete by adding cement or admixture afterwards. As a result, the quality of the concrete product can be ensured while saving the raw material for the concrete product.

  Aggregate classified in the process of surplus raw concrete may be reused, but many raw concrete factories manufacture raw concrete for construction, and control and reuse according to quality regulations in the production of raw concrete for construction There are few cases where the image of raw kon is used effectively as raw konbu raw material because of the bad impression on customers.

  The present invention is used as a raw material for concrete products (precast concrete), and the manufacture of concrete products (precast concrete) is often produced in product factories. There is no provision for this. In addition, there are a wide variety of concrete products, and the degree of freedom to use various mixtures and admixtures is greater than that for construction concrete.

  At present, there are cases where concrete blocks and the like are manufactured by placing them in a formwork as a reuse of surplus raw concrete. However, most of the cured products are not used for quality control in the state of raw concrete (before curing) that affects strength quality, and are used for applications that do not cause problems with the structure. Yes.

Furthermore, according to the present invention, it is known that the strength of concrete is related to the water cement ratio (W / C), and the inverse cement water ratio (C / W) is proportional to the strength in a linear function. However, based on this highly reliable theory, a range of W / C for quality control is set based on the target strength of concrete products using surplus surplus concrete, and multiple surplus surplus components are used. Can be made a quality that can be used for ready-mixed concrete products.

As described above, the method for reusing ready-mixed concrete according to the present invention eliminates the energy loss and economic burden associated with these operations, etc., in the processing and disposal of surplus ready-mixed concrete in the ready-mixed manufacturer, and aims to effectively use natural resources. Is something that can be done. Specifically, it has the following effects.
1) Economic effects Earlier, it was stated that 3-4% of the sales volume of ready-mixed food is surplus. The profit and loss of the ready-mix factory is about several percent, while 3 to 4% of surplus ready-mixed can be used as valuable resources, which leads to an improvement in profit and loss. In addition, the expansion of cooperation between ready-mixed concrete factories and product factories can produce concrete products, which leads to cost reduction of concrete products.
2) Environmental effects Effective use of natural resources and energy saving associated with concrete product manufacturing.
3) Effective utilization of surplus raw concrete There are cases where surplus raw concrete is separated and classified and used as raw aggregate or roadbed material. Compared with these effective utilization methods, in the case of the present invention, the labor of classifying surplus raw waste, the loss of energy, and the amount of waste generated are reduced in terms that the surplus raw waste can be used as it is. In addition, the amount of compression is further increased by cooperation with multiple factories.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As a first embodiment of the present invention, a ready-mixed container manufactured in a ready-mixed factory at a ready-mixed factory and transported by a dedicated transporter equipped with a stirring device after manufacture and unloaded in time, surplus As a raw material for concrete products by adjusting the cement-to-water ratio (W / C) by post-adding cement to surplus ready-mixed concrete that has failed in the confirmation test for fluidity, etc. It is what you use.

  In the method for recycling ready-mixed concrete according to the present invention, strength is set mainly by adjusting W / C, and its form is shown in the flow charts of FIGS. Although the 1st form in it is set as the post-addition cement, first, the processing flow of the surplus raw-comb in a general raw-con factory is first demonstrated with reference to FIG.

  When processing surplus cooked rice at a ready-mixed plant, it is added to an agitator of a ready-mixed vehicle with surplus cooked food, and then discharged, solid-liquid separated, and separated into coarse particles and suspended water. Coarse particles are reused as recovered aggregate or RC material (roadbed material) or disposed as waste.

  On the other hand, sludge is agglomerated and reduced in volume with a filter press or the like for industrial waste disposal. Moreover, when solid-liquid separation is not performed, the surplus raw concrete is hardened and disposed of as industrial waste as concrete waste (concrete waste).

  On the other hand, the present invention is manufactured in a ready-mixed factory at a ready-mixed plant, transported by a dedicated transporter equipped with a stirring device after manufacture, and unloaded in time, unprocessed ready-mixed, Adjust the water-cement ratio (W / C) of surplus raw concrete that is unacceptable in the fluidity test conducted at the site, add the cement and water afterwards, and use it as a raw material for concrete products . Further, if necessary, the recycle blending is adjusted by selecting and examining reuse in the flowchart shown in FIG.

Furthermore, the water cement ratio (W / C) is adjusted by measuring the unit water volume of surplus raw concrete, and the water quantity (the amount of water contained per 1 m ^{3 of} raw concrete) matches the strength quality of the concrete product. It is confirmed by confirming that the ratio is within the usable range in terms of the ratio (W / C).

In other words, when using surplus raw concrete for concrete products (precast concrete), in order to adjust the water-cement ratio (W / C), the cement or water content is adjusted, re-kneaded, and is subject to disposal. as a management method of producing the available concrete (refresh concrete) playing the surplus production configuration, to measure the unit water surplus raw Con, the unit water amount (amount of water contained in the fresh concrete 1 m ³ per) are of concrete products After confirming that the water cement ratio (W / C) suitable for strength quality is within the usable range, surplus raw concrete is used as a raw material for concrete products.

  When manufacturing a concrete product using surplus surplus concrete, it can be used even if there are multiple types of surplus surplus concrete. The term “plurality” as used herein refers to the number of surplus raw concrete transportation vehicles (raw concrete vehicles).

  The ready-mixed concrete used at the construction site is transported when the quality and composition of the ready-mixed concrete loaded at the factory shipment is clarified. However, surplus kon may be watered on site. Therefore, it is safer to consider that the unit water volume of the loaded raw concrete differs depending on the raw concrete car.

  Further, surplus raw food containers include raw food containers that have been canceled before being loaded onto a raw food container car at the time of shipment, and raw food containers that have not been made into a predetermined composition due to problems during manufacturing.

  There may be a plurality of surplus cookers shown in FIG. 1, and even if the W / C of each cooker is different, it is confirmed that the W / C converted from the unit amount of water when these are mixed is in a range suitable for the quality. If possible, it is determined that the required performance is satisfied. However, if the starting time of the setting of the ready-mixed concrete that is affected by the hydration of the ready-mixed raw material cement is set to 5 to 6 hours, it is not used as a raw material for the concrete product if there is only one type of surplus ready-made concrete that will pass the starting time. Like that.

  In other words, setting W / C within a range that satisfies the required quality increases the possibility of ensuring strength quality. However, since the quality is not promised after the start time of the live control, such live control is not guaranteed. Do not use. However, since the initial start time varies depending on the influence of the delay agent and the temperature, the initial start time for management is managed as a usable time in consideration of these.

  The unit water amount is measured using a method selected from a method of obtaining a sample by drying, a method of obtaining from a unit volume mass, a method of obtaining electrically, a method of using a reagent, and a method of using radiation. However, in the case of using a plurality of surplus kon, it is less likely to be affected by an error that differs depending on the measurement method when unified to one unit water amount measurement method.

  Concrete products are shipped in a state where a predetermined strength and quality can be ensured. The determination may be made by measuring the strength from a separately prepared specimen for strength measurement at the time of manufacture, or a method of directly measuring the product using a test hammer. The strength determination is obtained from the converted value of the test hammer and the relational expression obtained from the actual strength test.

  Although the case where the amount of unit cement is increased by the post-added cement has been described in the first embodiment, the second embodiment is mixing with other surplus kon. W / C is adjusted by changing the mixing ratio with surplus raw concrete having different W / C.

  Furthermore, you may make it adjust W / C by adding kneading water as 3rd Embodiment. That is, it is a case where moisture is added in the setting of W / C.

  In general, surplus cooked rice is returned to the manufacturer's cooker plant and processed. Therefore, the concrete product manufacturing place will be a ready-mixed factory. However, unlike the concrete product manufacturing factory, the ready-mix factory may not be able to secure a curing place or personnel associated with the concrete product manufacturing, so several ready-mixed factories will manufacture in cooperation.

  For that purpose, it is also necessary to share information on surplus raw kon (W / C, time after kneading, presence / absence of water addition, etc.). In addition, a network that allows the surplus cookers to easily adjust the W / C and the like required for the product to be manufactured is constructed so that these can be used at the participating plant factories.

  FIG. 3 shows an image of information sharing using surplus raw food. Vehicles equipped with surplus raw concrete that want to return to the participating raw concrete factories use the communication line to register information with the central management and provide information to product manufacturers who use surplus raw concrete.

  As a result, the raw concrete truck loaded with surplus raw concrete can be supplied to other users without returning to the manufacturer's factory. In addition, since the manufacturer can obtain the surplus kon corresponding to the required quality of the product from several places and prepare for manufacturing adjustment, the timing that can be used within the pot life is not lost.

  By making such information available not only between ready-mixed factories but also in concrete product factories, it can be supplied as raw materials for more advanced products than concrete products that can be manufactured in ready-mixed factories. Become.

  In concrete product factories, there are many opportunities not only to use advanced bar arrangements and formwork depending on the product application, but also to develop these.

  On the other hand, in the ready-mix factory, the use of surplus cooked rice is only used as a destination, and it is easy to use unfinished products and simple formwork, so the variety of uses is inferior.

  In order to use the surplus concrete as a raw material for the concrete product, a slurry may be added to the surplus raw concrete in FIG.

  In general, when a polymer-based admixture is added later, there are many cases in which high-speed stirring is performed with an agitator mounted on a ready-mixed vehicle.

  However, in the addition of the cement, the mixing efficiency deteriorates if the added amount increases even if the cement is added to the agitator mounted on the ready-mixed vehicle directly with the addition of the cement.

  When re-kneading by adding an additive such as cement to the surplus raw kon, what can be added to the addition target to be slurried is added to the slurry and mixed. FIG. 4 and FIG. 5 show images in the case of adding the slurry to the surplus kon. Although FIG. 5 shows a batch mixer, a continuous mixer may be used.

  When using an existing mixer or a special mixer for re-kneading the surplus kon, if it cannot be put directly into the mixer, supply the surplus kon using a pump, and stir and mix with the object to be mixed .

  Next, the method for calculating W / C of surplus corn will be described in more detail. Fig. 6 is a schematic diagram of the state of raw kon and surplus raw kon at the time of manufacture as showing the basis for calculating W / C of surplus raw kon. Basically, sand, gravel and cement in surplus kon are Remains in the state ratio. The amount that fluctuates is often the amount of water.

  That is, in a general concrete blending setting, the addition ratio of cement and sand / gravel is not extremely changed, and the range of the moisture addition ratio is small. For example, when expressed in terms of moisture content, the amount of change is as small as 7 to 10% and about 3%. In the cement, the adhesive force due to the hydration reaction with the relatively small amount of moisture is integrated with the aggregate and greatly affects the strength. The strong correlation between W / C and strength is the relationship between the extremely small amount of water and the amount of cement, so adjustment of a very small amount of moisture change is important. In addition, it can be said that the strength in blending is set on the basis of the extremely small width W / C.

  That is, in the case of general concrete, the strength can be estimated by setting W / C without knowing the exact volume.

If it demonstrates in FIG. 9, the mixing | blending setting suitable for the required intensity | strength of a concrete product can be performed in the following procedures.
・ Cement of surplus concrete and S / G (fine aggregate and coarse aggregate) remain the same.
Therefore, since W / C is a mass ratio, ΔWwt may be obtained.
-W '/ C is easily obtained by measuring the unit water amount W' of surplus raw concrete.

Next, in order to set the W / C required for the product and to change the W / C of the surplus control unit,
(1) Water is added if the surplus raw food W ′ / C is smaller than the product W / C.
(2) When surplus kon W '/ C is larger than product W / C, cement is added.
(3) In the case of using a plurality of surplus crumbs, W ′ / W of each surplus crumb is obtained to obtain the ratio of the total ΣW ′ of each surplus crumb and ΣC which is a cement mass meter.
(4) The increase / decrease in the W / C of a plurality of surplus corn is adjusted by using the result calculated in (3) and (1) or (2) together.
-When placing in a formwork, since it calculates with a volume, in order to obtain | require a required volume, it is necessary to obtain | require synthetic | combination volume (SIGMA) V.
(5) The increased or decreased A ′ is obtained by a test using an air meter or the like. Or it calculates | requires by actually measuring the wet density (rho) 'of the surplus raw synthetic | combination synthesized. Thereby, the volume V ′ is obtained.
(6) When calculating the ratio of each volume,
Sum of each volume excluding air amount Va ′ Vx = {(Wwt / ρw) + (W / C / ρc) + (Wg / ρg) + (Ws / ρs)}
Sum of each mass for each volume Wx = Wwt + W / C + Wg + Ws
Wet density ρx = Wx / Vx obtained by removing air amount ΔVa ′
The air volume VA ′ is a value obtained by subtracting Vx from the volume V ′ obtained from the actually measured wet density in (5).
VA '= V'-Vx

  The example which mixed the raw concrete from which said 2nd Embodiment differs is demonstrated.

  A compression test was performed by setting the mixing ratio from W / C for different surplus raw kon A and B shown in Table 1 below. In this case, the expression strength target is the quality strength of the concrete product. Since the test result exceeds the expression intensity target, the strength quality is satisfied.

The expression strength target value is called nominal strength in the mix of ready-mixed concrete, and shows the same tendency as the relationship with W / C of surplus concrete, so there is no problem with strength and it can be applied. .
Table 1 below shows the relationship between strength and W / C when different surplus kon after 4 hours of pot life is mixed.
The W / C of surplus kon of A and B is calculated from the unit amount of water.
W + C of A + B is calculated from W / C of A and B.

  FIG. 7 shows the relationship between W / C and compression strength of different surplus corn.

Next, an example of the post-added cement of the first embodiment will be further described.
Table 2 below shows the composition at the time of shipment of ready-mixed concrete.

The unit water amount of surplus raw concrete at the time of shipment shown in Table 2 above was measured by a microwave oven method, and a result of 199.9 kg / m ³ was obtained. From the ratio with the amount of cement in the mixture, W / C = 57.1% is obtained. Here, the blending is determined so that the W / C of the ready-mixed concrete used for the product concrete is 55%.

  Since the freshly cooked kon varies depending on the amount of water added, moisture and sand / gravel may be separated and settled.Therefore, the composition of the surplus kon is not estimated from the wet density. It may be calculated from the wet density while taking into account the state of the raw concrete. In that case, it is preferable to consider the amount of air.

In this example, when converted to moisture 24.9 + W / C shown in Table 2, 193.9 / 350 = 55.4%, and the blending amount per unit volume in this state was determined. At that time, since the fine aggregate S (sand) and coarse aggregate G (gravel) are reduced in volume in the same way as the volume of cement is reduced, the average density (specific gravity) of sand and gravel is shown in Table-2. It is necessary to calculate. Since the density (specific gravity) of cement and water is stable, it can be easily obtained by reverse calculation.
1000- (350 / 3.15) + (175/1) = 713.9L Average density = 1.788 / 713.9 = 2.505

In this example, it was estimated that the wet density of surplus kon decreased due to an increase in moisture, and the volume of cement, sand and gravel decreased accordingly. In other words, each blending amount per 1 m ³ (1000 L) of surplus kon is obtained by calculating backward from the moisture content of surplus kon.

Next, the blending amount for making the concrete product W / C = 55% is obtained by blending cement per 1 m ³ of surplus kon. In this calculation, the cement mass is obtained by calculating backward from the water content, and 363.4 kg / m ³ is obtained. Therefore, W / C = 55% can be set by adding 13.4 kg of the cement shortage.

Table 3 below shows the composition of each ready-mixed state.

  Since Table 3 calculates W / C based on the raw concrete volume, it was assumed that the volume of sand and gravel was reduced by the amount of fresh raw concrete at the time of shipment. On the other hand, the ready-mixed concrete recycled for concrete products calculates the amount of cement from the set W / C and the amount of water, so that the volume of sand and gravel is further reduced in the formulation.

In actual work, since W / C is merely reduced, the cement shortage obtained from Table 3 is simply added and agitated according to the amount of surplus kon.
In the increase / decrease of W / C in the mixing of concrete, when the amount of cement is constant, the mixing is suppressed so that the separation due to the amount of moisture in the ready-mixed corn is less than the volume of the ready-made kon, so the increase / decrease in the amount of moisture is negligible. The amount of cement is large, and the influence of cement adhesive strength on the change in W / C is great.

  As shown in FIG. 8, the smaller the W / C, the greater the strength. At the W / C = 55% of the post-added cement, it is intermediate between the compressive strength results at the time of shipment and the surplus surplus concrete. It can be seen that even after cement addition based on W / C, it can be adequately handled.

  In the case of post-added cement, when re-stirring is performed smoothly by adding cement, it is preferable to add admixtures such as a fluidizing agent and a water reducing agent according to the fourth embodiment. The addition amount of the admixture may be handled in the same manner as general concrete blending.

  When high-strength ready-mixed concrete becomes surplus concrete, add after sand. The W / C of high-strength raw concrete is small compared to other raw concrete, so when using this, it is necessary to adjust by adding moisture.

At that time, increasing the amount of water may affect the bleeding (material separation) and the like, so there are cases where the aggregate needs to be added later. In this embodiment, the aggregate amount was adjusted simultaneously with the addition of water.
(1) Shipped as a blend of high-strength concrete (60-55-20N, air volume 3%).
And compression strength at the age of 28 days, was 72.2N / mm ^2.

(2) About the ready-mixed concrete shipped with the mixing | blending of said Table 4, it returned to the factory as a surplus ready-mixed state in 150kg / m < ³ > hydrated state. (For the amount of water, the test described in the previous section was performed.)
-Since it was found that 150 kg / m ^{3 was} added, the apparent W / C was (170 + 150/532) × 100 = 60%.
・ Volume increased by 0.15 m ³ , and apparent formulation was as follows.
-Material separation occurred in this state. In this state, it is usually a solid-liquid separation process. However, since the material is separated (bleeding) with a large amount of water, it can be reused by adding sand as an admixture without changing W / C. did. In this case, sand was used because it was desired to increase the viscosity and reduce the influence on fluidity by using an admixture such as slag with small particle size. On the contrary, an admixture with a small particle diameter is preferable when it is desired to have viscosity.

(3) A formulation for improving handling (usability) was examined without increasing the viscosity, and sand was added after 300 kg / m ³ .
As a result, the volume increased by 0.114 m ³ (300 kg ÷ ρ2.63 = 0.114), and the apparent composition was as follows.
・ Material separation was eliminated, workability was improved, and handling sufficient for placing was obtained. The slump flow was 51cm and the air volume was 2.4%.
And compression strength at the age of 28 days, was 23.9N / mm ^2.
Thus, in the present invention, other admixtures may be added later instead of sand. However, it must be formulated in consideration of the density of the admixture.

  Since concrete products have different shapes and dimensions, the strength of the concrete itself is generally collected by collecting specimens for compression testing at the time of production of raw concrete, and testing at a specified age. The same method is used for the quality check of the compression strength of the present invention. However, the quality of concrete products must be satisfied at the time of shipment.

  In concrete products, since there is a correlation between the strength of concrete and the hardness of the concrete surface, there is a test hammer (or Schmidt hammer) as a measuring instrument to measure the rebound hardness. Therefore, it can be measured without damaging the product. However, the accuracy is not always stable.

  Therefore, the correlation between the product made from surplus concrete and the value of the compression test was determined and used. FIG. 9 shows the results.

  Moreover, each compressive strength was expressed more than 20% compared with the nominal strength used by the mixing | blending of concrete. As a result, it was determined that the blending correction based on the W / C using surplus raw concrete can be used sufficiently without departing from the strength characteristics of a general concrete blending.

  In addition, in the method of manufacturing concrete using surplus raw concrete, the use can be made possible even when the water cement ratio (W / C) converted from the unit water amount satisfying the requirement of the concrete product is deviated.

  This can increase the amount of surplus corn that can be used for concrete products. However, the concept of pot life and the quality control of products as described in the previous draft shall be the same.

  About surplus kon, unit water quantity is measured based on W / C at the time of shipment, current unit water quantity is obtained, and W / C is converted. Up to this point, the same as in the previous section. Here, even in a state where the required performance is not satisfied, as a possibility of reuse shown in the flowchart of FIG. 2, the post-addition fluidizing agent or the like described above is added. A water reducing agent or the like is used when fluidity at the time of placing is ensured by the structure of the formwork or bar arrangement, the amount of placement, or the like, or when remixing is difficult by blending.

  As a fifth embodiment, fiber addition is performed. This is a case where mixing of fibers (polypropylene fiber, vinylon fiber, steel fiber, etc.) is required for concrete products.

  In the sixth embodiment, an admixture is added. FIG. 10 shows a regenerated blend in which an admixture is added afterwards. The part A in the figure is a surplus raw mix component, and the admixture of the B part is mixed and regenerated into a ready mix for concrete products. As an admixture, slag, calcium carbonate, fly ash, papermaking sludge, ready-mixed sludge and aggregate (aggregates include recycled aggregates such as recycled sand) etc. are mixed to adjust the density and workability etc. Also improve the effective formulation.

  Mixing of fibers and admixtures cannot be solved by W / C alone, so a compounding test may be required in advance. If the compound has already been proven, add fibers and admixtures. In some cases, it is possible to adjust the W / C from the excluded formulation.

  As shown in FIG. 10, it is possible to modify the blending by considering the portion A as a concrete foundation blend and considering the W / C as a reference. Moreover, in such a case, not only W / C but also the fluidity in the raw cooking state may be used as the management value.

It is a flowchart which shows 1st Embodiment of the reuse method of the ready-mixed concrete of this invention. It is a flowchart which shows other embodiment of the reuse method of the ready-mixed concrete of this invention. It is a sharing image figure of surplus raw kon information. It is explanatory drawing of the 1st example in the case of adding a slurry to surplus raw concrete. It is explanatory drawing of the 2nd example in the case of adding a slurry to surplus raw concrete. It is explanatory drawing which shows the calculation basis of W / C of surplus raw control. It is a graph which shows W / C and compression strength of different surplus raw material. It is a graph which shows the compressive strength result which added post-added cement to surplus raw concrete. It is a correlation figure of the compressive strength of concrete using a surplus raw concrete, and a test hammer. It is a conceptual diagram of the reproduction | regeneration mixing | blending using a mixture. It is a flowchart which shows the processing concept of surplus raw material.

Claims (4)

  It is manufactured at a ready-mixed factory with a specified composition, and after production, it is transported to a construction site by a dedicated transport vehicle equipped with a stirring device. It is characterized by adjusting the water-cement ratio (W / C) by post-adding cement to surplus raw concrete that has failed in the confirmation test of fluidity, etc., and using it as a raw material for concrete products How to reuse surplus concrete.   It is manufactured at a ready-mixed factory with a specified composition, and after production, it is transported to a construction site by a dedicated transport vehicle equipped with a stirring device. Adjust the water-cement ratio (W / C) by mixing surplus kon, which is a raw kon that has failed the confirmation test for fluidity, etc. with other surplus kon, and use it as a raw material for concrete products. A method of reusing surplus ready-mixed concrete.   It is manufactured at a ready-mixed factory with a specified composition, and after production, it is transported to a construction site by a dedicated transport vehicle equipped with a stirring device. It is characterized by adjusting the water-cement ratio (W / C) by adding additional kneaded water to surplus raw concrete that has failed the confirmation test for fluidity, etc., and using it as a raw material for concrete products Recycled surplus concrete. To adjust the water cement ratio (W / C), measure the unit water volume of surplus raw concrete, and the unit water quantity (the amount of water contained per 1 m ^{3 of} raw concrete) is the water cement ratio (W The method for reusing surplus concrete according to any one of claims 1 to 3, which is carried out after confirming that it is within a usable range in terms of / C).