JP5597467B2 - Manufacturing method of recycled concrete - Google Patents

Description

The present invention relates to a method for producing recycled concrete using a total amount of recycled materials such as recycled coarse aggregate and recycled fine aggregate obtained by treating waste concrete from demolition concrete.

  Conventionally, most of the waste concrete materials generated by the dismantling of aging concrete structures are used as recycled roadbed materials and backfill materials. The reason why there are many uses by these methods is that it is possible to use all the waste concrete with a small amount of processing, and that the demand for new road construction is expected to be large. However, since there is a high possibility that the supply and demand balance as recycled roadbed materials and backfill materials will be lost in the future, it is necessary to search for methods other than these reuse methods. Then, utilization as a recycled aggregate which collects an aggregate from waste concrete and uses it again as an aggregate for concrete has been examined. However, the use results are very few. The reason why the use of recycled aggregates does not progress is that, when producing high-quality recycled aggregates, a large amount of fine powder (by-product fine powder) is produced as a by-product at the time of production, but its usage has not yet been established. One of the major causes.

  In recent years, it is expected that a large amount of concrete waste material will be generated at the time of renewal of a large amount of concrete structures constructed during the period of high economic growth in the 1970s. Especially when a large amount of concrete is discharged from nuclear power plants and related facilities with strict environmental regulations in a short period of time, all of the effective use of resources, mass processing (especially by-product fine powder processing), and environmental load reduction are all performed. From the viewpoint of satisfying, it is necessary to consider the reuse of waste concrete. As one of them, a technology has been developed that treats the waste concrete from the demolished concrete to make the entire amount into recycled material and recycles it all.

  For example, Patent Literature 1 discloses that recycled coarse aggregate is selected from raw concrete concrete waste including fine aggregate made of cement clinker powder, and the residue is fired to obtain a cement clinker. This material is sorted into powder and other powders, and gypsum is added to this powder to make recycled cement. This recycled cement, recycled coarse aggregate, recycled fine aggregate, and water are kneaded to achieve the same performance as the original concrete. A method for obtaining a volume of recycled concrete is disclosed.

  Further, Patent Document 2 discloses ready-mixed concrete in which all waste concrete blocks made of pulverized waste concrete blocks, cement, and water are reused.

  Patent Document 3 discloses an interlocking block in which the entire amount of demolished concrete is reused as recycled aggregate.

  In Non-patent Document 1, recycled coarse aggregate, recycled fine aggregate, and recycled fine powder are taken out by a wet sorting method. The recycled coarse aggregate and recycled fine aggregate are used as concrete aggregate, and the recycled fine powder is cement. It is disclosed that by making it a part of the raw material, it is possible to achieve zero emission of the concrete waste material.

  On the other hand, in the conventional recycled concrete technology using recycled aggregate and by-product fine powder obtained by crushing waste concrete, when trying to use the total amount of the obtained recycled aggregate and by-product fine powder, in general, new cement or natural Because of the large amount of aggregate used, the volume of the new recycled concrete obtained will be several to several tens of times that of the original waste concrete. Therefore, it is necessary to prevent the volume of the new recycled concrete obtained from increasing significantly. The technique described in Patent Document 1 takes this point into consideration as described above.

Japanese Patent Laid-Open No. 10-130045 JP 2001-130944 A JP 2007-31241 A

"Recycling of all concrete waste by wet sorting", Annual report of concrete engineering, Vol.27, No.1,2005

  As mentioned above, there are some technologies that recycle all processed concrete waste and achieve zero emissions of concrete waste. However, the technique of Patent Document 1 is effective only for recyclable raw concrete scraps whose fine aggregates are crushed cement clinker, and cannot be applied to general concrete scraps.

  In the technology of Patent Document 2, since fresh concrete is obtained by adding a large amount of cement or the like, the volume of this ready concrete increases significantly compared to the volume of the original waste concrete. It is not preferable because of the decrease in demand. Moreover, since quality adjustment of the pulverized material obtained by pulverizing the waste concrete block is not sufficiently performed, it is difficult to obtain high-quality ready-mixed concrete with stable quality.

  Even in the technique of Patent Document 3, since an interlocking block is obtained by newly adding a large amount of cement or the like, the volume tends to increase compared to the original demolished concrete, which is not preferable. Moreover, since the demolished concrete is only divided into two parts: a disassembled coarse aggregate exceeding a predetermined size and a fine granule having a predetermined size or less, the fine particles contain a large amount of fine powder. Accordingly, they can be used as an interlocking block manufactured by immediate removal, but cannot be used as a concrete material having performance close to that of ordinary concrete.

With the technology of Non-Patent Document 1, zero emissions can be achieved by recycling the entire amount of concrete waste, but the amount of fine powder generated is significantly increased because recycled aggregate is obtained through advanced processing. The fine powder is used as a part of the cement raw material for producing the cement clinker, but there is a limit to the amount that can be added to the cement raw material, and it is necessary to produce a large amount of cement. Recently, the demand for cement has been remarkably reduced, so it is difficult to recycle all the fine powder generated using only cement raw materials. Even if recycled concrete with good performance is obtained, the volume of recycled concrete is increased compared with the volume of the original concrete waste, and a large amount of recycled concrete is produced.
The present invention has been made in light of the background and problems as described above, and its purpose is as follows:

(1) Using all the recycled materials (recycled coarse aggregate, recycled fine aggregate, by-product fine powder) obtained by processing waste concrete, the volume of the recycled concrete produced is significantly larger than the waste concrete that is the starting material. Providing recycled concrete that exhibits practical performance in the field of civil engineering and architecture (2) Providing a method for manufacturing the recycled concrete

(3) Providing a method for treating waste concrete that produces less by-product fines and is useful for the production of recycled concrete

(4) To provide a treatment method capable of dealing with most of general waste concrete discharged by dismantling of general concrete structures.

As a result of intensive studies to achieve the above object, the present inventors have limited the quality and processing conditions when producing recycled aggregate from waste concrete using a G grinder and an S grinder, What is necessary is just to make the quantity of byproduct fine powder generate | occur | produced when processing with the said S grinder to obtain a reproduction | regeneration fine aggregate to 10 to 25 weight% of the said waste concrete, The said byproduct fine powder is a part of fine bone The present inventors have completed the invention by finding out that it is sufficient to replace the material and use the rest as a part of the cement raw material. That is,

The invention of the reclaimed concrete according to claim 1 of the present application is “ a medium-quality reclaimed coarse aggregate of reclaimed coarse aggregate M defined in Appendix A of JIS standard A5022, obtained by treating waste concrete from demolition concrete, the quality of the reproduced fine aggregate in the reproducing fine aggregate M as defined in Annex a of JIS standard A5022, using a total amount of recycled material consisting of by-product fines generated when obtaining the reproduction fine aggregate, one or, and the volume of the playback concrete to be manufactured method of manufacturing as the reproduction concrete becomes more than 3.5 times the volume of the waste concrete as a starting material, in the reproduction concrete, the by-product fine powder the waste concrete The main coarse aggregate is the regenerated coarse aggregate (A), and the main fine aggregate is a fine aggregate containing the regenerated fine aggregate and the by-product fine powder within 20% by weight. It is an aggregate (B), and the cement is a cement (C) manufactured by using a cement clinker obtained by firing a cement raw material containing 10% by weight or less of the by-product fine powder other than for mixing the fine aggregate. There is a manufacturing method of recycled concrete characterized in that concrete is manufactured using the recycled materials (A) to (C) as main materials .

  Demolition concrete is a concrete block that contains foreign objects such as rebars that are generated when dismantling general concrete structures such as buildings and factories. Waste concrete is dismantled to remove large foreign objects such as large reinforcing bars. It is an ordinary concrete lump. Further, the recycled material is a material for reuse in recycled concrete, and specifically, recycled coarse aggregate, recycled fine aggregate, and by-product fine powder. The by-product fine powder is fine particles other than the regenerated fine aggregate generated when producing the regenerated fine aggregate (obtained by processing with the S grinder from the fine particles obtained by processing with the G grinder. Fine particles excluding recycled fine aggregate).

  In the present invention, new recycled concrete is obtained using the entire amount of recycled material produced from waste concrete. The “total amount” referred to in the present invention is a substantially total amount.

  Moreover, in the recycled concrete of the present invention, in addition to using the entire amount of the recycled material, a chemical admixture such as a water reducing agent conventionally used to improve the performance of concrete and a concrete admixture such as fly ash are added, In order to adjust the particle size distribution of the fine aggregate, a little crushed sand or natural sand may be added, or a general ordinary coarse aggregate or a general ordinary fine aggregate may be added to use up all of the recycled material.

  The amount of by-product fine powder used in the recycled concrete of the present invention is 10 to 25% by weight of the waste concrete. If the amount of by-product fine powder obtained from waste concrete exceeds 25% by weight and is intended to be used only with recycled concrete, the volume of recycled concrete becomes significantly larger than the volume of waste concrete. If the content is less than 10% by weight, the quality of the recycled fine aggregate obtained is deteriorated, and a concrete having a desired quality cannot be obtained.

The recycled concrete of the present invention is mainly composed of recycled material obtained by treating waste concrete as described above, but the volume is 3.5 times or less of the volume of waste concrete used as a starting material. It is. For example, when a waste concrete lump having a volume of 100 m ³ is processed to make the whole amount as a recycled material, kneaded water is added to the concrete material using the whole amount of the recycled material and kneaded to newly produce recycled concrete, which is newly obtained. the volume of recycled aggregate concrete is that become 350 meters ³ below. 3.5 times or less is newly used in the manufacturing method of the present invention, which aims to obtain recycled concrete that exhibits practical performance in the field of civil engineering and construction using the total amount of recycled material. As a result of various studies to reduce the production amount of recycled concrete to be produced, the limit was 3.5 times. If it exceeds 3.5 times, the above-mentioned purpose becomes difficult to achieve. The lower limit of the volume is not particularly limited as long as the object can be achieved, but the total amount of water in the concrete and most of the cement are made of materials not derived from waste concrete, and the volume is about 25% in total. Therefore, even when the remaining 75% is all recycled material, it becomes 1.3 times.

  Further, as described above, the recycled concrete of the present invention has practical freshness, strength properties, and durability in the field of civil engineering and architecture. Fresh properties are slump, air volume, bleeding characteristics, and condensation properties. Strength properties are compressive strength and static elastic properties. Durability is freeze-thaw resistance, length change, and neutralization properties. It is.

  It is one of the features of the present invention that all the recycled material obtained from general waste concrete is used to reduce the volume of newly obtained concrete and to have practical performance in the field of civil engineering and construction. This is not in the prior art. The use of the recycled concrete of the present invention includes not only concrete blocks that do not require particularly high strength and excellent durability, such as earthen concrete, discarded concrete, revetment blocks and pavement blocks, but also general civil engineering structures and building structures. Concrete of things.

The recycled concrete produced by the method for producing recycled concrete according to the present invention is a medium-quality recycled coarse aggregate M (A) whose main coarse aggregate is defined in Appendix A of JIS standard A5022, and the main fine aggregate is A fine aggregate (B) comprising medium-quality recycled fine aggregate M as defined in Appendix A of JIS A5022, and by-product fine powder generated when the recycled fine aggregate is manufactured, and cement is the secondary aggregate cement produced by using the cement clinker obtained by calcination of cement raw materials including fresh fines 10 wt% or less (C) Oh Ru.

  Recycled concrete consists of cement, coarse aggregate, fine aggregate, etc., but using the entire amount of recycled material while suppressing the amount of by-product fines, it is the same level as ordinary concrete that demonstrates practical performance in the field of civil engineering and architecture. For this purpose, the recycled aggregate is preferably of medium quality, specifically, recycled coarse aggregate and recycled fine aggregate as defined in Appendix A of JIS standard A5022. If high quality recycled coarse aggregate H and recycled fine aggregate H defined in JIS standard A5021 are manufactured, the amount of by-product fine powder is excessively increased. The low-quality recycled coarse aggregate L and recycled fine aggregate L defined in Annex A of JIS standard A5023 require a small amount of by-product fine powder, but the performance of recycled concrete is practical due to the low quality level. It may happen that it does not.

  Moreover, it is preferable to use a part of the by-product fine powder generated when producing the recycled fine aggregate as a fine aggregate and the rest as a cement raw material. Therefore, in the recycled concrete of the present invention, the main fine aggregate is a fine aggregate (B) composed of recycled fine aggregate and by-product fine powder, and the cement is obtained by firing a cement raw material containing 10% by weight or less of the by-product fine powder. The cement (C) produced using the resulting cement clinker is preferred. As described above, the amount of by-product fine powder obtained from waste concrete is set to a specific range, and by using the by-product fine powder in both the fine aggregate and the cement raw material, the entire amount of recycled material can be used. At the same time, the desired recycled concrete is obtained. Cement (C) is produced using a cement clinker obtained by firing a cement raw material containing 10% by weight or less of by-product fine powder, and the by-product fine powder is mainly used as a substitute for the clay of the cement raw material. The reason why the amount of by-product fine powder added to the cement raw material is 10% by weight or less is that if it exceeds 10% by weight, the quality of the clinker firing and cement clinker is easily affected.

The reproduction concrete produced by the production method of reproducing the concrete of the present invention, in the above fine aggregate (B), the by-product fines Ru der 20 wt% or less at the inner split.

  In the present invention, in order to use the above-mentioned by-product fine powder, which has conventionally been difficult to process, as a recycled concrete material, a part of the fine powder is used as a part of the fine aggregate. It is preferably 20% by weight or less. If it exceeds 20% by weight, it becomes difficult to obtain a recycled concrete having practical fresh properties, strength properties and durability that can be used in the civil engineering and construction fields.

The by-product fine powder is fine powder particles other than the regenerated fine aggregate generated when the regenerated fine aggregate is produced. Since the classification of fine particles is generally performed with a diameter of about 0.15 mm, most of the by-product fine particles obtained have a particle size of 0.15 mm or less. Is 30 to 60%, the absolute dry density is 2.00 to 2.30 g / cm ³ , and the fineness is a brane value of 1000 to 8000 cm ² / g. In some cases, impurities such as Cl and organic matter may be contained, and when there are many impurities, care must be taken when reusing.

Above manufacturing method of reproducing the concrete of the present invention, granulated mass above Sharing, ABS concrete by granulator to 40mm or less, the resulting crushed product was triturated with classification in regeneration coarse aggregate manufacturing attritor A coarse aggregate (A) of medium quality recycled coarse aggregate M is obtained, and the remainder is ground and classified by a grinding machine for production of recycled fine aggregate to obtain medium quality recycled fine aggregate M and by-product fine powder. Part of the by-product fine powder is added to the recycled fine aggregate M as a fine aggregate to obtain a fine aggregate (B), and the remaining by-product fine powder is added to the cement raw material at 10% by weight or less of the total to give a cement (C) from the cement clinker obtained by firing the raw material for cement, it produces concrete recycled materials of (a) ~ (C) as main material.

One of the features of the method for producing recycled concrete of the present invention is that specific recycled materials (recycled coarse aggregate M 1 , recycled fine aggregate M 2 , by-product fine powder) obtained by treating waste concrete with a specific treatment method. The total amount is used as a main material, and a specific processing method is adopted and a specific recycled material obtained by this processing method is used. By these, the recycled concrete which satisfy | fills the objective of the said invention is obtained easily.

In the above specific processing method, first, when the waste concrete contains a reinforcing bar or a steel material, first, a crusher is used to separate the reinforcing bar and the steel material while crushing the concrete. After separating the reinforcing bars and steel materials, a crush of waste concrete is roughly crushed to 40 mm or less using a jaw crusher or impact crusher. Next, the obtained coarsely crushed material is ground with a G grinder and classified to obtain a recycled coarse aggregate M.

  G grinders include a grinder by a screw-type grind method, a grinder by an eccentric rotor-type grind method, a grinder by a mechanical grinding method, and specifically, TRAS (screw-type grind method described later). ), Cyclite (eccentric rotor type grinding method), and other dry recycled coarse aggregate manufacturing machines with grinding action can be applied.

  In the screw-type grinding method, when the main shaft motor and the pedestal pressurizing motor in the grinding device having a screw rotate in opposite directions, the aggregates or the aggregate and the rotating screw come into contact with each other in a compacted state. It removes mortar adhering around the aggregate. The quality can be improved by increasing the number of processing times.

  The eccentric rotor type grinding method mechanically vibrates the processed material put into a grinding device having a rotor that rotates eccentrically, and the particles rub against each other to remove the mortar adhering around the raw aggregate. is there. The quality can be improved by increasing the number of processing times.

  The mechanical grinding method is capable of dry and wet processing, and is a kind of ball mill. The drum body is finely divided by a partition plate, and the processed product is put into a mechanical grinding device filled with iron balls. By rotating the partition plate, the mortar adhering around the raw aggregate is removed.

  In addition, the dry milling machine for producing recycled coarse aggregate is because the recycled material gets wet in wet wet recycled aggregate or recycled fine aggregate manufacturing equipment, making it extremely difficult to handle fine particles. This is because it is not suitable for the present invention.

  Classification after the grinding treatment is performed at 5 mm which is the maximum particle size of the fine aggregate, or 6 to 8 mm which is a little larger. As a classifier, a vibration sieve, an air separator, or the like is used. The reason for classifying at 5 mm is that the maximum particle size of the regenerated fine aggregate obtained in the subsequent process is 5 mm, which matches the general particle size of the fine aggregate, and is easy to handle. The reason why the classification is performed with a slightly larger 6 to 8 mm is to prevent clogging of the sieve during classification.

  When the above-mentioned recycled coarse aggregate alone cannot obtain a coarse aggregate (A) having a suitable particle size distribution as a coarse aggregate for concrete, the amount of recycled fine aggregate and by-product fine powder produced is larger than the amount used as an index. When the amount of recycled coarse aggregate becomes less than the amount to be used as an index, an adjustment stone having an appropriate particle size range may be added. Examples of the adjusting stone include natural coarse aggregates such as river gravel, land gravel, mountain gravel and sea gravel, slag aggregate for concrete (JIS standard A5011), and crushed stone for concrete (JIS standard A5005).

The remaining classified material other than the recycled coarse aggregate M obtained by classification is ground and classified by an S grinder to obtain recycled fine aggregate M and by-product fine powder. As the S grinder, a dry grinder having a grinding action is used. Specifically, a KM polisher and a ball mill described later can be used. Thus, the said reproduction | regeneration fine aggregate M is easily obtained by using combining G grinders, such as TRAS, and S grinders, such as KM polisher. Classification is performed using a vibration sieve, an air separator, or the like. The classification diameter is 0.15 mm, for example.

A part of the by-product fine powder obtained is added to the recycled fine aggregate M as a fine aggregate by 20% by weight or less to obtain a fine aggregate (B). If it exceeds 20% by weight, there will be too many fine powder parts, and it will be difficult to obtain recycled concrete having fresh properties, strength properties and durability that are practical in the field of civil engineering and construction. In addition, when the fine aggregate (B) of suitable particle size distribution cannot be obtained only with the said reproduction | regeneration fine aggregate M and the said byproduct fine powder, or the production amount of the reproduction | regeneration coarse aggregate M is larger than the quantity used as a parameter | index. When the regenerated fine aggregate M becomes less than the amount used as an indicator, adjusted sand having an appropriate particle size range may be added. Examples of the adjustment sand include natural fine sand such as river sand, land sand, mountain sand, sea sand, slag aggregate for concrete (JIS standard A5011), and crushed sand for concrete (JIS standard A5005).

  Using the remaining by-product fine powder used as a part of the fine aggregate as described above, cement (C) is obtained from the cement clinker obtained by adding to the cement raw material and firing the cement raw material. The amount of by-product fine powder added to the cement raw material is preferably 10% by weight or less. If it exceeds 10% by weight, the quality of the clinker firing and cement clinker tends to be affected, which is not preferable. The addition to the cement raw material is performed, for example, by mixing and pulverizing with a raw material mill together with limestone, silica, iron raw material, etc. in a raw material process in cement production.

  In the above, a part of the by-product fine powder is used for the fine aggregate and the rest is used for the cement raw material. However, this does not regulate the order of reuse, and a part of the by-product fine powder is used for the cement raw material. The remainder used may be used for the fine aggregate, and the present invention includes both cases.

  Recycled concrete is manufactured using the specific recycled materials (A) to (C) obtained by the specific processing method as described above as a main material. If necessary, chemical admixtures such as high-performance water reducing agents and cement admixtures such as fly ash, blast furnace slag powder, and silica fume may be used as an auxiliary material. Further, natural aggregate or the like may be added in order to adjust the particle size distribution / mixing of the aggregate. These must be added so that the volume of the obtained recycled concrete is 3.5 times or less the volume of the waste concrete as a starting material. What is necessary is just to perform a manufacturing apparatus and another manufacturing method according to the manufacturing method of the conventional concrete.

The present invention provides a method for preparing a reproduction concrete of the present invention, the reproduction so that the amount of by-product fines generated during the production of the upper Symbol reproducing fine aggregate M is 10 to 25% by weight of waste concrete as a starting material It intends line the ground in the fine aggregate production for the grinder.

One of the features of the production method of the present invention is to control and suppress the amount of by-product fine powder that has been difficult to process. Using a combination of a G grinder and an S grinder, for example, if the coarse aggregate used in recycled concrete is changed to recycled coarse aggregate M , and the main component of fine aggregate is recycled fine aggregate M , these recycled fine bones The amount of by-product fine powder generated when producing the material M can be adjusted to 10 to 25% by weight of the waste concrete used as a starting material. Generation amount of by-product fines less the better, but hardly good quality reproduction fine aggregate M is obtained in less than 10% by weight. If the amount exceeds 25% by weight, the amount of by-product fines generated becomes too large, and when the entire amount is used only for recycled concrete, the amount of recycled concrete produced is much larger than waste concrete, which is preferable from an economic and environmental standpoint. Disappear. If it is in the range of 10 to 25% by weight, the quality of the regenerated aggregate and the amount of by-product fines generated can be kept in a well-balanced manner for the purpose of the present invention.

The invention of the method for producing recycled concrete according to claim 2 of the present application is as follows: “The recycled concrete has a recovery ratio of 25 to 40% with the recycled coarse aggregate M having a recovery ratio of 40 to 60% with respect to the waste concrete. Recycled fine aggregate M is used, and each ratio of the recycled coarse aggregate M, recycled fine aggregate M, and by-product fine powder in the recycled concrete is the recycled coarse aggregate M and recycled fine aggregate M. 2. The method for producing recycled concrete according to claim 1, wherein the mixture is designed so as to be equivalent to each recovery ratio of the by-product fine powder .

One of the characteristics of the production method of the present invention is that the recovery ratios of the recycled coarse aggregate M , the recycled fine aggregate M, and the by-product fine powder are equivalent to the respective blending ratios of the recycled concrete. It is to manufacture by adjusting each processing condition of grinding with the G grinding machine and grinding with the S grinding machine. Based on pre-designed concrete mix of recycled concrete (unit coarse aggregate amount, unit fine aggregate amount, unit cement amount), the blend ratio of recycled coarse aggregate M , recycled fine aggregate M and by-product fines in recycled concrete Obtained and processed by G grinder and S grinder so that the recovered ratio of recycled coarse aggregate M and recycled fine aggregate M substantially matches this ratio. In order to make it coincide, the number of treatments in each grinder, the time during which the grinding action acts in one treatment, the stress of the grinding action, and the like are adjusted. In general, if the amount of by-product fine powder is 10 to 25% by weight, it is easy to adjust. In this way, recycled concrete using the entire amount of recycled materials (recycled coarse aggregate M , recycled fine aggregate M , by-product fine powder) obtained by treating waste concrete by matching each recovery ratio and blending ratio as much as possible. Is easily obtained. In addition, since the obtained recycled coarse aggregate and recycled fine aggregate are of a practical quality, the recycled concrete has fresh properties, strength properties, and durability that are practical in the fields of civil engineering and architecture. In addition, recycled concrete whose volume is not significantly larger (3.5 times or less) than the waste concrete used as a starting material can be easily obtained. Since the volume of by-product fines in recycled concrete greatly affects the volume of recycled concrete as a whole, from the viewpoint of using the entire amount of recycled material and reducing the volume of recycled concrete, Relationships are important.

Processing waste concrete in the preparation process of the reproduction concrete of the invention is to milled classifying waste concrete in the coarse crusher crushed to a crushed product regeneration coarse aggregate producing attritor obtained from demolition concrete recycled crude The amount of by-product fine powder generated when the aggregate M is obtained and the remainder is ground with a grinding machine for producing a recycled fine aggregate to obtain the recycled fine aggregate M is 10 to 25% by weight of the waste concrete. In addition, the recycled coarse bone so that the recovery ratio of the recycled coarse aggregate M is 40 to 60% and the recovered ratio of the recycled fine aggregate M is 25 to 40% by weight with respect to the waste concrete. It is preferable to perform the treatment by adjusting each processing condition of grinding with a mill for producing a material and grinding with a grinder for producing a fine aggregate.

By producing recycled concrete using all the recycled materials obtained by using this processing method, recycled concrete meeting the object of the present invention can be easily obtained. Here, the recovery ratio of the recycled coarse aggregate M is 40 to 60%, and the recovery ratio of the recycled fine aggregate M is 25 to 40%. Since the mixing ratio of the recycled coarse aggregate M in the recycled concrete and the recycled fine aggregate M as a whole is approximately the same, the recovery ratio of the recycled coarse aggregate M and the recycled fine aggregate M should be within the above ranges. Also, the amount of by-product fine powder is likely to be 10 to 25% by weight, and the entire amount of recycled material can be used for recycled concrete. Further, the obtained recycled concrete has a volume that is not significantly larger than 3.5 times the volume of waste concrete as a starting material, and the performance is practical in the field of civil engineering and construction.

As described above, the objects of the present invention are as follows: 1) use of all recycled materials, 2) reduction of the amount of by-product fines, 3) reduction of volume of recycled concrete, 4) civil engineering and construction of recycled concrete. In order to achieve these objectives at the same time , the quality of recycled aggregate and the treatment method of waste concrete are important, and the amount of by-product fines generated is 10 to 25 weight by the above treatment method. %, reproduction recovery ratio 40 to 60% in recycled materials coarse aggregate M, reproduction recovery ratio of fine aggregate M are formed so that 25% to 40% during reproduction material, mid predetermined ratio of recycled aggregate quality This can be easily achieved if waste concrete is treated as described above. Moreover, the mixing ratio of recycled concrete and the recovery ratio of recycled material are easily matched.

With the manufacturing method of the re-mixed concrete of the present invention, can be controlled to the target range suppresses the generation of by-product fines. In addition, the entire amount of processed material (recycled coarse aggregate M , recycled fine aggregate M , by-product fine powder) obtained from the treatment of waste concrete can be reused as recycled material for recycled concrete, and waste that becomes a starting material There is no waste because recycled concrete of 3.5 times the volume of concrete is obtained. In addition, the method for treating waste concrete in the method for producing recycled concrete according to the present invention is a general-purpose method that can cope with a large amount of general waste concrete discharged by dismantling a general concrete structure.

The recycled concrete obtained by the method for producing recycled concrete according to the present invention is mostly made of medium-quality recycled material from waste concrete, but has practical performance in the field of civil engineering and architecture. It is a concrete that can demonstrate practical performance in the field.

It is a flowchart which shows the process process of the processing method of the waste concrete of this invention. It is a flowchart which shows the manufacturing process of the recycled concrete of this invention. It is a figure which shows the kneading | mixing conditions of the recycled concrete of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments described below.

<Waste concrete treatment method>
FIG. 1 is a flowchart showing the processing steps of the waste concrete processing method of the present invention.
The method for treating waste concrete according to the present invention will be described with reference to this figure.

  First, foreign matter such as reinforcing bars and steel materials discharged from a concrete structure discharged by demolition work of the concrete structure or the like is removed using a heavy machine such as a crusher to obtain a waste concrete mass of about several tens of centimeters. Next, this waste concrete lump is crushed to 40 mm or less by a jaw crusher or the like to obtain a crushed material.

  The obtained crushed material of 40 mm or less is ground by a G grinder, and the cement mortar and cement paste that are mainly attached to the coarse aggregate are peeled off. Then, the treated product is passed through a vibration sieve and classified at 8 mm, and is divided into fine granules composed of recycled coarse aggregate of 8 mm or more and cement mortar or cement paste of less than 8 mm. If the amount of recovered coarse aggregate obtained does not reach the expected amount, or if the cement mortar or cement paste is not sufficiently peeled off, the recycled coarse aggregate of 8 mm or more is again applied to the G grinder and processed in the same manner. .

  Although there are various types of G grinders as described above, there is no particular limitation. A preferable example is TRAS (trade name) developed by Taiheiyo Cement Group using a screw-type grinding method. TRAS has a grinding processing unit called twin cone that mechanically grinds the lump of raw material, and adjusts the flow rate of the lump, while giving the lump an appropriate grinding action. The cement paste is destroyed with a force that does not break A lump of raw material (crushed material of 40 mm or less) charged into TRAS is conveyed from the charging hopper to the vibrating screen by a belt conveyor, where less than 8 mm is screened off. Next, after grinding with a twin corn to remove the cement paste, it is transported again to a vibrating screen and screened for less than 8 mm. The case where the twin corn and vibrating sieve processes are processed once and discharged is set as a single process, and the process repeated twice is set as a double process. Although the quality of the recycled coarse aggregate obtained by increasing the number of treatments can be improved, the amount of fine particles / fine powder increases as the number of treatments increases. One of the features of TRAS is that the quality of recycled coarse aggregate and the amount of fine particles / fine powder generated can be controlled by selecting the number of treatments as described above. Therefore, in the present invention that requires control of the quality of the recycled coarse aggregate and the amount of by-product fines, it is a preferred processor for producing coarse aggregate.

  For example, when the recycled coarse aggregate is manufactured by TRAS, the crude aggregate is collected at a collection ratio of 40 to 60% by one or two processes based on past results. The quality of the recycled coarse aggregate is mostly recycled coarse aggregate M defined in Appendix A of JIS standard A5022, but some of the recycled coarse aggregate H slightly exceeds the JIS standard value of recycled coarse aggregate H. Some of them are classified as “recycled coarse aggregate L” slightly below the JIS standard value of the recycled coarse aggregate M. Table 1 shows an example of the recovery rate and the quality of the recycled coarse aggregate when the recycled coarse aggregate is manufactured by TRAS.

  Fine particles of less than 8 mm that have been screened off by a vibrating sieve are ground with an S grinder to peel off the cement paste that is primarily attached to the fine aggregate. Then, the treated product is passed through a vibration sieve and classified at 0.15 mm, and is divided into by-product fine powder mainly composed of recycled fine aggregate of 0.15 mm or more and cement paste of less than 0.15 mm. If the recovered amount of the regenerated fine aggregate does not reach the expected amount or if the cement paste is not sufficiently peeled off, the regenerated fine aggregate of 0.15 mm or more is again subjected to the S grinder and processed in the same manner. To do. As in the case of TRAS, the process is performed once, and the process is performed twice.

  There are various types of S grinders as described above, but they are not particularly limited. A preferred example is a KM polisher (trade name) manufactured by Kansai Matec Co., Ltd. using a mechanical grinding method. The KM polisher can round the grains with relatively weak grinding, and has a track record in improving the shape of the foundry sand. There is a roller that freely rotates in the drum, and the charged fine particles are subjected to a scuffing action between the drum and the roller, and the cement paste that is attached to the fine aggregate is peeled off. Similar to the above TRAS, the quality of the regenerated fine aggregate obtained by increasing the number of treatments can be improved, but the amount of by-product fine powder increases as the number of treatments increases. Even by the KM polisher, the quality of the regenerated fine aggregate and the amount of by-product fine powder generated can be controlled by selecting the number of treatments as described above. Therefore, in the present invention where it is necessary to control the quality of the regenerated fine aggregate and the amount of by-product fine powder, the mill is suitable for producing fine aggregate.

  For example, when reclaimed fine aggregate is manufactured by KM polisher following TRAS, according to past results, fine aggregate is recovered at a recovery rate of 25 to 40% in one or two processes. The quality of the recycled fine aggregate is mostly the recycled fine aggregate M defined in Appendix A of JIS standard A5022, but some of the recycled fine aggregate L is slightly below the JIS standard value of the recycled fine aggregate M. Some are classified as: Table 2 shows the recovery rate and quality example of the recycled fine aggregate when the recycled fine aggregate is manufactured by the KM polisher.

  As described above, if TRAS is used as the G grinder and KM polisher is used as the S grinder, the recovery rate and the amount of by-product fines can be controlled by the number of treatments. Adjusting the recovery rate according to the mixing ratio of recycled coarse aggregate, recycled fine aggregate, and by-product fine powder, or adjusting the amount of by-product fine powder to a predetermined amount can be adjusted mainly by the number of treatments. The object of the invention can be suitably achieved. Table 3 shows an example of the recovery ratio of recycled material from waste concrete. The recovery ratio is a value obtained from the volume ratio of the recovered recycled material.

<Manufacturing method of recycled concrete>
The flowchart which shows the manufacturing process of the manufacturing method of the recycled concrete of this invention is shown in FIG.

In the production method of the present invention, recycled concrete is produced using the total amount of recycled coarse aggregate, recycled fine aggregate, and by-product fine powder obtained by the above-described waste concrete processing method of the present invention. If the recycled coarse aggregate produced alone cannot produce coarse aggregate with an appropriate particle size distribution as concrete coarse aggregate, or the production volume of recycled fine aggregate and by-product fine powder will be larger than the index. When the amount of recycled coarse aggregate is less than the amount used as an index, as described above, an adjusting stone having an appropriate particle size range may be added. The recycled fine aggregate is mixed with by-product fine powder in an amount of 20% by weight or less of the total amount of fine aggregate. In the case where the particle size of the produced recycled fine aggregate is not suitable for the particle size as the fine aggregate for concrete, or when the recycled coarse aggregate or by-product fine powder is produced in a proportion higher than the index, as described above, Adjustment sand is mixed if necessary. The particle size distribution of the coarse aggregate and the fine aggregate is preferably the particle size distribution defined in Annex A of JIS standard A5022, but the particle size of the regenerated coarse aggregate, regenerated fine aggregate and by-product fine powder obtained as a regenerated material Since the distribution is not constant, the lack of particle size range can be compensated by adjusting stones and adjusting sand.

  The remaining by-product fine powder used as a part of the fine aggregate is used as a part of the cement raw material and recovered as Portland cement. The amount added to the cement raw material is preferably 10% by weight or less from the viewpoint of ensuring the quality of cement and the stability of production. Next, production of cement will be described.

[Manufacture of cement]
Cement is generally made by mixing and pulverizing cement raw materials made of limestone, clay, silica, iron oxide raw materials, etc. in a raw material process raw material mill, preliminarily firing the pulverized raw materials in a preheater, and sending them to a rotary kiln. The cement clinker is obtained by firing at a high temperature, and gypsum is added to the cement clinker in the finishing step and mixed and pulverized. By-product fine powder added to cement raw materials is added mainly as a substitute for clay. The amount of by-product fine powder added was 100 kg per ton of cement to be produced.

  After the by-product fine powder to be added is dried, a chemical component is quantitatively analyzed by a fluorescent X-ray analyzer. Based on the results, the materials used and the composition of the cement material are selected. Selection is made using the Borg formula so that alite, belite, ferrite phase, and aluminate phase have the same constant ratio as Portland cement. The raw materials are prepared based on the above formulation, the mixed raw materials are mixed and pulverized with a ball mill or the like, and granulated into a predetermined particle size range with a pan pelletizer. The obtained granulated material is fired in a rotary kiln to obtain a cement clinker (Portland cement clinker). The firing conditions are the same as the conditions for firing the Portland cement clinker. Gypsum is added to the obtained cement clinker to the same extent as conventional Portland cement and mixed and pulverized to obtain a cement according to the present invention (hereinafter referred to as “trial cement”). An example of quality is shown.

  Recycled concrete of the present invention recycles the above coarse aggregate, fine aggregate, trial cement, chemical admixture such as high performance water reducing agent used as needed, cement admixture such as fly ash, and kneaded water Manufactured based on concrete mix design. Each material is weighed and kneaded with a concrete mixer. A manufacturing apparatus such as a concrete mixer may be a conventional apparatus, and a manufacturing method other than the above may be performed by a conventional method.

<Recycled concrete>
The recycled concrete of the present invention can be obtained by the above-described production method using the entire amount of recycled material obtained from waste concrete, and comprises a coarse aggregate composed of recycled coarse aggregate and adjusting stone added as necessary, and recycled fine particles. Fine aggregate consisting of aggregate, by-product fine powder and adjusted sand added if necessary, trial cement with cement clinker obtained from cement raw material partially containing the by-product fine powder, and added as necessary It consists of a chemical admixture such as a high performance water reducing agent and / or a cement admixture such as fly ash.

  Moreover, the volume of the recycled concrete of this invention is 3.5 times or less of the volume of the waste concrete used as the starting material of a recycled material. Compared to conventional recycled concrete (recycled coarse aggregate, recycled fine aggregate, or concrete by reusing at least one by-product fine powder), the volume of by-product fine powder was reduced in this way. This is due to the fact that the content is 15 to 25% by weight, and the by-product fine powder is used as a substitute for fine aggregates or a cement raw material.

  Further, when the main coarse aggregate is a recycled coarse aggregate defined in Annex A of JIS standard A5022, and the main fine aggregate is a recycled fine aggregate defined in Appendix A of JIS standard A5022, the reproduction of the present invention is performed. Concrete has fresh properties, strength properties and durability that are practical in the civil engineering and construction fields. The performance confirmation test of the trial recycled concrete is shown below.

[Performance confirmation test of recycled concrete]
(1) Manufacture of recycled concrete

A. Materials used Water (symbol; W) Tap water Cement (symbol; C) Table 4 obtained by adding 10% by weight of by-product fine powder to cement raw material
Prototype cement (density; 3.19 g / cm 3)
Cement admixture (symbol: FA) Fly ash type 2 (manufactured by J-Peck)
Fine aggregate (symbol: SL) Product processed once with KM polisher (Recycled fine of JIS standard)
Aggregate M equivalent) + 20% by-product fines (internal split)
(Symbol: SH) Product treated twice with KM polisher (recycled JIS standard)
Aggregate M equivalent) + 20% by-product fines (internal split)
(Symbol: S) Crushed sand from Fukushima Coarse aggregate (symbol: GL) Reprocessed coarse bone of JIS standard ...
Material M equivalent
(Symbol: GH) Reprocessed product of JIS standard ...
Material M equivalent
(Symbol: G) Fukushima Prefecture Crushed Stone 2005
Chemical admixture
Air amount adjusting agent (symbol: AE) manufactured by BASF Pozoris Bussan Co., Ltd., Micro Air 101

B. Table 5 shows the mix of recycled concrete. Formulation is 60% water / powder ratio (W / P; cement + fly ash), unit water quantity 165kg, unit cement quantity 264k.
g, the unit fly ash amount (20% of the total powder amount) is fixed, and the target slump (12
The fine aggregate ratio and the amount of admixture were adjusted so as to be within the range of ± 2.5 cm) and the amount of air (4.5 ± 1.5%).
Fly ash is mixed to suppress the alkali silica reactivity of recycled aggregate. JIS standard A5022 (recycled aggregate for concrete M) Annex C defines five categories of measures to suppress alkali silica reactivity.
In this confirmation test, one of the five measures, “Suppression Measures that Use Mixed Cement with Alkali Silica Reaction Suppression Effect and Restrict the Upper Limit of Unit Cement” was adopted. Specifically, fly ash cement (fly ash + cement)
The upper limit of the unit amount was 350 kg / m 3 or less, and the fly ash content (fly ash / fly ash + cement) was 20% or more.

In Table 5, compounding No. 1 and No. 2 is a recycled concrete of an embodiment of the present invention,
Compound No. 3 is a normal concrete of a comparative example.

C. Kneading of recycled concrete Each of the blended materials was kneaded and manufactured under the above blending conditions such that the entire amount of recycled material from waste concrete was used.

(2) Test level A performance test was performed on the test levels indicated by symbols shown in Table 5.
Table 6 shows an example of the relationship between the ratio of recycled materials in recycled concrete and their recovery ratio.

  (3) Test items and test methods

A. Fresh properties a) Slump
Conforms to JIS A 1101 “Concrete slump test method”.
b) Air volume
JIS A 1128 “Fresh concrete air pressure test
Method (air chamber pressure method) ”.
c) Bleeding
Conforms to JIS A 1123 “Concrete Bleeding Test Method”
It was.

B. Volume ratio
Recycled concrete body for waste concrete used as starting material for recycled material
The product ratio was obtained by calculation based on the recovery ratio and the recipe.

C. Strength properties a) Compressive strength
Conforms to JIS A 1108 “Concrete compressive strength test method”. Measurement
The standard material age is 7, 28 days, and the curing method is standard curing (2
Underwater curing at 0 ° C.).
b) Static elastic modulus
Conforms to JIS A 1149 “Testing method for static elastic modulus of concrete”.
The measurement material age was 28 days, and the curing method was standard curing (water curing at 20 ° C.) after demolding on the first day of the material age.

D. Durability a) Freeze-thaw
Conforms to JIS A 1148 “Method A for Freezing and Thawing Concrete”
It was. The measurement start date is 28 days, and the curing method is measured after demolding on the first day.
Standard curing (water curing at 20 ° C.) was used until the beginning.
b) Length change
JIS A 1129-2 “Length change test method of mortar and concrete
-Conforms to "Part 2 Contact Gauge Method". Curing method is demolding in 1 day of material age
It was set as standard curing (water curing at 20 ° C.) from later until the start of measurement. Measurement start age
Is 28 days, and after the start of measurement, the temperature is 20 ± 2 ° C. and the relative humidity is 60 ± 5%.
It left still in the humidity chamber. Measurement material after the start of measurement based on the 28th day
The decree was 7, 28, 56, 91, 182 days.
c) Promoting neutralization
This was in accordance with JIS A 1153 “Testing method for accelerated neutralization of concrete”.
The curing method is standard curing (after water removal at 20 ° C from 28 days after demolding at 1 day of material age)
Curing), and then constant temperature of 20 ± 2 ° C and relative humidity of 60 ± 5% until 56 days after material age
It left still in a constant humidity room. Then, temperature 20 ± 2 ° C, relative humidity 60 ± 5%,
Started neutralization promotion curing in a constant temperature and humidity chamber with a carbon oxide concentration of 5 ± 0.2%.
It was.
The measurement material age was 7, 28, 56, 91 days after the start of neutralization promotion curing.

(4) Test results A. Fresh properties B. Volume ratio Table 7 shows the test results of the fresh properties and the calculated value of the volume ratio (see calculation examples described later).

  In the recycled concrete (No. 1 to No. 2) of the present invention, the slump and the air amount were within the target range by adjusting the fine aggregate ratio and the amount of the chemical admixture. Further, considering that the amount of the chemical admixture used is the same, the recycled concrete of the present invention can be handled in the same manner as ordinary concrete when adjusting the slump and air amount of recycled concrete.

  Bleeding rate indicates material separation of fresh concrete and is known as a phenomenon indicating the possibility of generating initial defects such as cold joints and settlement cracks. Therefore, a smaller bleeding rate is preferable from the viewpoint of durability. The recycled concrete of the present invention had a freezing rate smaller than that of ordinary concrete (No. 3). Moreover, the volume ratio with respect to the waste concrete used as the starting material of the recycled material is 3.5 or less in any case, and the production amount of recycled concrete does not increase remarkably even if the entire amount of recycled material such as by-product fine powder is used.

C. Strength properties Table 8 shows the test results of strength properties.

  As mentioned above, the strength properties of the recycled concrete (No.1 to No.2) of the present invention in which all aggregates including by-product fines are recycled aggregates are No.1 compared to No.3 of ordinary concrete. The result is 92% and No. 2 is 86%, which is a concrete that can sufficiently exhibit practical strength in the fields of civil engineering and architecture.

D. Durability Table 9 shows the results of the freeze-thaw test.

The freeze-thaw durability index (relative dynamic elastic modulus) of the recycled concrete of the present invention (No.1 to No.2) using the total amount of recycled material is 74% for No.1 and 61% for No.2. It is slightly smaller than 88% of ordinary concrete. This is a common tendency of recycled aggregates, because old building concrete often does not use air-binding agents, and is unavoidable. However, because it has also passed the rules (relative kinematic elastic modulus 60% or more) established by JASS5 of the Architectural Institute of Japan (standards for building construction standards and explanations), civil engineering also from the viewpoint of resistance to freezing and thawing. And it can be sufficiently put into practical use as concrete used in each field of architecture.
Next, Table 10 shows the result of the length change test of recycled concrete.

The length change after 182 days of the recycled concrete of the present invention (No. 1 to No. 2) using the total amount of recycled material is 770 × 10 −6 or less for both No. 1 and No. 2 and ordinary concrete It is slightly larger than No.3 which is 517 × 10−6. However, the rules stipulated in JASS5 of the Architectural Institute of Japan (standards for building construction and explanation) (800 x 10-6 or less in 6 months) and the standards stipulated in the concrete standard specification of the Japan Society of Civil Engineers ( Since it has passed 1000 × 10 −6 or less in 6 months, it can be sufficiently put into practical use as a concrete used in each field of civil engineering and architecture even in terms of length change.
The results of the accelerated neutralization test are shown in Table 11.

  The accelerated neutralization depth after 91 days of the recycled concrete of the present invention (N0.1 to No. 2) using the total amount of recycled material is 28 mm for both No. 1 and No. 2, Compared with 24.5 mm of .3, there was no significant difference. Therefore, even from the point of resistance to neutralization, it can be sufficiently put into practical use as concrete used in each field of civil engineering and architecture.

  As described above, the durability of the recycled concrete (N0.1 to No. 2) of the present invention was slightly inferior to that of ordinary concrete (No. 3), but its absolute value is a problem in terms of durability. There was no value.

  As can be seen from the above specific example, concrete having practical performance can be obtained by using the whole amount from waste concrete and without significantly increasing the volume (recycled amount) of newly produced recycled concrete as in the past. The significance of this is great.

Below, the calculation example of the volume ratio in the mixing | blending No. 2 of Table 7 is shown as reference.
[Example of volume ratio calculation]
Table 12 shows the basic concrete composition of composition No. 2 in the above examples.

  Table 13 shows the practical blend of recycled concrete according to blend No. 2. All the recycled materials were used, but adjusted sand and adjusted stone were also used.

Although it was designed based on the by-product fine powder, the by-product fine was generated based on the amount of the by-product derivative, but it is possible to use all of the recycled material by using this whole amount. It is. Here, since all the by-product fine powder was used, the fine powder amount was the same as in Table 12, and the air amount, water amount, cement amount, and fly ash amount were also the same. The amount of recycled fine aggregate and the amount of recycled coarse aggregate were determined by calculation from the amount of fine powder and the recovery ratio in Table 6.

  As shown in Table 13, the amount of recycled material contained in recycled concrete, that is, the total volume of by-product fine powder (fine aggregate replacement and cement raw material), recycled fine aggregate, and recycled coarse aggregate is 479.5 liters. It is. Since the volume of recycled material contained in 1000 liters of recycled concrete (corresponding to the volume of waste concrete) is 479.5 liters, it is recycled to the waste concrete (more precisely, the total volume of recycled materials) that was the starting material for recycled materials. The volume ratio of concrete is 2.1 times.

Claims (2)

Medium quality recycled coarse aggregate defined in Annex A of JIS standard A5022, obtained by processing waste concrete from demolition concrete, recycled fine aggregate defined in Appendix A of JIS standard A5022. the quality of the reproduced fine aggregate in the M, with the total amount of the recycled material consisting of by-product fines generated when obtaining the reproduction fine aggregate, one or the waste volume of the playback concrete to be produced as a starting material A method for producing recycled concrete in which the volume of concrete is 3.5 times or less , wherein in the recycled concrete, the by-product fine powder is 10 to 25% by weight of the waste concrete, and the main coarse aggregate is The regenerated coarse aggregate (A), the main fine aggregate is the fine aggregate (B) containing 20% by weight or less of the regenerated fine aggregate and the by-product fine powder, and the cement is the fine aggregate For mixing A cement (C) produced using a cement clinker obtained by firing a cement raw material containing 10% by weight or less of the by-product fine powder outside, and the recycled material of these (A) to (C) as a main material A method for producing recycled concrete, comprising producing concrete. The recycled concrete uses the recycled coarse aggregate M having a recovery ratio of 40 to 60% and the recycled fine aggregate M having a recovery ratio of 25 to 40% with respect to the waste concrete. Recycled coarse aggregate M, recycled fine aggregate M, and by-product fine powder mixing ratios are equal to the recycled coarse aggregate M, recycled fine aggregate M, and by-product fine powder recovery ratios. The method for producing recycled concrete according to claim 1, wherein:

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