JP2005111675A - Method of manufacturing ready-mixed concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture ready-mixed concrete good in workability by crushing a concrete structure by an impact type crusher under a predetermined operation condition to use the obtained crushed matter as aggregate for ready-mixed concrete. <P>SOLUTION: A concreat structure is crushed under a proper operation condition by a crusher and the obtained crushed matter is used as aggregate to manufacture the ready-mixed concrete comprising kneaded matter of the aggregate, water and cement while the evaluated value of the workability of the ready-mixed concrete is measured to be compared with the evaluation value of workability necessary as concrete to be cast. When the evaluation value of the workability of the ready-mixed concrete does not enter the range of the evaluation value, the operation condition of the crusher is altered to use the crushed matter obtained under the operation condition as aggregate to manufacture the ready-mixed concrete having good workability. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing ready-mixed concrete using a crushed material obtained by crushing an existing concrete structure with a striking crusher as an aggregate.

  In recent years, from the viewpoint of effective use of resources, a part of existing concrete structure is crushed by a blow-type crusher such as a chipper or a breaker, and all fine and coarse parts obtained by crushing are made of raw concrete bone. It is proposed to be used as a material and is being put into practical use. For example, only the aged part of the concrete at the bottom of an existing canal tunnel is sown, and the crushed material, which is crushed, is used as an aggregate to knead the ready-mixed concrete with water and cement. It is becoming practical to place this ready-mixed concrete on the bottom of the tunnel from which the above-mentioned aging part has been peeled off.

  On the other hand, when the entire amount of crushed material from fine to coarse particles of an existing concrete structure is used as the aggregate of ready-mixed concrete, the existing concrete structure is first disassembled and subdivided into concrete blocks. It has been practiced to crush the resulting concrete lump from two directions with a crusher such as a jaw crusher, a cone crusher, or a roll crusher to obtain a crushed material having a particle size suitable as an aggregate for ready-mixed concrete. In this case, it is said that the particle size of the crushed material is not significantly affected by the operating conditions of the crusher and the strength of the concrete block.

JP 2001-130944 A

  However, when crushing a part of a concrete structure with a blow-type crusher such as the above chipper or breaker as in the former, the crushing mechanism uses a crushing blade (crushing bit) whose tip is formed at a sharp end. Compressive failure around the crushing blade due to biting of the crushing blade when hitting the concrete lump in one direction, and planar tensile failure occurring in the concrete portion between two adjacent crushing blades These compression fractures and tensile fractures are easily affected by the strength of the concrete, and the operating conditions of the crusher, that is, the impact force per crushing blade, the crushing blade mounting interval, Since the ratio of compression failure to tensile failure changes greatly depending on the distance of the crushing blade to the next crushing position, etc. Susceptible to the influence of the intensity of the operating conditions and concrete.

  Therefore, unlike the crushed material obtained by crushing from the above two directions, it is difficult for the concrete crushed material crushed by impact to fall within a predetermined particle size distribution suitable as an aggregate for ready-mixed concrete. In the case of preparing ready-mixed concrete by kneading this crushed material with water and cement as an aggregate, there is a problem in that workability is hindered.

  The present invention has been made in view of the above problems, and uses a crushed material obtained by crushing an existing concrete structure with a striking crusher as an aggregate for ready-mixed concrete. It is in providing the manufacturing method of the ready-mixed concrete for the purpose of manufacturing ready-made ready-made concrete.

  In order to achieve the above object, a method for producing ready-mixed concrete according to claim 1 of the present invention provides a crushed material obtained by crushing an existing concrete structure by hitting with a crusher having a plurality of crushing blades. A method for producing ready-mixed concrete used as an aggregate, wherein a predetermined concrete is to be casted with crushed material, water and cement of an existing concrete structure crushed by operating the crusher under certain operating conditions. Based on this comparison, the evaluation value of the workability of ready-mixed concrete kneaded at the blending ratio is detected, and the evaluation value of the workability is compared with the evaluation value of the workability required for the concrete to be placed. Therefore, the workability evaluation value of the above-mentioned ready-mixed concrete should be increased to the workability evaluation value required for the concrete to be placed. And adjusting the operating conditions of the crusher.

  In the method for producing ready-mixed concrete according to claim 1, the operating condition of the crusher is, as described in claim 2, the striking force per crushing blade, the crushing blade mounting interval, or the crushing blade The operating conditions are determined so that the aggregate particle size distribution required for the concrete to be placed is changed by changing at least one of these conditions. It is characterized by adjusting.

  Furthermore, the invention according to claim 3 changes the impact force per crushing blade of the crusher and the crushing blade mounting interval by changing the number of crushing blades installed within a fixed crushing blade mounting area. It is characterized by that.

  Further, in the method for producing ready-mixed concrete according to claim 1, the evaluation value of workability is the slump value, the slump flow value, the crushed material, water and cement of the ready-mixed concrete as described in claim 4. The rotation resistance value of the mixer or the surface change of the kneaded material is one of the characteristics.

  According to the method for producing ready-mixed concrete of the present invention, an existing concrete structure is crushed by operating a crusher under a certain operating condition, and the crushed material, aggregate and water are kneaded at a predetermined blending ratio. The ready-mixed concrete is prepared and the evaluation value of the workability of the ready-mixed concrete is detected, and the evaluation value of the workability is compared with the evaluation value of the workability required for the concrete to be placed. Since the operating conditions of the crusher are adjusted so that the workability evaluation value of the ready-mixed concrete becomes the workability evaluation value required for the concrete to be placed, the existing concrete structure is crushed. It can be crushed into a crushed material having a particle size distribution suitable as an aggregate for ready-mixed concrete by the impact force of the machine, and this aggregate Mixed concrete to exhibit excellent workability properties by kneading cement and water in which it is possible to be efficiently manufactured.

  Therefore, water and cement are kneaded in situ on the ground using the concrete crushed material obtained by smashing the existing concrete structure such as the bottom of an aging existing tunnel with the impact of the crushing machine. It is possible to perform the repair work of the tunnel accurately and efficiently by placing it on the beveled surface such as the bottom of the tunnel while producing the ready-made ready-mixed concrete.

  Furthermore, according to the invention according to claim 2, the operating condition of the crusher is determined by the striking force per crushing blade and the crushing blade mounting interval, or the movement distance of the crushing blade to the next crushing position. The operation condition is adjusted so as to obtain the aggregate particle size distribution required for the concrete to be placed by changing at least one of these conditions. It can be carried out easily and accurately, and a concrete crushed material that falls within a desired particle size range can be produced.

  Moreover, according to the invention which concerns on Claim 3, the change of the impact power per crushing blade of a crusher and the attachment space | interval of a crushing blade is changed by changing the number of crushing blades attached within a fixed crushing blade installation area. Since it is to be done, by configuring in advance a plurality of crushing blades that can be mounted at regular intervals, the crushing blade mounting interval can be easily changed according to the strength of the concrete structure to be crushed It is possible to adjust the striking force per crushing blade to a large or small value. Therefore, a crushed concrete having a grain size suitable as an aggregate for ready-mixed concrete can be obtained by the impact force of the crushing blade as described above.

  In the method for producing ready-mixed concrete, the evaluation value of workability is the slump value of ready-made concrete made of a kneaded mixture of concrete crushed material, water and cement obtained by a crusher, or slump as described in claim 4. It can be easily detected from any one of the flow value, the rotational resistance value of the mixer for kneading the crushed material, water and cement, or the surface change of the kneaded material.

  Next, a specific embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a striking crusher A in which two crushing blades 1 and 1 are provided on the lower end surface so as to project downward in parallel with each other. The crushing blade 1 is composed of a crushing bit having a small-diameter short column shape with a lower end (tip) formed at a tapered sharp end. It is a detachable attachment to the lower end surface of the crusher A with a desired interval in the orthogonal direction. Furthermore, this crusher A has operating conditions such as the percussion force per crushing blade 1, the mounting interval of the crushing blade 1, or the movement distance of the crushing blade 1 to the next crushing position. It can be changed to large or small.

  And, in order to obtain a crushed concrete having a particle size distribution suitable for this crusher A as an aggregate for ready-mixed concrete, in other words, a ready-mixed concrete worker obtained by using this crushed as an aggregate. The above operating conditions are adjusted so that the evaluation value of workability becomes the evaluation value of workability required for the concrete to be placed, and under this adjusted operating condition, a part of the existing concrete structure such as the tunnel bottom is adjusted. The crushed material, water and cement are kneaded to produce ready-mixed concrete with good workability.

  In this way, a method for obtaining an aggregate having a particle size distribution required for concrete to be placed by crushing a part of an existing concrete structure after adjusting the operating conditions of the crusher A will be described in more detail. Although there is no clear regulation regarding the particle size and maximum size of aggregates made from crushed concrete used for ready-mixed concrete, the particle size is determined by the workability and quality of ready-mixed concrete, and the desired particle size distribution for ready-mixed aggregate It is preferable that the aggregate having a predetermined range of particle size is appropriately mixed with large and small particles without being biased to a specific particle size. If there is a large proportion of aggregates for large diameters, material separation tends to occur and the workability of ready-mixed concrete decreases, that is, workability deteriorates. This is because the drying shrinkage of the resin becomes large and cracks are likely to occur, and the quality deteriorates.

Considering the mechanism of the destruction of the existing concrete structure by the blow-type crusher A, first, in FIG. 1, the distance between the two crushing blades 1 and 1 is a, the existing per one blow. The biting depth of the crushing blade with respect to the concrete structure is b, the moving distance of the crushing blade to the next crushing position is c, the strength of the existing concrete structure is d, and the size of the crushing material is e. On the other hand, as the crushing mechanism of the existing concrete structure by hitting the crushing blade 1, the following three can be considered.
1) Concrete is crushed by the crushing force of the blade edge of the crushing blade (compression failure)
2) Concrete is crushed by pulling between the two crushing blades due to the biting of the two crushing blades (tensile failure)
3) A combination of 1) and 2) above.

  The compression fracture and the tensile fracture will be described. As shown in FIG. 2 (a), when the cutting edge of the crushing blade 1 starts to bite into the surface of the existing concrete structure C, a crack is generated in the surface layer portion of the concrete structure C. When this occurs and the cutting edge further bites in, the surface layer portion of the concrete structure C around the cutting edge is destroyed by the crushing force of the cutting edge as shown in FIG. As the cracks are generated, the cracks are generated deeper and the tensile force generated on the concrete surface between the crushing blades 1 and 1 is increased. As shown in (c), the concrete portion between the crushing blades 1 and 1 is broken to produce an aggregate C2 having a large particle size.

  Thus, when an existing concrete structure is crushed by the compressive fracture of 1), a crushed material (aggregate C1) having a relatively small size compared to the tensile fracture of 2) is generated. In the case of this compressive fracture, if the biting depth b of the crushing blade 1 is large, the size e of the crushed material obtained becomes large. Further, when the impact pressure of the crushing blade 1 is constant, the penetration depth b is inversely proportional to the strength d of the existing concrete structure C, whereas when the strength d of the existing concrete structure C is constant, the penetration depth b. The length b is proportional to the impact pressure. Further, in the case of hitting a plurality of crushing blades 1 with a constant pressure, the impact pressure per crushing blade is changed by changing the number of crushing blades 1 mounted within a certain size on the lower surface of the crusher A. Can do. That is, the impact pressure per crushing blade increases as the number of crushing blades 1 attached increases. FIG. 3 shows the relationship between the number of crushing blades 1 and the dimension e of the crushed material (aggregate C1).

  Next, the case where the existing concrete structure is crushed by the tensile fracture of 2) will be described. In this case, a crushed material (aggregate C2) having a relatively large size is generated as described above, but the maximum bit interval at which the existing concrete portion between the crushed blades 1 and 1 is crushed (= the maximum size of the crushed material). ) Relates to the strength d of the existing concrete C. That is, as shown in FIG. 4, when the strength d of the existing concrete C is small, the maximum crushing blade interval a1 at which the concrete portion between the crushing blades is crushed becomes large, and when the strength d of the existing concrete C is large. The maximum crushing blade interval a1 is reduced. Furthermore, if the crushing blade interval is too large, that is, if the interval a1 is exceeded, the concrete portion between the crushing blades will not be crushed, and the maximum size of the crushed material will be reduced. Therefore, the relationship as shown in FIG. 4 is established between the interval a between the crushing blades and the dimension e of the crushed material.

  In the case of the combination of the compressive fracture of 1) and the tensile fracture of 2), as shown in FIG. 5 (a), if the moving distance c1 to the next striking position of the crushing blade 1 is longer than the crushing blade interval a Secondary crushing does not occur, and the size e of the crushed material remains the sum of the compression fracture of 1) and the tensile fracture of 2). On the other hand, as shown in FIG. 5 (b), if the moving distance c2 to the next striking position of the crushing blade 1 is shorter than the crushing blade interval a, the above 2) a relatively large-diameter crushed material obtained by tensile fracture Will be crushed again (secondary crushing), and the dimension e of the crushed material will be small. When the existing concrete C is crushed while the crushing blade sequentially moves with a constant moving distance, the dimension e of the crushed material becomes smaller as the moving distance c is shorter.

  From the above, the factors that affect the particle size of the crushed material are the strength d of the existing concrete structure C to be crushed, the impact pressure of the crushing blade 1, the mounting interval a of the crushing blade 1, and the crushing blade 1 The moving distance c. Here, when the number of the crushing blades 1 is reduced as a means for increasing the impact pressure of the crushing blades 1, as described above, the attachment interval a of the crushing blades 1 tends to be widened, and the size of the crushed material tends to increase. When the number of crushing blades 1 is reduced, the size of the crushed material tends to be reduced. Although this tendency is qualitative, it is difficult to quantitatively grasp in advance. Furthermore, the size of the crushed material also varies depending on the shape and size of the crushing blade of the crusher A, and also varies depending on the number of hits at one place.

  And in embodiment of this invention, the operating condition which is a factor influencing the particle size of the said crushed material of this crusher A is adjusted, the existing concrete structure C is crushed, and the crushed material is made into ready-mixed concrete. By using the aggregate, water and cement as kneading aggregates, a ready-mixed concrete having a desired good workability is produced.

  Next, a specific example of this method for producing ready-mixed concrete will be described based on the flowchart of FIG. First, an existing concrete structure is beaten with the operating conditions of the crusher A set appropriately, and the total amount of the obtained crushed material is used as an aggregate, and this aggregate is put into a mixer together with water and cement and kneaded. After making ready-mixed concrete, the workability evaluation value of this ready-made concrete is measured.

  As a concrete method for detecting the evaluation value of ready-mixed concrete workability, that is, whether the workability is good or bad, a method of measuring a slump value, which is an index indicating the degree of softness (fluidity) of ready-mixed concrete, and its slump A method for measuring the flow value, a method for detecting the rotational resistance value of a mixer for kneading crushed material, water and cement, or if the kneaded material has poor fluidity, the degree of unevenness on the surface increases and the fluidity If the thickness is good, the degree of unevenness of the surface becomes small. Therefore, there is a method of detecting the surface change of the kneaded material with a light wave distance meter, an ultrasonic distance meter or the like, and at least one of these methods may be adopted.

  Next, compare the measured evaluation value of ready-mixed concrete in the mixer with the evaluation value of workability required for the concrete to be placed in advance. If the evaluation value is within the range of the workability evaluation value required for the concrete to be placed, the above concrete crushing having a predetermined particle size distribution is obtained by rolling the existing concrete structure according to the set operating conditions. A thing is obtained and the said ready-mixed concrete which uses this as an aggregate is manufactured.

  On the other hand, if the measured value of the ready-mixed concrete workability is outside the range of the workability evaluation value required for the concrete to be placed, the operating condition of the crusher A is changed to replace the existing concrete structure. The particle size distribution of the crushed material obtained by crushing is changed, and the crushed material is put into the mixer together with water and cement as aggregate, and ready-mixed concrete is produced by kneading. At this time, from the measured value of the ready-mixed concrete workability, for example, it can be determined whether the ready-mixed concrete has poorer or better fluidity than the required ready-mixed concrete. The operating conditions of the crusher A are changed so that the workability evaluation value of the obtained ready-mixed concrete falls within the range of the workability evaluation value required for the concrete to be placed.

  Specifically, in the workability evaluation value X required for the concrete to be placed, the slump value is X1, the slump flow value is X2, the rotation resistance value of the mixer is X3, and the roughness of the surface of the kneaded material is In the evaluation value x of workability of the ready-mixed concrete manufactured in the mixer, the slump value is x1, the slump flow value is x2, the rotation resistance value of the mixer is x3, and the unevenness of the surface of the kneaded material is x4. When it is determined that the large particle size distribution of the crushed material crushed by the crusher A is exceeded, x1> X1, x2> X2, x3 <X3, x4 <X4. X1 <X1, x2 <X2, x3> X3, x4> X4.

  Therefore, when it is determined that the large diameter is exceeded in the particle size distribution of the crushed material crushed by the crusher A, the moving distance (crushing pitch) of the crushing blade 1 is shortened or the impact pressure is reduced. Or shorten the distance between the crushing blades. At this time, adjustment is performed by changing at least one of these three operating conditions. Also, if it is determined that the crushed material exceeds the small diameter as aggregate, conversely, whether the moving distance (crushing pitch) of the crushing blade 1 is increased or the impact pressure is increased. Increase the distance between the crushing blades. Also in this case, adjustment is made by changing at least one of these three operating conditions.

  After changing the operating conditions in this way, the existing concrete structure was again smashed by the crusher A, and the aggregate was put into the mixer together with water and cement using the total amount of the crushed material obtained as an aggregate. After preparing ready-mixed concrete by kneading, the evaluation value of the workability of this ready-mixed concrete is measured. Then, this workability evaluation value is compared with the workability evaluation value required for the concrete to be placed, and the measured workability evaluation value of the ready-mixed concrete is the workability required for the concrete to be placed. If the existing concrete structure is beaten under the changed operating conditions, the concrete crushed material having a predetermined particle size distribution is obtained, and the ready-mixed concrete using the aggregate is used as an aggregate. To manufacture. If the measured value of the ready-mixed concrete workability is outside the range of the workability evaluation value required for the concrete to be placed, the operating conditions of the crusher A are changed in the same manner as described above, It is adjusted so that ready-mixed concrete having workability characteristics can be manufactured.

  According to this aggregate manufacturing method, the striking pressure of the crushing blade 1 is changed as the operating condition of the crusher A. However, the striking pressure is constant (invariable) and the moving distance and the distance between the crushing blades are changed. By doing so, you may make it manufacture the aggregate in the particle size distribution range which can obtain the ready-mixed concrete which has predetermined | prescribed workability.

  FIG. 7 is a flowchart showing the method for producing ready-mixed concrete. First, in the same manner as the method for manufacturing ready-mixed concrete shown in FIG. 6, the existing concrete structure is set with the operating conditions of the crusher A appropriately set. The total amount of the crushed material obtained, and the aggregate as the aggregate were put into a mixer with water and cement and kneaded to prepare ready-mixed concrete. It measures using the method described in the manufacturing method of the ready-mixed concrete of the said FIG.

  Next, compare the measured evaluation value of ready-mixed concrete in the mixer with the evaluation value of workability required for the concrete to be placed in advance. If the evaluation value is within the range of the workability evaluation value required for the concrete to be placed, the above concrete crushing having a predetermined particle size distribution is obtained by rolling the existing concrete structure according to the set operating conditions. A thing is obtained and the said ready-mixed concrete which uses this as an aggregate is manufactured.

  On the other hand, if the measured evaluation value of the ready-mixed concrete is outside the range of the evaluated value of the workability required for the concrete to be placed, the operating condition of the crusher A is changed. That is, if it is determined that the large particle size distribution is exceeded in the particle size distribution of the crushed material crushed by the crusher A, whether or not the moving distance (crushing pitch) of the crushing blade 1 can be shortened is determined. Judging and shortening if possible, increase the number of crushing blades 1 if not possible. In addition, when the crushed material exceeds the small diameter as aggregate, it is possible to judge whether it is possible to increase the moving distance (crushing pitch) of the crushing blade 1 contrary to the above. If it is not possible, the number of crushing blades 1 is reduced.

  After changing the operating conditions in this way, the existing concrete structure was again smashed by the crusher A, and the aggregate was put into the mixer together with water and cement using the total amount of the crushed material obtained as an aggregate. After preparing ready-mixed concrete by kneading, the evaluation value of the workability of this ready-mixed concrete is measured. Then, this workability evaluation value is compared with the workability evaluation value required for the concrete to be placed, and the measured workability evaluation value of the ready-mixed concrete is the workability required for the concrete to be placed. If the existing concrete structure is beaten under the changed operating conditions, the concrete crushed material having a predetermined particle size distribution is obtained, and the ready-mixed concrete using the aggregate is used as an aggregate. To manufacture. If the measured value of the ready-mixed concrete workability is outside the range of the workability evaluation value required for the concrete to be placed, the operating conditions of the crusher A are changed in the same manner as described above, It is adjusted so that ready-mixed concrete having workability characteristics can be manufactured.

The simplified front view of the lower part of the crusher which has attached the crushing blade. The simplified front view which shows the procedure which crushes concrete. The relationship diagram of the number of crushing blades and the size of the crushed material. The relationship figure of the installation interval of a crushing blade, and the dimension of a crushing thing. Explanatory drawing at the time of changing the movement distance of a crushing blade into large and small. The flowchart which shows the manufacturing method of ready-mixed concrete. The flowchart which shows another manufacturing method of ready-mixed concrete.

Explanation of symbols

A Crusher C Existing concrete 1 Crushing blade

Claims (4)

  A method for producing ready-mixed concrete using a crushed material obtained by crushing an existing concrete structure by striking a crusher having a plurality of crushing blades as an aggregate, the crusher under a certain operating condition The workability evaluation value of ready-mixed concrete is detected by mixing the crushed material of the existing concrete structure that has been crushed by the operation of the concrete with water and cement at a predetermined blending ratio. The evaluation value of workability and the evaluation value of workability required for concrete to be placed are compared. Based on this comparison, the workability evaluation value of the above-mentioned ready-mixed concrete is required for concrete to be placed. A method for producing ready-mixed concrete, characterized in that the operating conditions of the crusher are adjusted so that the evaluation value is as follows.   The operating conditions of the crusher are determined by the striking force per crushing blade, the crushing blade mounting interval, or the movement distance of the crushing blade to the next crushing position, and at least one of these conditions is changed. 2. The method for producing ready-mixed concrete according to claim 1, wherein the operating conditions are adjusted so that the aggregate particle size distribution required for ready-mixed concrete to be placed is obtained.   The change in the impact force per crushing blade of the crusher and the crushing blade mounting interval is performed by changing the number of crushing blades installed within a fixed mounting area. The manufacturing method of the aggregate for ready-mixed concrete as described. The evaluation value of workability is one of a slump value of ready-mixed concrete, a slump flow value, a rotational resistance value of a mixer for kneading crushed material, water and cement, or a surface change of the kneaded material. The method for producing ready-mixed concrete according to claim 1.

Images