JP2000000483A - Method for pulverizing concrete lump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate coarse aggregate without damage, to execute regenerating treatment of a cement paste component and to efficiently obtain regenerated cement by heating concrete lumps to evaporate the moisture contained therein, then absorbing the water and subjecting the concrete lumps to freezing, thawing and pulverizing. SOLUTION: Concrete lumps generated in disassembly, etc., of buildings are dried by a heating and drying machine A to generate the fine crazes and cracks in the mortar paste portions and simultaneously to evaporate the moisture contained therein, by which the concrete lumps are dried to an absolute dry state. Next, the concrete lumps are fed into a submersion device B storing the water and are subjected to immersion in the water, by which the concrete lumps are rapidly cooled from high temp. to expand the very small crazes and cracks and the water is sufficiently penetrated and absorbed into the internal crazes and cracks to a saturation state. The moisture thereof is frozen and expanded to additionally expand the crazes and cracks in a freezing device C and thereafter, the concrete lumps are heated and thawed in a thawing device D, by which the tissues are embrittled. The concrete lumps are pulverized in a separating and pulverizing device E and thereafter, in a classifying treatment machine F, the concrete lumps are classified to the coarse aggregate, fine aggregate and cement powder which are recycled. The present aggregate rate in the regenerated aggregate is improved and the percentage of water absorption is lowered. The quality of the concrete using the regenerated aggregate is thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for regenerating concrete fragments generated from demolishing an existing building.

[0002]

2. Description of the Related Art Conventionally, a concrete block obtained by dismantling an existing building is regenerated by a crusher as shown in FIG. 3, for example, so that it can be reused as roadbed material or recycled aggregate. ing.

[0003] In the above recycling method, a concrete mass is subjected to a tertiary treatment by a crusher (impeller breaker), and is divided into fine aggregate, coarse aggregate and other fine powder to produce recycled aggregate.

[0004]

However, in the above-mentioned regenerating method, if the number of times of pulverization is increased in order to produce a coarse aggregate with little mortar adhesion, the amount of fine aggregate increases, and if the pulverization method is used. Since the coarse aggregate of the ore is crushed, only about 20% of the entire concrete block can be actually used as the recycled coarse aggregate. Further, when the recycled aggregate is analyzed, as shown in FIG. 4, a large amount of mortar adheres around the aggregate. Due to the adhered mortar, the water absorption of the conventional recycled aggregate is 5% to 13% as shown in FIG.
This is a very large value as compared with the water absorption of ordinary aggregate of about 1.5%.

[0005] As described above, the recycled aggregate contains coarse aggregate of mortar and coarse aggregate to which mortar is attached.
High water absorption. When concrete is made using such a recycled aggregate having a large water absorption, the water / cement ratio changes and the quality varies greatly, and if the mortar of the recycled aggregate contains salt, the durability is poor. Therefore, it cannot be used as a superstructure material for building structures.

As described above, it is impossible to separate the concrete mass from the mortar component without damaging the coarse aggregate of the raw stone by the conventional method for regenerating the concrete mass.
It is technically impossible to divide the mortar into fine aggregate of raw stone and cement paste, and there is a problem to be solved. In addition, since the recycled fine aggregate cannot be divided into the fine aggregate of the raw stone and the cement paste, it is inefficient to regenerate the cement paste and make the recycled cement, and there is a problem to be solved. .

[0007]

The gist of the present invention for solving the above-mentioned problems of the method for pulverizing a concrete lump according to the present invention is to heat the concrete lump by a heating means to evaporate the water contained therein, and to obtain the heat-treated concrete. Let the mass absorb water,
Thereafter, the concrete mass is frozen and further thawed, and the thawed concrete mass is pulverized by a pulverizer.

The heating temperature of the heating means is in the range of about 200 ° C. to 400 ° C .; Immersing the concrete mass in a immersion device to make the water content saturated; the freezing temperature when freezing the concrete mass is about −15 ° C.
It is included that it is in the range of -50C.

According to the method for pulverizing a concrete lump according to the present invention, before the freezing and thawing, the concrete lump is preliminarily subjected to a heat treatment so that the moisture contained in the lump is converted into water vapor and then diffused. Water is sufficiently absorbed by tiny cracks and bubbles to make it saturated.

[0010] By freezing and thawing the saturated concrete block, the water that has entered into the minute gaps of the concrete block expands in volume, and the cracks in the concrete block progress and pulverize. It will be easier. Fine cracks occur at the interface between the coarse aggregate and the mortar portion, or at the interface between the fine aggregate of the mortar portion and the fine particle portion such as cement, resulting in the formation of coarse aggregate, fine aggregate and fine cement particles. It is easy to classify.

By setting the heating temperature in the range of about 200 ° C. to 400 ° C., it is possible to evaporate the water content and to make the concrete in a completely dry state without adversely affecting the coarse aggregate of the concrete mass. Fine cracks occur in the mortar portion of the lumps, and the concrete lumps are weakened. And, in the heating temperature range,
The optimal heating temperature for increasing the regeneration capacity of the concrete block is 300 ° C.

Also, by absorbing water to the saturated state after the heat treatment of the concrete mass, micro cracks due to quenching are enlarged, and volume expansion and destruction due to freezing of the contained water become more efficient. The concrete mass is weakened.

[0013] By setting the freezing temperature at the time of freezing the concrete mass in the range of about -15 ° C to -50 ° C, the volume expansion of water increases.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method for pulverizing a concrete block according to the present invention will be described with reference to the drawings. The flow of the crushing method according to the present invention will be described with reference to the flow of the work procedure shown in FIG. 1 and FIG. 2. First, in flow 1, a concrete block generated by dismantling an existing building is used as a heating means. It is dried by the heating dryer A.

In the heating dryer A, the concrete mass is heated to about 200 ° C. to 400 ° C. The optimal temperature that does not adversely affect the coarse aggregate is 300 ° C. At about 200 ° C., the concrete mass starts to lose capillary water inside the concrete and dewater gel water from the cement hydrate.

When the temperature further rises, as shown in FIG.
Due to the difference in the coefficient of thermal expansion between the aggregate and the mortar matrix, thermal stress is generated near the interface between the two, causing minute cracks inside the concrete. The minute cracks are generated at the air bubbles and voids in the mortar or at the interface between the mortar and the coarse aggregate.

However, if the heating temperature is about 500 ° C. or higher, some aggregates are affected by high temperatures, so the maximum temperature is set to 400 ° C. The concrete mass can reduce the compressive strength and the tensile strength of the concrete to 40% to 70% as compared with the strength before the treatment by the high temperature treatment.

The heat used for this purpose may be, for example, the heat of a waste treatment plant. Then, in the mortar paste portion or the like of the concrete block, fine cracks are generated by heat, and the moisture contained in the block is evaporated to be dried to an absolutely dry state.

Next, in flow 2, the absolutely dry and hot concrete mass discharged from the heating and drying machine A is put into a water immersion device B such as a storage tank for storing water, and is immersed therein.

Since the concrete mass is rapidly cooled from a high temperature, minute cracks are further enlarged. As a result, it penetrates into the cracks inside the heat-treated concrete mass, absorbs water sufficiently, and makes it saturated.

Next, in a flow 3, the concrete mass is frozen by the freezing device C. Freezing is performed by rapid cooling to increase the volume expansion of the water. As this freezing device,
For example, the refrigerant is frozen in a nitrogen gas or natural environment.

When the moisture in the concrete mass starts to freeze, ice crystals are generated, and the volume of the ice crystals gradually expands.
As shown in the figure, the maximum volume expansion occurs at about −40 ° C.
At a later temperature, volume shrinkage starts.

[0023] By this freezing action, saturated water that has penetrated into the interior of the concrete block freezes and expands in volume,
Cracks are further enlarged. Fine cracks are generated at the interface between the coarse aggregate and the mortar portion, and at the interface between the fine aggregate and the fine particle portion such as cement in the mortar portion.

Next, in a flow 4, the frozen concrete mass is thawed by heating by the thawing device D (for example, heat of a waste disposal site) or by a natural environment inside and outside a factory or the like. When the concrete mass begins to thaw, a maximum volume expansion larger than the maximum volume at the time of freezing occurs at around -35 ° C, and then the volume shrinks until the thawing is completed. Is destroyed, so that the volume ratio does not return to the original state.

As a result, the structure of the concrete block is significantly weakened. Then, in a flow 5, the concrete mass is put into the separation and crushing device E and crushed.

Thereafter, in a flow 6, the concrete lump is separated into coarse aggregate, fine aggregate and cement powder by a sorting machine F and reused.

According to the method of the present invention, the mortar component is almost completely separated from the regenerated coarse aggregate, the mortar component is separated into the fine aggregate and the cement component, the water absorption of the regenerated aggregate is reduced, and the regenerated bone is reduced. The present aggregate ratio in the aggregate is improved, and the quality of the concrete using the recycled aggregate is uniformly improved.

[0028]

As described above, the concrete lump pulverization method according to the present invention is characterized in that the concrete lump is heated by the heating means to evaporate the water content, and the heat-treated concrete lump absorbs water. After that, the concrete mass is frozen and further thawed, and the thawed concrete mass is pulverized by a pulverizer. Therefore, before the concrete mass is frozen / thawed, the concrete mass is subjected to a heat treatment to further absorb moisture. Cracking during thawing is promoted more than before, and the mortar component is sufficiently separated from the coarse aggregate, and the mortar component is further separated into cement and fine aggregate. As a result, the water absorption of the recycled aggregate is reduced and it can be used as recycled aggregate, the current aggregate ratio of recycled aggregate is improved, and the quality of concrete using this recycled aggregate is also improved by uniformity It has an excellent effect of doing so. In addition, the cement component has an excellent effect that it can be effectively used as a raw material for recycled cement.

By setting the heating temperature in the range of about 200 ° C. to 400 ° C., it is possible to evaporate the water content and to make the concrete in a completely dry state without adversely affecting the coarse aggregate of the concrete mass. A minute crack is generated in the mortar portion of the lump, which not only weakens the concrete lump, but also has an excellent effect that, when the heating temperature is set to about 300 ° C., the regeneration treatment capacity of the concrete lump is most enhanced. Things.

Further, by absorbing water to the saturated state after the heat treatment of the concrete block, micro cracks due to rapid cooling are enlarged, and volume expansion and destruction due to freezing of the contained water become more efficient. This has an excellent effect that the embrittlement of the concrete mass is promoted.

By setting the freezing temperature at the time of freezing the concrete mass in the range of about −15 ° C. to −50 ° C., an excellent effect of increasing the volume expansion of water is obtained.

Even if the concrete block contains a metal such as a reinforcing bar, it is not mechanically crushed, so that the teeth of the crusher are not damaged.

[Brief description of the drawings]

FIG. 1 is a view of an operation procedure showing a method for crushing a concrete lump according to the present invention.

FIG. 2 is a view of a process showing a method for crushing a concrete lump according to the present invention.

FIG. 3 is an explanatory diagram showing strain characteristics due to thermal expansion of aggregate and concrete at a high temperature.

FIG. 4 is an explanatory diagram showing characteristics of expansion and contraction caused by freezing and thawing of a concrete block.

FIG. 5 is an explanatory view showing a method of pulverizing a concrete lump according to a conventional example.

FIG. 6 is an explanatory view showing an enlarged state of aggregate separated by a pulverizing method according to the conventional example.

FIG. 7 is a view showing a water absorption rate of a regenerated fine aggregate pulverized by the conventional example.

[Explanation of symbols]

1 A flow showing a heating process, a flow showing a immersion process, a flow showing a freezing process, a flow showing a thawing process, a flow showing a separation process, and a flow showing a separation process.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiro Itaya 1-7-1 Kyobashi, Chuo-ku, Tokyo Toda Construction Co., Ltd. (72) Inventor Munehiro Umemoto 1-7-1 Kyobashi, Chuo-ku, Tokyo Toda Construction Co., Ltd. F term in the formula company (reference) 4D067 CG06 CG09 EE32 EE34 EE50 GA06

Claims (4)

[Claims] 1. The concrete mass is heated by a heating means to evaporate the water content, the water is absorbed by the heat-treated concrete mass, and then the concrete mass is frozen and further thawed. Pulverizing the lump with a pulverizer; a method for pulverizing a concrete lump. 2. The heating temperature of the heating means is about 200 ° C.
The method according to claim 1, wherein the temperature is in a range of 400 ° C. 3. The method according to claim 1, wherein the heat-treated concrete mass absorbs water by immersing a high-temperature concrete mass capable of evaporating contained water in a flooding device to make the contained moisture saturated. The method for crushing a concrete lump according to claim 1. 4. The method for crushing a concrete lump according to claim 1, wherein the freezing temperature at the time of freezing the concrete lump is in a range of about −15 ° C. to −50 ° C.