JP3305414B2 - How to use demolition concrete waste - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of using demolition concrete waste called "concrete glass" generated when a concrete structure is demolished.

[0002]

2. Description of the Related Art Demolition concrete waste, which is called concrete waste, is mostly disposed of as landfill waste. Recently, however, it has been recognized that it is necessary to reuse it as a construction by-product. As the method of using the seed dismantled concrete waste material, it is only used for simple spread sand or partially used for landfill, and an effective use method has not been realized. Therefore, recently, a proposal has been made to separate the dismantled concrete waste into aggregate and hardened cement, reuse the aggregate as aggregate, and dry and finely pulverize the hardened cement into recycled cement.

[0003]

However, the above-mentioned conventional method for separating and reusing aggregates has the problem that the separation of the aggregates from the hardened cement is troublesome, expensive and expensive. Recycled cement made from hardened cement contains a lot of materials that have completed the hydration reaction, and since it has passed the years, it is an inactive substance, so only low-quality, low-strength concrete can be obtained. There is a problem that there is no.

Accordingly, the present invention has been made to solve the above-mentioned problems. In order to facilitate reuse, limestone of the same series as the cement raw material is used in advance in the production of the source concrete for fine coarse aggregate. An object of the present invention is to provide a method of using demolition concrete waste material that is easy to regenerate and that can effectively prevent a decrease in strength.

[0005]

In order to solve the above-mentioned problems, according to the present invention, in order to solve the above-mentioned problems, a waste material of high-strength concrete using limestone aggregate is provided. Crushed by a crusher, and the crushed
A technical means characterized in that it is dried at about 200 ° C. to a water content of 10% or less, then pulverized by a pulverizer, sieved to a particle diameter of 105 μm or less, and used as a concrete binder or a cement substitute. It was taken.

[0006]

The use of a high performance AE water reducing agent has recently reduced the amount of water (W / C) in concrete and has made it possible to achieve workability and high strength. This type of concrete has the property that only the surface of the cement particles undergoes a hydration reaction to gel and form a film, and unhydrated remains in the center of the cement particles. Therefore, the unhydrated material whose surface is covered with the hydrated film can be rehydrated by pulverizing the powder.

However, since the above-mentioned action involves the incorporation of the completed hydration product, it causes lower quality compared to new concrete. In the present invention, it is desirable to use calcium oxide (Ca
Since limestone containing a large amount of O) and silicon dioxide (SiO ₂ ) is used as an aggregate, these limestones are mixed with cement along with the fine pulverization, and exhibit an effect of suppressing reduction in activation of cement. That is, the calcium oxide (CaO) acts as an inorganic cement activator to increase the initial strength.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings. First, in the method of the present invention, waste material of high-strength concrete using limestone aggregate is crushed by a crusher.

That is, the conventional aggregate typically uses river sand. However, river sand has been used to wash sea sand or to crush rock into sand because the river sand tends to be insufficient. Therefore, limestone is used as an aggregate when constructing a concrete structure in consideration of the convenience of reuse of the concrete waste used in the present invention. This limestone may be crushed into sand and used by mixing it with cement by a conventional method. However, a high-performance water reducing agent is added (as an example, the water content (W / C) to 50% or less.) To secure workability and strength.

[0010] When a high-strength concrete structure using the limestone aggregate becomes unnecessary, or when it becomes necessary to disassemble it after the end of its durability, this is dismantled by a conventional method to remove concrete waste material. obtain. Then, if necessary, the waste material of the concrete is crushed in advance by a crusher or the like to an appropriate size for convenience of handling in the next step.
In addition, the crushing here is when the concrete structure is dismantled by the ordinary method, there is a problem of noise and dust generation at the dismantling site,
At a minimum, it may be dismantled into a relatively large lump that does not impede transportation, for example, to a length of about 1 to 2 m. Since a large device is required, the material is crushed to a size that can be continuously transported by a normal handling device.

The crushed product is dried at about 110 to 200 ° C., crushed by a crusher and sieved to a particle diameter of 105 μm or less, and used as a concrete binder or a cement substitute.

What is dried here is that, if water is contained, the water impedes the transmission of physical force and hinders the pulverization. This is because there is a risk of doing so. In particular, limestone particles have a property of being easily hydrated, and concrete carried in as waste material is often injected with water in order to prevent dust at the time of dismantling, so that considerable amount of attached water or intrusion water also exists. Therefore, the water content is set to 10% or less at 100 to 200 ° C.

A conventionally known apparatus such as a conventionally heated tonel can be used for drying. For the purpose of efficient drying prior to drying, waste concrete may be further crushed to a certain size or less. Needless to say, in this embodiment, concrete mass having a maximum diameter of about 20 cm was put into the drying device, but the maximum diameter was several c in advance with a jaw crusher or the like.
Performing the drying step after setting m allows the thermal energy for drying to be effectively used. In addition, as described above,
It is in the pulverization stage that water impedes the transmission of physical force during pulverization, and the effect of water content can be neglected in such a coarse pulverization stage.

The dried concrete waste is pulverized by a pulverizer. It is preferable to use a plurality of pulverizers in consideration of the pulverization efficiency. In this embodiment, first, the pulverizer is coarsely pulverized by a jaw crusher (before drying). If crushed by a jaw crusher, this step may be omitted.) Then, the material is coarsely pulverized to 20 mm or less by a pulverizer called a top grinder, and further finely pulverized by a mill. Here, the pulverization is performed for the purpose of reducing the particle size as much as possible, and it goes without saying that the method of the pulverizer is not limited to the above.

The finely pulverized product is sieved with a 105 μm sieving apparatus. As the sieving apparatus, conventionally sophisticated ones can be used, and large-diameter concrete waste remaining on the sieving apparatus may be returned to the previous pulverizing step.

For comparison, when the waste material of concrete using soft sandstone as an aggregate was pulverized under the same conditions as described above, the average particle size was 25 to 27 μm, but when limestone was used as the aggregate, the average particle size was 20 to 27 μm. 23 μm and 105 μm
The ratio remaining in the sieving apparatus was about 60% when soft sandstone was used as aggregate, but about 3% when limestone was used as aggregate.
Since the limestone itself is a soft rock with a residual rate of 0 to 35%, it was confirmed that the waste material of cement can be easily miniaturized with energy saving.

The concrete obtained by using the thus obtained material as a recycled aggregate as a concrete aggregate and comparing the strength was as shown in FIG. 1. In the figure, the concrete waste materials used have the following composition. NL: Use limestone as aggregate for ordinary cement NH: Use hard sandstone as aggregate for ordinary cement BL: Use limestone as aggregate for blast furnace type B cement BH: Use hard sandstone as aggregate for blast furnace type B cement FL: Use limestone as an aggregate for Briash B cement. FH: Use hard sandstone as an aggregate for Briash B cement. HC: Add a water reducing agent to ordinary concrete and use limestone as aggregate. Also used for testing All that was done is 28 days old.

Therefore, from the test results shown in FIG. 1, it is clear that the use of limestone aggregate contributes to the improvement in strength, and limestone has a binder function.

[0019]

As described above, the present invention provides a method of using demolition concrete waste which is easy to pulverize because limestone itself is relatively soft and easy to reuse by using limestone as an aggregate. You can do it.

Further, by using limestone as an aggregate, it is possible to provide a method of using demolition concrete waste material in which the limestone exhibits a binder function by finely pulverizing the limestone, thereby effectively preventing a decrease in strength. It is.

The fine powder obtained by the present invention can also be used as a soil improving material, a filter for muddy water, and a neutralizing agent for muddy water. The present invention can provide a method of using demolition concrete waste material that can be used.

[Brief description of the drawings]

FIG. 1 is a graph showing a comparative compressive strength test result when a fine powder obtained by the present invention is mixed and used in concrete.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Mitsuko Arai 2570-4 Nishimatsu Construction, Shimotsuruma, Yamato-shi, Kanagawa Prefecture Inside the Technical Research Institute (72) Inventor Yoshihisa Nakata 2570-4 Shimotsurumama, Yamato-shi, Kanagawa Pref. (56) References JP-A-5-238790 (JP, A) JP-A-3-54137 (JP, A) JP-A-5-170498 (JP, A) (58) Fields surveyed ( Int.Cl. ⁷ , DB name) C04B 7/24 C04B 18/16

Claims (1)

(57) [Claims] 1. A high-strength concrete waste material using limestone aggregate is crushed by a crusher, and the crushed material is dried at about 110 to 200 ° C. to a water content of 10% or less, and then crushed by a crusher. A method of using demolition concrete waste material, which is sieved to a particle diameter of 105 μm or less and used as a binder material for concrete or a cement substitute.