JP4041859B2 - Water-permeable / water-retaining ceramic block and manufacturing method thereof - Google Patents

Description

  The present invention relates to a technology for providing a light weight ceramic block that has both high water permeability and water retention and is excellent in freeze-thaw resistance and can be laid on the rooftop of an existing building with resource saving and energy saving.

  Ceramic blocks having water permeability and water retention are used for pavement materials for pedestrian roads and plazas for the purpose of mitigating urban heat island phenomena and measures for recycling waste.

  However, the environment in urban areas is getting worse year by year, and as a measure to further improve the urban environment, in recent years, greening has been promoted on the rooftops and walls of buildings, and can be laid on the rooftops of existing buildings. Although there is a demand for water-retaining pavement materials, there are only water-permeable pavement materials that have hardened rubber chips due to the problem of load resistance of buildings, and there are no lightweight and highly functional pavement materials.

From the viewpoint of relatively light weight and high strength compared to cement-based pavement materials and effective use of resources, conventional water permeable materials such as waste glass, ceramic waste, and sewage sludge molten slag A ceramic block has been developed, and the following prior art is known for its production method.
In Japanese Patent Laid-Open No. 9-30873, water permeability and water retention are excellent in a manufacturing method in which a mixture containing an aggregate containing 75% by weight or more of steel slag adjusted to a maximum particle size of 9.5 mm or less and a sintered binder is fired after molding. Get a ceramic block. In JP-A-9-194269, a mixture of an aggregate composed mainly of igneous rock and a binder having a lower melting point is molded and fired, or a ceramic pulverized product and a low melting point binder are laminated on the upper layer for firing. A method for producing a ceramic block having water permeability, characterized by comprising: In JP-A-9-194268, a method of drying and firing after pressure molding using aggregate, inorganic binder, pregelatinized starch and the like. In JP-A-10-17376, a chemical composition range for controlling the melting for obtaining a water-permeable ceramic excellent in bending strength and water permeability. In JP-A-11-268972, a method of firing at 1000 to 1250 ° C. after kneading and pressure forming using electric furnace oxidation slag as a raw material. Japanese Patent Laid-Open No. 2000-203959 is characterized in that a mixture containing 75% by weight or more of sewage sludge molten slag containing oxide crystals such as calcium, silicon, aluminum and the like is aggregated at 800 to 1200 ° C. A method for producing a ceramic block having water permeability and water retention and excellent strength JP-A-2001-39780 is a method in which a sintered binder is mixed with an aggregate made of sewage sludge molten slag and ceramic waste, and then sintered at 800 to 1200 ° C. In Japanese Patent Laid-Open No. 2001-342055, water is added to a porcelain aggregate having an average particle diameter in the range of 1 to 3 mm, the surface is mixed with water, a non-plastic binder is added, and then a plastic binder is added. And forming a molded body having a porosity of 20% or more, and then firing within a range of 850 to 1300 ° C.

  Etc., both are 1. 1. Use waste as an aggregate material. 2. Cover the aggregate around the binder to be fused to be vitrified by firing. It is described as being characterized by high strength while being highly water permeable and water retentive.

  The disadvantages common to them are: 1. Since the binder around the aggregate is glassy and amorphous, cracks are likely to propagate due to thermal shock and mechanical shock. If the unevenness of the surface is not made quite large, there is a drawback that it is easy to slip when it gets wet, especially when it gets wet. 3. Freezing damage does not occur in the case of water permeability only, but if there is a void that also has water retention capacity, resistance to freezing and thawing will be low, and it cannot be used in cold snowy areas. For example, it is impossible to lay on the roof of an existing building due to heavy product weight.

As an effective technology to solve such a problem, the applicants of the present application acquired,
There exists patent 3094226 (crystallized glass composite ceramics and its manufacturing method). This is because calcium silicate hydrate in cement waste blended as a raw material for fusion binder undergoes phase transition by firing, and β-wollastonite (CaO · SiO 2) needles in the vitreous surrounding the aggregate The above-mentioned disadvantages 1 are obtained by generating crystals and utilizing the difference in thermal characteristics between the aggregate particles and the grain boundary part. And 2. Can be solved.

However, in order to ensure water permeability, an aggregate raw material having a single particle size distribution that increases the pore size and a small amount of sintering binder that ensures a high porosity are used immediately after molding. It is a common problem of the prior art that the green body has a low strength and lacks handling properties.
JP-A-9-71485 is a method for producing porous ceramics, in which a silicate sol such as water glass is added as a molding binder in order to increase the shape retention of the molded body, which is a problem, and this is gelled. is suggesting.

  There is a limit in the conventional method due to the correlation that lowering the density reduces strength while holding water permeability, water retention, strength, etc. at a high level, and if water retention is increased, frost resistance The problem of the decline in performance was not solved.

  In addition, when roofing an existing building, the allowable weight is about 80 kg per square meter, and even if you want to use water-permeable and water-retaining pavement materials in addition to greening parts such as rooftop squares and walkways, the conventional inorganic The paving material could not be used.

  Further, in the prior art, except for the method of Patent Document 10, the manufacturing method is not until after adding a large amount of an organic binder and press-molding using a mold to completely dry and cure the molded body. Many resources, time, and energy were consumed for manufacture, such as being unable to convey and the products on the market being baked at a high temperature of 900 to 1100 ° C.

  In order to solve these problems, the present invention differs from a conventional water-permeable / water-retaining ceramic block, as shown in FIG. A water-permeable crystallized glass composite ceramic that has high strength and is not slippery due to the effect of the formation of acicular or columnar β-wollastonite or devitrite (Na2O · 3CaO · 6SiO2) crystals in the boundary) To do. Further, the lower base layer has a structure made of foamed glass having high water retention and having continuous pores having a large pore diameter in order to enhance frost damage resistance.

  Unlike the two-layer structure used in the prior art, the upper surface layer is not merely for the purpose of design, anti-slip, clogging prevention, etc., but the strength and water permeability function, and the lower base layer mainly has a water retention function. It is a structure that aims to meet the product specifications and performance required by changing the thickness of each layer and to control the material properties.

  As the main raw material of the upper surface layer portion that is required to have high strength while having water permeability, an aggregate having a diameter of 4.8 to 2.4 mm obtained by crushing and sieving waste glass is used as the main raw material, A raw material containing calcium silicate hydrate is used for crystal formation at a low temperature.

  Unlike the structure in which fine particles having a large porosity are fused and sintered only by vitreous matter, the lower base layer portion having water retention has a continuous large pore diameter, such as limestone and Finely crushed glass mixed with carbonate mineral such as dolomite as a foaming agent is used as a raw material.

  In addition, in order to form and fire the crystallized glass composite ceramic and the foamed glass integrally to strongly fuse the upper and lower layers, the firing temperature is a firing temperature range of 750 ° C. to 900 ° C., and the firing atmosphere in the furnace is Use an oxidizing atmosphere.

  Furthermore, since the raw material aggregate is coarse, the strength of the molded product is low, so unlike conventional press molding using a metal mold, the material is spread on a setter that is resistant to firing. Then, a method is adopted in which the compaction is performed by the rolling pressure of a roller, and the material can be directly conveyed to a firing furnace.

  By using soda-lime-based waste glass as the main raw material of the aggregate material used for the upper surface layer, fusion with a sintered binder and crystal formation reaction proceed at a low temperature, and the diameter of 4.8 to 2.4 mm Large continuous pores can be obtained by setting the amount of aggregate to 90 to 70%.

  In addition, the calcium silicate hydrate in the sintered binder raw material undergoes phase transition to β-wollastonite at 750 ° C., promotes the formation of devitrite on the aggregate glass surface, and contains acicular crystals at the grain boundaries. High strength can be obtained by forming a layer and generating compressive stress.

  By using carbonate minerals such as limestone and dolomite as a foaming agent in the lower base layer raw material, it becomes possible to generate carbon dioxide in a wide temperature range of 750 to 900 ° C. It can be reduced, and the resulting pores have many continuous pores, a large diameter and a structure with excellent frost resistance.

  The upper surface layer is usually formed by applying vibration to such an extent that the aggregate particles and the sintered binder do not separate, filling and pressing, or rolling with a roller to make the structure uniform and fired. High water permeability is secured.

  Next, when the foam glass raw material that becomes the lower base layer is filled on the upper surface raw material that has been pressure-molded after filling as shown in FIG. 2, this is filled evenly in the aggregate gap at the boundary because the particle size is fine. The

  When the molded body thus obtained is fired, the soda-lime glass aggregate and the foamed glass raw material are suddenly softened and sintered from around 600 ° C., and at 750 ° C. at the grain boundary of the calcium silicate. While crystallization of β-wollastonite and generation of devitrite are initiated by the phase transition, the surface layer portion is sintered to form a water permeable layer (crystallized glass composite ceramics). At the same time, foamed glass constituting the base layer is formed by decomposition of the carbonate mineral, and the surface layer and the base layer are integrated.

  When the firing temperature exceeds 900 ° C., the foamed glass layer is not formed due to shrinkage and densification due to the decrease in the viscosity of the foamed glass and the decrease in the supply amount of the decomposition gas.

  Usually, when the diameter of the continuous pores present in the sintered body is large, it is known that the expansion pressure due to freezing of water is easily released, so that it is difficult to break. Both the base part and the base layer part have large pore diameters, the aggregate fused part of the surface layer part with water permeability function is high strength, the foam glass of the base layer part with water retention function is lightweight, so it has both water permeability and water retention It becomes a lightweight ceramic block with excellent strength and freeze-thaw resistance.

  In order to produce a ceramic block by low-temperature firing, the aggregate material constituting the upper surface layer having a water permeability function is soda-lime glass-based glass waste material, and the binder for fusing it is obtained as a medium melting material. Fine powder glass generated at the time, silica stone or waste foundry sand as the silicate raw material, waste material generated during the production of cement concrete secondary product or recycled aggregate, or recovered calcium silicate product, etc., are used as the crystal forming raw material.

  In addition, it is desirable that the foamed glass raw material constituting the base layer part is pulverized and mixed to a fine powder glass containing 2 to 6% by weight of a mixture of limestone and dolomite as a foaming material to an average particle size of 74 microns or less.

  The blending ratio of the aggregate constituting the surface layer and the binder to be fused is optimally 90 to 70% by weight in terms of strength and water permeability.

  The molding method is as follows. First, a binder for molding is added to the raw material for the surface layer, and a granulated material is added with a binder for fusion. The raw material of foam glass is added and further filling and pressure molding are performed.

  The ratio of the surface layer raw material to the base layer raw material is set in consideration of the thickness necessary for the surface layer to satisfy the required strength, and the base layer to the required product thickness and bulk density. In the case of a 30 cm square plate with a thickness of 6 cm, the surface layer is usually about 4 to 3 cm in the base layer of 2 to 3 cm.

  In addition, since the degree of foaming of the base layer affects the bulk density, water absorption rate, strength, etc., in order to control this with the raw material blending ratio, inorganic powder with higher fire resistance than soda lime glass is adjusted like clay It is desirable to use it as a material. .

  Firing is performed at a maximum temperature of 850 ° C., and the atmosphere in the furnace is oxidized. When an organic binder is used, the temperature is raised so that the substrate is not reduced, and cooling is gradually performed so that the substrate is cooled and does not crack.

  In addition, since the foamed glass of the base layer is expanded and deformed after firing, it is desirable to perform cutting and polishing so that the shape satisfies the product dimensions.

  As a vitreous raw material for aggregate glass, sintered binder, and foamed glass, a soda-lime glass plate glass waste (hereinafter referred to as waste glass) is pulverized through a 4.8 mm sieve and 4.8 mm to 2 The particles of 4 mm were aggregate glass, and the particles of 1.2 mm or less were used as waste glass fine powder for a sintered binder material.

  Waste glass fine powder-silica fine powder-cement waste (autoclaved hardened body of waste cement slurry discarded from concrete pile factory) system was fired and the sintering degree was the best in the firing temperature range of 750-900 ° C. Yes, 40% by weight of waste glass fine powder, 60% by weight (mixture of 66% by weight of waste glass fine powder, 16% by weight of quartzite fine powder, 18% by weight of cement waste) containing a lot of crystals such as devitrite and β-wollastonite % (Hereinafter referred to as composite glass raw material) was used as a sintered binder.

As a water-permeable tile raw material constituting the surface layer part,
Aggregate glass: 80% by weight
Composite glass raw material 20% by weight
Were mixed to obtain a granulated product.

As a foam glass raw material constituting the base layer part,
Waste glass fine powder: 92% by weight
Limestone fine powder: 3% by weight
Dolomite ... 1% by weight
Bentonite: 4% by weight
Were mixed, pulverized and granulated.

  The water-permeable tile raw material granulated material of the surface layer portion is filled into a 300 mm square formwork in a certain thickness (amount to be about 20 mm thick after firing), press-molded, and then the foam glass of the base layer portion thereon The raw material granule was filled (amount of foamed portion having a thickness of 40 mm or more after firing) and pressed again to obtain a molded body.

  After the molded body was fired at 850 to 900 ° C. in an oxidizing atmosphere, a flat plate was manufactured by cutting so that the total thickness was 60 mm.

  Table 1 shows the results of comparing the physical properties of the flat plate of Example 1 such as bending strength, bulk density, water permeability (coefficient), and water absorption (water retention) with cement-based water permeable block commercial products.

  As a result of 10 cycles of frost damage resistance performance based on the JIS A5204 ceramic tile regulations (in the air frozen water melting method at -20 ° C to +20), 5 commercially available water-permeable / water-retaining ceramic blocks were tested. Although all were damaged, the water-permeable / water-retaining flat plate and the cement-based horizontal horizontal plate of Example 1 were not abnormal.

  As a result of comparing the sliding resistance as a paving material by the BPN method, the flat plate of Example 1 shows 75 equivalent to cement products, which is a high value compared with 30-60 of commercially available water-permeable / water-retaining ceramic blocks, and is usually safe. The value of 40, which is said to be, was greatly exceeded.

  As a result of observing the surface of the surface layer part and the grain boundary part with an electron microscope, needle-like or columnar crystals having a length of several tens of microns were observed. When the crystals were identified by X-ray diffraction analysis, the crystals were identified as devitrite and β -Wollastonite.

  Using the apparatus shown in FIG. 2, the raw material granule for the surface layer used in Example 1 was laid on a fireproof shelf board, consolidated to a thickness of 3 cm with a roller, and then placed on the upper part of the plate-shaped surface layer part. Then, the foamed glass raw material for the base layer part used in Example 1 was spread and molded, and then fired at 850 to 900 ° C. to obtain a ceramic block having the same physical properties as in Example 1.

In order to confirm the performance of the water-permeable / water-retaining ceramic of Example 1 as a pavement material to alleviate the urban heat island phenomenon, in an artificial weather room, the room temperature is 33 ° C. and the wind speed is 2.3 m / sec. As a result of measuring the effect, the evaporation efficiency of the saturated sample was 0.8, and the latent heat effect was maintained for 30 hours.

  The water-permeable / water-retaining ceramic of the present invention has a feature that is lightweight and has extremely high water-retaining performance compared to commercially available water-permeable / water-retaining pavement materials, while ensuring sufficient strength as a paving material, Of course, as a paving material for rooftops, verandas, and passages of existing buildings, it is optimal as a paving material that can contribute to the improvement of the urban environment in addition to the advantages of structural design of buildings.

It is a schematic diagram of the cross-sectional structure of the water-permeable / water-retaining exothermic ceramic block of the present invention. 6 is a schematic diagram of a molding apparatus used in Example 3. FIG.

Explanation of symbols

1 Surface layer composed of crystallized glass composite ceramics with soda-lime waste glass aggregate fused with a sintered binder and having a water-permeable function with a structure including β-wollastonite and devitrite crystals in the grain boundary glassy material .
2 A base layer of foam glass having a water retention function by continuous pores.
3 Aggregate grain boundary (fused) part and surface part made of glassy material containing crystals such as β-wollastonite and devitrite.
4 Waste glass aggregate with a particle size of 4.8-2.4 mm 5 Conveyor belt 6 Refractory material (setter)
7 Hopper 8 Raw material granules for surface layer 9 Rolling roller
10 Raw material composition for base layer (foamed glass raw material)
11 Raw material of base layer formed by spreading to a certain thickness
12 Rolled surface layer raw material

Claims (2)

An upper surface layer having continuous pores in which aggregates are fused with a glassy material containing β-wollastonite and devitrite crystals and a lower base layer made of foamed glass having continuous pores , and the upper surface layer and the lower base layer are obtained by firing. A ceramic block with both water permeability and water retention, characterized by an integral structure . To 90-70% by weight of aggregate having a particle diameter of 5 to 2.5 mm composed of at least one selected from the group consisting of soda-lime waste glass, ceramic waste, municipal waste melting slag, sewage sludge melting slag, A raw material granule for the surface layer obtained by adding 10 to 30% by weight of a composition that produces a vitreous material containing β-wollastonite crystals and devitrite crystals by firing as a sintered binder is made of a refractory material. A process of spreading or filling a setter on a set thickness, a process of forming it by compaction or pressure press by roller rolling, and a foam glass raw material that generates continuous pores as a base layer raw material on the top The step of leveling and filling, then the step of compacting by roller rolling or forming with a pressure press, and the step of firing at a temperature of 750 to 900 ° C. in an oxidizing atmosphere. A method for producing a ceramic block having both water permeability and water retention, which is performed next and having the structure according to claim 1.

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