JP2011168470A - Waste gypsum regenerated concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To recycle waste gypsum of environmental pollution waste as concrete aggregate by adding 1-2% binder into a pulverized material of the harmful waste gypsum to give strength as same as that of the conventional sand-cement based concrete, to make the amount of eluted fluorine harmless, to be made lightweight from 2.3 to 1.8 in the specific gravity to recycle the waste gypsum material as a building material and to make the waste gypsum pollution-free. <P>SOLUTION: The waste gypsum is used as the cement aggregate by surface-treating the waste gypsum which is porous and from which fluorine is eluted with PVAC. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to detoxification treatment of waste gypsum and its reuse.

The present invention has developed a material that can be reused harmlessly by treating waste gypsum, an environmental pollutant that has no use.

The present invention eliminates pollution of environmental pollutants such as fluorine compounds eluted from waste gypsum and prevents strength reduction compared to conventional rock grinding materials such as sand in order to reuse them as concrete additives. On offer.

The present invention is an organic material that enables an elution-preventing reinforcement effect in which the amount of fluorine dissolved in a cement mortar material containing at least 50% waste gypsum is 0.8 ppm or less and the compressive strength is 20 MPa or more equivalent to that of general rock aggregate cement mortar. It is in the development of system binding materials.

The additive obtained by the present invention makes it possible to make waste gypsum pollution-free and to reuse building blocks, paving stones and the like.

By adding waste gypsum to 100-1000 microns in a solid content of 0.5 to 5%, the amount of waste gypsum as an environmental pollutant can be reduced to 50% without deteriorating cement strength. Invented a binding material, a blending condition thereof, and a production method capable of enabling a fluorine to be 0.8 ppm or less of the environmental standard and a compressive strength of 20 MPa or more even when used in an amount of at least%.

The invented binding material is optimally one having a PVAC (vinyl acetate) -based reactive group, which is strong in alkali, such as acrylic resin and epoxy resin, and has a reactive group that is hydrophilic and shared with cement hydration reaction. Things apply. In particular, waste gypsum is a porous material and requires a bundling effect to improve strength. Therefore, the binding material has an elongation of at least 20%, is hardly hydrolyzed by cement alkali, and is waterproof and cement-free. A PVAC material that retains the water retaining effect and is inexpensive is suitable.

The optimum conditions for carrying out the invention are: 55% waste gypsum by weight ratio, 24% cement, 20% sand, 1% binding material and good compression molding conditions with a compression pressure of 20 MPa. The compression strength at this time is about 20 MPa or more and the specific gravity. Was 1.8. This is equivalent or stronger in strength than conventional concrete mortar with 75% cement, 25% specific gravity and 2.3% specific gravity. In addition, the material mixing water in optimal implementation conditions was 23% by solid content weight ratio. As for the blending procedure of the material, the method of mixing the waste gypsum and the water-soluble binder, mixing the sand, and finally mixing the cement is the strongest. Moreover, the elution fluorine of a solid substance was 0.8 ppm or less equivalent to concrete mortar.

The most economically strong and effective addition amount of the binding material was 2% by weight. The most effective material for the binding material was a 6: 4 blend of PVAC and EVA. In this case, the strength increases from 1% to 2.5% in direct proportion to the amount added. On the other hand, the acrylic type has a lower effect of about 20% than the PVAC and EVA types. Epoxy systems are more effective than PVAC systems, but are more expensive and are inferior to PVAC systems in terms of economic effects.

The amount of water added and the molding pressure affect the strength. The optimum amount of water added was 11% when sand cement concrete was formed, but 20-25% water addition was the most stable and stable when waste binder was added to 2% binder. Further, the molding pressure is the same at 2 MPa or more, but the strength is reduced proportionally below. In practice, a minimum of 0.5 MPa is necessary.

As a result of further testing the reinforcing effect in the above examples, the addition of glass fiber was effective. The effect appears prominently when the addition amount is 3% or more, and generally follows the composite rule in proportion to the addition rule, and when 7 mm cut fiber is used, there is an addition effect. It was possible to add up to about 25%. Suitable glass fiber is C glass of alkali glass fiber.

As a result of conducting tests to improve the production rate, the effect of the cement rapid hardener was strong, and several tens of minutes could be removed even at room temperature. However, it was not completely cured, but the shape was stable. The time was reduced proportionally with increasing temperature. For this reason, the production equipment has a heating mechanism, and a rapid curing agent is suitable for production.

Claims (2)

1% of aqueous solution of resin compound such as vinyl acetate resin, acrylic resin, epoxy resin, etc. on inorganic material with more than 50% of waste gypsum by removing paper members from gypsum board and 15% of cement The above is a particle-dispersed composite structure in which a pigment, a cement rapid curing agent and, if necessary, an inorganic sand are filled and diffused and mixed, and then pressure-solidified and molded. The method for producing a particle-dispersed composite structure according to claim 1, wherein 1% or more of an aqueous solution of a resin compound such as vinyl acetate resin, acrylic resin, or epoxy resin is first mixed with waste gypsum, and then cement or sand emphasis material is added and mixed. Mixing the required moisture of 25% or less to make a molding raw material, putting the required amount into the mold in a bulk state, and the mold clamping pressure is at least 0.5 MPa or more, and if necessary, heating up to 150 ° C. or less The product is produced by demolding from the mold in an uncured state or a completely cured state where the shape can be maintained.