JPS6149271B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In recent years, there has been a great deal of development in the composite of concrete or mortar with plastic. The objectives of this plastic composite include high strength, waterproofness, chemical resistance, abrasion resistance, long life, and resistance to freezing and thawing. Depending on the manufacturing method, polymer cement concrete (PCC), resin concrete (REC), etc. ), polymer-impregnated concrete (PIC), etc. The present invention relates to a method for producing polymer cement concrete that is unprecedented in weight, high strength, and inexpensive.

Traditionally, polymers are mixed into concrete,
There is a method for producing polymer cement concrete that heats the concrete after it hardens to melt the polymer and disperse it into the concrete voids. This simply attempts to close-pack the voids in the hardened concrete with polymer, but filling the fine voids with molten polymer after hardening becomes extremely difficult as the voids become smaller. Therefore, although the obtained polymer cement concrete has improved properties when compared to ordinary concrete, it has the disadvantage that it cannot provide high strength considering its weight. The inventors of the present invention have conducted extensive research to overcome these drawbacks of polymer cement concrete, and as a result, it has become possible to obtain polymer cement concrete that is lightweight, inexpensive, and relatively high in strength.

That is, by melting and dispersing the polymer and simultaneously foaming it while the cement still maintains semi-hardened fluidity, it has become possible to obtain lightweight, high-strength polymer cement concrete.
The important point here is to melt and disperse the polymer while the cement is in a semi-hardened state. By melting and dispersing the polymer while the water in the cement is hydrated with the concrete and is still in a somewhat soft state, the polymer is able to spread the cement particles and penetrate into minute voids. The dispersibility of the polymer is extremely good. Further, since the polymer foams while melting, under moderate pressure, the volume increase due to foaming further increases the pressure, making it possible to achieve a high degree of dispersion.

The present invention will be explained in further detail.

The polymer was melt-kneaded with 1 to 5 PHR of a blowing agent at a temperature below the blowing agent decomposition temperature, extruded into fibers and then cut, or extruded into a sheet and then crushed to form fibers or fine powder. Add 25 to 200 parts by weight of this polymer fine powder or fiber to cement/(fine aggregate/
Coarse aggregate)/water = 100/200 to 400/10 to 50 parts by weight were mixed so as to be uniformly dispersed, poured into a mold of a desired shape, and degassed while being subjected to pressure treatment. . Thereafter, it was cured in a 100% RH atmosphere for 20 to 48 hours to bring it to a semi-hardened state.

Thereafter, the mixture was pressurized, heated, foamed, and molded to obtain the desired polymer cement concrete. It was found that the obtained polymer cement concrete had excellent compressive strength, tensile strength, etc. considering its weight.

Polymers that can be used in the present invention include polyolefins such as polyethylene and polypropylene, polyvinyl chloride, polyvinyl acetate, polystyrene, ethylene-vinyl acetate copolymers, thermoplastic resins such as rubbers such as NBR and SBR, or phenolic resins. , thermosetting resins such as epoxy resins (novolac type).

The cement is common portland cement,
Slag cement etc. can be used. The fine aggregate and coarse aggregate may be naturally occurring sand, gravel or man-made sandstone. Although the particle size depends on the dimensions of the material used, it is preferably as small as possible, and a maximum of 4 to 5 mm is the limit at which good results can be obtained.
The blowing agent is used to foam the polymer, and generally an organic blowing agent can be used, and it starts to decompose at a high enough temperature that it will not decompose when kneaded with the polymer. For example, sulfone hydrazide blowing agents such as P-P'oxybis(benzenesulfonyl hydrazide), 3-3' disulfone hydrazide diphenyl sulfone, and azo blowing agents such as azobisisobutyronitrile, azodicarbonamide, diethyl azodicarboxylate, etc. Foaming agents, etc., are preferably used, such as azodicarbonamide, which decomposes at as high a temperature as possible, because it makes it easy to adjust the foaming ratio of the final polymer cement concrete.

Further, in order to improve the affinity between the polymer and concrete, the strength can be further improved by using general inorganic fillers such as silica and calcium carbonate, and organic titanates such as reactive monoalkoxy titanates.

EXAMPLES In order to further clarify the present invention, Examples will be described.

Example Low density polyethylene (density 0.924, molecular weight
150000~200000) 5 parts by weight of azodicarbonamide is added to 100 parts by weight, and the die part temperature is
The mixture was extruded into a sheet using a single-screw extruder at 150° C., and the sheet was pulverized to obtain fine polyethylene powder having a particle size of about 50 μm. Separately, a cement mixture of ordinary Portland cement/sand/water in a weight ratio of 2/4/0.5 was prepared, and 70 parts by weight of the cement mixture was mixed with 30 parts by weight of the polyethylene and filled into a mold. In an atmosphere of 100%RH and 20℃
After curing for 30 hours, a degassing operation of applying a pressure of 20 kg/cm ² and returning to normal pressure was repeated 2 to 3 times. Thereafter, the temperature was raised to 180°C, and foam molding was performed by heating and pressing at 50Kg/cm ² .The product was cooled under pressure to 20°C and left to stand for further 8 hours. The obtained polymer cement concrete was made into square bars of 10 x 10 x 30 cm, with specific gravity
1.3, compressive strength 800Kg/cm ² , tensile strength 45Kg/cm ² , bending strength 60Kg/cm ² , elastic modulus (E1/3) 3.2×10 ⁵ , and has higher strength relative to its weight than ordinary cement concrete. It was hot. This polymer cement concrete can be easily bonded to each other with cement, rubber adhesive, etc., and has almost no water permeability (1/10 to 1/1
20), it was most suitable for use as a building material.

As described above, according to the present invention, the foamed polymer can be sufficiently filled into minute gaps in concrete, that is, even between concrete particles, so that the present invention is excellent in the following points.

(1) Lighter weight can be achieved while maintaining the same strength.

(2) Low water permeability.

(3) Excellent soundproofing properties.

(4) Excellent weather resistance, with little deterioration due to changes in temperature and humidity.

(5) Small creep at low loads.

Furthermore, since cement still has fluidity in a semi-hardened state, foaming is not suppressed and the weight can be sufficiently reduced. Furthermore, the molding cycle is relatively fast, and its industrial value is extremely large.

Claims (1)

[Claims] 1 Add an organic blowing agent whose decomposition temperature is lower than that of the polymer to the polymer, mix the crushed or beaten fine flakes or fibrous material with a composition consisting of cement, aggregate, and water, and mix the cement into a semi-hardened state. A method for producing polymer cement concrete, which is characterized by foaming the polymer while melting it by heating and applying pressure.