JPS5917068B2 - Resin-impregnated hydraulic object mainly composed of shirasu and alumina cement - Google Patents

Description

Detailed Description of the Invention The present invention utilizes volcanic ejecta called shirasu or pozzolan, which exists in large quantities in volcanic areas in southern Kyushu and other parts of Japan, and uses this and alumina cement as raw materials to absorb water into a hydraulic object. It is characterized by being mixed with or impregnated with a synthetic resin in order to eliminate water resistance and water permeability.

Whitebait, which is scattered in large quantities in volcanic areas, forms soft soil that can collapse during the rainy season and cause pollution, and there are high hopes for the development of the use of whitebait, especially in the Kagoshima region, where there are many whitebait. 0 Shirasu's mineral composition is 50-78% volcanic glass.
, 20-50% feldspar and quartz, and the chemical analysis value is S 0260-75.

Al20313-16%, Fe as other trace components
203 about 2.6%, CaO about 2.8%, MgO about 0.5%, Na2O about 4.2%, and 20 about 2.2% others.

The silica and alumina contained in this volcanic glass, that is, the amorphous part, are mixed with cement and become a factor in hardening when water is added. Among these, alumina is the Ca0 contained in the cement when general-purpose cement such as Portland cement is added. =SiO□m Ca5O, reacts with ettringite Ca12A 14 (OH)24 (S
Alumina cement precipitates into hardened cement as acicular crystals of O4)a*50H20, and its internal stress causes the cement phase to collapse from within, significantly reducing the strength of the hydraulic object and making it completely unusable. For example, component A1□03CaO8i02Fe203 Other% 56.0 33.4 3.3 2.6 0
．． As shown in analysis example 7, it was discovered that calcium aluminate was produced by mixing alumina and calcium oxide as main components with the above-mentioned shirasu containing silica and alumina as main components and adding water. In order to remove the water absorption and water permeability of a hydraulic object, a synthetic resin such as polyethylene is mixed into the raw material mixture or impregnated into the molded product after hardening.

The present invention is made by mixing shirasu and alumina cement as described above, kneading it with water, and hardening the hydraulic object by mixing a synthetic resin with the raw material mixture, or by impregnating the synthetic resin from the outer peripheral surface after molding. Synthetic resins used here include polyethylene, acrylic resin-melamine resin mixture, methyl methacrylate-toracrylonitrile copolymer, acrylic-urea copolymer, methyl methacrylate polymer, polystyrene, and other non-water-soluble synthetic resins. A resin, preferably an aqueous dispersion thereof, is used.

To explain the example below, Shirasu (volcanic ejecta)
is finely ground, and this shirasu powder is mixed with alumina cement in an appropriate ratio (for example, the weight ratio of alumina cement to shirasu is 10 to 50%), kneaded with water, filled into a mold, and hardened in air. For hydraulic objects, a 45% aqueous dispersion of modified acrylic is added to a raw material mixture with water added in an amount of 2 to 3% of the weight of Shirasu in terms of solid content, or 1 to 2 benzoyl peroxide is added to a monomer or oligomer of methyl methacrylate. The cured hydraulic object is immersed in a solution containing oxide as a polymerization initiator, impregnated under pressure or vacuum, and then heated to about 80° C. for radical polymerization.

Alumina cement is a semi-stable Cab due to water use reaction.
Al2O3* 10H20 and 2 Ca O, AI
203 g8H20 and stable 3CaO, Al2O3
, 6H20 and other aluminate compounds.

Among these, the metastable aluminate compound is Ca0vA120;3t10H2()”3CaOt
AJ203 t6H20+2A1203.6H20+2
A1203>Ha0+18H20 The transition is made to a stable aluminate compound such as A1203>Ha0+18H20, and as a result, the voids between crystal particles become larger, so that the strength of a hydraulic product made only of alumina cement gradually decreases.

Here, when Shirasu powder is mixed with alumina cement and a hydraulic reaction is performed, a large amount of A1□03 is present in Shirasu, resulting in stable calcium aluminate 3CaO.

Since a gel of Al2O3, 6H20 is formed and this fills the voids between unreacted particles, the molded product becomes a strongly cured product, and the strength tends not to decrease over a long period of time but rather to increase.

When molded into a desired shape using a mold with a smooth surface, a glossy hardened film of calcium aluminum silicate CaAl [AI(SO4)2] is formed on the surface of the molded product.

Furthermore, by mixing a synthetic resin into the raw material or coating and impregnating it on the surface of a molded cured product, water absorption and water permeability can be removed without damaging the properties of the water cured product, resulting in seawater resistance,
Blocks, tiles, boards, etc. with excellent chemical resistance and fire resistance can be easily obtained by molding by cement pouring. It can produce excellent effects such as being able to utilize whitebait, which has been desired to be developed, and to provide it at a low cost.

Claims (1)

[Claims] 1 A hydraulic object made by mixing whitebait powder obtained by crushing whitebait (volcanic ejecta) and alumina cement in an appropriate ratio, kneading it with water, filling it into a mold, and hardening it in the air, using synthetic resin as the raw material. A resin-impregnated hydraulic object whose main components are shirasu (volcanic ejecta) and alumina cement, and is characterized by being mixed into a compound or impregnated with a synthetic resin from the outer peripheral surface after molding.