JPH0622980B2 - Cement molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is used for a cement molded product, particularly a computer room with a high wiring density such as wiring cables and cords, or an office room in which various office machines are arranged. The present invention relates to a cement molded product used for a floating floor material, which is formed on a floor with an appropriate space by closely connecting and fixing a plurality of sheets on the same plane.

(Prior Art) With the progress of office automation, there are increasing opportunities to install a large number of office equipment and communication equipment in an office. Therefore, wiring and piping must be laid on the floor. In order to make this laying work easier, a floating floor is erected with a proper space on the floor.

Conventionally, aluminum alloys, steel plates, asbestos cement, etc. have been used as floor materials that make up floating floors. The floor material made of aluminum alloy or steel plate has high strength and is excellent in durability, but when walking on the constructed floating floor, a loud footstep is generated. On the other hand, a floor material made of asbestos cement reduces footsteps when walking, but is heavy, and therefore requires a great deal of effort when changing the wiring during or after construction. Moreover, asbestos cement is brittle and lacks impact resistance.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and an object of the present invention is to reduce the footstep noise during walking while being lightweight and having excellent impact resistance. It is to provide a cement molded product.

(Means for Solving Problems) The cement molded product of the present invention is a cement molded product having a two-layer structure used for a floating floor material, in which the upper layer contains hollow lightweight aggregate and the lower layer is reinforced. It contains fibers, whereby the above-mentioned object is achieved.

The layer thickness of the upper layer is set to 2 to 10 times, preferably 3 to 9 times the layer thickness of the lower layer. If it is less than double, it will be difficult to achieve sufficient weight reduction of the cement compact. If it exceeds 10 times, it is difficult to obtain the desired impact resistance.

Examples of the hollow lightweight aggregate contained in the upper layer include shirasu balloon, glass balloon, anti-firestone foam, obsidian foam, and clay foam. The diameter of this aggregate is about 0.01 ~
5 mm, and the specific gravity is about 0.05-1.0. The hollow lightweight aggregate is contained in an amount of 3 to 30 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of cement. When it is less than 3 parts by weight, it is difficult to obtain the desired lightweightness and impact resistance of the cement molded product. If it exceeds 30 parts by weight, it becomes difficult to disperse the aggregate in the cement, so that the impact resistance of the obtained cement compact tends to deteriorate rather.

The upper layer contains cement (Portland cement), hollow lightweight aggregate, water and, if necessary, additives. Furthermore, impact resistance is improved by adding organic fibers. The amount of water is adjusted according to the compounding amount of the hollow lightweight aggregate, and is usually 40 to 100 parts by weight, preferably 42 to 80 parts by weight, relative to 100 parts by weight of cement. As an additive,
Methylcellulose is used as a dispersion aid for aggregates and as a fluidity improver during molding, and 0.02 to 2 parts by weight is added to 100 parts by weight of cement. As the organic fiber, for example, synthetic fiber such as vinylon fiber, polypropylene fiber, polyethylene fiber, nylon fiber or natural organic fiber is used. The tensile elastic modulus of the organic fiber is preferably 50 GPa or less. If it exceeds 50 GPa, the impact resistance of the cement compact tends to decrease. The content of the organic fiber in the cement compact is 0.1 to 2% by weight, preferably 0.2 to 1.8% by weight.

The reinforcing fibers contained in the lower layer include, for example, carbon fibers, asbestos fibers, and aramid fibers. The reinforcing fiber is contained in the lower cement molded product in an amount of 6% by weight or less, preferably 5% by weight or less. When it exceeds 6% by weight, it becomes difficult to disperse the reinforcing fiber in the cement, and hence the impact resistance of the obtained cement molded product is rather lowered.

In the lower layer, in addition to cement (Portland cement) and reinforcing fibers, sand, aggregate such as fly ash, water, and additives are contained.

Aggregates such as sand and fly ash are used as needed, and are contained in an amount of 100 parts by weight or less, preferably 80 parts by weight or less, relative to 100 parts by weight of cement. If it exceeds 100 parts by weight, the strength of the obtained cement molded product tends to decrease. The amount of water is adjusted depending on the amount of the reinforcing fiber compounded, and is usually 30 to 80 parts by weight, preferably 32 to 70 parts by weight, based on 100 parts by weight of cement. Similar to the upper layer, as an additive, a dispersion aid for aggregates and methyl cellulose as a fluidity improving agent at the time of molding are used, and 0.02 to 2 parts by weight is added to 100 parts by weight of cement.

The organic fiber and the reinforcing fiber are usually in the form of chop fiber. This fiber is a filament having a length of 3 to 20 mm, preferably 3 to 15 mm and a diameter of 2 to 20 μm. When the length exceeds 20 mm, the strength at the interface between the upper layer and the lower layer decreases, and therefore the strength of the obtained cement compact tends to decrease. If the length is less than 3 mm, it is difficult to obtain the desired improvement in impact resistance even if these fibers are contained.

The cement molded product of the present invention is obtained by dehydration press molding. In dewatering press molding, there are basically 2 types of lower mold and upper mold.
A mold including three parts, or a three-point mold including a lower mold, an upper mold, and a frame-shaped side mold that forms a side surface is used. Numerous drainage pores are provided on the mold surface of either the lower mold or the upper mold. Due to these pores, excess water is discharged out of the system during molding. In this case, the discharge of water is promoted by connecting the pores to a vacuum pump and reducing the pressure inside the mold. The material for forming the upper layer and the lower layer is filled in a mold and pressurized while discharging water with a vacuum pump or the like. By doing so, a flow of water across the interface is generated at the interface between the upper layer and the lower layer, the cement component and the like flow at the same time as the water, and the adhesiveness between the upper layer and the lower layer is improved at this interface. For example, when there are pores for dehydration on the mold surface on the lower layer side, excess water and air contained in the material on the upper layer side crosses the interface between the upper layer and the lower layer simultaneously with pressure compression, and It is discharged from the pores. In this way, excess water and air contained in the materials of the upper and lower layers are discharged at the same time as compression, consolidated and molded. As a result, at the interface between the upper layer and the lower layer, although one or both of them contain a large amount of reinforcing fibers, and the upper layer is supplied with a different material system having a different composition including the lightweight aggregate, Like
Adhesive integration at the interface is achieved due to cement components, etc., as well as excess water moving across the interface. The pressing pressure is 20 to 80 kg / cm ² , and preferably 25 to 70 kg / cm ² . If it is less than 20 kg / cm ² , consolidation of the obtained cement molded product will be insufficient and the strength will tend to decrease. 80 kg /
When it exceeds cm ² , the hollow lightweight aggregate is destroyed, and it is difficult to achieve the desired weight reduction. Moreover, it is difficult to reduce footsteps when walking with the hollow lightweight aggregate.

(Examples) The present invention will be described below with reference to Examples.

Example 1 (A) Preparation of molded body The following substances were used as materials for the upper layer and the lower layer. The mold used had the following shape.

(1) Upper layer Portland cement 100 parts by weight Shirasu balloon (specific gravity 0.5, diameter 0.04 to 0.08 mm) 10 parts by weight Methylcellulose 0.2 parts by weight Water 60 parts by weight (2) Lower layer portland cement 100 parts by weight Aramid fiber (HM- 50, length 6 mm, tensile modulus 71 GPa,
Made by Teijin Co., Ltd., 1.2 wt% of the weight of the cement compact
2 parts by weight Methylcellulose 0.2 parts by weight Fly ash 30 parts by weight Water 45 parts by weight (3) Mold Processed so as to obtain a 300 mm × 300 mm molded body. It consists of two parts, an upper mold and a lower mold.
Drainage pores having a diameter of 1.2 mm are provided at a rate of 1 per 5 mm. A filter cloth is attached to the surface of the upper mold.

The materials for the lower layer were mixed with an omni mixer. About 1.0 kg of this mixture was fed to the lower mold of the mold. After press molding with a pressure of 20 kg / cm ² , when the mold was opened, the compact adhered to the upper mold. The materials for the upper layer were then mixed with an omni mixer. About 4 kg of this mixture was supplied to the lower mold of the mold, and was dehydrated and press-molded for 60 seconds at a pressure of 40 kg / cm ² together with the above-mentioned molded body. The obtained cement compact was subjected to primary curing at 60 ° C for 24 hours in a steam atmosphere, and then at room temperature for 30 days. The weight of the molded body was about 3.8 kg. The layer thickness of the lower layer of the molded body was about 5 mm, and the layer thickness of the upper layer was about 25 mm. In the market for floating flooring materials for office automation, where weight reduction is required, the weight is about 40
It is required to have a value of up to 45 kg / m ² or less. In this example and the following comparative examples, the weight is 30 cm × 30 cm as a guide,
The thing of about 3.7-4.0 kg was evaluated.

(B) Evaluation of molded product The four corners of the cement molded product obtained in (A) were supported by cubic steel pieces with a side of 2 cm. A load was applied to the central part of this compact with a cylindrical steel presser of φ50 mm to determine the breaking load (central concentrated load test).

On the other hand, the same cement compact was placed horizontally on 10 cm thick sand, and a 1 kg steel ball was dropped naturally from a height of 1 m to observe the state of fracture of the compact (falling ball test).

As a result, the breaking load in the central concentrated load test was 800 kg,
And it did not break in the falling ball test.

Example 2 Instead of aramid fiber, carbon fiber (PAN type, diameter 9μ
m, length 12 mm, manufactured by Toho Rayon Co., Ltd.) A molded body was prepared in the same manner as in Example 1. The weight of the obtained molded body was about 3.9 kg. The layer thickness of the lower layer of the molded body was about 5 mm, and the layer thickness of the upper layer was about 25 mm.

When the obtained molded body was evaluated by the same method as in Example 1, the breaking load in the central concentrated load test was 800 kg, and it was not broken in the falling ball test.

Example 3 Shirasu balloon was set to 25 parts by weight, and the amount of water used in the upper layer was 70
A molded body was prepared in the same manner as in Example 1 except that the weight part was used. The weight of the obtained molded body was about 3.7 kg. The lower layer of the molded body had a thickness of about 5 mm, and the upper layer had a thickness of about 29 mm.

The obtained molded body was evaluated by the same method as in Example 1. As a result, the breaking load in the central concentrated load test was 850 kg, and it was not broken in the falling ball test.

Example 4 Vinylon fiber (diameter 13 μm, length 10 mm,
1 part by weight (manufactured by Unitika Ltd.) (0.
A molded body was prepared in the same manner as in Example 1 except that the content was 7% by weight. The weight of the obtained molded body is about 3.8.
It was kg. The layer thickness of the lower layer of the molded body was about 5 mm, and the layer thickness of the upper layer was about 25 mm.

The obtained molded product was evaluated by the same method as in Example 1. As a result, the breaking load in the central concentrated load test was 810 kg, and it was not broken in the falling ball test.

Example 5 A molded product was prepared in the same manner as in Example 1 except that the supply amount of the lower layer material was about 2.5 kg and the supply amount of the upper layer material was about 2.1 kg. The weight of the obtained molded body was about 3.8 kg. Moreover, the layer thickness of the lower layer of the molded body is about 12 m.
m, and the layer thickness of the upper layer was about 14 mm.

The obtained molded product was evaluated by the same method as in Example 1. As a result, the breaking load in the central concentrated load test was 710 kg, and in the falling ball test, some cracks were formed in the upper falling ball portion, but they were not broken.

Comparative Example 1 A molded body was prepared in the same manner as in Example 1 except that the Shirasu balloon was not used and the supply amount of the upper layer was 3.7 kg. The weight of the obtained molded body was about 3.8 kg. The lower layer of the molded body had a thickness of about 5 mm, and the upper layer had a thickness of about 16 mm.

When the obtained molded body was evaluated by the same method as in Example 1, the breaking load in the central concentrated load test was 300 kg, and the breaking load was broken in the falling ball test.

Comparative Example 2 A molded body was prepared in the same manner as in Example 1 except that aramid fiber was not used. The weight of the obtained molded body was about 3.7 kg. Moreover, the layer thickness of the lower layer of the molded body is about 5 m.
m, and the layer thickness of the upper layer was about 26 mm.

When the obtained molded body was evaluated by the same method as in Example 1, the breaking load in the central concentrated load test was 250 kg, and the breaking conditions were broken apart. In the drop ball test, it split into two.

Comparative Example 3 A molded body was prepared in the same manner as in Example 1 except that the upper mold used was a mold having no pores. In this case, since dehydration during molding was performed from the mating surface of the mold, molding took 5 minutes. The weight of the obtained molded body was about 3.
It was 9 kg.

When the obtained molded body was evaluated by the same method as in Example 1, the breaking load in the central concentrated load test was 300 kg, and the breaking condition was breaking at the interface between the upper layer and the lower layer. In the falling ball test, there was a crack reaching the lower surface.

Comparative Example 4 Example 1 except that the length of the aramid fiber was 30 mm.
A molded body was prepared in the same manner as in. The weight of the obtained molded body was about 3.8 kg. The layer thickness of the lower layer of the molded body was about 5 mm, and the layer thickness of the upper layer was about 25 mm.

When the obtained molded body was evaluated by the same method as in Example 1, the breaking load in the central concentrated load test was 280 kg, and the breaking condition was breaking at the interface between the upper layer and the lower layer. In the falling ball test, there was a crack reaching the lower surface.

Comparative Example 5 A molded body was prepared in the same manner as in Example 4 except that the length of the aramid fiber was 30 mm and the length of the vinylon fiber was 30 mm. The weight of the obtained molded body was about 3.9 kg. The layer thickness of the lower layer of the molded body was about 5 mm, and the layer thickness of the upper layer was about 25 mm.

When the obtained molded body was evaluated by the same method as in Example 1, the breaking load in the central concentrated load test was 280 kg, and the breaking condition was breaking at the interface between the upper layer and the lower layer. In the falling ball test, there was a crack reaching the lower surface.

Comparative Example 6 A molded body was prepared in the same manner as in Example 1 except that the lower layer material was supplied to the lower mold without using the upper layer material. The obtained molded body weighed about 3.8 kg and had a thickness of 21 mm.

The obtained molded product was evaluated by the same method as in Example 1. As a result, the breaking load in the central concentrated load test was 450 kg, and there was a crack reaching the lower surface in the falling ball test.

Comparative Example 7 A molded body was prepared in the same manner as in Example 1 except that the aramid fiber was 13 parts by weight (8% by weight of the cement molded body). The weight of the obtained molded body is about 3.8 kg, and
The lower layer of the compact has a thickness of about 7 mm, and the upper layer has a thickness of about 25 mm.
It was mm.

When the obtained molded body was evaluated by the same method as in Example 1, the breaking load in the central concentrated load test was 280 kg, and the breaking condition was breaking at the interface between the upper layer and the lower layer. In the falling ball test, there was a crack reaching the lower surface.

Comparative Example 8 A molded body was prepared in the same manner as in Example 1 except that the amount of water used in the upper layer was 35 parts by weight and the upper layer material was supplied to the lower mold by about 3.2 kg. The weight of the obtained molded body was about 3.
It was 8 kg. The lower layer of the molded body had a thickness of about 6 mm, and the upper layer had a thickness of about 25 mm.

When the obtained molded body was evaluated by the same method as in Example 1, the breaking load in the central concentrated load test was 290 kg, and the breaking condition was breaking at the interface between the upper layer and the lower layer. In the falling ball test, there was a crack reaching the lower surface.

As is clear from Examples and Comparative Examples, the cement molded product of the present invention is lightweight and has excellent impact resistance. Cement compacts that do not contain hollow lightweight aggregates lack lightness and impact resistance. Cement moldings containing no aramid fibers and cement moldings containing aramid fibers with a length of 30 mm do not have the desired impact resistance. The cement compact with a single-layer structure obtained by using only the lower layer material is insufficient in weight reduction. If the cement compact is molded using a mold that does not have pores on the cavity surface, dehydration during molding is difficult. As a result, water and air remain at the interface between the upper and lower layers, which reduces the strength of the compact.

(Effect of the Invention) Since the cement molded product of the present invention has a two-layer structure of the upper layer containing the hollow lightweight aggregate and the lower layer containing the reinforcing fiber in this manner, it is lightweight and has excellent impact resistance. There is. No loud footsteps are produced when walking on this cement compact. As a result, the cement molded product of the present invention can be effectively used as a floor material constituting a floating floor.

Claims (9)

[Claims] 1. A cement molded product having a two-layer structure for use in a floating floor material, wherein the upper layer contains hollow lightweight aggregate and the lower layer contains reinforcing fibers. 2. The cement molded product according to claim 1, wherein the layer thickness of the upper layer is 2 to 10 times the layer thickness of the lower layer. 3. The cement molded product according to claim 1, which is obtained by dehydration press molding using a mold having drainage pores on the mold surface. 4. The cement molded product according to claim 1, wherein the reinforcing fiber is at least one of carbon fiber, asbestos fiber and aramid fiber. 5. The cement molded product according to claim 1, wherein the hollow lightweight aggregate is contained in an amount of 3 to 30 parts by weight based on 100 parts by weight of cement. 6. The cement molded product according to claim 1, wherein the reinforcing fiber is contained in an amount of 6% by weight or less. 7. The cement molded product according to claim 1, wherein the reinforcing fibers have a length of 3 to 20 mm. 8. The cement molded product according to claim 1, wherein the upper layer contains an organic fiber. 9. The cement molded product according to claim 1, wherein the lower layer contains an aggregate such as sand or fly ash.