JPH0655475B2 - 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 alloy, steel plate, glass fiber reinforced cement, asbestos cement, etc. have been used as the floor material constituting the floating floor. Aluminum alloy and steel flooring
Although it has high strength and excellent durability, when it walks on the constructed floating floor, a loud footstep is generated. On the other hand, a floor material made of glass fiber reinforced cement or asbestos cement is preferable because the footsteps during walking are small and the walking feeling is good. However, flooring made of glass fiber reinforced cement has low strength and is easily damaged. Floor materials made of asbestos cement have relatively high strength, but they are brittle and lack impact resistance.

In order to solve these drawbacks, cement moldings containing reinforcing fibers such as carbon fibers and aramid fibers have been proposed as floor materials (cement / concrete).
No. 467.Jan. 1986, p22-29). However, the cement molded product to which these reinforcing fibers are simply added has high strength but also low impact resistance.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a cement molded product having high strength and excellent impact resistance. is there. Another object of the present invention is to provide a cement molded product capable of reducing footsteps during walking.

(Means for Solving Problems) In the present invention, a cement molded product as a flooring material is configured in two layers,
It was completed based on the inventor's knowledge that a cement molded product having high strength and excellent impact resistance can be obtained by including reinforcing fibers having different elastic moduli in the upper layer and the lower layer.

The cement molded product of the present invention is a cement molded product having a two-layer structure used for a floating floor material, and the upper layer has a tensile elastic modulus of 50.
The reinforcing fiber (A) of less than GPa is contained, and the lower layer contains the reinforcing fiber (B) of which tensile elastic modulus is 50 GPa or more, whereby the above object is achieved.

If the tensile modulus of the reinforcing fiber (A) is 50 GPa or more, the desired impact resistance of the cement molded product cannot be obtained. Reinforcing fiber
If the tensile elastic modulus of (B) is less than 50 GPa, the desired strength of the cement molded product cannot be obtained.

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 2 times, the desired impact resistance of the cement molded product cannot be obtained. If it exceeds 10 times, the desired strength of the cement molded product cannot be obtained.

Examples of the reinforcing fiber (A) include vinylon fiber, polypropylene fiber, polyethylene fiber, nylon fiber, and acrylic fiber. Reinforcing fiber (A) is the upper layer, 0.2 ~ 6 wt%,
It is preferably contained in the range of 0.3 to 4% by weight. If it is less than 0.2% by weight, the desired impact resistance of the cement molded product cannot be obtained. When it exceeds 6% by weight, the dispersibility of the reinforcing fiber is deteriorated and the impact resistance of the cement molded product is rather deteriorated.

Examples of the reinforcing fiber (B) include carbon fiber, asbestos fiber,
There is aramid fiber. Reinforcing fiber (B) is 0.5 ~ 6 in the upper layer
The content is in the range of, preferably 0.6 to 4% by weight. If it is less than 0.5% by weight, the desired strength of the cement molded product cannot be obtained. When it exceeds 6% by weight, the dispersibility of the reinforcing fiber is deteriorated and the strength of the cement molded product is rather lowered.

The above-mentioned reinforcing fibers (A) and (B) are usually chopped fibers. 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, it becomes difficult to uniformly mix the reinforcing fiber and the cement, and thus the strength of the obtained cement molded product tends to be low. When the length is less than 3 mm,
Even if these fibers are contained, it is difficult to obtain desired impact resistance and strength.

The upper and lower layers contain cement (Portland cement), reinforcing fibers, water, and if necessary, additives.

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 according to the blending amount of reinforcing fibers, 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 cement molded product of the present invention is obtained, for example, by dehydration press molding. In order to obtain the cement molded product of the present invention by dehydration press molding, the upper layer material and the lower layer material are premixed by, for example, an omni mixer, and then a predetermined amount is weighed. Next, one of the upper layer material and the lower layer material is put into the lower mold and subjected to dehydration press molding for a predetermined pressure and time. After molding, the mold is opened, the other material is charged, and the same dehydration press molding is performed, and the upper layer and the lower layer are integrated to obtain a cement molded body. In the dehydration press molding, it is preferable to use a mold having drainage pores on the mold surface.

(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. The tensile elastic modulus of the reinforcing fiber was measured according to JIS R 7601.

(1) Upper layer Portland cement 100 parts by weight Fly ash 30 parts by weight Vinylon fiber (diameter 16 mm, length 10 mm, tensile elastic modulus 37 GP
a, 0.6% by weight of the cement compact) 1 part by weight Methyl cellulose 0.2 parts by weight Water 45 parts by weight (2) Lower layer Portland cement 100 parts by weight Aramid fiber (HM-50, diameter 12 mm, length 6 mm, tensile elastic modulus 71 GPa, Teijin, 1.2% by weight of the weight of the cement molded product) 2 parts by weight Methylcellulose 0.2 parts by weight Fly ash 30 parts by weight Water 45 parts by weight (3) Mold Processed to obtain a 300 mm x 300 mm plate-shaped molded product ing. It consists of two parts, an upper mold and a lower mold.
There is a drainage pore of 1.2 mm in diameter every 5 mm × 5 mm. A filter cloth is attached to the surface of the upper mold.

The materials for the upper layer were mixed with an omni mixer. About 5 kg of this mixture was fed to the lower mold of the mold. When the mold was opened after press molding with a pressure of 20 kg / cm ² , the compact adhered to the lower mold. The materials for the lower layer were then mixed with an omni mixer. About 1 kg of this mixture was supplied to the upper surface of the above-mentioned molded body, and was dehydrated and press-molded with the above-mentioned molded body at a pressure of 40 kg / cm ² for 60 seconds. The obtained cement compact was temporarily cured in a steam atmosphere at 60 ° C for 24 hours and then at room temperature.
I was cured for 30 days. 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.

(B) Evaluation of molded body The four corners of the cement molded body obtained in (A) were supported by a cubic steel piece with a side of 2 cm so that the lower layer was located on the lower surface. 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, in the center of the upper surface of the molded body that also supported the four corners,
A 1 kg steel ball was dropped naturally from a height of m, and the state of fracture of the compact was observed (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 Molded in the same manner as in Example 1 except that carbon fiber (PAN-based, diameter 7 μm, length 12 mm, tensile elastic modulus 235 GPa) was used as the lower layer reinforcing fiber (B) instead of the aramid fiber. The body was prepared. 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 Approximately 4.2 kg of upper layer material was fed, and lower layer material was approximately 1.8 kg.
A molded body was prepared in the same manner as in Example 1 except that kg was supplied. The layer thickness of the lower layer of the molded body was about 9 mm, and the layer thickness of the upper layer was about 21 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 820 kg, and it was not broken in the falling ball test.

Example 4 Approximately 5.3 kg of upper layer material was fed, and lower layer material was approximately 0.7 kg.
A molded body was prepared in the same manner as in Example 1 except that kg was supplied. The layer thickness of the lower layer of the compact was about 3.5 mm, and the layer thickness of the upper layer was about 26.5 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 750 kg, and it was not broken in the falling ball test.

Example 5 As a reinforcing fiber (A) for the upper layer, an acrylic fiber (diameter 18 μm, length 12 mm, tensile elastic modulus 8 GP was used instead of vinylon fiber.
A molded body was prepared in the same manner as in Example 1 except that 6 parts by weight of (a) was contained (3.6% by weight of cement molding weight). 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 780 kg, and it was not broken in the falling ball test.

Example 6 A molded body was prepared in the same manner as in Example 1 except that 1 part by weight (0.6% by weight of the cement molded body) of aramid fiber was contained. 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 720 kg, and it was not broken in the falling ball test.

Example 7 A molded body was prepared in the same manner as in Example 1 except that 7 parts by weight of aramid fiber (4.2% by weight of the cement molded body) was contained. 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 810 kg, and it was not broken in the falling ball test.

Example 8 A molded body was prepared in the same manner as in Example 1 except that 0.5 part by weight of vinylon fiber (0.3% by weight of the cement molded body) was contained. 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 790 kg, and it was not broken in the falling ball test.

Example 9 A molded product was prepared in the same manner as in Example 1 except that 1 part by weight of vinylon fiber was added and 0.2 part by weight of carbon fiber was further added as the reinforcing fiber for the upper layer. 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 10 A molded article was prepared in the same manner as in Example 1 except that 0.5 part by weight of asbestos fiber (length: 5 mm, tensile elastic modulus: 170 GPa) and 1.5 part by weight of aramid fiber were used as the lower layer reinforcing fiber (B). Prepared. 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 810 kg, and it was not broken in the falling ball test.

Example 11 Approximately 5.6 kg of upper layer material is fed, and lower layer material is approximately 0.4
A molded body was prepared in the same manner as in Example 1 except that kg was supplied. The layer thickness of the lower layer of the molded body was about 2 mm, and the layer thickness of the upper layer was about 28 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 600 kg, and it was not broken in the falling ball test.

Example 12 About 3.6 kg of the material for the upper layer was supplied, and about 2.4 kg of the material for the lower layer was supplied.
A molded body was prepared in the same manner as in Example 1 except that kg was supplied. The thickness of the lower layer of the compact was about 12 mm, and the thickness of the upper layer was about 18 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 850 kg, but cracks occurred in the lower layer in the falling ball test.

Comparative Example 1 About 6 kg of the lower layer material of Example 1 was supplied to the lower mold of the mold of Example 1 and subjected to dehydration press molding for 60 seconds at a pressure of 40 kg / cm ² . The obtained cement molded product is placed in a steam atmosphere at 60
After primary curing at ℃ for 24 hours, it was further cured at room temperature for 30 days. The layer thickness of the molded body was about 30 mm.

When the obtained molded product was evaluated by the same method as in Example 1, the breaking load in the central concentrated load test was 900 kg, but cracks occurred on the lower surface of the molded product in the falling ball test.

Comparative Example 2 A molded body was prepared in the same manner as Comparative Example 1 except that the lower layer material of Example 2 was used. The layer thickness of the molded body was about 30 mm.

When the obtained molded product was evaluated by the same method as in Example 1, the breaking load in the central concentrated load test was 920 kg, but it was broken in the falling ball test.

Example 3 A molded body was prepared in the same manner as in Comparative Example 1 except that the upper layer material was used instead of the lower layer material. The layer thickness of the molded body was about 30 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 500 kg, and it was not broken in the falling ball test.

Comparative Example 4 Instead of vinylon fiber, alkali resistant glass fiber (diameter 13
A molded body was prepared in the same manner as in Example 1 except that the thickness was 10 μm, the tensile elastic modulus was 69 GPa). 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 product was evaluated by the same method as in Example 1, the breaking load in the central concentrated load test was 810 kg, but cracks occurred in the falling ball test.

As is clear from Examples and Comparative Examples, the cement molded product of the present invention is excellent in both strength and impact resistance. A cement molded product obtained only with the lower layer material containing the reinforcing fiber (B) has high strength but lacks impact resistance. The cement molded product obtained only by the upper layer material containing the reinforcing fiber (A) has low impact strength although it has high impact resistance. A cement molded product using alkali resistant glass fiber instead of vinylon fiber cannot obtain desired impact resistance. Also in the cement molded product of the present invention, when the ratio of the layer thickness of the upper layer to the lower layer is less than 2 times, the impact resistance decreases, and when it exceeds 10 times,
Strength is impaired.

(Effects of the Invention) As described above, the cement molded product of the present invention has a tensile elastic modulus.
It has a two-layer structure consisting of an upper layer containing reinforcing fibers (A) of less than 50 GPa and a lower layer containing reinforcing fibers (B) having a tensile elastic modulus of 50 GPa or more, so it has high strength and excellent impact resistance. 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 (10)

[Claims] 1. A cement molded product having a two-layer structure used for a floating floor material, the upper layer containing a reinforcing fiber (A) having a tensile elastic modulus of less than 50 GPa.
A cement molded product whose lower layer contains a reinforcing fiber (B) having a tensile elastic modulus of 50 GPa or more. 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, wherein the reinforcing fiber (A) is at least one of vinylon fiber, polypropylene fiber, polyethylene fiber, nylon fiber and acrylic fiber. 4. The cement molded product according to claim 1, wherein the reinforcing fiber (B) is at least one of carbon fiber, asbestos fiber and aramid fiber. 5. The cement molded product according to claim 1, wherein the reinforcing fiber (A) has a length of 3 to 20 mm. 6. The cement molded product according to claim 1, wherein the reinforcing fiber (B) has a length of 3 to 20 mm. 7. The reinforcing fiber (A) is added to the upper layer in an amount of 0.2 to 6
The cement molded product according to claim 1, wherein the cement molded product is contained in a weight% range. 8. The reinforcing fiber (B) is added to the lower layer in an amount of 0.5 to 6
The cement molded product according to claim 1, wherein the cement molded product is contained in a weight% range. 9. At least one of the upper layer and the lower layer,
The cement molded product according to claim 1, which contains an aggregate such as sand or fly ash. 10. The cement molded product according to claim 1, which is obtained by dewatering press molding using a mold having drainage pores on the mold surface.