JPH0622978B2 - Asphalt sheet with friction reducing ability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an asphalt sheet having a friction-reducing ability, and more specifically, to prevent friction generated at the interface between concrete and concrete or a double wall structure such as concrete and steel plate. The present invention relates to an asphalt sheet that can be reduced.

[Conventional technology]

Those concrete cross or concrete and the steel plate or the like as the Young's modulus of the 10 ⁰ N / m ² or more is double-walled structure gives rise to friction interface when the double wall construction of the rapid temperature change or subsidence, very Large shear stresses can result, which can lead to cracks in the concrete wall. Therefore, conventionally, a method of inserting an asphalt-based compound layer (compound layer for long-term loading), which is a viscous fluid and has a smooth loading time of 10 ⁵ sec. Or more, is merely applied.

[Problems to be Solved by the Present Invention]

The frictional force generated at the interface between concretes or a double-walled structure such as a steel plate can be roughly calculated by the product Gε of the rigidity G and the displacement ε.

That is, Young's modulus of concrete (Young's modulus ≈ rigidity modulus G)
Is 2 × 10 ¹⁰ N / m ² (at 20 ° C) and the displacement ε is However, concrete wall length 100m, temperature difference 30 ℃, coefficient of thermal expansion 10
^{Assuming -5} / ℃, the change in length is 100m x 30 x 10 ^-5 = 30m
m = 3 × 10 ^-2 m The concrete wall thickness is 500 mm (= 5 × 10 ^-1 m).

Therefore, assuming that the shear stress is τ _c , it is as follows.

When such a frictional force is generated, it is presumed that the shear stress acting on the concrete wall becomes much larger than the tensile strength of the concrete and cracks occur in the concrete wall.

Therefore, the interface with a double wall structure has a small stiffness coefficient, that is, 4 × 10 ⁴ N / m ² (at 20 ° C.), loading time 10 ⁻² to 10 ²
Shear stress τ _A when a sheet with a sec. and a thickness of 2 mm is attached
When is calculated, it is as follows.

However, d: deviation length (3 × 10 ^-2 m) h: sheet thickness (2 × 10 ^-3 m) s: stiffness coefficient (4 × 10 ⁴ N / m ² ; at 20 ° C) ∴τ _A = 2 × 10 ⁵ N / m ² = 2 kg / cm ² .

The friction reduction rate in this case is However, if the friction reducing ability is small like this, it is not sufficient for countermeasures against temperature difference, ground subsidence or earthquakes, and a material having a high friction reducing rate is required.

The present invention interposes a sheet having a friction reducing ability at the interface between concretes or a double wall structure such as concrete and a steel plate as described above, whereby a crack or deformation in concrete due to temperature difference, ground subsidence, etc. To prevent.

[Means for Solving the Problems]

The present invention has a stiffness coefficient of 10 ³ to 10 ⁶ N / m ² (at 20 ° C.), which is effective for short-term loading sandwiched between concretes or an interface of a double wall structure of concrete and a steel plate, and a loading period of 10 ^-2 to 10 ⁴ s
ec. and a rubber asphalt-based compound layer having a thickness of 1 to 8 mm, and a stiffness coefficient effective for long-term loading of 10 ⁰ to 10 ³
N / m ² (at 20 ° C.), loading period 10 ⁵ to 10 ⁸ sec., And a laminated sheet with a friction reducing ability consisting of a thickness of 3 to 10 mm laminated with an asphalt-based compound layer having a thickness of 2 to 10 mm. is there.

The asphalt compound for short-term loading, which is used for steaming, has a sliding property, and when the loading time is 10 ^-2 to 10 ⁴ sec. And the stiffness coefficient is 10 ⁴ N / m ² or less, the amount of protrusion due to crimping is large, so rubber Use an asphalt compound with a softening point of 75 ° C or higher and a penetration of 70 (at 25 ° C).

A rubber asphalt compound for short-term loading improves thixotropy on straight asphalt (penetration 60 to 100) mixed with 8 to 12% of a polymer compound such as polystyrolbutadiene rubber (SBS). Therefore, it is desirable to add paraffin-based process oil, etc. as appropriate, which results in a loading time of 10 ^-2 to 10 ⁴ se.
c. Stiffness coefficient on the order of 10 ⁴ N / m ² is obtained.

Furthermore, the asphalt-based compound layer for long-term loading is
Loading time 10 ⁵ to 10 ⁸ sec., Stiffness coefficient 10 ⁰ to 10 ³ N / m ²
(At 20 ° C.), the present invention relates to a rubber asphalt-based compound layer having a slip property of 1 to 8 mm for a short-term loading and a rubber-asphalt-based compound layer having a sliding property for a long-term loading. It is a laminated sheet having a thickness of 3 to 10 mm in which a sheet having a thickness of 2 to 10 mm is laminated.

It is considered that by laminating asphalt-based compounds having different stiffness coefficients like the laminated sheet of the present invention, a layer having a small stiffness coefficient acts and causes displacement during the loading time, so that the shear stress can be reduced.

Fig. 3 shows an example of the relationship between the stiffness coefficient and loading time of long-term loading asphalt compound and short-term loading rubber asphalt compound (solid line in Fig. 3 indicates long-term loading, dotted line indicates As is clear from FIG. 3, the asphalt compound for long-term loading has a high stiffness coefficient in the elastic region and the viscoelastic region, and it is low in the viscous fluid region.

On the other hand, in the rubber asphalt compound for short-term loading, the stiffness coefficient is about 10 ⁴ N / m ² , and the stiffness coefficient is almost the same even in the viscous fluid region.

The present invention is a laminated sheet obtained by combining two asphalt-based compound layers for short-term loading and long-term loading, and at 10 ^-2 to 10 ⁴ sec. For loading, the stiffness coefficient of the rubber asphalt-based compound layer for short-term loading. (Dotted line in FIG. 3), while the loading time of 10 ⁵ to 10 ⁸ sec. Is the stiffness coefficient of the asphalt-based compound layer for long-term loading, and the stiffness coefficient of the laminated sheet of the present invention in all regions is independent of the loading time. 10 ⁰ to 10 ⁴ N / m ² (at20
A sheet having a friction reducing ability on the order of ° C) can be obtained.

[Work]

As described above, the laminated sheet of the present invention has a stiffness coefficient of 10 ^{0 in the} entire region from the elastic region to the viscous fluid region.
Since it can be up to 10 ⁴ N / m ² (at 20 ° C), by sandwiching this between concretes or at the interface between concrete and steel plate, it has the ability to reduce friction against temperature difference, ground subsidence, etc. be able to.

〔Example〕

FIG. 1 shows an embodiment of the present invention in which the laminated sheet 1 is
On the surface of the rubber asphalt compound layer 2 for short-term loading, an asphalt compound layer 3 for long-term loading having a sliding property is laminated, and a polypropylene nonwoven fabric 4 for protection is further laminated on the surface thereof. In FIG. 1, reference numeral 5 is a release paper for maintaining the adhesiveness of the rubber asphalt compound layer 2.

The properties of the asphalt compound for long-term loading and the rubber asphalt compound for short-term loading are as follows.

Asphalt compound for long-term loading Penetration (25 ℃) 35 ± 5 Softening point 75 ± 5 ℃ Low temperature flexibility 5 ℃ or more Stiffness coefficient 20 ℃ × 1 year 8N / m ² 20 ℃ × 30 days 9 × 10N / m ² 20 ℃ × 10 ^-2 1.5 × 10 ⁷ N / m ² Rubber asphalt compound for short-term loading Penetration (25 ℃) 70 ± 5 Softening point 84 ℃ Low temperature flexibility -30 ℃ Stiffness coefficient 20 ℃ × using state of the laminated sheet 1 of 1 year ^{8 × 10 3 N / m 2} 20 ℃ × 30 days ^{1 × 10 4 N / m 2} 20 ℃ × 10 -2 4 × 10 4 N / m 2 Figure 2 is the invention After peeling the release paper 5 of the laminated sheet 1 and adhering the rubber asphalt layer 2 to the molded concrete wall 6,
Concrete 7 is cast on the surface of the polypropylene nonwoven fabric 4 of the laminated sheet 1, the friction at the interface between the concrete wall 6 and the concrete 7 is significantly reduced, and the deformation of the concrete 7 due to temperature difference or ground subsidence or It can prevent cracks.

〔The invention's effect〕

(1) As described above, the present invention is a laminated sheet of asphalt-based compound layers having different stiffness coefficients for short-term loading and long-term loading in order to reduce friction at the interface between concretes or a double wall structure of concrete and a steel plate. , By sandwiching this at the interface, it is possible to reduce the shear stress due to seasonal temperature difference, ground subsidence or earthquake-induced shaking, thus preventing the deformation or cracking of concrete in double wall structure. be able to.

(2) Regarding the lining of tunnels and submerged linings laid in the ground or in the sea, if this sheet is sandwiched between the primary lining and the secondary lining, it behaves as a separating material, so long-term loading starts. Since the axial stress due to the primary lining is restrained by soil etc., only the cross section of the secondary lining bears the axial stress, and the compound layer effective for long-term loading acts so that it can be reduced.

The bending moment in the circumferential direction caused by short-term loading causes the compound layer effective for short-term loading to such an extent that relative sliding motion occurs so that the primary lining and the secondary lining remain integrated.

As described above, the stress acting in two directions has a long loading time and a short loading time. Therefore, it is an excellent advantage of this laminated sheet that the compound layers having different stiffness coefficients selectively correspond to each other.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the present invention, FIG. 2 is an explanatory view showing a usage state of the present invention, and FIG. 3 is a relationship diagram of a stiffness coefficient with respect to loading time. 1: Laminated sheet, 2: Rubber asphalt compound layer for short-term loading, 3: Asphalt compound layer for long-term loading, 4: Polypropylene nonwoven fabric, 5: Release paper, 6:
Molded concrete wall, 7: concrete.

Claims (1)

[Claims] 1. A stiffness coefficient of 10 ³ to 10 ⁶ N / m ² (at 20 ° C.) effective for short-term loading sandwiched between concretes or an interface of a double-walled structure of concrete and a steel plate, loading period of 10 ^-2
A rubber asphalt compound layer with a thickness of 1 to 8 mm in 10 ⁴ sec. And a stiffness coefficient of 10 ⁰ effective for long-term loading.
~ 10 ³ N / m ² (at 20 ° C), loading period 10 ⁵ ~ 10 ⁸ sec., And a friction reducing ability consisting of a thickness of 3-10 mm laminated with a 2-10 mm thick asphalt compound layer. Asphalt sheet.