Hello, everyone.
This is Enta.
Recently, in private construction projects, I’ve been asked to take measures regarding Otani stone.
While I do specialize in measures to counter soil pressure and heavy rain, you mean the surface?!
Slope stabilization isn't really a big deal, but when it comes to preventing rock weathering, what are we slope specialists supposed to do?!
What exactly is Otani Stone?
I think a lot of slope contractors feel this way, so I'll just copy and paste the AI's opinion.
The History of Otani Stone
● Tuff quarried in Ōya-chō, Utsunomiya City, Tochigi Prefecture.
It consists of volcanic deposits from about 15 million years ago that have accumulated and solidified.
● It has been in use since the Heian period.
It is used in temples, stone pagodas, and stone walls, and has become widespread throughout Japan due to its ease of processing.
● It reached its peak during the Meiji and early Shōwa periods.
・Storehouse
・Fence
・Exterior walls of a house
・Schools and Public Buildings
It was used extensively in various applications, and the town became known nationwide as **“Otani-machi = the town of stone”**.
● After the war, their numbers declined due to cost and durability concerns.
However, in recent years, its unique character and warm texture have been highly regarded,
It is once again gaining attention in areas such as store design, residential architecture, and gardening.
Advantages of Otani Stone
① Easy to work with (soft stone)
・Easy to cut out with a chisel or utility knife
・Curved surfaces and high-design finishes are also possible
→ Offers a high degree of flexibility in construction and is well-suited for shortening construction schedules
② High moisture absorption and thermal insulation properties
・It contains countless air bubbles (a pumice-like structure) and
→ Cool in summer, warm in winter
→ One of the reasons it was used as a “storehouse”
③ High fire resistance
・Since it is a volcanic rock, it does not burn
→ Highly safe as a building material
④ Unique texture (attractive appearance)
・Pale green to grayish brown
・Soft texture
・The patina that comes with age adds character
→ Popular in retail stores and upscale residences
⑤ Relatively lightweight stone
・Lighter than similar types of stone (such as granite)
→ Easy to transport and places minimal structural load
Disadvantages of Otani Stone
① It absorbs water easily, andProne to deterioration
Because it's soft and has lots of air bubbles,
・Absorbs water
・Suffer frost damage
・Prone to weathering
→ Waterproofing and regular maintenance are essential for outdoor use
② Low strength
・It has lower compressive strength than granite and andesite, for example
・Not suitable for structural use
→ Used primarily as **decorative finishes**
③ Prone to chipping during installation
Because it is a soft stone
・Chipped corners
・Prone to breaking
→ Careful construction is required
This is what Otani stone looks like.
If you're a slope contractor, why not just spray on some mortar!?
That's what you're thinking, right?
But when it comes to residential construction on private land, it can be quite a challenge to set up protective measures and find space for machinery, can't it?
If we consider the minimum necessary measures and the minimum necessary construction work,It's not mortar.That's what I think.
So that would be chemical products, such as resin-based ones, right?
Apply it to prevent deterioration.
While looking into various options, I'm trying to find a product with a proven track record in the public sector, lol.
When you think about it, products with a proven track record in the public sector are the ones that get chosen first in situations like this!
When it comes to measures for Oya Stone in the world, it’s the lies that really stand out.
The reason is that, even though the goal is to cause the natural mountain to collapse, they’re only focused on preventing the surface rocks from weathering!
This is the root of the problem.
The main purpose was supposed to be to protect against soil pressure and heavy rain, but...
It's like saying you only need to make the surface of the stone wall look nice.
As a civil engineer, I find this situation unacceptable, so I want to make sure we establish clear guidelines in this area.
I've been doing some slope stabilization work lately, but I've also been given the opportunity to work on construction projects, so it's really interesting!
And since it’s a completely different industry, I’ll need to learn everything from scratch, but it’s exciting.
It's kind of like how it's fun to try out other trades every now and then. (Although some people don't like change.)
And even though it's tiring because I have to really put my brain to work, these days the fun outweighs the fatigue lol
Let's try new things little by little, without taking any risks!
See you later.
