The American chemist George saran taco saw ruins in the Parthenon temple, and was surprised at the durability of the stonework in 1972.
Statue thing of ancient Greece and Parthenon temple ruins endured even in 2500.
Why was the statue thing endured even in 2500 though modern concrete was deteriorated at the early stage ･･･?
He investigated an ancient natural cement.
As a result, two things turned out.

・Ancient people were using the volcanic ash and slaked lime.
・The free alkali element is almost none at all.

He removed the free alkali contained in concrete, and looked for the method of adding the element similar to the volcanic ash (natural pozzolan).

The hint was in an ancient natural science.

It will infiltrate in a short time if it paints it on concrete.
And, the material where the gap is buried with the hydrophobe inorganic substance reacting with the separation alkali element.

Material that gives concrete permanent.
It is Hydro Therm.