Discovery about building on clay soil

Greetings to the beloved people of hive.
Today I want to share my discovery with this great community. This morning as I went to building site to look around and check if my building is still intact, because my building is just on dpc level. I have been hearing the story of building been infected by clay soil, I never new that it was true, I was thinking that is just a falarcy so I didn't take it as a true talk.
While in my building site I saw a mark that look as if it was broken by someone and I know that no one would think of breaking that part, so I asked a question about what I saw I was told that my building has been infected by the soil.

It was a surveyor that was telling me this, I asked him how can a building be infected by a soil, he told me that it's clay soil, he said that before any building site will stand on a land that has clay soil that the land must be treated, hearing this made me more confused.
Nevertheless, I asked the surveyor the solution to this because he said that if the land is treated that it may likely collapse the building.

Treatment to give to any clay soil land before building.

After digging the foundation, you have to get a Sharp solid soil and pour it round the foundation. Then buy a water proof nylon and spread on top of the sharp solid soil.
Then put about 3 inches of mixed concrete on top before dropping the iron basket and of course mount the pillars.
After mounting the pillars, you then pour up to 2 to 3 feet of mixed concrete to bury the iron which is the basement basket and the pillars.

Now this process is very costly but is preventive because when you go through this process when the clay wants to react, the sharp sand will subdue it because clay and sharp sand are enemy.