This is the 10057th most frequent Polish word.
betonu
"Betonu" means "concrete" in English.
In this sentence, 'betonu' refers to the material concrete used in construction.
Budynki w centrum miasta są zbudowane głównie z betonu.
The buildings in the city center are primarily made of concrete.
Here, 'betonu' indicates the material composition of the wall.
Nie mogłem wywiercić otworu, bo ściana była z betonu.
I couldn't drill a hole because the wall was made of concrete.
This usage of 'betonu' emphasizes its material predominance in the replacement structure.