This is the 6133rd most frequent Russian word.
строительной
"Construction" or "building-related."
The word "строительной" is used as an adjective in the singular feminine form to describe the noun "техника" (equipment).
Мы купили новую строительную технику для проекта.
We bought new construction equipment for the project.
Here, "строительных" is used as an adjective in the plural feminine form to describe "материалы" (materials).
Компания специализируется на строительных материалах.
The company specializes in construction materials.
The word "строительной" is used as an adjective in the singular feminine form to describe "области" (field).