Learn French: Le béton, c'est rugueux et dur.

Both are grammatically correct, but they have a subtle difference in meaning. Using c'est after the noun highlights that you are making a broad generalization about the material as a whole. Le béton est rugueux could sound like you are describing a specific piece or batch of concrete in front of you, whereas Le béton, c'est rugueux expresses a universal fact: Concrete, in general, is rough.

If we changed the subject to a feminine plural noun like Les briques (bricks), would the adjectives become rugueuses and dures?

No, they wouldn't change at all! When you use c'est to make a general statement, the adjective that follows is always masculine singular, acting as a neutral form. Even if the topic is feminine or plural, the adjectives remain invariable. So you would say: Les briques, c'est rugueux et dur.

Why do we need Le before béton? In English, we just say Concrete without an article.

In French, you must use the definite article (le, la, l', les) when talking about a noun in a general sense. This includes concepts, categories, and materials. English drops the article for generalities, but French requires it to show you mean all concrete everywhere.

Why is there a comma separating Le béton from the rest of the sentence?