More examples

• The bomb shelter has concrete walls that are three metres thick.
• The foundation of the house is built from rubble overlaid with concrete.
• A row of reinforced concrete pillars supports the bridge.
• Weeds were pushing up through the cracks in the concrete.
• Don't walk on the concrete until it has set.

More examples

• It is sometimes easier to illustrate an abstract concept by analogy with something concrete.
• He drew attention to the absence of concrete evidence against the defendant.
• I have a suspicion that he's having an affair, though I don't have any concrete proof.