How are cement and concrete related?
AnswerCement is one ingredient of concrete
Cement is the powder binder; mixed with water and aggregates it makes concrete.
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Concrete facts & stats
8 fact-checked facts about concrete, each with the reason behind it. 4 more are in today's round and join this page after it closes.
The basics
Which hand tool is used to smooth and finish a wet concrete surface?
AnswerTrowel
Finishers use flat trowels to smooth and densify the surface of fresh concrete.
Going deeper
Concrete is strong when squeezed but relatively weak under which kind of force?
AnswerTension (pulling)
Concrete handles compression well but cracks easily in tension, which is why steel reinforcement is added.
Portland cement was named for its resemblance to what?
AnswerA building stone from England's Isle of Portland
Its inventor thought the set cement looked like Portland stone, a limestone quarried on the Isle of Portland.
Concrete hardens mainly through which process?
AnswerA chemical reaction with water called hydration
Cement reacts chemically with water in hydration, forming crystals that bind the mix together.
What is keeping new concrete moist and at a suitable temperature while it gains strength called?
AnswerCuring
Curing stops fresh concrete from drying out too fast, so it keeps gaining strength over the following days and weeks.
Expert level
After how many days is concrete's standard design compressive strength usually tested?
Answer28 days
Engineers usually specify and test concrete strength at 28 days, when most strength has developed.
Ancient Romans made durable concrete using which volcanic ash?
AnswerPozzolana
Pozzolana, volcanic ash from near Pozzuoli, reacts with lime to form strong, long-lasting Roman concrete.
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