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Concrete: making new materials
Words to learn: concrete • cement • sand • aggregate
How can a soft, wet mixture become a hard building material?
WHAT GOES INTO CONCRETE?
Concrete is made by mixing cement with water, sand and pieces of stone called aggregate.
WHAT HAPPENS?
At first the mixture is wet enough to pour. Then it gradually sets and becomes hard.
WHY IS IT USEFUL?
Concrete can be poured into shapes and then becomes strong and long-lasting, so we use it for buildings, roads and bridges.
WHAT YOU NEED TO KNOW
NOW LOOK AT THE TEXTBOOK
