Is the World Really Running Out of Sand?

What is the primary characteristic that defines sand according to the Unified Soil Classification System?

• Particles that are larger than 4.75 mm.

• Particles that are smaller than 75 µm.

• Particles that pass a 4.75 mm sieve but no more than half pass a 75 µm sieve.

• Particles that are at least 85% clay.

Which of the following is NOT a common use for sand?

• Making glass and semiconductors.

• Filtering water and creating abrasives.

• As a primary ingredient in concrete.

• Fueling rocket engines.

Why is mining sand from rivers considered particularly destructive?

• It makes the sand unsuitable for concrete.

• It causes changes in the river channel that can spread upstream and downstream.

• River sand is not a non-renewable resource.

• It is more expensive than other mining methods.

What is a benefit of using manufactured sand compared to natural sand?

• It is always cheaper to produce.

• It eliminates the need for any mining operations.

• It can reduce environmental impacts by moving operations away from sensitive areas like rivers.

• It is only used for decorative purposes.

What was the result when comparing the strength of concrete made with tumbled sand (rounded grains) versus manufactured sand (angular grains), when both had the same amount of water?

• Concrete made with tumbled sand was much stronger.

• Concrete made with manufactured sand was much stronger.

• Both types of concrete had similar strength.

• Concrete made with tumbled sand was slightly stronger.

What does "workability" refer to in the context of concrete?

• How quickly the concrete dries.

• How easily the concrete can be mixed and placed.

• The final hardness of the cured concrete.

• The amount of water needed to make the concrete.

What happens to concrete strength when more water is added to the mix than what is needed for the chemical reaction?

• The concrete becomes stronger.

• The concrete becomes weaker.

• The concrete's strength remains unchanged.

• The concrete cures faster.

When concrete mixes were prepared to have the same workability, which type of sand resulted in stronger concrete?

• Manufactured sand (angular grains).

• Tumbled sand (rounded grains).

• Both types resulted in equal strength.

• The results were inconclusive.

Why was the desert sand not suitable for concrete according to the study?

• Its particle shape was too round.

• Its particle size was too small.

• It was too expensive to transport.

• It reacted poorly with chemical admixtures.

What is one reason why sand is becoming more expensive for construction?

• There is a global shortage of sand.

• Environmental regulations for mining sand are becoming stricter.

• Sand is becoming harder to manufacture.

• The demand for concrete is decreasing.