Comprehension quiz

Self Healing Concrete and Biomineralisation

Listen to the lesson carefully, then answer 10 comprehension questions. Pick one option per question.

Question 1What is the main idea of this lecture?

Bacteria embedded in concrete can seal cracks with limestone Epoxy injection is the cheapest way to repair roads Corals build skeletons faster than engineers expected Concrete use should be banned in marine structures

Question 2What did initially sceptical engineers question about the technology?

The strength of the healed material The cost of ordinary concrete mixes The safety of tunnel construction The longevity of the bacteria

Question 3How did researchers extend the viable lifespan of the spores?

By freezing the concrete during mixing By encapsulating the spores in clay pellets By adding more nutrients to the water By mixing the spores freely into the cement

Question 4What is concrete's rank among the most consumed substances on Earth?

First, ahead of fresh water Third, behind oil and water Second, after water Fourth, behind water, oil and steel

Question 5What does conventional concrete repair typically involve, according to the lecture?

Closing roads and injecting epoxy Replacing entire structures at high cost Spraying bacteria onto old surfaces Melting cracks with industrial lasers

Question 6What awakens the dormant bacteria embedded inside the concrete?

Vibrations from heavy traffic Direct sunlight on the surface Sudden changes in air temperature Water entering through a crack

Question 7What do the awakened microbes deposit to seal the fissure?

A layer of protective epoxy resin Limestone Calcium chloride crystals A thin film of natural rubber

Question 8How wide were the cracks healed in the early laboratory trials?

Up to several centimetres wide Up to exactly one millimetre wide Up to nearly a millimetre wide Only microscopic hairline cracks

Question 9Which natural process does the self healing mechanism mimic?

Photosynthesis in ocean algae Biomineralisation in corals Fermentation in soil bacteria Erosion of coastal limestone

Question 10Where have pilot projects already demonstrated genuine commercial promise?

In ordinary suburban housing estates In airport runways and car parks In shopping centres and sports stadiums In tunnels and marine structures