WONDER #403: Why Do Sidewalks Have Lines?

Question 1 of 3

The technical term for sidewalk lines is what?

1. contraction joints
2. concrete grooves
3. pavement depressions
4. cement cracks

Question 2 of 3

What chemical process causes cement, water, crushed rock, and sand to bond together and harden to form concrete?

1. bonding
2. hydration
3. solidification
4. gasification

Question 3 of 3

Which of the following is something builders use to place contraction joints in fresh concrete?

1. saws
2. special grooving tools
3. zip-strips
4. all of the above

Check your answers online at https://www.wonderopolis.org/wonder/why-do-sidewalks-have-lines.