What do they use to stick bricks together?

Answer 1

Mortar is used to stick bricks together. It can be either:

* cement mortar: a mixture of water, sand and cement, or * lime mortar: a mixture of lime, sand and water.(This is not used often for modern construction because of its porosity) * clay mud mortar: a mixture of clay sand, water (only used in some adobe construction)

Lime is sometimes added to cement mortar to improve workability, waterproof qualities, and reduce shrinkage. Straw is sometimes added to clay mortar to reduce shrinkage.