Laitance - A layer of weak material containing cement and fines from aggregates, brought to the top of overwet concrete, the amount of which is generally increased by overworking and over-manipulating concrete at the surface by improper finishing on the concrete surface

Lean Concrete - Concrete of low cement content.

Lift - A layer of fill as spread on compacted for concrete substrate work.

Liquid Sealant - Sealant materials that install in liquid form and cool or cure concrete to their final properties; rely on long-term adhesion to the joint reservoir faces.

Limestone: Mineral rock of calcium carbonate present in concrete in many stages.

Liquid Limit - The water content at which concrete passes from a plastic to a liquid state.

Loam - A soft, easily worked soil containing sand, silt, clay and decayed vegetation. Bad foundation for concrete base construction