CLA Hardscape & Materials Flashcards

What is the recommended minimum thickness for a concrete pedestrian walkway slab in a residential landscape setting?

Answer: 4 inches

A 4-inch thick concrete slab is standard for residential pedestrian areas; vehicular areas typically require 6 inches or more.

Which paving pattern for rectangular brick or concrete pavers provides the greatest interlocking structural strength for vehicular areas?

Answer: Herringbone (45° or 90°)

A herringbone pattern creates maximum interlock between pavers, distributing loads laterally and resisting creep under vehicular traffic.

What material is a 'geo-grid' used for in landscape and hardscape construction?

Answer: Soil reinforcement in retaining walls and base courses

Geogrid is a polymer mesh embedded in soil or aggregate base layers to reinforce retaining walls and stabilize road or pavement base courses.

Which type of retaining wall system uses interlocking concrete blocks with no mortar and relies on mass and batter for stability?

Answer: Segmental retaining wall (SRW)

Segmental retaining walls (SRWs) use dry-stacked interlocking concrete units that rely on mass, batter (backward lean), and often geogrid reinforcement for stability.

What is 'batter' in the context of retaining wall design?

Answer: The inward lean of a wall face from vertical to improve stability

Batter is the intentional backward lean of a retaining wall face toward the retained soil, which shifts the wall's center of gravity and improves overturning resistance.

What is the function of a 'weep hole' or drainage aggregate in a retaining wall?

Answer: Relieve hydrostatic pressure by allowing water to drain through or around the wall

Without drainage relief, water pressure behind a retaining wall can cause catastrophic failure; weep holes and drainage aggregate reduce this hydrostatic pressure.