CLA CLA Hardscape & Materials 2

Question 1

What does 'compressive strength' measured in PSI indicate for a hardscape material like concrete?

Accepted Answer

The force per unit area the material can withstand under compression before failure

Answer

Compressive strength (PSI) is the maximum compressive load per square inch a material can sustain; concrete for walkways is typically specified at 3,000–4,000 PSI.

Question 2

Which surface treatment for concrete improves slip resistance for pedestrian areas?

Accepted Answer

Exposed aggregate or broom finish

Answer

Broom finishing or exposed aggregate creates surface texture that increases friction coefficients and reduces slip hazard, especially when wet.

Question 3

What is the purpose of 'control joints' (contraction joints) in a concrete slab?

Accepted Answer

Create weakened planes that guide crack formation to controlled locations

Answer

Control joints are saw-cut or tooled grooves that create planes of weakness, directing inevitable shrinkage cracks to predictable, aesthetically acceptable locations.

Question 4

What is the typical recommended base depth for a permeable interlocking concrete pavement (PICP) system designed for stormwater infiltration?

Accepted Answer

6–12+ inches of open-graded aggregate

Answer

PICP requires a deep open-graded aggregate reservoir (often 6–18 inches) to store and infiltrate stormwater, unlike traditional pavements that simply convey runoff.

Question 5

What is 'efflorescence' in masonry and concrete hardscape materials?

Accepted Answer

White salt deposits that leach to the surface as water migrates through the material

Answer

Efflorescence is the migration of soluble salts to a masonry or concrete surface where they crystallize as white deposits when water evaporates.

(CLA) Certified Landscape Architect Practice Test

(CLA) Certified Landscape Architect Practice Test

CLA CLA Hardscape & Materials 2