Construction Materials and Methods
What to know
Construction Materials and Methods tests how landscape elements are built: soils and aggregates, concrete, asphalt, unit paving, wood, metals, retaining walls, drainage structures, irrigation, and planting. Know material properties, typical assemblies, jointing, base preparation, compaction, and compatibility. Understand how specifications describe materials and how details show connections, transitions, and tolerances.
Traps
Questions often show a plausible detail with the wrong substrate or a missing joint. Concrete needs adequate base, reinforcement where required, control joints, and curing; asphalt needs a compacted aggregate base and proper compaction. Wood in contact with soil needs decay-resistant species or separation. Dissimilar metals can corrode. Unit pavers need edge restraint and a setting bed. Watch minimum versus typical dimensions and whether a detail is designed for pedestrian or vehicular loading.
Worked example
Order concrete for a 4 in thick, 10 ft by 20 ft walk. Area = 200 sf. At 4 in, one cubic yard covers 81 sf, so 200/81 = 2.47 cy; order about 2.5 cy plus waste. A 4 in compacted aggregate base needs 200 x 4/12 = 66.7 cf, or 2.47 cy. Control joints are commonly spaced about 24 to 36 times slab thickness: a 4 in slab gets joints roughly every 8 to 12 ft.
Rule of thumb: pedestrian concrete is often 4 in on 4 in base; vehicular concrete is often 6 in on 6 in base, subject to design.