A concrete sawcut control joint is laid out at 12 feet on center across a 60-foot slab. How many joint lines are needed inside the slab, excluding the outside edges?
Correct Answer
C) 4 joint lines.
A 60-foot length at 12-foot spacing creates five spaces. Excluding the outside edges leaves cuts at 12, 24, 36, and 48 feet, so 4 interior joint lines are needed.
Why This Is the Correct Answer
A 60-foot length at 12-foot spacing creates five spaces. Excluding the outside edges leaves cuts at 12, 24, 36, and 48 feet, so 4 interior joint lines are needed.
Why the Other Options Are Wrong
Option A: 3 joint lines.
3 joint lines. is below the supported result for concrete joint layout calculation; it likely omits allowance, conversion, coverage, or final round-up.
Option B: 5 joint lines.
5 joint lines. is above the supported result for concrete joint layout calculation; it likely double-counts allowance, uses the wrong unit, or rounds too early.
Option D: 6 joint lines.
6 joint lines. is above the supported result for concrete joint layout calculation; it likely double-counts allowance, uses the wrong unit, or rounds too early.
Memory Technique
Laying Out takeoff: count the condition before counting the package.
Reference Hint
Study anchor (closed-book): memorize Concrete joint layout calculation from California Building Code, California Code of Regulations Title 24. / Title 24 California Building Code concrete joint layout concepts; know the rule or calculation trigger without relying on exam-room lookup.
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