Plywood – behavior, sizes, and directional properties Which statements about commercial plywood are generally correct in construction practice?
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APlywood does not split or crack easily with normal atmospheric changes
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BCommercial panels are available up to about 150 cm in width and 300 cm in length
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CDue to cross-lamination, tensile strength is comparatively uniform in all directions of the plane
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DPlywood sheets are light in weight relative to solid timber of equivalent thickness
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EAll of the above
Answer
Correct Answer: All of the above
Explanation
Introduction:Plywood is a widely used engineered wood product. Alternating veneer directions give it stability and relatively uniform in-plane properties, making it reliable for formwork, sheathing, furniture, doors, and partitions. The item checks multiple true characteristics commonly cited in civil engineering texts.
Given Data / Assumptions:
- “Commercial plywood” refers to general building grades, not specialized structural plywood.
- Typical maximum panel sizes in the market are being referenced.
Concept / Approach:
Cross-lamination reduces anisotropy and minimizes splitting along grain. It also moderates dimensional changes due to moisture fluctuations. Market availability often includes large panels, reducing joints and speeding installation.
Step-by-Step Solution:
1) Splitting/cracking: Cross plies resist propagation of checks caused by humidity and temperature changes.2) Sizes: Large panels, commonly around 1.2–1.5 m wide by 2.4–3.0 m long, are widely available, matching the statement.3) Directional strength: Cross-grain stacking yields relatively uniform in-plane tensile behavior compared with solid wood.4) Weight: Lower density species and thinner veneers make plywood comparatively light for its stiffness and size.Verification / Alternative check:
Common product data sheets corroborate the general size ranges and the cross-laminated behavior that resists splits and warping.
Why Other Options Are Wrong:
Each individual statement is broadly correct for commercial plywood; thus “All of the above” is the correct combined choice.
Common Pitfalls:
Assuming plywood is completely isotropic; it is only more uniform than solid timber. Ignoring panel orientation during installation can still lead to performance differences.
Final Answer:
All of the above