CMA Construction Materials & Methods 3 — Questions and Answers
Question 1: What distinguishes Type X gypsum wallboard from standard Type W (regular) wallboard?
- Greater thickness only
- Addition of glass fibers and other non-combustible aggregates for enhanced fire resistance (Correct answer)
- Higher moisture resistance due to silicone additives
- Use of synthetic gypsum instead of natural gypsum
Correct answer: Addition of glass fibers and other non-combustible aggregates for enhanced fire resistance
Type X wallboard contains glass fibers and special aggregates in the gypsum core that slow calcination and maintain integrity under fire exposure longer than regular board.
Question 2: In steel frame construction, what is the function of a 'shear tab' (single-plate shear connection)?
- Transfers axial tension between beam and column
- Transfers vertical shear while allowing beam-end rotation (Correct answer)
- Provides full moment resistance at the beam-column joint
- Connects diagonal bracing to beam flanges
Correct answer: Transfers vertical shear while allowing beam-end rotation
A shear tab is a simple framing connection that transfers vertical shear load while allowing the beam end to rotate freely, making it a 'pinned' connection.
Question 3: What is 'tilt-up' concrete construction?
- Precast panels manufactured off-site and transported to the project
- Concrete wall panels cast horizontally on the slab and then tilted into vertical position (Correct answer)
- Thin concrete shells formed over inflated fabric molds
- Post-tensioned slabs lifted by hydraulic jacks
Correct answer: Concrete wall panels cast horizontally on the slab and then tilted into vertical position
Tilt-up construction involves casting large concrete panels flat on the floor slab and then tilting them upright with a crane to form the building walls.
Question 4: Which fastener is specifically designed to connect wood ledgers to concrete or masonry walls in seismic zones?
- Standard hex-head lag bolt
- Adhesive anchor (chemical anchor)
- Code-listed ledger connector with shear and tension values (Correct answer)
- Toggle bolt with sleeve expansion
Correct answer: Code-listed ledger connector with shear and tension values
In seismic zones, IBC and AWC require tested, listed ledger connectors with published shear and withdrawal values; standard lag bolts lack the required testing documentation.
Question 5: What is the water-cement (w/c) ratio's primary effect on hardened concrete?
- Higher w/c ratios increase compressive strength
- Lower w/c ratios increase compressive strength and reduce permeability (Correct answer)
- The w/c ratio affects color but not structural properties
- Higher w/c ratios reduce shrinkage cracking
Correct answer: Lower w/c ratios increase compressive strength and reduce permeability
Reducing the water-cement ratio produces a denser cement paste with higher compressive strength, lower permeability, and improved durability.
Question 6: Which of the following best describes cross-laminated timber (CLT)?
- Solid-sawn lumber graded for tension applications
- Engineered panels with alternating perpendicular laminations glued together (Correct answer)
- Plywood panels exceeding 1.5 inches in thickness
- Strand-based composite panels used for subfloor applications
Correct answer: Engineered panels with alternating perpendicular laminations glued together
CLT panels consist of multiple layers of lumber laminations oriented at 90° to adjacent layers and glued together, providing two-way structural capacity similar to concrete slabs.
Question 7: In curtain wall construction, what is a 'pressure-equalized' rain screen design intended to accomplish?
- Equalize the temperature between interior and exterior glazing panes
- Neutralize the pressure difference across the outer cladding to stop water infiltration (Correct answer)
- Balance structural loads between adjacent curtain wall panels
- Match the air pressure in the cavity to the building interior
Correct answer: Neutralize the pressure difference across the outer cladding to stop water infiltration
Pressure-equalized rain screen design vents the cavity behind cladding to equalize air pressure, eliminating the driving force that pushes rainwater through joints.
CMA Construction Materials & Methods 3
What distinguishes Type X gypsum wallboard from standard Type W (regular) wallboard?