Construction Methods and Materials Flashcards

What is the primary purpose of using admixtures classified as air-entraining agents in concrete?

Answer: To improve freeze-thaw durability by creating microscopic air bubbles

Air-entraining agents create a system of tiny, uniformly distributed air voids that relieve internal pressure caused by freezing water, dramatically improving freeze-thaw resistance.

In tilt-up concrete construction, what is the purpose of the bond breaker applied to the slab-on-grade?

Answer: To prevent the wall panel from bonding to the floor so it can be tilted up

Bond breaker is a chemical coating applied to the floor slab before casting wall panels on top of it, ensuring the panels can be cleanly lifted without damaging either element.

Which foundation type is best suited for supporting a heavy structure over deep soft soils that cannot support spread footings?

Answer: Deep pile foundation

Deep pile foundations transfer structural loads down through weak upper soils to competent bearing strata at depth, either by end-bearing on rock or friction along the pile shaft.

What is the term for the minimum distance reinforcing steel must be embedded into concrete to develop its full tensile strength?

Answer: Development length

Development length is the minimum embedment required for the bond between steel and concrete to transfer the full tensile force the bar is designed to carry.

In curtain wall systems, what is the purpose of the 'pressure equalization' design principle?

Answer: To balance air pressure between inside and outside the wall to prevent water infiltration

Pressure-equalized curtain walls create a rainscreen cavity where air pressure equals the exterior, eliminating the pressure differential that drives water through joints.

What distinguishes 'stick-built' curtain wall from 'unitized' curtain wall systems?

Answer: Stick-built is assembled piece by piece on-site; unitized panels are pre-fabricated and lifted into place

Stick-built curtain walls are assembled component by component on the building face, while unitized systems arrive as complete pre-glazed factory panels that are hoisted and connected.

What is the primary function of geotextile fabric placed beneath aggregate base course in road construction?

Answer: To separate subgrade soil from base aggregate, preventing contamination and migration

Geotextile fabric acts as a separator and filter, preventing fine subgrade soils from pumping up into the aggregate base while allowing water to drain through.