concrete Flashcards
(22 cards)
What are the two main types of concrete systems?
Site-cast and precast concrete.
Why is concrete valued in fire-sensitive buildings?
Concrete is non-combustible and has excellent fire resistance.
What is a major disadvantage of site-cast concrete?
It requires formwork, which means you build the structure twice.
What challenge does solid concrete present for utilities?
It’s difficult to insert plumbing/electrical without extensive pre-coordination.
Why does site-cast concrete require expert labor?
Because critical rebar placement and finishing is hidden inside formwork.
How does transportation impact concrete selection?
Precast must be transported in large pieces; site-cast requires timely delivery of mix.
What defines a flat plate system?
A slab supported directly by columns without capitals or drop panels.
What defines a flat slab system?
A slab with added column capitals or drop panels to reduce punching shear and deflection.
When is a flat slab preferable over a flat plate?
In heavy load areas like industrial floors or unknown future use.
What is a waffle slab?
A two-way ribbed slab system using reusable pans, designed to be seen and span longer distances.
When is a waffle slab used?
In architecturally expressive, fire-rated, load-bearing spaces like school cafeterias.
What is a joist slab?
A one-way concrete slab with long pans for rebar, typically for heavier loading than flat slabs.
What distinguishes joist slabs from waffle slabs structurally?
Joist slabs are one-way; waffle slabs are two-way.
What is a major benefit of precast concrete?
Fabrication in controlled environments ensures high quality and fast site installation.
What is a flexicore slab?
A precast concrete slab with hollow cores to reduce weight and allow limited conduit routing.
What are some planning limitations of precast systems?
They have fixed modules and limited flexibility for on-site changes.
Why does local economy affect concrete system choice?
Cities may be oriented toward steel or concrete, affecting labor cost and availability.
What is one structural benefit of concrete?
It creates a monolithic system with integrated columns and slabs.
What influences the aesthetic of site-cast concrete?
The material of the formwork (e.g., plywood, steel, fiberglass).
What’s a benefit of concrete topping in precast systems?
Provides a smooth, level surface and ties elements together structurally.
When is precast concrete ideal?
In repetitive, low-flexibility projects like hotels or dorms where fire safety and speed are critical.
What curing timeline affects site-cast concrete progress?
7 days for handling, 28 days to reach full strength.
