Glencoe: 14 Flashcards
Specialty Cements 1. 2. 3. 4.
Self-Leveling
Hydraulic
Anchor
Resurfacing
Self-leveling cement:
flows like thin syrup. Often poured over a floor to cover tubes used in radiant heat systems. Used to remodel work to level uneven subfloors.
Hydraulic Cement:
expands when mixed with water and hardens within minutes. Used to plug holes and cracks in foundations
Anchor cement:
fast setting. Used to secure railings and hardware in holes drilled in a concrete surface. Higher compressive strength than standard cement.
Resurfacing cement.
Used to repair damaged concrete surfaces. Its fine aggregate allows it to be spread in thin layers.
Aggregates:
Granular materials such as sand gravel or crushed stone.
Fine aggregate:
max diameter:
sand or other particles 1/4”
Coarse aggregate:
max diameter:
Pea gravel, crushed stone, or other suitable material larger than 1/4”.
Large aggregates in concrete should be X
solid
Should you use layer material like shale in concrete?
no
All aggregates must be X
clean because dirt and debris reduce strength of concrete
The size of aggregates:
varies depending on the kind of work
Max thickness of aggregate for finished walls:
1/5 of wall thickness
Max thickness of aggregate in slab:
1/3 of slab thickness
Never use aggregate that is larger than X the width of the narrowest space through which concrete will be required to pass during placement.
3/4
Water used to mix with concrete must be:
clean and free from oil, alkali, or acid. A good rule to follow is the water should be suitable for drinking. Sugar prevents concrete from hardening.
As more water is added to concrete mix:
the compressive and tensile strength is decreased.
Hydration:
The chemical reaction that occurs when water is added to concrete.
Concrete continues to cure as long as:
Water and unhydrated compounds exist
Dehydration:
When water is removed from substance.
Form work for casting walls is done in 1 of 2 ways:
Nuts n bolts or snap ties.
Metal rods to hold form in position then left in wall.
Repairing crack in basement wall. What is better than hydraulic cement:
Epoxy injection
Concrete still hardens when:
it hydrated or even underwater
After the reaction stage of concrete, it enters:
dormant stage which lasts several hours after which concrete begins to harden. Which is an inactive period that allows cement trucks to carry mixed concrete to job site.
Moist curing:
Improves strength of concrete. Concrete is kept moist to continue hydration.
Concrete gains most of its strength after a X day period
28 day. Concrete continues to gain strength many years afterward.
