CON 353 QUESTIONS AND ANSWERS
What is the inspection prior to placing concrete? - CORRECT ANSWER✅✅Reinforcement Inspection
Reinforcement inspection - CORRECT ANSWER✅✅1. Performed by a 3rd party inspector (Residentially
performed by the building inspector) (IBC)
2. Approved placement drawings (rebar shops)
3. Rebar Diameter & Grade
4. Rebar Spacing
5. Coverage Requirements with proper support (dobies, plastic chairs, steel chairs)
6. Splices
7. American Concrete Institute - Tolerances & Placement manual produces the standards in most
specifications
Concrete Admixture? - CORRECT ANSWER✅✅Chemicals added to the concrete at time of batch or prior
to placement
Accelerators - CORRECT ANSWER✅✅•speed up the hydration, or hardening, of the wet concrete. Often
used in colder temperatures so the concrete crew has less waiting time between placing and finishing
the concrete.
Retarders - CORRECT ANSWER✅✅•slow the hydration, or hardening, of the wet concrete. Often used
in hotter temperatures so the concrete doesn't set too quickly, allowing the concrete finishing crew to
get the proper finishing work completed.
Air entraining - CORRECT ANSWER✅✅•agents add and help distribute tiny air bubbles throughout the
concrete. These tiny air bubbles help the concrete resist the freeze-thaw cycles with much less cracking
and damage.
Plasticizers and Superplasticizers - CORRECT ANSWER✅✅improve the workability of the concrete
during the wet (or plastic) stage allowing the concrete to flow more easily. They are particularly helpful
when placing concrete around congested rebar arrangements.
, What is truck spacing for concrete pours? - CORRECT ANSWER✅✅•Truck spacing is calculating the
anticipated placement rate based upon the type of element you are placing. The importance of truck
spacing stems from the specifications. Often times the specs will reference an ASTM standard. The
standard specifies discharge of the concrete shall be completed within 1 ½ hours after the introduction
of the mixing water to the cement and aggregates, or the introduction of the cement to the aggregates.
Slabs - 4" - CORRECT ANSWER✅✅•roughly 7 minute spacing
Slab 8" - CORRECT ANSWER✅✅•12 minute spacing
Wall Pours - CORRECT ANSWER✅✅•15-20 minute spacing
What does slump do? - CORRECT ANSWER✅✅•Slump test determines the concretes workability and
ability to flow in the formwork.
Typical slump? - CORRECT ANSWER✅✅•Typical slump 4"
Cylinder Compression Test? - CORRECT ANSWER✅✅•Confirms proper strength of the concrete.
28 Days - CORRECT ANSWER✅✅•Cylinder should meet specified strength
7 Days - CORRECT ANSWER✅✅•75% of strength - indicating that you know you don't have a problem.
Concrete Bucket - CORRECT ANSWER✅✅1 -3 cy crane / fork lift loaded buckets.
Concrete Pump - CORRECT ANSWER✅✅•Different size pumps dependent upon your site need.
Concrete Pump - CORRECT ANSWER✅✅1. •45, 50, 60 m radius.
2. •Minimum charge $700, $200/hour, $2.50/ yard.
What is the inspection prior to placing concrete? - CORRECT ANSWER✅✅Reinforcement Inspection
Reinforcement inspection - CORRECT ANSWER✅✅1. Performed by a 3rd party inspector (Residentially
performed by the building inspector) (IBC)
2. Approved placement drawings (rebar shops)
3. Rebar Diameter & Grade
4. Rebar Spacing
5. Coverage Requirements with proper support (dobies, plastic chairs, steel chairs)
6. Splices
7. American Concrete Institute - Tolerances & Placement manual produces the standards in most
specifications
Concrete Admixture? - CORRECT ANSWER✅✅Chemicals added to the concrete at time of batch or prior
to placement
Accelerators - CORRECT ANSWER✅✅•speed up the hydration, or hardening, of the wet concrete. Often
used in colder temperatures so the concrete crew has less waiting time between placing and finishing
the concrete.
Retarders - CORRECT ANSWER✅✅•slow the hydration, or hardening, of the wet concrete. Often used
in hotter temperatures so the concrete doesn't set too quickly, allowing the concrete finishing crew to
get the proper finishing work completed.
Air entraining - CORRECT ANSWER✅✅•agents add and help distribute tiny air bubbles throughout the
concrete. These tiny air bubbles help the concrete resist the freeze-thaw cycles with much less cracking
and damage.
Plasticizers and Superplasticizers - CORRECT ANSWER✅✅improve the workability of the concrete
during the wet (or plastic) stage allowing the concrete to flow more easily. They are particularly helpful
when placing concrete around congested rebar arrangements.
, What is truck spacing for concrete pours? - CORRECT ANSWER✅✅•Truck spacing is calculating the
anticipated placement rate based upon the type of element you are placing. The importance of truck
spacing stems from the specifications. Often times the specs will reference an ASTM standard. The
standard specifies discharge of the concrete shall be completed within 1 ½ hours after the introduction
of the mixing water to the cement and aggregates, or the introduction of the cement to the aggregates.
Slabs - 4" - CORRECT ANSWER✅✅•roughly 7 minute spacing
Slab 8" - CORRECT ANSWER✅✅•12 minute spacing
Wall Pours - CORRECT ANSWER✅✅•15-20 minute spacing
What does slump do? - CORRECT ANSWER✅✅•Slump test determines the concretes workability and
ability to flow in the formwork.
Typical slump? - CORRECT ANSWER✅✅•Typical slump 4"
Cylinder Compression Test? - CORRECT ANSWER✅✅•Confirms proper strength of the concrete.
28 Days - CORRECT ANSWER✅✅•Cylinder should meet specified strength
7 Days - CORRECT ANSWER✅✅•75% of strength - indicating that you know you don't have a problem.
Concrete Bucket - CORRECT ANSWER✅✅1 -3 cy crane / fork lift loaded buckets.
Concrete Pump - CORRECT ANSWER✅✅•Different size pumps dependent upon your site need.
Concrete Pump - CORRECT ANSWER✅✅1. •45, 50, 60 m radius.
2. •Minimum charge $700, $200/hour, $2.50/ yard.
