COSC 253 EXAM 2 HARTELL | QUESTIONS AND
ANSWERS | WITH COMPLETE SOLUTION
How is concrete priced and ordered? Answer - - Concrete is typically measured
and ordered by the cubic yard
- Typical transit-mix truck can mix and deliver up to 10 cubic yards
- Wet(fresh) concrete weighs approximately 150 lbs per cubic foot or 4,050 lbs
per cubic yard
Construction steps of concrete construction Answer - 1. Mixture design to
meet specification
2. Batching of ingredients and mixing of concrete
3. Handling and placement of concrete
4. Consolidation procedures
5. Finishing procedures
6. Curing of concrete
Normal strength concrete Answer - - 2500 to 6000 psi compressive
strength
- Made with conventional ingredients
High strength concrete Answer - - Greater than 6,000 psi to roughly 20,000 psi
- Admixtures and supplementary cementitious materials are required to reach
higher strengths
, Batching of ingredients and mixing of concrete Answer - - Most concrete is
prepared at batch plants and delivered to the construction site in the transit-
mix trucks
- The mixing trucks are constantly rotating so that the concrete is ready to be
placed when arriving on site
- Smaller batches may be prepared on site by hand or with power mixers
Placing concrete Answer - - Avoid delays - place ASAP
- Depending on the conditions, concrete can be - placed up to 90 minutes after
- Mixing commences (can't place after 90 minutes)
- May be placed directly from truck
- Pump truck
Aggregate Segregation Answer - - Separation of large aggregate from the finer
portions of concrete mix - must be avoided
- Solution - Place concrete as close to the final position as possible
Consolidation Procedures Answer - - Compaction eliminates voids and air
pockets within the concrete
1. Hand rodding or tramping
2. Screeding (top)
3. Vibration (bottom)
Finishing Procedures Answer - - Finishing is required for exposed surfaces
- Various surface textures can be specified to add surface traction/friction or for
architectural conditions
- Expansion/construction joints are made to minimize cracking
ANSWERS | WITH COMPLETE SOLUTION
How is concrete priced and ordered? Answer - - Concrete is typically measured
and ordered by the cubic yard
- Typical transit-mix truck can mix and deliver up to 10 cubic yards
- Wet(fresh) concrete weighs approximately 150 lbs per cubic foot or 4,050 lbs
per cubic yard
Construction steps of concrete construction Answer - 1. Mixture design to
meet specification
2. Batching of ingredients and mixing of concrete
3. Handling and placement of concrete
4. Consolidation procedures
5. Finishing procedures
6. Curing of concrete
Normal strength concrete Answer - - 2500 to 6000 psi compressive
strength
- Made with conventional ingredients
High strength concrete Answer - - Greater than 6,000 psi to roughly 20,000 psi
- Admixtures and supplementary cementitious materials are required to reach
higher strengths
, Batching of ingredients and mixing of concrete Answer - - Most concrete is
prepared at batch plants and delivered to the construction site in the transit-
mix trucks
- The mixing trucks are constantly rotating so that the concrete is ready to be
placed when arriving on site
- Smaller batches may be prepared on site by hand or with power mixers
Placing concrete Answer - - Avoid delays - place ASAP
- Depending on the conditions, concrete can be - placed up to 90 minutes after
- Mixing commences (can't place after 90 minutes)
- May be placed directly from truck
- Pump truck
Aggregate Segregation Answer - - Separation of large aggregate from the finer
portions of concrete mix - must be avoided
- Solution - Place concrete as close to the final position as possible
Consolidation Procedures Answer - - Compaction eliminates voids and air
pockets within the concrete
1. Hand rodding or tramping
2. Screeding (top)
3. Vibration (bottom)
Finishing Procedures Answer - - Finishing is required for exposed surfaces
- Various surface textures can be specified to add surface traction/friction or for
architectural conditions
- Expansion/construction joints are made to minimize cracking
