During a concrete pour, the ready-mix truck is delayed and concrete begins to set before placement is complete. What is the most appropriate action?
Correct Answer
A) Reject the concrete and order fresh material
Once concrete has begun to set, it should be rejected and not used. Adding water or admixtures after initial set compromises the concrete's strength and durability. Fresh concrete must be ordered to ensure structural integrity.
Why This Is the Correct Answer
Once concrete has begun its initial set, the chemical hydration process has started and cannot be reversed. Using concrete that has already begun setting will result in compromised structural integrity, reduced strength, and potential failure of the concrete element. The only safe and code-compliant option is to reject the concrete and order fresh material that meets proper workability and timing requirements.
Why the Other Options Are Wrong
Option C: Vibrate the concrete more aggressively to restore plasticity
Aggressive vibration cannot restore plasticity to concrete that has begun setting. Excessive vibration of setting concrete can actually cause segregation, bleeding, and further damage to the concrete matrix. Vibration is only effective on fresh, workable concrete and cannot reverse the chemical setting process.
Option D: Add a retarding admixture to slow the setting time
Adding retarding admixtures after concrete has already begun to set is ineffective and prohibited. Retarders must be added during initial mixing to be effective. Adding admixtures to concrete that has started setting will not restore workability and may create chemical incompatibilities that further weaken the concrete.
Memory Technique
Think 'SET = REJECT' - once concrete has SET, you must REJECT it. No water, no additives, no vibration can fix concrete that has started setting.
Reference Hint
ACI 318 Building Code Requirements for Structural Concrete, Chapter 26 - Quality Control; ACI 301 Specifications for Structural Concrete, Section 4.2 - Fresh Concrete Properties
More Project Mgmt Questions
What is the minimum R-value required for wall insulation in Florida Climate Zone 2?
A subcontractor brings a new chemical product to your jobsite. Under the Globally Harmonized System (GHS), what information must be immediately available to workers?
A construction site has a trench that is 8 feet deep in Type B soil. What is the maximum allowable slope ratio for the trench walls without protective systems?
What is the maximum recommended spacing between drywall screws when attaching to wood studs?
Your crew discovers suspected asbestos-containing materials during a renovation project. What is the first action you should take?
A scaffold platform is 12 feet long and 5 feet wide. If the maximum load capacity is 25 pounds per square foot, what is the total weight capacity of this platform?
Which CSI MasterFormat Division would contain specifications for fire-stopping and firesafing materials?
In tilt-up concrete construction, what is the primary advantage of this method over conventional cast-in-place construction?
Which OSHA standard specifically addresses construction industry safety and health regulations?
A structural drawing shows a beam labeled 'W12x26'. What does the '26' represent?
People Also Study
Business & Financial Management
120 questions · 70% to pass
Contract Administration
60 questions · 70% to pass
Related Study Resources
Previous Question
A general contractor is coordinating electrical work on a multi-story building project. The electrical subcontractor will be working on energized equipment. Which OSHA standard specifically addresses lockout/tagout procedures for construction?
Next Question
During construction, you receive shop drawings for precast concrete panels that show embedded connection hardware in different locations than specified. The submittal deadline has passed and installation is scheduled to begin next week. What is the most appropriate action?