Quality Control Of Concrete Construction | Quality Assurance Of Concrete

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Concrete plays a crucial role in construction, forming the backbone of structures like columns, beams, walls, and foundations. To ensure its reliability, Quality Control (QC) of concrete is imperative. This process involves checking, maintaining, and correcting the quality at various stages of construction to meet the required standards.

Quality Control Stages

Stage 1: Before Concreting

Before the actual concrete preparation, the focus is on raw materials’ quality, ensuring they meet standards. This stage involves two key steps.

Step 1: Testing Material Quality

Cement Quality: Regular tests for compressive strength are essential. Ensure no moisture exposure, periodic checks, and rejection of cement with large lumps.

Aggregates (Fine and Coarse):

  • Coarse aggregates with a rough surface are preferable.
  • Ensure hardness and strength.
  • Control water absorption, flakiness, and elongation.
  • Maintain the right ratio of 20 mm and 10 mm aggregates.

Sand Quality:

  • Passes specific sieves.
  • Low clay content (less than 8%).
  • Moisture content below 5%.

Water Quality:

  • Check for chemical harm and impurities.
  • Conduct concrete cube tests using the water sample; reject if strength is below 90%.

Step 2: Various Tests on Fresh Concrete

  • Assess the quality of the freshly mixed concrete.

Stage 2: During Concreting

Ensuring quality during the actual concreting process is vital. Several measures should be in place.

Consistent Mix Design: Align with specified mix design.
Proper Mixing: Ensure thorough mixing with 15-20 revolutions.
Segregation Prevention: Avoid ingredient separation.
Slump Tests: Conduct after every 25 m3 to verify workability.
Dropping Height Control: Limit to 1m to prevent segregation.
Vibration: Remove voids by proper post-pour vibration.
Curing: Adequate curing for 7 days after concrete hardens.

Stage 3: After Concreting

Once the concrete hardens, thorough testing and analysis are performed.

Chemical Tests: Assess concrete composition.
Core Strength Testing: Extract cores for strength evaluation.
Non-Destructive Tests: Employ methods like rebound hammer tests.
Dimension and Shape Checks: Verify structural integrity.
Clear Cover Inspection: Ensure proper concrete cover for reinforcements; reject if visible.

By adhering to these Quality Control stages, construction professionals can guarantee the durability and reliability of concrete structures.