Why is the diameter of the reinforced concrete in the field often not as per the drawings?

In construction work, the diameter of the rebar listed on the structural drawings is not just a number, but the result of technical calculations to ensure the strength and safety of the building. However, in the field, situations often occur where the installed rebar diameter does not match the working drawings.

So, what exactly causes this situation?

1. Misinterpretation of Structural Drawing Specifications
Not all field workers understand the details of structural drawings. Common errors include:

• Misreading the diameter symbol (Ø)
• Assuming the size can be replaced with the nearest diameter
• Assuming small differences are insignificant

However, each rebar diameter has a different capacity and cannot be simply compared.

2. Limited Material Stock on the Field
In certain circumstances, the required rebar diameter is not available at the project site. To keep up with work progress, the diameter is changed without:

• Consultant approval
• Structural recalculation
• Documentation of changes

This practice risks compromising the quality of the building structure.

3. Inappropriate Cost-Saving Efforts
Diameter changes often occur due to cost considerations, for example, replacing larger-diameter rebar with smaller ones to reduce costs. Unfortunately, this short-term savings can lead to:

• Reduced structural bearing capacity
• Risk of cracking and deformation
• Much higher repair costs later

4. Lack of Strict Technical Supervision
Lack of supervision from:

• Field supervisor
• Site engineer
• Supervising consultant

can cause rebar diameter errors to go undetected early and only become known after the structure is covered with concrete.

5. Measurement and Identification Errors in the Field
Rebar is often identified visually without adequate measuring tools. As a result:

• Diameters appear similar but are actually different
• Errors between small sizes such as Ø10, Ø12, and Ø13 are common
• Without measuring tools such as sigmats or calipers, these errors are difficult to avoid.

6. Use of Non-Standard Reinforcement
Reinforcement that does not meet SNI standards can potentially have an actual diameter that does not match the nominal size. This can cause:

• Mismatches between drawings and materials
• Suboptimal structural performance

How to Prevent Reinforcement Diameter Mismatches
To ensure that the reinforcement diameter matches the design, the following steps must be implemented:

• Ensure all parties understand the structural drawings and technical specifications
• Use appropriate measuring tools to check the diameter
• Do not change the diameter without written approval from the designer

Choose reinforced concrete with SNI standards of guaranteed quality

Conclusion
Reinforcement diameter mismatches in the field generally occur due to a combination of technical, operational, and supervisory factors. However, reducing or changing the diameter without recalculating can seriously impact the strength of the building structure.

Choose Reinforcement According to Standards for Safe Structures
PT Intisumber Bajasakti provides reinforced concrete with SNI standards of precision and guaranteed quality, ready to support your construction project needs.

📞 Phone: 021-66675999
🌐 Website: intisumberbajasakti.com
✉️ Email: info@intisumberbajasakti.com

Contact our team now for a consultation on selecting the right rebar for your project's structural drawings.

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