Cost of Service Life Optimization Part 2: de Sitter’s ‘Law of Fives’

Our own Innovation Engineer, Nick Heim, P.E., was featured in the Engineering Management Institute. This is part two of the series.

The blog post emphasizes the importance of periodic inspection and service life optimization to enhance public safety and reduce future costs. It revisits de Sitter’s "Law of Fives," which outlines four phases in the lifecycle of concrete structures, and provides practical examples of how this theory applies to parking structures.

Key Highlights in the Article:

Periodic Inspection for Public Safety:

• Regular inspections identify issues in structures that may deteriorate due to environmental factors.
• Addressing these issues often requires significant funding.

Service Life Optimization:

• Asset owners seek ways to reduce future costs after reviewing inspection results.
• Service life optimization is presented as a solution.

de Sitter’s ‘Law of Fives’:

• The theory proposes four phases in the lifecycle of concrete structures:
  • Good Practice (Phase A): Initial design, construction, and quality control.
  • Maintenance (Phase B): Periodic inspection and general maintenance practices.
  • Repair and Maintenance (Phase C): Isolated concrete removal and replacement.
  • Renovation (Phase D): Widespread concrete removal and replacement.
• Financial implication: “One dollar spent in Phase A equals $5 in Phase B equals $25 in Phase C equals $125 in Phase D.”

Practical Examples of the Law of Fives:

• Focus on parking structures as the subject asset.
• Emphasis on phases B, C, and D.

Maintenance (Phase B):

• Periodic Inspection: Aims to catch issues early and create a remediation plan before they escalate.
  • Inspection frequency can vary but should not exceed five years.
• General Maintenance Practices: Involves repair and replacement of nonstructural elements to protect the underlying structure.
  • Examples: Cleaning, waterproofing, snow removal best practices, chloride washdowns, and flushing of drains.

Repair and Maintenance (Phase C):

• Isolated concrete removal and replacement due to issues or inaction in phases A and B.
• The structure is generally salvageable, and repair costs are not approaching the replacement cost for the entire structure.

Renovation (Phase D):

• Widespread concrete removal and replacement due to issues or inaction in phases A-C.
• The cost to repair the structure is approaching the cost to replace it entirely.

Service Life Optimization Examples:

• Failed Joint Sealant: Inaction can lead to deterioration from category B (replacement of joint sealant) to categories C and D (deterioration of precast concrete and structural connections).
• Concrete Deterioration: Inaction and subsequent corrosion of steel accelerate deterioration, increasing the cost to remedy isolated conditions.

Read the full article to dive deeper into each of these topics.