Case Study: Chicago River Tunnel Rehabilitation Hampered by Concrete Admixture Shortages (2021)
Project Overview
• Name: Chicago Deep Tunnel System Rehab
• Location: Chicago, Illinois
• Year: 2021
• Project Size: $530 million
• Scope: Structural rehabilitation and waterproofing of deep tunnel infrastructure
• Lead Agencies/Contractors: Chicago DOT /
Category of the Issue, Problem, or Challenge
• Supply Chain Disruption
• Chemical Admixtures for Concrete
Summary of the Issue, Problem, or Challenge
The project encountered delays when key chemical admixtures (water reducers and corrosion inhibitors) were backordered due to global supply constraints in specialty chemicals.
Root Cause Analysis
- Global shortages in petrochemical raw materials needed for admixture production.
- Increased demand from concurrent construction and industrial sectors.
- Limited number of admixture manufacturers qualified for high-spec tunnel concrete.
- Lack of alternate admixture suppliers and contingency procurement plans.
Impacts Due to the Issue, Problem, or Challenge
• 2.5-month delay in concrete placement and curing schedules.
• Additional costs for expedited shipments and admixture substitutions (~$2.4 million).
• Risk of compromised concrete performance and project quality control.
Corrective Actions Taken
- Identified and qualified alternative admixture suppliers.
- Modified mix designs to reduce reliance on scarce admixtures.
- Established advanced procurement and supply monitoring systems.
Lessons Learned
- Specialty chemical supply chains can pose significant project risks.
- Flexibility in material specifications helps mitigate supply disruptions.
- Early qualification of multiple suppliers reduces schedule impacts.
Audit & Prevention: Project Control Questions to Ask on Future Projects to Help Control the Situation
- Are admixture suppliers diversified and pre-qualified?
- Is procurement timing sufficient for specialty materials?
- Are mix designs adaptable to changes in admixture availability?