Evaluation of Chloride Limits for Reinforced Concrete Phase A

The current American Concrete Institute (ACI) 318 Building Code chloride limits are based on research in the 1980s with primarily portland cement mixtures. These are conservative limits to ensure that the available chlorides in concrete will not exceed the threshold chloride concentration that can initiate corrosion. ACI 222R recommends more conservative chloride limits than those in ACI 318. There is no clear agreement on the actual chloride threshold concentration that initiates corrosion and there is additional uncertainty for mixtures that contain supplementary cementitious materials (SCMs). In general, the threshold concentration is assumed to be between 2 to 4 lbs per cubic yard (0.05 to 0.1% by mass of concrete). It is useful to evaluate whether the ACI 318 Building Code chloride limits are appropriate for the different exposure classes of Exposure Category C and for different concrete mixtures that contain SCMs. This project was conceptualized to be performed in two phases. The objective of Phase A is to establish a relationship between total chlorides calculated from the concrete materials and water-soluble chlorides measured on concrete specimens at a test age between 28 and 42 days. This information is useful by itself for concrete producers to use and is necessary information for mixtures that will be evaluated in Phase B, which has the following objectives: (1) Propose chloride limits on the basis of total cementitious materials and (2) Evaluate the validity of current chloride limits for reinforced concrete stated in ACI 318. This report summarizes the findings of Phase A.

• Record URL:
  https://www.nrmca.org/research_engineering/Documents/ChlorideLimitsReport.pdf
• 
• Corporate Authors:

  National Ready Mixed Concrete Association

  900 Spring Street
  Silver Spring, MD  United States  20910
• Authors:
  • Obla, Karthik
  • Lobo, Colin
  • Hong, Rongjin
  • Berke, Neal
• Publication Date: 2017-7

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 28p

Subject/Index Terms

• TRT Terms: Chloride content; Reinforced concrete
• Identifier Terms: ACI 222R; ACI 318; American Concrete Institute Building Code
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 01648490
• Record Type: Publication
• Files: TRIS
• Created Date: Oct 16 2017 12:17PM