ASR testing : a new approach to aggregate classification and mix design verification : technical report.

Details

• Creators:
  Mukhopadhyay, Anal K. ; Liu, Kai-Wei
• Corporate Creators:
  Texas A&M Transportation Institute
• Corporate Contributors:
  United States. Federal Highway Administration
• Subject/TRT Terms:
  • Mix design
  • Aggregates
  • Alkali silica reactions
  • Alkali aggregate reactions
  • Concrete
  • Test procedures
  • Volumetric analysis
• Publication/ Report Number:
  FHWA/TX-14/0-6656-1
• Resource Type:
  Tech Report
• Geographical Coverage:
  Texas
• Corporate Publisher:
  Texas. Dept. of Transportation. Research and Technology Implementation Office
• Abstract:
  The main objective of this study was to develop a fast, reliable test method to determine the aggregate alkali-silica reactivity ; (ASR) with respect to the overall alkalinity of the concrete. A volumetric change measuring device (VCMD) developed at ; the Texas A&M Transportation Institute was used in this research. The VCMD simulates the aggregate–pore solution reaction in ; concrete and measures free solution volume contraction due to ASR over time. The solution volume change over time at multiple ; temperatures is modeled to determine activation energy (Ea) based on the rate theory. The VCMD-based test can reliably predict ; aggregate alkali silica reactivity in a short period of time (5 days) in terms of measuring activation energy. A representative Ea can ; be determined by testing as-received aggregates (i.e., field aggregates) with 0.5N NaOH + Ca(OH)2 solution (similar to concrete ; pore solution) and with permissible repeatability. Researchers have developed an Ea-based aggregate classification system, which ; can serve as a potential screening parameter in an aggregate quality control program. A relationship between Ea and alkalinity is ; developed, which became the basis to determine threshold alkalinity. The proposed method has the potential to be considered as an ; alternative method to the current AMBT method. ; An effective way of tailoring mix design depending on the level of protection needed is developed based on activation ; energy, threshold alkalinity, pore solution chemistry, and concrete validation testing. A new accelerated concrete cylinder test ; (ACCT) using VCMD (60°C, leaching-proof conditions) was developed to test concrete mixes in a short time. Although the testing ; period is not yet fully established, the ACCT method takes around 1 month to test a reactive straight cement concrete mix with ; varying alkali loadings (i.e., 8.9–4.5 lb/yard3) and around 3–4 months to test a slowly reactive straight cement mix with lower ; alkali loadings (e.g., 3.0–4.0 lb/yard3). The ACCT method has the ability to emerge as a potential method to test job mix.
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• Format:
  PDF
• Funding:
  Project 0-6656
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/27369/dot_27369_DS1.pdf
• File Type:
  [PDF - 57.50 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:830885ea2aa9d42ff48d3161f26600712d9c9ba2bcd1dd9854d8340ca52de2e7