Details:

Creators:
Mukhopadhyay, Anal K. ; Liu, Kai-Wei
Mukhopadhyay, Anal K. ; Liu, Kai-Wei Less -
Corporate Creators:
Texas A&M Transportation Institute
Corporate Contributors:
United States. Federal Highway Administration
Subject/TRT Terms:
[+]
Aggregates
Alkali Aggregate Reactions
Alkali Silica Reactions
Concrete
Mix Design
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.


Format:
PDF
Funding:
Project 0-6656
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:830885ea2aa9d42ff48d3161f26600712d9c9ba2bcd1dd9854d8340ca52de2e7
File Type:

Supporting Files

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