Adopting Auto-Titration to Assess Chlorides in Concrete

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Title: Adopting Auto-Titration to Assess Chlorides in Concrete

Author(s): David Trejo and Ahmed Abdulhaq Ahmed

Publication: Materials Journal

Volume: 116

Issue: 3

Appears on pages(s): 43-52

Keywords: acid-soluble chlorides; admixed chlorides; auto-titration; manual titration; potentiometry; precipitation reaction; standardization

Date: 5/1/2019

Abstract:
Acid-soluble chloride testing, specifically ASTM C1152, is often used to estimate the chloride content in mortars and concrete containing ordinary portland cement. ASTM C1152 requires manual titration, which can be time-consuming and costly. Auto-titration can expedite testing and possibly reduce testing cost. However, some auto-titration equipment does not meet the requirements of ASTM C1152. This study first compares the results from manual titration testing meeting ASTM C1152 requirements with auto-titration testing not meeting the ASTM C1152 requirements. The study then investigates the influence of sample mass, initial water dispersant, and the pH of the test solution on acid-soluble chloride test results. Results of balanced one-way analysis of variance indicate that the test parameters and the interaction between these parameters does have a significant influence on the outcome of auto-titration test results. Recommendations for standardizing auto-titration testing for quantifying chlorides in cementitious materials are provided.