Identification of concrete admixtures by differential thermal analysis in oxygen

✍ Scribed by N.B. Milestone

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 354 KB
• Volume: 14
• Category: Article
• ISSN: 0008-8846
• DOI: 10.1016/0008-8846(84)90106-6

✦ Synopsis

It is often desirable to identify a concrete admixture uniquely before its use to avoid adverse reactions. Methods such as ir or uv spectroscopy only broadly classify the type of admixture while chemical analysis is difficult and results are often inconclusive, especially for admixtures containing lignosulphonates. The use of DTA under 250 kPa of 02 provides a technique for identifying admixtures.

Each admixture gives an unique pattern of e~othermic peaks thus enabling its identification provided a known sample is available. Admixtures containing salts of hydroxycarboxylic acids show exotherms up to 700°C while those with free acids or sugars shown only exotherms in the range 200-400oc.