Quantitative phase analysis of slag hydrating in an alkaline environment

• Published in: Journal of applied crystallography Vol. 53; no. 2; pp. 424 - 434
• Main Authors: Reddy, K. Chiranjeevi, Subramaniam, Kolluru V. L.
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01-04-2020; Blackwell Publishing Ltd
• Subjects: Aluminosilicates; Aluminum silicates; amorphous phases; Calcium; Decomposition; Evaluation; hydration; quantitative phase analysis; Reaction products; Slag; Sodium hydroxide; X-ray diffraction; X‐ray methods
• ISSN: 1600-5767; 0021-8898; 1600-5767
• DOI: 10.1107/S1600576720001399

An X‐ray diffraction (XRD)‐based evaluation of the crystalline and amorphous phases in slag hydrating in an alkaline environment is presented. A method is developed for the quantification of the amorphous phases present in hydrating slag in a sodium hydroxide solution. In hydrating slag, the amorphous reaction product is identified as calcium aluminosilicate hydrate. A water‐soluble sodium‐based amorphous reaction product is also produced. The XRD‐based quantification method relies on the direct decomposition of the XRD intensity pattern of the total amorphous phase present in partially hydrated slag into the intensity patterns of the amorphous unreacted slag, the hydrate and the sodium‐based product. The unreacted slag content in partially hydrated slag is also determined from the decomposition of the intensity signature of the total amorphous phase. An independent verification of the amorphous unreacted slag content in hydrating slag is obtained from measurements of blends of unhydrated and partially hydrated slag. The XRD‐based phase‐quantification procedure developed here provides a basis for evaluating the extent of reaction in hydrating slag.
A total‐intensity method for amorphous phase quantification is presented, which allows for determining the mass fractions of amorphous components in an alkali‐activated slag. The method is applied to determine the unreacted slag in an alkali‐activated slag.