Title:
Improving Sulfate Resistance in Alkali-Activated Self-Compacted Concrete: Utilizing Precursor Combinations and Dry-Powder Activators as a Novel Approach for Enhanced Durability
Author(s):
Dima Kanaan
Publication:
Symposium Paper
Volume:
362
Issue:
Appears on pages(s):
127-146
Keywords:
alkali-activated SCC; durability; eco-concrete; silicate/carbonate; sulfate attack; ternary blend
DOI:
10.14359/51740879
Date:
6/5/2024
Abstract:
This study investigates the synthesis of alkali-activated self-compacted concrete (AASCC) mixtures, in which slag is replaced by fly ash (FA) and silica fume (SF), in various combinations including single, binary, and ternary precursors activated with a 1:1 ratio of sodium metasilicate and sodium carbonate. The impact of activator dosage and precursor combinations on the fresh and hardened properties as well as durability was evaluated. The AASCC combinations were subjected to rigorous sulfate attack scenarios and wetting-drying cycles. The efficient development of AASCC depends critically on the precise selection of precursor materials, proportions, activator type, and dosage, with larger fractions of sodium carbonate/silicate activators resulting in delayed reaction kinetics.
Slag replacement with various SF or FA class-F ratios modulated the particle size distribution of the total binder material, leading to enhancements in the characteristics of AASCC mixtures. The highest compressive strength and ultrasonic pulse velocity values were achieved at a 25% activator dosage. The emergence of diverse reaction products and binding gels, including C-(N)A-S-H, significantly influenced transport mechanisms such as capillary sorptivity, permeable pores, and bulk electrical resistivity. AASCC mixtures demonstrated resistance to sulfate attack for up to six months, indicating their potential for sustainable construction practices in sulfate-rich environments. This study provides valuable insights into the development of AASCC mixtures, paving the way for the wider use of sustainable construction materials.