Evaluation of monomer ratio on performance of GGBFS-RHA alkali-activated concretes

• Published in: Construction & building materials 2019-05, Vol.208, p.326-332
• Main Authors: Zabihi, Seyed Mahmoud, Tavakoli, Hamid Reza
• Format: Article
• Language: English
• Subjects: Alkali-activated concrete; Blast furnaces; Cements (Building materials); Concretes; Elastic modulus; Electron microscopy; Ground granulated blast-furnace slag; Measurement; Mechanical properties; Monomer ratios; Properties; Rice; Rice husk ash; Scanning microscopy; Shrinkage; Solid wastes; Strength (Materials); Ultrasonic pulse velocity; Waste management
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2019.03.026

•GGBFS-RHA based alkali-activated composites were constructed.•Different monomer ratios were evaluated.•Increasing the monomer ratio improved the durability.•Mechanical properties of AAC improved in the presence of proper monomer ratio. In his research study, alkali-activated concrete (AAC) are prepared by using ground granulated blast-furnace slag (GGBFS) as industrial material and rice husk ash (RHA) as agricultural solid waste. The mixes were constructed with 20% cement paste and 80% GGBFS-RHA alkali-activated paste, and with 100% GGBFS-RHA alkali-activated paste. Furthermore, the alkali activator dosage ratios were considered to be 2, 2.5 and 3. The compressive and elastic modulus, water absorption, ultrasonic pulse velocity (UPV) and drying shrinkage tests were performed to evaluate different characteristics of AAC. Scanning electron microscope (SEM) test was also carried out to have an insight in the microstructure of mixes. The test results showed that the mechanical properties can be improved when alkali-activated paste was used completely. The durability test results indicated that using alkali-activated paste improved the pastes by the reduction of permeability. It was also inferred from the results that the increasing the monomer ratio in alkali-activated paste resulted in a significant reduction in shrinkage values. In addition, it was found that using GGBFS-RHA pastes resulted in pore refinement in the interfacial zones. It was also reported that the interfacial transition zone (ITZ) between the cement and alkali-activated pastes became compacted by increasing the monomer ratios from 2 to 3 that water permeability can be decreased as a result.