Rheology of Alkali-Activated Blended Binder Mixtures

Abstract

Alkali-activated cement (AAC) is an alternative cement that has been increasingly studied over the past decades mainly because of its environmental benefits. However, most studies are on heat-cured AACs and are focused on mechanical properties. There is a lack of research on the fresh properties of ambient-cured AAC systems. This study investigates the rheological properties of ambient-temperature-cured alkali-activated blended binder mixtures activated with sodium silicate and sodium hydroxide solutions. The influence of binder amount, alkaline solid to binder ratio (AS/B), sodium silicate to sodium hydroxide solids ratio (SS/SH), and total water content to total solid (from the binding materials) ratio (TW/TS) on the rheological properties are investigated. The effect of borax as an admixture and silica fume as a replacement for fly ash is also investigated. The results showed that both the yield stress and plastic viscosity are mainly affected by the binder content and TW/TS ratio decreasing with the increase of each parameter. The yield stress increased with the increase of the SS/SH ratio. Borax significantly reduced the yield stress, while silica fume’s effect was dependent on its dosage.

Alkali activated cement mixture at ambient curing: Strength, workability, and setting time

“…This is due to the formation of primary calcium silicate hydrate (C-S-H) gel in the early stages of the reaction due to the bonding of the Ca 2+ ions from the slag to the silicate ions in the sodium silicate. 25 25 reported a similar result. Like compressive strength, the TW/TB ratio, with 59% contribution, is the most significant factor for workability.…”

“…All the investigated parameters increased workability. Tekle et al 25 reported a similar result. Like compressive strength, the TW/TB ratio, with 59% contribution, is the most significant factor for workability.…”

“…Palacios et al 46 and Puertas et al 47 reported that AAC activated with sodium silicate has a lower setting time than those with sodium hydroxide. This is due to the formation of primary calcium silicate hydrate (C‐S‐H) gel in the early stages of the reaction due to the bonding of the Ca 2+ ions from the slag to the silicate ions in the sodium silicate 25 …”

Physicomechanical Behavior of High-Performance Concrete Reinforced with Recycled Steel Fibers from Twisted Cables in the Brittle State—Experimentation and Statistics

“…This adjustment is crucial to maintain the desired strength of the concrete while simultaneously achieving the desired level of workability [74][75][76]. A higher volume of binder in concrete mixtures decreases particle interactions and friction, leading to an increase in plastic viscosity, ultimately resulting in increasing flowability [77][78][79]. The results also indicate that the increase in L/d has a less significant effect on the slump, regardless of the variations in W/B and SFC values.…”