Influence of Na2O Content and Ms (SiO2/Na2O) of Alkaline Activator on Workability and Setting of Alkali-Activated Slag Paste

Abstract

The performance of alkali-activated slag (AAS) paste using activators of strong alkali components is affected by the type, composition, and dosage of the alkaline activators. Promoting the reaction of ground granulated blast furnace slag (GGBFS) by alkaline activators can produce high-strength AAS concrete, but the workability might be drastically reduced. This study is aimed to experimentally investigate the heat release, workability, and setting time of AAS pastes and the compressive strength of AAS mortars considering the Na2O content and the ratio of Na2O to SiO2 (Ms) of binary alkaline activators blended with sodium hydroxide and sodium silicate. The test results indicated that the AAS mortars exhibited a high strength of 25 MPa at 24 h, even at ambient temperature, even though the pastes with an Na2O content of ≥6% and an Ms of ≥1.0 exhibited an abrupt decrease in flowability and rapid setting.

Influence of SiO2, Al2O3, CaO, and Na2O on the elevated temperature performance of alkali‐activated treated palm oil fuel ash‐based mortar

“…Subsequently, the mixing process was continued at medium speed for 1 min 9 . The setting time observation in the mixtures with varying N 2 O concentrations was similar to the results observed by previous researchers 38,39 . With varying silica modulus, the setting time increased with reducing N 2 O concentration.…”

A Study on Initial Setting and Modulus of Elasticity of AAM Mortar Mixed with CSA Expansive Additive Using Ultrasonic Pulse Velocity

“…The setting of AAM mortar is affected by the conditions of the alkali activator, and it is generally faster than that of ordinary Portland cement (OPC) [ 56 , 57 ]. Table 3 shows the setting time of the AAM mortar according to the content of EA.…”

Importance of Cation Species during Sulfate Resistance Tests for Alkali-Activated FA/GGBFS Blended Mortars

“…The activator concentration was 8% Na 2 O with an Ms of 1.4 in the FA-based geopolymer and 4% Na 2 O with an Ms of 1.0, 1.5, and 2.0 in the GGBFS blended mortars. It should be noted that the Na 2 O content and Ms value of the alkaline activators are crucial factors in the property development of the alkali-activated materials [48]. For each case, GGBFS was replaced with 30 wt.% and 50 wt.% of the FA amount, respectively.…”