Effect of rice husk ash-derived activator on the structural build-up of alkali activated materials

A Review of Recent Advances in Alkali-activated Materials from Silica-rich Wastes Derived Sodium Silicate Activators

“…The longer setting time of RHA1 SS-AAM was related to the less amorphous SiO2 content of RHA1. The use of unfiltered RHA SS also prolongs the setting time of AAM (Alnahhal et al 2021a(Alnahhal et al , 2021b. Overall, different setting time is attributed to the difference of silicate structure and quantity.…”

“…Over the past decade, the high chemical activity of RHA and the use of RHA to produce AAM have generated widespread interest among researchers (Alkhaly et al 2022;Liu et al 2022). The production of alkali silicate activator by mixing alkali and RHA (Alnahhal et al 2021a(Alnahhal et al , 2021b has greatly expanded the use of RHA as a building material.…”

“…Hydrothermal method [Fig. 2(a)] is a low-temperature synthesis method with a dissolution temperature of 20 to 120°C and a dissolution time of 5 min to 72 h (Alnahhal et al 2021a(Alnahhal et al , 2021b. Under the same conditions, raising the temperature can effectively increase the amount of dissolved SiO 2 , and 60 to 100°C is the most commonly used temperature in previous studies.…”

“…6, the most active monomeric silicates (Q 0 units) are observed in both the WGderived sodium silicate (WG SS) and RHA2-derived sodium silicate (RHA2 SS) in the 915 and 922 cm -1 bands, but the Q 1 and Q 2 units in the 978 and 992 cm -1 bands are predominant (Tchakouté et al 2016a(Tchakouté et al , 2016b(Tchakouté et al , 2016c. Commercial SS and RHA1 SS have the strongest peak at 984 cm -1 , which is dominated by Q 0 unit (Alnahhal et al 2021a(Alnahhal et al , 2021b. The difference in silicate species between RHA1 SS and RHA2 SS could be attributed to the lower solubility due to the greater quartz content in RHA2.…”

“…The final setting time of AAM, except for NaOH-AAM, takes within 1 h after the initial setting. A few workers, through experimental studies, found that the setting time of commercial SS-AAM is shorter than that of derivative SS-AAM (Luukkonen et al 2018;Samarakoon et al 2020), while others demonstrated that the setting time of derivative SS-AAM is shorter (Alnahhal et al 2021a(Alnahhal et al , 2021bTong et al 2018,). In general, the initial setting time of commercial SS-AAM is 60 to 180 min, in contrast to 40 to 100 min of derivative SS-AAM.…”