A Laboratory Assessment of Different Molarity of Alkaline Activator Geopolymer Concrete by Replacement of Fly Ash by Rice Husk Ash

Various molar concentrations of sodium hydroxide and sodium silicate solutions were prepared, ranging from 11M to 14M, and were utilized to activate the geopolymerization process. For each molarity, a series of mixes was designed with incremental RHA replacements of 5%, 10%, 15%, and 20%. On the 28th day, the compressive strength of the concrete mixes find the optimum value of 12M, 900Ccuring temperature and 10% replacement of rice husk provide the best result as per the design of M-30 grade of geopolymer concrete.Laboratory assessments revealed several key findings. Firstly, as RHA content increased, a noticeable improvement in the early strength of GC was observed, attributed to the high reactivity of the silica in RHA. However, beyond 10% RHA replacement, diminished returns in strength properties were noted. Secondly, the molarity of the alkaline activator played a significant role in the setting time and workability of the GC, with higher molarities causing rapid setting but reduced workability.