Application of response surface method for optimization of stabilizer dosages in soil stabilization

The objective of this paper is to optimize the amount of dosage required for soil stabilization. The low plastic soil (LPS) is stabilized using fly ash-based geopolymer, and its performance was measured in terms of unconfined compression strength (UCS). The fly ash to activator ratio (FAR) varies from 0.6 to 2.0, and curing days (CD) (0, 14 and 28 days) are used to stabilize LPS. A mathematical equation was developed using the response surface method based on a face-centered central composite design for experimental results. Furthermore, an optimization study was carried out to find out the optimum dosage for the stabilization of LPS. The analysis is performed through analysis of variance, and it shows that the developed model gives good agreement with experimental results for all the values of FAR and CD, respectively. Based on optimization analysis, the optimized dosage for FAR is 1.5, i.e., fly ash content varies between 20 and 30% and curing days 22.75, which shows the maximum UCS value (1606.14 kPa). It is believed that the proposed optimization approach could be beneficial to the designers or engineers to have a preliminary estimation of strength before testing. The contribution of different parameters toward UCS value is presented in the form of sensitivity analysis. It was observed that curing days impart more contribution toward the higher value of UCS.