Influence of admixtures on the characteristics of aqueous foam produced using a synthetic surfactant
Authors: Shubham Raj; K. Ramamurthy; J. Murali Krishnan
Abstract: Foam characteristics, including density, stability, and texture, influence the properties of end products like foamed concrete. The present work investigates the individual and combined influence of xanthan gum and low-cost sodium-based admixtures (NaOH, NaCl, and Na2CO3) on the viscosity of sodium lauryl sulfate (SLS) foaming solution and the foam characteristics. Where xanthan gum induced its characteristic pseudo-plastic behavior to the foaming solution, the addition of sodium-based admixtures did not affect the Newtonian behavior of the SLS solution. The addition of sodium-based admixtures elevated the critical turbidity and Krafft temperature of the surfactant solution. Xanthan gum substantially reduced the liquid drainage and improved stability to a great extent. However, the increment in foam density was more gradual with increasing xanthan gum dosage, following an increase in lamella thickness. Sodium-based admixtures significantly increased the density of foam while reducing the bubble sizes. Further, the SLS solution admixed with xanthan gum and sodium-based admixture resulted in foam with properties intermediate to the foams stabilized with individual admixtures. The resulting foam had a higher density and a smaller mean bubble size than unstabilized or xanthan gum stabilized foam. In contrast, the stability was more increased compared to unstabilized or sodium-based admixture stabilized foam.
