Applying compound principle to optimizing the efficacy of air entraining agent based on sodium dodecyl benzene sulfonate

Abstract

To optimize the efficacy of sodium dodecyl benzene sulfonate (SDBS), a compound technology was employed by adding fluorocarbon surfactant (FC) and changing its mole fraction. A series of compound air entraining agents (CAEAs) were prepared by adjusting the ratio of FC and SDBS, and characterized in terms of foamability, foam stability and surface tension, while the molecular interaction was calculated. The results showed that FS3, with the mole fraction of FC being 0.3 in CAEAs, had the highest foamability and greater foam stability because there was a positive molecular interaction in FS3. Thus, concrete with FS3 (FS3/C) was prepared, and its performance and pore characterization was measured and analyzed. Concrete with SDBS (SDBS/C) was served as the control. The findings demonstrated that FS3/C possessed a 0.5 % increase in air content, a 31.9 % reduction in air content loss over time, a 9.4 % increase in slump, and a comparable compressive strength loss relative to SDBS/C. More notably, SDBS/C was destroyed after 50 freeze-thaw cycles, whereas FS3/C showed only a 2.54 % mass loss and a relative dynamic elastic modulus as high as 88.9 % after 300 freeze-thaw cycles. The better frost resistance was attributed to the smaller pore diameter reduced by 12.1 % and the smaller pore spacing factor (L) reduced by 12.7 %. Therefore, it could be concluded that employing compound technology to optimize the air entraining agent based on SDBS by adjusting the FC-to-SDBS ratio was effective.