Gemini surfactants as novel air entraining agents for concrete

The development of high performance air entraining agents for concrete is of great importance. In this work, gemini surfactants (a new class of surfactants) have been utilized as air entraining agents for the first time. Three gemini surfactants modified with different anionic groups (sulfonic, sulfate and phosphate groups) were designed and synthesized. The surface tensions and foam heights of their solutions were tested. Using them as the air entraining agents, the air contents and air-void parameters of the cement mortars were tested. The study results clearly show that the gemini surfactants have higher surface activity, foamability, foam stability and air entraining performance compared with the corresponding single-chained surfactants, and the sulfate group modified gemini surfactant has the highest performance. These surfactants are tested merely as model compounds; however, they show higher air entraining ability compared with the benchmark surfactants used in the industry, indicating great potential for practical applications.