Comparative Study of Cement Foam Agents

Ordinary Portland cement P.O 42.5 was provided by Anhui Conch Cement Co., Ltd. (Wuhu, China). The basic properties of cement are listed in Table 1. Calcite (Cal) and muscovite (Mus) used in the study were obtained from Shanlinshiyu Mineral Products Co., Ltd. (Guzhang, China). The particle size distributions of the raw materials are shown in Figure 1. X-ray diffraction (XRD) patterns and SEM images of calcite and muscovite are shown in Figure 2.
Two representative surfactants with alkyl tails of the same length were used as foaming agents and provided by Shanghai Macklin Biochemical Technology Co., Ltd. (Shanghai, China). Sodium dodecyl sulfate (SDS) was selected as an anionic surfactant. Dodecyl trimethyl ammonium bromide (DTAB) was selected as a cationic surfactant and the molecular structures are shown in Figure 3. The water used in the experiment was tap water. The concentration of foaming agents was controlled at 10 g/L to decrease concentration interference [17 (link)].
The two foaming agents were foamed using the F80 portable bubbler. The foam densities of DTAB and SDS are 22.38 kg/m³ and 37.77 kg/m³. The changes in settling distance and water secretion of prefabricated foam within 1 h were measured according to Chinese standard JC/T2199-2013 [24 ] Foaming agents for foamed concrete, China, 2013, and the results are shown in Figure 4. The foam heights of the SDS and DTAB were 142 mm and 121 mm and the bleeding heights were 11.5 mm and 6 mm, respectively.