Reduction of fractures in dried clay-like materials due to specific surfactants

The possibility of fracture reduction as a result of application of specific surfactants during intensive drying of clay-like materials was examined in this paper. The dodecyl sulfate sodium salt (SDS) and the fluoric (FC 4430) surfactants were used for the tests. Different amounts of these surfactants were mixed with distilled water and used for wetting a dry clay material before forming clay samples. The clay samples in the form of cylinders 44 mm in diameter and 50 mm high were extruded and after leveling the moisture distribution subjected to convectively drying in hot air at 120 °C. The acoustic emission (AE) method was used to monitor on line the development of crack formation in dried samples. It was stated that application of surfactants in a prescribed amount may significantly reduce the drying induced fractures in clay during its intensive drying and thus to obtain good quality products by high drying rates.