A Study of nozzle angle in stone surface treatment with water jets

► Surface treatment quality with water jets depends on nozzle angle. ► Surface roughness is small at low and high nozzle angles while it is high at moderate angle. ► Variogram analysis of the profiles indicates the presence of high anisotropy ratios for low and high nozzle angles. ► Surface treatment with water jet between 30° and 75° angles yields better surfaces from the esthetic point of view. The stone surface treatment with water jet is a recently introduced method. It is used to increase the roughness to improve its antislip properties while preserving esthetic appearance of the stone without having thermal shock, mechanical stress and the production of fumes and dust. Nozzle angle is one of the important parameters affecting treatment of surface. This study is an attempt to assess the effect of nozzle angle on surface treatment quality with water jet and to determine the most suitable nozzle angle value. For this purpose, surfaces of Sardinian Basalt samples are treated with pure water jet in six different nozzle angles (15°, 30°, 45°, 60°, 75° and 90°). The roughness is measured on all the treated surfaces by various roughness parameters. The experimental studies showed that treatment with nozzle angle between 30° and 75° gives the surfaces with similar regular variation.