A curb is a step where the roadbed meets the sidewalk or other raised pathway. Curbs serve three functions: a gutter to convey rainwater and detritus from the roadbed and sidewalks to the catch basins at the ends of the street; a visual and physical limit to the vehicular roadbed; and a finished edge to sidewalks and roadbeds.
This is the standard method for installing concrete curbs. The mixture is comprised of cement(s), aggregate(s), water, and other possible chemical admixtures, such as air entrainer and pigment. When the mixture is finished, it is allowed to harden, forming a solid curb. Concrete curbs can be pigmented to match the adjacent sidewalk.
Granite cut to long sections and laid as curbing. Saw-finishing, achieved by cutting the granite with a stone saw and polishing out saw marks, provides a smooth, clean look. Split finishing, typically achieved by hand-chiseling, exposes the natural cleft of the stone, giving a rough-hewn texture.