Milling is an impact process that chips small pieces of concrete from the pavement surface. Diamond grinding is a cutting process. For grinding asphalt to remove old pavement, see pavement milling. Applications There are many surface issues that diamond grinding can improve or correct. Some of the surface imperfections that can be addressed by diamond grinding include: faulting at joints and cracks, built-in or construction roughness, polished concrete surfaces exhibiting inadequate macrotexture, wheel path rutting caused by studded tires, unacceptable noise level, slab warping caused by moisture gradient and construction curling, inadequate transverse slope and splash and spray reduction. Cost-effectiveness Diamond grinding is a cost-effective treatment, whether used alone or as part of an overall concrete pavement restoration (CPR) program. In most cases, the cost of diamond grinding is only about half the cost of bituminous overlays. This cost competitiveness, in conjunction with eliminating bituminous overlay problems (rutting, corrugation, poor skid resistance, drainage reduction, vertical clearance reduction) makes diamond grinding an alternative for many rehabilitation projects. Diamond grinding can be used as part of any preventive maintenance program for concrete pavements. Caltrans reports that the average life of a diamond-ground surface is between 16 and 17 years. On average, more than 2,000 lane-miles of concrete pavement are diamond ground every year. Benefits At the cost of employing diamond grinding equipment, several benefits are observed. The process is used to restore or improve pavement ride quality. Restoring ride through grinding improves traffic carrying capacity and adds value to an in-place pavement. Diamond grinding provides numerous benefits over other rehabilitation alternatives. This repair technique also provides a smooth surface which is often as good as new pavement. As trucks travel across bumps and dips, they bounce vertically on their suspension resulting in dynamic loading on the roadway. The increased load due to dynamic impact results in higher stresses in the pavement materials and consequently lower road life. By providing an extremely smooth surface, diamond grinding limits dynamic loading. A potential benefit of diamond grinding may be reduced road noise, depending on the grinding technique used and the surface texture that is left. A longitudinal texture can provide a quieter surface than many transverse textures. A multi-state study on noise and texture on PCC pavements concluded that longitudinal texture concrete pavements are among the quietest pavements for interior and exterior noise. Diamond grinding can also remove faults by leveling the pavement surface, thus