Does the type of aggregate used in a pavement affect its skid resistance?
Yes it does. Angular aggregates tend to be more effective than rounded, though this effect diminishes with time as the aggregate becomes polished by traffic. The more wear-resistant aggregates retain their skid resistance longer. Limestones, especially those containing mostly calcium carbonate, tend to be more rapidly polished by traffic. Their skid resistance can be improved by replacing 25 percent of the fine aggregate with silica sand.