This construction and landscaping material is washed and screened to produce a clean and uniform gravel. Often simply called Pea Gravel, old-timers call it Chat, but these are inaccurate, generic terms. There are several sizes of pea gravel, and genuine Chat is a lead mining by-product not available in North Carolina.
Like all gravel products, 78M is a specifically engineered aggregate. In North Carolina, it is clean, crushed granite, with most pieces ranging between 3/8″ to 1/2″ long. There is very little of smaller pieces or fines.
This brings you an attractive landscaping material for walkways and decorative flower beds, for mulching around plants and shrubs, and for splash protection under building eaves. It is sometimes used for children’s play areas, and sometimes for dog kennels. 78M washed stone lets water through reasonably well, so it rinses clean in the rain.
78M washed stone is sometimes applied with hot tar on large, flat asphalt roofs; smaller aggregate is equally popular for this. It is also commonly used in mixed concrete for building foundations.
Roads & Driveways
Almost all 78M produced goes to highway and road surfacing, mixed either with concrete or hot asphalt. A great deal goes for track ballast on railroad tracks. Packing the cross ties on all sides with this aggregate protects them from moisture and helps them bear up under heavy trains.
78M is often spread on snow-covered roads and driveways for better traction. On residential and commercial properties, it makes an excellent top cover for driveways, gravel roads and parking lots, when laid down over a few inches of Crusher Run Gravel. Property owners find that this choice makes a durable and cost-effective surface that is easily upgraded to an asphalt surface even years later, since the same size stone is used for blacktop paving.
Because it is a somewhat loose, angular gravel, 78M will move with rushing water, and will slide downhill on steep roads or driveways. For mulching purposes, it is fine to lay it directly on soil, where it will protect from erosion and keep weeds down somewhat. It’s an attractive and long-lasting mulch. But on an area getting foot or vehicle traffic, a base layer of Crusher Run Gravel or some similar moisture-resistant layer is essential to keep this aggregate from sinking into the dirt over time. It needs a firm surface underneath to make a good traffic surface.