What is the difference between clean and minus? What size of crushed rock do I need? We have the answers to these and other questions.
How is crushed rock made?
The Kapowsin Quarry area was tested in the past and found to have large deposits of a hard rock called basalt. Deep holes are drilled in the rock and filled with dynamite, then the rock is blasted. Some of the large pieces that break off are kept for projects like creating rock walls or building seawalls. Most of the pieces are loaded into a machine that crushes them into smaller pieces. The pieces are sorted by using screens with different sizes of holes.
What is the difference between clean and minus (for example, 1¼” clean versus 1¼” minus)?
Clean rock products contain no fines (small particles of ground rock).
Minus rock does contain fines. Fines help a product compact. For example, if you’re building a driveway over soft ground, a minus product can compact and stay in place.
Watch the video to see the difference between crushed clean and crushed minus rock products.
What size of crushed rock do I need?
It depends on the application. Here are some basic guidelines.
| Application | Product Recommendation |
|---|---|
| Driveways Used by Light Cars | 5/8″ Minus (Compaction Needed) or 1¼” Clean (No Compaction Needed) |
| Driveways Used by Heavy Equipment | 1¼” Minus (compaction needed) or 1¼” clean (no compaction needed) |
| Garden Walkways | ¼” Minus Trail Mix |
| Rock Walls | 1-Man and Up + Quarry Spalls + 1¼” Clean or 1½” Drain Rock (for Drainage) |
Who will install my rock product?
Unfortunately, Washington Rock doesn’t provide contractor services. However, local landscaping companies can usually install rock walls and water features. There are also companies that specialize in rock installation. If you plan on finishing your own driveway, you can go to an equipment rental company for skidsteers, excavators, and more.
What is Kapowsin Blue rock?
Kapowsin Blue rock is a blue-gray rock that is unique to Washington Rock Quarries. The color is especially pronounced when the rock is wetted, such as after rainfall.
How much does it cost?
We have a picked up pricing sheet we can provide at your request. For deliveries, cost depends on where the product will be delivered. The farther trucks have to travel, the more gas that is used and the more time that is spent. That’s why we provide a form on our contact page to request a quote.
For more information about Washington Rock’s driveway rock products, visit our Driveway Rock Products page. For other common questions, check out “What Does a Cubic Yard Look Like?” and “Choosing the Right Rock: Comparing Rock Sizes and Types.”