#7 Trap Rock (1/2")

#7 Trap Rock (1/2") Crushed Stone: Technical Overview and Applications

#7 Trap Rock (1/2"), also known as 1/2" Trap Rock, #7 Crushed Stone, #7 Aggregate, or 1/2" Clean Stone, is a dense, hard, and angular crushed stone commonly produced from igneous rock such as trap rock or basalt. The nominal particle size is approximately 1/2 inch, with most pieces passing a 3/4" sieve and retained on a 3/8" sieve. The material is typically dark gray to black, chemically stable, and has low porosity. It is washed to remove fines and is free from organic material, clay, and silt. The high resistance to abrasion and weathering makes it suitable for demanding construction and landscaping uses.

Material Characteristics

• Crushed, angular stone for strong interlock
• Size: 3/8" to 3/4" (nominally 1/2")
• Color: Dark gray to black
• Hard, dense, and durable
• Non-reactive and low porosity
• Bulk density: 100-120 lbs/ft³ (varies by source)
• Specific gravity: ~2.6-2.9

Performance Properties

• High resistance to abrasion (Los Angeles Abrasion typically < 40%)
• Excellent compaction and interlocking ability
• Good drainage characteristics when washed
• Resistant to weathering and freeze-thaw cycles

Common Uses and Practical Applications

#7 Trap Rock is widely used as a toplayer for driveways and parking lots, providing a stable, durable surface that resists displacement. Its angular shape allows the material to interlock, reducing movement under traffic and load. The stone is also well-suited as ground cover for erosion control and as a base material beneath concrete, pavers, sidewalks, and roadways. In drainage systems, such as French drains and pipe bedding, it helps manage water flow and prevent accumulation.

Other typical applications include backfill for retaining walls, railroad ballast (in smaller sections), septic system drain fields, and as an underlayment for pavers. In landscaping, it serves both functional and decorative purposes, though color uniformity may vary.

Typical Applications Table

Limitations and Incorrect Applications

#7 Trap Rock (1/2") should not be used as a surface material for playgrounds, as the angular stones can cause injury. It is not intended as a fine aggregate (sand replacement) in concrete or mortar. This material is not suitable where a smooth, compacted finish is required, such as on finished driveways or walkways. Use is also limited in applications requiring high permeability with no fines, unless the product is specifically washed and screened for that purpose. Color may vary, so it is not recommended where uniform decorative appearance is essential. For high-alkali environments, ensure the stone has been tested for alkali-silica reactivity.

Comparison Table

Product Availability, Pricing, and Delivery

#7 Trap Rock (1/2") is available for delivery in bulk quantities across the United States. Prices vary based on location, local supply, and delivery distance. All listed prices include delivery. To see accurate pricing for your area, enter your ZIP code on our website. Below is a sample of current pricing in selected cities:

Delivery is included in every price shown. The final cost depends on your ZIP code and the delivery location. You can order online in less than a minute and choose your preferred delivery date and time slot.

Ordering and Delivery Information

Ordering #7 Trap Rock from Gravelshop is straightforward. Enter your ZIP code to view local prices, add the product to your cart, and check out. All prices include truck delivery, with no hidden fees. We do not offer spreading or landscaping services; material is delivered and unloaded at the most suitable location based on road access and driver discretion. If you are not present at the time of delivery, you accept responsibility for the material left unattended. Delivery requires road access at least 12 feet wide and suitable for heavy trucks. If access is not possible, the driver will unload as close as possible, and full haul cost applies for missed deliveries.

Payment can be made online using major credit cards and digital payment services. After ordering, you will receive a confirmation email with payment and shipping details. Gravelshop supplies landscaping material and aggregates in 31 U.S. states, with logistics managed through independent haulers. Delivery times may vary due to supply or transport constraints. You always have a right to withdraw within 14 days of receiving the goods.

Summary of Key Product Features

• Great as a toplayer for driveways and parking lots
• Effective ground cover for erosion control
• Can be used as a base material for concrete, pavers, and roadways
• Provides good drainage and interlocks for stability
• Not suitable for playgrounds, fine aggregate use, or where a smooth, compacted surface is required

For accurate coverage estimates, use our online material calculator. If you need help or have questions, contact Gravelshop support by phone, email, or through our website. All prices include delivery, and you can select your preferred delivery date and time during checkout.