Understanding Anchor Strength and Guide Loads
Our anchors use adhesive bonding to secure attachments to asphalt. Holding strength depends on the installed system: the anchor, adhesive, pavement, installation, and loading conditions.
Our pull tests measure how installed anchors respond to a short-duration vertical pull. Choosing an anchor for a particular application also requires considering pavement temperature, load duration, repeated impacts, and acceptable movement.
What the Numbers Mean
Section titled “What the Numbers Mean”| Term | Meaning |
|---|---|
| Guide load | The load we suggest designing to for a short-duration force (about a minute or less) on an anchor installed per our instructions in 3” asphalt. For a continuous load, such as a strap under tension for months, use 20% of the guide load; see Loading Guidelines. It is guidance based on our testing, not a certified rating or a site-specific allowable load. |
| Measured peak pull force | The highest force recorded during an individual pull test. An average describes the tests included in that group, not a guaranteed minimum for another installation. |
| Application load | The force the installed anchor must resist in use. Its direction, duration, repetition, and the movement the attachment can tolerate all matter. |
| Model | Duty | Bolt | Pull guide load | Side guide load |
|---|---|---|---|---|
| SP10 | Light | 3/8” | 900 lb | 750 lb |
| SP12 | Medium | 3/8” | 2,000 lb | 1,500 lb |
| SP18 | Heavy | 7/16” | 2,000 lb | 1,500 lb |
| SP58 | Extra heavy | 5/8” | 2,000 lb | 1,500 lb |
How we set the guide loads: The pull guide load is about half the low end of our pull results on pavement below 90°F. That keeps it below the low end of our results on 120°F pavement, where pull resistance drops by about 40%. The side guide load is the force at which an anchor starts to shift sideways in our tests, not the force at which it fails.
Why the SP12, SP18, and SP58 share the same numbers: In 3” asphalt, these three anchors resist about the same pull because the asphalt, not the anchor, sets the limit. A larger anchor does not add pull strength there. Its larger bolt and body hold up better to repeated impacts, metal fatigue, and sideways forces that can bend or break a smaller bolt. The duty labels reflect that durability. Choose a heavier-duty anchor for impacts, vehicle traffic, and repeated loads.
See the pull test methodology for how we measure performance and the temperature results for how measured peak force changes with pavement temperature.
What Our Pull Tests Show
Section titled “What Our Pull Tests Show”In most testing, peak pull force occurs with less than 1/4 inch of movement. Once the asphalt starts to move, we generally observe decreasing force. An anchor may continue to resist pull as it moves, but that remaining resistance should not be counted as additional usable capacity or dependable warning before failure.
Movement can make an attachment unsuitable for service even while the anchor still resists load. The movement thresholds used to describe our tests are not allowable movement limits for every application.
Slow pull and side-load tests do not represent repeated impacts. For the measured displacement points, equipment, procedure, and test videos, see Pull Test Methodology.
What Affects Installed Strength
Section titled “What Affects Installed Strength”- Pavement: Thickness, condition, asphalt mixture, and the supporting base affect the installation. Our reference testing uses 3-inch PG64-16 asphalt. See Asphalt Thickness.
- Temperature during use: Hot pavement can reduce pull resistance after the adhesive has cured. Our temperature results show the measured effect and its limits.
- Loading: A brief vertical pull test does not establish performance under sustained tension, repeated loading, or sideways forces. The load on each anchor and the movement the attachment can tolerate matter.
- Installation: Correct hole preparation, adhesive selection, and curing are essential. Follow the installation guide and hole-cleaning procedure.
- Moisture during installation: EPX2 requires dry conditions. EPX3 permits wet installation when used according to its instructions. See Weather and Temperature Installation.
Correct installation is essential, and pavement and operating conditions still determine how much the installed anchor can resist.
Choosing for Your Application
Section titled “Choosing for Your Application”Review the installation requirements for the anchor model. Consider the actual force on each anchor, how long it acts, whether it repeats or comes from impacts, the hottest expected pavement conditions, and whether movement would affect the attachment.
For critical applications, sustained tension, or uncertain pavement conditions, contact us with the attachment details, pavement thickness and condition, expected loads, and operating temperatures. Site-specific testing can help evaluate the installation under the conditions tested; a brief pull test alone does not establish long-term performance.
ICC-ES Certification
Section titled “ICC-ES Certification”Our anchors do not have an ICC-ES evaluation report. ICC-ES acceptance criteria for anchors, AC193 for mechanical anchors and AC308 for adhesive anchors, are written for anchors installed in concrete. We are not aware of an ICC-ES acceptance criterion or ASTM test standard for anchoring into asphalt.
In place of third-party certification, we publish our own test information, including our pull test methodology and videos and measured temperature results. If your project requires certification or a particular approval, contact us to discuss the available test information and your project’s requirements.