Choosing the Right Surface for Our Shared Road

01Purpose of this memo

This document records the research, reasoning, and decision-making behind our plan to use Class 6 Aggregate Base Course as the surface material for the upcoming Spring road work on our shared community road.

We want everyone in the community to be able to see clearly that:

1. Both materials — Class 6 and recycled asphalt (RAP) — are legitimate, widely-used choices.
2. Neither is universally right; each has documented trade-offs.
3. Our choice is grounded in (a) the specific current condition of our road, (b) the equipment we own, (c) the maintenance model we are committing to, and (d) published guidance from FHWA, CDOT, EPA, USDA, and industry sources.
4. We are committed to course-correcting if Class 6 underperforms our expectations.

02Quick summary

03Where the road is today

For the last ~8 years the shared road has been resurfaced with RAP recycled asphalt. Before that, for ~20+ years, it was Class 6 road base.

The current state of the road, after 3 years without new material:

• Inconsistent surface. Large sections have hardened into asphalt-like crust, while adjacent sections remain soft, with potholes, washboarding, and ravel (loose flaking).
• Hard/soft transitions. The interfaces between hardened RAP and soft material are the worst-performing zones — they shear, pothole, and require disproportionate maintenance.
• Drainage issues. Berms blocking ditches in places; insufficient crown in others.
• Inconsistent hardening from the start. The original RAP installations didn’t use a water truck or roller-compactor either — hardening depended on luck with weather and binder content. The result has always been spotty: roughly 20% of the road hardened well, with the rest staying soft or inconsistent. We don’t have a path to do better than that with the equipment available.

This condition was confirmed independently by Don Miller of Mountain Dirt Works, LLC (Estimate 25-56, August 2025), who walked the road for 3.5 hours and concluded that the hardened sections needed to be broken up before any new material is added, regardless of which material is chosen, because new material laid on top of the hard crust will erode and shear off rapidly.

04Material comparison

4.1 Class 6 Aggregate Base Course our choice

What it is: A blend of crushed rock (commonly recycled concrete in Colorado), gravel, sand, and fines, graded to CDOT specification. The material we are sourcing from Colorado Aggregate Recycling is 100% recycled concrete that meets CDOT Class 6 gradation requirements.

Strengths

• Excellent compaction due to a well-graded mix of particle sizes from 3/4" down through fines.
• Easy to maintain. Per industry guidance and FHWA: easily regraded and re-compacted as needed.
• Standard for county roads. Jefferson County and most Colorado counties use Class 6 (or equivalent) for unpaved and base-course applications, per CDOT 2023 Standard Specifications, Division 300.
• Good drainage with controlled fines — the fines hold the road together while still allowing controlled drainage.
• Forgiving for owner-operators. Mistakes during grading can be corrected on the next pass — the material doesn’t “set” into something unfixable.

Weaknesses

• Dust can be higher than RAP in dry conditions. Mitigation: magnesium chloride dust palliative, the standard treatment used by Western counties.
• Plows can scrape it off more readily than hardened RAP, requiring periodic top-up.
• Slower snowmelt than dark RAP surface.

4.2 Recycled Asphalt Pavement (RAP / asphalt millings) considered

What it is: Old asphalt pavement that has been removed, ground up, and reprocessed. Contains residual asphalt binder plus original aggregate.

Strengths

• Self-binding when conditions are right (warm weather, good compaction, even moisture).
• Faster snowmelt (dark surface absorbs solar heat).
• Lower dust once hardened.
• Resists plowing-off once cured.

Weaknesses (documented and observed on our road)

• Difficult to maintain. Per G&G Services’ side-by-side comparison: “More difficult to maintain once installed, as it forms a more solid and cohesive layer. It isn’t something that can be easily ripped up and regraded.”
• Inconsistent batches. Don Miller (Mountain Dirt Works) and multiple industry sources note that recycled asphalt is an inconsistent product because residual oil/binder content varies batch-to-batch.
• Requires water + compaction for proper installation. Without a water truck and roller, results are highly variable — exactly the situation we are in.
• Hard/soft transition problem — the issue our road currently exhibits.
• Pothole repair is harder. Cold-patching hardened RAP with new RAP is documented as one of the more difficult patching scenarios; specialized infrared patching or hot-mix is recommended (NJDOT pothole repair study) — we have neither.
• Environmental considerations. Studies show low but non-zero leaching of PAHs (some EPA-listed probable human carcinogens) and metals from RAP, particularly in the first few years (Univ. of Florida critical review; FHWA-NJ-2017-008). Field levels are usually below EPA thresholds, but the concern is non-zero, especially for material in stormwater paths near homes and wells. Class 6 (recycled concrete) does not have this concern.

4.3 Cost

At our local supplier, Colorado Aggregate Recycling (near the Jefferson County landfill), Class 6 and recycled asphalt are priced identically per ton. Trucking distance from CAR is also approximately one-third of the trucking distance from APC (the supplier originally proposed for RAP), so total delivered cost favors Class 6 from CAR.

05Side-by-side scorecard

The chart below scores each material on the criteria most relevant to our specific situation — owned equipment, no compaction infrastructure, new operators, current alternating hard/soft surface. Higher is better.

5.1 Direct comparison table

06Why Class 6 fits our situation

The published comparison shows both materials work in different contexts. Here is why our specific context favors Class 6:

6.1 We own the equipment for frequent, light maintenance

Our toolbox:

• A motor grader (the former Rapp grader, now For the Grader Good, LLC)
• Shaun’s tractor with bucket, back blade, and box blade with tines
• Lee’s bobcat available on a neighborly basis

This equipment set is ideal for the Class 6 maintenance model: frequent, light grading after rains and shoulder seasons, periodic blading to redistribute material from edges back to the crown, and occasional top-ups.

It is not ideal for the RAP maintenance model, which depends on:

• A water truck (we don’t have one; per Mountain Dirt Works, sourcing water at scale is prohibitively expensive due to Colorado water rights)
• A heavy roller-compactor (we don’t have one)
• Carefully timed installation around weather windows
• Specialized cold/hot-mix patching for failures

Using the equipment we actually have to maintain the material best suited to that equipment is sound asset management.

6.2 RAP has produced an inconsistent surface here, every time

Across multiple RAP applications over ~8 years, only about 20% of the road has actually hardened well — the rest stayed soft or inconsistent. This isn’t a maintenance failure. It’s the predictable variability of recycled asphalt installed without water trucks and compaction equipment, with binder content that varies batch to batch. Putting more RAP down without adding that compaction infrastructure is statistically likely to repeat the same 20% / 80% pattern.

Class 6 doesn’t depend on weather luck or batch chemistry to perform. It compacts predictably under traffic and rain across the entire road surface, not just in lucky stretches.

6.3 Class 6 lowers the consequence of operator error

We are new to operating the grader. Industry guidance (FHWA Gravel Roads Guide) is consistent: a learning curve is expected, and the ability to correct mistakes on the next grading pass is essential. Class 6 supports this; RAP, once it sets, does not.

“We are going to miss [Phil’s] skill on that grader for a little bit while the new owners get their skills up to speed.” — Lee Bagby, community email, Oct 28, 2025

The material we put down should be forgiving while we develop those skills.

6.4 Crown and drainage repair are easier in Class 6

FHWA recommends a ~4% crown for gravel roads. Re-establishing crown on a road with hardened RAP sections is materially harder than re-establishing crown in fresh, gradable Class 6. Crown and ditch maintenance are the two largest contributors to road damage on rural gravel roads (FHWA Gravel Roads Guide, Section 5). Class 6 makes both easier.

6.5 Reversibility

If, after a season or two, Class 6 underperforms our expectations, we can grade it, top it, or switch back to RAP without major loss of investment. The reverse — switching off RAP back to Class 6 — is what we are doing right now, and it required breaking up the hard crust first, at significant labor cost.

07Addressing specific concerns

7.1 “We’ve grown the hardened areas successfully — why change?”

We respect this experience. RAP did harden in roughly 20% of the road over the years, which is a real result. However, the broader picture is more mixed:

• The road has degraded over the last 3 years without input. The current alternating hard/soft pattern is hard to maintain with our equipment set.
• Industry literature explicitly warns about this maintenance approach with hardened RAP. Per the G&G Services side-by-side comparison: hardened RAP “isn’t something that can be easily ripped up and regraded” — spot-fixing the soft transitions next to hardened areas tends to become a recurring whack-a-mole pattern rather than a one-time fix.
• Two long-tenured caretakers of this road hold differing views on whether RAP is the long-term right call. This is a legitimate disagreement among experienced people, not a settled question.

7.2 “Class 6 has more dust”

True, in dry conditions. Standard mitigation: magnesium chloride dust palliative, applied 1–2× per year, used by virtually every Western county on gravel roads (FHWA Unpaved Road Dust Management). We can budget for this if/when dust becomes an issue, well within historical road-spend levels.

7.3 “Class 6 needs to be re-upped every year”

Partially true — some top-up is normal for Class 6 because plows scrape some off and traffic redistributes it. But:

• Material costs are equal per ton.
• We can place top-ups strategically (potholes, low spots) rather than full resurfacing — the same approach Lee suggested for RAP.
• This community successfully used exactly this approach — strategic top-ups on Class 6 — for the ~20+ years before the switch to recycled asphalt. (Long-tenured neighbors can confirm or correct this history.)

7.4 “You said you can’t compact properly without a roller”

Correct, and this applies to both materials. Per FHWA, natural compaction by traffic + well-timed rain events is how most county gravel roads compact — and it works for Class 6. That’s the same model used on this road for the ~20+ years of Class 6 history before the switch to RAP. Class 6 is more forgiving of imperfect compaction than RAP, because un-fully-compacted Class 6 still grades smoothly; un-fully-compacted RAP ravels and creates the hard/soft problem.

08Maintenance plan going forward

We are committing to a more frequent, lighter-touch maintenance schedule than the road has received in recent years.

1. Spring (after snowmelt / mud season ends): full grading pass, crown re-establishment, ditch/shoulder check, material top-ups where needed.
2. Early Summer: light grading, dust palliative if needed.
3. After significant rain events: spot grading on potholes and washboard before they grow.
4. Fall (before plowing season): final smooth, ditch clearing, prep for snow.
5. As-needed: pothole spot-fixes — easier with Class 6.

This schedule leverages the fact that we own the equipment and live on the road. The marginal cost of “another pass with the grader” is fuel + an hour or two of our time, which is not billed to the community per our community agreement.

09Sources & references

All links open in a new tab.

1. Colorado Aggregate Recycling — Class 6 Road Base Explained — our local supplier; describes their CDOT-conforming product.
2. Colorado Aggregate Recycling — CDOT Class 6 conformance test report (PDF, 2022)
3. G&G Services — Comparing Class 6 Road Base and Recycled Asphalt (May 2024) — primary side-by-side industry comparison.
4. Federal Highway Administration / SD LTAP — Gravel Roads Construction and Maintenance Guide (FHWA-OTS-15-002) — the standard U.S. reference for gravel road maintenance.
5. CDOT Standard Specifications for Road and Bridge Construction (2023), Division 300 — Aggregate Base Course
6. Jefferson County Transportation Design & Construction Manual — references CDOT specs for road base.
7. EPA — Gravel Roads: Dust Control and Stabilization (PDF)
8. USDA Forest Service — Dust Palliative Selection and Application Guide (PDF)
9. FHWA — Unpaved Road Dust Management: A Successful Practitioner’s Handbook
10. Mountain Dirt Works, LLC — site walk and verbal report (Don Miller, Aug 2025). Estimate 25-56. Direct quote on RAP batch inconsistency.
11. Greenfield Pavement — Performance of Recycled Asphalt in Various Weather Conditions (Jul 2024)
12. NJDOT — Innovative Pothole Repair Materials and Techniques (PDF)
13. Townsend et al. — A critical analysis of leaching and environmental risk assessment of reclaimed asphalt pavement (Univ. of Florida, PDF)
14. NJDOT / FHWA-NJ-2017-008 — Environmental Impacts of Reclaimed Asphalt Pavement (PDF)
15. KH Plant — Building a Great Gravel Road: 10 Basic Principles
16. TRB Webinar — Gravel Roads Design and Maintenance (PDF, slides)

10Closing note

We genuinely welcome continued input — including disagreement — from neighbors who have lived with and worked on this road longer than we have. The choice between Class 6 and RAP is not a moral question and it is not an engineering certainty. It is a judgment call about fit between material, equipment, operator skill, and maintenance cadence.

We have made our judgment call, documented above, and we are committed to:

• Doing the work ourselves at no labor cost to the community.
• Using our own equipment.
• Owning any mistakes and fixing them at our own time.
• Reporting back honestly on how Class 6 performs through the first season and reconsidering openly if it underperforms.

Thanks for reading. Onward.

— Shaun & Trevor
For the Grader Good, LLC