WHEN CONCRETE AND ASPHALT GO TO WAR

WHEN CONCRETE AND ASPHALT GO TO WAR

THE PROBLEM

Across Canada, highway engineers face a problem that has stubbornly resisted easy solutions for decades: composite pavements. Sections of highway built on aging Portland cement concrete — then overlaid with asphalt — behave like two incompatible materials forced into an uneasy partnership.

Concrete is rigid. It expands and contracts in slabs. Asphalt is flexible. When you put one on top of the other, the concrete wins. Its joint movements and thermal cracks telegraph upward through the overlay, typically within a single winter. The result: reflective cracking — surface failures that mirror the deterioration below, accelerating decay and driving up maintenance costs year over year.

Asphalt pavements are inherently strong in compression but vulnerable to tensile failure — the primary driver of cracking under vehicle loads and thermal cycling. For New Brunswick DTI, Route 8 near Miramichi represented exactly this challenge: 6.7 km of two-lane highway over 38-year-old concrete pavement, severely cracked, jointed, and generating high-strain slab movements with every freeze-thaw cycle.

“The maintenance and repair of composite pavements is complex and expensive due to the movement of the underlying slabs and the resultant reflective cracks due to the mismatch of rigid concrete and flexible asphalt.”

— Michael J. Simons, P.Eng. — NSUPA Presentation, April 9, 2026

THE TECHNOLOGY

WHAT ARMI ACTUALLY IS — AND WHY IT WORKS

Among synthetic reinforcement materials evaluated over three decades, para-aramid (aromatic polyamide) has emerged as the leading candidate due to its exceptional strength-to-strain ratio, thermal stability, and full compatibility with standard asphalt production. Standardized under ASTM D8395-23 as ARCA (Aramid Reinforced Composite Asphalt), it has been deployed across all provinces and two territories in Canada.

Para-aramid achieves three critical functions in an asphalt mix:

• Mechanical bonding — with aggregate surfaces via controlled fibrillation of the fiber surface
• Tensile reinforcement — within the binder matrix — resisting crack-opening forces that standard mixes cannot
• Lateral restraint — of the mat during compaction — improving density at unconfined edges and producing superior construction joints
• Khan et al. (2024) — four-point bending fatigue testing showed ARCA outperforms control mixes at all strain levels (400, 600, 800 με). Digital image correlation confirmed stress dispersion over wider areas, slowing crack propagation.
• Blankenship et al. (2024) — FWD and Automated Plate Loading Technology confirmed a ≥20% increase in AASHTO Structural Number for ARCA-reinforced sections.
• Blankenship & Bausano (2024/2025) — 20–25% service life extension modeled as a 10% reduction in 50-year cradle-to-grave environmental impacts.
• Coleri et al. (2017) — significant improvement for 38mm aramid over both control and 19mm aramid. University of Alberta (Saleh et al., 2022) confirmed a 7% rutting gain via Hamburg Wheel Tracker.
• Flexibility Index — 38mm aramid increased FI by ~37% over control. 19mm showed no statistically significant improvement.
• NB DTI Route 8, Miramichi — 6.7 km HSAI on 38-year-old concrete, 2024. Zero reflective cracking after winter one.
• Alberta Transportation Hwy 16, Sherwood Park — 2km HSAI over chemically stabilized soils, 2024.
• MTO Contract 2023-4030, Hwy 401 Napanee ON — Composite pavement, full BMD using IFIT, SCB, DCT, Hamburg, beam fatigue. Paving 2024 and 2025.

The standard specification calls for 38mm para-aramid fiber at the ASTM Standard dosage of 65 g/tonne (2.1oz / ton) of asphalt mix. At this dosage, more than 10 million individual reinforcing elements are distributed throughout each tonne, creating a continuous three-dimensional tensile reinforcement matrix. The fiber is treated with Sasobit® wax to prevent collection by plant dust systems; above 90°C it becomes fully soluble in asphalt cement, leaving no residual effect.

THE EVIDENCE

LABORATORY PERFORMANCE — WHAT THE RESEARCH CONFIRMS

A substantial body of peer-reviewed and government research supports the performance benefits of 38mm ARCA:

ROUTE 8 — THE DECISION

THREE OPTIONS, ONE CLEAR ANSWER

In November 2023, NB DTI evaluated three rehabilitation paths for Route 8, Williamstown Road Area (CS 14, 2.100 to 8.131) against a $7M budget, as documented in M. Sweezie’s Route 8 Concrete Highway Rehab Options report.

The flexible interlayer — specifically the High Strain Asphalt Interlayer (HSAI) reinforced with aramid fiber — offered something the other options could not: a technically engineered solution within budget, with local execution, and proven precedents in Ontario and Alberta. Technical support was provided by Surface-Tech, BATT and VA Asphalt Paving Technologies.

CASE STUDY IN THE FIELD ROUTE 8 — CONSTRUCTION

THE HSAI PAVEMENT STRUCTURE

The contract was awarded to Eurovia Maritimes (Northern Contracting), with construction completed in 2024. The pavement structure above the existing 200mm Portland cement concrete was designed in three layers:

Aramid fiber conforming to ASTM D8395-23 was dosed at the plant at 130 tonnes per hour. A trial section was completed at least one full working day before production — confirming volumetrics, dosing calibration, and roller protocols. HSAI mix QC confirmed: AC content 8.7%, Air Voids 1.4% (spec: 0.5–2.5%), VMA 22.3% (spec: >16%), Hamburg 4,520 passes @ 45°C (spec: >4,000), CT Index 416.3 (spec: >300). DTI QC testing confirmed AC content 8.72%/8.64% and air voids 1.77%/2.41%.

“Get the rollers on as soon as possible — it’s a thin section and it cools quickly. Once flushing is observed, density has been achieved.”

— Michael J. Simons, P.Eng. — Lessons Learned, NSUPA April 2026

FIELD PERFORMANCE

THE RESULTS — ROUTE 8 AND BEYOND

Asphalt overlays on jointed concrete typically crack within months of their first Canadian winter. Route 8 showed zero reflective cracking after its first winter. The only distress observed was settlement at culvert crossings — a subgrade issue unrelated to the interlayer. The project is finishing its second winter (2025–2026). New Brunswick DTI, deploying ARCA provincewide since 2022 and testing with the University of New Brunswick, reports: very pleased with performance to date.

A smart pavement monitoring system with GPS-tagged high-resolution imaging was deployed across three benchmark Canadian ARCA projects in June 2025 (PCI per ASTM D6433: 85+ = Good; <70 = Rehabilitation needed):

The York Region project is the most compelling field demonstration: seven years post-construction, ARCA lanes score 84 (Good) versus 53 (Rehabilitation Needed) for the unreinforced control — a 31-point PCI differential under identical traffic and environmental conditions. The Barber Drive result confirms ARCA can outperform established geogrid reinforcement.

ADOPTION

CANADA IS SPECIFYING ARMI AT SCALE

As of 2025, ARCA has been deployed across all provinces and most territories in every pavement asset class. Three major Canadian HSAI deployments were completed or underway in 2024–2025:

Broader adoption spans: ~10% of Ontario’s 444 municipalities use ARCA in ongoing annual road programs, several continuously since 2017. Airports include Toronto Pearson, Calgary, Vancouver, Halifax Stanfield, and multiple DND military airfields. Pacific, Atlantic, and Great Lakes port facilities, intermodal container terminals, and logging truck corridors are all active use cases.

COST & LIFECYCLE

THE ECONOMICS OF ARMI

The Ontario MTO reports a 12–15% premium per tonne of HMA/WMA. Municipal tender data indicates $15–20/tonne when aramid dosing is a separate tender item. On a per-area basis this equates to approximately $2–3 per square metre for a standard 50mm lift. Use $20/tonne for owner cost modeling.

LESSONS LEARNED — NSUPA 2026

WHAT THE FIELD TAUGHT US ON ROUTE 8

CONCLUSIONS & RECOMMENDATIONS

RECOMMENDATIONS FOR OWNERS & SPECIFIERS

The evidence base for ARCA using 38mm para-aramid at 65 g/tonne is robust, consistent across laboratory and field settings, and supported by independent government and academic research.

1. 38mm aramid at 65 g/tonne delivers measurable, durable improvements in cracking resistance, rutting resistance, fatigue performance, and structural capacity. Specify it — not 19mm.
   
   
2. A ≥20% increase in AASHTO Structural Number and a 3–5-year service life extension is confirmed in field evaluations across multiple Canadian jurisdictions.
   
   
3. ARCA is fully compatible with standard asphalt plant operations — no capital investment or mix redesign required.
   
   
4. The installed cost premium of $2–3/m² is recoverable through lifecycle cost reduction within the first intervention cycle for most asset classes.
   
   
5. For composite pavements (asphalt over concrete), HSAI at 130 g/t provides the high-strain crack dampening required — as demonstrated on NB Route 8.
   
   
6. Balanced Mix Design validation using IDEAL-CT and Hamburg Wheel Tracking is the correct QA protocol for ARCA and HSAI projects.

Presented at: Nova Scotia User Producer Association (NSUPA) Annual Conference, April 9, 2026 · Presenter: Michael J. Simons, P.Eng. · Contact: michael.simons@surface-tech.com · T: 647.613.6988 · Based on Simons, M.J. — ARCA in Canada, 2026. Surface Tech Construction Materials Corp. Confidential.