NCAT Test Track Case Study
VDOT S12/N4 NCAT Test Track: Elastiko® ECR Delivers Measurable Mix Performance
NCAT data shows the VDOT S12-GTR mix with Elastiko® Engineered Crumb Rubber exceeded reported BMD thresholds and showed no cracking at 1.8 MESALs. This is performance proof for a dry-process asphalt mix modifier evaluated at the mixture level.
Agency / Sponsor
Virginia Department of Transportation.
Product
Elastiko® Engineered Crumb Rubber.
Material Type
Dry-process GTR / asphalt mix modifier.
Mix Type
VDOT 12.5 NMAS dense-graded asphalt.
Test Sections
S12-GTR and N4-SBS.
Field Performance Summary
No cracking reported at 1.8 MESALs.
The Mix Design Behind the Performance
The NCAT update documents the mix design, production data, and early field performance behind the S12-GTR section. The key takeaway: Elastiko® ECR was evaluated in the mix, met reported performance thresholds, and showed no cracking at 1.8 MESALs.
ECR Dosage
The S12-GTR section used 12% Elastiko® ECR by weight of virgin binder as a dosage basis. Elastiko® ECR is a mix modifier, not a binder modifier.
Production / Placement Date
Production and placement took place August 23/24, 2024.
Dry-Process GTR Mix Design
The S12-GTR mix used PG 64-22 plus 12% Elastiko® ECR by weight of virgin binder. The GTR mix included 5.5% AC, with an extra 0.2% to account for binder absorption. The performance was evaluated through mixture-level testing, not binder modification claims.
Performance Proof
At 1.8 MESALs, the NCAT update reports no cracking in the field performance summary. The same update documents early rutting performance and IRI data for the N4 and S12 sections, giving agencies and producers a field-performance view of the S12-GTR mix under NCAT Test Track loading.
Cracking Performance
At 1.8 MESALs, the NCAT update reports no cracking in the field performance summary.
Rutting and IRI
The report includes early rutting performance and IRI data for the N4 and S12 sections, supporting a mixture-level view of field performance.
The Proof Point
The VDOT S12-GTR production mix reported an IDEAL-CT CTIndex of 124.8 against a stated threshold of 70, while the mix design CTIndex was 94.9 against that same threshold. At 1.8 MESALs, the NCAT update reports no cracking in the field performance summary.
Performance Details
Key NCAT Data Points
The key numbers show why this NCAT update matters: documented mix design, production results, BMD thresholds, and early field performance for a dry-process ECR mix modifier.
Mix Type
VDOT 12.5 NMAS DGA.
Aggregate Blend
Traprock 78s: 39%; 10s: 46%; RAP: 15%.
Control Mix
N4-SBS, PG 76-22.
GTR Mix
S12-GTR, PG 64-22 + 12% Elastiko® ECR.
Production GTR CTIndex
124.8 against a stated threshold of >= 70.
Cracking Performance at 1.8 MESALs
No cracking reported.
From Design to Proof
The Challenge, the ECR Mix, and the Results
Challenge
VDOT and NCAT evaluated whether a dense-graded asphalt mixture using dry GTR could deliver measurable performance under NCAT Test Track conditions. The study compared section performance through mix design, production QC, BMD results, and early field performance.
Solution
The S12-GTR mix used PG 64-22 plus 12% Elastiko® ECR by weight of virgin binder. The GTR mix included 5.5% AC, with an extra 0.2% to account for binder absorption. The performance was evaluated through mixture-level testing, not binder modification claims. The pavement structure included 6 inches of aggregate base, 4.5 inches of CCPR, and 2.8 inches of DGA.
What the Results Prove
The NCAT update shows the S12-GTR mix did more than meet the stated BMD cracking threshold. The mix design CTIndex was 94.9 against a threshold of 70, and production mix data reported a GTR CTIndex of 124.8 against that same threshold. At 1.8 MESALs, the report states that no cracking was observed.
Why This Study Matters
Why This Study Matters
The VDOT S12/N4 study matters because it gives agencies and producers a fact-based look at how Elastiko® ECR performs in a dense-graded asphalt mix under NCAT Test Track conditions. The study connects mix design, production QC, BMD results, and field performance, showing how dry-process ECR should be evaluated: at the asphalt mixture level.
Next Steps
See the VDOT S12/N4 NCAT Performance Data
Review the NCAT data behind the S12-GTR section, including mix design, production QC, BMD results, and early field performance through 1.8 MESALs.
Read the Full VDOT S12/N4 NCAT Summary
See the exact NCAT-reported details behind the S12-GTR mix design, production results, BMD performance, and no-cracking field update at 1.8 MESALs.
Read the Full ReportView our Case Studies
Review additional Asphalt Plus case studies showing how Elastiko® ECR is used in real asphalt mixtures, field projects, and performance-focused applications.
View Case StudiesBrief Summary
The VDOT S12/N4 NCAT update documents Elastiko® ECR as a dry-process asphalt mix modifier used in a VDOT 12.5 NMAS DGA mix. The reported data shows CTIndex results above stated thresholds and no cracking observed at 1.8 MESALs.
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