SS248-002020-02.docx
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- Attached to
- Construction, University Drive Bike Lanes
- Solicitation number
- IFB-114424
- Issued by
- Fairfax County, Virginia
About this file
This is a supplemental specification document issued by the Virginia Department of Transportation (VDOT) on March 18, 2024, establishing guidelines for Stone Matrix Asphalt (SMA) concrete projects. The specifications detail material requirements, composition standards, and acceptance criteria for SMA mixtures used in road and bridge construction. Key technical requirements include mandatory use of antistripping additives in all SMA mixes at minimum rates of 0.30 percent by weight of asphalt content, with options for hydrated lime or approved chemical additives. The document establishes design ranges for three SMA types—SMA 12.5, SMA 9.5, and SMA 19.0—with specific gradation requirements across various sieve sizes. Contractors are required to perform flat and elongated particle (F&E) testing on coarse aggregates according to VTM-121 standards, with initial testing on two of eight sub-lots from the first production lot and subsequent testing on alternating lots if initial results pass.
Acceptance criteria require contractors to monitor volumetric characteristics of asphalt (VCA) for each gyratory sample and maintain conformance with approved job-mix formulas and Table II-25 specifications. Contractors must immediately notify the Engineer and implement corrective action if VCA equals or exceeds design reference criteria, with production stoppage and removal of non-conforming material at contractor expense if VCA exceeds limits. The specification also mandates visual inspection of finished pavement for uniformity and surface quality, with the Engineer determining acceptability when irregularities such as segregation, rutting, raveling, or flushing are detected. Any revised or unverified job-mix formulas are limited to test runs of 300 tons maximum before full approval is granted by the Engineer.
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Guidelines: All Projects.
SS248-002020-02 March 18, 2024
VIRGINIA DEPARTEMENT OF TRANSPORTATION
2020 ROAD AND BRIDGE SUPPLEMENTAL SPECIFICATIONS
SECTION 248 – STONE MATRIX ASPHALT CONCRETE
SECTION 248 – STONE MATRIX ASPHALT CONCRETE of the Specifications is amended as follows:
248.02 – Materials (f) is amended by replacing the first paragraph with the following:
Antistripping Additive: An antistripping additive shall be used in all stone matrix asphalt mixes. It may be hydrated lime or a chemical additive from the Materials Division’s Approved List No. 7, or a combination of both. When an approved chemical additive is used, it shall be added at a rate of not less than 0.30 percent by weight of the total asphaltcontent of the mixture unless otherwise indicated on the Department’s Approved List No. 7.
248.03 – Composition of SMA Mixtureis amended as follows:
TABLE II-24 is replaced with the following:
TABLE II-24
SMA Design Range
Type No.
(See Note) Percentage by Weight Passing Square Mesh Sieves (in)
| 1 |
| 3/4 |
| 1/2 |
| 3/8 |
| No. 4 |
| No. 8 |
| No. 30 |
| No. 200 |
Surface Mixes
SMA 12.5
| 100 |
| 83-93 |
| 80 max |
| 22-27 |
| 16-24 |
| 14-20 |
| 9-11 |
SMA 9.5
| 100 |
| 90-100 |
| 65-75 |
| 25-32 |
| 15-25 |
9-11
Intermediate Mixes
| SMA 19.0 |
| 100 |
| 85-95 |
| 50-60 |
| 30-45 |
| 16-24 |
| 12-16 |
| 8-10 |
Note: The required PG binder will be shown in parentheses as part of the mix type on the plans or in the proposal, e.g., SMA 12.5 (64E-22).
Section 248.04—Acceptance is amended by replacing the third, fourth, fifth, and sixth paragraphs with the following:
The Contractor shall check and report the percentage of flat and elongated particles (F&E) in the coarse aggregates of the mix design during production. Two of eight sub-lots from the first lot of material shall be selected for F&E verification when the Contractor samples the SMA material for acceptance (gradation and AC content). F&E testing shall be performed in accordance with VTM-121, after the gradation is performed. If passing results are obtained on each sample in the first lot, then F&E testing shall be performed on a frequency of every second lot of material produced (i.e., Lots 3, 5, 7, etc.) by randomly selecting two sub-lots. If the F&E of the mix exceeds the specified limits, the Contractor shall stop production and notify the Engineer. Production shall not resume until the Contractor has taken corrective action and the Engineer has accepted the Contractor’s means of correction. Once production has resumed, the Contractor shall determine the F&E of the mix for two consecutive lots by randomly selecting two sub-lots per lot. If passing results are obtained for these two lots, then the F&E testing frequency shall return to every second lot of material produced.
The Contractor shall check and report the VCA of the mix during production for each gyratory sample. If the VCA of the mix equals the VCA of the DRC, the Contractor shall immediately notify the Engineer, document the JMF changes in the Producer Lab Analysis and Information Details (PLAID) website, and provide corrective action. If the VCA of the mix exceeds the VCA of the DRC, the Contractor shall stop production, notify the Engineer, and remove and replace that day’s production at no cost to the Department. Production shall not resume until the Contractor has taken corrective action and the Engineer has accepted the Contractor’s means of correction.
If the Department determines that the mixture being produced does not conform to the approved job-mix formula or the volumetric properties in Table II-25, based on the Department or the Contractor’s test results, the Contractor shall immediately make corrections to bring the mixture into conformance with the approved job-mix formula and Table II-25 or cease paving with that mixture. The Engineer will investigate and determine the acceptability of the mix placed since the previous passing sample.
The finished pavement shall be uniform, free of irregularities and smooth. If irregularities including segregation, rutting, raveling, flushing, fat spots, mat slippage,irregular color, irregular texture, roller marks, tears, gouges, streaks,uncoated aggregate particles, or broken aggregate particles are detected, the Contractor shall immediately notify the Engineer and address the determined irregularities with corrective action. When irregularities are noted, the acceptability of the finished mat shall be determined by the Engineer.
The Engineer will limit subsequent paving operations using either a revised or another job-mix formula, which has not been verified as described herein, to a test run of 300 tons maximum if such material is to be placed in Department project work. The Engineer will not allow any further paving for the Department using that revised mixture until the acceptability of that mixture has received the Engineer’s approval based on the 300-ton constraint.
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