State DOT Curing Compound Specifications and Approved Lists

A DOT job does not care what the pail says. It cares what the state’s spec section says and whether your product, and sometimes your exact lot, is on the state’s list. Every state starts from the same base standard, then adds its own numbers and its own approval process.

What standard do state DOTs use for curing compound?

Almost all of them start from AASHTO M 148 or ASTM C309, which cover the same liquid membrane-forming compounds. FHWA’s paving curing guide puts it as “AASHTO M 148 (ASTM C 309) is the most commonly referenced specification for curing compounds for highway paving” (FHWA).

Which name the state cites varies. Iowa’s current Section 4105 opens with “Comply with ASTM C 309 and the following requirements” (Iowa DOT 4105). Paving products usually claim both. W.R. Meadows lists 1600-WHITE as ASTM C309 and AASHTO M 148 Type 2 Class A (W.R. Meadows).

The part that gets material rejected is what the state adds. FHWA notes that some states limit moisture loss to values lower than M 148’s 0.55 kg/m² at 72 hours. It also notes that ASTM C1315, at 0.40 kg/m² in 72 hours, “is not referenced in any current paving guidance found.”

Why do DOTs require white pigmented Type 2 compound on paving?

White pigment reflects sunlight, which is why Iowa and Indiana set a minimum reflectance, and it shows the inspector where you sprayed. FHWA says “White pigmented curing compounds are normally required when exposure to sunlight is anticipated,” and that white or fugitive dye compounds are required when the application has to be checked by eye.

Type 2 is the white pigmented type in the C309 family. South Carolina’s spec spells out the classes: Class A can be all resin or all wax based, and Class B is all resin based. Many states also name the resin.

Indiana and Wisconsin list wax-based white and poly-alpha-methylstyrene (PAMS) white separately. For how white compares with clear and dyed products off the highway, see clear vs dyed vs white curing compound.

How do state DOT curing compound specs compare?

The table covers only the documents read on November 8, 2026. Check the current edition for your state before bidding, since sections and lists change every year.

Sources: Iowa DOT 4105, MnDOT curing compounds, WisDOT approved batches, SCDOT supplemental spec, INDOT 912-M-055.

South Carolina is the clearest example of VOC limits written into a DOT spec. Wisconsin also asks for the VOC amount on the test report that goes with every sample.

How does a curing compound get on a DOT approved list?

There are two common models. Some states list products: the manufacturer qualifies the product once, then recertifies. Others list lots or batches: each batch is sampled and tested before it can go on a job.

• Product lists. South Carolina accepts material on its Qualified Product List 33 when the paperwork and labels are in order. Indiana adds products through its ITM 806 procedure, with testing by an NTPEP-approved lab, an annual recertification letter and a batch certification every four months.
• Lot or batch lists. Wisconsin lists each approved batch with its approval date and test number, from a one-quart sample sent with the manufacturer’s test report. Minnesota lists pre-approved lots with expiration dates. Iowa approves lots for the year they were made.

That is why a label claim is not enough. A product note for a white wax compound says it “meets state DOT specifications” without naming a state (Concrete Decor). Your inspector will check the list, not the pail.

What application rate does a DOT job need?

The rate lives in the paving or structures section, not always in the material section. The TxDOT pavement manual calls for “Type 2 membrane curing compound” in two separate coats, the first within 10 minutes and the second within 30 minutes after texturing. Each coat should be “not more than 180 ft.2/gal” (4.4 m²/L) (TxDOT).

FHWA reports that the AASHTO guide specification requires 3.5 m²/L, about 140 ft²/gal, applied by fully atomized spray. It adds that manufacturers typically recommend 5 to 10 m²/L, which is about 200 to 410 ft²/gal. So a DOT rate is often heavier than the number on the data sheet.

Plan to prove the rate. FHWA found no standard test for checking the rate in place, so it is estimated from the amount used over a known area. Log gallons and square yards for each pour. TxDOT also checks by eye: if water wets the surface instead of beading, or some areas are whiter than others, add coats.

If your curing compound is not on the approved list

Do not spray it and hope. Ask the project engineer which listed product or lot your supplier can get, since most states post the list online and update it during the season. On lot-list states, a new batch of the same product may need its own test before it counts.

If you already applied unlisted material, tell the engineer before the inspector finds it. The state decides whether to sample it, accept it with documentation or require something else. Keep the batch number, data sheet and the gallons and area for that pour so the conversation is about facts.

What paperwork does the inspector want?

South Carolina’s list is typical. For each project, you provide:

1. A certificate of analysis and performance test results for each lot or batch, showing it meets ASTM C309 for the type and class.
2. The safety data sheet.
3. The application instructions.

Containers must be marked with the manufacturer, batch number, type and class, and date of manufacture. Bulk tanker loads get a label on the project storage tank. Wisconsin’s sample paperwork adds total solids, drying time and VOC content. For writing these items into your own specs, use the specifier checklist for curing compounds.