Slurry Seal Calculator
Estimate pavement slurry seal mix quantities from area, application rate, aggregate gradation, emulsion, water, additive, density, truck capacity, and waste allowance.
Slurry seal material estimate
Results update when you change any input.
| Gradation | Typical dry rate | Texture target | Common use |
|---|---|---|---|
| Type I fine | 8-12 lb/yd2 | Fine, tight seal | Parking lots, low-volume streets |
| Type II general | 14-20 lb/yd2 | Medium texture | Residential and collector streets |
| Type III coarse | 18-30 lb/yd2 | Coarser skid texture | Arterials and rougher surfaces |
| Micro surfacing | 18-32 lb/yd2 | Polymer modified texture | Rut fill, higher traffic, fast return |
| Mix component | Typical design range | Calculator basis | Field check |
|---|---|---|---|
| Dry aggregate | 8-30 lb/yd2 | Area times spread rate | Box calibration and yield tickets |
| Asphalt emulsion | 8-20% of dry aggregate | Weight percent, then volume | Mix design and break behavior |
| Added water | 4-12% of dry aggregate | Weight percent, then volume | Workability and segregation |
| Additive | 0.25-2.0% of dry aggregate | Dry weight percent | Set time and compatibility |
| Waste factor | 5-15% | Multiplier on area and materials | Startup, overlap, handwork, cleanup |
| Truck capacity | Approx wet load | Best use | Planning note |
|---|---|---|---|
| 800 gal | Small batch | Patchwork and tight sites | Expect more staging cycles |
| 1,200 gal | Medium batch | Cul-de-sacs and parking bays | Good for short pulls |
| 2,000 gal | Production batch | Street sections | Common planning capacity |
| 3,000 gal | Large batch | Long pulls and yards | Check legal weight and access |
| Project condition | Recommended setting | Watch item | Adjustment idea |
|---|---|---|---|
| Oxidized but sound pavement | Type I or Type II | Absorption at startup | Add modest waste and verify yield |
| Moderate traffic street | Type II | Spread box uniformity | Use design rate from spec sheet |
| Rough or open surface | Type II high rate or Type III | Ravelling and void demand | Increase rate after test strip |
| High traffic or rut filling | Micro surfacing | Polymer set and traffic return | Follow agency mix design limits |
Slurry seal are used as a pavement preservation treatment. Slurry seal isnt a method that is used to rebuild roads or to fix deep problems with road surfaces. Instead, slurry seal is used to slow the oxidation of the pavement and to fill in the small voids that exist within the pavement.
Because slurry seal can perform these tasks, it can provide the pavement with several more year of use before it is necessary to apply another form of road treatment. Within the treatment with slurry seal, though, it is necessary for the road designer to make several decisions regarding the components of the treatment process. For instance, it is necessary to decide what type of aggregate should be used in the treatment, how much of each component should be used, the density of the slurry seal, the number of truck loads of slurry seal will be required to complete the job, and how much waste should be allowed during the treatment of the road.
How to Plan Slurry Seal for Roads
The first decision that must be made is regarding the gradation of the aggregate that will be used in the slurry seal. Type I gradations are among the finest gradations of aggregate, and are used if the pavement to be treated does not need to be textured. Type II gradations are of medium fine-ness, and are typically used for residential streets and collectors.
Type III gradations contain more stone than the other types of slurry seal, and are used in locations where the pavement will experience heavy traffic. Finally, micro surfacing is a type of treatment that contains a polymer that provides additional strength to the slurry seal and permits it to dry faster, which is beneficial for locations where the treated roads will need to accommodate traffic quick after treatment. Each type of aggregate has a typical rate at which it can be spread, which will allow the contractor to determine how much of the dry aggregate will be necessary for the areas of the road that will be treated.
Once the road designer chooses the aggregate gradation, the percentages of emulsion, water, and additives will need to be determined. The percentage of emulsion will determine how much asphalt will be present on the pavement after the water has evaporated. The percentage of water will determine how the mix will exit the spread box, as well as the workability of the treatment mixture.
Finally, the percentage of additives, typically cement or latex, will affect the setting time of the mixture. Each of these percentages is connected to the others, so altering one will impact the others. For instance, if the percentage of emulsion is increased, more asphalt will be added to the pavement, but less water will be needed.
These percentages can be calculated with a calculating tool that will convert the percentages to the weights of each component in gallons, and will calculate the number of truck loads that will be necessary to transport the amount of slurry seal needed for the project. Beyond calculating the percentages of each component needed, it is also necessary to decide the density of the slurry seal. The density of the slurry seal will impact the amount of material that will be added to the pavement, as slurry seal is placed by volume even though it is ordered by weight.
For instance, a wet slurry seal that weighs 118 lb per ft^3 will have a different application rate than a slurry seal that weighs 126 lb per ft^3. The density will impact the number of truck loads necessary for the project. The volume of the slurry seal that will be placed on the road will determine the number of truck loads, taking into account the capacity of the trucks to carry the slurry seal. Because the trucks will have limited capacity to carry the slurry seal due to the presence of the mixing paddles for the slurry seal and the need to provide a safety margin for the driver, it is not uncommon for the capacity of the trucks to not be a round number.
The calculating tool will determine how many truck loads will be necessary. Another decision that will impact the slurry seal treatment is the allowance for waste. Many road crews will find that there is waste in several steps of the slurry seal process.
For instance, some of the slurry seal may be wasted during the startup of the treatment process. Some waste may be created during the overlapping of different road sections by the joints in those sections. Some waste may be created during the handwork to avoid utilities on the road.
Finally, waste may be created in the cleaning of the spread box. Therefore, some waste allowance should of be made in the calculations for the slurry seal treatment. Five percent waste may be too little to provide for these wastes; ten percent waste allowance may be the minimum allowance for most road crews, and fifteen percent waste allowance may be the standard for small or irregular road sites.
The calculating tool will make allowances for waste before it calculates the total amount of slurry seal that will be required for the road. In addition to the parameters that are discussed above, there may be some differences between the textbook knowledge of slurry seal treatments and the actual application of such treatments on the job sites. For instance, the moisture that is present in the stockpiles of aggregate may differ every day.
The temperature of the pavement will also affect the rate at which the emulsion within the slurry seal will break down. Finally, a road may appear good to be treated in the office, but may reveal patches that are “raveled” when the spread box applies slurry seal to those patches. Due to these variables, it is best for the crews to perform a test strip of the slurry seal before they begin to apply the slurry seal to the remainder of the road with the full crew.
Based off the yield of the test strip, the crews will know if the spread box needs to be adjusted before the aggregate is even delivered to the site. In the treatment plan, there are tables that list the typical rates for each type of aggregate, as well as the percentages of emulsion and water that should be used for each type of aggregate. These tables dont need to be memorized, but it is important for the road crews to recognize if the conditions at the job site are outside of these tables.
If they are outside of the tables, the percentages will need to be shifted to account for these differences between the textbook and the job site. Within the design of the slurry seal treatment, it is necessary to determine the amount of asphalt in the slurry seal, which is referred to as the residual asphalt rate. This rate is important in that if there is too little asphalt in the slurry seal, the pavement may fail with time.
Too much asphalt in the treatment may cause the pavement to remain tender or to flush out of the pavement during hot weather conditions. Based upon the percentage of the emulsion and the amount of solids in the treatment, the residual asphalt rate can be calculated. Finally, the value of the slurry seal treatment plan is in the ability to revise that plan based upon the appearance of the test strip or the actual road temperatures at the treatment sites.
The calculating tool will prevent the road crews from having to perform the arithmetic for the components of the slurry seal treatment, but the crews must still be able to make small adjustments based upon the performance of the slurry seal on the test strip.
