Road Base Stabilizer Products Application

Control Strip

• If required, a control strip should be placed at the beginning of the project to evaluate the equipment, construction methodology, workmanship and to verify that the construction process meets specification requirements

Application of Dry Stabilizing Agents

• If added at a central plant verify application rates using meter on plant
• If adding new base material on site apply granular materials prior to mixing using a mechanical spreader, paver or by haul trucks and then spread to a uniform thickness with a motor grader
• Dry chemical stabilizing agents can be added prior to the mixing pass of the reclaimer. 
• Dry chemical stabilizing agents should be applied with non-pressurized mechanical vane-feed, cyclone or screw type bulk spreaders/distributors
• Check application rates either volumetrically or by using a “canvas patch” test or similar procedure  

Application of Stabilizing Agents Applied as Slurry

• Verify application rates of chemical stabilizing agents applied as slurry at a central plant using meter on plant
• Chemical stabilizing agents applied as slurry can be spread ahead of mixing passes using a calibrated liquid distributor or added during the mixing pass of the reclaimer using the reclaimer’s on-board additive system. Application through the reclaimer generally results in a more uniform application 
• Verify application of slurry stabilizing agents using the consumption of stabilizing agent (and water) obtained from the computer that controls the slurry mixing unit.

Application of Bituminous Stabilizing Agents

• Verify application rates of bituminous stabilizing agents mixed at a central plant using meter on plant
• Bituminous stabilizing agents applied during the mixing pass of the reclaimer using the reclaimer’s on-board additive system. 
• Verify the application rate by evaluating the mass of stabilized material against the volume of stabilizing agent used for a single tanker.
• For foamed asphalt stabilization, check the temperature of the asphalt before connecting a tanker to the reclaimer.
• For foamed asphalt stabilization, verify the expansion ratio and half-life using the test nozzle on the reclaimer.

In-place Mixing

• Check depth of mixing by removing the stabilized material on each side of the reclaimer and checking the depth.  
• Overlap longitudinal joints a minimum of 6 inches and transverse joints a minimum of 2 feet 

Compaction

• Establish a rolling pattern to achieve the required percent compaction
• Compact the stabilized material to the required percent compaction using any combination of segmented padfoot, vibratory padfoot, rubber-tired, vibratory single or double drum rollers 
• Compaction requirements for Bituminous stabilization are typically based on 95% of the maximum dry density determined in accordance with AASHTO T 180 or ASTM D1557, modified Proctor
• The total time for mixing, placing and compacting cementitious stabilized mixtures should be less than 2 hours
• Compaction requirements for Cement stabilization are typically 95 to 98% of ASTM D588.
• Stabilization with hydrated lime or LKD is usually allowed to mellow prior to compaction
• For stabilization with quicklime, the materials are usually allowed to mellow for at least 12 hours after mixing and prior to compaction
• Compaction requirements for Lime/LKD stabilization are typically based on standard Proctor, 95% of the maximum dry density
• Check compaction with a nuclear gauge, sand cone or other approved method
• Check cross-slope after final rolling 

Curing

• Stabilized materials need to be properly cured to achieve ultimate strength, prevent raveling and facilitate placement of the surface course
• Minimize vehicular traffic on stabilized materials for 30 to 60 minutes 
• Limit truck traffic until the stabilized material until the mix has cured sufficiently to support the anticipated traffic without damaging the stabilized mixture
• For chemical stabilizing agents either keep the surface moist or apply a curing membrane to allow proper hydration and strength gain of the materials, typically 2-7 days

Surface Course

• A surface course is required over stabilized materials
• Prior to placing the subsequent course sweep the stabilized mixture with a power broom. A fog or tack coat of emulsified asphalt may be required, depending on local practice.