285 All areas of soft or yielding subgrade, as shown on the plans, shall be corrected prior to pulverization operations.
307.07 Equipment The equipment shall be capable of pulverizing the existing asphalt pavement, base and subgrade materials. The equipment used for mixing the pulverized materials with 120
cement, water, additives, and corrective aggregate, when required, shall be capable of producing a homogenous and uniformly blended RBC. The equipment used for placement of the RBC shall be capable of placement in accordance with 105.03. The equipment shall consist of the following major components: (a) Spreaders and Distributors Spreaders or distributors used to apply dry powder additives shall be non- pressurized mechanical vane-feed, cyclone or screw type capable of providing a consistent, accurate and uniform distribution of material while mi nimizing dust during 130 construction. Corrective aggregate, when required, may be placed by a mechanical spreader, a conventional paver, or by tailgating with end dump trucks and spread to a uniform thickness with a motor grader.
b.Additive Slurry Storage and Supply Equipment Slurry shall be produced using a batch or continuous-flow type stationary mixer equipped with calibrated metering and feeding devices that introduce the cement, water and additives into the mixer in the specified quantities. Additive slurry storage and supply equipment shall have agitators or similar equipment to keep the slurry in suspension when held in the slurry batch or storage tanks. Slurry shall be kept in 140 suspension during transport using agitator equipment. (c) Mixing and Reclaiming Equipment Only self-propelled, high powered, minimum 500 hp rotary mixers or reclaimers capable of mixing in-place to the depth sp ecified shall be used. The minimum cutting drum width shall be 7 ft and fitted with cutting teeth capable of trimming earth, aggregate, and HMA and be designed to allow the cutting teeth to be accurately adjusted vertically and held in-place. Th e machine shall have a minimum weigh of 25,000 lb, and shall have the strength and rigi dity to allow a center deflection of not more than 1/8 in. 150 The mixer or reclaimer shall be fitted with an integrated water injection system capable of introducing the water into the cutting drum during the mixing process. The metering device shall be capable of automatically adjusting the flow of material to compensate for any variation in the amount of reclaimed material introduced into the mixing chamber. The water shall be calculate d on a volumetric basis tied to a speed gauge, ft/min, using a calibrated meter that is capable of accura tely measuring the amount of material to within 0.5% of the rate required. Automatic digital readings shall be displayed for both the flow rate and total amount of reclaimed material in appropriate units of weight and time. 160 307.07 286 (d) Motor Grader A motor grader for pre-shaping, aerating, spreading, and final shaping of the material shall be utilized. The motor grader shall have a cross slope indicator.
e.Compaction Equipment The RBC shall be compacted using self-propelled rollers. The number, weight, and types of rollers shall be as necessary to obtain the required compaction throughout the entire RBC thickness. The rollers may be used in any combination and may include a pneumatic tire roller, an 84 in. wide drum vibratory pad-foot roller equipped with a 170 knockdown blade, or a 10 t minimum single or double drum vibratory steel roller.
f.Water Trucks A water truck shall be used for supplying water to the reclaimer or roadway for the addition of moisture during the reclaiming operation. The water truck shall be capable of providing a controlled and consistent spray without eroding or otherwise damaging the compacted RBC. 307.08 Weather Limitations FDR operations shall be performed when the ambient temperature is 40°F or 180 above. The FDR shall not be performed when the soil, aggregate, or subgrade is frozen or when freezing temperatures are anticipat ed within seven days of the end of RBC placement. The Engineer may restrict work wh en the heat index is greater than 100°F. The FDR shall not be performed before May 1 or after October 1. 307.09 Pulverization The existing pavement shall be pulverized and stabilized in separate operations. Corrective aggregate, when required, sha ll be spread onto the existing surface in accordance with 307.07(a). The pre-determined full depth of asphalt pavement, base, and subgrade materials shall be pulverized, along with the corrective aggregate, to a 190 homogenous mixture. The mixture may be br ought to the desired moisture content during this process by means of surface application or through the mixing or reclaiming equipment’s integrated fluid injection system for dust control. The base course shall not contain roots, sod, topsoil, weeds, wood, or any material deleterious to its reaction with the cement stabilizer. For cement stabilized RBC, the pulverization shall produce a gradation that has SDVVLQJWKHLQ PP VLHYHDQGSDVVLQJWKH1R PP VLHYH When a paving fabric is encountered during the pulverization operation, the 200 Contractor shall make the necessary changes in equipment or operations so that incorporation of shredded fabric into the RBC does not affect the performance parameters or inhibit placement or compac tion of the RBC. The Contractor shall remove and properly dispose of oversized pieces of paving fabric. The Contractor shall make the necessary adjustments in equipment or operations so that the shredded fabric in the recycled material is no more than 5 sq in. No fabric piece shall have a dimension exceeding a length of 4 in. 307.08 Rubberized crack filler, durable pavement markings, loop wi res, and other non- pavement materials shall be removed fr om the roadway during the pulverization 210 process. Residual materials that cannot be completely removed may be incorporated into the mixture if the Contractor can demonstrate that those added materials will not adversely affect performance. Any such materials retained in the mixture shall be appropriately sized and blended so as to not adversely affect the strength of the RBC.
307.10 Stabilization The cement used to stab ilize the RBC may be dry powder or slurry. The
Contractor shall address the application methods and fugitive dust control procedures 220 in the QCP when dry powder materials are used. The pulverized surface shall be scarified or knifed prior to applying materials in slurry form to prevent runoff or ponding. Any dry additives used shall be spread onto the pulverized surface using a mechanical spreader. The pulv erized material shall be mi xed with the stabilizer and additives, as required by the mix design, to create a homogeneous RBC. The in-place moisture content of the material shall be within -1% to +2% of the design moisture content as determined by the mix design. Cement stabilizing materials shall have an application tolerance determined by 230 adding ±0.5% to the percent total cement content. The cement shall be incorporated into the pulverized material at the initial rate shown in the approved mix design. Sampling and mix design may determine different levels of cement at various portions of the project. The Contractor can request the cement percentage to exceed the upper tolerance provided the mix design requirements are satisfied at the requested percentage. The request will be subject to approval by the Engineer.
307.11 Control Strip and Compaction A minimum 500 ft long control strip shall be constructed on the first day of production to verify the construction process meets the requirements as specified. The control strip shall allow the Contractor to:
a.demonstrate that the equipment, materials and processes proposed can produce an RBC layer in accordance with specification requirements;
b.determine the optimal rates for the cement, water, and any additives 250 recommended for the reclaimed material;
c.determine the sequence and manner of rolling necessary to obtain strength requirements in one uniformly compacted layer. 307.11 The RBC density shall be achieved with the same equipment, materials, construction methods, and dens ity requirements used on the accepted control strip. A new control strip shall be constructed if cha nges are made outside the tolerances of the original mix design, equipment, or construction methods. 260 The processed material shall be uniformly compacted in one layer to a minimum of 95% of the maximum density. Maximum density shall be determined in accordance with AASHTO T 180 at the required QC frequency from a representative sample collected after the cement has been added and mixed into the pulverized material but prior to compaction. Compaction shall be monitored in accordance with AASHTO T 310 in the direct transmission mode and continue to reach a minimum of 95% of the established maximum density during the control strip and for the remainder of the compaction operation. 270 Compaction equipment shall be in acc ordance with 307.07(e). Initial compaction shall be within 500 ft of the reclaiming unit using either a vibratory pad-foot roller, a pneumatic tire roller or a combination of the two. The pass counts shall continue to increase until the cleat indentations from the pad-foot roller are no more than 3/16 in. in depth and light can be seen between the pad-foot and RBC interface or there are no wheel impressions from the pneumatic tire roller remaining in the RBC. The cement stabilized material shall be bladed and shaped by a motor grader in accordance with 307.07(d) to remove any rema ining roller marks or indentations then 280 leveled in accordance with 301.07. The pr ofile grade and cross-section of the RBC shall be finished within a tolerance of ±1/2 in. from the plan RBC elevation prior to profile milling. Intermediate and final compaction shall be applied to the bladed and shaped RBC using either a pneumatic tire roller, a single or double drum vibratory steel roller, or a combination of the two. Finish rolling shall not be performed in vibratory mode. The compaction operation shall be performed while the RBC remains in a workable condition and continued until roller marks no longer appear. 290 Any type of rolling effort that causes cracking, displacement, or other type of pavement distress shall be discontinued until such time as the problem can be resolved as approved by the Engineer. The QC technician shall be on site, observing all compaction efforts and approving areas as they reach minimum rela tive compaction. Care shall be taken to not over compact the mat. All tests shall be conducted at the stated QC testing frequencies throughout FDR operations. 300 307.11 289 307.12 Maintenance The Contractor shall maintain the RBC until the surface course has been constructed. Any damage to the completed recycled material shall be repaired by the Contractor prior to the placement of new HMA or final surface sealing. Patching shall be in accordance with 304. The excavated patch areas shall be filled and compacted with HMA or RBC material as directed by the Engineer. No payment will be made for damage or repair unless approved by the Engineer. 310
307.13 Curing
The planned method and duration of curing for cement stabilized RBC shall be in accordance with the QCP. The specified surface course shall be placed within two weeks of the RBC final cure, but no later than November 1. Before placing the final surfacing, th e cement stabilized RB C shall remain in- place for a minimum of three days. Cement stabilized RBC shall be cured to minimize moisture loss from the surface 320 for a time period that achieves the minimum required 7-day unconfined strength.
307.14 Proofrolling The cement stabilized RBC shall be proo frolled in accordance with 203.26 using
a tandem or tri-axle dump truck loaded to the legal limit. The Engineer will determine the corrective remediation limits for any area that has deflection or rutting greater than 1/2 in. The Contractor shall rework the areas that fail in proofrolling by re-pulverizing and re-stabilizing the RBC in-place at no additional cost or by removing the RBC and 330 stabilizing the subgrade with subgrade treat ment Type IC in accordance with 207. In locations of failing subgrade, the RB C shall be removed and subgrade treatment Type IC shall be placed in accordance with 207. HMA patching, Type B shall be placed in accordance with 304 in place of the RBC.
307.15 Milling
The entire surface of the cement stabilized RBC shall be scarified in accordance with 306.04 in preparation for the overlay. Liquidated damages will not apply. Construction engineering in accordance with 105.08(b) shall be provided. 340
307.16 Underdrain Installation Underdrain installation in accordance with 718, when required, shall begin after
proofrolling has been completed.
307.17 RBC Overlay
The overlay atop the RBC shall be as shown on the plans. The overlay shall be placed after proofrolling has been completed. 307.17 The RBC shall be swept of all loose material and standing water with a rotary 350 power broom in accordance with 409 immedi ately prior to placing the surface. The RBC shall be swept lightly to avoid damage to the RBC. A tack coat shall be required only for the HMA overlay and shall be applied to the RBC, in accordance with 406, immediately following sweeping operations. Monuments shall be reestablished in accordance with 615.10.
307.18 Opening to Traffic Opening to traffic shall occur after suff icient cure time in accordance with 307.13 360
has been applied to the RBC so traffic will not initiate raveling or permanent deformation. All loose particles that ma y develop on the pavement surface shall be removed by a rotary power broom in accordance with 409. After opening to traffic, the surface of th e RBC shall be maintained for the safe movement of traffic. 307.19 Method of Measurement The RBC will be measured by the square yard, complete in place. Cement, used as stabilizing material, will be measured by the ton. Subgrade treatment will be 370 measured in accordance with 207.05. Co rrective aggregate to adjust the RBC gradation will be measured by the ton of material used. HMA patching, Type B will be measured in accordance with 304.06. Milling will be measured in accordance with
306.10 Re-established monuments will be measured in accordance with 615.13.
Removal of snowplowable raised pavement markers will be measured in accordance with 808.12. 307.20 Basis of Payment The RBC will be paid for as full depth r eclamation at the contract unit price per square yard, complete in place. Cement, used as stabilizing material, will be paid for 380 at the contract unit price per ton, complete in place. Subgrade treatment will be paid for in accordance with 207.06. Corrective aggr egate used to adjust the RBC gradation will be paid for at the contract unit price per ton, complete in place. HMA patching, Type B will be paid for in accordance with 304.07, for the thickness shown on the plans. Milling will be paid for in accordance with 306.11. Re-established monuments will be paid for in accordance with 615.14. Removal of snowplowable raised pavement markers will be paid for in accordance with 808.13. Payment will be made under: Pay Item Pay Unit Symbol Corrective Aggregate, FDR ....................................................... TON Full Depth Reclamation ............................................................. SYS Stabilizing Material, Portland Cement ...................................... TON 307.18 The costs of the FDR mix design and QC testing shall be included in the cost of the full depth reclamation. The costs associated with removal of gr ass and vegetation, rubberized crack filler, 400 durable pavement markings, loop wires and other non-pavement materials shall be included in the cost of the full depth reclamation. The costs associated with pulverizing, stabilizing, compacting, curing, and maintenance of the RBC shall be included in the cost of the full depth reclamation. The cost associated with mixing water shall be included in the cost of the full depth reclamation. The cost associated with aggregate, wh en used to supplement material volume, 410 shall be included in the cost of the corrective aggregate pay item. The cost associated with ag gregate, when used to adju st the RBC gradation, shall be included in the cost of th e corrective aggregate pay item. In the locations of failing subgrade, removal of the RBC shall be included in the cost of subgrade treatment.
Source: Indiana Standard Specifications, 2024 Edition. Pages 299–306 of 1,248.