In-Place Recycling Specification

Transcription

1 In-Place Recycling Specification Dallas Roadway Products, Inc Dallas Parkway, Suite 300 Addison, TX Phone: Copyrighted 2004 Dallas Roadway Products, Inc.

2 Section- Chemical Stabilized, In-Place Recycling 1. Description. 1.1 This work shall consist of conducting in-place recycling for road base- course using a combination of in-place or imported aggregates and a chemical stabilizer, uniformly mixed, moistened, compacted, shaped, and prepared for a either an unsurfaced or flexible asphalt-concrete (AC) wearing surface. Unless otherwise specified in the Contract Documents, the recycled base and chemical stabilizer agents will be roadmixed via a traveling, pulverized-mixer. A surface wearing course may be added to the treated aggregate road base in order to extend the life and reduce long-term maintenance of the roadways. 1.2 Benefits of In-Place Recycling: Cuts reconstruction time and cost Eliminates hauling out of old materials and hauling in new materials Saves Natural Resources 2. Materials. 2.1 In- Place Recycling Stabilizer/Chemical Treatment: Dallas Roadway Products (DRP) chemical stabilizers SA-44 plus LS-40 mixed in combination, or equal products, is recommended for stabilized base with In-Place Recycling Process. Dilution rate is indicated for DRP chemical stabilizer combination shall be at least 1 gallon of the chemical road base stabilizer LS-40 and 1 gallon of the chemical road base-stabilizer SA-44 to 200 parts of water Recommended Aggregate Types: a. Aggregate Type. All aggregate to be stabilized shall be either a lime/calcareous or Sodium Montmorillonite based aggregate, or a lime/calcareous or sodium montmorillonite based aggregate /clayey soil mixture, and shall conform to a specified maximum dry density and optimum moisture content of the material. The specified maximum dry density and optimum moisture content shall be determined as specified by AASHTO T-180, Method C, unless the material has more than 35% retained on the No. 4 sieve, in which Method D shall be used. Material with a maximum dry density of less than 100 lb. / cu. Ft. is unsatisfactory and shall not be used in embankments. b. Water. Water shall conform to the ph requirements of AASHTO T-26, Method B and shall be clear. 2 Copyrighted 2004 Dallas Roadway Products, Inc.

3 3. Construction. 3.1 The contractor shall protect the treated base against damage from all causes. Any part of the sub grad, subbase, or base that is damaged shall be repaired or replaced by and at the contractor s expense in a manner acceptable to the Engineer. 4. Equipment. 4.1 All equipment, including on site equipment, shall be subject to approval by the Engineer. 5. Weather. 5.1 Temperature and Surface Conditions. Chemical soil/ road base- stabilization operations shall only be conducted when the ambient air and surface temperature is at least 40 degrees Fahrenheit and rising. No material shall be mixed and /or compacted against frozen sub grade or sub base 5.2 Cold Weather Protection. When exposed directly to the elements, the completed in place recycled base shall be protected from freezing for a period up to the 14 th day following the application of chemical soil / stabilizer-stabilizer. 5.3 When road base surface temperatures below 40 degrees Fahrenheit are forecasted steps should be taken to p lace the base material (or next scheduled course) as a way of insulating the just treated and compacted sub grade / sub base layer 5.4 Precipitation. Construction shall not take place during periods of precipitation. When precipitation has occurred during the previous 24 hours, the Engineer will determine if the sub grade/ sub base is sufficiently dry to proceed. If precipitation occurs during actual construction operations, the operation then underway may continue but at the contractor s risk. 6. Scarification. 6.1 Interfaces of in-place, pre- existing, structural aggregate layers will be scarified to a depth of 6 to 8 inches. Chemical soil/ stabilizer-stabilizer will be applied to the scarified material followed by pulverize mixing to ensure maximum surface wetting of the previously applied chemical soil/ road base stabilizer. Scarification will extend to a distance 18 in. beyond the perimeter of paving as a way of ensuring maximum foundation support of the final wearing surface. Extending the stabilization 18 in. beyond the exposed pavement edges will also serve to reduce shrinkage effects during extended dry period and minimize pavement edge raveling. 3 Copyrighted 2004 Dallas Roadway Products, Inc.

4 7. Sub grade Preparation. 7.1 The approved sub grade/ sub bases should be set to final line and grade shall be completed (i.e., scarified, treated, mixed, compacted, and inspected for proper compaction) at lease 900 feet (dual-lane, or 1,800 lane-feet of single lane) ahead of the placement of the next lift of material to be placed, treated (as applicable), mixed in-lace (as applicable), and compacted. If traffic, including construction equipment, is allowed to use the sub grade/ sub base foundation or preceding /succeeding layer(s), traffic shall be distributed over the entire width of the course to aid in obtaining uniform and thorough compaction. If ruts are formed, ruts shall be removed by reshaping, applying additional soil/ stabilizer-stabilizer (as appropriate), and recompacting the affected area(s). Material one (1) to two (2) feet below the top of the sub grade/ subbase shall be compacted to not less than 92% of the maximum dry density as specified in AASHTO T-180. Material in the top one (1) foot below the top of the subgrade/ subbase shall be compacted to not less than 97% of the maximum dry density. 8. Design Mix. 8.1 At least 5 days before the start of constructing the area(s) to be treated with chemical soil/ roadbase-stabilzer, the Contractor shall submit to the Engineer samples of the aggregate stabilizers from the manufacturer along with appropriate material specifications, Technical Data Sheets, and mixing and application instructions. Based on materials tests and the soil/ stabilizer-stabilizer compatibility requirements by soil classification, test sample specimens will be prepared to ensure that the mix design is adequate for the site condition(s). Materials shall be sampled and tested in accordance with the local Construction and Material Specifications. 8.2 The Contractor shall provide testing to determine the exact proportions of aggregate mix and chemical stabilizers, and the optimum moisture content based on these samples. Proportions may be revised during construction to provide for changing conditions but only as directed and approved by the Engineer. Mixed-in place material (via pulveriser-mixer or windrowing) shall be sampled from a 100 ft. long control strip constructed on the site by the contractor. The Engineer shall inspect and approve the results of the control strip application test, the adjusted results of which shall constitute the final mix design for the project. 8.3 Dilution of the chemical soil/ roadbase-stabilzer shall be in accordance with instructions provided by the manufacturer, and shall be at least 1 gallon of the chemical roadbase - stabilzer LS-40 and 1 gallon of the chemica roadbase-stabilzer SA-44 to 200 parts of water. 9. Mixed In-Place Construction. 4 Copyrighted 2004 Dallas Roadway Products, Inc.

5 9.1 The goal is to thoroughly wet all of the recycled base particles being treated with chemical soil/ road base stabilizer during the pulverize-mixing step to a predetermined moisture content. When this has been accomplished and the moisture content is at the predetermined optimum moisture content (+/- 1%), the material is ready for compaction to the specified maximum compaction density. The in-place material shall be pulverized with a traveling pug mill to ensure that at the completion of in-place mixing, diluted aggregate/ stabilizer is uniformly and thoroughly distributed over the total mass of material to be treated and to ensure maximum effective compaction. Diluted chemical aggregate / LS-40 stabilizer-sa-44 stabilizer, shall be distributed via water-distributor vehicle over a manageable section of roadway, generally not to exceed 900 feet of two lane or 1,800 lane feet of single-lane roadway. The contractor will determine the extent of working sections within the limits prescribed. Stabilization will be extended 18 inches beyond the perimeter of paving as a way of ensuring maximum foundation support for the final wearing surface and to reduce shrinkage effects during extended dry periods. 9.2 Compaction is to be applied from the bottom up on the desired lift, while maintaining optimum moisture content for maximum compaction. Pneumatic tire roller equipment is recommended to be used to obtain a minimum of 98% of maximum dry density compaction, at or above, 2% of the aggregate s optimum moisture content. If the base material, becomes still or dry before the required maximum compaction is obtained, apply untreated water lightly and evenly, and complete the compaction operation. If the road base material is too wet to obtain the desired maximum compaction, reduce the material s moisture by aerating the soil/road base material to promote evaporation down to the required moisture content after stabilizer application and before compaction. 9.3 Road Construction Projects will likely involve at least the following steps : 1. Removal of 8 to 10 inches of material below the proposed finished grade elevation. Material at the elevation should be inspected and approved for use by the Engineer before proceeding with steps 2 to 5 below. 2. Pulverization of in-place calcareous and/.or sodium montmorillonite based aggregates with a traveling pug mixer. 3. Addition of diluted chemical stabilizer mixture (1 gallon SA-44 chemical and 1 gallon LS-40 chemical aggregate stabilizer to 200 parts of water) to the scarified aggregate in order to achieve a mixture at optimum moisture content plus 1%. 4. Mixing of the chemically treated aggregate with a traveling pug mixer while maintaining a uniform moisture content at, or not to exceed, optimum moisture content plus 1%. 5 Copyrighted 2004 Dallas Roadway Products, Inc.

6 5. Compaction of the chemically treated aggregate material to 98% of the aggregates maximum dry density at a uniform moisture content at, or not to exceed, optimum moisture content plus 1% as determined by AASHTO T Recommendations for Reclaiming Deteriorated Roadways Incorporate old asphalt and old base materials together by mixing 8 inches depth using a milling machine or reclaimer. Add 2% lime by weight and SA-44/LS-40 as recommended by company. Mix and Blend all materials together. Keep Mixing and adding water to get gradations and mixture of materials just under optimum moisture. Start compacting with material, using a compactor that will insure 8-inch compaction. Blade and shape road to grade elevation. Compactor can be removed when 6 inches to 7 inches has reached desired density. Keep grading and rolling until grad elevation and density has met requirements. Provided all has gone well and road has reached its desired density. 9.5 When finishing the base, it should be pointed out that normal vehicular traffic will continue to compact the road during cure time. 9.6 In the event the road cannot be completely compacted in one day, final surface shaping of the treated recycled base can be completed and the next day by adding untreated water lightly and completing the compaction operation until the required maximum compaction is obtained. 9.7 Maximum compaction and optimum moisture content (AASHTO T-180) must be quality-checked during construction at the rate one sample per 500 feet internal along the full length of the project using nuclear moisture-density methods and the proctor values also verified. 10. Finishing The surface of the 8 to 10 inch layer of chemically treated recycled base material shall be shaped and compacted to the required lines, grade, and cross-section specified in the Contract Documents. 11. Grade of Finished Surface Control The surface of the recycled base shall be brought to line grade and shaped to the specified cross-section. Grades shall be set longitudinally and transversely with fixed 6 Copyrighted 2004 Dallas Roadway Products, Inc.

7 controls not to exceed 25 feet spacing c-c. The compacted base material shall be placed in 1 to 2 lifts (depending on the roller weight), compacted and smoothed over its full width using a pneumatic-tire and smooth-faced wheeled roller. The finished grade shall not deviate more than 0.5 inches from the established grade after the addition of an 8 to 10 inch thick, treated, compacted, crushed rock base over the subgrade/subbase. 12. Compaction Immediately after placement or completion of the in-place mixing of aggregate and chemical stabilizer, the treated aggregate material shall be compacted with a heavy (10 to 20 ton) rubber-tired roller to a density not less than 98% of maximum dry density as determined by AASHTO T-180 at +/-1% of the aggregate s optimum water content. The contractor will provide a randomly selected AASHTO T-180 specimen one every 500 feet Compaction operations, except on super-elevated curves, shall begin at the sides of course, overlap the shoulder or berm at least one (1) ft and progress toward the center parallel to the centerline of the roadway. Super-elevated curve compaction shall begin at the low side of the super-elevation and progress toward the high side. The compaction shall continue until all compaction marks are eliminated. 13. Construction Joints At the end of each day s construction, a straight transverse joint shall be formed by cutting back into the completed work to form a vertical face. The base for large, wide areas shall be built in a series of parallel lanes of convenient length and width, complete with longitudinal joints, as approved by the Engineer. 14. Protection and Curing All spreading, compacting, and shaping shall be completed immediately after mixing the chemical soil/ stabilizer-stabilizer and soil / road base have come into contact. Any section not conforming to these requirements shall be reconstructed as directed by the Engineer The compacted, treated base shall be allowed to cure for a period of up to 2 days measured from the date of treatment and compaction or as determined by the Engineer. During this period the completed project shall be closed to all traffic. Until acceptance by the owner s representative, any damages caused by construction equipment, shall be repaired at the Contractor s expense. 15. Maintenance During construction and after completion of the treated recycled base, it shall be maintained by the Contractor until road is placed in operation. Unacceptable work that 7 Copyrighted 2004 Dallas Roadway Products, Inc.

8 cannot be repaired shall be replaced to the full depth of recycled base course at the Contractor s expense. 16. Measurement and Payment General. The payment will be full compensation for demolishing, furnishing, hauling, pulverizing and mixing, placing, compacting, watering, control strip and for all labor equipment, tools, and incidentals necessary to complete work. Payment shall be made at the unit price bid per square yard for Item SPL-1 Scarifying, Grading, Rolling, and Compaction Imported base course will be measured and paid for at the Contract unit price per cubic yard (cy) for Item 304 Recycled base. Payment for excavation shall be made at the unit bid for Item 203 Excavation Including Embankment Construction Chemical soil/stabilizer-stabilizer will be measured and paid for at the Contract unit price per US Gallon rounded to the next highest gallon. This is concentrated gallons, not diluted gallons, Item SPL-2. 8 Copyrighted 2004 Dallas Roadway Products, Inc.