6 SEC 400.pdf

DEPARTMENT OF TRANSPORTATION

STATE OF GEORGIA

SPECIAL PROVISION

This work includes constructing a cement stabilized base course by pulverizing the existing flexible pavement, underlying base and subgrade, and mixing with Portland cement. Construct according to these specifications and to the lines, grades, thickness, and typical cross-sections shown on the plans or established by the Engineer.

General Provisions 101 through 150

Section 109—Measurement and Payment

Section 300—General Specifications for Base and Subbase Courses

Section 301—Soil-Cement Construction

Section 412—Bituminous Prime

Section 415—Asphaltic Concrete Open Graded Crack Relief Interlayer

Section 424—Bituminous Surface Treatment

Section 814—Soil Base Materials

Section 821—Cutback Asphalt

Section 822—Emulsified Asphalt

Section 824—Cationic Asphalt Emulsion

Section 830—Portland Cement

Section 880—Water

GDT 19 – Determining Maximum Density of Soil-Cement mixtures

GDT 20 – Determining Field Density of soils with <45% retained on the No. 10 sieve and < 10% retained on the 1 in. sieve

GDT 21 - Determining Field Density of soils containing >45% retained on the No.10 sieve or >10% retained on the 1 in. sieve

GDT 59 - Testing Density of roadway materials with Nuclear Gauge

GDT 65 – Laboratory Design of Soil-Cement and Cement Stabilized Graded Aggregate

GDT 67 – Family of Curves Method for determining Maximum Density of soils http://tomcat2.dot.state.ga.us/thesource/pdf/specs/ss105.html http://tomcat2.dot.state.ga.us/thesource/pdf/specs/ss105.html http://tomcat2.dot.state.ga.us/thesource/pdf/specs/ss105.html http://tomcat2.dot.state.ga.us/thesource/pdf/specs/ss412.html http://tomcat2.dot.state.ga.us/thesource/pdf/specs/ss815.html http://tomcat2.dot.state.ga.us/thesource/pdf/specs/ss821.html http://tomcat2.dot.state.ga.us/thesource/pdf/specs/ss823.html http://tomcat2.dot.state.ga.us/thesource/pdf/specs/ss823.html

Section 315 — Cement Stabilized Reclaimed Base Construction (CSRB)

GDT 86 – Determining the compressive strength of Cement Stabilized Base cores taken from the roadway

Prior to construction, submit a Construction Work Plan to the Engineer consisting of the proposed equipment, materials, and operation procedures. If the Engineer determines that the work plan is not satisfactory, revise the procedures and augment or replace equipment, as necessary, to complete the work.

The Contractor shall submit a mix design to the Office of Materials and Testing for approval at least three weeks prior to construction. The Mix Design process shall be completed in accordance with GDOT Test Method/GDT 65 by an accredited materials laboratory. The sampling, testing, proportioning, and documentation shall be completed by an accredited materials laboratory. The Contractor will be responsible for ensuring that appropriate traffic control measures are in place during the sampling operations. In-place samples of the road structure shall be taken at a minimum frequency of 1000 ft. (300m) per two lanes; alternating the sample locations to achieve a sample every 500 lane-feet (152m). Additional samples may be needed to represent material changes and/or problem areas. Each sample shall contain at least 30 lbs. (14kg) of proportionally blended materials to be reclaimed. The Portland cement used in the design process must be from an approved source listed on GDOT’s Qualified Products List/QPL3 and representative of the same material to be used in construction.

The mix design submittal to the Office of Materials and Testing shall include the following:

1. Approximately 100 lbs. (45kg) of proportionally blended material from all in-place samples taken from the roadway.

2. A one-gallon sample (plastic container) of the stabilizer used in the mix design.

3. All test data (charts, graphs, spreadsheets, etc.) along with design parameters. Test data should include the target gradation of the blended material, optimum moisture content of mixing, and application rate of the stabilizer to meet the design requirements.

Note: Since the Mix Design is based on source specific materials, any changes to materials or sources will render the design invalid.

Ensure that materials meet the requirements of the following GDOT Standard Specifications:

Material Section

Blotter material (sand) 412.3.05.G.3

Soil-Cement Material 814.2.02

Cutback asphalt, RC-30, RC-70, RC-250 or MC-30, MC-70, MC-250 821.2.01

Portland Cement (Type I, Type II, or Type IL) 830.2.01

Water 880.2.01

Emulsified Asphalt *AEP, EAP-1 822.2.01

Cationic Emulsified Asphalt CSS-1h, CRS-2 824.2.01 http://tomcat2.dot.state.ga.us/thesource/pdf/specs/ss412.html#ss412.3.05.g.3 http://tomcat2.dot.state.ga.us/thesource/pdf/specs/ss815.html http://tomcat2.dot.state.ga.us/thesource/pdf/specs/ss821.html#ss821.2.01 http://tomcat2.dot.state.ga.us/thesource/pdf/specs/ss823.html#ss823.2.01 http://tomcat2.dot.state.ga.us/thesource/pdf/specs/ss412.html#ss412.3.05.g.3

Ensure that only experienced and capable personnel operate equipment.

Equipment used in CSRB construction must meet the following requirements and be approved by the Engineer prior to the beginning of construction. All equipment shall be in satisfactory condition and capable of its intended purpose. The Engineer may at any time reject any equipment that is deemed unsafe, erratic, or produces an inadequate performance.

Note: Equipment type, size, operation, and condition are subject to the Engineer’s approval and must be adjusted and/or replaced upon their request.

CSRB will require a reclaimer unit that meets the following requirements:

1. Designed expressly for reclamation capable of pulverizing and mixing through asphaltic pavement, granular/soil base, subbases, and subgrade down to depths of at least 12 in. (300mm).

2. Have a cutting drum with a minimum width of 8 ft. (2m).

3. Capable of continuously mixing materials to a homogenous blend and at a consistent depth.

4. Powered by an engine of at least 500 horsepower with steerable front and rear wheels.

5. Controlled by an electronic metering system capable of injecting water directly into the mixing chamber and has automatic sensors to monitor water application and mixing depth.

For CSRB construction, use a cyclone-type mechanical spreader, or its equivalent, that will spread Portland cement in a relatively dust-free process. The spreader must have an electronic or mechanical metering system which monitors the application rate.

Note: The use of pneumatic tubes to transfer cement or lime directly onto the roadway will not be allowed.

Additional equipment necessary to complete the work must be in satisfactory condition and proper for its intended purpose. Compactive equipment includes a sheepfoot/padfoot roller, vibratory steel wheel roller and a pneumatic rubber tire roller. Use the correct size/type rollers or combination thereof that is capable of achieving the required density. A pressure distributor that complies with GDOT Standard Specifications/Subsection 424.3.02.B will be required to apply the bituminous prime coat.

Note: Equipment type, size, operation, and condition are subject to the Engineer’s approval and must be adjusted and/or replaced upon their request.

Prior to commencing reclaiming operations, blade grass and excess soil a minimum of 12 in. (300mm) from the edge of pavement. Locate, mark, and preserve existing centerline, manholes, and utilities (gas, water, and electric lines).

Relocate mailboxes and other appurtenances within such proximity to the roadway as to risk damage or interfere with the work. Remove sections of driveway aprons in the Right-of-Way where necessary to permit the reclaimer to operate without damaging the machinery or driveway pavement. If necessary, saw-cut a neat parallel line to the proposed edge of pavement and remove the concrete along the road. After all work is complete, replace appurtenances to their original location as nearly as possible.

1. Mix only when the weather permits the course to be finished without interruption and within the time specified.

2. Mix materials only when the moisture of the materials to be used in the mixture meets the specified limits.

3. Begin mixing only when the air temperature is above 40°F in the shade and rising.

Adjust the moisture content of the roadway materials to within 100 to 120 percent of the optimum moisture immediately before spreading the cement. The optimum moisture content is determined by the Job Mix Design and can be adjusted by the Engineer.

1. Apply cement on days when wind will not interfere with spreading.

2. Apply cement at the rate specified on the Job Mix Design (as established by GDT-65) and mix to the depth shown on the Plans. The Engineer may alter the spread rate during the progress of construction if necessary.

Maintain the application rate within + 10 percent of that specified by the Engineer.

3. Provide both equipment and personnel to measure the application rate of cement placed. Each tanker of cement shall be checked by using a square yard cloth/certified scales and by determining the overall coverage area of each tanker. Multiple checks may be necessary to ensure that the spread rate is maintained within the ± 10 percent limit.

4. If the cement content falls below the 10 percent limit in the mixing area, add additional cement to bring the affected area within the tolerance specified, make necessary adjustments to the spreader, and perform additional checks to ensure the problem is corrected. If the cement content is more than the 10 percent limit in the mixing area, the excess quantity will be deducted from the Contractor’s pay for cement.

5. Regulate operations to limit the application of cement to sections small enough so that all of the mixing, compacting, and finishing operations can be completed within the required time limits.

6. Pass only spreading and mixing equipment over the spread cement and operate this equipment so that it does not displace cement.

7. Replace damaged cement at no cost to the Department when damage is caused by:

a. Hydration due to rain, before or during mixing operations.

b. Spreading procedures that are contrary to the requirements stated above.

c. Displacement by the Contractor’s equipment or other traffic.

1. Begin mixing as soon as possible after the cement is spread and continue until a homogeneous and uniform mixture is produced. The Engineer at any time may require adjustments or replacement of equipment if a homogeneous and uniform mixture conforming to these Specifications is not achieved.

2. Continue pulverizing until the base mixture is uniform in color and conforms to the following gradation requirements:

a. 100 percent passing the 3 in. sieve (76.2mm) or the natural size of the in-situ aggregate.

b. 55 percent of the roadway material, excluding gravel, passing the No. 4 sieve (4.75mm).

3. Add water as needed to maintain or bring the moisture content to within the moisture requirements immediately after the preliminary mixing of the cement and roadway material.

4. Mix the additional water homogeneously into the full depth of the mixture.

1. Test Section

a. A test section shall be constructed with the first tanker of cement delivered to the project. The length of the test section will be determined by the area in which the entire tanker of cement will cover.

b. The Engineer will evaluate compaction, moisture, homogeneity of mixture, thickness of stabilization, and finished base surface. If the Engineer deems necessary, revise the compaction procedure or replace equipment.

2. Time Limits

a. Begin compaction within 45 minutes of the time of the mixing of cement.

b. Complete compaction within 2 hours after the cement has been applied.

c. Do not perform vibratory compaction on materials more than 90 minutes old, measured from the time cement was added to the mixture.

d. Complete all operations within 4 hours from adding cement to finishing the surface.

3. Moisture Control

a. During compaction, ensure that the moisture is uniformly distributed throughout the mixture at a level of between 100 and 120 percent of the optimum moisture content.

4. Compaction Requirements

a. Use a sheep’s foot roller/padfoot roller, steel wheel roller or pneumatic-tired roller for initial compactive effort unless an alternate method is approved by the Engineer.

b. Compact the cement-stabilized base course to at least 98 percent of the maximum dry density established on the Job Mix Design.

c. Uniformly compact the mixture and then shape to the grade, line, and cross-section shown on the Plans.

d. Remove all loosened material accumulated during the shaping process. Do not use additional layers of cement-treated materials in order to conform to cross-sectional or grade requirements.

e. Use a pneumatic-tired roller to roll the finished surface until it is smooth, closely knit, and free from cracks or deformations, and conforming to the proper line, grade, and cross-section.

f. In places inaccessible to the roller, obtain the required compaction with mechanical tampers approved by the Engineer. Apply the same compaction requirements as stated in this subsection.

g. Perform grading operations immediately after the placement and compaction operations. Roll the stabilized base course again with a pneumatic-tired roller.

1. Form a straight transverse joint at the end of each day’s construction or whenever the work is interrupted.

2. Create the straight transverse joint by cutting back into the completed work to form a true vertical face free of loose or shattered material.

3. Form the joint at least 2 ft. (0.6m) from the point where the spreader strike-off plate comes to rest at the end of the day’s work, or at the point of interruption.

Material Layer Thickness

Cement Stabilized Reclaimed Base (CSRB) One layer not to exceed 10 in. (254 mm)

4. Form a longitudinal joint, as described above, if cement-stabilized mixture is placed over a large area where it is impractical to complete the full width during one day’s work. Use the procedure for forming a straight transverse joint. Remove all waste material from the compacted base.

1. The surface of the completed base course must be moist cured until the bituminous prime is applied.

2. Apply prime only to an entirely moist surface. If weather delays prime application, apply prime as soon as the surface moisture is adequate.

3. Apply bituminous prime according to GDOT Standard Specifications/Section 412 as soon as possible and in no case later than 24 hours after completion of the finishing operations.

4. Protect finished portions of the cement-stabilized base course that are used by equipment in the construction of an adjoining section to prevent marring or damaging of the completed work. Protect the stabilized area from freezing during the curing period.

5. Apply cure coat depending on project ADT:

• < 400 ADT: Prime and sand.

• ≥ 400 ADT: Apply single 89 surface treatment layer according to Section 424 or asphaltic concrete open graded crack relief interlayer according to Section 415.

1. Correct any failures caused by traffic at no additional cost to the Department. Make repairs specified in

GDOT Standard Specifications/Subsection 300.3.06.B whenever defects appear. This preservation action does not relieve the Contractor of his responsibility to maintain the work until final acceptance, as specified in

GDOT Standard Specifications/Section 105.

1. Determine the maximum dry density from representative samples of compacted material, according to GDOT

Test Method/GDT 19 or GDT 67.

2. Determine the in-place density of finished courses according to GDOT Test Method/GDT 20, GDT 21 or

GDT 59 as soon as possible after compaction but before the cement sets.

1. Ensure that the gradation of the completely mixed cement-stabilized base course meets the requirements as stated above in Subsection 315.3.04.D.2.

1. Check the finished surface of the cement-stabilized base course transversely using one of the following tools:

a. A template cut true to the required cross-section and set with a spirit level on non-super elevated sections.

b. A system of ordinates measured from a string line.

c. A surveyor’s level.

2. Ensure the ordinates measured from the bottom of the template, string line, or straightedge, to the surface do not exceed ½ in. (12.7mm) at any point.

http://tomcat2.dot.state.ga.us/thesource/pdf/auxdata/gdt/gdt021.html http://tomcat2.dot.state.ga.us/thesource/pdf/auxdata/gdt/gdt059.html

1. Determine the thickness of the cement-stabilized base course by making as many checks as necessary to determine the average thickness, but not less than one check per 1000 ft. (304.8m) per 2 lanes. Checks shall be taken after the completion of the base course and prior to priming.

2. If any measurement is deficient in thickness by more than ½ in. (12.7mm), make additional measurements to isolate the affected area. Correct any area deficient by more than ½ in. (12. 7mm) to the design thickness by using one of the following methods:

a. Apply GDOT approved asphaltic concrete 9.5mm Superpave.

A. Reconstruct to the required thickness.

No payment will be made for any Asphaltic Concrete 9.5mm Superpave used to correct deficiencies, nor will payment be made for removing and reconstructing the deficient work.

3. If any measurement exceeds thickness by more than ½ in. (12.7mm), make additional measurements to isolate the affected area. If the basis of payment is per cubic yard and the average thickness for any mile increment exceeds the allowable ½ in. (12.7mm) tolerance, the excess quantity in that increment will be deducted from the Contractor’s payments. The excess quantity is calculated by multiplying the average thickness that exceeds the allowable ½ in. (12.7mm) tolerance by the surface area of the base, as applicable.

Measure the surface length along the centerline when payment is specified by the square yard. The width is specified on the plans. Measure irregular areas, such as turnouts and intersections, by the square yard.

Measure Portland cement by the ton.

Bituminous prime is not measured for separate payment. Include the cost of furnishing and applying bituminous prime according to the provisions of GDOT Standard Specifications/Section 412 in the Unit Price Bid for each individual base item.

Cement-stabilized base, in-place and accepted, will be paid for at the Contract Unit Price per square yard.

Payment will be full compensation for roadbed preparation, mixing on the road, shaping, pulverizing, watering, compaction, defect repair, bituminous prime and maintenance.

Portland cement will be paid for at the Contract Unit Price per ton. Payment is full compensation for furnishing, hauling, and applying the material. Only Type I, Type II, or Type IL Portland cement incorporated into the finished course will be paid for, and no payment will be made for cement used to correct defects due to the Contractor’s negligence, faulty equipment, or error.

Payment will be made under:

Item No. 315 Cement Stabilized Reclaimed Base Course Per square yard (meter)

Item No. 315 Portland Cement Per ton (megagram)

Asphaltic Concrete Open Graded Crack Relief Interlayer mix is paid for at the Contract Unit Price per ton (megagram). Payment is full compensation for furnishing and placing materials including asphalt cement, hydrated lime, approved additives, and for cleaning and repairing, preparing surfaces, hauling, mixing, spreading, rolling, and performing other operations to complete the Contract Item.

The accepted area of surface treatment will be paid for at the Contract Unit Price per square yard (meter) complete for Item No. 424 Single surface treatment stone size __ group__ Per square yard (meter).