607.05 Method of Measurement.
sand or hot -mix. To avoid movement or damage to the geotextile membrane, turning of the paver and other vehicles shall be gra dual and kept to a minimum.
f.Seal Coats . Prior to placing a seal coat (or thin overlay such as an open -graded friction course), the geotextile shall be lightly sanded at a spread rate of 1.5 to 2.0 pounds per square yard {0.8 to 1.1 kg/m²} and pneumatic ally rolled so as to embed the geotextile tightly into the sealant.
607.05 Method of Measurement.
The paving geotextile will be measured by the square yard {square meter}. Asphalt sealant for the paving geotextile will be measured by the gallon {liter}.
607.06 Basis of Payment.
a.General . The accepted quantities of paving geotextiles will be paid for at the contract unit price per square yard {square meter} in place. Accepted quantities of asphalt sealant for the paving geotextile will be paid for at the contract unit price per gallon {liter} complete in place.
b.Payment will be made under Item No .: 607-D Paving Geotextile - per square yard {square meter} 607-E Asphalt Sealant - per gallon {liter} GEOTEXTILES IN SEPARATION APPLICATIONS
608.01 Description.
This section shall cover the furnishing and placing of geotextiles for use as a permeable separator to prevent mixing of dissimilar materials such as subgrades and surfaced and un surfaced pavement structures, zones in embankments, foundations, and select fill materials. The geotextiles shall be designed to allow passage of water while retaining in situ soil without clogging. When used as a soil stabilizer, a detailed design process shall be followed taking into consideration the separation function of the geotextile, along with its filtration and reinforcement functions.
608.02 Materials.
The geotextile shall meet the requirements of AASHTO M 288 for Separation Applications, Class 2 , and Section 810 of these Specifications. The geotextile shall be selected from List II -3, of the Department's manual titled "Materials, Sources, and Devices With Special Acceptance Requirements". Information concerning this list is given in Subarticle 10 6.01(f) and ALDOT -355.
608.03 Construction Requirements.
The installation site shall be prepared by clearing and grading the area as required. All sharp objects and large stones shall be removed and trees and shrubs shall be cut flush with the subgrade. The removal of top soil and vegetation is not necessary. When appropriate, soft spots and unsuitable areas shall be identified during site preparation or subsequent proof rolling. These areas shall be excavated and backfilled with select material which is compacted to a depth such that the area provides equal stability as the adjacent area. Stabilization of these areas may be enhanced by use of a geotextile at the bottom of the excavation before backfill.
608.04 Installation.
The geotextile shall be unrolled as smoothly as possible on the prepared subgrade in the direction of the construction traffic. Adjacent geotextile rolls shall be overlapped in the direction of subbase placement using the following guide:
609.01 Description.
Required Overlaps Soil Strength (CBR) Unsewn Overlap (inches {mm}) Sewn Overlap (inches {mm}) < 1 - - 9 {225} 1 - 2 38 {950} 8 {200} 2 - 3 30 {750} 3 {75} > 3 24 {600} - - Unless shown otherwise on the plans, the required overlap shall be as shown for a CBR value of 1 - 2. The geotextile may be held in place prior to subbase placement by pins, staples, or piles of fill or rock. Geotextiles may be folded or cut to conform to any curvature of the area. A fold or overlap shall be in the direction of construction and held in place a s prescribed above.
608.05 Seams.
Both factory and field sewn or sealed seams shall conform to the strength requirements of Table 1 as outlined in AASHTO M 288 for Separation Applications. All seams shall be subject to the approval of the Engineer.
608.06 Subbase Placement.
The subbase shall be placed by end dumping onto the geotextile from the edge of the geotextile, or over previously placed subbase aggregate. On subgrades having a CBR of 1, the subbase aggregate shall be spread simultaneously with dumping to minimize the potential of a localized subgrade failure. Direct traffic on the geotextile, along with any sudden stops, starts, or turns on the subbase material by construction equipment, shall be avoided where possible. Using whatever means, the subbase material shall be spread from the back dumped pile. Except in the case of low volume roads (ADT < 200), a minimum thickness of 6 inches {150 mm} shall be maintained. In the case of low volume roads, this thickness shall be 4 inches {100 mm}. A smooth drum roller shall be used to achieve the specified density. Any ruts occurring during construction shall be filled with additional subbase material and compacted to the specified density. The use of vibratory compaction will not be allowed a s it may cause damage to the geotextile.
608.07 Damage Repair.
Damaged geotextiles, as identified by the Engineer, shall be repaired immediately. The damaged area, plus an additional 3 feet {1 m} around the area, shall be cleared of all fill material. This area shall be covered with a geotextile patch extending 3 feet {1 m} beyond the perimeter of the damage. The removed subbase material shall be replaced and compacted to the specified density.
608.08 Method of Measurement.
The geotextile will be measured by the square yard {square meter} from the payment lines shown on the plans, or from the payment lines established in writing by the Engineer. This excludes seam overlaps. Excavation, backfill, bedding, and cover material are separate pay items.
608.09 Basi s of Payment.
a.General . The accepted quantities of geotextiles will be paid for at the contract unit price per square yard {square meter} in place.
b.Payment will be made under Item No .: 608-A Separation Geotextile - per square yard {square meter} SECTION 609 AGGREGATE SLOPE PROTECTION
609.01 Description.
This Section shall cover the work of furnishing and constructing a slope protection layer of graded aggregat e on slopes as shown on the plans or directed in accordance with these Specifications. This
Source: Alabama Standard Specifications for Highway Construction, 2022 Edition. Pages 485–485 of 934.