- 158 - SECTION 303 -- SUBGRADE STABILIZATION
303.01 Description
1.The Contractor shall complete the following requirements under the "Subgrade Stabilization" bid item:
a.Provide and place soil binder (cohesive soil). b. Mix soil binder into non-cohesive sand in the upper subgrade. c. Adjust grade lines to meet intersections, pavements, bridge ends, railroad crossings, or any other physical features.
d.Dispose of surplus excavated or profiled material. e. Scarify, adjust the moisture , shape, and compact soils as is necessary to conform to the contract.
303.02 Material Requirements
1.Soil binder shall conform to the requirements of Section 1034.
2.Soil binder shall be obtained according to the requirements of Subsection 205.02.
303.03 Construction Methods
1.The Contractor shall number, l abel, tally, and prepare a report of quantities and distribution of the materi als delivered. A copy of the report shall be given to the Engineer at the end of each day when hauling materials.
2.When the grading is complete, the Engineer will determine the quantity of soil binder the Contractor shall provide to stabilize subgrade sand.
3.Soil binder shall be pulverized to the extent that at least 90% will pass a 1/2 inch (12.5 mm) sieve and at least 60% will pass a No. 10 (2 mm) sieve. The binder shall be pulverized be fore it is mixed with the subgrade sand.
4.After the Contractor has thoroug hly mixed the soil binder with the subgrade sand, the upper 6 inches (150 mm) of the subgrade shall be compacted to the optimal stiffness as defined by a deflection target value established by the Engineer. Moisture may be added as necessary to obtain proper compaction. The moisture target value for granular materials shall be established in the field by the Contractor during the compaction process and may be adjusted at the discretion of the Engineer. Once established the target moisture shall not vary by more than +2%.
5.After the Contractor attains t he required stiffness, the stabilized subgrade shall be profiled in accordan ce with the requirements of Subsection 302.03.
6.In all cut areas and those fill areas graded under a separate contract, correcting faulty subgrade conditions below the 6 inch (150 mm) depth will be performed as "extra work " unless such conditions are caused by the Contractor's operations.
303.04 Method of Measurement
1.Water will be measured as described in Subsection 302.04. Subgrade Stabilization 303.05 - 159 - 2. Soil Binder will be measured for payment by the cubic yard (cubic meter) when it is delivered. The Contractor shall level the material even with the top of the truck's cargo box to allow accurate volume measurement.
3.Subgrade Stabilization will be me asured in stations of 100 feet (100 m). Stations shall be measured hor izontally along the project centerline between the beginning and ending points. Deductions will be made for all areas not stabilized with soil binder. The work of stabilizing subgrade outside the width shown in the typical cross section in the contract, including intersections and driveways, will be measured for payment in equivalent stations. The number of stations for which payment will be made will be the quotient that is obtained by dividing the surface area of the wo rk outside the typical section by the surface area of one station of the adjacent roadway.
303.05 Basis of Payment
1.Pay Item Pay Unit Soil Binder Cubic Yard (CY) [ C u b i c M e t e r ( m3)] Subgrade Stabilization Station (Sta) [Station (StaM)] Water 1,000 Gallons (MGAL) [ K i l o l i t e r ( k L ) ]
2.Payment is full compensation for a ll work described in this Section. - 160 - SECTION 304 -- EARTH SHOULDER CONSTRUCTION
304.01 Description
The Contractor shall complete the following requirements under the "Earth Shoulder Construction" bid item:
1.Furnish and excavate the embankment material. 2. Haul, compact, blade, and shape the material to conform to the contract’s typical cross sections and compaction requirements.
3.Construct embankments as necessary to adjust the grade line of intersecting roads and driveways to meet the elevation of the new shoulder surfaces.
304.02 Material Requirements
1.The Contractor shall be required to obtain and furnish material unless otherwise shown in the contract.
2.Soils shall meet the require ments described in Section 205.
304.03 Construction Methods
1.The Contractor shall construct earth shoulders in accordance with the requirements of Sections 201 and 205.
2.When the final elevation of the traveled way is different from the elevation of intersecting roads and driv eways, the Contractor shall adjust the grade line of intersecting roads and dr iveways to meet the elevation of the new surfaces. The existing grade line will be adjusted 5 feet horizontally for each inch (2 m horizontally for each 35 mm) of vertical change in the surfacing elevation.
3.During shoulder constr uction, the embankments shall be adequately drained to prevent dam age to the pavement structure.
4.Shoulder materials shall not be placed along the traveled way more than 15 days ahead of their intended use. The shoulder material may be placed near the edge of pavement over night provided it is graded and compacted in a manner so that a vehicle can drive safely over it.
5.The Contractor shall construc t shoulders to the typical cross sections shown in the contract.
a.The shoulder shall be tight bladed using a motorgrader to remove any vegetation. The underlying subgrade shall be scarified to a depth of 6 inches (150 mm) and then compacted with at least two complete coverages over the area with an approved roller.
b.Shoulder construction shall match the existing width and fill slope or plan section widths, whichever is widest.
6.Earth Shoulders (Asphaltic Concrete Surfacing) a. When a beveled edge is required and installed in accordance with contract, the earth shouldering shall begin and be completed within the following time limits:
1.The latest the Contractor shall begin "Earth Shoulder Construction" is the eighth calendar da y of placement of the top layer of asphalt pavement.
Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 192–193 of 1,048.