Page 4-4 M 41-10
4-04 Ballast and Crushed Surfacing4-04 Ballast and Crushed Surfacing
4-04.1 Description
This Work consists of constructing one or more courses of crushed stone upon a prepared Subgrade in accordance with these Specifications in conformity with the lines, grades, depth, and typical cross-sections shown in the Plans or as established by the Engineer. This Work consists of furnishing and placing crushed surfacing base course or planing material along the edge of the paved shoulders after paving the top lift of HMA. Surfacing materials and ballast may also be specified to be placed in stockpiles for future use.
4-04.2 Materials
Materials shall meet the requirements of the following sections: Ballast 9-03.9(1) Permeable Ballast 9-03.9(2) Crushed Surfacing 9-03.9(3) Shoulder Finishing 9-03.9(3) Maintenance Rock 9-03.9(4) Asphalt planings used in lieu of Crushed Surfacing for shoulder finishing shall have a nominal maximum aggregate size of 1 1/2”.
4-04.3 Construction Requirements
4-04.3(1) Equipment
All equipment necessary for the satisfactory performance of this construction shall be on the project and approved by the Engineer prior to beginning work. If central mix plant methods are used, the central mixing plant shall comply with the following requirements: The cold aggregate feeder shall be mechanically operated and adjustable to the extent necessary to provide a uniform and continuous flow of materials. These materials shall be deposited in an approved mixer with a sufficient amount of water being added to obtain the required density when spread and compacted. The water shall be weighed or metered and dispensed through a device providing uniform dispersion across the mixer. The mixing plant shall be provided with weighing or calibrating devices, feeders, provisions for sampling, and other devices and equipment so designed, coordinated, and operated to produce a uniform mixture, and to permit the sampling of the materials before and after mixing. The mixer shall be kept in good condition, and mixing blades or paddles shall be of proper size, adjustment, and clearance to provide positive and uniform mixing of the mixture at all times. The capacity of the plant and equipment furnished for the Work shall be adequate at all times to provide for efficient and continuous operations insofar as practical.
4-04.3(2) Subgrade
The Subgrade shall be prepared as specified in Section 2-06 and shall be approved by the Engineer before placing ballast or surfacing materials. M 41-10 Page 4-5 Ballast and Crushed Surfacing 4-044-04.3(3) Mixing Unless otherwise specified, the Contractor may use either, or both, of the following described methods:
1.Central Plant Mix Method – The surfacing material and water shall be mixed in an approved mixing plant as described in Section 4-04.3(1) . The completed mixture shall be a thoroughly mixed combination of proportioned materials and water, uniform in distribution of particle sizes and moisture content. A mixture containing water in excess of the proportion established by the Engineer will not be accepted.
2.Road Mix Method – After material for each layer of surfacing has been placed, the material shall be mixed until uniform throughout by motor graders or other equipment approved by the Engineer. Water to facilitate mixing and compacting shall be added in amounts approved by the Engineer.
4-04.3(4) Placing and Spreading
1.Central Plant Mix Method – After mixing, material for each layer of surfacing shall be transported to the Roadway in approved vehicles. Vehicles for hauling the mixture shall be capable of depositing the mixture within the receiving hopper of the spreading equipment, or in windrows of uniform size in front of the spreading equipment, with a minimum of segregation of the mix. A motor grader may be used as the spreading machine or the spreading machine shall be capable of receiving the material by direct deposit in its hopper from the hauling vehicle or from a uniform windrow and be capable of spreading and screeding the material to a depth and surface that when compacted will be true to line, grade, depth of course, and cross-section without further shaping.
2.Road Mix Method – Each layer of surfacing material shall be spread by equipment that is approved by the Engineer. Equipment that causes segregation of the surfacing material during the spreading operation will not be allowed. Similar types of spreading equipment shall be used throughout the limits of each separate spreading operation. Spreading on small areas of less than 2,000 square yards or on areas irregular in shape, may be accomplished by other means as approved by the Engineer. The following nominal depth of compacted material shall not be exceeded in any one course without the approval of the Engineer: Ballast 0.50 foot Gravel Base 0.75 foot Crushed Surfacing 0.35 foot
4-04.3(5) Shaping and Compaction
Immediately following spreading and final shaping, each layer of surfacing shall be compacted to at least 95 percent of maximum density determined by the requirements of Section 2-03.3(14)D before the next succeeding layer of surfacing or pavement is placed. The determination of field in-place density shall be made by a nuclear density gauge. When the thickness of surfacing is less than 0.15 foot, density testing will not be required and the Engineer will determine the number of coverages required for the particular compaction equipment available. Vibratory compactors and rollers shall obtain the specified density for each layer. A mist spray of water shall be applied as needed to replace moisture lost by evaporation. The completed layer shall have a smooth, tight, uniform surface true to the line, grade, and cross-section shown in the Plans, or as staked. When using 100% Recycled Concrete Aggregate, the Contractor may submit a written request to use a test point evaluation for compaction acceptance testing in lieu of compacting to 95% of the standard density as determined by the requirements of Section
2-03.3(14)D The test point evaluation shall be performed in accordance with SOP 738.
Page 4-6 M 41-10
4-04 Ballast and Crushed Surfacing4-04.3(6) Keystone
When necessary, as determined by the Engineer, crushed surfacing top course shall be used for keystone to key the top surface of ballast, gravel base, crushed surfacing base course, or any other surfacing course that requires keying. The keystone shall be spread evenly on top of the surfacing course by means of approved spreading equipment. The surface shall be watered and, if necessary, bladed lightly until the keystone is worked into the interstices of the surfacing course without excessive displacement and shall be compacted. The operations of adding keystone, wetting, blading, and compacting shall be continued until the course has become thoroughly keyed and compacted. When keystone is required, that is subject to public traffic, it shall be placed before terminating each day’s operation. Keystone placed for the convenience of the Contractor, with approval of the Engineer, for the purpose of creating a denser surface on which to pave will be allowed within the top 0.20 foot of crushed surfacing base course, gravel base, or ballast. Keystone placed for this purpose will be paid for at the lower unit Contract price for either the base material being keyed or crushed surfacing top course.
4-04.3(7) Miscellaneous Requirements
The surface of each layer of surfacing material shall be maintained true to line, grade, and cross-section by grading, watering, and rolling until placing the next succeeding course. The first course of surfacing material shall be placed on all available Subgrade before placing the succeeding course unless otherwise authorized by the Engineer. The Contractor shall maintain a minimum distance of not less than one full station between the construction of any two courses of surfacing or ballast, unless otherwise approved. Should irregularities develop in surfaces during or after compaction, they shall be remedied by loosening the surface and correcting the defects after which the entire area including the surrounding surface shall be thoroughly recompacted. All additional materials necessary to make the repairs shall be furnished by the Contractor at the unit Contract price.
4-04.3(8) Weather Limitations
When, in the opinion of the Engineer, the weather is such that satisfactory results cannot be obtained, the Contractor shall suspend operations until the weather is favorable. No surfacing materials shall be placed in snow or on a soft, muddy, or frozen Subgrade.
4-04.3(9) Hauling
Hauling equipment shall be routed over the Roadway in a manner to be most effective in the compacting of the surfacing. Hauling over the surfacing in the process of construction will not be permitted when, in the opinion of the Engineer, the effect will be detrimental. All loads shall be of uniform capacity unless deviation is expressly authorized by the Engineer.
4-04.3(10) Hours of Work
The Contractor shall arrange surfacing operations so that the placing of materials will be accomplished during daylight hours. However, when necessary to complete the project within the time specified, or to avoid peak periods of public traffic, Work may be undertaken during the hours of darkness, provided the Contractor furnishes and operates adequate lighting. Inability to demonstrate reliable and satisfactory results will be reason to order termination of night operations, and the Contractor shall procure additional equipment and personnel necessary to satisfactorily complete the Work as specified while operating during daylight hours only. M 41-10 Page 4-7 Ballast and Crushed Surfacing 4-044-04.3(11) Shoulder Finishing After paving the top lift of HMA, shoulder finishing material shall be placed against the vertical edge of the pavement, including road approaches, as detailed in the Plans. Hand work may be required in areas of guardrail. Processing of the shoulder finishing material on the adjacent pavement surface will not be permitted. Shoulder finishing materials shall be graded into place and compacted by wheel rolling a minimum of two passes with a motor grader or comparable piece of equipment to produce a firm and unyielding surface. The density requirements of Section 4-04.3(5) shall not apply to shoulder finishing material. Placement and compaction of shoulder finishing material will be visually accepted by the Engineer. Following the placement of shoulder finishing material each day, the adjacent pavement shall be cleaned of all dirt and debris in accordance with Section 8-01.3(8) .
4-04.3(12) Permeable Ballast
Permeable ballast shall not be placed until the abutting surface has been completed unless designated by the Engineer. Processing of the permeable ballast course on the Roadway will not be permitted. Compaction shall be accomplished by making a minimum of three passes over the aggregate with a vibratory compactor of a type acceptable to the Engineer. The density requirements of Section 4-04.3(5) shall not apply). Placement and compaction of the material will be visually accepted by the Engineer.
4-04.4 Measurement
Crushed surfacing top course, base course, ballast, and gravel base, when mixed at a central plant, will be measured by the ton. The weight of water added at the plant will be deducted on a daily basis from the total tonnage of aggregates, including water, placed that day which were processed through the central plant and placed on the Roadway. The resultant tonnage of surfacing materials will be paid for at the unit Contract price. The weight of deducted water will be converted to gallons and will be paid for at the unit Contract price for water. Crushed surfacing top course, base course, ballast, and gravel base, when mixed by the road mix method, will be measured by the ton or by the cubic yard. If measured by the cubic yard, measurement will be made in the hauling conveyance at the point of delivery on the Roadway. Permeable ballast will be measured by the ton or by the cubic yard. Crushed surfacing materials for placement in stockpile will be measured by the ton or cubic yard. If measured by the cubic yard, the volume will be determined by cross- sectioning the stockpile. Maintenance rock will be measured in the same manner prescribed for crushed surfacing materials. Water used in placing and compacting surfacing materials on the Roadway will be measured in accordance with Section 2-07 . Shoulder finishing along each shoulder finished will be measured to the nearest 0.01 mile, along the Roadway centerline. Deductions will be made for driveways and intersecting roadways. Areas not finished such as curbed areas, bridges, and guardrail sections will not be measured. Page 4-8 M 41-10
4-04 Ballast and Crushed Surfacing4-04.5 Payment
Payment will be made for each of the following Bid items that are included in the Proposal: “Crushed Surfacing Top Course (or Base Course)”, per ton, or per cubic yard. “Crushed Surfacing Top Course (or Base Course) in Stockpile”, per ton, or per cubic yard. “Crushed Surfacing Top Course (or Base Course) from Stockpile”, per ton, or per cubic yard. “Ballast”, per ton, or per cubic yard. “Ballast in Stockpile”, per ton, or per cubic yard. “Ballast from Stockpile”, per ton, or per cubic yard. “Permeable Ballast”, per ton, or per cubic yard. “Permeable Ballast in Stockpile”, per ton or per cubic yard. “Permeable Ballast from Stockpile”, per ton or per cubic yard. “Maintenance Rock ½ In. Minus in Stockpile”, per ton, or per cubic yard. “Shoulder Finishing”, per mile. The unit Contract price per mile for “Shoulder Finishing” shall be full payment for all costs incurred to furnish crushed surfacing material, hauling, placing, watering, compaction, and cleaning of adjacent pavement.
Source: Washington Standard Specifications for Road, Bridge, and Municipal Construction, 2024 Edition. Pages 274–278 of 1,151.