(b) Travel plant method.—After the material for each course has been placed through an aggregate spreader or window sizing device the material shall be uniformly mixed by a traveling mixing plant. During the mixing, water shall be added in an amount sufficient to provide the necessary moisture content for compacting. (c) Road mix method.—After material for each course has been placed, the materials shall be mixed while at required moisture content by means of motor graders or other approved equipment until the mixture is uniform throughout. 304.07 Placing. The material shall be placed on the prepared roadbed and compacted in layers of the thickness shown on the plans. When more than one layer is required, each layer shall be shaped and compacted before the succeeding layer is placed. If the Contractor elects to produce and stockpile aggregates prior to placement on the roadbed, the aggregates shall be stockpiled in accordance with the requirements of Section 311. The placing of material shall begin at the point designated by the Engineer. Placing shall be from vehicles especially equipped to distribute the material in a continuous uniform layer or windrow. The layer or windrow shall be of such size that when spread and compacted the finished layer shall be in reasonably close conformity to the nominal thickness shown on the plans. When hauling is done over previously placed material, hauling equipment shall be dispersed uniformly over the entire surface of the previously constructed layer, to minimize rutting or uneven compaction. 304.08 Spreading and Compacting. When uniformly mixed, the mixture shall be spread smoothly for compaction to the plan thickness. Immediately following final spreading and smoothing, each layer shall be compacted to the full width by means of approved compaction equipment meeting requirements set forth in Section 212. Rolling shall progress gradually from the sides to the center, parallel to the centerline of the road, and shall continue until all the surface has been rolled. Any irregularities or depressions that develop shall be corrected by loosening the material at these places and adding or removing material until the surface is smooth and uniform. Along curbs, headers, and walls, and at all places not accessible to the roller, the base material shall be compacted thoroughly with approved tampers or compactors. The surface will be tested for acceptance by the Engineer with a 10-foot straight edge after the base has been bladed and rolled into a smooth surface. Any areas where the surface variation exceeds 1⁄2 inch in 10 feet shall be reworked until the variation falls within this limit. Compaction of each layer shall continue until a density of not less than 95 percent of the maximum density determined in accordance with AASHTO T 180 Method D, or other approved method, has been achieved. Compaction procedures outlined in Section 212 may be utilized. In-place field density determinations will be made in accordance with AASHTO T 191, T 205, or other approved method. The use of AASHTO T 224 to correct for oversize particles may be required. The Engineer will make measurements of test holes at random during progress of the work to determine the depth of uncompacted layers required to produce the designated depth of material after compacting to the specified density. Cutting of the test holes and refilling with materials properly compacted shall be done by the Contractor under the supervision of the Engineer. 304.09 Thickness. (a) When payment is by the ton, the Engineer will make measurements of test holes at random during progress of the work to determine the thickness of uncompacted layers required to produce the designated thickness of material after compacting to the specified density. Cutting of the test holes and refilling with materials properly compacted shall be done by the Contractor under the supervision of the Engineer. (b) When payment is by the square yard, at least 50 percent of all covered areas shall equal or exceed the thickness shown on the plans and no areas shall be deficient by more than 1⁄2 inch. The Engineer will verify compliance with these requirements by checking the depth of randomly selected test holes located at intervals of 300 to 2,000 linear feet. Additional test holes may be required to identify the limits of deficient areas. The Contractor shall correct deficient areas by adding material and finishing to an acceptable grade. The digging, refilling, and compacting of these holes shall be done by the Contractor at locations designated by the Engineer. Method of Measurement 304.10 The quantity to be paid for will be the number of tons, or square yards of material, including all filler, placed, compacted, and accepted in the completed course. Scale weights of material shall be adjusted to deduct the daily average moisture content in excess of 2 percent over optimum moisture. The measurement of quantities will not include any chemical additives paid for as a separate pay item. When slag and stone (or gravel) are designated as alternative materials for pay items in the bid schedule and payment is by weight, the estimated quantities will be based on assumed average bulk specific gravities of available alternative materials. No adjustment in contract unit price will be made for variation in quantity due to differences in the specific gravity of the material actually used. Chemical additives will be measured by the ton. If sacked additives are used, the net weight as packed by the manufacturer will be used for measurement. When payment is by the square yard, the width for measurement will be the width shown on the plans for the item plus any additional width ordered by the Engineer. The length will be the distance measured horizontally along the centerline of each roadway, approach road, or ramp. Basis of Payment 304.11 The quantities, determined as provided above, will be paid for at the contract price per unit of measurement for each pay item listed below that is shown in the bid schedule, which price and payment will be full compensation for the work of this section with the following exceptions: (a) Clearing and grubbing of pits and quarries will not be paid for directly, but will be considered as a subsidiary obligation of the Contractor. (b) Roadbed preparation will be included under the work of Section 208. (c) When any pay factor for a lot of aggregate base course or subbase is less than 1.00, as determined in subsection 304.04, payment for the material in that lot will be made at a reduced price arrived at by multiplying the contract unit price for the item by that pay factor. If payment is by the square yard and the material is placed in multiple lifts, payment for the material in that lot will be arrived at by multiplying the contract unit price per square yard by the ratio of the lift thickness to the total plan thickness and then multiplying by the applicable pay factor. If more than one pay factor is less than 1.00, the lowest pay factor shall apply. 305.01 This work shall consist of the reconditioning and preparing of previously constructed subgrades, aggregate bases and surfaces and flexible pavements to improve its load bearing capacity by stabilization or by adding additional courses of materials. The work shall be done in reasonably close conformity with the lines, grades and cross sections shown on the plans or staked by the Engineer. Materials 305.02 Aggregate. Aggregate for stabilization shall conform to subsection 703.18 for the grading shown in bid schedule. Aggregate samples for acceptance testing will be taken at the point of production. 305.03 Chemical Additives. Chemical additives shall meet the requirements of the following subsection: 305.04 Subgrade and ditches. The entire subgrade including ditches and slopes, if required, shall be bladed, leveled, loosened, reshaped and otherwise brought to grade. The subgrade shall be dried or watered as necessary to secure compaction in accordance with Section 203. All slide material including inlet and outlet debris, shall be removed and disposed of as required. Culverts shall be cleaned out. 305.05 Aggregate subbase, base and surfacing. The upper layer of existing subbases, bases and surfacings shall be scarified, bladed, pulverized, leveled and reshaped as shown on the plans or as directed by the Engineer. The quantity of aggregate for stabilization, as designated on the plans, shall be placed, windrowed, and brought to a uniform section. The windrowed materials shall be blended together until all materials are uniformly distributed throughout the combined windrow. If required, chemical additives shall be uniformly distributed and thoroughly mixed with the windrow. Borrow if required shall meet the requirements of Section 203 and be paid thereunder. The compacted grade shall be cured with a bituminous material when a soil-cement mixture is specified. 305.06 Asphalt payments. Existing bituminous surface shall be scarified and pulverized until all lumps are reduced to a size not greater than 11⁄2 times that of the maximum size aggregate and shall then be windowed or otherwise conserved for further use in the work, if not incorporated and compacted in the roadbed. 305.07 Removal and replacement of unsuitable material. Any soft, unstable or other unsuitable materials in the roadbed shall be removed as directed and replaced with suitable material or stabilized by means of chemical additives included in the schedule, as directed by the Engineer. The material shall be placed in loose layers of not more than 8 inches in depth and each layer shall be thoroughly compacted. 305.08 Compaction. Compaction shall be in accordance with Section 304.08. 305.09 Protection of Roadbed. At all times, ditches and drains along the roadbed shall be cleaned and maintained so as to drain effectively. In no case shall any base course, surface course, or pavement be placed on a frozen, muddy, or unstable roadbed. 305.10 Finishing and Curing. If a base or surface course is included in the contract, the surface of the completed subgrade shall be satisfactorily maintained until the base or surface course has been placed. If required, additional water shall be applied to prevent checking or raveling. Method of Measurement 305.11 Reconditioning will be measured by the mile and shall include all blading of ditches and shoulders if required, the scarifying and pulverizing of the existing roadbed, the preparation, incorporation, or conservation of existing bituminous materials, the compacting of the roadbed, the finishing of the surface, and the maintenance of the completed surface. Aggregate for subgrade modification will be measured by the cubic yard, truck measure or ton in accordance with Section 109–Measurement and Payment. Moisture in the aggregate will be deducted in accordance with subsection 304.10. When slag and stone (or gravel) are designated as alternative materials for pay items in the bid schedule and payment is by weight, the estimated quantities will be based on assumed average bulk specific gravities of available materials. No adjustment in contract unit price will be made for variation in quantity due to differences in the specific gravity of the material actually used. Water will be measured by the M.G. (1,000 gallons) by means of calibrated tanks or distributors or by means of accurate water meters furnished by the Contractor. Only that water which is used in mixing materials or ordered by the Engineer to keep the surface moist will be measured for payment. Removal and replacement of unsuitable material in the roadbed will be measured for payment under Section 203. Patching and leveling material will be measured for payment under the applicable sections. Chemical additives ordered by the Engineer and acceptably incorporated into the roadbed will be measured by the ton. Basis of Payment 305.12 The accepted quantities of reconditioning determined as provided above will be paid for the contract unit price per mile, per ton or cubic yard for aggregates, per M.G. (1,000 gallon) for water and per ton for chemical additives. Asphalt and cement will not be paid for separately. Water will be paid for under Section 207. Payment will be made under: Pay item 305(1) Reconditioning of roadbed 305(2) Aggregate, grading.... 305(3) Aggregate, grading. 305(4) Chemical additive. Pay unit Cubic yard Ton Section 306.-RESERVED Section 307.-RESERVED Section 308.-PORTLAND CEMENT TREATED BASE COURSE 308.01 Description This work shall consist of constructing one or more courses of a mixture of aggregate and portland cement on a prepared surface in accordance with these specifications in reasonably close conformity with the lines, grades, thicknesses and typical cross sections shown on the plans or established by the Engineer. Unless otherwise provided, the Contractor may use either the travel plant or central plant method as described below. 308.02 Materials Materials shall conform to the requirements specified in the following subsections: Fly ash may be substituted for a portion of the Portland cement at the option of the Government. The percent of fly ash will be determined by laboratory tests. Construction Requirements 308.03 Travel Plant Method. The aggregate obtained from scarifying the existing roadway or from other sources shall be pulverized until at least 80 percent of all material other than stone or gravel will pass a No. 4 sieve and 100% will pass a 1-inch sieve, prior to compaction. Any material retained on a 2-inch sieve and other unsuitable material shall be removed. If additional material is specified, it shall be blended with the existing material. All butt joints at existing pavement or other structures shall be cleaned prior to mixing. The subgrade shall support all equipment required in the construction of the base. Soft or yielding areas shall be corrected prior to mixing. The aggregate to be treated shall be placed in a uniform windrow or spread to a uniform thickness to the width required. The specified quantity of portland cement shall be applied uniformly in a trench on top of the windrow or spread uniformly over the aggregate. Spread cement that has been lost shall be replaced, without additional compensation, before mixing is started. Mixing shall be accomplished by means of a mixer that will thoroughly blend the aggregate with the cement. The mixer shall be equipped with a water metering device that will introduce the required quantity of water during the mixing cycle. The cement-aggregate mixture shall be sufficiently blended to prevent the formation of cement balls when water is applied. A maximum time of 2 hours shall be permitted for wet mixing, lay-down, and finishing when the "Travel Plant Method" is used. Other mixing methods and equipment may be used for areas consisting of 10,000 square yards or less when approved. |