211-3.4 PLACING AND SPREADING. All base course material shall be placed on the prepared underlying course and compacted in layers to the thickness shown on the plans. The depositing and spreading of the material on the prepared course or on a completed layer shall commence where designated and shall progress continuously without breaks. The material shall be deposited and spread in lanes in a uniform layer and without segregation of size to such loose depth that, when compacted, the layer will have the required thickness. It shall be the charge of the contractor that the required amount of approved material is delivered in each 100-foot station. When more than one layer is required the construction procedure described herein shall apply similarly to each layer, excepting the scarifying and rerolling of the surface. This shall apply to only the top layer.

The rock shall be transported to the points where it is to be used over rock previously placed, and dumped at the end of the preceding spread. It shall then be spread uniformly with shovels or forks or with spreaders especially constructed for this purpose. In no case shall rock be dumped directly on the underlying course. Transporting over the underlying course will not be permitted except as directed, in which case it must be protected by planking if rutting occurs. During the dumping and spreading operations the rock shall be thoroughly saturated with water as required. All segregated areas of fine or coarse rock shall be removed and replaced with well-graded rock to the satisfaction of the engineer. Lime rock shall not be spread when the subgrade is in unsuitable condition.

The lime rock base course shall be constructed in a layer of not less than four (4) inches nor more than six (6) inches of compacted thickThe base course shall be constructed in lanes or strips parallel with the centerline of the paved area.

ness.

During the placing operation, sufficient caution shall be exercised to prevent the incorporation of subgrade, subbase, or shoulder material in the lime rock.

211-3.5 ROLLING. Immediately following final spreading, the material shall be compacted to full width by rolling with a power roller or other approved compacting equipment. Rolling shall progress gradually from the sides to the center of the lane under construction, or from one side toward previously placed material, and shall continue until all the surface has been rolled and compacted. Rolling shall continue until the base material has been compacted to not less than ninety-five (95) percent density as determined by the CAA compaction control tests T-611 for the class of airport involved. Large irregularities or depressions that develop under rolling shall be corrected by loosening the material at these places and adding or removing materials until the surface is smooth and uniform. Prior to and during compaction, water in the amounts as directed shall be applied as specified above. Sufficient rollers shall be furnished to properly compact the base course based on seventy (70) square yards per roller per hour of continuous operation. Blading and rolling shall be done alternately as required or directed to obtain a smooth, even, surface and until the

entire depth of base is compacted into a dense, unyielding mass. Rerolling of previous day's spread shall be done as directed. When the shoulder back-fill material has been placed, the shoulder shall be thoroughly rolled and compacted.

Along curbs, headers, and all places inaccessible to the roller, the base course material shall be tamped thoroughly with mechanical or hand tampers. Each hand tamper shall weigh not less than fifty (50) pounds and have a face area of not more than one hundred (100) square inches.

211-3.6

FINISHING BASE COURSE. After the watering and rolling of the base course, the entire surface shall be scarified to a depth of at least three (3) inches and shaped to the exact crown and cross section with a road machine. The scarified material shall be rewatered and thoroughly rolled. Rolling shall continue until the base is bonded and compacted into a dense, unyielding mass, true to grade and cross section. The scarifying and rolling of the surface of the base shall follow the initial rolling of the lime rock by not more than four (4) days. When the lime rock base is constructed in two layers, the scarifying of the surface shall be to a depth of two (2) inches.

If at any time the underlying material becomes churned up and mixed with the base course material, the contractor shall, without additional compensation, dig out and remove the mixture, reshape and compact the underlying course, replace the materials removed with clean rock which shall be watered and rolled until satisfactorily compacted.

Where cracks, checks, or failures appear in the base either before or after priming and before the surface course is laid, the contractor shall remove such cracks, checks, or failure by rescarifying, reshaping, watering, rolling, and adding lime rock where necessary.

211-3.7 SURFACE TEST. The finished surface of the base course shall be tested with a sixteen (16) foot straightedge laid parallel to and at right angles to the centerline of the runway, and all irregularities greater than three-eighths (%) inch corrected by scarifying to a depth of not less than three (3) inches, removing or adding rock as may be required, after which the entire area shall be watered, rolled, and brought to a satisfactory state of compaction. In testing surface of the harder lime rocks, measurement of clearances from the straightedge shall not include small holes caused by individual pieces being pulled out by the grader.

211-3.8 THICKNESS. The thickness of the base course shall be determined by depth tests or elevations taken at intervals in such manner that one measurement shall represent 300 square yards, or as directed by the engineer.

The depth tests shall be made by test holes through the base at least three (3) inches in diameter. Where the base deficiency is more than one half (2) inch, the contractor shall correct such areas by scarifying and adding rock. The base shall be scarified, rock added, and tapered out for a distance of one hundred (100) feet in each direction from the edge of the deficient area for each inch of rock

added. The affected area shall then be watered, bladed, rolled, and brought to a satisfactory state of compaction and of required thickness and cross section. The thickness of the base in the affected area shall be remeasured by depth tests or elevations. The operations of scarifying, adding rock, and rerolling shall continue until the base thickness is within the one-half inch tolerance of base thickness. The final base thickness of the reconditioned area shall be used to determine the average job thickness.

The average job thickness shall be the average of the depth measurement as above outlined, and shall be within one-quarter (4) inch of the thickness as shown on the typical cross section. On individual depth measurements, thicknesses more than one-half (2) inch in excess of that shown on the plans shall be considered as specified thickness plus one-half (1⁄2) inch in computing the average job thickness. The contractor shall replace, at his expense, the lime rock removed from test holes. 211-3.9

PROTECTION. Work on the base course shall not be prosecuted during freezing temperatures nor when the subgrade is wet. When the aggregate contains frozen materials, or the underlying course is frozen, the construction shall be stopped.

In general, hauling equipment may be routed over completed portions of the base course, provided no excessive damage results and provided that such equipment is routed over the full width of the base course to avoid rutting or uneven compaction. However, the engineer in charge shall have full and specific authority to stop all hauling over completed or partially completed base course when, in his opinion, such hauling is causing excessive damage. Any damage resulting to the base course from routing equipment over the base course shall be repaired by the contractor at his own expense.

211-3.10 MAINTENANCE. Following the final shaping of the material, the base shall be maintained throughout its entire length by the use of a standard road machine or motor grader and rollers until such time as, in the judgment of the engineer, the base meets the required density, is properly bonded, and is suitable for priming. After the mixing and shaping is completed, the base shall be confined to the specified width by banking enough shoulder material against the edges to prevent it from spreading under traffic. The base shall be properly drained at all times. During this maintenance period, any deficiencies in thickness, smoothness, or density shall be corrected in a satisfactory manner.

Before prime coat is applied, the base course shall be allowed to partially dry until the average moisture content of the full depth of base is less than eighty (80) percent of the optimum moisture of the base mixture. The drying shall not continue to the extent that the surface of the base becomes dusty with consequent loss of thickness of the base. If during the curing period the surface of base dries too fast, it shall be kept moist by sprinkling until such time as the prime coat shall be applied as directed.

METHOD OF MEASUREMENT

211-4.1 The yardage of lime rock base course to be paid for shall be the number of cubic yards of base material placed, bonded, and accepted in the completed base course. The quantity of base course material shall be measured in final position based upon depth tests taken as directed by the engineer at the rate of one depth test for each 300 square yards of base course, or by means of average end areas on the complete work computed from elevations to the nearest 0.01 foot. On individual depth measurements, thicknesses more than one-half inch in excess of that shown on the plans shall be considered as the specified thickness plus one-half inch in computing the yardage for payment.

BASIS OF PAYMENT

211-5.1 The yardage of lime rock base course measured as provided above shall be paid for at the contract unit price bid per cubic yard for lime rock base course, which price and payment shall constitute full compensation for furnishing, loading, hauling, and placing the material; for blading, sprinkling, shaping, and compacting; for reconditioning the underlying course and shoulders; for reconstruction of irregular surface, or deficient thickness; for curing and for maintenance; for scarifying and rerolling; for refilling test holes; for any required construction, repair, and obliteration of access roads; for all pit moves; for clearing, stripping, drainage, and clean-up of pits; for the handling and disposal of unsuitable materials encountered in pit operations; and for all labor, equipment, tools, water, and incidentals necessary to complete the work.

The cost of removing cracks and checks as provided above including the labor and material for repriming, and the additional lime rock where necessary on account of such crack elimination, will not be paid for separately but shall be included in the contract price per cubic yard for lime rock base course.

Payment will be made under:

Item P-211-5.1 Lime Rock Base Course-per cubic yard.

ITEM P-212 SHELL BASE COURSE

DESCRIPTION

212-1.1 This item shall consist of a base course composed of shell and binder constructed on a prepared underlying course in accordance with these specifications and in conformity with the dimensions and typical cross section shown on the plans and with the lines and grades established by the engineer.

212-2.1

MATERIALS.

MATERIALS

The shell shall consist of durable particles of "dead" oyster or clam shell. The base material shall consist of oyster shell together with an approved binding or filler material so blended or processed as to produce a uniform mixture complying with the requirements of these specifications as to gradation, soil constants, and capability of being compacted into a dense and well-bonded base. Clam shell may be used in combination with oyster shell in the proportion up to and including fifty (50) percent.

The shell shall be reasonably clean and free from excess amount of clay or organic matter such as leaves, grass, roots, and other objectionable and foreign material.

The gradation of the blended or processed material shall meet the requirements of the gradation given in the table below, using A. A. S. H. O., Methods T-11 and T-27.

That portion of the material, including the blended filler, passing a No. 40 mesh sieve shall be known as soil binder and shall have a liquid limit of not more than 25 and a plasticity index of not more than 8 as determined by A. A. S. H. O. Methods T-89 and T-91, respectively. If necessary, the contractor will be required to blend or combine materials so that the finally processed material meets all of the requirements of these specifications. The contractor will be required to