### **ITEM P-211 LIME ROCK BASE COURSE**

DESCRIPTION

**211-1.1**  This item shall consist of a base course composed of lime
rock constructed on the prepared underlying course in accordance with
these specifications and shall conform to the dimensions and typical
cross section shown on the plans.

MATERIALS

**211-2.1 MATERIALS**.  The lime rock base course material shall consist
of fossiliferous limestone of uniform quality, and shall not contain
hard or flinty pieces that will cause a rough surface containing pits
and pockets.  The rock shall show no tendency to \`\`air slake\'\' or
undergo chemical change when exposed to the weather. The material when
watered and rolled shall be capable of being compacted into a dense and
well-bonded base.

The oolitic type of lime rock shall meet the following requirements:

Carbonates of calcium and magnesium - not less than 70%. 

Oxides of iron and aluminum - not more than 2%. 

The combined amount of carbonates, oxides, and silica shall be at least
97%.  The material shall be non-plastic.

All other types of lime rock shall contain not less than 95% of
carbonates of calcium and magnesium.  Liquid limit shall not exceed 35,
plasticity index shall not exceed 6, as determined in accordance with
ASTM D 4318.

The chemical analysis of lime rock shall consist of determining the
insoluble silica, iron oxide, and alumina by solution of the sample in
hydrochloric (HCl) acid, evaporating, dehydrating, redissolving the
residue, and neutralizing with ammonium hydroxide, filtering, washing,
and igniting the residue lime rock.  The difference between the
percentage of insoluble matter and 100% is reported as carbonates of
calcium and magnesium.

The lime rock shall not contain more than 0.5% of roots, leaf mold,
organic, or foreign matter and shall be obtained from pits from which
all overburden has been removed previous to blasting and quarrying.

The gradation of the lime rock shall meet the following requirements:  

Sieve Designation Percentage by Weight

(square openings) Passing Sieves

3‑1/2 inch (90.mm) 100

3/4 inch (19.0 mm) 50-100

All fine material shall consist entirely of dust of fracture.

CONSTRUCTION METHODS

**211-3.1 SOURCES OF SUPPLY**.  All work involved in cleaning and
stripping pits, including the handling of unsuitable material shall be
performed by the Contractor at his/her own expense.  The lime rock shall
be obtained from approved sources.  The pits shall be operated in such a
manner that a clean and uniform material will be secured.

**211-3.2 EQUIPMENT**.  All equipment necessary for the proper
construction of this work shall be on the project, in first-class
working condition, and approved by the Engineer before construction is
permitted to start.

**211-3.3 PREPARING UNDERLYING COURSE**.  The underlying course shall be
checked and accepted by the Engineer before placing and spreading
operations are started.  Any ruts or soft yielding places caused by
improper drainage conditions, hauling, or any other cause shall be
corrected at the Contractor\'s expense before the base course is placed
thereon. Material shall not be placed on frozen subgrade.

**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 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
shall have the required thickness.  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 which shall apply to only the top layer.

The rock shall be transported to locations 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, forks, or approved
mechanical spreaders especially constructed for this purpose.  In no
case shall rock be dumped directly onto 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
brought to the proper moisture content to obtain maximum density.  If
water is added, it shall be uniformly mixed to the full depth of the
course by discing.  All segregated areas of fine or coarse rock shall be
removed and replaced with well-graded rock, and approved by the
Engineer.  Lime rock shall not be spread when the subgrade is in an
unsuitable condition.

The lime rock base course shall be constructed in a layer not less than
4 inches (100 mm) nor more than 6 inches (150 mm) of compacted
thickness.  The base course shall be constructed in lanes or strips
parallel with the centerline of the paved area.

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 after completion of the spreading
operations, the base material shall be thoroughly compacted.  The
number, type, and weight of rollers shall be sufficient to compact the
mixture to the required density.

The field density of the compacted material shall be at least 100
percent of the maximum density of laboratory specimens prepared from
samples of the base material delivered to the jobsite.  The laboratory
specimens shall be compacted and tested in accordance with **\[ \]**. 
The in-place field density shall be determined in accordance with ASTM D
1556.  The moisture content of the material at the start of compaction
shall not be below nor more than 1-1/2 percentage points above the
optimum moisture content.

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> **The Engineer shall specify ASTM D 698 for areas designated for
> aircraft with gross weights of 60,000 pounds (27 200 kg) or less and
> ASTM D 1557 for areas designated for aircraft with gross weights
> greater than 60,000 pounds (27 200 kg).**

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**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 3 inches (75 mm) and shaped to the exact crown and cross section
with a blade grader.  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 4 days. 
When the lime rock base is constructed in two layers, the scarifying of
the surface shall be to a depth of 2 inches (50 mm).

If, in the opinion of the Engineer, the surface of the base is glazed or
cemented to the extent that the prime coat could not penetrate properly,
and after determining that the condition of the base meets all
requirements, he will direct that the surface of the base be hard-planed
with a blade grader and broomed immediately prior to the application of
the prime coat.  This hard-planing shall be done in such a manner that
only the glazed or cemented surface is removed, leaving a granular or
porous condition that will allow free penetration of the prime material.
The material planed from the base shall be removed from the base area.

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, and 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 failures by rescarifying,
reshaping, watering, rolling, and adding lime rock where necessary.

**211-3.7 SURFACE TOLERANCE**.  After the course has been completely
compacted, the surface shall be tested for smoothness and accuracy of
grade and crown.  Any portion lacking the required smoothness or failing
in accuracy of grade or crown shall be scarified, reshaped, recompacted,
and otherwise manipulated as the Engineer may direct until the required
smoothness and accuracy are obtained.  The finished surface shall not
vary more than 3/8 inch (9 mm) from a 16-foot (4.8 mm) straightedge when
applied to the surface parallel with, and at right angles to, the
centerline.  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 a
manner that each test shall represent 300 square yards (250 square
meters), or it shall be as otherwise directed by the Engineer.  The
depth tests shall be made by test holes through the base at least 3
inches (75 mm) in diameter.  Where the base deficiency is more than 1/2
inch (12 mm), the Contractor shall correct such areas by scarifying and
adding rock.  The base shall be scarified, rock added, and tapered a
distance of 100 feet (30 m) 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, 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 1/2-inch (12 mm)
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 1/4 inch (6 mm) of the thickness
shown on the typical cross section.  On individual depth measurements,
thicknesses more than 1/2 inch (12 mm) in excess of that shown on the
plans shall be considered as specified thickness plus 1/2 inch (12 mm)
in computing the average job thickness.  The Contractor shall replace,
at his/her expense, the lime rock removed from test holes.

**211-3.9 PROTECTION**.  Work on the base course shall not be
accomplished 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.

Hauling equipment may be routed over completed portions of the base
course, provided no 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/her opinion, such hauling is causing
damage.  Any damage resulting to the base course from routing equipment
over the base course shall be repaired by the Contractor at his/her own
expense.

**211-3.10 MAINTENANCE**.  Following the completion of the base course,
the Contractor shall perform all maintenance work necessary to keep the
base course in a condition satisfactory for priming.  After priming, the
surface shall be kept clean and free from foreign material.  The base
course shall be properly drained at all times.  If cleaning is
necessary, or if the prime coat becomes disturbed, any work or
restitution necessary shall be performed at the expense of the
Contractor.

METHOD OF MEASUREMENT

**211-4.1**  The quantity of lime rock base course to be paid for shall
be the number of cubic yards (cubic meters) 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 1 depth test for
each 300 square yards (250 square meters) of base course, or by means of
average end areas on the complete work computed from elevations to the
nearest 0.01 foot (3 mm).  On individual depth measurements, thicknesses
more than 1/2 inch (12 mm) in excess of that shown on the plans shall be
considered as the specified thickness plus 1/2 inch (12 mm) in computing
the yardage for payment.

BASIS OF PAYMENT

**211-5.1**  Payment shall be made at the contract unit price per cubic
yard (cubic meter) for lime rock base course.  This price shall be full
compensation for furnishing all materials and for all preparation,
hauling, and placing of these materials, and for all labor, equipment,
tools, and incidentals necessary to complete the item.

The cost of removing cracks and checks including the labor and material
for repriming, and the additional lime rock necessary for crack
elimination, will not be paid for separately but shall be included in
the contract price per cubic yard (cubic meter) for lime rock base
course.

Payment will be made under:

Item P-211-5.1 Lime rock base course per cubic yard (cubic meter) 

TESTING REQUIREMENTS

ASTM C 136 Sieve Analysis of Fine and Coarse Aggregates

ASTM D 698 Moisture-Density Relations of Soils and Soil Aggregate
Mixtures Using 5.5-lb (2.49-kg) Rammer and 12-in (305 mm) Drop

ASTM D 1556 Density of Soil in Place by the Sand-Cone Method

ASTM D 1557 Test for Laboratory Compaction Characteristics of Soil Using
Modified Effort

ASTM D 4318 Liquid Limit, Plastic Limit, and Plasticity Index of Soils

END OF ITEM P-211