### **ITEM P-306 ECONOCRETE BASE COURSE**

#### 

#### DESCRIPTION

**306-1.1** This item shall consist of a subbase material, herein termed
econocrete, that is composed of aggregate and cement uniformly blended
together and mixed with water. The mixture may also include approved
cementitious additives, in the form of fly ash or slag, and chemical
admixtures. The mixed material shall be spread, shaped, and consolidated
using concrete paving equipment in accordance with these specifications
and in conformity to the lines, grades, dimensions, and typical
cross-sections shown on the plans.

#### MATERIALS

**306-2.1 AGGREGATE**. The coarse aggregate fraction shall be crushed
stone, crushed or uncrushed gravel, crushed and adequately seasoned,
air-cooled, iron blast furnace slag, crushed recycled concrete, or a
combination thereof. The fine aggregate fraction may be part of the
natural aggregate blend as obtained from the borrow source or it may be
natural sand that is added at the time of mixing.

The aggregate shall consist of hard, durable particles, free from an
excess of flat, elongated, soft, or disintegrated pieces, or
objectionable matter (e.g., roots, sod, weeds, organic impurities,
etc.). A flat particle is one having a ratio of width to thickness
greater than five; an elongated particle is one having a ratio of length
to width greater than five.

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>
> The Engineer should specify limits for deleterious materials using
> guidance contained in ASTM C 33.
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The design aggregate blend shall conform to one of the gradations shown
in Table 1, when tested in accordance with ASTM C 136.

Table 1. Aggregate gradation for econocrete.

+--------------------+------------------------+------------------------+
| **Sieve Size**     | **Percentage by Weight |                        |
|                    | Passing Sieves**       |                        |
| **(square          |                        |                        |
| openings)**        |                        |                        |
+--------------------+------------------------+------------------------+
|                    | **1½ -in (37.5-mm)     | **1-in (25-mm)         |
|                    | Maximum**              | Maximum**              |
+--------------------+------------------------+------------------------+
| 2 in (51 mm)       | \--                    | \--                    |
|                    |                        |                        |
| 1½ in (37.5 mm)    | 100                    | \--                    |
|                    |                        |                        |
| 1 in (25 mm)       | 70 - 95                | 100                    |
|                    |                        |                        |
| ¾ in (19 mm)       | 55 - 85                | 70 - 100               |
|                    |                        |                        |
| No. 4 (4.75 mm)    | 30 - 60                | 35 - 65                |
|                    |                        |                        |
| No. 40 (425 µm)    | 10 - 30                | 15 - 30                |
|                    |                        |                        |
| No. 200 (75 µm)    | 0 - 15                 | 0 -- 15                |
+--------------------+------------------------+------------------------+

**306-2.2 CEMENT**. Cement shall conform to the requirements of ASTM \[
\].

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> The Engineer shall specify ASTM C 150 Type I, II, III, IV, or V or
> ASTM C 595 Type IS, IS-A, IP, IP-A, P, or PA. Type II cement shall be
> specified in areas with a history of sulfate reaction with the
> selected aggregate.
>
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**306-2.3 CEMENTITIOUS ADDITIVES**. Pozzolanic and ground granulated
blast furnace (GGBF) slag may be added to the econocrete mix. If used,
each material must meet the following requirements:

a.  Pozzolan. Pozzolanic materials must meet the requirements of ASTM C
    618, Class F Flyash.

b.  Ground Granulated Blast Furnace Slag (Slag Cement). Slag shall
    conform to ASTM C 989, Grade 80, 100 or 120.

**306-2.4 CHEMICAL ADMIXTURES.** The Contractor shall submit
certificates indicating that the material to be furnished meets all the
requirements listed below. In addition, the Engineer may require the
Contractor to submit complete test data showing that the material to be
furnished meets all the requirements of the cited specification.

a.  Air-Entraining Admixtures. Air-entraining admixtures shall meet the
    requirements of ASTM C 260.

b.  Water-Reducing Admixtures. Water-reducing, set-controlling
    admixtures shall meet the requirements of ASTM C 494, Type A,
    water-reducing or Type D, water-reducing and retarding.
    Water-reducing admixtures shall be added at the mixer separately
    from air-entraining admixtures in accordance with the
    manufacturer\'s printed instructions. The air entrainment agent and
    the water-reducing admixture shall be compatible.

**306-2.5 WATER**. Water used in mixing or curing shall be clean and
free of oil, salt, acid, alkali, sugar, vegetable, or other deleterious
substances injurious to the finished product. Water will be tested in
accordance with the requirements of AASHTO T 26. Water known to be of
potable quality may be used without testing.

**306-2.6 CURING MATERIALS**. For curing econocrete, use
white-pigmented, liquid membrane-forming compound conforming to ASTM C
309, Type 2, Class A or Class B (wax-based) or Asphalt emulsion
conforming to the requirements of ASTM D 977, Type SS-1h..

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**The Engineer may add additional curing materials Modify the Bond
Breaker paragraph accordingly.**

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#### COMPOSITION OF MIXTURE

**306-3.1 MIX DESIGN**. The econocrete mix design shall be based on
trial batch results conducted in the laboratory. The econocrete shall be
designed to meet the criteria in this section.

**306-3.1.1 Compressive Strength***.* Compressive strength shall not be
less than 500 psi (3,445 kPa) nor greater than 800 psi (5,516 kPa) at 7
days. 3-day and 7-day strengths shall be taken as the average of two
compressive strength test results. All compressive strength specimens
shall be prepared and tested in accordance with ASTM C 192 and ASTM C
39, respectively.

If the 3-day strength is greater than 500 psi (3,447 kPa), the
Contractor shall construct transverse joints in the econocrete layer in
accordance with paragraph 306-5.10.2.

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> In locations subject to freeze-thaw cycles, insert the following "The
> freeze-thaw weight loss shall not exceed 14 percent when tested in
> accordance with ASTM D 560."
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If there is a change in aggregate sources, type of cement used, or
pozzolanic materials, a new mix design must be submitted.

**306-3.1.2 Air Content.** The percentage of air entrainment shall be 6
percent, plus or minus 1/2 percent. Air content shall be determined by
testing in accordance with ASTM C 231 for gravel and stone coarse
aggregate and ASTM C 173 for slag and other highly porous coarse
aggregate.

**306-3.2 SUBMITTALS**. At least \[ \] days prior to the placement of
the econocrete, the Contractor shall submit certified test reports to
the Engineer for those materials proposed for use during construction,
as well as the mix design information for the econocrete material. Tests
older than 6 months shall not be used. The certification shall show the
appropriate ASTM or AASHTO specifications or tests for the material, the
name of the company performing the tests, the date of the tests, the
test results, and a statement that the material did or did not comply
with the applicable specifications. The submittal package shall include
the following:

a.  Sources of materials, including aggregate, cement, admixtures, and
    curing and bond breaking materials.

b.  Physical properties of the aggregates, cement, admixtures, curing
    and bond breaking materials.

c.  Mix design.

-   mix identification number.

-   weight of saturated surface-dry aggregates (fine and coarse).

-   combined aggregate gradation.

-   cement factor.

-   water content.

-   water-cementitious material ratio (by weight).

-   volume of admixtures and yield for one cubic yard (cubic meter) of
    econocrete.

d.  Laboratory test results.

-   slump.

-   air content.

-   compressive strength at 3, 7, and 28 days (average values).

-   wet/dry and/or freeze-thaw weight loss (when applicable).

In addition, where applicable, the Contractor shall submit for approval
by the Engineer a jointing plan for transverse joints in the econocrete
layer.

During production, the Contractor shall submit batch tickets for each
delivered load.

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> Insert the appropriate number of days for Contractor submittal of the
> certified test reports and the mix design; 15 to 30 days is typical.
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# 

#### EQUIPMENT

**306-4.1** All equipment necessary to mix, transport, place, compact,
and finish the econocrete material shall be furnished by the Contractor.
The equipment shall be subject to inspection and approval by the
Engineer.

**306-4.2 MIXING.** Econocrete may be mixed in a stationary mixer,
either at a central batch plant or at the site, or in a truck mixer. The
mixer type and capacity shall be inspected and approved by the Engineer
before production begins. Each mixer shall have attached in a prominent
place a manufacturer\'s nameplate showing the capacity of the drum in
terms of volume of mixed concrete and the speed of rotation of the
mixing drum or blades.

306-4.2.1 Stationary Plant Mixer***.*** The batch plant and equipment
shall conform to the requirements of ASTM C 94. Unrestricted access to
the plant must be provided to the Engineer at all times for inspection
of the plant's equipment and operation and for sampling the econocrete
mixture and its components.

The mixers shall be examined daily for changes in condition due to
accumulation of hard concrete or mortar or wear of blades.

**306-4.2.2 Truck Mixers***.* Truck mixers used for mixing econocrete
shall conform to the requirements of ASTM C 94. Econocrete may be
entirely mixed in a truck mixer or partially mixed in a stationary mixer
with mixing completed in a truck mixer. Truck mixers shall be equipped
with an accurate continuous registering electronically or mechanically
activated revolution counter, by which the number of drum revolutions
may be verified.

**306-4.3 HAULING.** Mixed econocrete shall be hauled from the
stationary plant to the job site in a truck agitator, a truck mixer
operating at agitating speed, or a non-agitating truck. All equipment
shall conform to the requirements of ASTM C 94. When truck mixers are
used to mix econocrete, they may be transported to the job site in the
same truck operating at agitating speeds, truck agitators, or a
non-agitating truck. The bodies of non-agitating trucks shall be smooth,
metal containers and shall be capable of discharging the concrete at a
satisfactory controlled rate without segregation.

**306-4.4 PLACING AND FINISHING**.

**306-4.1 Forms.** Straight side forms shall be made of steel and shall
be furnished in sections not less than 10 ft (3.1 m) in length. Forms
shall have a depth equal to the pavement thickness at the edge. Flexible
or curved forms of proper radius shall be used for curves of 100-ft
(31-m) radius or less. Forms shall be provided with adequate devices for
secure settings so that when in place they will withstand, without
visible spring or settlement, the impact and vibration of the
consolidating and finishing equipment. Forms with battered top surfaces
and bent, twisted or broken forms shall not be used. Built-up forms
shall not be used, except as approved by the Engineer.

The top face of the form shall not vary from a true plane more than ⅛ in
(3 mm) in 10 ft (3.1 m), and the upstanding leg shall not vary more than
¼ in (6 mm). The forms shall contain provisions for locking the ends of
abutting sections together tightly for secure setting. Wood forms may be
used under special conditions, when accepted by the Engineer.

**306-4.4.2 Pavers.** Econocrete can be placed using fixed forms or
slip-form pavers. The paver shall be fully energized, self-propelled and
capable of spreading, consolidating, and finishing the econocrete
material, true to grade, tolerances, and cross sections. The paver shall
be capable of finishing the surface so that hand finishing is not
required. The paver shall be of sufficient weight and power to construct
the maximum specified concrete paving lane width, at adequate forward
speed, without transverse, longitudinal or vertical instability or
without displacement. The slip-form paver shall be equipped with
electronic or hydraulic horizontal and vertical control devises
utilizing guide wires or stringlines on both sides of the machine. Slope
control will not be allowed.

a.  Concrete Pavers. Concrete pavers are approved as paver-finishing
    machines for econocrete, providing they are capable of handling the
    amount of econocrete required for the full-lane width specified, and
    consolidating the econocrete full depth. A concrete paver is a
    power-driven machine with augers, strike-off and tamper bars ahead
    of a pan screed, with at least one trailing oscillating screed or
    belt finisher.

b.  Bridge Deck Pavers. Bridge deck pavers are approved as
    paver-finishing machines for econocrete, providing they are capable
    of handling the amount of econocrete required for the full-lane
    width specified, and consolidating the econocrete full depth. A
    bridge deck paver is an automatic truss paving machine, with paving
    carriage that strikes off, vibrates, paves, and textures the
    econocrete with augers, internal vibration, paving rollers, and drag
    pan.

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> Econocrete is a weak concrete mix. As such, it should be placed with
> pavers suitable for paving concrete pavements. Rotating pipe and tube
> floats are not suitable for this type of pavement.
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**306-4.5 CONSOLIDATION**. For side-form construction, vibrators may be
either the surface pan type for pavements less than 8 in (203 mm) thick
or the internal type with either immersed tube or multiple spuds for the
full width of the slab. They may be attached to the spreader or the
finishing machine, or they may be mounted on a separate carriage. They
shall not come in contact with the joint, subgrade, or side forms.

For slip-form construction, the paver shall vibrate the econocrete for
the full width and depth of the strip of pavement being placed.
Vibration shall be accomplished by internal vibrators.

The number, spacing, frequency, and eccentric weights of vibrators shall
be provided as necessary to achieve acceptable consolidation without
segregation and finishing quality. Adequate power to operate all
vibrators at the weight and frequency required for a satisfactory finish
shall be available on the paver. The internal vibrators may be
supplemented by vibrating screeds operating on the surface of the
econocrete. The Contractor shall constantly monitor the frequency of
each of the individual vibrators using electronic means and shall
provide constant monitoring of the consolidation process to avoid
honeycombing or segregation. Areas that are visually determined to be
honeycombed or over-consolidated shall be corrected at the Contractor's
expense.

The vibrators and tamping elements shall be automatically controlled so
that they stop operation as forward motion ceases. Any override switch
shall be of the spring-loaded, momentary-contact type.

Hand held vibrators may be used in irregular areas.

**306-4.6 JOINTING.** The Contractor shall provide sawing equipment
adequate in number of units and power to produce contraction or
construction joints of the required dimensions as shown on the plans.
The Contractor shall provide at least one standby saw in good working
order and a supply of saw blades at the site of the work at all times
during sawing operations.

#### CONSTRUCTION METHODS

306-5.1 WEATHER LIMITATIONS.

**306-5.1.1 Cold Weather***.* Unless authorized by the Engineer, the
temperature of the mixed econocrete shall not be less than 50°F (10°C)
at the time of placement. In addition, the econocrete shall not be
placed when the ambient temperature is below 40°F (4°C) or when
conditions indicate that the temperature may fall below 35°F (2°C)
within 24 hours. Under no circumstances shall the econocrete be placed
on frozen underlying courses or mixed when the aggregate is frozen.

When mixing and placing is authorized during cold weather, the Engineer
may require the water and/or the aggregates to be heated to not less
than 70°F (20°C) nor more than 150°F (66°C). The aggregates may be
heated by either steam or dry heat prior to being placed in the mixer.
The apparatus used shall heat the mass uniformly and shall be arranged
to preclude the possible occurrence of overheated areas which might be
detrimental to the materials.

**306-5.1.2 Hot Weather***.* To prevent rapid drying of newly
constructed econocrete, the econocrete temperature from initial mixing
through final cure shall not exceed 90°F (32°C). The aggregates and/or
mixing water shall be cooled as necessary to maintain the econocrete
temperature at or not more than the specified maximum. Ice or ice water
may be substituted for the mixing water for this purpose.

In addition, during periods of warm weather when the maximum daily air
temperature exceeds 85°F (30°C), the forms and/or the underlying
material shall be sprinkled with water immediately before placing the
econocrete.

**306-5.1.3 Rain***.* All mixing and batching operations should be
halted during rain showers and any plastic econocrete placed should be
covered immediately. The econocrete shall be kept covered with plastic
sheeting or other waterproof material until such time that the rain does
not make any surface indentation on the econocrete layer. Areas damaged
by rain shall be refinished or replaced.

**306-5.2 FORM SETTING**. Forms shall be set sufficiently in advance of
the econocrete placement to ensure continuous paving operation. After
the forms have been set to correct grade, the grade shall be thoroughly
tamped, either mechanically or by hand, at both the inside and outside
edges of the base of the forms. Forms shall be staked into place with
not less than 3 pins for each 10-ft (3.1-m) section. A pin shall be
placed at each side of every joint.

Form sections shall be tightly locked and shall be free from play or
movement in any direction. The forms shall not deviate from true line by
more than ¼ in (6 mm) at any joint. Forms shall be so set that they will
withstand, without visible spring or settlement, the impact and
vibration of the consolidating and finishing equipment. Forms shall be
cleaned and oiled prior to the placing of econocrete.

The alignment and grade elevations of the forms shall be checked and
corrections made by the Contractor immediately before placing the
econocrete. When any form has been disturbed or any grade has become
unstable, the form shall be reset and rechecked.

**306-5.3 PREPARATION OF UNDERLYING COURSE**. The underlying course
shall be checked by the Engineer before placing and spreading operations
are started, in order to ensure that it is free of any ruts,
depressions, or bumps and is finished to the correct grade. Any ruts or
soft yielding places in the underlying course caused by improper
drainage conditions, hauling, or any other cause, shall be corrected at
the Contractor's expense before the econocrete mixture is placed
thereon. The underlying course should be wetted down in advance of
placing the econocrete to ensure a firm, moist condition at the time of
econocrete placement. The underlying course shall be protected from
frost. Usage of chemicals to eliminate frost is not permissible.

**306-5.4 GRADE CONTROL**. Grade control between the edges of the
pavement shall be accomplished at intervals of 50 ft (15.3 m) or less on
the longitudinal grade and at 25 ft (7.6 m) or less on the transverse
grade. To protect the underlying course and ensure proper drainage, the
econocrete paving shall begin along the centerline of the pavement on a
crowned section or on the greatest contour elevation of a pavement with
variable cross slope.

**306-5.5 HANDLING, MEASURING, AND BATCHING MATERIAL.** The batch plant
site, layout, equipment, and provisions for transporting material shall
assure a

continuous supply of material to the work. Stockpiles shall be
constructed in a manner that prevents segregation and intermixing of
deleterious materials.

Aggregates that have become segregated or mixed with earth or foreign
material shall not be used. All aggregates produced or handled by
hydraulic methods, and washed aggregates, shall be stockpiled or binned
for draining at least 12 hours before being batched. Rail shipments
requiring more than 12 hours transit will be accepted as adequate
binning only if the car bodies permit free drainage.

Batching plants shall be equipped to proportion aggregates and bulk
cement, by weight, automatically using interlocked proportioning devised
of an approved type. When bulk cement is used, the Contractor shall use
a suitable method of handling the cement from weighing hopper to
transporting container or into the batch itself for transportation to
the mixer, such as a chute, boot or other device approved by the
Engineer, to prevent loss of cement. The device shall be arranged to
provide positive assurance that the required cement content is present
in each batch.

**306-5.6 MIXING.** All econocrete shall be mixed and delivered to the
site in accordance with the requirements of ASTM C 94. The mixing time
should be adequate to produce econocrete that is uniform in appearance,
with all ingredients evenly distributed. Mixing time shall be measured
from the time all materials are emptied into the drum (provided all the
water is added before one-fourth the preset mixing time has elapsed) and
continues until the time the discharge chute is opened to deliver the
econocrete.

If mixing in a plant, the mixing time shall not be less than 50 nor
greater than 90 seconds. If mixing in a truck, the mixing time shall not
be less than 70 nor more than 125 truck-drum revolutions at a mixing
speed of not less than 6 nor more than 18 truck-drum revolutions per
minute.

Retempering econocrete by adding water or by other means will not be
permitted, except when econocrete is delivered in truck mixers. With
truck mixers, additional water may be added to the batch materials and
additional mixing performed to allow proper placement of the material,
provided (a) the addition of water is performed within 45 minutes after
the initial mixing operations and (b) the water/cementitious ratio
specified in the mix design is not exceeded.

**306-5.7 HAULING**. The elapsed time from the addition of cementitious
material to the mix until the econocrete is deposited in place at the
work site shall not exceed 45 minutes when the concrete is hauled in
nonagitating trucks, nor 90 minutes when it is hauled in truck mixers or
truck agitators.

**306-5.8 PLACING, CONSOLIDATING, AND FINISHING.** Prior to placement of
the econocrete layer, the prepared underlying course shall be well
moistened with water, without saturating, in order to prevent rapid loss
of moisture from the econocrete. In cold weather, the underlying course
shall be protected so that it will be entirely free of frost when
econocrete is placed.

The Contractor has the option of side- (fixed-) form or slip-form
paving. Under both techniques, the hauled econocrete material shall be
discharged onto the prepared underlying course such that segregation of
the mix is minimized and minimum handling of the mix is needed.
Placement of the econocrete material shall be continuous between
construction joints. Workers shall not be allowed to walk in the freshly
mixed econocrete with boots or shoes coated with earth or debris.

Econocrete shall not be mixed, placed, or finished when the natural
light is insufficient, unless an adequate artificial lighting system is
provided.

**306-5.8.1 Side-Form Construction[.]{.underline}** For side-form
placement, the Contractor shall verify the elevations of the fixed forms
such that the thickness and finished grade of the econocrete layer will
be in accordance with the requirements of the project plans and
specifications. The econocrete shall be spread uniformly between the
forms, immediately after it is placed using a spreading machine.
Necessary hand spreading shall be done with shovels, not rakes.

The spreading shall be followed immediately by thorough consolidation
using vibrating screeds or spud vibrators. Vibrators may be external or
internal type, depending on the thickness of the econocrete layer. The
surface vibrators may be attached to the spreader or they may be mounted
on a separate carriage. They shall not come in contact with the joint,
subgrade, or side forms. When spud vibrators are used, the econocrete
shall be thoroughly consolidated against and along the faces of all
forms and previously placed econocrete. Vibrators shall not be permitted
to come in contact with a joint assembly, the grade, or a side form. In
no case shall the vibrator be operated longer than 20 seconds in any one
location, nor shall the vibrators be used to move the econocrete.

Hand finishing will not be permitted except in areas where the
mechanical finisher cannot operate.

**306-5.8.2 Slip-Form Construction.** For slip-form construction, the
Contractor shall verify the elevations of the guide wires controlling
slip-form pavers such that the thickness and finished grade of the
econocrete will be in accordance with the requirements of the project
plans and specifications. The slip-form paver should spread,
consolidate, and shape the freshly placed econocrete in one complete
pass of the machine. The machine shall vibrate and finish the econocrete
for the full width and depth of the layer.

**306-5.9 Final Finishing**. Final finishing shall be accomplished while
the econocrete is still in the plastic state. Limited surface
refinishing by hand is acceptable to meet the grade and surface
tolerance established in paragraphs 306-6.2.3 and 306-6.2.4, after
strike off and consolidation.

If the overlying layer is to be PCC pavement, the surface of the
econocrete shall not be textured. If the overlying layer is to be HMA
pavement, and if the bond between the HMA layer and the econocrete is
considered important for pavement performance, tining or scarifying the
surface to provide a coarse texture may be permitted.

**306-5.10 JOINTS**. Joints shall be constructed as shown on the plans.

**306-5.10.1 Construction Joints***[.]{.underline}* Locate all
longitudinal and transverse construction joints as shown on the plans.
If longitudinal joints are not shown, locate longitudinal joints within
6 in (152 mm) from planned joints in the PCC to be placed over the
econocrete.

**306-5.10.2 Contraction Joints**. If required by paragraph306-3.1.1or
if shown on the plans, transverse contraction joints shall be
constructed by sawing the hardened econocrete to a depth of at least
one-third the thickness of the econocrete base. These joints shall match
within 3 in (76 mm) the planned joints of the overlying concrete
surface.

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The Engineer should include a note or detail on the plans when joints
are required due to excessive strength or otherwise.

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**306-5.10.3 Concrete Saws.** When sawing of joints are specified, the
Contractor shall provide sawing equipment adequate in number of units
and power to complete the sawing to the required dimensions and at the
required rate. The Contractor shall provide at least one standby saw in
good working order. An ample supply of saw blades shall be maintained at
the site of the work at all times during sawing operations. The
Contractor shall provide adequate artificial lighting facilities for
night sawing. All of this equipment shall be on the job both before and
at all times during econocrete placement.

**306-5.11 CURING**. Immediately after the finishing operations are
complete and within 2 hours of placement of the econocrete, the entire
surface and edges of the newly placed econocrete shall be sprayed
uniformly with white pigmented, liquid membrane forming curing compound.
The layer should be kept moist using a moisture-retaining cover or a
light application of water until the curing material is applied. The
curing compound shall not be applied during rainfall.

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> Excessive delays in applying the curing compound can result in
> uncontrolled shrinkage cracking, which can reflect into the overlying
> pavement over time.
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The curing material shall be applied using mechanical sprayers under
pressure at the rate of 1 gal (3.8 L) to not more than 200 ft^2^ (18.6
m^2^). The spraying equipment shall be of the fully atomizing type
equipped with a tank agitator. At the time of use, the compound in the
tank shall be in a thoroughly mixed condition with the pigment uniformly
distributed throughout the vehicle. During application the compound
shall be stirred continuously by mechanical means.

Hand spraying of odd widths or shapes and econocrete surfaces exposed by
the removal of forms is permitted.

Should the film of curing material become damaged from any cause,
including sawing operations, within the required 28-day curing period or
until the overlying course is constructed, the damaged portions shall be
repaired immediately with additional compound or other approved means as
quickly as practical.

Edges of the econocrete layer shall be sprayed with curing compound
immediately following placement with slip-form pavers or when side-forms
are removed.

**306-5.11.1 Curing in Cold Weather**. The econocrete shall be
maintained at a temperature of at least 50°F (10°C) for a period of 72
hours after placing and at a temperature above freezing for the
remainder of the curing time. The Contractor shall be responsible for
the quality and strength of the econocrete placed during cold weather,
and any econocrete injured by frost action shall be removed and replaced
at the Contractor\'s expense.

**306-5.11.2 Curing in Hot Weather.** When econocrete is being placed
and the air temperature may be expected to rise above 90°F (32°C)
shortly after placement, the econocrete layer should be cured as quickly
as possible to allow curing without the formation of excessive shrinkage
cracks.

**306-5.12 PROTECTION**. The Contractor shall protect the pavement and
its appurtenances against both public traffic and traffic caused by the
Contractor's employees and agents. The Engineer shall decide when the
pavement shall be opened to traffic. Traffic shall not be allowed on the
pavement until test specimens molded and cured in accordance with ASTM C
31 have attained a compressive strength of 350 psi (2,413 kPa) when
tested by ASTM C 39. The econocrete surface shall be protected from foot
and vehicular traffic and other sources of abrasion until such a time.
During this time, the econocrete layer shall be protected from injurious
action by sun, rain, flowing water, frost, or mechanical injury. After
this period, construction traffic to place the overlying layers may be
allowed.

**306-5.13 BOND-BREAKER**. When the econocrete is to be placed directly
beneath PCC pavement, a bond-breaker shall be used. The entire surface
of the econoncrete shall be coated with a de-bonding compound applied in
a quality sufficient to prevent bonding of the PCC pavement to the
econocrete. If an impervious membrane or asphalt emulsion is used as a
curing material, additional applications of curing materials may be
required. The Contractor shall be responsible for selecting the
de-bonding compound and determining the necessary application rate. The
de-bonding compound shall be approved by the Engineer prior to being
incorporated into the work. This application shall be made at least 8
hours and not more than 24 hours prior to beginning the placement of the
PCC pavement. The rate of application shall be the same as that
specified for the curing application. After application of the
bond-breaker coat, traffic will be limited to that required for the
placement of the overlying pavement layer.

[]{.mark}

#### MATERIAL ACCEPTANCE

**306-6.1 ACCEPTANCE SAMPLING AND TESTING.** All acceptance sampling and

testing, with the exception of coring for thickness determination,
necessary to determine conformance with the requirements specified in
this section will be performed by the Engineer. The Contractor shall
provide the required econocrete samples during construction for
acceptance testing purposes. The samples shall be taken in the presence
of the Engineer.

The econocrete layer shall be tested for air content, strength,
thickness, grade, and surface tolerance. Sampling and testing for air
shall be as specified in paragraph 306-6.1.1. Sampling and testing for
strength, thickness, grade, and surface tolerance shall be on a lot
basis, with a lot consisting of one of the following:

-   One day's production not to exceed 2,000 yd^2^ (1,675 m^2^).

-   A half day's production, where a day's production is expected to
    consist of between 2,000 and 4,000 yd^2^ (1,675 and 3,350 m^2^).

Each lot will be divided into four equal sublots. In the event that only
three (3) sublots are produced, the three sublots shall constitute a
complete lot. If, only one (1) or two (2) sublots are produced, they
shall be incorporated into the next lot, and the total number of sublots
shall be used in the acceptance plan calculation.

End-of-production sublots (i.e., sublots associated with the final
placement of econocrete for the project and are less than a complete
lot) shall be handled as:

-   Three (3) sublots shall constitute a lot.

-   One (1) or (2) sublots shall be incorporated into the previous lot.

**306-6.1.1 Air Content Testing**. Air content tests shall be performed
on the first three truckloads of econocrete produced at the start of
operations each day and the first three truckloads produced after any
scheduled or non-scheduled shutdown. Additional tests shall be performed
each time a sample is taken for a strength test and when requested by
the Engineer.

Air content tests shall be made in accordance with ASTM C 231. Air
content test results shall be between 4 and 8 percent.

If the first test on a truckload of econocrete is not within the
specification limits, a second test on the same truckload shall be made.
If the second test is within the specification limits, the econocrete
will be accepted with respect to entrained air content. If the second
test is not within the specification limits, the truckload shall be
rejected.

**306-6.1.2 Compressive Strength Testing***.* One sample of freshly
delivered econocrete shall be taken from each sublot for compressive
strength testing. The econocrete shall be sampled in accordance with
ASTM C 172. Sampling locations shall be determined in accordance with
the random sampling procedures contained in ASTM D 3665.

At least two (2) test cylinders shall be made from each sample in
accordance with ASTM C 31. The 7-day compressive strength of each
cylinder shall be determined in accordance with ASTM C 39.

> \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \*
> \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \*
>
> Since the strength level of econocrete at an early age is considerably
> lower than PCC, special care is required in handling test specimens.
>
> \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \*
> \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \* \*

The Contractor shall provide adequate facilities for the initial curing
of cylinders. During the 24 hours after molding, the temperature
immediately adjacent to the specimens must be maintained in the range of
60 to 80°F (16 to 27°C), and loss of moisture from the specimens must be
prevented. The specimens may be stored in tightly constructed wooden
boxes, damp sand pits, temporary buildings at construction sites, under
wet burlap in favorable weather or in heavyweight closed plastic bags,
or use other suitable methods, provided the temperature and moisture
loss requirements are met.

The compressive strength for each sublot shall be computed by averaging
the 7-day compressive strengths of the two test cylinders representing
that sublot. The compressive strength of the lot shall be the average
compressive strength of the individual sublots comprising the lot.

Specimens that are noticeably defective shall not be considered in the
determination of the strength. If the test specimens fail to conform to
the requirements for strength, the Engineer shall request changes in the
econocrete mixture to increase the strength to meet the requirements.

If the maximum 7-day compressive strength values exceed the maximum
strength requirements when evaluated in accordance with paragraph
306-6-2.1, the Contractor shall propose a jointing plan for approval by
the Engineer.

**306-6.1.3 Thickness Testing.** After the econocrete base has cured for
3 days, one (1) 4-in (102-mm) diameter core per sublot shall be obtained
from a random location, as identified using the procedures contained in
ASTM D 3665. The thickness of each sampled core shall be determined
using the caliper measurement procedures provided by ASTM C 174. The
average thickness for the lot shall be determined using the individual
sublot core thicknesses. Acceptance criteria for econocrete thickness
are provided in paragraph 306-6.2.2.

When such measurement is deficient more than ½ in (12.5 mm) and not more
than 1 in (25.4 mm) from the plan thickness, two additional cores shall
be taken at random and used in determining the average thickness for
that lot. The thickness of the cores shall be determined by average
caliper measurement of cores tested in accordance with ASTM C 174.

At all locations where cores have been drilled, the resulting holes
shall be filled with econocrete or non-shrink grout material, as
approved by the Engineer.

**306-6.1.4 Grade Testing.** The elevations of the finished econocrete
shall be surveyed on both sides of the econocrete lane, every 25 ft (7.6
m).

**306-6.1.5 Surface Tolerance Testing.** After the econocrete has
hardened sufficiently, it shall be tested for surface tolerance with a
16-ft (4.9-m) straightedge provided by the Contractor.

**306-6.2 ACCEPTANCE CRITERIA.** Acceptance of econocrete will be based
on compressive strength, thickness, grade, and surface tolerance, as
described in the paragraphs below.

***306-6.2.1 Compressive Strength Requirements*.** The econocrete shall
meet all of the following compressive strength requirements on a lot
basis:

-   The compressive strength of the lot, tested at 7 days, shall be
    greater than 500 psi (3,445 kPa). When a given lot of econocrete
    fails to meet the minimum compressive strength requirements, the
    entire lot shall be replaced at the Contractor's expense.

-   Not more than 20 percent of the individual cylinders in a given lot,
    tested at 7 days, shall have a compressive strength greater than 800
    psi (5,512 kPa). When greater than 20 percent of the individual
    cylinders in a given lot have 7-day compressive strengths in excess
    of 800 psi (5,512 kPa), and transverse joints have not been
    constructed, a bond-breaker shall be used.

**306-6.2.2 Thickness Requirements.** The completed thickness shall be
as shown on the plans. When the average lot thickness is not deficient
by more than ½ in (12.5 mm) from the plan thickness, full payment shall
be made. If the lot average thickness is deficient by more than 1 in
(25.4 mm), it shall be removed and replaced at the Contractor's expense.
When such measurement is deficient more than ½ in (12.5 mm) and not more
than 1 in (25.4 mm) from the plan thickness, one additional core shall
be taken at random from each sublot within the lot. The thickness of
these additional cores shall be determined as indicated in paragraph
304-6.1.2. A new lot average thickness shall be recomputed based on
these additional cores and the original cores taken from each sublot.
When the recomputed average lot thickness is not deficient by more than
½ in (12.5 mm) from the plan thickness, full payment shall be made. If
the average lot thickness is deficient by more than ½ in (12.5 mm) from
the plan thickness, the entire lot shall be removed and replaced at the
Contractor\'s expense or shall be permitted to remain in place at an
adjusted payment of 75 percent of the contract unit price.

When the measured thickness is more than that indicated on the plans, it
will be considered as conforming to the requirements, provided the
surface of the completed econocrete layer is within the established
grade and surface tolerance requirements.

**306-6.2.3 Grade Requirements**. When the completed surface is more
than ½ in (12.5 mm) above the grade shown in the plans, the surface
shall be trimmed at the Contractor's expense using an approved grinding
machine to an elevation that falls within a tolerance of ¼ in (6 mm).
The ground surface shall be sprayed with curing compound at double the
rate specified prior to paving.

**306-6.2.4 Surface Tolerance Requirements.** Surface deviations shall
not exceed ⅜ in (9.5 mm) from a 16-ft (4.9-m) straightedge laid in any
location parallel with or at right angles to the longitudinal axis of
the centerline (includes along all edges of the paving lane). Any high
spots of more than ⅜ in (9.5 mm) in 16 ft (4.9 m) shall be marked and
immediately trimmed with an approved grinding machine. If the overlying
layer is PCC pavement, the ground surface shall be sprayed with a double
application of the curing compound at the specified rate prior to
paving.

#### METHOD OF MEASUREMENT

**306-7.1** The quantity of econocrete to be paid for will be determined
by the number of \[yd^2^ (m^2^)\] of econocrete actually constructed and
accepted by the Engineer as complying with the plans and specifications.

#### BASIS OF PAYMENT

**306-8.1** The accepted quantities of econocrete will be paid for at
the contract unit price per \[yd^2^ (m^2^)\] for econocrete base. The
price and payment shall be full compensation for furnishing and placing
all materials, provided; however, for any pavement found deficient in
thickness as specified in paragraph 306-6.2.2, the reduced unit price
shall be paid.

Payment will be made for econocrete base course\--per \[yd^2^ (m^2^)\].

#### TESTING REQUIREMENTS

ASTM C 31 Making and Curing Concrete Test Specimens in the Field

ASTM C 39 Compressive Strength of Cylindrical Concrete Specimens

ASTM C 136 Sieve or Screen Analysis of Fine and Course Aggregates

ASTM C 172 Sampling Freshly Mixed Concrete

ASTM C 173 Air Content of Freshly Mixed Concrete by the Volumetric
Method

ASTM C 174 Measuring Length of Drilled Concrete Cores

ASTM C 192 Making and Curing Concrete Test Specimens in the Laboratory

ASTM C 231 Air Content of Freshly Mixed Concrete by the Pressure Method

ASTM D 560 Standard Test Methods for Freezing and Thawing Compacted
Soil-Cement Mixtures

ASTM D 3665 Random Sampling of Paving Materials

AASHTO T 26 Quality of Water to be Used in Concrete

#### MATERIAL REQUIREMENTS

ASTM C 33 Specification for Concrete Aggregates

ASTM C 94 Specification for Ready-Mixed Concrete

ASTM C 150 Specification for Portland Cement

ASTM C 260 Specification for Air-Entraining Admixtures for Concrete

ASTM C 309 Specification for Liquid Membrane-Forming Compounds for
Curing Concrete

ASTM C 494 Specification for Chemical Admixtures for Concrete

ASTM C 595 Standard Specification for Blended Hydraulic Cements

ASTM C 618 Specification for Fly Ash and Raw and Calcined Natural
Pozzolans for Use in Portland Cement Concrete

# 

ASTM C 989 Standard Specification for Ground Granulated Blast-Furnace
Slag for Use in Concrete and Mortars

### END P-306