Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 2 - ROAD STRUCTURES, 2020)

This chapter defines standards and requirements for the construction of drilled foundation piles, with
or without bell footings, including the placement of reinforcing steel and concrete. All such work shall
comply with the contractual requirements for the Project and the specifications outlined in this
chapter.

17.1

Reference Standards and Codes

Standards and codes for Drilled Piles shall be as specified in these specifications, in the Contract
documents, if any, and the following, in their latest edition:

•

AASHTO LRFD

American Association of State Highway and Transportation Officials -

Load and Resistance Factor Design, Bridge Construction Specifications;

•

AASHTO LRFD

American Association of State Highway and Transportation Officials -

Load and Resistance Factor Design, Bridge Design Specifications;

•

AASHTO

Standard Specifications for Transportation Materials and Methods of

Sampling and Testing;

•

ADQCC (TR-516)

Road Structures Design Manual;

•

API

American Petroleum Institute;

•

ASTM American Society for Testing and Materials.

Table 17-1 presents AASHTO and American Society for Testing and Materials (ASTM) standards
that are related to materials for drilled piles. It includes designations and titles.

Table 17-1: Designations and titles for AASHTO and ASTM standards that apply to drilled

piles works

AASHTO
DESIGNATION

ASTM
DESIGNATION

TITLE

ASTM D4380-12

Standard Test Method for Density of Bentonitic
Slurries

ASTM
D6910/D6910M-09

Standard Test Method for Marsh Funnel Viscosity
of Clay Construction Slurries

ASTM
D4381/D4381M-12

Standard Test Method for Sand Content by Volume
of Bentonitic Slurries

ASTM
D1143/D1143M-
07e1

Standard Test Methods for Deep Foundations
Under Static Axial Compressive Load

ASTM D3689-07

Standard Test Methods for Deep Foundations
Under Static Axial Tensile Load

ASTM D3966-07

Standard Test Methods for Piles Under Lateral
Loads

ASTM D5882-07

Standard Test Method for Low Strain Impact
Integrity Testing of Deep Foundations

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AASHTO
DESIGNATION

ASTM
DESIGNATION

TITLE

ASTM D6760-08

Standard Test Method for Integrity Testing of
Concrete

Deep

Foundations

Ultrasonic

Crosshole Testing

ASTM D4945-12

Standard Test Method for High-Strain Dynamic
Testing of Deep Foundations

17.2

Working Drawings

When required by the Contract documents, at least four weeks before work on piles is to begin, the
Contractor shall submit to the Engineer for review and approval, an installation plan for the
construction of drilled piles. The submittal shall include the following:

a. List of proposed equipment to be used, including cranes, drills, augers, bailing buckets, final

cleaning equipment, desanding equipment, slurry pumps, sampling equipment, tremies or
concrete pumps, casings, etc.

b. Details of overall construction operation sequence and the sequence of piles construction in

bents or groups.

c.  Details of pile drilling methods.
d.  When slurry is required, details of the method proposed to mix, circulate, and desand slurry.
e.  Details of methods to clean the pile drilling.
f.  Details of reinforcement placement, including support and centralization methods.
g.  Details of concrete placement, curing, and protection.
h.  Details of any required load tests.
i.  Other information shown in the contract documents or requested by the Engineer.

The Contractor shall not start the construction of drilled piles for which working drawings are required
until such drawings have been approved by the Engineer.

Such approval will not relieve the Contractor of responsibility for results obtained by use of these
drawings or any of the Contractor's other responsibilities under the Contract documents.

17.3

Ground Investigation

The Contractor shall investigate the Project site to a depth sufficient to identify all ground formations
and layers that affect pile construction and to recognize the capacity and deformation properties of
the ground. In accordance with the Project requirements, a site investigation shall determine the
P

roject site’s characteristic ground conditions.

If the maintenance of stability of pile bore is likely to be difficult, the Contractor shall complete a trial
bore of relevant dimensions. To determine the extent of a ground investigation, the Contractor shall
consider their own experience and available information that is relevant to the execution of
comparable foundation works under similar conditions and within the general vicinity of the Project
site.

The Contractor shall backfill all boreholes sufficiently to ensure that subsequent pile construction
and performance are not affected.

A number of test piles as defined in the Contract Documents shall be constructed and load tested
before permanent construction.

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17.4

Piling Method and Programme

The Contractor shall supply for approval all relevant details of the proposed method of piling and
plant use. Any method other than that specified in the Contract documents shall be subject to
approval by the Engineer.

Every  day,  the  Contractor  shall  inform  the  Engineer  of  the  intended  programme  for  piling  for  the
following  day  and  shall  give  adequate  notice  of  intentions  to  work  outside  normal  hours  or  on
holidays. The Contractor shall submit to the Engineer a proposed sequence and timing for boring
piles. Such schedules shall ensure that boring does not damage adjacent piles.

17.5

Ensuring Safety when Drilling Piles

The Contractor shall comply with the requirements outlined in this section

and the Owner’s

Environmental, Health and Safety procedures to ensure that drilling operations and drilled foundation
piles are safe.

17.5.1

General Safety Requirements for Drilled Piles

A competent person who is properly qualified and experienced, on behalf of the Contractor, shall
supervise all piling operations. This person shall be capable of responding to and assessing any
potential dangers, such as unexpected ground conditions that may require different construction
techniques or unusual smells that may indicate the presence of noxious or dangerous gases.

17.5.2

Life-saving Appliances

The Contractor shall provide sufficient, proper, and effective life-saving appliances of types and
natures that have the Engineer

’s approval. Such appliances shall be conspicuous on the Project site

and shall be available at all times for possible use.

At least one site operative shall be instructed in the use of such safety equipment and shall
participate in periodic drills to ensure that any such operative can correctly observe all necessary
procedures.

17.6

Avoiding Disturbances and Damage when Drilling
Piles

The Contractor shall ensure that foundation pile drilling is not a nuisance and does not cause damage
to adjacent structures or piles.

17.6.1

Reducing Noises and Disturbances from Pile Drilling

When working, the Contractor shall keep noises, vibrations, and other disturbances to a minimum
and shall comply with all current environmental legislation, as applicable, particularly in urban areas.
The Contractor shall understand the nature and levels of noise produced by mechanical equipment
they use and take appropriate steps, as possible, to reduce noise levels and annoying
characteristics.

17.6.2

Avoiding Damage to Adjacent Structures

If the Contractor believes that pile drilling is likely to damage mains, services, or adjacent structures,
they shall submit proposals for conducting preconstruction surveys, monitoring movements or
vibrations, and minimizing or avoiding such damage to the Engineer for review and approval.

17.6.3

Avoiding Damage to Piles

The Contractor shall ensure that pile drilling does not cause displacement or damage that could
impair either performance or durability of completed piles. The Contractor shall submit to the

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Engineer a proposed sequence and timing for drilling piles, including plans and methods to avoid
damaging adjacent piles.

17.7

Obstructions

When unexpected manmade materials prevent the Contractor from advancing an excavation,  the
Contractor shall remove such manmade obstructions after notifying the Engineer and explaining the
proposed  method  for  removal.  If  the  Contractor  seeks  additional  compensation  to  remove  such
obstructions, the Contractor must also provide a cost estimate to the Engineer. The Contractor shall
not remove any obstructions without approval from the Engineer, including specific approval for the
proposed method for removal.

The Owner does not consider naturally-occurring material, regardless of difficulty or removal method,
to be an obstruction. The Contractor shall remove all such naturally-occurring impediments at their
own expense as part of the pile drilling activity.

The Owner does not consider the removal of tools that the Contractor loses in an excavation to be
an obstruction. The Contractor shall promptly remove all such tools from the excavation at their own
expense. The Contractor is responsible for all costs for the removal of lost tool, including costs to
correct hole degradation that result from removal operations and any associated time delays.

17.8

Pile Construction Record

The Contractor shall keep records, as outlined in this section, for the installation of each pile and
shall submit two signed copies of these records to the Engineer no later than noon of the next working
day after the pile was installed. Such signed documents constitute a historical and legal record of
the work.

The Contractor shall note any unexpected boring conditions in these records.

Pile construction records shall include the following data:

•

The Contract

•

Pile reference number (location)

•

Pile type

•

Nominal cross sectional dimensions or diameter

•

Nominal diameter of underream or base

•

Standing groundwater level from direct observation or given site investigation data

•

Date and time of boring

•

Date of concreting

•

Ground level at pile position upon commencement of pile installation.

•

Working level on which piling base machine stands

•

Depth from ground level at pile position to pile toe level

•

Toe level

•

Pile head level, as constructed

•

Pile cut-off level

•

Length of temporary casing

•

Length of permanent casing

•

Soil samples taken and in situ tests carried out during pile formation or adjacent to piles

•

Length and details of reinforcement

•

Type of concrete mix (materials and composition)

•

Volume of concrete supplied to pile (where this can be measured)

•

All information regarding obstruction delays and other interruptions to the sequence of work

•

Integrity testing (whether this is low or high frequency)

•

Verticality and tolerance achieved

•

Treatment of pile base to minimise contamination

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17.9

Construction Tolerances

The Contractor shall maintain the following tolerances when constructing drilled piles:

a. A drilled pile shall be within 75 mm of its planned position in the horizontal plane at the plan

elevation for the top of the pile.

A pile excavation’s vertical alignment shall not vary from its planned alignment by more than
1 in 75.

c. After placement of all the pile concrete, the top of a reinforcing steel cage shall be no more

than 150 mm above and no more than 75 mm below its planned position.

d. Casing, when used, shall have an outside diameter not less than the pile diameter shown in

the Contract documents. When casing is not used, the minimum diameter for a drilled pile
with a diameter of 600 mm or less shall exactly match the diameter shown in the Contract
documents, whereas drilled piles with diameters greater than 600 mm shall have diameters
that are no smaller than 25 mm less than the diameter shown in the Contract documents.

e. Excavation of the bearing area of bells shall have an area that is no less than the planned

bearing area.

f. All other plan dimensions shown for the bells may vary, when approved by the Engineer, to

accommodate equipment used.

A pile’s top elevation shall be within 50 mm of its planned elevation.

h. A pile excavation

’s bottom shall be normal to the axis of the pile within 60 mm per meter of

pile diameter.

The  Owner  shall  not  accept  drilled  pile  excavations  that  cannot  be  completed  within  the  required
tolerances.  In  such  cases,  the  Contractor  shall  submit  correction  methods  to  the  Engineer  for
approval, which must  be  obtained before the Contractor continues with the construction of drilled
piles.

The Contractor shall furnish materials and work that are necessary to effect correction for out-of-
tolerance drilled pile excavations at no cost to the Owner.

17.10

Pile Construction

Construction of drilled foundation piles shall meet all requirements outlined in this section.

17.10.1

Protection of Existing Structures

The Contractor shall take all reasonable precautions to prevent damage to existing structures and
utilities. Such measures shall include, but are not limited to, the following activities:

a. Construction methods and procedures that prevent excessive caving of the pile excavation
b. Monitoring and controlling vibrations caused by the driving of casing or sheeting, drilling of

the pile, dewatering or leakage of bentonite, or blasting (when such is permitted by the
Engineer)

17.10.2

Submittals for Drilled Pile Construction

Submittals for drilled pile construction shall meet all requirements outlined in Table 17-2.

Table 17-2: Requirements for drilled pile construction submittals

Requirement

Details

Pile Design
Confirmation

Tentative pile depths shown on the Contract plans shall be confirmed or modified
based on the Contract

or’s soil investigation and geotechnical report submitted

to the Engineer for review and approval.

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Requirement

Details

Shop Drawings The Contractor shall submit shop drawings to the Engineer for approval in

accordance the Contract standard specifications.

Method
Statement

The Contractor shall submit a method statement to the Engineer for approval.
This statement shall propose equipment and procedures for constructing piles
and include details of Non-working pile load tests. No work shall commence until
the Engineer approves the method statement and Non-working pile load testing
is complete and approved.

Materials
Submittals

The Contractor shall submit all proposed materials to the Engineer in
accordance with the relevant sections of the Contract standard specifications.
The Contract

or’s submittals shall include full details of the proposed mix design

for concreting the piles, casing, rebar, spacers, and concrete. No work shall
commence until the Engineer approves the proposed materials.

Quality Control The Contractor shall submit a detailed quality control plan for all activities related

to  drilled  piles.  Such  plan  shall  define  selected  tests  to  be  performed,  test
methods to be used, and property requirements that must be met to ensure that
the material and operation functions as intended. A quality plan must take into
consideration  the  anticipated  subsurface  conditions  and  pile  construction
methods,  in  accordance  with  the  slurry  manufacturer's  recommendations  and
these specifications.

Reports

The Contractor shall inform the Engineer each day of the intended piling program
for the following day and shall give adequate notice of intention to work outside
normal hours or over weekends.

17.10.3

Drilled Pile Construction Sequence

All excavations of the foundation in which drilled piles are to be constructed shall be complete before
the Contractor begins pile construction.

Unless  the  Contract  documents  indicate  that  drilled  piles  are  to  be  installed  in  conjunction  with
embankment  placement,  the  Contractor  shall  construct  them  after  placing  the  fill.  Otherwise,
allowance  for  negative  drag  shall  be  considered.  The  Contractor  shall  investigate

a pile’s group

action to determine the proximity of adjacent boring.

17.10.4

Drilled Pile Construction Methods

Excavations required for piles and bell footing, through whatever materials are encountered, shall
comply with the dimensions and elevations specified in the Contract documents or as directed by
the Engineer. Methods and equipment shall be suitable for the intended purpose and the materials
encountered. Generally, the Contractor may apply either the dry method, the wet method, the
temporary casing method, or the permanent casing method, as necessary to produce sound, durable
concrete foundation piles that have no defects.

The Contractor shall use the permanent casing method only when required by the Contract
documents or with the Engineer

’s direct authorization. When the Contract documents require a

particular method of construction, the Contractor shall use that method. If the Contract documents
do not specify a particular method, the Contractor shall select and use the most effective method to
properly accomplish the work, as determined by site conditions. Such methods are subject to
approval by the Engineer.

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17.10.4.1 Dry Method

When a site is on relatively dry land with a very deep groundwater table and site conditions are
suitable to permit pile construction, the Contractor shall use the dry construction method.

With the dry method, a pile’s sides and bottom remain stable without any caving, sloughing, or
swelling and may be visually inspected before the placement of concrete.

Steps for the dry method include drilling the pile, removing accumulated water and loose material
from the excavation, placing the reinforcing cage, and placing the pile concrete in a relatively dry
excavation.

17.10.4.2 Wet Method

When a site is in an area where a dry excavation cannot be maintained for the placement of the pile
concrete, the Contractor shall use the wet construction method. This method consists of using water
or mineral slurry to maintain stability of a hole's perimeter while advancing the excavation to its final
depth, placing a reinforcing cage, and concreting the pile.

Using the wet method involves the following work:

a. Desanding and cleaning the slurry
b. Cleaning the excavation using a bailing bucket, air lift, submersible pump, or other approved

device

c. Place pile concrete with a tremie or concrete pump, beginning at a pile

’s bottom

d. Providing, as needed, temporary surface casings to aid pile alignment and positioning
e. Providing temporary surface casings to prevent sloughing of the top of the pile excavation,

unless it can be satisfactorily demonstrated that the surface casing is not required

17.10.4.3 Temporary Casing Construction Method

The Contractor shall use the temporary casing construction method when neither the dry or wet
construction method is appropriate.

As an alternative to using the wet excavation method, the Contractor may use vibratory or driving
procedures to install temporary casing before excavation to the lower limits of the caving material.

Before and during the withdrawal of casing, the level of fresh concrete in the casing shall be such
that all the fluid trapped behind the casing is displaced upward without contaminating the pile
concrete.

To remove casing, the Contractor shall apply a rotary movement, downward pressure, and tapping
with a vibratory hammer to ease the extraction. Casing extraction shall be at a slow and uniform rate
with the pull aligned with the pile axis.

17.10.4.4 Permanent Casing Construction Method

The Contractor shall use the permanent casing construction method when required by the Contract
documents. This method involves driving or drilling a casing to a prescribed depth before excavation
begins. If this method cannot attain full penetration, the Engineer may require either excavation of
material within the embedded portion of the casing or excavation of a pilot hole ahead of the casing
until the casing reaches the desired penetration. Some cases may require over reaming to the
outside diameter of the casing to advance the casing.

A casing shall be continuous between the elevations shown in the Contract documents. The
Contractor shall not substitute temporary casing for permanent casing or add temporary casing to
permanent casing, except when specified in the Contract documents or so authorized, in writing, by
the Engineer.

After installing a casing and completing pile excavation, the Contractor shall place the reinforcing
steel and pile concrete within the portion of the casing that remains in place.

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17.10.4.5 Alternate Construction Methods

The Contractor may propose alternate methods to prevent caving and control ground water. Such
proposals, accompanied by supporting technical data, shall be submitted to the Engineer for
approval before the commencement of any related work.

17.10.5

Drilling

If the Engineer determines that foundation material encountered during pile drilling is unsuitable or
differs from design expectations, the Contractor may, during construction

, adjust a pile’s bottom

elevation from that shown in the Contract documents.

The Contractor shall take soil samples or rock cores in accordance with the Contract documents or
directions from the Engineer to determine the characteristics of materials directly below a pile
excavation. After inspecting the samples or cores, the Engineer shall determine the final depth of a
pile

’s excavation.

Disposal of excavated materials that are removed from a pile excavation and any used drilling fluids
shall comply with the Contract documents or directions from the Engineer.

When the Contract documents show bell footings, the Contractor shall excavate them, using
mechanical methods, to form a bearing area of the size and shape shown.

The Contractor shall give special consideration to the following requirements:

a. Before boring, the Contractor shall check the casing position for each pile during and

immediately after placing the casing; they shall get verification for such positions from the
Engineer.

b. The Contractor shall bore piles sufficiently far from other piles that have recently been cast

or that contain workable or unset concrete to avoid the induction of concrete flow from such
piles or damage to any such piles. A minimum spacing of 3.0m or three times the pile
diameter shall be provided.

c. Any proposals from the Contractor for ground treatment of any nature or for temporary

lowering of the water table (by well pointing or any other method) shall be subject to approval
by the Engineer. The Contractor shall, however, retain full responsibility for any effects to
existing roads, buildings, and structures in the vicinity of the Project works that result from
such ground treatment or control of water table levels.

d. Any proposals from the Contractor for underpinning, needling, and shoring structures in the

vicinity of the works shall reflect careful design. Such proposed designs shall be subject to
approval by the Engineer.

e. Where boring takes place through unstable water bearing strata, the process of excavation

and the depth of casing employed shall be such that soil from outside the area of the pile is
not drawn into the pile section and cavities are not created outside the casing as it is
advanced.

f. Where the use of drilling fluid is specified or approved for maintaining the stability of a bore,

the Contractor shall maintain the level of drilling fluid in the pile excavation within the cased
or stable bore so that it is not less than 1.0 meter above the level of external standing
groundwater at all times.

g. If a pile excavation loses drilling fluid rapidly, the Contractor shall backfill the bore without

delay and obtains instructions from the Engineer before resuming boring activity at that
location.

h. The Contractor shall take all reasonable steps to prevent the spillage of drilling fluid on the

site in areas outside the immediate vicinity of boring. Discarded drilling fluid shall be removed
from a site without undue delay. Any disposal of the drilling fluid shall comply with the
regulations of the local authorities.

i. For a pile constructed in a stable cohesive soil without the use of casing or other form of

support, the Contractor shall bore piles and place concrete without so long a delay that
significant impairment of the soil strength can occur.

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j. Each pile bore that does not contain standing water or drilling fluid shall be inspected directly

or indirectly before concrete placement. The Contractor shall provide equipment to enable
his representative and the Engineer such inspection. The Contractor shall verify the capacity
of the excavated base for each end-bearing pile.

k. After completing boring, when inspection of a pile bore indicates that such action is

necessary,  the  Contractor  shall  remove  loose,  disturbed,  or  softened  soil  from  the  bore.
Where  pile  bores  contain  water  or  drilling  fluid,  thorough  cleaning  shall  precede  concrete
placement.  To  remove  large  debris  or  accumulated  sediment,  the  Contractor  shall  use
appropriate approved methods that clean bores while minimizing ground disturbance below
pile bases. Water or drilling fluid shall remain at controlled levels throughout and following
cleaning to preserve bore stability.

17.11

Support for Pile Bores

The Contractor shall bear full responsibility for selecting and executing methods to stabilize and
maintain pile excavations. Walls and bottoms of pile excavations shall have sufficient protection to
prevent sidewall caving and bottom heaving. Such protection shall ensure that soil adjacent to a
pile’s bore shaft is not disturbed.

17.11.1

Support Fluid

Pile drilling processes shall use mineral slurry with both a mineral grain size that will remain in
suspension and sufficient viscosity and gel characteristics to transport excavated material to a
suitable screening system. Such fluid shall have a percentage and specific gravity that are sufficient
to maintain an excavation

’s stability and to allow proper concrete placement.

During drilling, slurry levels shall remain sufficiently high to prevent a hole from caving in.

Mineral slurry shall be premixed thoroughly with clean fresh water, and adequate time shall be
allotted for hydration prior to introduction into the pile excavation.

The Contractor shall provide adequate slurry tanks when such are a specified requirement in the
Contract documents. The Owner does not permit excavated slurry pits. The Contractor shall provide
adequate desanding equipment when such is specified in the Contract documents. The Contractor
shall take necessary steps, such as agitation, circulation, and property adjustment, to prevent slurry
from hardening in a pile excavation.

Using suitable apparatuses, the Contractor shall conduct control tests on the mineral slurry to
determine its unit weight (density), viscosity, and acidity (pH value). Table 17-3 and

Table 17-4 show acceptable values for those physical properties.

17.11.2

Use of Bentonite

All use of bentonite shall conform to the following requirements:

a. Bentonite, as supplied to a site and before mixing, shall comply with Specification DFCP-4 of

the Oil Companies Materials Association.

b. The Contractor shall obtain a certificate from the bentonite manufacture that shows the

properties of each consignment delivered to the Project site. The Contractor shall make this
certificate available to the Engineer on request.

c. Certified properties shall include the apparent viscosity range (in centipoises) and the gel

strength range (in newtons per square metre) for solids in water.

d. Bentonite shall be mixed thoroughly with clean fresh water to make a suspension that will

maintain

a pile bore’s stability for the period necessary to place concrete and complete

construction. Temperatures of water used in mixing a bentonite suspension and of the
suspension itself when supplied to the borehole shall exceed 5° C.

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e. Wherever saline or chemically contaminated groundwater occurs, the Contractor shall take

special precautions to modify a bentonite suspension or to prehydrate the bentonite in fresh
water to render it suitable in all respects for pile construction.

f. The Contractor shall propose drilling fluid testing frequencies, sampling methods, and

sampling procedures to the Engineer for approval before commencing work. With the
Engineer

’s approval, the Contractor may subsequently vary testing frequencies, depending

on fluid consistency.

g. The Contractor shall conduct control tests on bentonite suspensions, using suitable

apparatus. The Contractor shall measure the density of a freshly mixed bentonite suspension
every day to verify the quality of the suspension being formed. A measuring device for such
test shall be calibrated to read to within 5g/L. Tests to determine density, viscosity, shear
strength, and acidity (pH value) shall be applied to bentonite supplied to a pile bore. For sites
with average soil conditions for the Project, results of bentonite suspension tests shall
generally fall within the ranges shown in Table 17-3.

h. Testing shall continue until a consistent working pattern has been established, taking into

account  the  mixing  process,  any  blending  of  freshly  mixed  bentonite  suspension,  and
previously used bentonite suspension. When test results show that bentonite for the Project
has consistent behaviour, the Contractor may discontinue tests for shear strength and acidity,
but shall continue tests to determine density and viscosity in accordance with direction from
the  Engineer.  In  the  event  of  a  change  in  the  established  working  pattern,  the  Contractor
shall reintroduce tests for shear strength and acidity as necessary.

Table 17-3: Bentonite slurry properties

Slurry
property

Unit

Range of results at 20

Test method

Fresh

Before
concreting

Density

g/cm

<1.10

<1.15

Mud density balance

Viscosity

Sec

32 to 50 32 to 50

Marsh funnel and cup

8.0 ~ 11 -

pH indicator paper strips or electrical pH
meter

Sand content

4.0 %

Testing methods pertaining to Table 17-3 shall conform to American Petroleum Institute (API)
standards, as outlined in their standard procedure for testing drilling fluids (API

–RP13B). The

following equivalent test methods as per ASTM Standards can also be followed:

•

ASTM D4380-12:

Standard Test Method for Density of Bentonitic Slurries

•

ASTM D6910/D6910M-09:

Standard Test Method for Marsh Funnel Viscosity of Clay

Construction Slurries.

•

ASTM D4381/D4381M-12:

Standard Test Method for Sand Content by Volume of

Bentonitic Slurries.

17.11.3

Polymer Slurry

Polymer slurries shall be used in conformance with a manufacturer's recommendations and shall
conform to the quality control plan specified in Section 17.10.2. Only synthetic slurry systems that
have been approved by the Engineer may be used. The polymer slurry shall conform to the
requirements shown in Table 17-4.

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Table 17-4: Polymer slurry properties

Slurry property Unit

Requirements

Test method

Density

g/cm

1.03 Max

Mud density balance

Viscosity

Sec

32 to 135

Marsh funnel and cup

8.0 ~ 11.5

pH indicator paper strips or
electrical pH meter

Sand content

1.0% Max

When doing so is approved by the Engineer, the Contractor may use polymer slurry in salt water and
increase allowable densities to up to 3.0% over the value in

Table 17-4.

A polymer slurry

’s sand content before final cleaning and immediately before concrete placement

shall be less than or equal to 1.0 percent, in accordance with the section 5 of the American Petroleum
Institute

’s standard procedure for testing drilling fluids (API 13B-1). Slurry temperature shall be at

least 4.4° C when tested.

17.11.4

Casings

Casings for drilled foundation piles shall comply with the requirements outlined in this section.

17.11.4.1 General Casing Requirements for Drilled Piles

Casings shall be metal, smooth, clean, watertight, and of ample strength to withstand handling,
driving, extraction stresses, and the pressure of both concrete and surrounding earth materials. A
casing’s inside diameter shall not be less than the pile’s specified size.

If the Project plans specify a minimum thickness for casing, this thickness only satisfies structural
design requirements. The Contractor shall ensure that casing thicknesses satisfy the requirements
of construction installation, even when such thicknesses exceed the minimum.

17.11.4.2 Permanent structural Casing

A permanent structural casing is a part of the pile structure that provides stiffness or load carrying
capacity and shall remain in place after construction is complete.

17.11.4.3 Permanent Non-structural Casing

A permanent non-structural casing assists in the construction of the drilled pile and, like a permanent
structural casing, shall remain in place after construction is complete.

17.11.4.4 Temporary Casing

A temporary casing facilitates pile construction only, is not part of the pile structure, and shall be
removed completely after pile construction is complete, unless the Contract plans indicate otherwise.

All temporary casings shall be smooth-walled structural steel, unless the Contract plans indicate that
corrugated metal pipe is an acceptable alternative.

The casing shall be easy to remove without deforming or damaging the completed pile and without
disturbing surrounding soil.

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The Contractor shall remove temporary casings while concrete remains workable. Generally, the
Contractor shall begin to remove a temporary casing when concrete placement in a pile is at or
above ground level.

To remove casing, the Contractor shall apply a rotary movement, downward pressure, and tapping
with a vibratory hammer to ease the extraction. Casing extraction shall be at a slow, uniform rate
with the pull aligned with the pile axis. The Contractor shall not excessively rotate a casing to limit
deformation of the reinforcing steel cage.

Maintenance of a sufficient head of concrete above the bottom of a casing shall overcome the
hydrostatic pressure of water or drilling fluid outside the casing.

17.12

Placement of Pile Concrete

The Contractor shall place concrete as soon as possible after completion of drilled pile excavation
and after the Engineer inspects and approves the excavation.

Before placing concrete, the Contractor shall take measures to ensure that silt and other materials
do not accumulate at the base of a boring. The Contractor shall clean a pile

’s bottom (bearing

stratum) immediately before placing concrete.

17.12.1

Concrete for Drilled Piles

When the Contract documents specify a designed concrete mix, the Contractor shall be responsible
for selecting the mix proportions to achieve the required strength and workability, but the Engineer
will be responsible for specifying the minimum cement content and any other properties required to
ensure durability.

Concrete for drilled piles shall have sufficient workability to enable it to be placed and compacted by
the methods used in forming the piles.

For piles that are exposed to potentially aggressive ground or groundwater, the Contractor shall take
approved measures to ensure durability.

A mix’s cement content shall not be less than 360 kg per cubic metre. Where concrete will reside
under water or drilling mud, such mix shall not contain less than 380 kg of cement per cubic metre.
Where a pile will be exposed to sea water, a mix shall contain at least 400 kg of cement per cubic
metre. No mix shall have a water-to-cement (W/C) ratio greater than 0.4 and as described in Table
4-16 of Chapter 4, Concrete Works, of the

Standard Specifications

All concrete aggregates, cement, and water shall be sampled and tested as frequently as the
Engineer deems necessary. The Contractor shall supply all test samples at their own expense.

The Contractor shall prepare concrete trial mixes to show that the proposed mix proportions and
manufacture will produce concrete of the required strength and quality and shall have adequate
workability for compaction by the method to be used in placement.

The Contractor shall keep a detailed record of the results of all tests on concrete and concrete
materials. Each test shall be clearly identified to associate it with the piles to which it relates.

17.12.2

Placing Concrete under Water or Support Fluid

To place concrete that will reside under water or drilling fluid, the Contractor shall use the tremie
method and shall ensure that concrete is not discharged freely into the water or drilling fluid. Where
appropriate, the Engineer may approve pumping concrete.

A sample of the drilling fluid shall be taken from the base of the boring by using an approved sampling
device. If the specific gravity of the suspension exceeds 1.2 g/cm

, the Contractor shall not proceed

with concrete placement. In this event, the Contractor shall use a method approved by the Engineer
to modify or replace the drilling fluid to meet the specification.

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Concrete shall be placed in such manner that segregation does not occur.

Throughout  concrete  placement,  the  tremie’s  hopper  and  pipe  shall  be  clean  and  watertight.  A
tremie’s pipe shall extend to the base of the bore and  include a sliding plug or barrier to prevent
direct contact between the first charge of concrete in the tremie and the water or drilling fluid.

At all times until placement of concrete is complete, a tremie pipe shall penetrate the concrete that
was previously placed and shall be withdrawn at a rate such that ensures a minimum concrete head
of 2.0 m over the end of the tremie.

A tremie pipe’s internal diameter shall not be less than 150 mm

and its maximum size aggregate shall be 20 mm. External projections on a tremie pipe shall be
minimized to enable the tremie to pass within the reinforcing cages without causing damage. A
tremie pipe’s internal face shall not have any projections.

Concrete placement shall be one continuous operation. If the Contractor suspects that any
interruption to concrete placement has caused a cold joint, they shall chip the concrete, clean the
pile with compressed air to a level 50 mm below the joint

’s surface, and apply a suitable bonding

agent of a type that the Engineer has approved.

Sufficient concrete should overflow the top of a pile to ensure that the pile

’s shaft is clear of any

contaminating soil or slurry.

If a concrete placement operation is interrupted, the Engineer may require the Contractor to drill
cores and conduct other tests to prove that the pile contains no voids or horizontal joints. If such
testing reveals voids or joints, the Contractor shall repair them or replace the pile at no additional
cost.

The Contractor shall complete a concrete yield plot for each pile poured by tremie methods and
submit such yield plots to the Engineer no later than 24 hours after pouring concrete.

The Contractor shall not perform pile excavation operations within three diameters of a newly poured
pile any sooner than 24 hours after concrete placement.

17.13

Steel Reinforcement

The Contractor

’s shop drawings shall show all bracing and any extra reinforcing steel that is required

to fabricate a reinforcing cage. The Contractor shall be responsible for engineering the temporary
support  and  bracing  of  reinforcing  cages  to  ensure  that  they  maintain  their  planned  configuration
during  assembly,  transportation,  and  installation.  Steel  reinforcement  shall  meet  the  following
minimum  requirements  and  as  described  in  Chapter  5,  Reinforcing  Steel,    of  the

Standard

Specifications

a. At least four vertical bars of each cage, equally spaced around

a cage’s circumference, shall

be tied to all reinforcement intersections with double wire ties.

b. At least 25 percent of remaining reinforcement intersections in each cage shall be tied with

single wire ties. Tied intersections shall be staggered from adjacent ties.

c. Bracing shall prevent the collapse of each cage during its assembly, transportation, and

installation. At no additional cost, the Contractor shall provide any additional reinforcement
that is needed to allow a cage to be safely lifted and lowered.

d. Hoops, links, or helical reinforcement shall fit closely around the main longitudinal bars and

be bound to them by approved wire, the ends of which shall be turned into

a pile’s interior.

Successful compliance with these minimum baseline requirements for reinforcement cages shall in
no way relieve the Contractor of full responsibility for engineering the temporary supports and bracing
of the cages during construction. Such reinforcement shall be carefully positioned and securely
fastened to provide minimum clearances (as described in this section) and to ensure that no
displacement of the reinforcing steel cage occurs during concrete placement.

Each steel reinforcing cage shall be securely held in position throughout concrete placement to
provide the specified projection of reinforcement above the final cut-off level.

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Reinforcing steel in a pile shall be tied and supported so that the location of the reinforcing steel will
remain within allowable tolerance. The Contractor shall tie the bars to lateral tie bars at all
intersections. Concrete spacers or other approved noncorrosive spacing devices along a pil

e’s

bottom, along a pil

e’s top, and at sufficient intervals (not more than 2.0 meters vertically) shall ensure

concentric spacing for the entire cage length. Each level requires at least four spacers. Such spacers
shall be of adequate dimension to ensure an annular space between the outside of a reinforcing
cage and the side of the excavation along the entire length of a pile, as shown in the Contract plans.

The cover to all reinforcement in cast in place piles shall be not less than 100 mm unless otherwise
approved by the Engineer.

Acceptable feet made of plastic or concrete (bottom supports) shall ensure that the bottom of each
cage remains at the proper distance above the base of an excavation, unless a cage is suspended
from a fixed base when the Contractor pours concrete.

To allow concrete placement after lifting a cage, the Contractor shall remove bracing steel that
constricts the interior of a reinforcing cage.

Longitudinal steel bars shall have as few laps as possible. Joints in reinforcement shall be such that
the full strength of each bar is effective across the joint and shall be made so that there is no
detrimental displacement of the reinforcement during the construction of a pile.

17.14

Withdrawal of Temporary Casing

The Contractor shall extract temporary casings while the concrete within them remains sufficiently
workable to ensure that the concrete is not lifted. During extraction, the motion of a temporary casing
shall remain in an axial direction relative to its associated pile.

When extracting a casing, the Contractor shall maintain a sufficient quantity of concrete within it to
resist pressure from external water, drilling fluid, or soil and to ensure that the associated pile is
neither reduced in section nor contaminated.

When extracting a temporary casing, the Contractor shall top off the concrete level as necessary to
ensure that the base of the casing is always below the concrete surface until the casting of the
associated pile is complete.

When withdrawing a temporary casing could displace water or fluid as concrete flows into its final
position against the walls of a pile bore, causing excess heads of water or drilling fluid, the Contractor
shall take adequate precautions. Where two or more discontinuous lengths of casing (double casing)
are used in the construction, the Contractor shall obtain approval from the Engineer for their
proposed method of working.

During extraction of temporary casings, where circumstances are such that newly placed unset
concrete is brought into contact with external groundwater, the Contractor shall take precautions to
ensure that the internal concrete pressure at all levels within a pile exceeds the external groundwater
pressure.

17.15

Finishing Pile Heads

For piles cast in dry bores using temporary casing and without the use of a permanent lining, pile
heads shall be cast to a level above the specified cut-off so that, after trimming, a sound concrete
connection with the pile can be made.

A pile’s casing level shall be within the tolerance above the

cut-off level shown in Table 17-5, but shall not be above the commencing surface level. No pile shall
be cast with its head below standing water level unless the Contractor takes approved measures to
prevent the inflow of water from causing segregation of the concrete when a temporary casing is
extracted.

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Table 17-5: Casting tolerance for piles cast in dry bores using temporary casing and without

a permanent lining

Cut-off distance below

commencing surface H (m)

Casting tolerance above Cut-off Level (m)

0.15 - 10.00 meters

0.3+H/12+C/8 meters

H = Height of the commencing surface

C = length of temporary casing below the

commencing surface

For piles cast in dry bores within permanent lining tubes or permanent casings, or where pile cut-off
levels are in stable ground below the base of any casing used, pile heads shall be cast to a level
above the specified cut-off so that, after trimming, a sound concrete connection with the pile can be
made. Casting levels shall be within the tolerance above

a pile’s cut-off level as shown in Table 17-6,

but shall not be above the commencing surface level.

Table 17-6: Casting tolerance for piles cast in dry bores within permanent lining tubes,

permanent casings, or where cut-off levels are in stable ground below the base of any

casing used

Cut-off distance below

commencing surface H (m)

Casting tolerance above Cut-off Level

0.15 - 10.00 meters

0.3 + H / 10 meters

H = Height of the commencing surface

For piles cast under water or drilling fluid, the pile heads shall be cast to a level above the specified
cut  off  so  that,  after  trimming  to  remove  all  debris  and  contaminated  concrete,  a  sound  concrete
connection with the pile can be made. The casing level shall be within the tolerance above the cut
off level shown in Table 17-7, but shall not be above the commencing surface level. Cut off levels
may  be  specified  below  the  standing  groundwater  level,  and  where  this  condition  applies  the
borehole fluid level shall not be reduced below the standing groundwater level until the concrete has
set.

Table 17-7: Casting tolerance for piles cast under water or drilling fluid*

Cut off distance below

commencing surface H (m)

Casting tolerance above Cut-off Level (m)

0.15 - 10.00

0.3+H /12+C/8

Where C = length of temporary casing below the

commencing surface

* In cases where a pile is cast so that the cut-off is within a permanent lining tube, the appropriate
tolerance is given by deletion of the casing term (C/8).

Where

a pile’s cut-off level is deeper than 10 meters below the commencing surface, the Contractor

must alter the tolerances given in Table 17-5, Table 17-6, Table 17-7, taking special conditions into
account and based on discussion with the Engineer, before commencing piling.

When cutting off and trimming a pile to its specified cut-off level, the Contractor shall avoid shattering
or otherwise damaging the rest of the pile. The Contractor shall cut away any cracked or defective

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concrete and repair the pile repaired in a manner approved by the Engineer to provide a full and
sound section at the cut-off level.

17.16

Pile Testing

The Contractor shall conduct a total number of pile tests on working piles as specified in the Contract
plans or as required by the Engineer. An independent testing organization that has been approved
by the Engineer shall monitor and analyse all load tests.

Terms and their definitions given below apply to pile testing.

Compression Pile:

A pile that, by design, resists axial force that would cause it to penetrate further

into the ground.

Non-working Pile:

A pile installed before the commencement of the main piling works as a test pile

specifically installed to establish suitability and to confirm

a pile’s dimensions and capacity.

Working Pile:

Any pile installed as part of the permanent work.

Test Pile:

Any pile to which a test is or will be applied.

Kentledge:

A dead weight used in a static loading test.

Reaction System:

An arrangement of kentledge, piles anchors, or rafts that provides a resistance

against which a pile is tested.

Maintained Load Test:

A loading test in which each increment of load is held constant either for a

defined period of time or until the rate of movement (settlement or uplift) falls to a specified value.
Such testing accounts for thermal allowances.

Failure Load Test:

A load test applied to a Non-working pile. Normally, a load for this test should

be 200% of

a pile’s estimated working load unless specified otherwise. However, in all cases the test

load shall not exceed 300% of the pile’s working load. This test evaluates soil parameters that
designers use to determine the required lengths of working piles.

Working Load Test:

A load test that is applied to a selected working pile to confirm that it is suitable

for the load at the specified settlement. Normally, a load for this test should not exceed 150% of a
pile’s service design load. This test serves as a quality control check on working piles.

Allowable Load:

A maximum load that may be safely applied to a pile. This load takes into account

a pile’s section ultimate capacity, negative skin friction, pile spacing, overall bearing capacity of the
ground below, and allowable settlement.

Working load:

A load that a pile is designed to carry without exceeding the specified allowable

settlement requirement.

Integrity Testing:

Low-frequency or high-frequency dynamic testing that verifies that a pile

’s body

is free of defects

17.16.1

Measuring Devices

The Contractor shall submit their proposed method of measuring the movement of pile heads and
load to the Engineer for approval.

17.16.1.1 Measurement of Load

To measure a pile’s load, the Contractor shall use a load measuring device and a recently-calibrated
pressure gauge included in

a pile’s hydraulic system. The Contractor shall record readings from both

the load measuring and the pressure gauge. In interpreting the test data, the values given by the
load measuring device shall normally be used. Readings from the pressure gauge provide a check
for gross errors.

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A load measuring device may consist of a proving ring, load measuring column, pressure cell, and
other appropriate systems. Any devices that are sensitive to eccentric loadings shall include a
spherical sheathing. Load measuring devices and jacks shall have short axial lengths to achieve the
best possible stability. The Contractor shall be careful to avoid any risk of buckling. The Contractor
shall also ensure that axial loading remains constant throughout load testing. Loads during testing
shall not fall below 1% of

a pile’s specified load.

To modify the load testing requirements outlined in this section in any way, the Contractor must
obtain the Engineer

’s authorization in advance.

Load measuring devices shall be calibrated before and after each series of tests, whenever
adjustments are made to the device or at intervals appropriate to the type of equipment. Pressure
gauges and hydraulic jacks shall be calibrated together.

The Contractor shall supply certificates of calibration, performed by an approved testing laboratory,
to the Engineer before conducting load testing. The calibration certificate shall be recent and in all
cases shall not be older than 6 months from the test date.

17.16.1.2 Measurement of Settlement

To  measure  settlement,  the  Contractor  shall  use  a  reference  beam  or  wire  that  is  supported
independently  of  the  pile  begins  tested,  reaction  piles,  or  piles  that  support  reaction  loads.
Settlements shall be measured to the nearest 0.1 mm for reference beams and to the nearest 0.5
mm for reference wires. The Contractor shall use a precise optical level to check movements of the
reference frame against an independent datum. Reference beam supports shall be at least 3 meters
from test piles, reaction piles, or piles that support reaction loads. Reference beams or wires shall
be  protected  from  the  effects  of  temperature  changes.  Construction  equipment  and  persons  not
involved  in  settlement  measurement  shall  remain  well  clear  to  avoid  disturbing  the  measuring
system. Pile drilling or similar operations shall not occur in the vicinity of the test unless the Engineer
is satisfied that such activity will not affect the measuring system.

To obtain precise measurements of deflections, the Contractor shall use at least four dial gauges
that are equally spaced around the head of a test pile to collect measurements. Such measurements
shall be accurate to within 0.01 mm to ensure that the information on pile bending and axial
movement is useful. Dial gauges that are firmly attached to the reference beams shall ensure that
plungers are parallel to a tested pile

’s axis. Plunger points shall bear onto reference plates by means

of machined plates or glass slides that are attached to a tested pile

’s head. Reference plates shall

be equidistant from the centre of a tested pile

’s axis to eliminate axial components that sideways

movements could otherwise produce. The Contractor shall also monitor and document elastic
deformation.

With authorization from the Engineer, the Contractor may implement other suitable and adequate
methods to measure the movement of pile heads.

Before conducting load tests, the Contractor shall give the Engineer certificates that verify that an
approved testing laboratory has calibrated all dial gauges that will be used.

17.16.2

Reaction System

All reaction systems for drilled foundation piles shall comply with the requirements outlined in this
section.

17.16.2.1 Compression Tests

To test compression loaded drilled piles, the Contractor shall use a kentledge reaction system,
tension piles, ground anchors, or otherwise specially-constructed anchorage. The Owner prefers the
use of a kentledge system for load tests on vertical piles; the Engineer shall permit the use of tension
reaction piles, ground anchors, or other tension reaction systems only when use of a kentledge
system proves impractical. The Contractor shall not use a kentledge system to test raking piles.

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A kentledge system, when used, shall be supported on cribwork that is disposed around a tested
pile

’s head so that its centre of gravity is on the pile’s axis. Bearing pressures under supporting cribs

shall ensure stability of a kentledge

system’s stack. A tested pile’s head shall not directly carry a

kentledge system unless the Engineer specifically directs such as arrangement.

A kentledge system may include concrete blocks, steel weight, and other components, but such
components must be of uniform size so that the Contractor can easily calculate the total weight of
the kentledge.

17.16.2.2 Working Piles in a Reaction System

Without authorization from the Owner, the Contractor shall not use working piles as reaction piles.
When using working piles as reaction piles, the Contractor shall measure their movement to the
nearest 0.5 mm. The Contractor shall revise the design of the working piles that intended to be used
as reaction piles to ensure its adequacy to the applied load.

17.16.2.3 Ground Anchors in a Reaction System

Ground anchors shall be pre-loaded to provide reaction greater than the specified capacity of the
test assembly. Such pre-loading shall prevent unrestrained lateral movement by maintaining
sufficient contact stress throughout pile tests between loading beams and loading beam supports.
The Contractor shall obtain approval from the Engineer to pre-load ground anchors.

Each ground anchor shall be loaded to 1.2 times its approved capacity. A ground anchor shall hold
this load held for five minutes while the Contractor measures and records tendon extension at one
minute intervals. If these measurements indicate that the ground anchor is satisfactory, the
Contractor may lock it at an accepted load that exceeds the

anchor’s pre-loading force to allow for

loss due to creep.

Anchor piles and ground anchors, when used, shall be at least 2.5 metres or three times the pile
diameter from the test pile, measured centre to centre, or at a greater distance if the Engineer so
directs. The Contractor must ensure that such anchors cannot be pulled out, with a safety factor of
at least 2.0. Soil and rock properties that the Contractor uses to determine this safety factor shall
have approval of the Engineer.

17.16.2.4 Spacing Between Piles and Reaction System Structures

When the Contractor uses a kentledge reaction system to load vertical piles in compression, the
edge of a test pile shall be at least 1.3 metres from the nearest part of the crib that supports the
kentledge

system’s stack that also contacts the ground.

Centre-to-centre spacing between vertical reaction piles, including working piles that function as
reaction piles, and any test pile shall be at least five times the diameter of a test pile, five times the
diameter of the reaction piles, or three metres, whichever is greater. The Engineer may modify the
pile spacing requirement to suit site conditions at no extra costs.

Where ground anchors provide a test reaction for loading in compression, no part of the section of
the anchor that transfers load to the ground shall be closer to a test pile than three times the test
pile’s diameter. The Engineer may modify the pile spacing requirement to suit site conditions at no
extra costs.

17.16.2.5 Requirements for Piles and Anchors in a Reaction System

A reaction system shall have piles and anchors of sufficient sizes, lengths, and quantities to safely
transmit the maximum test load to the ground without excessively moving or influencing test piles.

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17.16.2.6 Care for Piles

The method employed in the installation of any reaction piles, anchors shall be such as to prevent
damage to any test pile or working pile.

17.16.2.7 Loading Arrangement

The loading arrangement shall safely transfer the maximum load required for testing to a test pile.
The Contractor shall submit full details to the Engineer for approval before doing any testing activity
at the Project site.

17.16.2.8 Pile Caps and Structural Elements

The Contractor shall design and build all temporary pile caps and other structural elements that form
part of a reaction system. Before commencing work, however, the Contractor shall submit a proposal
for pile caps and structural elements to the Engineer for approval. The Contractor shall bear the cost
of building and demolishing such pile caps and structural elements.

17.16.3

Equipment for Applying Load

One or more hydraulic rams or jacks shall serve as the principle equipment to apply loads to piles.
Such rams or jacks shall be arranged in conjunction with the reaction system to deliver an axial load
to the associated test pile. A complete system shall be capable of transferring the maximum load
required for each test.

Jacks shall have a total capacity that exceeds the required maximum test load by 20% or more,
thereby avoiding a heavy pumping effort when nearing maximum load and minimizing the possibility
of any oil leakage through seals.

Loading equipment shall be capable of adjustment throughout a load test to ensure smooth loads
increases and a consistent load as required at different stages of load testing.

17.16.4

Special Requirements for Test Piles

Test piles shall comply with the special requirements outlined in this section.

17.16.4.1 General Requirements for Test Piles

When preparing for, conducting, and dismantling a pile test, the Contractor shall provide and
maintain safe working conditions in compliance with all requirements of acts, orders, regulations and
other statutory mandates that apply to the specific work. In addition, the Contractor shall make such
other provisions as necessary to safeguard against hazards that are involved in testing or
preparation for testing. All reinforcement for piles that will be used as tensile piles during testing shall
be welded.

17.16.4.2 Personnel for Pile Testing

An experienced and competent supervisor who is conversant with the test equipment and test
procedures shall actively direct all pile tests. All personnel who operate test equipment shall have
been trained in the use of such equipment.

17.16.4.3 Kentledge for Pile Testing

When using kentledge, the Contractor shall construct the foundations for the kentledge and any
cribwork, beams, and other supporting structures to prevent differential settlement, bending, or
deflection that constitute hazards to safety or that impair the efficiency pile testing. Kentledge shall
be adequately bonded, tied, or otherwise held together to prevent it from the falling apart or becoming
unstable.

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The kentledge reaction system shall weigh at least 1.2 times more than the maximum test load.
When using the density and volume of

a kentledge system’s constituent materials to estimate weight,

the Contractor shall allow an adequate margin of error to ensure safety. The Contractor shall take
all reasonable steps to ensure that sufficient excess load capacity is at all times available for the
uninterrupted execution of any load test.

17.16.4.4 Tension Piles and Ground Anchors for Load Testing

When using tension piles or ground anchors, the Contractor shall ensure that the load is correctly
transmitted to all the tie rods and bolts. The Contractor shall not extend rods by welding unless doing
so does not weaken the steel. Bond stresses for rods in tension shall not exceed normal permissible
levels for the type of steel and grade of concrete used.

17.16.4.5 Pile Testing Equipment

In all cases, the Contractor shall ensure that, when a hydraulic jack and load measuring devices are
mounted on a test pile

’s head, the whole system will be stable under all loads to be applied up to the

maximum test load. To ensure safety, testers shall be able to read dial gauges from a position that
is clear of the kentledge stack or test frame.

Hydraulic jacks, pumps, hoses, pipes, couplings, and other apparatuses to be operated using
hydraulic pressure shall be able to withstand test pressures equal to of one and a half times the
maximum working pressure without leaking.

Gauges on pile testing equipment shall clearly display maximum test loads or test pressures. All
operators shall be made aware of these limits.

17.16.5

Maintained Compression Load Testing for Piles

Static load tests shall follow American Society for Testing and Materials (ASTM) procedures, as
specified in their

Standard Test Methods for Deep Foundations Under Static Axial Compressive Load

(ASTM D1143/D1143M-07e1). Loading procedures shall comply with the Quick Load Test Method,
unless detailed longer-term load-settlement data are needed, in which case load testing shall comply
with the standard procedure.

Testing equipment and measuring systems shall also conform to ASTM D1143/D1143M-07e1.

17.16.6

Working Piles

The Contractor shall conduct pile tests on working piles, as directed by the Engineer, any time before
a pile is built into a structure. Such testing helps to ensure that materials, workmanship and
performance comply with the quality standards and the requirements outline in these specifications.
Such tests help determine the displacement (and recovery) of a pile under a maximum test load that
is 1.5 times the working load indicated in the Contract documents.

The Owner prohibits the use of working piles as tension reaction piles for the purpose of conducting
these tests unless approved otherwise.

17.16.7

Pile Testing Procedure

The Contractor shall submit a detailed load testing proposal to the Engineer for approval, and must
have this approval in writing before conducting any load testing.

This proposal shall specify the number of working load tests to be carried out as per the Contract
Documents. The Engineer may reduce the number of tests after such testing routinely and
consistently indicates that workmanship and pile materials are of high quality and if the nature of soil
conditions encountered does not vary substantially. Conversely, the Engineer reserves the right to
increase the number and frequency of tests as needed to verify the quality of workmanship and pile.

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Unless the Engineer directs otherwise, the Contractor shall adhere to the test procedure outlined in
this section, with the percentage for loading and unloading operations given in terms of the working
load taken as 100%.

Table  17-8  provides  an  example  schedule  for  compression  testing;  this  example  schedule  is  for
guidance  only.  Actual  compression  testing  schedules  for  the  Project  are  subject  to  variation,  as
directed by the Engineer, to meet site conditions.

All loading and unloading operations shall take place during the day as possible. The Contractor
shall take at least three sets of readings during each loading or unloading stage, including one set
of readings at the beginning of a stage, a second set in the middle of a stage, and a third set at the
end of a stage. When applying a test load progressively and maintaining it for more than 30 minutes,
the Contractor shall take readings at least once every 30 minutes thereafter, unless the Engineer
specifies otherwise.

If large discrepancies occur between different measurement systems, testing shall pause until the
Contractor corrects the cause for such discrepancies. Testing shall resume from the beginning of
the test for the corrected instance.

Table 17-8: Loading cycles for test piles

Load

(percentage of working

load)

Time of holding

load

Remarks

25%

1 hour

50%

1 hour

75%

1 hour

100%

1 hour

75%

10 minutes

50%

10 minutes

25%

10 minutes

1 hour

100%

6 hours

125%

1 hour

150%

6 hours

125%

1 hour

100%

10 minutes

75%

10 minutes

50%

10 minutes

25%

10 minutes

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Load

(percentage of working

load)

Time of holding

load

Remarks

1 hour

Applicable to tests on Non-working piles only

100%

6 hours

150%

6 hours

175%

1 hour

200%

6 hours

175%

10 minutes

150%

10 minutes

125%

10 minutes

100%

10 minutes

75%

10 minutes

50%

10 minutes

25%

10 minutes

1 hour

17.16.8

Abandonment of Pile Test

The Contractor shall discontinue testing under any of the following conditions:

a.  A jack or gauge is faulty
b.  A kentledge reaction system is unstable
c.  A data setting is incorrect or improper
d.  Bench marks or scales are unstable
e.  Measuring instruments have been tampered with by anyone
f.  Measuring instruments have not been calibrated
g.  Pre-jacking of pre-loading occurred before commencement of testing
h.  Settlement exceeded the limits specified for the Project

After halting any test, the Contractor shall rectify the associated errors, consult with the Engineer,
then resume testing in accordance with the Engineer

’s instructions.

17.16.9

Pile Testing Record

The Contractor shall submit a written summary of testing to the Engineer no later than 24 hours after
completing a test (unless otherwise directed). This summary shall provide the following details for
each completed test within the 24-hour period:

•

The loading stage, the load, the period for which a load was held, and the maximum

settlement or uplift recorded

•

Load-to-settlement curve

Abu Dhabi, United Arab Emirates. STANDARD CONSTRUCTION SPECIFICATIONS (PART 2 - ROAD STRUCTURES, 2020) - page 1