Sample specifications should always be tailored to site specific conditions and design intent.
Verification testing of work should be focused on quality aspects most important to satisfying the
design. Hayward Baker Inc. makes no representation or warranty as to the applicability of this
specification to a particular design or use and shall not be liable for the use of this draft
specification, whether in whole or in part.
SAMPLE SPECIFICATIONS FOR
COMPACTION GROUTING PRE-TREATMENT
IN KARSTIC CONDITIONS
PART 1
GENERAL
The work covered in this specification consists of providing all labor, equipment and materials and performing all
operations in connection with site improvement to reduce the risk of structure settlement and future sinkhole activity by
pre-treatment of the foundation soils with compaction grouting.
1.01
INTRODUCTION
A.
Compaction grouting for sinkhole pre-treatment involves the injection of a low-slump, mortar-like grout,
under high pressure to fill voids, seal the bedrock surface and compact and displace the adjacent soils
near the throat of, and above, any potential sink within the treatment area.
B.
In situ soil:Typically porous or residual soils overlying a weathered rock stratum just above a solutionprone (karst) limestone rock.
C.
Applications:
Improvement of soil in karstic regions to reduce the risk of sinkhole activity and
improve bearing capacity.
1.02
The intent of the compaction grouting specified herein is to provide soil improvement within the limits indicated
on (..............................) drawings nos. ........................to achieve the required degree of improvement detailed in
section 3.02 of these specifications.
1.03
REFERENCES
A.
Reference documents as provided to the grouting contractor shall include:
1.
This specification.
2.
Project drawings:
a.
Engineer’s foundation plan, drawing no.......................
b.
Engineer’s existing underground utilities plan in the work area.
c.
Grout injection point layout, as detailed in the Submittals section 1.06 of these
specifications.
3.
Project geotechnical report.
4.
Contract documents.
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1.04
1.05
1.06
DEFINITIONS
A.
Compaction grout : A material blend of fine aggregate, fines and water to achieve a pumpable,
thixotropic, viscous grout of a low slump to enable pumping at high pressure and remain intact after
injection. Material components can include sand, silt, clay, cement, ground slag, flyash, water and other
inert materials. Strength of grout is designed to be [spec strength or % cement minimum here] and to
provide a permanent, non-erodible material.
B.
Karst: A type of geology in which the overburden soil overlays an eroding limestone formation.
C.
Field Quality Control Representative: The individual given specific inspection tasks identified in this
specification.
SCOPE OF WORK
A.
The work shall consist of performing, monitoring and testing of compaction grouting within the limits
indicated on (..............................) drawing no.................. to meet the acceptance criteria presented in
Section 3.02 of these specifications.
B.
In connection with the compaction grouting program, as shown on the drawings, the grouting contractor
shall provide all labor, materials and equipment to accomplish the following items of work:
1.
Install and remove grout pipes.
2.
Furnish and inject compaction grout.
3.
Monitor ground surface / structure movements during compaction grouting operations.
4.
Record compaction grouting process, including pressures, depths, injected volumes, and
movements for each stage and location.
5.
Follow compaction grouting sequence of operations.
SUBMITTALS
A.
The following shall be submitted to the Owner’s representative by the grouting contractor with the bid
documents:
1.
B.
A list of at least five previously completed projects of similar scope and purpose for approval
by the Owner’s representative. The list shall include a description of the project, relative
size, and contact person with phone number.
The following shall be submitted to the Owner’s representative by the grouting contractor _______
weeks prior to the start of the work:
1.
Resumes of the management, supervisory, and key personnel, for approval by the
Owner’s representative, as detailed in Section 1.07 of these specifications.
2.
A ground movement monitoring plan, as detailed in section 3.03 of these
specifications.
3.
A mix design for the project indicating sources and types of grout materials, with
volumetric proportions, and field test data from previous projects indicating
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compressive strength and slump of ....... to ........ inches (....... to .............. mm) or
less achieved. If the grouting contractor intends to deviate from the gradation
provided in Section 2.03 of this specification, it shall submit, with the bid, evidence
of satisfactory use of the proposed material from past projects with similar soil
conditions.
C.
1.07
Work procedures and control criteria (including volumes and pressure for each
stage).
5.
A general Work Procedures Plan outlining the spacing, location, depth and estimated
quantity of grout to achieve the specified criteria detailed in Section 3.02 of these
specifications.
The following shall be submitted to the Owner’s representative by the grouting contractor during the work:
1.
Accurate daily records of all grout pipe installation, compaction grouting quantities,
including stage data, volume, pressure and depth for each grout pipe location.
2.
Any change in the predetermined grouting program necessitated by a change in the
subsurface conditions.
3.
Verification of rock depth and quality during drilling, as evidenced by drilling resistance
recorded on drilling logs.
QUALITY ASSURANCE
A.
The compaction grouting program, including installation of grout pipes, shall be performed by a specialist
grouting contractor with at least ten continuous years of documented experience in compaction grouting.
B.
The grouting contractor shall provide experienced management, supervisory and key personnel as required to
implement the compaction grouting program, as follows:
C.
PART 2
2.01
4.
1.
The project manager shall have at least five years of continuous experience in compaction
grouting, with at least the last two years in the full-time employ of the grouting contractor.
2.
The superintendent shall have at least five years of experience in compaction grouting.
3.
As detailed in Section 1.06 of these specifications, the grouting contractor shall provide:
a.
Evidence of previous compaction grouting project experience of similar
scope and purpose.
b.
Evidence of management, supervisory and key personnel experience.
The Owner’s representative will ensure that procedures and documentation conform to these
specifications and submittal requirements.
EQUIPMENT AND MATERIALS
GROUTING EQUIPMENT
A.
The grouting contractor shall supply equipment capable of advancing the grout pipe through overburden, soils
and other natural obstructions to the specified depth or as required to meet the project objectives.
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B.
The grouting contractor shall supply all equipment required to operate a compaction grouting system capable of
supplying the specified grout at variable flow rates and pressures, measured at the pump, up to........psi (.........
kPa) and at rates of ...... to ...... cubic feet (..... to ........ cubic meters) per minute, as required to suit the
application.
C.
The mixer shall be a continuous auger type to ensure complete uniform mixing of the materials used and shall be
of sufficient capacity to continuously provide the pumping unit with mixed grout at its normal pumping range.
The mixer must be capable of volumetrically proportioning the grout materials. Ready mixed grout is also
acceptable with an approved mix design.
D.
The grouting contractor shall provide gauges or other instrumentation (measuring devices) to measure:
1.
2.
3.
4.
2.02
2.03
Grout pressure (gauge close to the top of the injection casing).
Flow rate of grout.
Volume of grout injected.
Heave, as measured by ground/structure movement monitoring system.
E.
The grouting contractor shall supply and install ground/structure movement monitoring equipment in
accordance with Section 3.03 of these specifications.
F.
An adequate communication system shall be maintained between the pumping location and the injection
location. As an alternative, the contractor may provide a remote control system to allow full control
(start, stop, flow rate, and reversing) of the pump, directly by the grouting technician from the injection
point.
GROUT PIPES AND INSTALLATION
A.
Grout pipes, casings, and connections shall be steel casing of adequate strength to maintain the hole and
to withstand the required installation, jacking and pumping stresses. The pipes shall be a minimum of
3.0 inches (75 mm) inside diameter in order to adequately handle the specified low slump material
without plugging [2.0 inch (30mm) inside diameter may be allowed under certain restricted access
situations]. All casing shall be flush joint threaded or a single piece tubing to provide a smooth inner wall
and unobstructed inside diameter. All fittings (elbows, bends, adapters, reducers, etc.) shall be long
sweep, gradual transition pieces specifically designed and manufactured for high pressure grout and
concrete pumping applications. Standard pipe elbows and reducers will not be allowed. It shall be the
contractor’s responsibility to install casing that does not detrimentally impact the grouting procedure.
B.
Casings shall be sized and installed such that grout material will not travel in the annulus area between
the pipe and adjacent ground and escape at the surface when pumped.
C.
All grout pipes shall be advanced through at least 5 ft of continuous, competent rock to provide
reasonable assurance that the grout hole has not been terminated in a boulder ‘floater’ or a rock pinnacle.
GROUT MATERIALS
A.
Portland Cement (ASTM C150)
B.
Fine aggregate shall be sand with a fines content (percent passing No. 200 sieve) of not less than 10
percent and not more than 30 percent. Natural fines may be supplemented with fly ash, bentonite, or
aggregate washings.
C.
Proportions of the mixture shall be as required to achieve a pumpable mix with a maximum ______inch
(_____mm) slump.
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D.
PART 3
3.01
EXECUTION
SITE EXAMINATION
A.
3.02
Upon discharge into the pump hopper or holding tank, the grout must be continuously agitated. Mixed
grout may not be held in the agitator for more than 1.5 hours unless a set retarder, approved by the
Owner’s representative, is used.
Prior to submitting a bid price for the compaction grouting, the grouting contractor shall conduct a site
inspection.
COMPACTION GROUTING
Note: Compaction grouting may be performed under either a performance-based or a method-based
specification. Select Section 3.02A (performance-based) OR 3.02B (method-based), as appropriate.
A.
B.
Compaction grouting shall be performed in accordance with the approved grout injection point layout
scheme to achieve the following acceptance criteria in the in situ soil between the injection points:
1.
Post-grouting average, corrected Standard Penetration values exceeding __________in
typical site soils test. Locations are to be agreed upon between the grouting contractor and
the Owner/Engineer. Averaging shall be with values above and below each value.
2.
Post-grouting, average corrected static Cone Penetrometer tip resistance, in silts with friction
ratio less than ___________ exceeding __________tsf (..........kPa). Locations are to be
agreed upon between the grouting contractor and the Owner/Engineer. Averaging shall
include above and below two feet, eliminating values in soils with permeability less than
1x10-3 cm/sec.
Compaction grouting shall be performed in accordance with the approved grout injection point layout
scheme. The grout shall be injected at a stage depth until one of the following occurs:
1.
Maximum grout pressure of ___ psi (____ kPa) is reached.
2.
Surface ground heave of _____ is observed.
3.
An injected grout volume equal to ......... percent of the soil volume being treated by
that injection stage is reached.
4.
A maximum cumulative heave of _________inches (_______mm) is observed.
5.
When the injection pipe tip is at or below the bedrock surface, injection pressures shall not
exceed 200 psi (1380 kPa), and grout injection will continue until a steady increase in
pressure is occurring, at which time that stage will be deemed complete and the pipe may be
extracted to the next stage.
Upon attaining one of the above refusal criteria, the grout pipe shall be lifted 2 feet (0.6m) and the
process repeated.
Note: 3.02B1 to 5 may be deleted by reference to the contractor’s work plan
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3.03
C.
Compaction grouting shall be sequenced so that grouting does not take place within _______ ft
(_____m) of locations grouted within the previous 12 hours.
D.
As compaction grouting is completed at each location, the grouting contractor shall completely fill the
grout hole to the ground surface.
FIELD QUALITY CONTROL
A.
All compaction grouting shall be performed under the inspection of the FQCR.
B.
Monitoring and logging of compaction grouting operations for both test areas and production work shall
be done by the FQCR.
C.
The FQCR will perform slump tests of grout and take measurements of grout mix quantities to verify the
grouting contractor’s grout mix, as follows:
1.
Slump tests will be performed:
a.
b.
c.
2.
3.04
once for every_____ cubic ft (___cubic meters) of grout injected, or
at any change in mix design, or
at least twice during each grout shift.
Grout mix proportions will be verified at least once daily.
D.
The FQCR will require the grouting contractor to cast minimum size 3 inch by 6 inch (75 mm by 150
mm) grout test cylinders or 2 inch by 2 inch (50 mm by 50 mm) cube molds for strength testing. One set
of four cylinders or molds will be cast during each slump test, or at least once per day.
E.
Layout of grout injection points shall be checked by the FQCR.
F.
As detailed in Section 1.06C, daily records shall be maintained by the grouting contractor and submitted
to the Owner’s representative.
G.
The grouting contractor shall monitor nearby structures as follows:
1.
A level control system will be installed by the contractor for each structure within
_____ ft (_____ m) of the grouting operations.
2.
Monitoring shall be carried out on a continuing basis whenever compaction
grouting is occurring within a horizontal distance equal to the depth of treatment.
3.
After completion of the compaction grouting program, the monitoring system and
grout pipes will be removed and all holes will be filled and patched.
TESTING AND INSPECTION
A.
The effectiveness of the proposed grouting layout scheme shall be verified as follows:
1.
The Owner may retain a soil testing firm to perform the in situ testing as directed by
the Owner’s engineer. Test sections will be performed before and during production
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work, as follows:
B.
3.05
Note:
Test section locations will be agreed upon by the (FQCR/grouting contractor)
within the treatment area. A test section shall consist of a single module comprised
of at least 3 grout injection points for isolated footings and 16 grout injection points
for area applications. Tests will be performed at the center of the module prior to
and after grouting.
b.
The method of installation of the test section shall comply with Section 3.02 of this
specification and shall be performed using the same grout line sizes, grout mix
drilling and grouting equipment and procedures as that to be used for production
work.
c.
Prior to commencement of production grouting,____ test sections shall be
performed. If the pre-production test sections indicate that the required ground
improvement has not been achieved, the grouting contractor shall revise the Work
Procedure Plan and re-test.
Monitoring and logging of compaction grouting operations in the test areas and for production work shall
be done by the grouting contractor.
RESTRICTIONS
A.
The Owner or General Contractor or Specialty Contractor shall be responsible for obtaining any State
and municipal permits (if required) and conforming to all State and local regulations.
B.
The owner will be responsible for the precise delineation of all above and below ground utilities and
obstructions.
The following shall also be listed within this section when applicable:
1.
2.
3.
PART 4
4.01
a.
Environmental restrictions.
Work boundaries.
Hours for construction.
PAYMENT
METHOD OF PAYMENT
A.
Layout of grout injection locations, installation of the grout casings required, and any required secondary
grouting within the limits indicated as requiring compaction grouting on __________________drawing
nos_______________ shall be a unit cost per linear foot of grout pipe, as measured from the ground
surface to the maximum depth penetrated by the grout pipe.
B.
Injected grout shall be at a unit cost per cubic foot.
C.
Installation of additional grout casings, placed under the direction of the Owner’s engineer outside the
limits indicated on _________________________drawing nos. _____________________as requiring
compaction grouting (such as areas identified as ‘marginal - may require compaction grouting), shall be
at a unit cost per foot.
D.
Mobilization and demobilization shall be a separate lump sum item.
E.
Testing may be priced as a lump sum or unit price based on the methods specified.
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