A. L.
Construction
Co Ltd.
Palm Reef Resort CFA
Pile Installation CFA Piling
System
Production,
Testing,
Analysis and
Reporting
Harvest Caye
Pile Testing
Placencia
Peninsular,
Stann Creek
District,
Belize, C. A.
Palm Reef Resort
Pile Testing
November 2014
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Introduction
This brief report documents a demonstration installation of uncased reinforced concrete
bored piles produced by A. K. Aggregates & Concrete supplies of A. L. Construction Co. Ltd.,
located at Mile 25, Southern Highway, Stann Creek District, Belize, C. A.
It summarizes pile test data from the installation of 9 test piles located as follows:
Harvest Caye (7 locations)
Palm Reef Resort (2 locations)
This ephemeral investigative report was prompted by high demands for concrete foundation
piles on the Placencia Peninsular and its vicinity in the Stann Creek District, since most
precast / pre-stressed reinforced concrete (RC) piles are produced in the Belize and Orange
Walk Districts at locations, some 150 to 200 miles from the peninsular area.
The importance of exploring alternatives for reliable, affordable and rapid production
methods has long been a consideration and some ad-hoc developments have been
attempted but without professional input.
The System
The system being reviewed is based on a methodology locally refined by Albert and Klaas
Loewen of A. L. Construction Ltd., which is a reputable aggregate and concrete supply
company located in the Stann Creek District.
The system is an augured pile installation methodology that is internationally recognized as
the Continuous Flight Auger Pile (CFA Pile).
The system comprises a combination procedure that
affords the following elements in a single process:
Position and confinement
Augur drilling and extraction of spoils
Tremie concrete placement via auger core
Steel reinforcement cage placement with cover
spacers and
Concrete vibration via cage induction
The equipment used is an Auger Adaption Rig
attached to a CAT Excavator boom that is hydraulically
controlled and capable of vertical and inclined drilling
to a depth of 40 ft at virtually any location.
The system’s main power source is a track driven Cat Excavator 320 C, capable of
traversing difficult terrain conditions and is “self-supporting” in unforgiving slopes or soil
condition, since it carries accessories for earth moving, lifting, spreading and cutting as
necessary.
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The same connection cleat that supports the Auger Rig also supports a Pile-drive Hammer
Rig with quick set-up connections and fold-and-carry capability.
Typically, concrete of minimum 3,500 psi is targeted and up to 5,000 psi is possible if
required. Generally, no additives are required as a 6” slump is used to afford required
workability to ensure efficient pumping and steel reinforcement placement is problem-free.
Steel reinforcement cages are manually prepared in advance to design specification and
brought to site. The Rig also has a block & tackle gusset for hoisting and lowering the cage
reinforcement, thus requiring limited manpower to guide the placement of the cage in
freshly concreted piles.
I unique semi-circular RC centralizer spacer is used to ensure targeted steel cover while its
profile minimizes disturbance to freshly excavated earth walls during steel cage insertion.
A 2” poker vibrator can be temporarily attached to the steel cage during cage descend to
aid in placement, concrete compaction and entrained air removal. (Was not used during
these pile trials)
The CFA Pile production described above is being introduced formally by this report and the
subject test data interpretation will be elaborated below.
Use and Application of CFA Piles
The use of powered auger pile dates back to the early 1900’s but professional installations
in Europe and USA became wide spread in the early 1980’s. The first large scale CFA pile
project application was introduced in Western Canada in 2005, where many full scale load
tests were performed.
The use of bored piles is popular in the Spanish Lookout area of Belize and has been in use
for many years. Similar systems are used on Islands / Cayes off the Belize and Stann Creek
Districts but jetting seems more popular where sand is dominant.
Many edifices and civil structures on the Placencia Peninsular were successfully constructed
on CFA piles by the Loewen Brothers, including structures at the following project locations;
to name a few:
Thunderbird Marina
Saddle Caye
Placencia Caye
Roberts Grove lagoon side Housing Project
Crimson Park, Placencia
Vista Cove, Placencia
Plantation near Caribbean Way
Sanctuary Belize, Stann Creek District
Hopkins & Sittee Point
This local technological development in the construction industry has evolved to a point
where mass production of these piles is feasible professionally and the proven combination
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of the use of a tailored diesel excavator with augering attachments used in tandem with a
concrete pump and a concrete batching truck has been applied successfully on scores of
projects to date with no report of subsidence or foundation issues.
This method is applicable and recommended for projects as follows:
Sea and river defence installations
Mast and tower foundation
Multi-stored edifices such as:
o Homes, Hotels, Offices, Ware houses, Institutional buildings, Retaining
structures and
o Any foundation system requiring single or grouped piles in areas where
bedrock or firm bearing strata is located at prohibitive depths or where
friction rather than end bearing is inescapable due to soil peculiarities.
System Comparison
Every system has advantages and disadvantages and this system is no exception.
CFA piling possesses the following key characteristic pros and cons when compared with
driven piles:
Advantages
o No harmful vibration
o Low noise levels
o No temporary / permanent casings required
o Speed of installation
o Lower unit cost
o Piles can be driven within 24 hours of commencement notice
o Pile reinforcement not needed for entire pile length
Disadvantages
o Difficulty penetrating very hard layers without toothed cutter
o Less firm refusal in end bearing scenarios
o Steel reinforcement centering may be challenging
o More technical supervision required on site
o Require specialist piling contractor
Clearly the advantages outweigh the disadvantages. For further reading see guidelines of
the International Code Council (ICC) as adopted by the 2007 Florida Code and a Jeff Grieder
presentation entitled Continuous Flight Auger Piles.
Testing
This document records the preliminary results of pile testing conducted on two proposed
building sites at a time when there were no commitment to use the system at these
locations.
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The piles were prepared and installed as follows:
Harvest Caye - 1/11/2014-6P
Palm Reef Resort - 3/11/2014-1A
Harvest Caye Site
Seven (7) piles were casted by the CFA method on 1/11/2014-6 and pile caps with
pedestals installed on the 10-11/11/2014.
After 25 days of curing, piles were prepared for testing.
Load tests were conducted on all 7 piles on 26/11/2014-3A using an ALC built Pile Driver
with a 4,400 lbs solid steel hammer in a drop hammer rig, complete with hydraulic wench
and electrically actuated pneumatic release latch clutch. (See attached data sheet for pile
driving records)
Test results revealed the following variations:
Estimated Ultimate Resistance (Engineering News Record Formula): 12.6-33.7 tons
(Ave 24.7 tons)
Estimated Ultimate Resistance (Danish Formula): 11.6-54.7 tons (Ave. 30.0 tons)
Allowable Total Loads (2007 Florida Building Code): 9.2-17.5 tons (Ave. 12.1 tons)
Higher results were obtained near the proposed warehouse and restaurant while lower
values were in the vicinity of the proposed wooden stores.
Drop hammer lifts varied between 3 and 5 ft and average penetration / blow was 0.264”
over a range of 0.025-0.525”.
Piles varied in length from 20, 30 and 37 ft and all piles were drilled with a 14” auger and
reinforced with 5#5 with #3 @ 3” (10ft) with #3 @ 6” to approximately 1/3 cage length.
Factor of Safety was computed between 1.3 and 3.1 by the ENR Formula and between 1.1
and 5.0 using the Danish Formula. This formula is preferred by some engineers since it
considers the in-situ pile mass, geometry and modulus of elasticity.
It was noted that the highest pile capacity was recorded near to the proposed boardwalk /
warehouse. (EUR Danish)
Palm Reef Resort
Two (2) piles were casted by the CFA method on 3/11/2014-1P and pile caps with pedestals
installed on 12/11/2014-5.
After 23 days of curing, piles were prepared for testing.
Load test was conducted on both piles on 26/11/2014-3P using an ALC built Pile Driver with
a 4,400 lbs steel hammer in a Drop Hammer Rig, complete with hydraulic wench and
electrically actuated pneumatic release latch clutch. (See attached data sheet for pile driving
records)
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Test results revealed the following variations:
Estimated Ultimate Resistance (Engineering News Record Formula): 44.9-49.1 tons
(Ave 47.0 tons)
Estimated Ultimate Resistance (Danish Formula): 65.7 -68.0 tons (Ave. 66.9 tons)
Allowable Total Loads (2007 Florida Building Code): 14.6-17.9 tons (Ave. 16.2 tons)
The higher result was obtained to the north while the lower value was at the south location.
Drop hammer lifts varied between 4 and 5 ft and average penetration / blow was 0.088”
over a range of 0.075-0.100”.
Both piles were 37 ft in length and piles were drilled with a 14” auger and reinforced with
5#5 with #3 @ 3” (10ft) with #3 @ 6” to approximately 1/3 cage length.
Factor of Safety was computed between 2.8 and 3.1 by the ENR Formula and between 3.7
and 4.7 using the Dutch Formula. This formula is preferred by some engineers since it
considers the in-situ pile mass, geometry and modulus of elasticity.
It was noted that these relatively high pile capacities were recorded at locations that have
clay at the terminal depth.
Conclusions
It is hereby concluded that this tested pile system is a formidable methodology that should
be respected as a pile installation alternative that is technically astute and practical with
cost and time saving benefits.
Its piles can be installed to achieve significant load capacities and more designers and
builder’s should consider its application, particularly where its advantage brings economics
to a proposed implementation.
The tests performed were witnessed by technical representatives of the respective project
sites, at least one of their principals and by the undersigned engineer.
The result presented herein represents an independent evaluation of the process and end
results, and was documented with full objectivity and with the scrutiny of others; some of
whom are unreceptive to the introduction of a relatively new process despite its quantitative
merits and proven success.
The fact is, that similar pile systems have been in use on the Placencia Peninsular over the
last decade on large structures with good initial review, though there have been some
issues. Nevertheless, the unassailable success record of the ALC installations is testament to
the viability and professional acceptance of this system, particularly since hundreds of CFA
piles are in use and displaying satisfactory performance. An informal poll conducted
revealed a significant number of designers, builders and investors who either desire to use
the system or intends to continue its use on future projects.
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Recommendations
General
It is here recommended that this foundation support system be assessed by the engineers,
architects and civil engineering builders of Belize with a view to incorporate its application
into the norms of piled foundation of structures, particularly where site conditions makes it
a favourable alternative.
It is also recommended that the system continues to be tweaked to optimise its reliability,
effectiveness and competence as a piling system that is expected to survive more than a
century of useful life.
Technical
Piles should have a minimum of 4 longitudinal bars and steel area should exceed 0.8% of
pile section. The allowable design stress in the concrete of these drilled uncased piles should
not exceed 33 percent of the 28-day specified compressive strength.
The allowable compressive stress of reinforcement shall not exceed 34 percent of the yield
strength of the steel and the pile length should not exceed 30 times the average diameter.
The minimum diameter should be 12”.
All these requirements were exceeded in the trials that are the subject of this report.
Limitations
It should be noted that the author of this paper was invited merely as an observer and was:
Not present for the casting of the piles at the Harvest Caye location.
Not privy to any of the following:
o Geotechnical reports
o Topographical survey
o Vicinity cavern study
o Proposed plans for the projects
Had no prior discussions before the operation commenced nor after the tests were
performed with:
o A L Construction
o Technical or proprietorship individuals of the two subject sites
The concreting works on Harvest Caye were conducted on a day when the undersigned
engineer was unavailable. However, all other aspects of the pile preparation and testing
were witnessed and documented with photograph reference to every step of the process.
Eng. Cadet A. Henderson
Henderson Engineering Consultancy
#4 University Cr., Belmopan, Belize, C.A.
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Mosaic 1: Pile Installation at Palm Reef Resort
Steel reinforcement cages at main base with CFA augering equipment coupled with
#3@3” ready for use. Note bottle reference. concrete pump and concrete batching truck.
Auger cleaning and spoil relay as excavated Steel reinforcement cage being hoisted for
material is brought to the surface. inserting into fresh concrete in pile.
Men assisting with the clearing and removal of Clean up in progress after concreting. Specialist
augured material from pile depth.
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pile contractor seen leaving the drill site.
Mosaic 2: Pile Load Testing at Harvest Caye
Positioning rig and equipment for load test Contractor Albert Loewen measuring
pile driving on the Island. penetration with Site Superintendent.
Verification and summary measurements being View of shattered pile after pile test completion
taken on a pile after 25 hammer blows. showing fractures and spalls.
Klaas Loewen marking a TBM for pile penetration View of total equipment set-up showing CAT
reference measurements near a boardwalk. Excavator and pile driving Rig attachment.
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Mosaic 3: Pile Load Testing at Palm Reef Resort 2
Pile driving Rig prepared for testing. Note Use of laser level sensor to measure
excavation around cap to remove surcharge. penetration in challenging location.
Extremely shattered pedestal head after testing. North pedestal during testing. Note hammer raised
Pile hammer on the heavy side at 4, 400 lbs. full 5 ft before impact. South pile in foreground.
Battered pedestal after pile driving. Note exposed Setting up laser tripod for monitoring. Note
steel rebars. Extra driving only for experiment. spectators and heavy transport trailer.
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Test Data Set for CFA Pile Drive Hammer Tests at Harvest Caye and Palm Reef Resort
Average Resort
Hammer Uncased CFA Bored Pile Computed Loads
Site Penetration
Ref Date Location Comment
Element (Last 5 Base Allowable
Wt Fall Dia. Length Rebars EUR (ENR) EUR (Danish) FSe FSd
blows) Soil (FBC)
lbs ft ins ins ft lbs tons lbs tons lbs tons
Harvest Caye
26/11/201 Harvest Coral /
1 Pool 4400 4 0.250 14 37 28160 12.6 50285.7 22.4 52643 23.5 1.8 1.9
4 Caye Standard R1 Peat
27/11/201 Harvest Coral /
2 Restaurant 4400 4 0.160 14 30 30345 13.5 67692.3 30.2 80126 35.8 2.2 2.6
4 Caye Standard R1 Sand Shattered
28/11/201 Harvest Wooden
3 4400 3 0.275 14 20 ? 20706 9.2 35200 15.7 36908 16.5 1.7 1.8
4 Caye stores Standard R1
29/11/201 Harvest
4 Boardwalk 4400 3 0.075 14 20 Sand 24558 11.0 75428.6 33.7 122623 54.7 3.1 5.0
4 Caye Standard R1 Shattered
30/11/201 Harvest
5 Ware house 4400 5 0.125 14 37 Clay 39111 17.5 97777.8 43.7 121781 54.4 2.5 3.1
4 Caye Standard R1 Shattered
01/12/201 Harvest
6 Ware house 4400 4 0.525 14 30 Clay 23082 10.3 28160 12.6 26039 11.6 1.2 1.1
4 Caye Standard R1 Shattered
02/12/201 Harvest (Below
7 4400 4 0.438 14 37 ? 24487 10.9 32744.2 14.6 30948 13.8 1.3 1.3
4 Caye ground) Standard R1
Average values: 0.264 30 27207 12.1 55327 24.7 67295 30.0 2. 2.4
Palm Reef Resort
26/11/201 High-rise
8 Palm Reef 4400 5 0.100 14 37 Clay 40000 17.9 110000 49.1 147253 65.7 2.8 3.7
4 Hotel Standard R1 Shattered
27/11/201 High-rise
9 Palm Reef 4400 4 0.075 14 37 Clay 32744 14.6 100571 44.9 152281 68 3.1 4.7
4 Hotel Standard R1
Average values: 0.088 37 36372 16.2 105286 47.0 149767 66.9 2.9 4.2
Standard R1: 5#5 w/ #3@3" (10') w/ #3@6"
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