Foundation Specialists Inc. [FS] had developed in 1983, in the Philippines, its own methods and tools
for the execution of Jet-Grouting adapted to the prevailing local soil conditions, i.e. high water
table, soil formations prone to liquefaction during seismic events, and a relatively high seismicity.
Before Proposing
the use of the FS Jet Grout Technologies to Clients, FS had conducted extensive trials during the whole year
1983, in testing fields chosen for the very poor soil conditions, (a) within the Reclamation Area at that time
created by the Construction & Development Corporation of the Philippines (CDCP), (b) along the reclaimed portions of CDCP- FS R-10 Road
Project in Manila & Navotas, (c) in the (at that time) swamps of Dagat Dagatan in Navotas MM, d) in the area
of National Steel Corporation Plant along the shores of Iligan Bay. After 1 week curing period, the
Jet-Grout Columns and Soil-Cement Piles were cored and the cores tested in Laboratory for compressive
strength, shear strength and cement content . Third Party Consulting Engineers were invited and witnessed
the trials
The results of tests conduced on the
treated soil were then compared with the results of field and Lab Tests Conducted on the original untreated soil, to
evaluate the degree of improvement produced by Jet-Grouting.
Initially, in 1983, FS had developed three Jet-Grout technologies
and related tools, 1) Mechanical Deep Mixing “”FS SOIL-CEMENT COLUMNS”” with
one fluid component , i.e Cement Grout to be jetted from within the mixing tool ; 2) Two Components
FS Jet-Grout to be directly Jetted by the “Monitor” into the surrounding soil, Water
jetted at very high speed , and Cement Grout likewise jetted at high speed from two distinct nozzles
of the Monitor; 3) Three Components FS Jet-Grout also to be directly jetted from 3 distinct
nozzles of the Monitor, Water, followed by Cement Grout and by compressed air, where the compressed air has the
function of extending the reach of the cement grout into the surrounding ground fractured by the water jetting. The
Procedures developed by FS found immediate applications in various industrial projects, in bridge foundations
retrofitting, to control local scouring around bridge foundations, in buildings foundations on liquefiable soils.
The FS Mechanical Deep Mexing Method (FS Soil Cement Columns) was found to produce exceptionally good results not only
in sandy and silty formations, but also for water saturated clay, which produced a steady request of the treatment. After
a good number of successful applications, the three FS developed methods were described by a “paper” of Dr. Armando
Cazzola, published by the Philippine Institute of Civil Engineers (PICE) Journal in 1985.
Both Jet Grout Methods, 2
and 3 are most indicated for “Alluvium” formations. i.e. formations composed of fines and gravel, pebbles and
boulders, where the fines are floated and removed upwards and above ground by the high speed water jets,
and replaced by cement grout to eventually form a sort of cyclopean concrete. Jet Grout Method 1 is
instead most indicated for clay, silt, sand formations , which are mechanically mixed, combined
with cement grout .
Methods 2 & 3 float and remove as liquid mud most or all of the fines, and replace it with cement grout, while
Method 1 mixes the in situ soil with Cement Grout. In silt and clay the quantity of soil to be removed
to disposal is mostly equal to the volume of grout injected, while in sandy soil formations with high percentage
of voids the soil to be disposed is near zero in volume, since the cement grout displaces interstitial water and fills the
voids so produced.
For FS
Soil- Cement Columns the most common diameter is 800MM, but the Method can be very efficiently executed
also with smaller and larger diameters. The diameter of the mixing tool used for the FS Soil Cement Columns is exactly
the same as the diameter of the columns specified by the designe. The strength of the improved soil is verified by coring
the columns and testing the cores in Lab by Unconfined Compression Test.
Proper design pattern of jet grout eliminates
the potential for liquefaction of the areas treated, so the FS Soil Cement Columns is the designers’
favorite system for Tanks Foundations in Tank Farms , Warehouses, Bridge Approaches, Slope
Protection, Excavation Support, Buildings’ Foundations, Underpinning of Structure, Cofferdams, Pre-consolidation
in preparation for Large Diameter Piles or DW in unstable soil formations; Bottom Plugs to seal bottom of pits, and as FS
Composite Soil-Cement Columns (with “I”-beams embedded in it), used as Diaphragm Walls, Fs
has successfully completed already hundreds of jet grout projects, in various Countries, with FS Soil
Cement Columns having the Lion’s share of it.
1991 - TWO ADDITIONAL JET_GROUT METHODS WERE ADDED :
In 1991, while FS was
the General Contractor constructing the 4th ADB “Dapitan Manucan Road
Project and the Polo Bridge in Zamboanga Del Norte, part of the work was to stop the sinking and rehabilitate several
Box Culverts which were under-scoured by heavy floods. To restore proper ground support to the under-scoured Box
Culverts, FS proposed to use Jet Grouting. Soil Cement Jet Grout required the opening of
too many large holes on the top and bottom slabs of Box Culvert, to allow the passage of the mixing tool, and we
decided to consolidate the soil under the Box Culverts with a “modified” FS Types 2 and 3 Jet Grout.
The “modified Method consisted of the original method minus the high speed water jetting. The scoured sandy
soil underneath the Culverts was then subjected to a high speed Jet Grouting of Cement Grout . The speed of the
Grout Jets was increased by employing a pump which produced high speed and large volume of grout suitable
to perform at once the fine fragmentation of the soil and the impregnation of the”fragmented” soil by Cement Grout
The results were found to be excellent and FS proceeded to consolidate the ground underneath the Box Culvert with
that method which was dictated by local conditions . It was thus that the Methods 4 and 5 were created
and immediately applied, with success.
Method 4) , Jetting at very high speed One Fluid to break and impregnate
the soil formation i.e. jetting at high speed Cement Grout only, to breaks and impregnate the soil.
Method 5), of Jet-Grouting is
a variant of the Fourth Method, with the addition of the introduction of Compressed Air, which sharply increases the reach
of the Cement Grout and thus creates Jet- Grout Piles of considerably larger diameter than those created by Method No.4.
Foundation Specialists, Inc. is ISO 9001_2015 Certified
