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Geotechnical News •March 2015
THE GROUT LINE
Manual has been designed to provide
guidance in all aspects of grouting and
to include the best practices and most
current technology that is being uti-
lized on USACE civil works grouting
projects. The revised manual is com-
prised of 31 chapters, 2 appendices
and is 536 pages. The new Engineer-
ing Manual provides updated informa-
tion on equipment and methods used
in current grouting practice, informa-
tion on available grout materials, mix
designs, and the benefits of the use
of balanced stable mixes for founda-
tion grouting. Guidance is provided
in geohydrology and flow modeling,
hydraulic barrier design and QA/
QC, vibration controls near grout-
ing operations, and grouting under
high head and high flow conditions.
Grouting considerations are discussed
for pre-grouting prior to cutoff wall
installations, grouting in karst geology,
blanket and consolidation grouting,
conduits, void filling, prestressed rock
anchors, tunnels, concrete structures,
and compaction and hydrofracture
grouting. Safe grouting pressures are
emphasized especially when grouting
foundations through earthen embank-
ments and an appendix is provided
with examples of pressure calculations
for use under various circumstances.
The manual also includes guidance for
source selection, the different contract
types, measurement and payment
methods and quantity estimates for
preparing grouting contracts.
The purpose of the revised
EM 1110-
2-3506 Grouting Technology
Engi-
neering Manual remains consistent
with that of the versions which have
preceded it. As stated in the Purpose
statement in the Introduction in Chap-
ter 1, “This manual provides technical
criteria and guidance for civil works
grouting applications. Information on
procedures, materials, and equipment
for use in planning and executing a
grouting project is included, and types
of problems that might be solved by
grouting are discussed. Methods of
grouting that have proven to be effec-
tive are described, and various types
of grout and their proportions are
listed. The manual discusses grouts
composed primarily of cementitious
suspensions and additives, although
other types are mentioned.” The
grouting industry has made remark-
able technological advances and the
need for the USACE
EM 1110-2-3506
Grouting Technology
to reflect the
most current state-of-the-art method-
ologies and provide guidance for best
practices for civil works projects has
resulted in this comprehensive Engi-
neering Manual.
Some considerations about the
Jet Grouting Reflow/Spoil and
its management
Last fall I had the good fortune to
participate in a couple of geotechni-
cal/tunneling conferences in which
some papers about jet grouting were
published and presented.
At the first conference one of the
papers was related to jet grouting.
Despite the overall success of the
project, there was mention of an
accident that caused the uplift of a
spillway, with cracking and dam-
age to the structure. The cause of the
accident was an incorrect procedure
used by the contractor (I don’t want to
know its name!); “it was believed that
insufficient annulus space around the
jet grout monitor was likely the major
contributor to the problem by hinder-
ing the free flow of jet grout spoil
cutting to the surface”.
A few days later, at another confer-
ence, I came across another paper
about a jet grouting project where:
“Frac-outs and up to 75 mm heaves
in the road and surrounding features
had begun to occur in the immediate
jet grouting vicinity”. Also in this case
the overall result of the jet grouting
was positive, but:
WHOA! WHOA! What is happening
to the jet grouting industry?
Why so many accidents?
Let’s stop a moment and regroup.
How can this happen? How is it that
the Contractor (I address them first,
later the design engineers) can ruin the
jet grouting name and cause damages,
in the first case, or potential dam-
ages (less problematic episode) in the
second case?
For discussion, hoping I will have
some reactions and comments from
you, here are some of my thoughts.
• Everybody who has heard the
name of jet grouting knows that
this powerful soil improvement
technique uses very high energy
created by high velocity fluids and
high pressures.
Question: what does high mean? In the
jet grouting industry today high veloc-
ity means 700 to 900 km/hr, using
pressures of 400 to 500 bars.
And the fluid flows? The flows are
not often taken into account, as for
example, in the specifications. It is the
Contractor who decides what flows
will be used to do the work. As an
example, the ASCE-G-I guidelines
mention superficially these important
variables (we are working on that!).
What do these considerations have
to do with the spoil/reflow? It is well
known that using high pressures,
high flows and high volumes of grout
mix to create the necessary energy
to construct the jet grouted element,
the process produces high volumes of
reflow composed of soil in situ and
grout mix at the ground surface.
“Spoil/Reflow is created considering
that the soil is not able to receive the
