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Geotechnical News • September 2018
THE GROUT LINE
causing some stones to jut out. Fur-
thermore, the stone base supporting
the 16-ton Moses statue was in danger
of collapsing. The Father Matthew
statue had been struck by lightning in
1910 and repaired with an iron and
metal pin anchor system, which had
succumbed to corrosion. The city
considered it the most threatened of
the statues.
A preliminary comment during the
initial site visit was: “The fountain
is in pretty bad shape” and two main
goals were identified. One was to
inject grout beneath the Moses statue’s
stone base. The second was to pump
grout into various points to support the
granite steps surrounding the marble
fountain and four satellite statues.
The monument’s location in the center
of a traffic circle further compli-
cated matters. It was obvious that the
fountain had been damaged by errant
vehicles. There were, in fact, several
such incidents during the repairs,
which prompted the erection of jersey
barriers around the perimeter.
The gist of the project was to fill
the void spaces in the statue to stop
settlement and rehabilitate the affected
structures and the logical solution was
to use high-mobility grout under low
pressure – 25 psi or less.
A pattern of drilled holes was chosen
to try to intercept the spider web of
interconnected voids.
Masonry and grouting go hand
in hand
Masonry and grouting contractors
worked closely since their respective
scopes were closely interwoven. Daily
logistical coordination was required
for tasks such as moving and reset-
ting stones; pointing stone joints;
coordinating access to the scaffolding;
providing access for grouting ports;
and protecting the fountain throughout
the restoration. Making sure grouting
ports were available was key to avoid-
ing downtime. The grouting contractor
worked continuously with the mason
to coordinate their installation. The
mason would also have to point the
stone joints prior to injecting grout
into Moses’ stone base.
Grout mix
Instead of using pre-confectioned
grout mixes, a custom mix design was
proposed, based on Type 1 Portland
Cement, Undensified Silica Fume,
water, a stabilization and shrink reduc-
tion admixture, and a water reducer.
The final composition to produce an 8
CF batch was 6- 94 lb Type I Portland
Cement, 1- 50 lb bag of Undensified
Silica Fume, ½ gallon of water reducer
and 33 gallons of water.
Moses in the front.
Grout Fairmount Fountain.
Grout Fairmount Fountain.
