Letters to the Editor

Victoria Memorial,
Calcutta, India
To the Editor:

Kevin J. Anderson's article "Granite
and Marble" in Historical Note (MRS
Bulletin, May 1993) was very interesting.
Since he touched on the use of marble for
the construction of a famous historical
monument in India (the Taj Mahal), I
would like to illustrate another Indian
example—the Victoria Memorial—a
landmark structure in the heart of
Calcutta. The marble used to build its
exterior is from the same source (from
Makrana) as that used for the Taj Mahal.
The interior of the Victoria Memorial,
however, is made of sandstone blocks.

This impressive piece of Italian Ren-
aissance architecture (see Figure 1), fea-
turing curved colonnades, was designed
by the well-known British architect Sir
William Emerson. Its construction, which
began in 1901, was completed in 1924.
This magnificent edifice was built to
commemorate the reign of Queen Vic-
toria, which ended with her death in
1901.

The deterioration of the Victoria
Memorial over the past decade has been
alarming, and has become a cause of
major concern (Figure 2). Having had the
privilege of carrying out an investigation
to determine the cause of its deterioration
(UNDP TOKTEN Program1), I fully con-
cur with Anderson's view that the wide-
spread use of fossil fuels is, to a large
extent, responsible for gypsum recrystal-
lization in stone (Figure 3). This type of
secondary gypsum is expansive in
nature, and can cause severe damage to
the stone. In addition, the city of Calcutta
supports one of the highest urban popu-
lations (exceeding 10 million) in the
world today. In this respect, reference is
made to Fassina's report,2 which posits
that in industrial or urban areas, human
activity results in the constant emission
of sulfur-bearing compounds, which also
contribute to the degradation process
(Figure 3). Vehicular traffic in the city of
Calcutta today totals nearly half a mil-
lion.

The Memorial complex used to be dot-
ted with large evergreen trees that in a
very definitive way formed a green belt,
and a protective cushion against environ-
mental pollution. The indiscriminate
chopping down of these trees during the

Figure 1. A view of Victoria Memorial,
completed in 1924, a fine example of Italian
Renaissance architecture undergoing dete-
rioration due mainly to environmental
pollution.

Figure 2. A scanning electron micrograph
of a deteriorated calcite crystal (in marble),
split open along its cleavage planes.

Figure 3. Recrystallized gypsum crystals in
sandstone, viewed under a scanning elec-
tron microscope (SEM).

past decade, to introduce a "son et
lumiere" show on the memorial, has
aggravated the problem still further.

Also of significant interest is the fact
that parts of the sandstone blocks inside

Figure 4. An affected quartz crystal in the
sandstone. Its edges have been corroded,
and part of it has decomposed.

the building have been even more sev-
erely affected. Large efflorescent patches
due to the recrystallization of expansive
salts, gypsum in particular, have resulted
in spalling and exfoliation. The host min-
erals in the rock have also been damaged
(Figures 3 and 4).

Absorption of salts by natural rocks
depends on their porosity. Mercury
porosimetry tests show that sandstone is
porous, compared to marble. It is there-
fore more prone to chemical attack.

Calcutta is close to the Bay of Bengal,
so the salt-laden sea breeze combines
with the atmospheric sulfur dioxide,
which penetrates the sandstone to pre-
cipitate as gypsum, thenardite (Na2SO4),
and its decahydrate form, mirabelite
(Na2SO4»10 H2O). The high humidity
(RH ranging from 90 to 98%) and warm
temperature (15 to 35°C) promote the sal-
ification process.

Let us hope that the authorities will
take note of the rapid deterioration now
in progress, and act before it is too late.

Shondeep L. Sarkar
Research Professor

Civil Engineering Department
Universite de Sherbrook

Sherbrooke (Quebec) J1K 2R1 Canada

References
1. S.L. Sarkar, A.K. Bhadra, and P.K. Mandal,
"Microstructural investigation of mortar and
stone deterioration in Victoria Memorial,
Calcutta," submitted to Materials and
Structures (RILEM, 1993).

2. V. Fassina, "Environmental pollution in
relation to stone decay," in Durability of
Building Materials 5 (1988) p. 317. •

1993 MRS FALL MEETING - See pages 6 6 - 6 8 for information.

MRS BULLETIN/AUGUST 1993
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