Determination of ideally slake
durability index (SDI) value depending
on number of cycles
Journal Name:
- Dicle Üniversitesi Mühendislik Fakültesi Mühendislik Dergisi
Keywords (Original Language):
| Author Name | University of Author |
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Abstract (2. Language):
Slake Durability Index test is widely used in rock
mechanics, engineering geology and the selection
and evaluation of natural building material. In
general, the aim of this test is to provide an index
that is related to resistance of rocks against
degradation when it is subjected to two Standard
cycles of wetting and drying. The slake durability
test was suggested as a standard test for rocks by the
International Society of Rock Mechanics and also by
the American Society for Testing and Materials.
The slake durability index (SDI) can be considered
to be one of the most important properties for
shales, clay-bearing rocks and similar weak rocks. A
number of parameters have an effect on the slake
durability index value. Such affects can be listed as;
mineralogical composition of rocks, number of
wetting and drying cycles, the character of the
experiment solution, degrees of surface roughness
and so on. Tests omitting any of the factors listed
above would lead to erroneous results. Among these
parameters, it can be said that the geometrical
shape of the rock samples used in the test is an
important one. The ASTM and ISRM test methods
mention that the shapes of rock samples should be
close to spherical as much as possible, each having
a mass between 40 to 60 grams. Nevertheless,
preparation of nearly spherical samples could be
time consuming or sometimes be very difficult. It
should be also stated that being nearly spherical is a
subjective matter, which changes from person to
person. In this study authors have proposed a sphere
test sample preparation method in order to eliminate
this subjective matter. The application of this
method makes possible the preparation of equalsized
and weight, and smooth surface sphere test
samples for SDI test.
The white tuff is selected for this study because of
the fact that tuff and ignimbirites type rocks were
used to build historical monuments in the past, and
are nowadays being used as decorative material in
Turkey thanks to their softness and easy processable
nature. White tuff block samples having fresh,
slightly and moderately weathering grades were
taken from face and stock field of an active tuff
quarry located near to Derbent village of Eskisehir
province. K, H and W symbols were used for fresh
white tuffs, slightly and moderately weathering white
tuffs, respectively, in this study to illustrate each
weathering grades. Four different test sets for fresh
tuffs were prepared; rounded sample sets according
to standards, three sphere sample sets. The weights
of sphere test samples in three sets are about 40, 50
and 60 g each. Six different test sets for slightly and
moderately weathered tuffs were prepared as sphere
test samples which have about 40, 50 and 60 g each.
The SDI tests for 12 cycles were carried out on all
white tuff test sets. The SDI values of sphere test sets
were compared with the SDI values of K_Y test set.
The SDI values of K_60, H_60 and W_60 test sets
were found to be higher than the SDI values of K_Y
and other sphere test sets prepared from weathering
tuffs. Therefore, these test sets were ignored to
determine the SDI values. Because it has been
obtained similar results for H_40 test set, it was
decided that ideal index values could not been
determined from the test sets which have about 40 g
each.
According to the standard two-cycle SDI test, the Id2
value of W_50 test set was found to be 95.39 %. It is
higher than the index value of K_Y test set, 94.39 %.
Similarly, the SDI values of W_50 test set up to 8-
cycle were found to be higher than the index values
of K_Y test sets. The SDI values of K_50, K_Y, H_50
and W_50 test sets at the end of twelfth cycle were
determined to be 72.48 %, 69.03 %, 67.24 % and
64.67 %, respectively. In this case, the SDI values
were able to define the weathering characteristics.
Then, the SDI values of K_50, K_Y, H_50 and W_50
test sets were subjected to regression analysis. The
Id2 and Id4 values of H_50 have been estimated as
93.47 % and 88.16 %, respectively. The Id2 and Id4
values of W_50 have been estimated as 92.82 % and
86.54 %, respectively. As a result, it has been
concluded that it is appropriate to use these index
values in engineering problems, as ideal index
values.
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Abstract (Original Language):
Suda dağılmaya karşı duraylılık indeksi (SDI) deneyi, zayıf ve killi kayaçların ıslanma ve kuruma çevrimleri
sürecinde, aşınmaya ve ayrılıp suda dağılmaya karşı gösterdiği direnci belirlemekte kullanılmaktadır. SDI
deneyi sonrasında bu direnci belirleyen bir indeks değeri hesaplanmaktadır. Ancak deneyde kullanılan örnek
parçalarının şekli, ağırlığı, boyutu ve yüzey pürüzlülüğü gibi indeks değerini etkileyen birçok etken vardır.
Bu çalışma kapsamında taze ve yüzeysel bozunmaya uğramış beyaz tüflerden küre şekilli, eş farklı boyutlu,
eş farklı ağırlıklı ve pürüzsüz yüzeyli deney örnekler üzerinde SDI deneyleri yapılmıştır. Deneyler sonunda
deney örneklerinin kütle ağırlığı 50 gr olarak belirlenmiştir. Ayrıca bu etkenlerin SDI indeksi üzerindeki
etkisi çevrim sayısına bağlı olarak da araştırılmıştır. Bu deneyler sonucunda beyaz tüfler için çevrim
sayısının da SDI indeks değerlerinde etkin olduğu ortaya konulmuştur. Standartlarda önerilen 2 veya 4
çevrimlik SDI deneyinin beyaz tüf için yeterli olmadığı, çoklu çevrimden sonra ideal indeks değerlerine
ulaşılabileceği sonucuna varılmıştır.
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