الفهرس 
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Abstract
The present study evaluates the geotechnical and mechanical properties
of expansive shale of Dakhla and Esna Formations. The samples are
collected from El-Balas area, west of the Nile, Qena, and from El-Quraya
area, east of the Nile, Qena, Egypt. Using Hydrometer test it is found that
Dakhla Formation from the two localities has about 73% silt, while Esna
samples from El Ballas area (EB) have 83% silt, and Esna samples from El-
Quraya area (EQ) has about 91% silt. All studied samples contain about 2%
fine sand and the other particles are clay size. The studied shale samples
have high plasticity index ranging between 15 to 27. The shale samples
tested, are classified according to unified soil classification system USCS as
MH (inorganic clayey silt with high plasticity index). However, according to
highway research board classification system H.R.B/(AASHTO), they are
classified as A-7-5 (fair to poor sub-grade).from the results it can be concluded that; the tested samples are
expansive shale (> 90% free swelling) due to their high content of clay
minerals and need to be stabilized to reduce the swelling. Three different
additives are used in the stabilization program of the studied samples as lime
(L), cement kiln dust (CKD), and mixture of L/CKD. Based on pH-test it
was founded that; the optimum contents of additives used for stabilization of
Dakhla Formation were as follow; 4% in case of using lime, 10% in case of
using CKD, and 2% lime with 8% CKD in case of using a mixture of them.
In case of Esna Formation; the optimum contents of additives are 4% in case
of lime, 10% CKD, and 2% lime with 8% CKD in case of using a mixture of
them.Proctor test according to (AASHTO, T99) is used to detect the optimum
water content (OWC) for natural and treated samples.
Unconfined compressive strength values (qu) revealed that using CKD
alone can increase the strength of the treated samples more that using lime,
however a mixture of lime and CKD can also increase the strength but using
CKD without lime is more cost effective. Also the strength increased with
increasing curing time 7 to 28 days. The strength of stabilized DB samples
increased to its maximum (1450.09 Kpa) when treated with 8% CKD and
cured for 28 days. In case of DQ qu-values increased to its maximum
(1301.89 Kpa) when stabilized with 3% lime plus 8% CKD mixture 28 days
curing time, also it reaches a high strength value (1290.56 Kpa) when
stabilized with 12% CKD and cured for 28 days. However; qu-value of EB
samples reaches its maximum (1927.05 Kpa) when stabilized with 2% lime
plus 6% CKD and cured for 90 days. Also its strength increased to (1847.47
Kpa) when stabilized with 10% CKD and cured for 90 days. While EQ
samples reaches its maximum strength (1696.97 Kpa) when stabilized with
10% CKD and cured for 90 days.Free swelling percent of the studied shale samples decreased
significantly when the samples treated with lime, CKD, and lime/CKD
mixtures. The free swelling of DB samples decreased from 80% to 2.67,
3.33, and 0% when treated with 3% lime, 8% CKD, and 2% lime plus 6%
CKD, respectively, at 90 days curing time. Free swelling of DQ samples are
reduced to minimum value when treated with 10% CKD and cured for 90
days (from 104 to 4%). Free swelling percent of EB samples are decreased
from 98.33 to 7% when treated with 2% lime plus 6% CKD and curd for 90
days. However, the free swelling of EQ samples were reduced when treated
with lime, CKD, and lime/CKD, where free swelling percent of all samples are reduced to ≤ 10%. Some of the studied treated samples has high swelling
percent, that proved the formation of ettringite mineral which considered as
expansive mineral. Ettringite is resulted from the hydration of calcium
sulfate, which present in the shale, lime, and CKD.Ultrasonic P-wave velocity test proved its effectiveness in measuring the
geotechnical properties of the studied samples. The results are very
resembles to the unconfined compressive strength values. Increasing Vpvalues
with increasing curing time proved the reducing of pore size of the
treated samples. In case of DB sample the Vp reached its higher values (1373
m/sec) when treated with 8% CKD and cured for 28 days. In case of DQ
samples Vp increased to its maximum value (1629 m/sec) when stabilized
with 12% CKD and cured for 28 days. However, Vp of EB samples reached
its maximum value (1730 m/sec) when stabilized with 10% CKD and cured
for 90 days. While EQ reached its maximum Vp-velocities (1598 m/sec)
when stabilized with 2% lime with 6% CKD mixture and cured for 28 days,
also it reached up high velocities (1519 m/sec) when stabilized with 10%
CKD and cured for 90 days