Rock with moderate strengths (20 to 70 MPa) effectively excavated by ripping
method which is considered as shallow excavation or surface striping method.
Disputed between client and contractor often occur due to the lack of proper
assessment to determine the rippabality of hard material. Practically, rippability of in
situ rock is assessed based on field ripping test that being conducted using actual
ripper dozer which is time-consuming and expensive. Therefore the assessment of
rippability of rock based on specific laboratory tests able to resolve the conflict that
occurs on ripping method. The correlation between specific energy with surface
hardness and tensile strength is chose as the material properties to assess in order to
determine the rippability of rock in this study. Few samples of Sandstone undergone
several laboratory tests such as laboratory ripping test, Brazilian's test and Schmitt
hammer test in order to obtain the required parameters in this study. The average
tensile strength (σT) obtained was 4.62MPa with a range of value from 3.19 to 7.50
MPa whilst the average rebound number (R) obtained for Sandstone was 26.6 with a
range between 19.0 and 34.0. The specific energy (SE) obtained indicates an average
value of 3.95 MJ/m3
with a range value between 1.73MJ/m3
and 6.45 MJ/m3
. The
correlation of R and σT with SE shows a relatively good relationship. Parameters of R
and σT are acceptable and reliable for assessing rippability of Sandstone based on the
value of regression coefficient (R2) which is consistence above 0.8 for both
correlation between SE, R and σT.