Abstract:
Geotechnical tests of aggregate are important to determine strength of aggregate for
various purposes. Limestone is mostly used for the purpose of road construction because
of its good strength. Different regions of Pakistan are rich with such durable limestone.
Tests were conducted on Lockhart limestone to assess its ability to be used as road
aggregate. Plastic was added with Lockhart limestone aggregates in the proportion of 5%,
7% and 10% by weight and laboratory test were performed on the plastic-coated samples.
Results for 5%, 7% and 10% coated plastic samples are 6.05%, 9.5% and 15.2%
respectively for aggregate crushing test while non-plastic-coated aggregate show 14.5%
loss. Average value of impact test of non-plastic aggregate is 22.75%, while plastic coated
aggregate show 5.79%, 6.19% and 7.08% values. Los Angeles abrasion test show
9.495%, 11.65% and 14.25%. Marshal stability test show 2841.75, 2973.75, 3150.25 and
3162.75 values for 5%, 7%, 10% and 15% plastic content while aggregate with no plastic
show result of 2202.5. Penetration tests showed 56.5, 52.08 and 53.41 for plastic mixed
bitumen while non plastic bitumen show value of 65.5. Bitumen without plastic showed
value of 43.75 while plastic coated bitumen shows 53, 57 and 48 values. The results of
non-coated and plastic-coated samples lies within the prescribed limits defined by
standards (ASTM, AASHTO & NHA). However, plastic coated samples proved more
resistant to crushing and therefore can contribute to enhancing the road life and
performance Lockhart limestone showed good physical resistance to crushing which
prove that they can be used for road construction purpose.
