Evaluation of Physico-Mechanical Properties of Crushed Rock Aggregates

Hazara Kashmir Syntaxial bend provide vast potential for concrete
aggregates in the region. The selection of suiTab. aggregate within
active tectonic, fragile lithologic and geotechnical environments is a
challenging approach. The present study focused on evaluating the
physico-mechanical properties of crushed rock aggregates (CRA)
that are already being mined in Muzaffarabad and surrounding areas.
For this purpose, integrated physico-mechanical with combined
petrographic and mineralogical analysis was performed on dolomite
and dolomitic limestone of the Cambrian Muzaffarabad Formation
and Eocene Margalla Hill Limestone of Yadgar section. Therefore,
samples of aggregates were collected from different quarries in
accordance with ASTM standards and their mechanical and
engineering properties were evaluated through ASTM and BS
standards. The physico-mechanical properties of dolomite and
dolomitic limestone conclude that the dolomite rocks have the
average strength against abrasion (25.12%), impact (20.75%) and
crushing (19.57%), higher specific gravity (2.76), lower water
absorption (0.65%) and higher value of sulphate soundness (1.5%).
On the contrary, the Margalla Hill Limestone which exhibits average
values of abrasion (16.93%), impact (22.03%), crushing (19.95%)
with lower specific gravity (2.63), high water absorption (0.68%),
and low values sulphate soundness (0.77%). The petrographic
investigations showed that chert 3 – 6 % and granular quartz 25 – 30
% on average are also found in dolomite and dolomitic limestone,
which causes the alkali-silica reaction (ASR) and alkali-carbonate
reaction (ACR) when used in the concrete. The XRD analysis
confirmed that both the formations dominantly contain the minerals
dolomite, calcite and quartz. It was also found that Margalla Hill
Limestone is more suiTab. to be utilised as coarse aggregate in
concrete as compared to dolomite of the Muzaffarabad Formation.
These exploitations allow recommending Eocene Margalla Hill
Limestone of Yadgar section in the production of the coarse
aggregate for concrete.