Being the inherent attributes of carbonate rocks, the petrographic characteristics
such as mineral composition, texture, detrital materials, porosity and microstructures are
very important factors that influence their compressive strength. Different in situ and
laboratory tests were conducted to investigate petrographic characteristics and
compressive strength of the Eocene and Miocene carbonate rocks of New Cairo City.
The results show that the uniaxial compressive strength of carbonate rocks increase with
decrease allochem fragments, idiotopic crystals, detrital materials and porosity. On the
other hand, their uniaxial compressive strength increase with increase cemented
materials, hypidiotopic crystals within the rock. The relationships of calcite cemented
materials crystal size with rock strength indicated that; the fine crystals have best
relations with rock strength parameters than the large crystals.