Correlations between petrography and some engineering properties of coralline limestone : a case study along the red sea coast of Jeddah, Saudi Arabia

Abstract EN

Jeddah city is located in the western region of Saudi Arabia, where Quaternary coralline limestone covers extensive areas.

Three distinct facies were recorded ; foraminiferal biosparite ; algal biosparite and ostraodal biosparite.

The allochems are mainly composed of fossils including foraminifera, algae, ostracods, gastropods, and pelecypods.

The original structures of bio-skeletons show partial dissolution and recrystallization of high Mg-calcite and replacement occurring after deposition as daigenesis processes under meteoric vadose sub-environment.

During the growth of Jeddah city, many structures were constructed over the coralline limestone.

Constructing on coralline limestone is associated with some problems, due to some special geotechnical properties of this type of soft and highly porous calcareous marine sediments.

The studied coralline limestones are generally poor foundation materials in their natural state due to weak mechanical strength and heterogeneity of their both physical and mechanical properties.

The meteoric diagenetic modifications of the original coralline limestone as well as organism borings affect greatly their physical and mechanical behavior when buildings are constructed on this rock type.

The total porosity of the studied coralline limestone samples ranges between 3.0 and 39.0 %.

According to test results of the compressive strength and point load, the studied coralline limestone is classified as very low strength.

A strong correlation existed between compressive strength and both point load strength index and drilling rate but weak correlation was found between compressive strength and both total porosity and absorption.