Geotechnical Properties of Cambrian Dolomite, Abbottabad Formation, Hazara Kashmir Syntaxis and Azad Kashmir, Pakistan

Abstract

The Geotechnical and mineralogical characteristics of Abbottabad Dolomite have been investigated to evaluate the rock as concrete aggregate. The study extent at longitudes 73° 26ʹ-73° 30ʹ and latitudes 34° 12ʹ -34° 24ʹ with a total covered area of 140 sq.km from district Muzaffarabad (Azad Kashmir, Pakistan) and Abbottabad district (Khyber Pakhtunkhwa, Pakistan). From Lohargali to ChattarKalas along Neelum and Jhelum rivers was mapped at the scale of 1:12,500. The main objective of the study to exploreand interpret all the physical and geotechnical properties of dolomite as aggregate, which is exposed in the area and presently being used for buildings construction, road, airports and bridges etc. The study concentrates on the various mechanical and mineralogical properties of the Dolomites as a construction material to evaluate the environmental impact, as well as the ground properties. As well as, mineralogical composition of dolomite was also investigated to know the weathering effects in acidic and alkaline environments. To explore and extract specific portion of the study area survey of Pakistan Toposheet # 47-F/7 with scale of 1: 12500 were used. During the field work, number of traverses were made to explore the relevant area and samples were collected according to color, texture, structure, joints and thickness of the rock bed. Total number of 4 samples about 40 kg mass were collected according to British standards. Standards (B.S) from different sampling locations of the study area, such as MakriNalah, ShiwaiNalahandYadgar. Dip, strikes, joints, and cracks were plotted on site for the preparation of geological map. From results, all the tests (such as Crushing Value, Impact Value, Los Angele’s test, Specific Gravity, shape of particles and water absorption) arenot comparable with B.S (British Standard).At places rocks are highly crushed and deleterious material in the rock aggregate are high. The alkali-silica reactions in dolomite involves disordered form of silica, particularly Chert and Iron. The presence of Cherty minerals and silica in dolomite is not desirable elements and create serious complications during the reactions between alkalies and silica. The result of elements reaction gives rises magnesium-silicate gel, which swells and cause cracks in the concrete/actual shape. The tensile strength is also reduced and gel material appears as white exhalation on the surface of the concrete. The alkali-silica reaction occurs in specific areas of MakriNalah, ShiwaiNalah and Yadgar area. Reserves of the Abbottabad Dolomite as geo-material at different localities were also estimated for the mine purposes.