USE OF CRUSHED LIMESTONE FROM BAHR AL-NAJAF AREA AS A COARSE AGGREGATE FOR BITUMINOUS MIXES

Abstract

The main purpose of this investigation is to study the possibility of using crushed lime stone (which is not valid for cement manufacturing) and available in a huge quantity in Bahr Al-Najaf area as a coarse aggregate in a bituminous mixes instead of ordinary gravel which is provided from Sammerra area to improve the engineering specifications and to reduce the cost of bituminous concrete roads in many cities in the middle and south of Iraq.Two types of coarse aggregate; ordinary gravel and crushed limestone were used in this investigation. Marshall stability, extraction and stripping tests are conducted to evaluate the strength properties of the mixes, degradation of aggregates and mechanical performance of bituminous mixes under physical water effects respectively.The results indicate that bituminous mixes containing crushed limestone of Al Najaf Area as coarse aggregate are better than others containing ordinary gravel of Sammera Area because they have a higher stability and lower stripping effect due to the roughness surface particles and high voids. Flow values of asphalt mixes (corresponding to maximum stability values) satisfy the Marshall Design criteria.