Investigation of using granite sludge as filler in bituminous hot mixtures

The storing and discharge of the variety of waste products created during the production of the new products demanded by society cause huge problems such as environmental pollution, the destruction of our natural heritage, the depletion of natural resources and an increase in the daily energy consumption needed for a developing and crowded world. However, waste could be used to produce new products or as additives for existing materials or products. Using waste materials decreases the need to use natural resources and hence prevents some irreparable environmental destruction while simultaneously decreasing the impact of waste storage problems on the environmental landscape.In this research the sludge resulting from the purification of water that has been used to clean granite during cutting and polishing, consisting primarily of quartz, was tested as a filler in bituminous hot mixtures. The granite sludge was dried, milled and sieved using a No. 200 sieve, then used in production of bituminous hot mixture specimens. The waste material was used as filler in ratios of 0%, 2%, 4%, 6% and 8% to find the optimum filler ratio in the mix. A design for the bituminous hot mixture was performed using the Marshall method for each of the filler ratios, and optimum bitumen ratios were determined. Mechanical Marshall immersion tests and indirect tensile tests were performed for each of the specimens with optimum bitumen ratios. The tests results show that using granite sludge with an optimum ratio of 7.3% as filler in bituminous hot mixtures could improve the engineering properties of the mixes in wearing courses, thereby requiring a smaller quantity of natural materials, such as aggregate and bitumen, and causing less damage to our environmental heritage.

► Granite sludge useable as filler in bituminous hot mixes.
► Granite sludge could improve the engineering properties of the mixes.
► Granite sludge in road construction can contribute to the environmental protection.