In Egypt, large quantities of coarse solid wastes are generated during the processing of phosphate
ores and quarrying operations of marble and granite rocks. These solid wastes are stored in piles
around or near mine sites, which cause many environmental problems. Various solutions have been
sought for this major environmental problem and the best solution found is recycling. However
these wastes, because of their similarity to the natural aggregate, represent a potentially useful
source of material for a variety of applications.
The main purpose of this research is to investigate the possibility of utilizing over screen reject
generated during phosphate ore processing and rock fragments of quarrying marble and granite
rocks in concrete production as full replacement of natural gravel in concrete mix. A number of tests
were carried out on these wastes to determine their physical, mechanical and chemical properties,
according to the ECP 203 of natural aggregate. So, concrete mixes using the above mentioned
wastes as coarse aggregate were done, and then tests for fresh and hardened concrete were carried
out. The mean value of uniaxial compressive strength of standard concrete cubes after 28 days of
curing was found to be in order of 193 Kg/cm2 for phosphate waste, 262 kg/cm2 for marble waste,
and 272 kg/cm2 for granite waste, which approach the conventional concrete used in building. The
obtained results proved that these kinds of wastes can be used for concrete mix in civil construction.
Admixtures may be used to improve the strength of the first one. The positive uses of these wastes
are considered beneficial from the economic and environmental points of view.