REUSE OF WATER TREATMENT PLANT SLUDGE AND RICE HUSK ASH IN CONCRETE PRODUCTION

The problem of Egyptian agricultural land is the production of Rice Husk Ash (RHA) with a huge amount and nothing made to reuse of it that made a lot of environmental problems. The average quantity of RHA produced in Egypt annually ~6 million ton and only 17% of it reused and the rest burnt causing a significant environmental problem. On the other hand, a lot of new water treatments plants (WTP) came into work producing many sludge quantities. The reuse of the sludge will reduce the burden on the environment. The competence of using the sludge generated from WTP and the RHA produced from agricultural waste was investigated in the production of concrete. Several mixes were created to check application suitability for RHA and sludge and to determine the product best application. Concrete mixes were produced with different mixing ratios of burnt RHA and sludge ash between 0 % and 30% as a cement replacement. 10% RHA cement replacement gave a very near 28 days compressive and tensile strength values to control concrete specimens. The 20% RHA replacement using dolomite as coarse aggregate attained the minimum limit for structural concrete. 10% of sludge ash replacement for the higher grades of concrete (400 kg/m3 cement content) and by using the dolomite as coarse aggregate gave suitable properties to use as structural concrete. More than 10% sludge ash replacement ratios may be suitable to use in other types of architectural concrete. Increasing cement replacement ratio slightly decreases the water absorption of RHA specimens while for sludge ash specimens, as the percentage of sludge ash increases, water absorption values of concrete samples steadily increases