A contribution to the industrial valorization of tannery waste: the case of cement industry.

The present work addresses the possibility of valorization of tannery waste incineration ashes in the cement industry. To this end, the impact of the addition of ashes at various percentages (0, 5, 10, 15, 20, 25, 30, 35, 40 and 45% in mass) on some mechanical and physical parameters of cement was e xamined: normal consistency (%), the beginning of setting (hr), the end of setting (hr), the hot expansion (mm), the resistances to compression and to bending (N/mm(2)) determined on normalized 4 x 4 x 16 cm samples. The impa ct of the treatment environment (20 degreesC and 100% of relative humidity RH, 30 degreesC and 70% RH, 45 degreesC and 45% RH) was also taken into con sideration. The obtained results reveal that the normal consistency, the be ginning and the end of setting vary linearly with the quantity of added ash es. Above an addition of ashes of 30 %, the end of setting exceeds the stan dards demanding a maximum of 10 hours. Additionally, the results indicate t hat whatever the environment treatment may be, the resistances to compressi on and to bending increase with the increase of the sample age; they vary i nversely to the amount of ash addition. The results allow to conclude that for an ash addition of 15 % and after an ageing of 30 days, the resistance to compression is higher than 40 N/mm(2), thus allowing the production of C PA 400 cement. These results also allow to conclude that samples kept in a humid environment give the best resistances to compression and to bending, by comparison with those kept in a dry environment.