Mithé Brice Mabiala Loubilou¹, Kiele Molingo Mbemba^1,, Jean Maurille Ouamba¹

Household waste management remains a delicate problem in the Republic of Congo due to the lack of household waste management infrastructure. Several wild landfills arise in outlying districts of the city of Brazzaville. The proliferation of uncontrolled landfills leads to household waste burning which essentially generates two (02) residue-type products: smoke and ashes. The objective of this study is to develop cementitious matrices containing burn ashes, sufficiently efficient to retain in their structure heavy metals contained in these ashes. To do this, we carried out static leaching tests at pH=4 and 7 and at 25°C in distilled water, cementitious matrices synthesized with different ash/cement/lime ratios (P0, P1, P2, P3, P4, P5 and P6). The static leaching tests carried out on monoliths for 30, 90 and 180 days made it possible to evaluate alteration kinetics of these cementitious matrices through cementitious matrices monitoring of leachate solution pH, of mass losses and dissolution rates. The results obtained show that the pH of all leaching solutions which contained cementitious matrices tend towards a basification causing a significant drift in the pH from the first stages of alteration at pH=4 and 7. The normalized total mass losses of cementitious matrices are higher in neutral medium (pH=7) rather than in acid medium (pH=4) except for the reference cementitious matrice P0. The P5 cementitious matrice (70% Ash + 20% Cement + 10% Lime) presents the lowest mass losses and dissolution rates, while the P0 reference matrice (100% cement) presents the highest mass losses and dissolution rates

heavy metals, cement, ashes, leaching, stabilization, solidification