Strukturbildung in der mineralischen Komponente von Deponiedichtungen

Abstract

The physical performance of the mineral components in seals of landfill sites was investigated with special reverence to clayey substrates. As a main feature of these sealing substrates the interfering aspect of the formation of pore structures, which are caused by mechanical processes as well as by hydraulic processes, is the limiting factor using these seals in practice.During the seal installation primary interaggregate pores are closed by mechanical consolidation while the subsequent hydraulic consolidation causes a new formation of secondary interaggregate pores or shrinkage cracks, respectively. Both, primary and secondary interaggregate pores are macropores and decrease the efficiency of seals.With a new developed Proctor Test mineral substrates with varying consistency were stressed by mechanical forces as well as by hydraulic forces, which leads to the states of equal mechanical (Ea) and hydraulic (h) consolidation energies, expressed in Ea- and Ea-h-isoenergetics. The volume of primary and secondary interaggregate pores, important for the sealing quality of the clayey substrates, can be concluded from these isoenergetics for different water contents.The water content of German seal compounds has to meet the standard Proctor Test (DIN 18127) at application time. In contrast to the newly introduced Proctor Test the standard Proctor Test simulate only mechanical consolidation processes. Considering the hydraulic consolidation processes as well, the appropriate water content of mineral substrates with plastic properties is reduced. For the examined clays with medium and strong consistency this amounts in about 7 weight-% below the plastic limit of Atterberg. In addition, the formation of primary and secondary interaggregate pores is also affected by the mechanical forces.The concept of an extended Proctor Test including the aspect of hydraulic consolidation has lead to an extension of the Atterberg limits.