Application of alkali-activated industrial wastes for the stabilisation of a full-scale (sub)base layer

Abstract

An increasing interest in the development of alternative solutions based on the use of wastes and res- idues in the context of soft soils improvement has been observed in the last few years. Most of such research is related to the laboratory characterization of the soil-binder or soil-reinforcement mixtures. However, the viability and impact of the construction process associated with these alternative solutions, as well as the effect of the in situ curing conditions on the mechanical and durability properties of the improved soil cannot be properly assessed in the laboratory. The present paper describes and examines what is, to the best of the authors knowledge, the first full-scale attempt to apply alkali-activated fly ash to the stabilisation of a (sub)base layer. Different types of alkaline activated cement were tested, and soil- cement and soil-lime mixtures were also used, for comparison purposes. An 80 m long (2.5 m wide) full- scale trial was built, divided into 5 sections with different soil-binder combinations, three of which were based on alkaline activated cement. The mechanical properties of all segments were evaluated, on-site and in the laboratory, together with an environmental assessment and a preliminary financial anal- ysis. The results show that the alkaline cement-based materials have mechanical performances similar to traditional binders, with still some margin of optimization due to, their almost embryonic stage of development.