Lightweight Cemented Soils: Mix Design, Production and Control

Development and validation of new technological methods for soil improvement in earthwork, allowing the reuse of excavated soils, are fundamental challenges in the framework of a sustainable geotechnical engineering design. Employment of natural soils not suitable for construction purposes to produce lightweight cemented soils represents an increasingly innovative technology. Lightweight cemented soils, obtained by adding air foam to soil-cement-water mixture to have a low density and self-levelling fresh mixture, are advantageously used for different earthworks, such as cavities filling, trench backfilling, embankment construction. The reuse of soil onsite, whose disposal normally significantly affects the overall construction costs, represents a clear environmental and economic advantage. In this paper a study on mix design for lightweight cemented soils is presented, highlighting the main effects of foam addition on physical and mechanical properties on different raw soils, based on experimental evidences. With reference to a case study (filling of an anthropic cavity in Piano di Sorrento, Italy), the effects of placement on lightweight cemented soils initial state are also addressed. A comparison in terms of physical and mechanical properties between material made in laboratory and sampled on site from the filling is shown. Furthermore, the role of construction controls and environmental conditions during placement on the relevant material parameters is highlighted.