Characterization of soil treated with alkali-activated cement in large-scale specimens

Abstract

Soil improvement with hydraulic binders is currently used in practice because of the advantages of using the local soil enhancing its geotechnical properties. However, environmental issues related to quicklime applications and carbon-dioxide emissions associated to Portland cement production encouraged the development of new binders. In this work, alkaline-activated cement (AAC) synthetized by fly ash and an alkaline solution was used to stabilize silty sand. The behavior of the treated soil was evaluated performing tests on a physical model and the results were compared to laboratory data to define its compaction, strength, and stiffness properties. Those tests include nuclear density gauge measurements, light falling weight deflectometer tests, and plate load tests, whereas unconfined compression tests with unload–reload cycles and seismic wave measurements were performed at the laboratory. These tests, very common in current geotechnical practice, have proved to be also adequate to quality control and to evaluate the geomechanical properties of this material. The results at 28 days show a significant improvement given by the AAC, but still show some sensitivity to water when flooded. The comparison of results from different tests provided the evolution of stiffness with strain level.