Understanding the impact of climatic conditions on the long-term performances of soils stabilized with lime and cement is of crucial importance. Most of the available studies on durability solely rely on laboratory investigations to assess the effects of exposure to environmental-driven processes such as wetting and drying, leaching, etc. In this context, a research embankment built in 2010 with an expansive soil stabilized with 4% quicklime and a mix of 2% quicklime and 3% cement was sampled in 2021. A comprehensive experimental campaign was conducted using these samples to evaluate the performance of materials 11 years after the construction of the structure. The studies were completed by microstructural and physico-chemical investigations to understand the mechanisms that might explain changes in performance over time. The analysis of the hydro-mechanical properties of the soil sampled between the edge and the interior of the embankment was first performed. The results indicated that the material taken near the surface had a mechanical behavior equivalent to the untreated soil, demonstrating a total loss of the benefit brought by lime/cement addition. Towards the internal part of the embankment, the mechanical performance progressively increased. Physico-chemical investigations showed that on the edge of the backfill significant part of the calcium was leached 11 years after the construction. This was associated to a drop of pH, and to the formation of calcite. The microstructure was also significantly altered on the edge of the embankment compared to the internal part of the structure. Based on these results, a new mechanism of soil deterioration driven by climatic conditions was proposed. Water circulation and carbonation, associated to a significant reorganization of the microstructure were identified as the main phenomena responsible for the degradation of the treatment effects. This study showed that embankment slopes built with lime and cement stabilized expansive clay must be protected from weather-driven processes to limit any associated degradation.

Cement production in the world market is steadily increasing. In 2000, it was 1600 million tons, while as of 2013, the annual amount exceeded 4000 million tons. The burning of cement clinker is associated with the generation of waste. It is estimated that the amount of cement kiln dust (CKD), during combustion, reaches about 15-20%, which means 700 million tons per year. However, not all types of by-products are reusable due to high alkali, sulfate, and chloride contents, which can adversely affect the environment. One environmentally friendly solution may be to use CKD in the production of high-performance concrete (HPC), as a substitute for some of the cement. This paper presents a study of the short- and long-term physical and mechanical properties of HPC with 5%, 10%, 15%, and 20% CKD additives. The experiments determined density, water absorption, porosity, splitting tensile strength, compressive strength, modulus of elasticity, ultrasonic pulse velocity, and evaluated the microstructure of the concrete. The addition of CKD up to 10% caused an increase in the 28- and 730-day compressive strengths, while the values decreased slightly when CKD concentration increased to 20%. Splitting tensile strength decreased proportionally with 5-20% amounts of CKD regardless of HPC age. Porosity, absorbability, and ultrasonic pulse velocity decreased with increasing cement dust, while the bulk density increased for HPC with CKD. Microstructure analyses showed a decrease in the content of calcium silicate hydrate (C-S-H), acceleration of setting, and formation of wider microcracks with an increase in CKD. From the results, it was shown that a 15% percentage addition of CKD can effectively replace cement in the production of HPC and contribute to reducing the amount of by-product from the burning of cement clinker.