The effect of artificial carbonate silt particles on the compressibility and crushing of calcareous clay

ABSTRACT: The South of México has a high probability of investing in offshore wind turbines in the next few decades. Mexican offshore industry experience in the Gulf of México generally relates to the extraction of oil and gas in shallow water sites with little or no calcareous clay sediments. However, most sites of interest with high offshore wind energy densities tend to be further south and in deeper water, with marine sediments with lower clay and higher carbonate silt contents. To properly develop these offshore wind sites, more knowledge of the static and dynamic behavior of high plasticity clay/carbonate silt sediments is required. This issue is further complicated by the expense of offshore sampling and testing, which makes testing of artificial analog soils attractive. This paper describes research involving the creation of artificial carbonate particles and their influence on the compression behavior of a high plasticity clay. The Atterberg limits of the artificial sediment (formed from a combination of Ottawa clay and calcite) developed in this project exhibited values in the range of calcareous clays reported for offshore sediments from Mexico and the US Gulf Coast. The artificial calcite particles reduced the liquid limit of the Ottawa clay material, but the plastic limits remained in the range of offshore calcareous clays. Moreover, the compressibility indices obtained for the intact clay, remolded clay and mixed samples were in the range of crushable soils when the samples were tested over a range of stresses. Based on these preliminary results, it seems to be possible to create artificial calcareous clay with behavior similar to offshore calcareous clays, which will potentially reduce the expense of preliminary offshore designs.