Cement Enhanced Short Columns for Stabilizing Plastic Clays under Structures

Introducing cement columns as a stabilizing approach under structures built on plastic clays may be a better option than traditional cement stabilization or grout injection. To transfer forces to a sufficiently deep depth, this study investigates the use of short columns of plastic clay enhanced with cement at various concentrations. The subsurface material was treated with 2, 4, and 8% cement by weight. The clay columns were cured for 28 and 90 days. The 90-day curing was conducted to allow full strength development, as the material includes clay. This study examines cement-enhanced clay columns in terms of essential geotechnical qualities such as compressibility and unconfined compressive strength, under varying curing conditions. The results of this study indicated to cement-treated columns can transfer loads as high as 25 to 405 t for a group of columns ranging from 9 to 49 with diameters of 0.3 m. Allowable loads for a 0.3 m diameter column varied from 186 kN to 624 kN for a cement content in the range of 2%–6%. Pozzolanic interactions between soil and cement were found to introduce sufficient strength to support superstructure loads exerted by residential buildings and light weight to moderate structures.