Effect of Adding Calcined Clay and Lime on the Strength Properties Clayey Soil
Dr. Ibraheem Hamood, Dr. Aref al-Swaidani, Eng. Ayman Meziab
Tishreen University Journal for Research and Scientific Studies - Engineering Sciences Series Vol. (14) No. (4) 9142
Calcined clay was obtained by thermal treatment of the clayey soil used in this study, with three levels of temperature ranges from (450, 650, 850°C) for 3hours in a laboratory furnace. Pozzolanic activities of treated soil samples, were determined using Chapelle test modified at each level, and the third level(850°C/3hours) was chosen as it was the best result of Chapelle test. To emphasis the pozzolanic activity, another test was carried out by using cubic specimens (4x4x4cm) in compressive strength measurements of mortars containing calcined clay, lime and standard sand, the results showed appreciable development in strength with the increase of temperature range and curing time of specimens. Combinations of clayey soil, lime and calcined clay according to the best result obtained from Chapelle test, were prepared, lime was added by constant percentage (6%) of dry weight of soil in all combinations, while the calcined clay ranged from (0%) to (20%). The testes that carried out on each combination were: compression test in standard proctor mould, Atterberg limits, Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR). The optimum moisture content and maximum dry density were obtained, and the results showed improvement in consistency properties with the decrease in plasticity index by the increase of percentages of calcined clay added to the clayey soil stabilized by lime, unconfined compressive strength increased from (315 KPa) to (569 KPa), the most obviously parameter increasing was (CBR) which increased from (2.89%) to(79.41%), all of that at the combination 6% lime, 20% calcined clay. that was a clear indicator to the improvement that took place in the clayey soil strength properties, when treated with calcined clay and lime.
Key words: Calcined clay, lime, plasticity index, compaction properties, Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR).