A new method for increasing the density of modulated sandy soils by using cement dust

This research is an empirical method for estimating the possibility of using cement dust as an additive for sandy soil during the field compaction process. The soil samples were brought from Al-Najaf city and treated with cement dust .Twenty test models were prepared and compacted in the standard and modified mould of Proctor test. These models were divided into two broad series, firstly consisted of ten soil samples, five from these samples were carried out at constant compactive energy (E=355.5 kJ/m3) for cement dust (4 , 8, 12 and 16%) in addition to one case with no cement dust. This energy is less than standard Proctor test energy. Another retained models were tested with compactive energy equal to the energy of standard Proctor test (E=592.5 kJ/m3) for the same percentage cement dust. The second series of models were involved ten models, five samples compacted at energy corresponding to Modified Proctor Test (E=1197.03 kJ/m3) and other retained models at compactive energy higher than compactive energy of the modified Proctor test (E=2681.4 kJ/m3). The results of laboratory tests which carried out on selected soil showed with increasing compactive energy, the optimum cement dust decreased (this percent was corresponding to the peak dry density in the laboratory) . In other words, the optimum cement dust percents were equal to (4%), (6.6%), (8%) and (12%) for compactive energy (E=355.5, 592.5, 1197.03 and 2681.4 kJ/m3) respectively, and the addition of these percents of cement dust leaded to increase in the maximum dry density (4%, 5.3%, 17.1% and 20.5%) for compactive energy (E=355.5, 592.5, 1197.03 and 2681.4 kJ/m3) respectively.