The Efficiency of Alkaline Activator in Stabilizing Contaminated Soil using Metakaolin

Abstract

The main aim of the current study is to examine the effect of Al-kaline Activator on the efficiency of stabilization of contaminated soil using metakaolin –based geopolymer and comparable it with samples stabilized with non-activator metakaolin. To implement that, artificial contaminated soil was prepared by mixing the selected site soil with (2000 and 1500)ppm of lead and nickel respectively. Then ,rich silicon materials such as metakaolin use as an alternative cementations materials. . Different percentages of Metakaolin which are (4%,6%,8%,10% and 12 %) mixed with activator  with 10 molar of NaOH concentrations along with 5 molar Na2SiO3 solution for different curing time (7day,14day and 28 day). Unconfined Compressive Strength UCS, The Field Emission Scanning Electron Microscope (FESEM), and X-Ray Diffraction XRD are conducted for untreated and treated soil to illustrate the effect of al-kaline activator with MK on stabilized contaminated soil. The results show that the optimum value of strength was  5.614 Mpa by addition of 10% MK with activator for curing 7 days, while the value of strength is 0.159Mpa by addition 10 % MK without activator for curing 7 days. These results are the highest value of UCS for all curing time and for two group(Met.+ Act and MK only).  The micro-structural characterization of the samples stabilized by metakaolin –based geopolymer and samples stabilized by non-activator metakaolin are presented in this research. The different  in the mineralogy and morphology structure due to the effect of stabilizer of metakaolin with activator and metakaolin without activator were discussed based on X-ray Diffractometry (XRD), and Field Emission Scanning Electron Microscopy (FESEM). XRD pattern of treated soil shows the intensity of the peaks achieved with calcite and quartz and increased proportions of calcite (CaCO3) which is an indication of the presence of  cement compounds for samples  of metakaolin –based geopolymer and does not appear in the samples of non-activator metakaolin. While the morphology results of FESEM show the clay particles covered by cementations compounds due to the reaction of the Geopolymer with clay minerals which led to the production of binder particles and the formation of geopolymer gels which are confirmed for metakaolin  group with activator.