Geopolymer based on Calcined clay as untraditional stabilizer and its influence on swelling and shrinkage properties of expansive clayey soil

  • 24 Sep 2022
  • Published Resarch - Civil Engineering and Building Materials


Aref Alswidani,  Ibrahim Hammoud, and Ayman Meziab

Published in

Al Baath University Journal of Civil Engineering and Architecture, Volume 44, Issue 10, August 2022.



Recently, geopolymer (inorganic series material) emerge as substantial material of Portland cement, through convert natural or by-product materials such as furnace slug, fly ash, silica fume, as a resource of aluminosilicates to materials possess bonding properties, by using alkaline activators. This research try to acquire inorganic series based on natural materials as a resource of aluminosilicates in its amorphous phase, for this purpose, calcined clay was chosen as a precursor of this series. When we say calcined clay, we mean clay that thermally treated at high temperatures but less than fusion limit. Geopolymer based on calcined clay as a resource of amorphous aluminosilicates, was produced by adding an alkaline solution consists of sodium hydroxide and sodium silicate to calcined clay with thermally treatment. And the geopolymer was prepared in the laboratory, the ratio between alkaline activator (Na2SiO3+NaOH) to proposed soil stabilizer was equals to (0.85). the ratios of stabilizer to soil were (5,10,15%) as a percent of dry weight , and the moisture content in which the geopolymer added to soil was closed to liquid limit (LL) of mother soil and precisely (LL-5%). While the alkaline activator from Na2SiO3 and NaOH was prepared in the ratio Na2SiO3 / NaOH = 2.5. The results of experiments on samples of clayey soil stabilized by geopolymer, showed an extremely enhancement in the properties of linear shrinkage, and the value of linear shrinkage was cessed to zero when geopolymer was added at the ratio 15% to expansive clayey soil, while the linear shrinkage was restricted to lower levels when geopolymer was added at 10% and 5% respectively. In a similar manner, the values of relative swelling and swelling pressure reduced to zero value when the ratio of 15% of geopolymer was added to the expansive soil, while this restriction was less at ratios of 10% and 5% respectively. That is a clear indicator to the high efficiency of adding the geopolymer based on calcined clay, on restriction the phenomena of swelling and shrinkage of expansive clayey soil.

Keywords: Expansive clayey soil, geopolymer, alkaline activator, calcined clay, linear shrinkage, free swelling, pressure of swelling.

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