Effect of the soil type on the biocementation process by enzymatic way

Abstract

The effect of the enzymatic CaCO3 precipitation on the behaviour of four soils (from a poorly graded sand to a fine and organic soil) is studied in this work. The analysis is based on the results of UCS tests, where the results from the non-stabilised specimens are compared with specimens stabilised with a urease concentration of 8 kU/L and an equimolar solution of urea-CaCl2 of 0.5 mol/L. Additionally, pH and scanning electron microscopy (SEM) tests with energy dispersive X-ray (EDX) analyses are performed to analyse the microstructure and the local chemical composition. The results of the UCS tests show that, in the case of the sandy and silty soils, the process of enzymatic CaCO3 precipitation potentiates the strengthening of the soils while, in the organic soil, a detrimental effect is observed. The SEM tests show the existence of vestiges of calcium in the biostabilised soils studied.