Bio-cimentação em solos arenosos: efeito do tempo de tratamento na compressibilidade e na quantidade de bio-cimento produzido

Maria Carolina da Silva Damas Pinto

Key information

Authors:

Maria Carolina da Silva Damas Pinto (Maria Carolina Da Silva Damas Pinto)

Supervisors:

Maria Rafaela Pinheiro Cardoso (Rafaela Cardoso)

Published in

January 11, 2021

Abstract

Concrete is the second most-consumed product in construction after water. Its production causes more than 5% of anthropogenic CO2 emissions and therefore, due to the increasing awareness of the climate impact there is a large interest in reducing its carbon footprint. Microbial induced calcium carbonate precipitation (MICP) technique was introduced at the end of the 20th century as an alternative to the use of cement for soil improvement. MICP is a biologically driven calcium carbonate precipitation technology that uses urease producing bacteria fed with a calcium source. With this treatment the precipitation of calcium carbonate in the soil pores occurs, reducing soil permeability and increasing stiffness and strength as a function of the amount precipitated. The aim of this work was to understand how the treatments duration would influence the mechanical behaviour of the soil by analysing compressibility and the amount of bio cement produced, and indirectly, the durability of the technique. To fulfil this goal, the specimens were prepared with different types of treatment for later comparison and to understand how the presence of bio-cement affects the observed behaviour. The tests carried out were oedometer tests, leaching tests, the analysis of electron scanning microscope (SEM) images, the chemical characterization by spectroscopy X-ray diffraction and porosimetry by mercury intrusion (MIP). All the conclusions obtained justify the need for future investigations so that more cases of up-scaling from the laboratory to the field can be reproduced.