Stress-strain response of soft soils stabilised with alkali activated industrial by-products

Alternative binders based on the alkaline activation technology have been strongly investigated over the last decades as a potential replacement for Portland Cement. However, little research has been devoted to the shear behaviour of soft soils stabilised with those type of binders and their numerical modelling using constitutive models. This PhD thesis aims to deepen the knowledge in this area through the characterisation of the short- and long-term shear behaviour of soft soils stabilised with alkali-activated binders and the numerical modelling of the stress-strain behaviour of these geomaterials using a advanced constitutive model. In this context, triaxial tests were undertaken, after 28 and 90 curing days, in both a sandy lean clay and clay with high water content at reconstituted and stabilised states using alkali-activated blast furnace slags. The impact of the stress-history, represented by the overconsolidation ratio, and stress-state, represented by the initial mean effective stress, were investigated. Oedometer and isotropic consolidation tests were also undertaken. Scanning electron microscopy with energy dispersive spectroscopy, x-ray powder diffraction and leachate analyses were carried out to investigate the nature of the binding phases formed and the risk of contamination of soils. The results were used to calibrate an advanced kinematic hardening constitutive model proposed by Rouainia and Muir Wood, 2000 for natural clays. It was the first attempt of using this constitutive model in artificially cemented soils. Additionally, the opportunity to be integrated within a research project related to the application of alkali-activated industrial wastes in situ allowed me to be deeply involved in constructing a full-scale prototype of a (sub)base layer stabilised with alkali-activated binders and conventional binders. Big challenges arose, including the definition of a construction methodology, equipment selection, on-site handling of distinct materials, quality control techniques, among others. The in situ performance of the stabilised geomaterials was assessed through falling weight deflectometer tests, plate load field tests and unconfined compressive strength tests after 36 and 90 days. For each layer, it was estimated the financial cost of the construction and the equivalent CO2 emissions. The work showed the feasibility of the on-site application of alkali-activated binders in the stabilisation of soil layers in the context of transport infrastructures.

Name thesis:degree_name

Tese de doutoramento em Engenharia Civil

Grantor

Universidade do Minho

Year dc:date.issued

2021

Author dc:creator

• Silva, Manuela Corrêa Alves

Advisors dc:contributor.advisor

• Miranda, Tiago F. S.
• Cristelo, Nuno
• Rouainia, Mohamed

• Triaxial tests
• Kinematic hardening model
• SEM-EDS
• XRD
• Full-scale prototype
• Ensaios triaxiais
• Modelo de endurecimento cinemático
• Protótipo à escala real

Statement dc:rights

• openAccess

Licence dc:rights.uri

• http://creativecommons.org/licenses/by-nc-nd/4.0/

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1822/75516

OAI record oai:identifier

http://repositorium.sdum.uminho.pt/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Arepositorium.uminho.pt%3A1822%2F75516