Raissa Douglas Ferron

Use of biomineralisation in developing smart concrete inspired by nature

Recently, interest has focused on leveraging the biological functions of microorganisms to develop smart cement-based materials. This paper provides an overview of the calcium carbonate biomineralisation process in nature and presents a review of the work conducted by various groups around the world on biogenic calcium carbonate formation as it relates to the hydration, microstructure, properties, and performance of cement-based materials. Promises and concerns of applying biomineralisation in cement-based materials are also discussed, and directions for future research are explored.

The Fresh State: From Macroscale to Microscale to Nanoscale

There is a need to increase fundamental knowledge about the rheological behavior of cement-based materials. Cementitious fluids have complex rheologies and typically exhibit shear-thinning viscosity, yield stress, elasticity, and thixotropy; this complex rheological behavior results from the heterogeneity of the material and the finite time that it takes for the in situ structure to rearrange when it is subjected to shear-induced stresses. The specific cause of the rearrangement depends on interactions at the molecular level, which, unfortunately, are poorly understood. The rheological behavior of cement-based materials is directly linked to the aggregation, deaggregation, reaggregation, and dispersion of the solid particles. Research that can provide information about any of these phenomena would advance the state of knowledge of the flow behavior of cement-based materials. This paper presents an approach to characterization of the fresh-state structure of cement paste suspensions. It is shown that this method can be used to investigate the flocculation and floc properties of cement pastes.

Monitoring the self-healing process of biomimetic mortar using coda wave interferometry method

Internal stresses might induce microscopic cracks in concrete, which can provide pathways for ingress of harmful chemicals and can lead to loss of strength. Recent research in concrete materials suggests that it might be possible to develop a smart cement-based material that is capable of self-healing by leveraging the metabolic activity of microorganisms to provide biomineralization. Limited research on biomineralization in cement-based systems has shown promising results that healing of cracks can occur on the surface of concrete and reduce permeability. This paper presents the results from an investigation regarding the potential for a cement-based material to repair itself internally through biomineralization. Compressive strength test and coda wave interferometry (CWI) analyses were conducted on mortar samples that were loaded to 70% of their compressive strength and cured in different conditions. Experimental results indicate that the damaged mortar samples with microorganisms showed significantly h...

Real time control of fresh cement paste stiffening: Smart cement-based materials via a magnetorheological approach

A smart cement-based magnetorheological (MR) fluid, one that could be tailor-designed to yield the desired rheological properties of cement paste, in real time is presented. By incorporating magnetic particles inside the cement paste and by varying the magnitude of the magnetic field strength, the rheological response of the sample is altered significantly. This cement-based MR fluid would allow for better control over stiffening/setting behavior of concrete and can be useful in applications in which controlling the fresh-state behavior of concrete is critical. In this work, magnetic fields were altered in a low-high-low and high-low-high pattern to assess the effect of cyclic variations of the magnetic field on the rheological behavior. It was found that a cement-based MR fluid does exhibit field sensitivity in its rheological behavior when the magnetic field is varied. At early ages, when the magnetic field is varied, the rheological behavior was seen to be less dependent on the time frame at which the magnetic field is applied and more related to the magnitude of the magnetic field. At later ages, in the presence of a cyclic magnetic field, the rheological response will be influenced by the magnetorheological response and by aging mechanisms (e.g., hydration and thixotropy) that impact the stiffening of cement paste.