Synthetic glass with high alkali-reactivity and near-zero RM- CO2 emissions

As cement-related CO2 emissions increase, alternatives are actively sought. Cement substitution by slag and fly ash is standard practice worldwide and while higher side stream utilization is necessary, their volumes are not adequate to significantly alter global CO2 emissions. Cement substitution by, and alkali activation of, calcined clays offer an alternative with zero raw-material-related CO2 (RM-CO2) emissions. Please click Additional Files below to see the full abstract

Alkali-activated mineral wools

Mineral wools –a general term for stone wool and glass wool– are the most common building insulation materials in the world. The amount of mineral wool waste generated in Europe totaled 2.3 Mt in 2010 – including wastes from mineral wool production and from construction and demolition industry. Unfortunately, mineral wools are often unrecyclable due to their fibrous nature (Figure 1) and low density. Thus, the utilization of mineral wool waste in post-consumer products remains low. Please click Additional Files below to see the full abstract

Magnetically uniform and tunable Janus particles

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98670/1/ApplPhysLett_98_024101.pd

Exploring Mechanisms of Hydration and Carbonation of MgO and Mg(OH)2 in Reactive Magnesium Oxide-based Cements

Reactive magnesium oxide (MgO)-based cement (RMC) can play a key role in carbon capture processes. However, knowledge on the driving forces that control the degree of carbonation and hydration and rate of reactions in this system remains limited. In this work, density functional theory-based simulations are used to investigate the physical nature of the reactions taking place during the fabrication of RMCs under ambient conditions. Parametric indicators such as adsorption energies, charge transfer, electron localization function, adsorption/dissociation energy barriers and the mechanisms of interaction of H2O and CO2 molecules with MgO and brucite (Mg(OH)2) clusters are considered. The following hydration and carbonation interactions relevant to RMCs are evaluated i) carbonation of MgO, ii) hydration of MgO, carbonation of hydrated MgO, iii) carbonation of Mg(OH)2, iv) hydration of Mg(OH)2 and v) hydration of carbonated Mg(OH)2. A comparison of the energy barriers and reaction pathways of these mechanisms shows that the carbonation of MgO is hindered by presence of H2O molecules, while the carbonation of Mg(OH)2 is hindered by the formation of initial carbonate and hydrate layers as well as presence of excessed H2O molecules. To compare these finding to bulk mineral surfaces, the interactions of the CO2 and H2O molecules with the MgO(001) and Mg(OH)2 (001) surfaces are studied. Therefore, this work presents deep insights into the physical nature of the reactions and the mechanisms involved in hydrated magnesium carbonates production that can be beneficial for its development

Characterization of an aged alkali-activated slag roof tile after 30 years of exposure to Northern Scandinavian weather

Alkali-activated materials (AAMs) have been known as an alternative cementitious binder in construction for more than 120 years. Several buildings utilizing AAMs were realized in Europe in the 1950s–1980s. During the last 30 years, the interest towards AAMs has been reinvigorated due to the potentially lower CO2 footprint in comparison to Portland cement. However, one often-raised issue with AAMs is the lack of long-term studies concerning durability in realistic conditions. In the present study, we examined a roof tile, which was prepared from alkali-activated blast furnace slag mortar and exposed to harsh Northern Scandinavian weather conditions in Turku, Finland, for approximately 30 years. Characterization of this roof tile provides unique and crucial information about the changes occurring during AAM lifetime. The results obtained with a suite of analytical techniques indicate that the roof tile had maintained excellent durability properties with little sign of structural disintegration in real-life living lab conditions, and thus provide in part assurance that AAM-based binders can be safely adopted in harsh climates. The phase assemblage and nanostructural characterization results reported here further elucidate the long-term changes occurring in AAMs and provide reference points for accelerated durability tests and thermodynamic modelling

Asynchronous Magnetic Bead Rotation (AMBR) for Biosensors.

As antibiotic resistance of pathogenic bacteria is now a declared global threat, dubbed by the US Centers for Disease Control (CDC) as one of the most pressing public health problems worldwide, faster, growth-based methods are needed to be able to treat infections more effectively. Here we present the latest developments in the Asynchronous Magnetic Bead Rotation (AMBR) biosensor toward this goal. Asynchronous rotation of a magnetic bead in a fluid occurs when a rotating magnetic field exceeds a critical driving frequency. The frequency of the asynchronously rotating magnetic bead is a linear function of its volume, as well as of the fluid’s viscosity, and can therefore be used as a volumetric sensor. These sensors, called here Asynchronous Magnetic Bead Rotation (AMBR) sensors, were first used for bio-applications in 2007. This dissertation shows the development of various aspects of the AMBR biosensor: (1) the effect of the sensor’s frequency on its sensitivity of detection is investigated, (2) an AMBR sensor is optimized for measuring the growth of individual bacterial (E. coli) cells, achieving an 80 nm sensitivity to the cell length, (3) an off-the-microscope method for the observation of AMBR sensor signals is demonstrated, and (4) self-assembled AMBR sensors are developed for potentially rapid and scalable antibiotic susceptibility testing of bacteria. AMBR offers a simple and robust method for translating nanoscale volumetric changes into easily measurable frequency changes. It is a platform technology applicable to a multitude of high resolution volumetric and viscosity measurements, one of the primary applications being in healthcare: bacterial growth can be measured even on the single cell level. Due to AMBR biosensors high sensitivity, the bacterial resistance to antimicrobials can be rapidly determined. The resistance was determined within one hour for a clinical E. coli isolate, potentially leading to faster information on what would be the appropriate therapy for the specific case/patient.Ph.D.Applied PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/86488/1/pkkinn_1.pd

Utilization of Mineral Wools as Alkali-Activated Material Precursor

Mineral wools are the most common insulation materials in buildings worldwide. However, mineral wool waste is often considered unrecyclable because of its fibrous nature and low density. In this paper, rock wool (RW) and glass wool (GW) were studied as alkali-activated material precursors without any additional co-binders. Both mineral wools were pulverized by a vibratory disc mill in order to remove the fibrous nature of the material. The pulverized mineral wools were then alkali-activated with a sodium aluminate solution. Compressive strengths of up to 30.0 MPa and 48.7 MPa were measured for RW and GW, respectively, with high flexural strengths measured for both (20.1 MPa for RW and 13.2 MPa for GW). The resulting alkali-activated matrix was a composite-type in which partly-dissolved fibers were dispersed. In addition to the amorphous material, sodium aluminate silicate hydroxide hydrate and magnesium aluminum hydroxide carbonate phases were identified in the alkali-activated RW samples. The only crystalline phase in the GW samples was sodium aluminum silicate. The results of this study show that mineral wool is a very promising raw material for alkali activation