Global climate change related to anthropogenic CO₂ emissions is one of the most significant challenges for the future of human life on Earth. There are many potential options for reducing or even eliminating atmospheric CO₂ emissions including underground sequestration, carbon mineralization and ocean storage. One of the most promising materials for carbon mineralization is Mg(OH)₂ which is highly reactive and capable of forming stable carbonates. Here we show a novel low-carbon method of producing Mg(OH)₂, from globally abundant olivine-rich silicate rocks. A combination of acid digestion and electrolysis of olivine were used to produce Mg(OH)₂ in a fully recoverable system. The use of Mg(OH)₂ from olivine provides a viable pathway for significant industrial scale reductions in global anthropogenic greenhouse gas emissions.

Perchlorate (ClO₄⁻) is globally enriched in Martian regolith at levels commonly toxic to plants. Consequently, perchlorate in Martian regolith presents an obstacle to developing agriculture on Mars. Here, we assess the effect of perchlorate at different concentrations on plant growth and germination, as well as metal release in a simulated Gusev Crater regolith and generic potting soil. The presence of perchlorate was uniformly detrimental to plant growth regardless of growing medium. Plants in potting soil were able to germinate in 1 wt.% perchlorate; however, these plants showed restricted growth and decreased leaf area and biomass. Some plants were able to germinate in regolith simulant without perchlorate; however, they showed reduced growth. In Martian regolith simulant, the presence of perchlorate prevented germination across all plant treatments. Soil column flow-through experiments of perchlorate-containing Martian regolith simulant and potting soil were unable to completely remove perchlorate despite its high solubility. Additionally, perchlorate present in the simulant increased metal/phosphorous release, which may also affect plant growth and biochemistry. Our results support that perchlorate may modify metal availability to such an extent that, even with the successful removal of perchlorate, Martian regolith may continue to be toxic to plant life. Overall, our study demonstrates that the presence of perchlorate in Martian regolith provides a significant challenge in its use as an agricultural substrate and that further steps, such as restricted metal availability and nutrient enrichment, are necessary to make it a viable growing substrate.

Postyield steel–concrete bond has been the subject of considerable investigations using pull-out or direct tensile tests; however, the degradation in bond due to reinforcement yielding in RC beams subjected to lateral loading has not been fully scrutinized. Conventional measuring instruments (strain gauges or LVDTs) cannot precisely measure strain distribution along the yielded reinforcing bar with a minimum level of interference to the bond. Therefore, this study reports the postyield behavior of bond in RC cantilever beams subjected to monotonic lateral loading monitored using a distributed fiber-optic strain sensing system (DFOSSS). The DFOSSS enabled accurate monitoring of deformations of the embedded reinforcing bars and the strains on the concrete surface. This allowed slip, steel stress, bond stress, bond deterioration length, and the locations of cracks to be determined. Using the new values for maximum bond stress, a model was proposed to predict pre- and postyield bond behavior, including steel strain effect. Finally, the mean bond stress values were presented for the simple assessment of bond strength in both pre- and postyield regions.

The transport characteristics of waste glass powder incorporated self-compacting concrete (SCC) for a number of different durability indicators are reported in this paper. SCC mixes were cast at a water to binder ratio of 0.4 using glass powders with a mean particle size of 10, 20 and 40 µm and at cement replacement levels of 20, 30 and 40%. The oxygen permeability, electrical resistivity, porosity and chloride diffusivity were measured at different ages from 3 to 545 days of curing. The amount and particle size of the incorporated waste glass powder was found to influence the durability properties of SCC. The glass incorporated SCC mixes showed similar or better durability characteristics compared to general purpose (GP) and fly ash mixes at similar cement replacement level. A significant improvement in the transport properties of the glass SCC mixes was observed beyond 90 days.