Development of Alkali-activated Foamed Lightweight Mortar Tungsten Mining Waste Mud-based Incorporating Expanded Cork

In this study, an Alkali-activation of tungsten mining waste mud (TMWM) was combined with aluminium powder (Al) as a blowing agent (gas foaming method). The synthesis of inorganic alkali-activated foamed mortar (AA-FM) and alkali-activated lightweight foamed mortar (AALW-FM) was achieved by incorporating expanded granulated cork (EGC) and one type of river sand < 2 mm. Al powder was added first to the dry mix with the mass used varying from 0.1 g to 0.5 g. Precursors and activators were included to produce a homogeneous mixture, which was placed into a mould (100x100x60 mm3), and cured in the oven at 60° C for 24 hours. The influence of two main parameters (Al powder contents and cork particles) on the AA-FM and AALW-FM properties (compressive strength, density, expansion volume and pore size distribution) were investigated. The compressive strength of the foams in the case of highly porous structures of the AALW-FM and AA-FM achieved 4.1MPa and 13.2MPa respectively, for samples with a larger amount of Al powder (0.5g). Open celled hardened of the AALW-FM and AA-FM with 0.5g Al shows a high porosity of 40% and 81% respectively. Therefore, tungsten mining waste-based alkali-activated foams shows potential as a thermal insulation material in certain situations. Keywords: Tungsten mining waste, Alkali-activated, Foamed Material

Feasibility of alkali-activated mining waste foamed materials incorporating expanded granulated cork

Different combinations of mining waste mud, grounded waste glass, Portland cement, metakaolin and expanded cork were mixed together with alkaline activators (sodium silicate and sodium hydroxide solution) and as well aluminum powder or hydrogen peroxide to produce foamed lightweight materials. The size of the mineral materials is under 500 µm and expanded cork particles size is between 2 to 4 mm. The expanded cork added to the mixes changed between 10 to 40% volume of total solids. The influence of expanded cork on compressive strength was investigated. Precursors and activators were mixed together to produce a homogeneous mixture, which was placed into a cubic mold (40 x 40 x 40 mm3), and cured at a temperature of 60°C, for 24 hours. After curing process, samples without foaming agents achieved the maximum compressive strength of 14.7 and 19.5 MPa for 7 and 28 days respectively. The porosity was observed by the naked eye of large voids in a range of 4 mm in size. Microstructure analyses were carried on by SEM. Samples made with aluminum powder showed higher volume increase about 358% compared with samples made with hydrogen peroxide that presented a 141% volume increase. This preliminary study shows the feasibility to produce new improved lightweight foamed alkali activated materials incorporating expanded cork with potential applications in artistic, architectural, and historical heritage restoration

Air-sea turbulent fluxes from a wave-following paltform during six experiments at sea

Turbulent fluxes at the air‐sea interface are estimated with data collected in 2011 to 2017 with a low‐profile platform during six experiments in four regions. The observations were carried out with moderate winds (2–10 m/s) and averaged wave heights of 1.5 m. Most of the time, there was a swell, with an averaged wave age (the ratio between wave phase speed and wind speed) being equal to 2.8 ± 1.6. Three flux calculation methods are used, namely, the eddy covariance (EC), the inertial dissipation (ID), and the bulk methods. For the EC method, a spectral technique is proposed to correct wind data from platform motion. A mean bias affecting the friction velocity (u*) is then evaluated. The comparison between EC u* and ID u* estimates suggests that a constant imbalance term (ϕimb) equal to 0.4 is required in the ID method, possibly due to wave influence on our data. Overall, the confidence in the calculated u* estimates is found to be on the order of 10%. The values of the drag coefficient (CD) are in good agreement with the parameterizations of Smith (1988, https://doi.org/10.1029/JC093iC12p15467) in medium‐range winds and of Edson et al. (2013, https://doi.org/10.1175/JPO‐D‐12‐0173.1) in light winds. According to our data, the inverse wave age varies linearly with wind speed, as in Edson et al. (2013, https://doi.org/10.1175/JPO‐D‐12‐0173.1), but our estimates of the Charnock coefficient do not increase with wind speed, which is possibly related to sampling swell‐dominated seas. We find that the Stanton number is independent from wind speed