Modeling of Machining Chips of Steel Parts for Their Recycling and Reinforcement of Cementitious Matrix

Bouzeroura, M.; Bouafia, Youcef; Moussaceb, Karim

doi:10.12816/0044606

Cited by 4 publications

(1 citation statement)

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“…Toxic waste can be immobilised in hardened cement stone by solidification/stabilization. (S/S) [1,6,15,[7][8][9][10][11][12][13][14]. Solidification describes the processes that transform waste into a waterproof solid with strong cohesion and with good physical and mechanical properties.…”

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Influence of a Chromium-rich Industrial Waste on the Hydration and Hardening Processes of Portland Cements with Slag and Limestone Additions

Oproiu¹,

Pârvan²,

Voicu³

et al. 2020

Rev. Chim.

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This research work assesses the influence of a chromium-rich waste (from potassium dichromate manufacture) on the hydration and hardening processes of two types of Portland cements with limestone filler and slag additions. Therefore, mixtures of Portland cement and chromium-rich waste, corresponding to 0.5% wt. and 1% wt. Cr, were prepared and tested. The analyses performed on cement pastes with chromium waste content, showed that chromium immobilization is mainly due to the formation of Ca6Al2Cr3O18�32H2O (CrEt); this compound results by the substitution of [SO4]2- groups from ettringite lattice of with [CrO4]2-. CrEt crystals growth on the surface of clinker particles forms a diffusion barrier which explains longer setting times for cements with chromium content. The increase of chromium content in the studied systems decreases the compressive strength values but these remain above the lower limits imposed for this type of materials. The chromium content in leachates prepared according to the method described in SR EN 12457-2, was well below the legal limit of 70 mg/Kg established by Romanian legislation. A better chromium immobilisation was achieved in the cement with slag content, in good correlation with the nature and amount of formed hydrates.

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