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Chemistry of cement hydration in polymer-modified pastes containing lead compounds

2005; Elsevier BV; Volume: 26; Issue: 4-5 Linguagem: Inglês

10.1016/j.jeurceramsoc.2005.07.036

1873-619X

Luca Zampori, Isabella Natali Sora, Renato Pelosato, Giovanni Dotelli, Paola Gallo Stampino,

Innovations in Concrete and Construction Materials

The role of polymeric additives on the hydration process of cement pastes admixed with a lead compound (Pb3O4) was investigated. Three series of pastes were prepared: the reference series, mixing water with Ordinary Portland Cement (OPC), and two series in which whether a styrene–butadiene rubber latex or a superplasticiser based on acrylic-modified polymer was added to the pastes. For each series, 5 and 10 wt% of Pb were mixed with the pastes. Phase analysis and microstructural characterisation were carried out by means of X-ray powder diffraction and SEM–EDX. Thermogravimetric analysis was performed to monitor the hydration degree of the three pastes; indeed, quantitative determination of portlandite and calcite was performed. Dynamic leach tests were performed on solidified monoliths to evaluate the effective immobilisation of Pb 3O4. After 384 h leaching, excellent results were obtained by pastes mixed with superplasticiser that showed a cumulative release of Pb equal to 0.62 mg/l for samples containing 5 wt% of Pb, and equal to 0.84 mg/l for samples bearing 10 wt% of Pb. © 2005 Elsevier Ltd. All rights reserved.