2026-05-30T00:12:59Zhttps://riuma.uma.es/rest/oai/request

oai:riuma.uma.es:10630/136292026-02-03T11:10:25Zcom_10630_2254col_10630_37953

Chemistry and Mass Density of Aluminum Hydroxide Gel in Eco-Cements by Ptychographic X-ray Computed Tomography Cuesta-García, Ana María Gómez-de-la-Torre, María de los Ángeles Santacruz-Cruz, María Isabel Trtik, Pavel Da Silva, Julio C. Díaz, Ana Holler, Mirko García-Aranda, Miguel Ángel Cemento Eco-cements are a desirable alternative to ordinary Portland cements because of their lower CO2 footprints. Some ye’elimite-based ecocements are attracting a lot of interest. Understanding the reasons for the mechanical performances requires the characterization of features such as mass density of the hydrated component phases, including the amorphous gel, on the submicrometer scale, which is challenging. Here we use ptychographic Xray computed tomography to provide 3D mass density and attenuation coefficient distributions of eco-cement pastes with an isotropic resolution close to 100 nm allowing to distinguish between component phases with very similar contrast. In combination with laboratory techniques such as the Rietveld method, 27Al MAS NMR, and electron microscopies, we report compositions and densities of key components. The ettringite and gel volume distributions have been mapped out in the segmented tomograms. Moreover, we discriminate between an aluminum hydroxide gel and calcium aluminum monosulfate, which have close electron density values. Specifically, the composition and mass density of two aluminum hydroxide gel agglomerates have been determined: (CaO)0.04Al(OH)3·2.3H2O with 1.48(3) g·cm−3 and (CaO)0.12Al(OH)3 with 2.05(3) g·cm−3, which was a long-standing challenge. 2017 journal article J. Phys. Chem. C 2017, 121, 3044−3054 1932-7455 http://hdl.handle.net/10630/13629 eng open access by-nc-nd ACS