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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Adsorption Studies of S Labelled Superplasticizer in Cement-Based Grout
Author(s): M. N. Onofrei and M. N. Gray
Publication: Special Publication
Appears on pages(s): 645-660
Keywords: adsorption; cements; C3A; C3S; electron microscopes; grout; leaching; plasticizers; radiography; Materials Research
Abstract:Laboratory studies have been carried out to determine the leachability of the adsorbed superplasticizer (an Na-sulfonated naphthalene formaldehyde condensate) and its location within the structure of hardened cement tastes. The superplasticizer, labelled with 35 S, was incorporated in a reference cement-based grout (90 percent Type 50, 10 percent silica fume, 0.4 ó w/c ó 0.6). Static leaching tests were used to determine the release of labelled superplasticizer to solutions as a function of temperature, groundwater composition, and grout surface area to groundwater volume ratio. The quantity of 35 S in the leachate was determined using liquid scintillation counting. Electron-microautoradiography combined with scanning electron microscopy and energy dispersive x-ray spectroscopy were used to identify the cement phases containing the labelled superplasticizer. The results show that superplasticizer can be leached from grouts, but the cumulatively released quantities are very small (approximately 10(12 kg/mý). Most of the released superplasticizer appears to come from the capillary pore space of the hardened grout; however, some release may result from dissolution of the cement phases. Increasing temperature and/or grout surface area to groundwater volume ratio increases the release rate of superplasticizer. Analyses, using electron-microautoradiography and scanning electron microscopy, indicate that the majority of the adsorbed super plasticizer resides on the C-A-H phases and the calcium-rich phases of C-S-H in the cement.
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