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Title: Solid-liquid distribution of selected concrete admixtures in hardened cement pastes

Abstract

The distribution between hardened cement paste and cement pore water of selected concrete admixtures (BZMs), i.e., sulfonated naphthalene-formaldehyde condensate (NS), lignosulfonate (LS) and a gluconate-containing plasticiser used at the Paul Scherrer Institute for waste conditioning, was measured. Sorption data were fitted to a single-site Langmuir isotherm with affinity constants K = (19 {+-} 4) dm{sup 3} g{sup -1} for NS, K = (2.1 {+-} 0.6) dm{sup 3} g{sup -1} for LS and sorption capacities q = (81 {+-} 16) g kg{sup -1} for NS, q = (43 {+-} 8) g kg{sup -1} for LS. In the case of gluconate, a two-site Langmuir sorption model was necessary to fit the data satisfactorily. Sorption parameters for gluconate were K {sub 1} = (2 {+-} 1) x 10{sup 6} dm{sup 3} mol{sup -1} and q {sub 1} = (0.04 {+-} 0.02) mol kg{sup -1} for the stronger binding site and K {sub 2} = (2.6 {+-} 1.1) x 10{sup 3} dm{sup 3} mol{sup -1} and q {sub 2} = (0.7 {+-} 0.3) mol kg{sup -1} for the weaker binding site. Desorption of these BZMs from cement pastes and pore water in cement specimens prepared in the presence of the BZMs were then usedmore » to test the model. It was found that only minor parts of NS and LS could be mobilised as long as the cement composition was intact, whereas the sorption of gluconate was found to be reversible. The Langmuir model makes valuable predictions in the qualitative sense in that the pore water concentration of the BZMs is reduced by several orders of magnitude as compared to the initial concentrations. In view of the necessity for conservative predictions used in the safety analysis for disposal of radioactive waste, however, the predictions are unsatisfactory in that the measured pore water concentrations of NS and LS were considerably larger than the predicted values. This conclusion does not apply for gluconate, because its concentration in cement pore water was below the detection limit of {approx}50 nM.« less

Authors:
 [1];  [1];  [1]
  1. Laboratory for Waste Management, OHLD/002, Paul Scherrer Institut, CH-5232 Villigen (Switzerland)
Publication Date:
OSTI Identifier:
20877588
Resource Type:
Journal Article
Journal Name:
Waste Management
Additional Journal Information:
Journal Volume: 26; Journal Issue: 7; Conference: International workshop on mechanisms and modeling of waste/cement interactions, Meiringen (Switzerland), 8-12 May 2005; Other Information: DOI: 10.1016/j.wasman.2006.01.019; PII: S0956-053X(06)00050-X; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0956-053X
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CEMENTS; CONCRETES; CONDENSATES; DESORPTION; FORECASTING; FORMALDEHYDE; ISOTHERMS; NAPHTHALENE; RADIOACTIVE WASTES; SAFETY ANALYSIS; SENSITIVITY

Citation Formats

Glaus, Martin A, Laube, A, and Van Loon, Luc R. Solid-liquid distribution of selected concrete admixtures in hardened cement pastes. United States: N. p., 2006. Web. doi:10.1016/j.wasman.2006.01.019.
Glaus, Martin A, Laube, A, & Van Loon, Luc R. Solid-liquid distribution of selected concrete admixtures in hardened cement pastes. United States. https://doi.org/10.1016/j.wasman.2006.01.019
Glaus, Martin A, Laube, A, and Van Loon, Luc R. 2006. "Solid-liquid distribution of selected concrete admixtures in hardened cement pastes". United States. https://doi.org/10.1016/j.wasman.2006.01.019.
@article{osti_20877588,
title = {Solid-liquid distribution of selected concrete admixtures in hardened cement pastes},
author = {Glaus, Martin A and Laube, A and Van Loon, Luc R},
abstractNote = {The distribution between hardened cement paste and cement pore water of selected concrete admixtures (BZMs), i.e., sulfonated naphthalene-formaldehyde condensate (NS), lignosulfonate (LS) and a gluconate-containing plasticiser used at the Paul Scherrer Institute for waste conditioning, was measured. Sorption data were fitted to a single-site Langmuir isotherm with affinity constants K = (19 {+-} 4) dm{sup 3} g{sup -1} for NS, K = (2.1 {+-} 0.6) dm{sup 3} g{sup -1} for LS and sorption capacities q = (81 {+-} 16) g kg{sup -1} for NS, q = (43 {+-} 8) g kg{sup -1} for LS. In the case of gluconate, a two-site Langmuir sorption model was necessary to fit the data satisfactorily. Sorption parameters for gluconate were K {sub 1} = (2 {+-} 1) x 10{sup 6} dm{sup 3} mol{sup -1} and q {sub 1} = (0.04 {+-} 0.02) mol kg{sup -1} for the stronger binding site and K {sub 2} = (2.6 {+-} 1.1) x 10{sup 3} dm{sup 3} mol{sup -1} and q {sub 2} = (0.7 {+-} 0.3) mol kg{sup -1} for the weaker binding site. Desorption of these BZMs from cement pastes and pore water in cement specimens prepared in the presence of the BZMs were then used to test the model. It was found that only minor parts of NS and LS could be mobilised as long as the cement composition was intact, whereas the sorption of gluconate was found to be reversible. The Langmuir model makes valuable predictions in the qualitative sense in that the pore water concentration of the BZMs is reduced by several orders of magnitude as compared to the initial concentrations. In view of the necessity for conservative predictions used in the safety analysis for disposal of radioactive waste, however, the predictions are unsatisfactory in that the measured pore water concentrations of NS and LS were considerably larger than the predicted values. This conclusion does not apply for gluconate, because its concentration in cement pore water was below the detection limit of {approx}50 nM.},
doi = {10.1016/j.wasman.2006.01.019},
url = {https://www.osti.gov/biblio/20877588}, journal = {Waste Management},
issn = {0956-053X},
number = 7,
volume = 26,
place = {United States},
year = {Sat Jul 01 00:00:00 EDT 2006},
month = {Sat Jul 01 00:00:00 EDT 2006}
}