Resistance of blended cement pastes subjected to organic acids: Quantification of anhydrous and hydrated phases |
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| Affiliation: | 1. LMDC, Université de Toulouse, INSA, UPS, 135 Avenue de Rangueil, 31077 Toulouse Cedex 04, France;2. Laboratoire de Génie Chimique, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France;3. LISBP, Université de Toulouse, CNRS, INRA, INSA, 135 Avenue de Rangueil, 31077 Toulouse Cedex 04, France;1. Empa, Laboratory for Concrete & Construction Chemistry, CH-8600 Dübendorf, Switzerland;2. Paul Scherrer Institut, Laboratory for Waste Management, 5232 Villigen PSI, Switzerland;3. HTW Dresden University of Applied Sciences, Department of Civil Engineering, 01069 Dresden, Germany;4. Department of Materials Science and Engineering, University of California Los Angeles, Los Angeles, CA, USA;5. Lafarge Centre de Recherche, 38291 Saint-Quentin Fallavier, France;6. BASF Schweiz AG, 5082 Kaisten, Switzerland;7. University of Sheffield, Department of Materials Science and Engineering, Sheffield S1 3JD, UK;1. Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, Toulouse F-31077, France;2. INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, Toulouse F-31400, France;3. CNRS, UMR5504, Toulouse F-31400, France;4. Université de Toulouse, INSA, UPS, LMDC, 135 avenue de Rangueil, Toulouse 31077, France |
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| Abstract: | Concrete for agricultural construction is often subject to aggressive environmental conditions. Ground granulated blast furnace slag (GGBFS) or metakaolin (MK) largely improve the chemical resistance of the binder. Anhydrous particles seem particularly resistant to the acid solution. The purpose of this study is to quantify anhydrous particles in blended cement pastes as a function of acid exposition time in order to evaluate their acid resistance.Cement pastes were moist cured for 28 days and then immersed in an acetic acid solution for 2 months. The quantification of the anhydrous phases was carried out using 29Si MAS NMR, selective dissolution and back-scattered electron (BSE) images analysis, while the hydrated phases content was evaluated by TGA. After 28 days of hydration, 60% of OPC, 44% of GGBFS and 76% of MK particles were hydrated. The amount of anhydrous particles drops for all materials during acid immersion. After 2 months of immersion, the amount of anhydrous particles drops by 49%, 23% and 15% for OPC, GGBFS, and MK respectively. This study confirms that GGBFS and MK anhydrous and hydrates phases present higher acid resistance than OPC. |
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| Keywords: | Quantification Anhydrous phases Hydrates Organic acids NMR Selective dissolution Image analysis Thermogravimetry Granulated blast furnace slag Metakaolin |
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