Cementitious materials with mineral additions: impact on the self-healing kinetics and the products formation
| Autor: | Olivier, K, Darquennes, A, BENBOUDJEMA, F, Gagné, R, Louis, G, Betrancourt, D |
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| Přispěvatelé: | OLIVIER, Kelly, Centre de recherche sur les infrastructures en béton de l'Université de Sherbrooke (CRIB-US), Centre de recherche sur les infrastructures en béton de l'Université de Sherbrooke, Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), École des Mines de Douai (Mines Douai EMD), Institut Mines-Télécom [Paris] (IMT), Duke University, North Carolina State University, the University of North Carolina - Chapel Hill, and North Carolina Central University |
| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | International Conference on Self-Healing Materials International Conference on Self-Healing Materials, Duke University, North Carolina State University, the University of North Carolina-Chapel Hill, and North Carolina Central University, Jun 2015, Durham, NC, United States |
| Popis: | International audience; Ground granulated blast-furnace slags (GGBFS), as a hydraulic binder, are widely used for many years in engineering concretes. The French standards allow substituting 50% of Portland cement by GGBFS. This approach leads to a decrease in the CO2 emissions produced during clinkerisation process. Portland cement substitution by GGBFS can also improve the workability, decreases the hydration heat and increases the long-term compressive strength. GGBFS can also significantly improve the resistance to sulfate attack. Concrete structures made with GGBFS cement can be cracked at early age due to restrained shrinkage. This cracking can reduce mechanical and transport properties, leading to an increased risk of aggressive agents’ penetration. Self-healing of cracks, already observed on building sites, could partially overcome these durability issues.To understand the effect of GGBFS on self-healing kinetics and the type of self-healing products, five hydraulic binders were studied: two Portland cement (French and Canadian), two GGBFS (French and Canadian) mixed with Portland cement (named GGBFS formulation hereafter) and a French blended cement (62% of slag) named CEMIII/A. Each material was characterized by XRF, XRD, PZD test, fineness Blaine test and TGA. At 7 and 28 days, French and Canadian mortar specimens were cracked respectively to obtain three crack sizes: 50, 100 and 150 µm. The cracked specimens were then stored at 23 °C and 100% R.H for up to 6 months. The evolution of self-healing is followed by X-ray tomography or air-flow measurements. SEM with EDS were performed on the sawed samples to identify and analyze self-healing products.Results show that two main products are formed: (1) calcite by the carbonation of portlandite in the matrix, and (2) supplementary reaction products (mainly C-S-H with various C/S ratios), formed by the reaction of anhydrous particles. Both GGBFS formulations show a good self-healing potential but the kinetics of the phenomenon are slightly different. Mortar made with French GGBFS presents the best self-healing potential compared to the four others formulations. Mortar with Canadian GGBFS presents a similar behavior as Canadian Portland cement. These results can be explained by the material characteristics but also by their hydration kinetics. A hydration model is currently developed in order to investigate more deeply these observations. |
| Databáze: | OpenAIRE |
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