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Morandeau A.E.,Andlinger Center for Energy and the Environment | Morandeau A.E.,Ecole Superieure dIngenieurs des Travaux de la Construction de Caen | White C.E.,Andlinger Center for Energy and the Environment
Chemistry of Materials | Year: 2015

Oil well cements have received a significant amount of attention in recent years due to their use in high-risk conditions combined with their exposure to extremely aggressive environments. Adequate resistance to temperature, pressure, and carbonation is necessary to ensure the integrity of the well, with conventional cements prone to chemical degradation when exposed to CO2 molecules. Here, the local atomic structural changes occurring during the accelerated carbonation (100% CO2) of a sustainable cement, alkali-activated slag (AAS) have been investigated using in situ X-ray diffraction and pair distribution function analysis. The results reveal that the extent of carbonation-induced chemical degradation, which is governed by the removal of calcium from the calcium-alumino-silicate-hydrate (C-A-S-H) gel, can be reduced by tailoring the precursor chemistry; specifically the magnesium content. High-magnesium AAS pastes are seen to form stable magnesium-containing amorphous calcium carbonate phases, which prevents the removal of additional calcium from the C-A-S-H gel, thereby halting the progress of the carbonation reaction. On the other hand, lower-magnesium AAS pastes form amorphous calcium carbonate which is seen to quickly crystallize into calcite/vaterite, along with additional decalcification of the C-A-S-H gel. Hence, this behavior can be explained by considering (i) the solubility products of the various carbonate polymorphs and (ii) the stability of amorphous calcium/magnesium carbonate, where because of the higher solubility of amorphous calcium carbonate and associated saturation of solution with respect to calcium, additional C-A-S-H gel decalcification cannot proceed when this amorphous phase is present. These results may have important implications for the use of new cementitious materials in extremely aggressive conditions involving CO2 (e.g., enhanced oil recovery and geological storage of CO2), particularly because of the ability to optimize the durability of these materials by controlling the precursor (slag) chemistry. © 2015 American Chemical Society. Source


Benzerzour M.,Ecole Des Mines de Douai | Gagne R.,Universite de Sherbrooke | Abriak N.-E.,Ecole Des Mines de Douai | Sebaibi N.,Ecole Superieure dIngenieurs des Travaux de la Construction de Caen
Construction and Building Materials | Year: 2014

This paper presents an investigation on the origin and magnitude of the internal stresses at the interface between an overlay and an underlying reinforced-concrete slab subjected to cyclic flexural loading. Internal stresses were analyzed with finite-element modeling of two configurations of reinforced-concrete slab panels measuring 3.3 × 1.0 × 0.2 m: an intact reference slab and a repaired slab with a 40-mm-thick bonded overlay. The research project included experimental testing to measure the evolution of the structural capacity and the cracking behavior of two slab panels with the same configuration and dimensions. Under laboratory cyclic loading, the overlaid slab panel showed some fine horizontal cracks progressing along the interface between the overlay and the substrate slab. The finite-element modeling revealed that the flexural crack pattern significantly impacted the stress field near the overlay interface. Flexural cracking generated stress perpendicular to the interface (normal) in the area located near the flexural crack. The magnitude of the normal stress at the interface increased with bending moment. This can produce local debonding at the overlay interface located near a flexural crack. Cyclic loading was found to promote this possible interface cracking mechanism resulting from fatigue rupture of the bond between the overlay and substrate. © 2013 Elsevier Ltd. All rights reserved. Source


Sebaibi N.,Ecole Des Mines de Douai | Sebaibi N.,University Djilali Liabes | Sebaibi N.,Ecole Superieure dIngenieurs des Travaux de la Construction de Caen | Benzerzour M.,Ecole Des Mines de Douai | And 2 more authors.
Construction and Building Materials | Year: 2013

This paper proposes a new mix design method for self-compacting concrete (SCC). The proposed method determines the packing factor "PF" (aggregate content), following which, silica fume powder is used to increase strength and to obtain better workability of fresh paste. The compressible packing model, the Chinese method and the FN EN 206-1 standard for mixture design of SCC are used under this method. Tests on slump flow, and compressive strength were carried out and the results indicate that medium strength can be produced successfully using this method. © 2013 Elsevier Ltd. All rights reserved. Source


Saussaye L.,Ecole Superieure dIngenieurs des Travaux de la Construction de Caen | Saussaye L.,University of Caen Lower Normandy | Boutouil M.,Ecole Superieure dIngenieurs des Travaux de la Construction de Caen | Boutouil M.,University of Caen Lower Normandy | And 3 more authors.
Road Materials and Pavement Design | Year: 2013

The reuse of soils after adding binder agents results in the improvement of their physical and mechanical characteristics, allowing them to be reused in several geotechnical applications. Our ongoing research work is aiming at assessing the influence of chloride and sulfate ions, introduced as NaCl and CaSO4·2H2O, on physical and mechanical properties of treated soils.At 10 g·kg-1 of dry soil, the chloride ions' presence can affect the stabilisation process of treated soils with hydraulic road binder, but the strengths are still suitable for a reuse in sub-base layer. With the same content, sulfate ions can generate an important swelling, along with losses of strengths during suitability tests. In standard cure, these losses are less severe. © 2013 © 2013 Taylor & Francis. Source


Saussaye L.,Ecole Superieure dIngenieurs des Travaux de la Construction de Caen | Boutouil M.,Ecole Superieure dIngenieurs des Travaux de la Construction de Caen | Baraud F.,University of Caen Lower Normandy | Leleyter L.,University of Caen Lower Normandy
Engineering Geology | Year: 2015

The use of soils after treatment with hydraulic binders results in the improvement of their physical and mechanical characteristics for geotechnical applications. The influence of sulfate and chloride ions, introduced as CaSO4·2H2O and NaCl, on physical and mechanical properties of a treated soil is investigated.For the considered soil, in the presence of one of these anions, in accelerated cure conditions, important volumetric swellings due to high concentrations in sulfate ions are the only disturbances observed. The co-addition of sulfate and chloride ions induces both important volumetric swellings and loss of indirect tensile strengths. Structural modifications are observed by scanning electron microscopy. © 2015 Elsevier B.V. Source

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