LHOIST Recherche et Developpement

Nivelles, Belgium

LHOIST Recherche et Developpement

Nivelles, Belgium
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Lhoist Recherche Et Developpement | Date: 2015-07-10

The invention concerns the use of an aqueous suspension of solid particles of a calcium/magnesium compound of formula (A): nCa(OH)_(2).mCaCO_(3).aMgO.bMg(OH)_(2).cMgCO_(3).I as an agent regulating the breaking of a bitumen emulsion. The invention also concerns a bituminous road material obtained by mixing a solid mineral fraction with a cationic bitumen emulsion of the type binder in water, characterised in that it involves adding, to the mineral fraction, an aqueous suspension of solid particles of a calcium/magnesium compound of formula (A). The invention also concerns a method for preparing a material according to the invention and the use of same for producing surface courses, tack coats or temporary surface courses. The invention finally concerns a method for obtaining a tack coat by spreading a cationic bitumen emulsion, comprising a step of applying an aqueous suspension of solid particles of a calcium/magnesium compound of formula (A).

Fourmentin M.,University Paris Est Creteil | Faure P.,University Paris Est Creteil | Rodts S.,University Paris Est Creteil | Peter U.,LHOIST Recherche et Developpement | And 3 more authors.
Cement and Concrete Research | Year: 2017

We show that it is possible to follow the liquid transfer between a cement paste and a porous medium in contact with it, by analysing the evolution of the distribution of 1H NMR relaxation times. This in particular makes it possible to see that whatever the initial water fraction in the paste, a porous medium with sufficiently small pores can rapidly extract a significant amount of water from this paste. Afterwards, during the hydration process, the cement paste progressively gets water back from this porous medium. The amount of water thus extracted by the paste finally appears to just compensate the volume loss due to water consumption by the hydration process. © 2017 Elsevier Ltd

Nerincx N.,ISL Ingenierie | Bonelli S.,IRSTEA | Puiatti D.,DPST Consulting | Herrier G.,Lhoist Recherche et Developpement | And 3 more authors.
E3S Web of Conferences | Year: 2016

Nowadays soil treatment with lime in civil engineering is widespread in many countries on all continents, within several construction fields. The interest of the hydraulic works community regarding this technique is currently growing. It has been indeed shown during the last decade that appropriate treatment technologies provide lime treated soils with high level properties such as excellent homogeneity, low permeability, internal and external erosion resistance and mechanical stability. Those have been shown in laboratory and for some properties with full scale experiments. The so conferred soil properties can lead to innovative earthfill dams and dikes designs by addressing some of the typical designer's problems, such as stability, watertightness, internal erosion, surface protection and flood control. However, lime treated soil external erosion resistance is still to be quantified in the field for proper designing and dimensioning of lime treated soil external erosion protection or spillways. With this purpose, an experimental earthfill dike has been built along the river Vidourle (France) in July 2015, in the frame of the French R and D program "DigueELITE". This 50 m long and 3,5 m high dike is made of lime treated silt and is provided with sensors (succion, water content and temperature) and piezometer in order to be monitored. It will also be tested against surface erosion. The final objective of this R and D program is to provide guidelines for designing innovative overflow resistant earthfill dikes. This article describes the performance reached by lime treated soils and associated design requirements and application; the experimental dike construction and lessons learned; the monitoring program; the dike design perspectives opened by soil treatment. © 2016 The Authors, published by EDP Sciences.

Fourmentin M.,University Paris Est Creteil | Faure P.,University Paris Est Creteil | Gauffinet S.,University of Burgundy | Peter U.,LHOIST Recherche et Developpement | And 4 more authors.
Cement and Concrete Research | Year: 2015

Abstract The acceleration of a cement paste setting as a result of lime addition may be shown from isothermal calorimetry measurements. We investigated the underlying mechanisms through two techniques that provide information on porous structure (using Nuclear Magnetic Resonance) and mechanical properties (elastic modulus measured by rheometry). The correlation of the two sets of results on a cement paste clearly reveals the successive steps of setting, and particularly highlights the so-called induction period. We show that this induction period disappears in the presence of lime, leading to an acceleration of the setting. We also show that beyond some critical concentration of added lime the acceleration of setting is negligible. © 2015 Elsevier Ltd.

Fourmentin M.,University Paris Est Creteil | Ovarlez G.,University Paris Est Creteil | Ovarlez G.,Solvay Group | Faure P.,University Paris Est Creteil | And 4 more authors.
Rheologica Acta | Year: 2015

The rheological properties of a suspension of lime in water (lime putty) are studied with the help of creep tests in a wide range of deformations including very small values. The results are compared with those obtained with a cement paste and several similarities between the two systems are observed. It is shown that the apparent yield stress of a lime suspension is the sum of two components: one due to standard reversible colloidal interactions and one due to the formation of a brittle structure associated with the formation of links due to dissolution–precipitation mechanisms. This second component increases with the time of rest as the square root of time, and the corresponding structure irreversibly breaks as soon as some significant deformation has been imposed. We show that similar structures are formed at concentrations between 25 and 34 % (solid volume fraction) and evolve in a similar way when the time is scaled by a factor decreasing with the solid fraction. © 2015, Springer-Verlag Berlin Heidelberg.

Fourmentin M.,University Paris Est Creteil | Faure P.,University Paris Est Creteil | Pelupessy P.,Ecole Normale Superieure de Paris | Sarou-Kanian V.,Conditions Extremes Materiaux a Haute Temperature et Irradiation | And 5 more authors.
Construction and Building Materials | Year: 2016

Hemp concrete used as a construction material is known to provide excellent thermal insulation and hydric regulation, and prevents condensation. Initial water content in the hemp and water exchanges between hemp and binder play a major role in these processes. Here we study how hemp absorbs liquid water. In that aim we rely on 1H NMR (Nuclear Magnetic Resonance) measurements which make it possible to distinguish water situated inside from water situated outside the hemp. Then, following the evolution of the distribution of NMR relaxation times we are able to quantify the effective amount of water entering the hemp as a function of time. We show that such a measure is better controlled than usual techniques such as weighing an immersed sample or the TC (Technical Committee) RILEM (Réunion Internationale des Laboratoires et Experts des Matériaux, systèmes de construction et ouvrages) method which cannot easily distinguish water inside hemp from water situated outside or wetting the external hemp surface. The water absorption in hemp occurs in two steps: about half the water enters the material in a time of the order of a minute, while the second half of water slowly penetrates over a time of the order of three days. Finally, from 1H micro NMR imaging we show that the first step corresponds to water entering the pith while the second one corresponds to water diffusing in the wood part of the shiv. © 2016

Faure P.,University Paris Est Creteil | Peter U.,LHOIST Recherche et Developpement | Lesueur D.,LHOIST Recherche et Developpement | Coussot P.,University Paris Est Creteil
Cement and Concrete Research | Year: 2012

The water transfers between the different phases of a Hemp Lime Concrete (HLC) were followed by NMR measurements. Due to the very different values of the NMR relaxation times of water contained in the different phases of the material the respective amounts of water within the hemp and in the mineral binder can be determined from an analysis of the time evolution of the distribution of T 1 relaxation time of the whole sample. Reliable quantitative estimations in the different phases were obtained, as confirmed by the agreement between the total mass deduced from NMR and the weighted mass at any time. It is shown that for a sealed sample a significant water amount is initially absorbed in the hemp then progressively migrates towards the binder, which supplies additional water for the hydration reactions. For an open (drying) sample the same process occurs but a significant amount of water evaporates, and the hemp dries more rapidly than binder. © 2012 Elsevier Ltd. All rights reserved.

Lesueur D.,Lhoist Recherche et Developpement | Peter U.,Lhoist Recherche et Developpement | Verhelst F.,Lhoist Group Marketing
Cement, Wapno, Beton | Year: 2011

Quicklime is a key component of Autoclaved Aerated Concrete (AAC), with typical quicklime contents of order 15 wt.% in Europe. It is the mostly used source of calcium oxide that eventually ends up as tobermorite in the final product. In this paper, we describe the research performed at Lhoist in order to assess the influence of quicklime on AAC. Several types of quicklimes were used, differing by their origin and reactivity. They were incorporated together with other fixed ingredients (cement, quartz,.) in several AAC recipes with final densities ranging from 350 to 550 kg/m3, corresponding to the European P2 - 0.35, P2 - 0.4 and P4 - 0.55 classes (EN 771-4). The study consisted first in following the green cake expansion of the different recipes. Then, the green cakes were autoclaved for 10 hours at 11 bars of steam pressure. The obtained AAC blocks were then tested for compressive strength and density. The study showed that quicklime reactivity had low effect on green cake penetration value. However, quicklime reactivity had a major effect on green cake expansion. Too reactive a quicklime generated a poor pore structure as detected by a fallback effect and a below-specification compressive strength of the low density AAC. Then, quicklime slaking curve was not sufficient to anticipate the green cake expansion for a given recipe. Quicklimes with similar reactivity but different origin could had very different behaviour in the AAC. Finally, the behaviour of the too-reactive quicklimes would probably have been easily corrected by decreasing the water temperature.

Nguyen T.T.H.,ParisTech National School of Bridges and Roads | Cui Y.J.,ParisTech National School of Bridges and Roads | Tang A.M.,ParisTech National School of Bridges and Roads | Herrier G.,Lhoist Recherche et Developpement | And 3 more authors.
Unsaturated Soils: Research and Applications - Proceedings of the 6th International Conference on Unsaturated Soils, UNSAT 2014 | Year: 2014

Unsaturated hydraulic conductivity is key factor governing soil swellings under the effect of frost because it conditions the water transfer driven by the cryo-suction generated by soil freezing. In this study, the unsaturated hydraulic conductivity of a compacted untreated and lime treated silty soil was determined using two methods: 1) calculations based on a capillary tube model involving the pore size distribution curve obtained by the technique of mercury intrusion porosimetry technique, and 2) determination by the instantaneous profile method using the results from isothermal infiltration/drying tests. This enables the two methods to be compared and discussed. Significant difference was observed, showing the limitation of the capillary tube model used in predicting the hydraulic conductivity of soils. However, the calculated hydraulic conductivity-suction curve presents a similar shape to the measured one, suggesting that the main mechanism considered in the model is appropriate. © 2014 Taylor & Francis Group.

Nguyen T.T.H.,ParisTech National School of Bridges and Roads | Cui Y.J.,ParisTech National School of Bridges and Roads | Herrier G.,Lhoist Recherche et Developpement | Tang A.M.,ParisTech National School of Bridges and Roads
Geotechnical Engineering for Infrastructure and Development - Proceedings of the XVI European Conference on Soil Mechanics and Geotechnical Engineering, ECSMGE 2015 | Year: 2015

The hydraulic conductivity is a key parameter in evaluating the water transfer in soils. For the subgrade soils treated with lime, it is also an important factor to be accounted for when assessing the soils resistance to frost. To the authors' knowledge, the effect of lime treatment on the hydraulic conductivity of unsaturated soil is still subject to debate. In this study, the hydraulic conductivity of a limetreated silty soil was determined experimentally using an infiltration column equipped with tensiometers at different heights. Three quicklime dosages were considered: 0% (untreated soil), 2% that corresponds to the lime fixation point (LFP), and 4%. The effect of curing times was examined: as-treated, 28 days and 90 days. The saturated hydraulic conductivity was also determined by variable head permeability test. In order to complete the results for applying the simultaneous profile method when determining the unsaturated conductivity, the water retention curves were determined for each configuration. It appears that after a 28 days curing time, the hydraulic conductivity increases, especially in the case of high lime dosage. This increase can be attributed to the effect of flocculation. On the contrary, after a longer curing time of 90 days, the significant pozzolanic reactions led to a decrease of hydraulic conductivity. © The authors and ICE Publishing: All rights reserved, 2015.

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