Workability and mechanical properties of mortars containing a bioadmixture manufactured with extracellular substances [Ouvrabilit́e et performances ḿecaniques de mortiers contenant un bioadjuvant ̀a base de substances extra-cellulaires]
He H.,IMFS |
Serres N.,IMFS |
Meylheuc T.,French National Institute for Agricultural Research |
Materiaux et Techniques | Year: 2013
A bio-admixture was used in mortar and its influence on the properties of fresh and hardened mortars was investigated. Various concentrations of bioadmixture (0.5; 1.5; 2.5%) were added to mortars containing CEM I or CEM V cements. In mortars, water-cement ratio was kept constant (W/C = 0.5). The initial slump and slump loss for various mortar mixtures were determined. The compressive and flexion strengths were observed after 28 days water curing. The first experimental results show that the admixture acts as a plasticizer on mortars because it increases their workability, whatever the admixture rate for CEM V, while only mortars with 1.5% and 2.5% of admixture were significantly greater than the un-admixtured mortar with CEM I. In addition, for the CEM I based mortar, the sample containing 2.5% of bioadmixture has a lower compressive strength than that of the mortar without bioadmixture; while for a bioadmixture rate in the range of 0.5-2%, compressive strength are comparable. Flexural strengths of CEM I with 2 and 2.5% of bioadmixture based mortars are comparable. For CEM V based mortars, compressive strength is the same for rates of 1, 1.5 and 2% of bioadmixture and superior than that of the un-admixtured mortar, which has a compressive strength similar to mortars with 0.5 and 2.5% of bioadmixture. Finally, the bioadmixture has no effect on the flexural strength of the CEM V based mortar, except for mortar containing 1% of bioadmixture. © 2013 EDP Sciences.
Mustapha H.,University of Science and Technology of Oran |
Cherifa H.,Saida University |
Abdelkrim H.,Saida University |
Abdellah G.,IMFS |
Desalination and Water Treatment | Year: 2014
Abstract: In this study, an up-to-date analysis was performed on pollution conditions in the Wadi Saïda drainage basin (North West Algeria). We focused on the water in the streams that drain the basin. The results include a number of quality parameters and give the spatio-temporal variations in surface water pollution indicators over a period of several years. The principal parameters related to the monitoring and evaluation of the pollution of surface water are measured and analyzed. These parameters include the suspended solids, organic matter, nitrate, nitrite in addition to biochemical oxygen demand, and chemical oxygen demand. Analysis and comparison with other basins in Algeria are also performed. In the light of the results, a plan is proposed for the land use and protection of groundwater in Saida. © 2013 Balaban Desalination Publications. All rights reserved.
Influence of grain size changes on the turbidity measurement of suspended solid fluxes in watercourses [Influence de la granulométrie des particules sur la mesure par turbidimétrie des flux de matières en suspension dans les cours d'eau]
Thollet F.,IRSTEA |
Le Coz J.,IRSTEA |
Antoine G.,Électricité de France |
Francois P.,IMFS |
And 3 more authors.
Houille Blanche | Year: 2013
Since 2009, Irstea has been measuring suspended sediment fluxes on the Arc river in the French Alps, a great sediment contributor, by using turbidity monitoring systems at four stations; each of them is associated with a discharge measurement system. High frequency turbidity measurement is converted into Suspended Sediment Concentration (SSC) through a SSC = f(turbidity) relation, thanks to sample analysis. Nevertheless a mean relation is not relevant for all flood events for our study site since turbidity sensors do not give the same response for a given SSC. Therefore with the event-scale relation, the uncertainty on the sediment flux can typically reach 30% and sometimes exceed 80% compared with the mean relation while the uncertainty on annual flux remains acceptable (less than 15%) A hypothesis to explain this variable relation is the variation of the SSC grain size in the river. This paper presents the results obtained with an experiment showing the variations of sensitivity of the turbidity sensor to suspensions with different grain size. It isfound to be correlated inversely proportional to the median diameter of the particles. Strategy for managing turbidity calibrations is thus as important as rating curves for hydrometric stations for estimating suspended sediment fluxes. The uncertainty on rating curves is lower especially for the event scale. © Société Hydrotechnique de France, 2013.
Terfous A.,IMFS |
Hazzab A.,Saida University |
Powder Technology | Year: 2013
This paper presents a relationship for calculating the drag coefficient of a spherical particle. The results obtained were validated using experimental data, including comparison with results from other relationships such as certainty analysis. The validation indicated that the proposed relationship is easier to apply and produces the best results. In addition, a relationship based on the characteristics of both the fluid and the particles was established to calculate directly the settling velocity of a spherical particle in a fluid at rest. The settling velocity values obtained with the proposed relationship were validated using experimental data and the model proved to be reliable and precise. © 2013 Elsevier B.V.