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Search Results: 1 - 10 of 1048 matches for " Resilient modulus "
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Effect of Compaction Moisture Content on the Resilient Modulus of Unbound Aggregates from Senegal (West Africa)  [PDF]
Makhaly Ba, Meissa Fall, Oustasse Abdoulaye Sall, Fatou Samb
Geomaterials (GM) , 2012, DOI: 10.4236/gm.2012.21003
Abstract: This paper presents the results of research conducted to investigate the effect of compaction moisture content on Resil- ient Modulus (Mr) of unbound aggregates. Three different aggregates (GRB, Basalt and Bandia limestone) was collect- ed from different sites within Senegal and then subjected to repeated load triaxial tests. Test results showed that the ef- fect of compaction water content is more significant in the dry side than in the wet side. The compaction water content has less effect on the GRB and the Basalt than on the Bandia limestone. GRB and Basalt are cohesionless materials and allow water to drain even during the compaction procedure. Change in water content increases as the compaction water content increases because of the drainage of the excess water during the compaction and loading procedures. For GRB and Basalt, at Wopt + 1.5%, most of the excess water is drained during the compaction of the sample and continue to be drained during the Resilient Modulus test. For the Bandia limestone, this drainage is less significant due to cohesion, absorption and hydratation.
Resilient Modulus of Unbound Aggregate Base Courses from Senegal (West Africa)  [PDF]
Makhaly Ba, Meissa Fall, Fatou Samb, Déthié Sarr, Mapathé Ndiaye
Open Journal of Civil Engineering (OJCE) , 2011, DOI: 10.4236/ojce.2011.11001
Abstract: This paper presents the results of research conducted to investigate the Resilient Modulus (Mr) of unbound aggregates used as pavement layer in Senegal (West Africa) as well as the effect of water content and density on the Resilient Modulus of the materials tested. Four different aggregates was collected from different sites within Senegal and then subjected to repeated load triaxial tests. Test results showed that the Bandia limestone is around 44% stiffer than the basalt, and 71% to 104% stiffer that the Black and the Red quartzites (GNB and GRB). The basalt is 21% to 43% stiffer than the GNB and the GRB. Basalt specimens compacted at Wopt– 2% were 30% stiffer than basalt specimens compacted at Wopt and 40% stiffer than those com- pacted at Wopt+ 2%. The Summary Resilient Modulus (SRM) at Wopt– 2% is 22% higher than SRM at Wopt and 35% higher than SRM at Wopt+ 2% for the GRB and the GNB. The SRM at Wopt– 2% is 30% higher than SRM at Wopt and 40% higher than SRM at Wopt+ 2%, for the Basalt. For the Bandia limestone, the SRM at Wopt– 2% is 81% higher than SRM at Wopt and 126% higher than SRM at Wopt+ 2%. Results show also that the Resilient Modulus increases around 25% when relative density increases from 77% to 119% and the variation is more significant at high stress states than at low stress state. Results of statistical analysis and coefficients of determination (R2) showed that the Uzan and NCHRP models are more suitable to predict the Resilient Modulus of the aggregates tested.
Estimation of Resilient Modulus of Unbound Granular Materials from Senegal (West Africa)  [PDF]
Adama Dione, Meissa Fall, Yves Berthaud, Makhaly Ba
Geomaterials (GM) , 2013, DOI: 10.4236/gm.2013.34022
Abstract:

The resilient modulus (Mr) is an important parameter which describes the mechanical behavior of unbound granular materials. However, this parameter can be determined from physical properties. This paper presents the relationship between resilient modulus and physical properties of Quartzite from Bakel (GB), Basalt from Diack and Bargny and Bandia limestones. Simple and multiple regression method by stepwise are used to establish linear and nonlinear relations to predict the resilient modulus. The results showed no significant correlation for Basalt, a weak estimation of the modulus for GB and good prediction of resilient modulus for limestone. These results also showed that the model of Uzan is more suitable to predict the resilient modulus than NCHRP model and the resilient modulus is better predicted in nonlinear relationship.

Influencia de la Tipología del Ligante en las Propiedades Mecánicas de una Mezcla Asfáltica Densa
Reyes-Ortiz,Oscar J; Valdés,Gonzalo A; Salazar,Mario;
Información tecnológica , 2009, DOI: 10.4067/S0718-07642009000600006
Abstract: this paper presents the analyses of the influence of different asphalt types on the mechanical properties of a dense asphalt mixture. two penetration binders, ca 60/80 and ca 80/100, and styrene-butadiene-styrene (sbs) a modified polymer binder were used. mechanical properties as cohesion, resilient modulus, indirect tensile resistance and rutting were evaluated. the results allow concluding that the mixture fabricated with polymer modified binder presents a better behaviour in the mechanical properties evaluated. also, the compaction energy and test temperature have greater influence on the mechanical properties in mixtures fabricated with penetration binder than those done with polymer modified binder.
Desempenho mecanico de misturas asfálticas confeccionadas com agregados sintéticos de argila calcinada
Frota, C. A.;Nunes, F. R. G.;Silva, C. L.;Melo, D. M.;Santos, M. G. R.;
Ceramica , 2007, DOI: 10.1590/S0366-69132007000300007
Abstract: a substantial number of municipal districts in the state of amazonas are located in areas which are poor in stony materials. and this has led pavement builders into adopting alternatives which have historically produced pavements with low mechanical strength. whist more effective and appropriate from a technical standpoint, the asphalt concrete has been usually left aside due to the referred lack of stony materials. because of the specific situation in the state of amazonas the adoption of synthetic calcinated clay aggregates (scca), with an abundant raw material (clay) in the state of amazonas is recommended in lieu of the traditional practice. previous works carried out by the federal university of amazonas geotechny group have demonstrated that the clay soil commonly used in the production of ceramic materials can yield synthetic aggregates with adequate mechanical properties. in this research work, samples featuring similar characteristics as those of the soils in question have been found along the br-319 highway connecting the manaus (am) city to porto velho (ro) city. the transportation structure in general is in deplorable conditions. justifiably so, the recovery of this highway has been earmarked as one of the targets for the ministry of transportation. in this study, asphalt mixtures were blended with synthetic aggregates and pebbles taken from the river bed in order to compare the mechanical performance of such mixtures by means of the determination of the resilient modulus (rm). the results, as a rule, have shown that the asphalt mixtures comprising synthetic calcinated clay aggregates when compared with those comprising the naturally-found material (river bed pebbles) have shown: (a) greater tensile and resilient modulus strengths; (b) low deformation tendency, as well as a considerable elastic recovery and (c) less susceptibility to permanent deformation.
Resilient Modulus of Compacted Lateritic Soils from Senegal at OPM Conditions  [PDF]
Fatou Samb, Meissa Fall, Yves Berthaud, Makhaly Ba
Geomaterials (GM) , 2013, DOI: 10.4236/gm.2013.34021
Abstract:

Repeated load triaxial tests were performed on five compacted gravel lateritic soils collected from different locations in Senegal: Sébikotane, Dougar, Pa Lo, Mont-Rolland and Ngoundiane. The study revealed that resilient modulus decreases with the increase of the bulk and deviatoric stress in constant confining pressure. In addition, resilient modulus increases with the percentage of cement for appreciably equal contents of moisture. This effect tends to stop for higher stress. Besides, correlations were made with some models of resilient modulus such as the Uzan-Witczack model (Witczack and Uzan, 1988 [1]) and the National Highway Research Program (NCHRP) model (2004 [2]). The study confirms that both models give very good results with the best correlations being obtained with the Uzan-Witczack model.

Soil Subgrade’s Characterization and Classification of Thies (Senegal, West Africa) on a Radius of 2.5 Kilometers along Five Roads  [PDF]
E.H.B.M. Niakhate, Séni Tamba, Makhaly Ba, Adama Dione, Issa Ndoye
Geomaterials (GM) , 2016, DOI: 10.4236/gm.2016.61001
Abstract: This article explains the results of a study conducted on the characterizations of subgrade soils in the region of Thies. The road platforms are mainly composed of a background soil, which is generally overlapped by a surface layer that plays two roles. Firstly, it protects the soil structure, ensures the leveling, and facilitates the movement of vehicles. Secondly, it brings harmony in the mechanistic characteristics of the materials that compose the soil while improving the long-term life force. The methodology consisted in taking samples of subgrade soil along the roads all over the region of Thies in a 5 km diameter span. The identification tests allowed the Thies-Tivaoune, Thies-Khombole and Thies-Noto axes are characterized by tight sands, poorly graded size. While Thies Pout-axis is characteristic of severe solid particle size and spread well graded and serious to spread and well graded particle size. Finally the Thies-Montrolland axis is characterized by severe to very tight particle size and graduated to spread and serious and well graded particle size. The specific gravity values found Proctor test shows the presence of sand, sandy laterite and laterite. In the target area, polished soils of the A-3 type according to the AASHTO classification system are the most represented with 60%, followed by the A-2-6 type 25%, and the A-2-4 type with 9%, which are typical of gravel, clay, and silty sands. Soils of the A-1-b type (2%) typical of roc fragments, sands and clay are also represented. Polished sands of the A-3 type have a better efficiency on road infrastructures than other types of soil listed above. Finally, we’ve also noted the presence of soils of the A-2-7 and A-4 types with the low percentage of 2%. Subgrade soils of class S4 are the most represented with 58%, followed by those of class S5 with 42%. Samples of the Thies-Montrolland road have a claylike plasticity (CL or CH group), while those of the Thies-Pout road belong to the ML or OL and CL or OL groups with a tendency mostly directed to the CL or OL group. All these results confirm the very nature of soils on the two roads and put the light on the presence of lateritic materials with certain plasticity.
Preliminary k-Values of Unbound Natural Quartzitic Gravels for Mechanistic-Empirical Pavement Design  [PDF]
Edmund Obeng, Yaw A. Tuffour, Daniel A. Obeng, Bernard Koranteng-Yorke
Open Journal of Civil Engineering (OJCE) , 2017, DOI: 10.4236/ojce.2017.74034
Abstract: The generalized constitutive model relating the resilient modulus (MR) of flexible pavement layer materials to stress state, adopted by the Mechanistic-Empirical Pavement Design Guide (MEPDG), contains a set of constants known as k-values (k1, k2, and k3) which are associated with the physical state of the layer materials. In Ghana, natural gravels constitute the predominant and sometimes the sole layer materials for most flexible pavements yet representative k-values of gravel materials, have not been determined to permit full application and implementation of the mechanistic-empirical design concept to pavements involving such materials. In this study, k-values characterising typical natural quartzitic gravels used for road construction in the country were derived by regression techniques from MR values determined using laboratory repeated load triaxial test. Using multiple linear regression technique, correlation relationships were then developed
Cambios dinámicos y mecánicos de una mezcla asfáltica densa por las propiedades del asfalto y la energía de compactación
Reyes-Ortiz,Oscar J.;
Ingeniería y Desarrollo , 2009,
Abstract: the objective of this study was to evaluate the influence of three types of asphalt with different characteristics (60/70 of penetration, 85/100 of penetration and polymer modified asphalt) and compaction energy in the mechanical and dynamic changes of the dense asphalt mixture, used as a rolling layer by specifications idu. the ideal asphalt content was determined by the marshall. the mechanics and dynamic characterization of the mixture, was realized with diametral compression tests at 15 ° c, rutting with 900 mpa and 60° c, resilient modulus with 15, 20 and 30 °c, 5 hz frequency and the cohesion curve through the characterization universal binders (ucl) test with 0, 10, 20, 30 and 40° c. the study found that the results show that the mixture prepared with asphalt 60/70 presents highter resilient modulus value at temperatures studied and the mixture manufactured with modified asphalt has rutting lower than conventional asphalt. finally, resistance to traction and indirect cohesion curve state is best for the modified asphalt
CARACTERIZACIóN DINáMICA DE UNA MEZCLA ASFáLTICA SOMETIDA A LAS CONDICIONES AMBIENTALES DE BOGOTá
Rondón,Hugo Alexander; Reyes,Fredy Alberto; Vacca,Hermes Ariel;
Revista EIA , 2010,
Abstract: the paper presents the evolution of the resilient modulus, permanent vertical deformation, and fatigue law of hot mix asphalt (hma) when exposed to the weather conditions in the city of bogotá d.c. (colombia) for 29 months. the trend of mixture with the exposure time is to experience an increase in stiffness values, mainly due to age-hardening process of the asphalt binder. this increase in stiffness creates increased resistance to permanent deformation and decrease in fatigue life of the analyzed mixture. based on the resilient modulus evolution with time of exposure to the environment an equation to predict approximately the change for the fatigue life of the mixture is proposed.
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