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Showing 5 results for California Bearing Ratio

Malik Shoeb Ahmad, S. Salahuddin Shah,
Volume 8, Issue 4 (12-2010)
Abstract

 Roadways have a high potential for utilization of large volume of the fly ash stabilized mixes. In this study, an attempt has been made to investigate the use of Class F fly ash mixed with lime precipitated electroplating waste sludge–cement as a base material in highways. A series of tests were performed on specimens prepared with fly ash, cement and lime precipitated waste sludge. California bearing ratio (CBR) tests were conducted for 70%-55%fly ash, 8%cement, and 30%-45%waste sludge combinations. Results show that the load bearing strength of the mix is highly dependent on the waste sludge content, cement as well as curing period. The CBR value of fly ash mixed with electroplating waste sludge and cement has been increased to manifold and results the reduction in the construction cost of the pavement. The study also encourages the use of two potentially hazardous wastes for mass scale utilization without causing danger to the environment, vegetation, human and animal lives. 


Wen-Chao Huang,
Volume 12, Issue 3 (7-2014)
Abstract

When geogrid reinforcement is used as a treatment method for improving soft subgrade as a roadway foundation, a top layer of subgrade is usually excavated and backfilled with geogrid-reinforced aggregates. This treatment method produces an adequate platform for the planned roadway construction site, where heavy traffic loading is constantly moving. This paper presents a quantitative assessment of subgrade improvement by geogrid reinforcement based on numerical modelling and parametric studies. First of all, the preliminary numerical models were verified by comparing the analysis results with previous studies. Secondly, the major numerical models in this study were assumed to be a simplified simulation of a geogrid-reinforced two-layer system with an aggregate layer above a subgrade layer. The numerical models were applied a quasi-static loading and unloading cycle, in order to monitor the permanent deformation at the surface of the models. Afterwards, thickness of aggregate layer, and subgrade CBR values were varied in order to summarize the outcomes of each case. This approach makes it possible to quantify the effects of geogrid reinforcement and aggregate material in terms of an enhanced California Bearing Ratio (CBR) of a single subgrade clay layer. Results have shown that when the aggregate thickness is up to 450mm, the contribution of enhanced CBR is mostly from aggregate material. However, when the aggregate thickness is about 150mm with a relatively weak subgrade material, the inclusion of geogrid material can contribute about 50% of the enhanced value.
Adel Djellali, Abdelkader Houam, Behrooz Saghafi, Ali Hamdane, Zied Benghazi,
Volume 15, Issue 3 (5-2017)
Abstract

To study and predict the behavior of flexible pavement over expansive soils, a pavement structure was subjected to different laboratory and fieldwork experiments. The existing pavement was replaced and designed based on California Bearing Ratio (CBR) method, with a new one, and subjected to the traffic from various number of load cycles from 12.1 up to 155.52 kcycles of standard axle load (80 kN) through dual wheel assembly over a 6-month period. As the preliminary step, the deflection measurements were taken at the asphalt surface layer, using a Total station at different distances as function of truckload applications. The numerical analysis is carried out with the Finite Element software package PLAXIS version 2012. In the new model, the calculation of the transferred pressure to the pavement through contact area of tires is 3D it was turned into a 2D problem, and the pavement was subjected to a static loading using a ratio factor of dynamic additional charge. The materials’ behavior was simulated with nonlinear models: Mohr–Coulomb (MC) for pavement layers and soft-soil model (SSM) for the expansive subgrade, in saturated drained and undrained conditions. The results indicate that displacements under static loading in saturated drained conditions and when non-linear materials are present are the closest to field measured deflections.


G. P. Ganapathy, R. Gobinath, I. I. Akinwumi, S. Kovendiran, M. Thangaraj, N. Lokesh, S. Muhamed Anas, R. Arul Murugan, P. Yogeswaran, S. Hema,
Volume 15, Issue 3 (5-2017)
Abstract

Soils with poor engineering properties have been a concern to construction engineers because of the need to strike a balance between safety and economy during earthworks construction. This research work investigates the effects of treating a soil having poor geotechnical properties with a bio-enzyme to determine its suitability for use as road pavement layer material. The elemental composition and microstructure of the soil was determined using energy dispersive X-ray spectroscopy and scanning electron microscopy, respectively. The specific gravity, Atterberg limits, compaction, strength and permeability characteristics of the soil was determined for various dosages of the bio-enzyme. The mountain soil is classified as clayey sand and A-2–4, according to unified soil classification and AASHTO classification systems, respectively. With increasing dosage of the bio-enzyme, the plasticity index, maximum dry unit weight and permeability of the soil decreased, while its 28-day California bearing ratio value, unconfined compressive strength and shear strength increased. Consequently, the application of bio-enzyme to the soil improved its plasticity and strength, and reduced its permeability. It, therefore, became more workable and its subgrade quality was improved for use as a road pavement layer material. The stabilized soil can be suitably used for constructing pavement layers of light-trafficked rural (earth) roads, pedestrian walkways and bicycle tracks.



Volume 15, Issue 6 (9-2017)
Abstract

In this study, the shear strength parameters of the Kaolinite clay, as the control material, and the Kaolinite clay reinforced by different percentages of two different types of crumb rubber content have been evaluated. The consolidated drained and unconsolidated undrained triaxial and California bearing ratio tests have been conducted on the control and crumb rubber reinforced soils. Addition of crumb rubber would improve shear strength parameters such as cohesion, friction and dilation angles, stiffness and the ductility of the reinforced soil. 5, 10 and 15 % (by the weight of dry soil) of crumb rubber content were used in this study which were undergone confining stress levels of 100, 200 and 300 kPa and an optimum crumb rubber content is found, which results in the maximum bearing capacity of the soil. Also, due to the non-linearity of the failure mode of reinforced soil and inadequacy of Mohr–Columb envelope for describing the behaviour, a failure mode is proposed for the clay soils reinforced by crumb rubber. This failure criterion is useful for failure envelope of clay-rubber matrix.



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