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Showing 4 results for Cbr Value

S.a. Naeini, R. Ziaie_moayed,
Volume 7, Issue 2 (6-2009)
Abstract

In recent years, soil reinforcement is considered of great importance in many different civil projects. One of the most significant applications of soil reinforcement is in road construction. Sub grade soil and its properties are very important in the design of road pavement structure. Its main function is to give adequate support to the pavement from beneath. Therefore, it should have a sufficient load carrying capacity. The use of geosynthetics in road and airfield construction has shown the potential to increase the soil bearing capacity. One category of geosynthetics to particular, geogrid, has gained increasing acceptance in road construction. A geogrid is a geosynthetic material consisting of connected parallel sets of tensile ribs with apertures of sufficient size to allow strike-through of surrounding soil, stone, or other geotechnical material. Geogrid reinforcement of sub grade soil is achieved through the increase of frictional interaction between the soil and the reinforcement. Geogrid have been successfully used to provide a construction platform over subgrades. In this application, the geogrid improves the ability to obtain compaction in overlying aggregates, while reducing the amount of material required be removing and replacing. Relative agreement exists that substantial benefits can be achieved from the inclusion of geogrids within the pavement systems however, the quantity of the improvement is in relative disagreement. This paper presents the effects of plasticity index and also reinforcing of soft clay on CBR values. Three samples of clay with different plasticity index (PI) values are selected and tested without reinforcement. Then by placing one and two layer of geogrid at certain depth within sample height, the effects of reinforcement and PI on CBR values are investigated in both soaked and unsoaked conditions. The results shows that as the PI increase the CBR value decreases and reinforcing clay with geogrid will increase the CBR value.
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. 


M. A. Khan,
Volume 11, Issue 1 (5-2013)
Abstract

Owing to the proximity of certain locations to the thermal power stations, it has always been efforts of Engineers to enhance

the flyash utilization rate in various Civil Engineering Constructions adopting suitable strategies. In the present study, a soilflyash

interface mechanism has been evolved using different soil-flyash ratios to upgrade significantly stabilization of supporting

medium based on CBR tests. The study confirms soundness of approach when a particular interface arrangement gives high

flyash utilization rate along with many fold increase CBR values. A study was carried out to investigate the interface effect of

soil-flyash layered system in terms of CBR values so that an optimum arrangement can be achieved by using flyash in

combination with soil. In this study, 18 samples of different ratios of soil and flyash (1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3) with three

sets of interfaces N = 2, 4 and 6 were tested to arrive at the most optimized combination of soil and flyash. The results indicate

that the CBR value optimized at soil-flyash ratio 1:2.5 and number of interface N = 4. The present study reveals that soil with

flyash when used in layered system with various numbers of interfaces gives considerable improvement in CBR values. In the

above arrangement about 71 % of flyash and 29 % of soil thus contributing significantly in utilization of flyash in subgrade of

flexible pavements. In the overall study, three equations for number of interfaces N = 2, 4 and 6 have also been developed in

terms of soil-flyash ratio and CBR value, so that CBR value can directly be obtained by substituting the value of soil-flyash ratio

at a particular number of interfaces.


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.

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