a cbr based study evaluating subgrade strength of flexible pavements having soil flyash interfaces

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.