There are a couple problems you might need to worry about - firstly the matrix materials (assuming cementitious) are alkaline and will eat away at the natural fibers in coconut shells. Secondly, the fibers don't make a good enough bond with the matrix, leading to poor interfacial strength. Both these aspects will lead to reduced life and strength. 

Best place to look for information on these subjects is under 'natural fiber reinforced concretes'. 

Thanks a lot Kaustubh. Your information is highly valued. But, I am thinking about using shell (Endocarp) only, not husk (mesocarp). (see attached image for reference). In that sense there will not be any problem of natural fibres bonding, I guess. And, as per the literature survey I done, using coated crushed shell in partial replacement of aggregate wont affect much on strength of design mix. (Attaching references). Please have a look.   

The Yerramala paper is the most relevant, but they also show 45% reduction in strength at 10% shell content. Moreover that strength is at 28 days. The  shell will degrade over longer periods than that, causing further long term reduction. In a pavement application you will have significant fatigue loads too, which cause failure through interfacial debonding. 

A lot of people have tried using natural fibers as reinforcement, as far back as the 60s, but we just keep seeing the same results over and over again. 

Natural micro organisms in biological materials also contribute to degradation. All of these issues make it infeasible  to use natural fibers in concrete. If I were in your place, and had access to cheap coconut shells on site, I would consider using them as fuel to offset asphalt heating costs :) 

Thanks a lot Kaustubh. 

I am done with literature review. And found the solutions for the problems mentioned above by Koustubh. But still, I am not satisfied with those solutions. 

So, If possible, can anyone provide me related articles? or references? like comparative study between the mechanical and thermal behaviour normal aggregates and crushed coconut shells as a aggregates or anything related to the same?  

Thanks a ton in advance.