Laravel request URI not working

I have the following route group:

Route::group(['prefix' => 'admin'], function () {

     Route::get('/', 'PagesController@index');

     // some more routes...
});

In my layout file I have the following condition:

 @if (Request::is('admin/*'))
            @include('layouts.partials.admin_header')
 @else
            @include('layouts.partials.header')
 @endif

When I navigate to http://ift.tt/1XmTvHH it's not displaying in the admin header file?

via Chebli Mohamed