std::remove_const with const references

Question

Why does std::remove_const not convert const T& to T&? This admittedly rather contrived example demonstrates my question:

#include <type_traits>

int main()
{
    int a = 42;
    std::remove_const<const int&>::type b(a);

    // This assertion fails
    static_assert(
        !std::is_same<decltype(b), const int&>::value,
        "Why did remove_const not remove const?"
    );

    return 0;
}

The above case is trivially easy to fix, so for context, imagine the following:

#include <iostream>

template <typename T>
struct Selector
{
    constexpr static const char* value = "default";
};

template <typename T>
struct Selector<T&>
{
    constexpr static const char* value = "reference";
};

template <typename T>
struct Selector<const T&>
{
    constexpr static const char* value = "constref";
};

int main()
{
    std::cout
        << Selector<typename std::remove_const<const int&>::type>::value
        << std::endl;

    return 0;
}

In the above example, I'd expect reference to be shown, rather than constref.