How to concat strings so that trailing spaces remain

I have where clause where all fields are CHAR(10) type and may have trailing
spaces.

SELECT ...

FROM r1, r2

WHERE r1.c1 || r1.c2 || r1.c3 >= r2.c1 || r2.c2 || r2.c3;

This WHERE clause produces wrong result since || operator removes trailing
spaces.

Correct result is produced if || operator does not remove trailing spaces.

How to concat strings in this expression so that trailing spaces are
significiant or how to re-write this join condition so that trailing spaces
are used for comparison?

Andrus.