Of course, aggregates can be replaced in some cases. Bricks can be made out of clay, and that is done in Northern Ireland. Clay tiles can be used for roofs. Most of the tiles used in Northern Ireland are imported from Great Britain, and they are no cheaper for being put on a boat and taken across the Irish sea. In fact, they are much pricier than concrete tiles.
Many people prefer a slate roof, but few can afford such roofs nowadays.
Asbestos is cheaper but carries environmental concerns. We surely have environmental concerns about asbestos nowadays. Pipes used to be made of clay. Now the smaller diameters are made of plastic, but beyond a certain size the only materials with the necessary structural strength are concrete or steel. We make a lot of concrete pipes in Northern Ireland, and certainly some very large ones.