A low-density residential building development is to be demolished. An analysis of the materials used in its construction suggests it is, by mass, 57.0% concrete, 18.2% brick, 8.1% plaster, 3.0% steel, 1.6% wood, and the remainder made up of lime, tiles, and aluminium (from window frames).

(a) Assuming that the bricks and steel are recovered and recycled for reuse elsewhere if these buildings were to be traditionally demolished, would the resultant aggregate be suitable for recycled concrete aggregate (RCA)? Explain your answer carefully in terms of the key contaminants. Assume that the plaster is hydrated gypsum. 

(b) Were the bricks not recovered, the potential recyclate would fail RCA tests on the masonry content. Why is it important to keep masonry out of RCA? 

(c) How could the potential quality and value of the aggregate be improved. 

(d) Assuming the recycled aggregate is produced according to your recommendations to form RCA if the site is to be redeveloped as new high-density housing, is it likely that all the RCA could be reused? Explain your answer carefully, using 2-3 paragraphs.