A.K.TAYLOR and F.M.KHALAF, Napier University, Edinburgh

ISO and CEN Codes use a method for calculating the compressive strength of masonry which involves the use of a reference or “normalised” unit size. An empirical equation for the shape factor, 5, derived in 1992 was based on tests an ordinary Portland cement concrete blocks. A comparison is made between the results of the present tests on lightweight pulverised fuel ash (pfa) concrete blocks and those predicted by the formula.