Weathering and decay of granitic rocks:: its relation to their pore network

A study is presented on the pore size distribution in granites, both fresh and artifically aged by freezing/thawing cycles (-20/110 degrees C), in the diameter range 0-25 nm, by nitrogen adsorption at -196 degrees C. The pore size distribution found permits a plausible explanation for the behaviour shown by these materials during degradation processes associated to fluid flows through their pores (thermoclasty and gelifraction). If low porous granites are used, artificial ageing has only a minor, limited effect on their pore network; however, changes in pore size distribution (diameter < 10 nm) are observed in samples where a pore network already exists in the unaltered samples. Changes in porosity observed upon artificial ageing are similar to those observed in historical buildings after natural decay. (C) 2000 Elsevier Science Ltd. All rights reserved.