d. Chemical Attack . Calcareous stones are subject to decomposition by 

 acids which may be formed by the combination of moisture and gases, such as 

 sulfur dioxide, which may be present in the air. A sandstone in which the 

 cementing material is calcium carbonate may also disintegrate under such 

 action, whereas a silicate would be more resistant. 



e. Rock Borers . Rock borers found in saltwater may penetrate and 

 destroy soft rock such as unconsolidated sandstone and hard clays. 



f . Exposure to Waves . Coastal structures are often located so that 

 parts of the structure may be subjected to nonbreaking, breaking, and 

 broken wave forces. Pressure due to nonbreaking waves will be essentially 

 hydrostatic. Breaking and broken waves exert additional pressures due to 

 the dynamic effects of the turbulent water in motion and the compression of 

 entrapped air pockets. These pressures may be much greater than those due 

 entirely to hydrostatic forces. Therefore, structures or parts of struc- 

 tures located in areas in which storm waves may break should be designed to 

 withstand much greater forces and moments than those structures which would 

 be subjected to only nonbreaking waves. Coastal structures may be damaged 

 more by the dislodging of stones from the structure by wave action than by 

 disintegration or breaking of individual stones. The deterioration of 

 stone due to abrasion may be most significant when it is subject to a 

 pounding surf carrying sand, gravel, and smaller stones. 



g. Exposure to Ice Floes . An analytical method of determining ice 

 forces on coastal structures is not known (U.S. Army, Corps of Engineers, 

 1971a); however, some data are available on ice pressures. Floating ice 

 fields may exert a major pressure on maritime structures when driven by 

 strong winds or currents by piling up huge ice masses. Stones frozen to 

 ice sheets may also be carried away by drifting ice. These factors should 

 be considered when designing structures on the Great Lakes and other 

 northern locations. 



h. Effects of Temperature and Fire . Stones, like most other materials, 

 expand upon being heated and contract when cooled. Unlike most other 

 materials, however, they do not quite return to their original volume when 

 cooled but show a permanent swelling. This swelling is determined using a 

 coefficient of temperature expansion, which is the change in length per 

 unit length per degree temperature change, for various stones (Mills, 

 Hayward, and Radar, 1955). These coefficients per Celsius ( Farenheit) 

 range as follows: 



(1) Granites, 0.000 005 60 to 0.000 007 34 (0.000 003 11 to 

 0.000 004 08); 



(2) limestones, 0.000 006 75 to 0.0.00 007 60 (0.000 003 75 to 

 0.000 004 20); 



(3) marbles, 0.000 006 50 to 0.000 010 12 (0.000 003 61 to 

 0.000 005 62); and 



(4) sandstones, 0.000 009 02 to 0.000 011 96 (0.000 005 01 to 

 0.000 006 22). 



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