Several researchers (Datta et al. , 1979, 1980, 1981; Agarwal, 1977; 

 and Demars et al. , 1976) have identified parameters that affect the engi- 

 neering behavior of calcareous soils. These parameters are carbonate 

 content, crushability , degree of cementation, index properties, and geo- 

 logic processes. These parameters are interrelated and none of them 

 alone provide a unique relationship to engineering behavior. 



There is no classification system that adequately characterizes the 

 engineering behavior of calcareous sediments; several have been proposed 

 (Noorany, 1982a; Demars et al., 1976; Demars, 1982; Datta et al. , 1981, 

 1982; Beringen et al., 1982). Datta and others suggested that is it 

 premature to propose engineering classification systems; cited as reasons, 

 among others, is that cementation and susceptibility to crushing cannot 

 be quantified. Beringen and others proposed using cone penetration test 

 (CPT) data to qualitatively measure cementation as a function of cone 

 resistance in conjunction with other classification data. While it is 

 apparent that progress in classification is being made, it is equally 

 apparent that years of data gathering will be required before a compre- 

 hensive and reliable classification system will evolve. 



A summary of engineering aspects of calcareous soils that are likely 

 to be relevant to pile behavior is provided: 



Index Properties 



• Calcareous soils have lower densities and higher intra-particle 

 voids than terrigenous soils. 



• Calcareous soils contain soft calcium carbonate minerals and 

 their grains are softer than quartz or silica sand. 



• The specific gravity, G , of calcareous sediments is usually 



higher than terrigenous soils. For example, the G values for 



the calcareous sands from Florida and Guam (Noorany, 1982b) are 



about 2.8 or more, whereas the G value for quartz is about 2.65. 



s 



Compressibility and Crushability 



• Calcareous soils are more compressible than terrigenous soils; 

 their compressibility results from grain crushing and the col- 

 lapse of grain-structure, therefore, volume changes are usually 

 permanent. 



• Coarser-grained calcareous sediments show a more significant 

 degree of degradation and grain crushing than finer-grained 

 sediments. 



• Grain crushing and the collapse of grain-structure can be induced 

 by applying either confining or shearing stresses. 



• Sediments with high carbonate content do not compress to as low 

 a final void ratio as sediments with low carbonate content. 



