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Figure 3-45. Freeze/thaw deterioration.

the mudline, is abraded by silt, sand, and debris churned up by moving water. Figure 3-47 illustrates the effects of abrasion on a concrete pile. Chemical Deterioration. The most significant and serious saltwater chemical reaction to hardened concrete is the combining of sulfates in seawater with chemicals in the cement paste, referred to as sulphate attack. This reaction can produce internal expansion and cause cracking. More commonly, however, the hydrate cement paste looses strength and becomes soft. Aggregate particles become exposed or fall from the concrete mass because of the weak cement paste.

Figure 3-46. Internal freezing of jetted-in concrete pile.

Figure 3-46. Internal freezing of jetted-in concrete pile.

Piles Internal Figure Axial Overloading. Deterioration of concrete piles from axial overloading can be a cause of eventual failure of the pile. Overloading can result from superimposed "dead" and "live" loads exceeding the bearing capacity of the pile, and also from over-stressing at the time of pile driving. Pile driving overloading often results in hairline cracks at the top of the pile or circumferential cracks at other locations along the pile that are difficult to see, as illustrated in Figure 3-48. As marine growth covers the pile, the cracks become extremely difficult to detect.

Concrete cap

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