What is a major cause of deck failure in concrete bridges?

A major cause of deck failure in concrete bridges is indeed the freeze-thaw cycles leading to spalling. This phenomenon occurs when moisture that has infiltrated the concrete structure freezes during cold weather. As the water freezes, it expands, exerting pressure on the surrounding concrete. When it thaws, the water contracts, leading to repeated cycles of expansion and contraction that can break down the concrete material over time.

These freeze-thaw cycles are particularly damaging when the concrete is not properly designed or when proper maintenance is neglected. Despite efforts to mitigate such conditions through the use of air-entrained concrete or effective sealants, the natural environment can still impose significant stress on the bridge deck. The result is spalling, which manifests as flaking or chipping of the concrete surface, ultimately compromising the structural integrity of the deck and leading to more significant failures if not addressed promptly.

Although other factors, such as inadequate drainage systems and increased traffic loads, can contribute to deck deterioration, freeze-thaw cycles specifically target the concrete's physical properties, making them a critical concern in regions subject to fluctuating temperatures. Proper design considerations and maintenance practices are thus essential to minimize the impact of these environmental effects on concrete bridge decks.