EVOLUTION OF EARLY-AGE CRACKING IN CONCRETE BRIDGE DECKS INCORPORATING PRE-STRESSED CONCRETE PANELS AND INTERNALLY CURED CONCRETE

摘要

Deck cracking can be minimized by using a variety of techniques affecting structural design, materials selection, and construction procedures. Unfortunately, some approaches used for accelerated bridge construction, which are desirable to minimize disruptions to the traveling public, may compromise long-term deck performance by increasing the probability of deck cracking. The objective of this research was to monitor, document, and quantify early-age deck cracking on four newly constructed bridges that incorporated features related to both minimizing cracking and accelerating construction. Two bridge decks were constructed using a conventional concrete mixture, and two were constructed using a concrete mixture containing pre-wetted lightweight fine aggregate to facilitate internal curing and thereby reduce cracking. Each of the four bridge structures incorporated pre-stressed concrete panels placed between the girders to accelerate bridge construction. Deck distress surveys were conducted to quantify and compare the degree of surface cracking among the bridge decks at 5 months, 8 months, and 1 year following deck construction. While the use of internally cured concrete is recommended for reducing the occurrence of early-age cracking in concrete bridge decks, the distress data indicate that it will not achieve its maximum potential in terms of crack reduction when pre-stressed concrete panels are used in deck construction; both conventional and internally cured concrete decks are susceptible to reflection cracking from the butt joints between underlying panels. Comparing the loss in deck service life from premature cracking with the benefits of accelerated construction resulting from the use of such panels is recommended for future research.