Field Implementation and Performance of Fiber-Reinforced Low-Shrinkage Concrete for Bridge Deck Construction

This paper reports on the field implementation of fiber-reinforced concrete (FRC) used for redecking the two-span overpass bridge in Missouri. The spans measured 38.4 and 35.05 m in length. Modeling of the structural behavior of the bridge replacement deck indicated significantly high tensile stresses at midspan (up to 45 MPa) due to the continuity of the deck over the four precast main girders. Redecking of the bridge and casting of the central diaphragm were carried out continuously and necessitated 40 concrete truck deliveries of ${252\mathrm{m}}^3$ of FRC. Six sensor towers were installed in the bridge deck to monitor variations of internal relative humidity, temperature, and strain in the concrete, which were monitored for 260 days. The FRC made with 30% Class C fly ash replacement had slump varying between 150 and 255 mm, and the average 56-day compressive strength was 52.6 MPa. High tensile strain of up to $2,100\mu \mathrm{m}/\mathrm{m}$ was observed in the concrete near the diaphragm. The effect of the bridge’s own weight was predicted using a 3D finite element model. A strain model was devised to analyze the concrete embedded sensor data. The model was also used to calculate strains and concrete shrinkage on the first day as well as the load distribution factor, which is the ratio of the load carried by the concrete at a specific age to the load carried by the corrugated sheet supporting the fresh concrete after casting, where this factor is initially equal to zero and is close to 1 when the concrete developed its maximum strength.