Long-term protection of bridge-deck systems with structural latex-modified concrete overlays

摘要

>Latex-modified concrete (LMC) overlays have performance characteristics that are superior to microsilica concrete (MSC) overlays and other overlay types. LMC provides unique features that are critical for fulfilling the functionality of the overlay. Polymerization of the latex creates a membrane around the LMC particles, resulting in a low-permeable product with inherent flexibility to accommodate freeze-and-thaw stresses. LMC overlays adhere properly to the deck substrate and have high early-age strength that allows for opening to traffic early. Toughness characteristics can be enhanced by adding synthetic fibers to the LMC to eliminate the possibility of early-age shrink - age cracking and to provide crack-arresting capabilities. Accordingly, the fibrous LMC overlay is the best overlay choice to ensure long-term durability with appropriate functionality. Major factors limit the popularity of the fibrous LMC overlays: >?? Installation of the fibrous LMC overlay requires the use of volumetric mobile trucks.>?? It is difficult to feed the right dosage of synthetic fibers to the LMC in a mobile truck.>?? The LMC has a short setting time.>?? The initial cost of the fibrous LMC overlay is high compared with the MSC overlay.>However, its ability to open early to traffic, durability, minimal maintenance cost, high-quality product, and structural advantages must be visualized in the cost comparison. This paper provides useful recommendations and guidelines about the practices involved in the design and construction of fibrous LMC overlays based on the findings of a four-year comprehensive experimental research program as well as other reliable studies. Structural advantages of fibrous LMC overlays and quantification to the live load and shrinkage-induced deck-overlay interfacial stresses are also discussed.